Search Results (140 total)

We measure the inclusive branching fractions of charm mesons into three mesons with large ss? content, namely, the ?, ?^? and ?. Data were accumulated with the CLEO-c detector. For D⁰ and D⁺ rates, we use 281??pb^-1 taken on the ?(3770) resonance, and for D_s⁺ rates, we use 195??pb^-1 taken at 4170 MeV. We find that the production rates of these particles are larger in D_s⁺ decays than in D⁰ and D⁺ decays. The ? rate, in particular, is 15 times greater. These branching fractions can be used to measure B_s yields either at the ?(5S) resonance or at hadron colliders.

Resistively shunted junction dynamics is applied to the three-dimensional uniformly frustrated XY model with randomly perturbed couplings, as a model for driven steady states in a type-II superconductor with quenched point pinning. For a disorder strength p strong enough to produce a vortex glass in equilibrium, we map the phase diagram as a function of temperature T and uniform driving current I. Using finite size analysis and averaging over many realizations of quenched randomness we find a first-order melting T_m(I) from a vortex line smectic to an anisotropic liquid.

We report a new measurement of the tt? production cross section in pp? collisions at a center-of-mass energy of 1.96 TeV using events with one charged lepton (electron or muon), missing transverse energy, and jets. Using 425??pb^-1 of data collected using the D0 detector at the Fermilab Tevatron Collider, and enhancing the tt? content of the sample by tagging b jets with a secondary vertex tagging algorithm, the tt? production cross section is measured to be ?_{pp? ?tt? +X}=6.6±0.9(stat+syst)±0.4(lum)??pb. This cross section is the most precise D0 measurement to date for tt? production and is in good agreement with standard model expectations.

We present measurements of the inclusive branching fractions for the decays D+?Xe+?e and D0?Xe+?e, using 281??pb-1 of data collected on the ?(3770) resonance with the CLEO-c detector. We find B(D0?Xe+?e)=(6.46±0.17±0.13)% and B(D+?Xe+?e)=(16.13±0.20±0.33)%. Using the known D meson lifetimes, we obtain the ratio ?D+sl/?D0sl=0.985±0.028±0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D+ and D0 have consistent shapes.

In this paper, we study the ambient pressure dependent optical absorption of gold following femtosecond laser pulse excitation. We find that gold exhibits a clear pressure dependent step function in its optical absorption. For the p-polarized 60-femtosecond laser pulses at 800 nm, the pressure threshold for the step change is found to be ?5×10^?3 torr and is nearly independent on the pump laser intensity. The enhanced absorption is attributed to the contribution of a layer of emitted electrons from the metal surface due to intense pulse excitation.

In this paper, we study triple-ionization-induced dissociation in N₂ and O₂ for laser polarization aligning either parallel or perpendicular along the molecular axis. For the first time, we demonstrate that vertical or nonvertical transition can be turned on and off by simply switching the laser polarization between being perpendicular and parallel to the molecular axis. We also show that the dependence of kinetic energy release on intensity can be used to distinguish vertical from nonvertical transition in triple-ionization-induced dissociation.

We report on a measurement of the B_d⁰ mixing frequency and the calibration of an opposite-side flavor tagger in the D0 experiment. Various properties associated with the b quark on the opposite side of the reconstructed B meson are combined using a likelihood-ratio method into a single variable with enhanced tagging power. Its performance is tested with data, using a large sample of reconstructed semileptonic B??D⁰X and B??D^*X decays, corresponding to an integrated luminosity of approximately 1??fb^-1. The events are divided into groups depending on the value of the combined tagging variable, and an independent analysis is performed in each group. Combining the results of these analyses, the overall effective tagging power is found to be ?D²=(2.48±0.21_-0.06^+0.08)%. The measured B_d⁰ mixing frequency ?m_d=0.506±0.020(stat)±0.016(syst)??ps^-1 is in good agreement with the world average value.

Recent direct searches for new massive particles place constraints on the free parameters of the littlest Higgs model. Depending on the choice of model free parameters, the direct-search limit on the global symmetry-breaking scale f can range from as low as a few hundred GeV to in excess of 4.5 TeV. The most stringent constraints are from exclusion of the A_H using high-mass dilepton resonance searches. The Z_H provides the best constraint in parameter regions where the A_H decouples from leptons. Current top pair resonance data approach but do not yet reach a useful limit in the anomaly-cancelling case, but do provide a constraint for a limited range of parameters in other cases. A neutral gauge boson is shown to be undetectable in dilepton resonances for a significant range of parameter space due to decoupling from standard model leptons, providing a counterexample to broad claims that a new neutral gauge boson (sometimes generically referred to as a Z^?) is ruled out to a high-mass scale.

We report the observation of B_s⁰-B? _s⁰ oscillations from a time-dependent measurement of the B_s⁰-B? _s⁰ oscillation frequency ?m_s. Using a data sample of 1??fb^-1 of pp? collisions at sqrt[s]=1.96??TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic B_s decays, 3100 partially reconstructed hadronic B_s decays, and 61?500 partially reconstructed semileptonic B_s decays. We measure the probability as a function of proper decay time that the B_s decays with the same, or opposite, flavor as the flavor at production, and we find a signal for B_s⁰-B? _s⁰ oscillations. The probability that random fluctuations could produce a comparable signal is 8×10^-8, which exceeds 5? significance. We measure ?m_s=17.77±0.10(stat)±0.07(syst)??ps^-1 and extract |V_td/V_ts|=0.2060±0.0007(?m_s)_-0.0060^+0.0081(?m_d+theor).

We report a measurement of the B_s⁰ lifetime in the semileptonic decay channel B_s⁰?D_s^-?⁺?X (and its charge conjugate), using approximately 0.4??fb^-1 of data collected with the D0 detector during 2002?2004. Using 5176 reconstructed D_s^-?⁺ signal events, we have measured the B_s⁰ lifetime to be ?(B_s⁰)=1.398±0.044(stat)_-0.025^+0.028(syst)??ps. This is the most precise measurement of the B_s⁰ lifetime to date.

The growth mechanism of pentacene film formation on SiO₂ substrate was investigated with a combination of atomic force microscopy measurements and numerical modeling. In addition to the diffusion-limited aggregation (DLA) that has already been shown to govern the growth of the ordered pentacene thin films, it is shown here that the Schwoebel barrier effect steps in and disrupts the desired epitaxial growth for the subsequent layers, leading to mound growth. The terraces of the growing mounds have a fractal dimension of 1.6, indicating a lateral DLA shape. This growth morphology thus combines horizontal DLA-like growth with vertical mound growth.

We develop systematically to all orders the forward scattering description for retarded amplitudes in field theories at zero temperature. Subsequently, through the application of the thermal operator, we establish the forward scattering description at finite temperature. We argue that, beyond providing a graphical relation between the zero temperature and the finite temperature amplitudes, this method is calculationally quite useful. As an example, we derive the important features of the one-loop retarded gluon self-energy in the hard thermal loop approximation from the corresponding properties of the zero temperature amplitude.

We demonstrate a general method of engineering the joint quantum state of photon pairs produced in spontaneous parametric down-conversion. The method makes use of a superlattice structure of nonlinear and linear materials, in conjunction with a broadband pump, to manipulate the group delays of the signal and idler photons relative to the pump pulse, and realizes photon pairs described by a joint spectral amplitude with arbitrary degree of entanglement. This method of group-delay engineering has the potential of synthesizing a broad range of states including factorizable states crucial for quantum networking and states optimized for Hong-Ou-Mandel interferometry. Experimental results for the latter case are presented, illustrating the principles of this approach.

We present an improved measurement of the ?^? meson energy spectrum in ?(1S) decays, using 1.2??fb^-1 of data taken at the ?(1S) center-of-mass energy with the CLEO III detector. We compare our results with models of the ?^? gluonic form factor that have been suggested to explain the unexpectedly large B??^?X_s rate. Models based on perturbative QCD fail to fit the data for large ?^? energies, and thus an explanation outside the realm of the Standard Model or an improved understanding of nonperturbative QCD effects may be needed to account for this large rate.

We present a measurement of the top quark mass with the matrix element method in the lepton+jets final state. As the energy scale for calorimeter jets represents the dominant source of systematic uncertainty, the matrix element likelihood is extended by an additional parameter, which is defined as a global multiplicative factor applied to the standard energy scale. The top quark mass is obtained from a fit that yields the combined statistical and systematic jet energy scale uncertainty. Using a data set of 0.4??fb^-1 taken with the D0 experiment at Run II of the Fermilab Tevatron Collider, the mass of the top quark is measured using topological information to be: m_top^?+jets(topo)=169.2_-7.4^+5.0(stat+JES)_-1.4^+1.5(syst)??GeV, and when information about identified b jets is included: m_top^?+jets(b-tag)=170.3_-4.5^+4.1(stat+  JES)_-1.8^+1.2(syst)??GeV. The measurements yield a jet energy scale consistent with the reference scale.

We search for decays of the type B_(s)⁰?h⁺h^?- (where h,h^?=K or ?) in 180??pb^-1 of p? p collisions collected at the Tevatron by the upgraded Collider Detector at Fermilab. We report the first observation of the new mode B_s⁰?K⁺K^- with a yield of 236±32 events, corresponding to (f_s/f_d)×B(B_s⁰?K⁺K^-)/B(B⁰?K⁺?^-)=0.46±0.08(stat)±0.07(syst), where f_s/f_d is the ratio of production fractions of B_s⁰ and B⁰. We find results in agreement with world averages for the B⁰ modes, and set the following new limits at 90% C.L.: B(B_s⁰?K^-?⁺)<5.6×10^-6 and B(B_s⁰??⁺?^-)<1.7×10^-6.

The effect of spontaneous decay on the linear polarizability of an atom is typically included by adding imaginary parts to the frequency denominators that appear in the Kramers-Heisenberg formula. It has been shown for a two-level atom with radiative broadening that these (frequency-dependent) imaginary parts must be included in both the resonant and antiresonant frequency denominators [P. W. Milonni and R. W. Boyd, Phys. Rev. A 69, 023814 (2004)]; however, the expression obtained by Milonni and Boyd for the polarizability does not satisfy the optical theorem, if contributions from non-rotating-wave terms are included. In this paper, we derive a more accurate expression for the polarizability. The calculations are rather complicated and require that we go beyond the standard Weisskopf-Wigner approximation. We present calculations carried out in both the Heisenberg and Schrödinger pictures, since they offer complementary methods for understanding the dynamics of the Rayleigh scattering associated with the atomic polarizability. Moreover, it is shown that the shifts associated with the excited state are not the Lamb shifts of an isolated atom, but depend on the dynamics of the atom-field interaction. Our results for the polarizability are consistent with those obtained recently by Loudon and Barnett using a Green?s-function approach.

Using 13.3??fb^-1 of e⁺e^- collision data taken in the ?(1S-4S) region with the CLEO III detector at the CESR collider, a search has been made for the new resonance Y(4260) recently reported by the BABAR Collaboration. The production of Y(4260) in initial state radiation (ISR), and its decay into ?⁺?^-J/?, are confirmed. A good quality fit to our data is obtained with a single resonance. We determine M(Y(4260))=(4284_-16⁺¹⁷(stat)±4(syst))??MeV/c², ?(Y(4260))=(73_-25⁺³⁹(stat)±5(syst))??MeV/c², and ?_ee(Y(4260))×B(Y(4260)??⁺?^-J/?)=(8.9_-3.1^+3.9(stat)±1.8(syst))??eV/c².

We measure the dimuon charge asymmetry A in pp? collisions at a center of mass energy sqrt[s]=1960??GeV. The data was recorded with the D0 detector and corresponds to an integrated luminosity of approximately 1.0??fb^-1. Assuming that the asymmetry A is due to asymmetric B⁰?B? ⁰ mixing and decay, we extract the CP-violation parameter of B⁰ mixing and decay: ?(?_B⁰) / 1+|?_B⁰|²=A_B⁰ / 4=  -0.0023±0.0011(stat)±0.0008(syst).A_B⁰ is the dimuon charge asymmetry from decays of B⁰B? ⁰ pairs. The general case, with CP violation in both B⁰ and B_s⁰ systems, is also considered. Finally we obtain the forward-backward asymmetry that quantifies the tendency of ?⁺ to go in the proton direction and ?^- to go in the antiproton direction. The results are consistent with the standard model and constrain new physics.

We propose a means to discriminate between the two basic variants of Little Higgs models, the Product Group and Simple Group models, at the next generation of colliders. It relies on a special coupling of light pseudoscalar particles present in Little Higgs models, the pseudoaxions, to the Z and the Higgs boson, which is present only in Simple Group models. We discuss the collider phenomenology of the pseudoaxion in the presence of such a coupling at the LHC, where resonant production and decay of either the Higgs or the pseudoaxion induced by that coupling can be observed for much of parameter space. The full allowed range of parameters, including regions where the observability is limited at the LHC, is covered by a future ILC, where double scalar production would be a golden channel to look for.

We search for excited and exotic muon states ?^* using an integrated luminosity of 371??pb^-1 of pp? collision data at sqrt[s]=1.96??TeV. We search for associated production of ??^* followed by the decay ?^*???. We compare the data to model predictions as a function of the mass of the excited muon M_?^*, the compositeness energy scale ?, and the gauge coupling factor f. No signal above the standard model expectation is observed. We exclude 107<M_?^*<853??GeV/c² for ?=M_?^* in the contact interaction model, and 100<M_?^*<410??GeV/c² for f/?=10^-2??GeV^-1 in the gauge-mediated model, both at the 95% confidence level.

A search for direct production of scalar bottom quarks (b?) is performed with 310??pb^-1 of data collected by the D0 experiment in pp? collisions at sqrt[s]=1.96??TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (??₁⁰), with ??₁⁰ assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m_b?, m_??1⁰) mass plane, improving significantly upon the results from run I of the Tevatron.

We present the results of a search for new physics in the jets plus missing transverse energy data sample collected from 368??pb^-1 of pp? collisions at sqrt[s]=1.96??TeV recorded by the Collider Detector at Fermilab. We compare the number of events observed in the data with a data-based estimate of the standard model backgrounds contributing to this signature. We observe no significant excess of events, and we interpret this null result in terms of lower limits on the fundamental Planck scale for a large extra dimensions scenario.

We present a measurement of the inclusive jet cross section in pp? interactions at sqrt[s]=1.96??TeV using 385??pb^-1 of data collected with the CDF II detector at the Fermilab Tevatron. The results are obtained using an improved cone-based jet algorithm (Midpoint). The data cover the jet transverse momentum range from 61 to 620??GeV/c, extending the reach by almost 150??GeV/c compared with previous measurements at the Tevatron. The results are in good agreement with next-to-leading order perturbative QCD predictions using the CTEQ6.1M parton distribution functions.

We propose an experiment which demonstrates the undoing of a weak continuous measurement of a solid-state qubit, so that any unknown initial state is fully restored. The undoing procedure has only a finite probability of success because of the nonunitary nature of quantum measurement, though it is accompanied by a clear experimental indication of whether or not the undoing has been successful. The probability of success decreases with increasing strength of the measurement, reaching zero for a traditional projective measurement. Measurement undoing (?quantum undemolition?) may be interpreted as a kind of quantum eraser, in which the information obtained from the first measurement is erased by the second measurement, which is an essential part of the undoing procedure. The experiment can be realized using quantum dot (charge) or superconducting (phase) qubits.

We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260??pb^-1. We study events with missing transverse energy and two acoplanar b jets, which provide sensitivity to the ZH production cross section in the ??? bb? channel, and to WH production when the lepton from the W??? decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on ?(pp? ?ZH/WH)×B(H?bb? ) from 3.4/8.3 to 2.5/6.3??pb, for Higgs-boson masses between 105 and 135 GeV.

We present a search for a neutral particle, pair produced in pp? collisions at sqrt[s]=1.96??TeV, which decays into two muons and lives long enough to travel at least 5 cm before decaying. The analysis uses ?380??pb^-1 of data recorded with the D0 detector. The background is estimated to be about one event. No candidates are observed, and limits are set on the pair-production cross section times branching fraction into dimuons + X for such particles. For a mass of 10 GeV and lifetime of 4×10^-11??s, we exclude values greater than 0.14 pb (95% C.L.). These results are used to limit the interpretation of NuTeV?s excess of dimuon events.

We present a measurement of the tt? production cross section using events with one charged lepton and jets from pp? collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318??pb^-1 of data collected with the CDF II detector, we measure the tt? production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9_-1.0^+1.0(stat)_-1.0^+1.1(syst)??pb. The cross section value assumes a top quark mass of m_t=178??GeV/c² in the acceptance corrections. The dependence of the cross section on m_t is presented in the paper. This result is consistent with other CDF measurements of the tt? cross section using different samples and analysis techniques, and has similar systematic uncertainties. We have also performed consistency checks by using the b-tagging probability function to vary the signal-to-background ratio and also using events that have at least two b-tagged jets.

We present a search for associated Higgs boson production in the process pp? ?WH?WWW^*?l^±?l^?±?^?+X in final states containing two like-sign isolated electrons or muons (e^±e^±, e^±?^±, or ?^±?^±). The search is based on D0 run II data samples corresponding to integrated luminosities of 360?380??pb^-1. No excess is observed over the predicted standard model background. We set 95% C.L. upper limits on ?(pp? ?WH)×Br(H?WW^*) between 3.2 and 2.8 pb for Higgs boson masses from 115 to 175 GeV.

We report a measurement of the tt? production cross section using the CDF II detector at the Fermilab Tevatron. The analysis is performed using 311??pb^-1 of pp? collisions at sqrt[s]=1.96??TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be ?_tt? =7.5±2.1(stat.)_-2.2^+3.3(syst.)_-0.4^+0.5(lumi.)??pb, which is consistent with the standard model prediction.

We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D⁺?K⁺?⁰, using 281??pb^-1 of data accumulated with the CLEO-c detector on the ?(3770) resonance. We find B(D⁺?K⁺?⁰)=(2.28±0.36±0.15±0.08)×10^-4, where the first uncertainty is statistical, the second is systematic, and the last error is due to the uncertainty in the reference mode branching fraction.

In the context of scalar field theories, both real and complex, we derive the cutting description at finite temperature (with zero/finite chemical potential) from the cutting rules at zero temperature through the action of a simple thermal operator. We give an alternative algebraic proof of the largest time equation which brings out the underlying physics of such a relation. As an application of the cutting description, we calculate the imaginary part of the one-loop retarded self-energy at zero/finite temperature and finite chemical potential and show how this description can be used to calculate the dispersion relation as well as the full physical self-energy of thermal particles.

We demonstrate in straightforward calculations that even under ideally weak noise the relaxation of bipartite open quantum systems contains elements not previously encountered in quantum noise physics. While additivity of decay rates is known to be generic for decoherence of a single system, we demonstrate that it breaks down for bipartite coherence of even the simplest composite systems.

In this paper, we study the dynamics of triple-ionization-induced dissociation in a heteronuclear diatomic molecule NO. Compared to homonuclear diatomic molecules, NO shows a greater complexity in its final states following triple ionization. By utilizing a well-established technique from the study of sequential versus nonsequential ionization, our study shows that both the N²⁺+O⁺ and N⁺+O²⁺ channels are predominately formed nonvertically through a relatively slowly dissociating N⁺+O⁺ state. Finally, we show that both the N²⁺+O⁺ and N⁺+O²⁺ channels are formed at nearly the same internuclear separation that is much smaller than the critical internuclear distance, indicating that dissociative ionization of high charge states in a molecule can occur as a molecule steadily expands from its equilibrium separation rather than always at the critical internuclear distance.

The atom fluctuation statistics of an ideal, mesoscopic, Bose-Einstein condensate are investigated from several different perspectives. By generalizing the grand canonical analysis (applied to the canonical ensemble problem), we obtain a self-consistent equation for the mean condensate particle number that coincides with the microscopic result calculated from the laser master equation approach. For the case of a harmonic trap, we obtain an analytic expression for the condensate particle number that is very accurate at all temperatures, when compared with numerical canonical ensemble results. Applying a similar generalized grand canonical treatment to the variance, we obtain an accurate result only below the critical temperature. Analytic results are found for all higher moments of the fluctuation distribution by employing the stochastic path integral formalism, with excellent accuracy. We further discuss a hybrid treatment, which combines the master equation and stochastic path integral analysis with results obtained based on the canonical ensemble quasiparticle formalism [Kocharovsky , Phys. Rev. A 61, 053606 (2000)], producing essentially perfect agreement with numerical simulation at all temperatures.

A search for the production of neutral Higgs bosons ? decaying into ?⁺?^- final states in pp? collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325??pb^-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for ?b(b? )?bb? b(b? ) and are interpreted in the minimal supersymmetric standard model.

We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon sneutrinos in the channels ?????₁⁰?, ?????_2,3,4⁰?, and ??_????_1,2^±?. We analyzed 0.38??fb^-1 of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function of slepton and gaugino masses. In the framework of minimal supergravity, we set limits on the coupling parameter ?₂₁₁^?, extending significantly previous results obtained in Run I of the Tevatron and at the CERN LEP collider.

We present an investigation of nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three-wave coupling coefficients and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfvén-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfvén wave frequency. The implication of our results to astrophysical dusty plasmas is discussed.

Ensembles of 400?000 two-electron trajectories in three space dimensions are used with Newtonian equations of motion to track atomic double ionization under very strong laser fields. We report a variable time lag between e-e collision and double ionization, and find that the time lag plays a key role in the emergence directions of the electrons. These are precursors to production of electron momentum distributions showing substantial new agreement with experimental data.

Limits are set on anomalous WW? and WWZ trilinear gauge couplings using W⁺W^-?e⁺?_ee^-?? _e, W⁺W^-?e^±?_e?^??_?, and W⁺W^-??⁺?_??^-?? _? events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250??pb^-1 of integrated luminosity at sqrt[s]=1.96??TeV. Under the assumption that the WW? couplings are equal to the WWZ couplings and using a form factor scale of ?=2.0??TeV, the combined 95% C.L. one-dimensional coupling limits from all three channels are -0.32<??<0.45 and -0.29<?<0.30.

We present model independent measurements of the helicity basis form factors in the decay D⁺?K^-?⁺e⁺?_e obtained from about 2?800 decays reconstructed from a 281??pb^-1 data sample collected at the ?(3770) center-of-mass energy with the CLEO-c detector. We confirm the existence of a previously observed spin-zero K^-?⁺ component interfering with the K? ^*0 amplitude. We see no evidence for additional d- or f-wave contributions.

We report on the experimental realization of large fractional pulse delays in a hot, Doppler-broadened rubidium vapor. A pump laser burns a deep spectral hole in the inhomogeneously broadened vapor. The delay is shown to be widely tunable by both power broadening the resonance and frequency modulating the pump laser. The simplicity of the scheme opens up the possibility for practical optical delays and buffers.

We describe a measurement of the top quark mass using events with two charged leptons collected by the CDF II detector from pp? collisions with sqrt[s]=1.96??TeV at the Fermilab Tevatron. The likelihood in top quark mass is calculated for each event by convoluting the leading order matrix element describing qq? ?tt? ?b??_?b? ?^??_?^? with detector resolution functions. The presence of background events in the data sample is modeled using similar calculations involving the matrix elements for major background processes. In a data sample with integrated luminosity of 340??pb^-1, we observe 33 candidate events and measure M_top=165.2±6.1(stat.)±3.4(syst.)??GeV/c². This measurement represents the first application of this method to events with two charged leptons and is the most precise single measurement of the top quark mass in this channel.

We present a measurement of R_B, the ratio of the branching fraction for the rare decay D⁰?K⁺?^- to that for the Cabibbo-favored decay D⁰?K^-?⁺. Charge-conjugate decays are implicitly included. A signal of 2005±104 events for the decay D⁰?K⁺?^- is obtained using the CDF II detector at the Fermilab Tevatron collider. The data set corresponds to an integrated luminosity of 0.35??fb^-1 produced in p? p collisions at sqrt[s]=1.96??TeV. Assuming no mixing, we find R_B=[4.05±0.21(stat)±0.11(syst)]×10^-3. This measurement is consistent with the world average, and comparable in accuracy with the best measurements from other experiments.

We present a measurement of the top quark pair production cross section in pp? collisions at sqrt[s]=1.96??TeV using 318??pb^-1 of data collected with the Collider Detector at Fermilab. We select tt? decays into the final states e?+jets and ??+jets, in which at least one b quark from the t-quark decays is identified using a secondary vertex-finding algorithm. Assuming a top quark mass of 178??GeV/c², we measure a cross section of 8.7±0.9(stat)_-0.9^+1.1(syst)??pb. We also report the first observation of tt? with significance greater than 5? in the subsample in which both b quarks are identified, corresponding to a cross section of 10.1_-1.4^+1.6(stat)_-1.3^+2.0(syst)??pb.

We present the results of a search for standard model Higgs boson production with decay to WW^*, identified through the leptonic final states e⁺e^-?? ?,e^±?^??? ? and ?⁺?^-?? ?. This search uses 360??pb^-1 of data collected from pp? collisions at sqrt[s]=1.96??TeV by the upgraded Collider Detector at Fermilab (CDF II). We observe no signal excess and set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson to WW^* or any new scalar particle with similar decay products. These upper limits range from 5.5 to 3.2 pb for Higgs boson masses between 120 and 200??GeV/c².

We analyze the large-order behavior of the perturbative weak-field expansion of the effective Lagrangian density of a massive scalar in de Sitter and anti?de Sitter space, and show that this perturbative information is not sufficient to describe the nonperturbative behavior of these theories, in contrast to the analogous situation for the Euler-Heisenberg effective Lagrangian density for charged scalars in constant electric and magnetic background fields. For example, in even-dimensional de Sitter space there is particle production, but the effective Lagrangian density is nevertheless real, even though its weak-field expansion is a divergent nonalternating series whose formal imaginary part corresponds to the correct particle production rate. This apparent puzzle is resolved by considering the full nonperturbative structure of the relevant Feynman propagators, and cannot be resolved solely from the perturbative expansion.

A measurement of the inclusive bottom jet cross section is presented for events containing a Z boson in pp? collisions at sqrt[s]=1.96??TeV using the Collider Detector at Fermilab. Z bosons are identified in their electron and muon decay modes, and b jets with E_T>20??GeV and |?|<1.5 are identified by reconstructing a secondary decay vertex. The measurement is based on an integrated luminosity of about 330??pb^-1. A cross section times branching ratio of ?(Z+b??jets)×B(Z??⁺?^-)=0.93±0.36??pb is found, where B(Z??⁺?^-) is the branching ratio of the Z boson or ?^* into a single flavor dilepton pair (e or ?) in the mass range between 66 and 116??GeV/c². The ratio of b jets to the total number of jets of any flavor in the Z sample, within the same kinematic range as the b jets, is 2.36±0.92%. Here, the uncertainties are the quadratic sum of statistical and systematic uncertainties. Predictions made with next-to-leading order QCD agree, within experimental and theoretical uncertainties, with these measurements.

We have studied the Cabibbo-suppressed decay mode D⁰?K⁺K^-?⁰ using a Dalitz plot technique and find the strong phase difference ?_D??_K^*-K⁺-?_K^*+K^-=332°±8°±11° and relative amplitude r_D?a_K^*-K⁺/a_K^*+K^-=0.52±0.05±0.04. This measurement indicates significant destructive interference between D⁰?K⁺(K^-?⁰)_K^*- and D⁰?K^-(K⁺?⁰)_K^*+ in the Dalitz plot region where these two modes overlap. This analysis uses 9.0??fb^-1 of data collected at sqrt[s]?10.58??GeV with the CLEO III detector.

A medium-spin isomer in ¹⁹⁷Au is identified with t_1/2=150(5) ns following a multinucleon transfer reaction between an 850-MeV ¹³⁶Xe beam and a ¹⁹⁸Pt target. The transitions identified here are considered and possible configurations for the associated levels discussed. In addition, a newly observed out-of-beam transition in ¹⁹⁵Au is briefly reported.

The PHOBOS experiment at the BNL Relativistic Heavy Ion Collider has measured the total multiplicity of primary charged particles as a function of collision centrality in Au+Au collisions at sqrt[s_NN]= 19.6, 130, and 200 GeV. An approximate independence of ?N_ch?/?N_part/2? on the number of participating nucleons is observed, reminiscent of ?wounded nucleon? scaling (N_ch?N_part) observed in proton-nucleus collisions. Unlike p+A, the constant of proportionality does not seem to be set by the pp/p? p data at the same energy. Rather, there seems to be a surprising correspondence with the total multiplicity measured in e⁺e^- annihilations, as well as the rapidity shape measured over a large range. The energy dependence of the integrated multiplicity per participant pair shows that e⁺e^- and A+A data agree over a large range of center-of-mass energies (sqrt[s]>20 GeV), and pp/p? p data can be brought to agree approximately with the e⁺e^- data by correcting for the typical energy taken away by leading particles. This is suggestive of a mechanism for soft particle production that depends mainly on the amount of available energy. It is conjectured that the dominant distinction between A+A and p+p collisions is the multiple collisions per participant, which appears to be sufficient to substantially reduce the energy taken away by leading particles.

We describe first-principles in-plane calculations of nonsequential triple ionization of atoms in a linearly polarized intense laser pulse. In a fully classically correlated description, all three electrons respond dynamically to the nuclear attraction, the pairwise e-e repulsions, and the laser force throughout the duration of a 780 nm laser pulse. Nonsequential ejection is shown to occur in a multielectron, possibly multicycle and multidimensional, rescattering sequence that is coordinated by a number of sharp transverse recollimation impacts.

We propose a scheme for quantum cryptography that uses the squeezing phase of a two-mode squeezed state to transmit information securely between two parties. The basic principle behind this scheme is the fact that each mode of the squeezed field by itself does not contain any information regarding the squeezing phase. The squeezing phase can only be obtained through a joint measurement of the two modes. This, combined with the fact that it is possible to perform remote squeezing measurements, makes it possible to implement a secure quantum communication scheme in which a deterministic signal can be transmitted directly between two parties while the encryption is done automatically by the quantum correlations present in the two-mode squeezed state.

We present a search for the flavor-changing neutral current decay B_s⁰???⁺?^- using about 0.45??fb^-1 of data collected in pp? collisions at sqrt[s]=1.96??TeV with the D0 detector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to B_s⁰?J/?? of B(B_s⁰???⁺?^-) / B(B_s⁰?J/??)<4.4×10^-3 at the 95% C.L. Using the central value of the world average branching fraction of B_s⁰?J/??, the limit corresponds to B(B_s⁰???⁺?^-)<4.1×10^-6 at the 95% C.L., the most stringent upper bound to date.

From e⁺e^- collision data acquired with the CLEO-c detector at CESR, we search for the non-DD? decays ?(3770)???_cJ, with ?_cJ reconstructed in four exclusive decays modes containing charged pions and kaons. We report the first observation of such decays for J=0 with a branching ratio of (0.73±0.07±0.06)%. The rates for different J are consistent with the expectations assuming ?(3770) is predominantly a 1³D₁ state of charmonium, but only if relativistic corrections are applied.

We present the first precise measurement of the B_s⁰-B? _s⁰ oscillation frequency ?m_s. We use 1??fb^-1 of data from pp? collisions at sqrt[s]=1.96??TeV collected with the CDF II detector at the Fermilab Tevatron. The sample contains signals of 3600 fully reconstructed hadronic B_s decays and 37?000 partially reconstructed semileptonic B_s decays. We measure the probability as a function of proper decay time that the B_s decays with the same, or opposite, flavor as the flavor at production, and we find a signal consistent with B_s⁰-B? _s⁰ oscillations. The probability that random fluctuations could produce a comparable signal is 0.2%. Under the hypothesis that the signal is due to B_s⁰-B? _s⁰ oscillations, we measure ?m_s=17.31_-0.18^+0.33(stat)±0.07(syst)??ps^-1 and determine |V_td/V_ts|=0.208_-0.002^+0.001(expt)_-0.006^+0.008(theor).

The charged-particle pseudorapidity density for Au+Au collisions at sqrt[s_NN]=62.4 GeV has been measured over a wide range of impact parameters and compared to results obtained at other energies. As a function of collision energy, the pseudorapidity distribution grows systematically both in height and width. The midrapidity density is found to grow approximately logarithmically between BNL Alternating Gradient Synchrotron (AGS) energies and the top BNL Relativistic Heavy Ion Collider (RHIC) energy. There is also an approximate factorization of the centrality and energy dependence of the midrapidity yields. The new results at sqrt[s_NN]=62.4 GeV confirm the previously observed phenomenon of ?extended longitudinal scaling? in the pseudorapidity distributions when viewed in the rest frame of one of the colliding nuclei. It is also found that the evolution of the shape of the distribution with centrality is energy independent, when viewed in this reference frame. As a function of centrality, the total charged particle multiplicity scales linearly with the number of participant pairs as it was observed at other energies.

The informational approach to continuous quantum measurement is derived from positive operator-valued measure formalism for a mesoscopic scattering detector measuring a charge qubit. Quantum Bayesian equations for the qubit density matrix are derived, and cast into the form of a stochastic conformal map. Measurement statistics are derived for kicked quantum nondemolition measurements, combined with conditional unitary operations. These results are applied to derive a feedback protocol to produce an arbitrary pure state after a weak measurement, as well as to investigate how an initially mixed state becomes purified with and without feedback.

The NuTeV experiment at Fermilab has obtained a unique high-statistics sample of neutrino and antineutrino interactions using its high-energy sign-selected beam. We present a measurement of the differential cross section for charged-current neutrino and antineutrino scattering from iron. We determine the relative ?? to ? cross section, r=?^?? /?^?, at high energy with errors a factor of 2 smaller than the previous world average. Structure functions, F₂(x,Q²) and xF₃(x,Q²), are determined by fitting the inelasticity, y, dependence of the cross sections. This measurement has significantly improved systematic precision as a consequence of more precise understanding of hadron and muon energy scales.

We present a theory describing the transients and rise times of the refractive Kerr nonlinearity which is enhanced using electromagnetically induced transparency (EIT). We restrict our analysis to the case of a pulsed signal field with continuous-wave EIT fields, and all fields are well below saturation. These restrictions enable the reduction of an EIT Kerr, four-level, density-matrix equation to a two-level Bloch-vector equation which has a simple and physically intuitive algebraic solution. The physically intuitive picture of a two-level Bloch vector provides insights that are easily generalized to more complex and experimentally realistic models. We consider generalization to the cases of Doppler broadening, many-level EIT systems (we consider the D1 line of ⁸⁷Rb), and optically thick media. For the case of optically thick media we find that the rise time of the refractive EIT Kerr effect is proportional to the optical thickness. The rise time of the refractive EIT Kerr effect sets important limitations for potential few-photon applications.

Using the current world?s largest data sample of ?(3770) decays, we present results of a search for the non-DD? decay ?(3770)?K_S⁰K_L⁰. We find no signal, and obtain an upper limit of ?(e⁺e^-??(3770)?K_S⁰K_L⁰)<0.07??pb at 90% confidence level (CL). Our result tests a theoretical prediction for the upper bound on B(?(3770)?K_S⁰K_L⁰) based on a charmonia-mixing model.

Using a sample of 3.08×10⁶ ?(2S) decays collected at sqrt[s]=3.686??GeV with the CLEO detector at the Cornell Electron Storage Ring, we have measured the branching fractions for ?(2S) decays to pseudoscalar pairs ?⁺?^-, K⁺K^- and K_S⁰K_L⁰. We obtain B(?(2S)??⁺?^-)<2.1×10^-5 (90% C.L.), B(?(2S)?K⁺K^-)=(6.3±0.6(stat)±0.3(syst))×10^-5, and B(?(2S)?K_S⁰K_L⁰)=(5.8±0.8(stat)±0.4(syst))×10^-5. The branching fractions allow extraction of the relative phase ?=(95±15)° and strength ratio R=(2.5±0.4) of the three-gluon and one-photon amplitudes for these modes.

We present results of a search for anomalous production of events containing a charged lepton (?, either e or ?) and a photon (?), both with high transverse momentum, accompanied by additional signatures X, including missing transverse energy (E?_T) and additional leptons and photons. We use the same selection criteria as in a previous CDF search but with a substantially larger data set, 305???pb^-1, a pp? collision energy of 1.96 TeV, and the CDF II detector. We find 42 ??E?_T events versus an expectation of 37.3±5.4 events. We observe 31 ???+X events versus an expectation of 23.0±2.7 events. We find no events similar to the run I ee??E?_T event.

We have searched for a heavy resonance decaying into a Z+jet final state in pp? collisions at a center of mass energy of 1.96??TeV at the Fermilab Tevatron collider using the D0 detector. No indication for such a resonance was found in a data sample corresponding to an integrated luminosity of 370??pb^-1. We set upper limits on the cross section times branching fraction for heavy resonance production at the 95% C.L. as a function of the resonance mass and width. The limits are interpreted within the framework of a specific model of excited quark production.

A kicked quantum nondemolition measurement is introduced, where a qubit is weakly measured by pumping current. Measurement statistics are derived for weak measurements combined with single-qubit unitary operations. These results are applied to violate a generalization of the Leggett-Garg inequality. The violation is related to the failure of the noninvasive detector assumption, and may be interpreted as either intrinsic detector backaction, or the qubit entangling the microscopic detector excitations. The results are discussed in terms of a quantum point contact kicked by a pulse generator, measuring a double quantum dot.

We report results of a study of the B_s⁰ oscillation frequency using a large sample of B_s⁰ semileptonic decays corresponding to approximately 1??fb^-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider in 2002?2006. The amplitude method gives a lower limit on the B_s⁰ oscillation frequency at 14.8??ps^-1 at the 95% C.L. At ?m_s=19??ps^-1, the amplitude deviates from the hypothesis A=0 (1) by 2.5 (1.6) standard deviations, corresponding to a two-sided C.L. of 1% (10%). A likelihood scan over the oscillation frequency, ?m_s, gives a most probable value of 19??ps^-1 and a range of 17<?m_s<21??ps^-1 at the 90% C.L., assuming Gaussian uncertainties. This is the first direct two-sided bound measured by a single experiment. If ?m_s lies above 22??ps^-1, then the probability that it would produce a likelihood minimum similar to the one observed in the interval 16?22??ps^-1 is (5.0±0.3)%.

Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays ?(1S)??gg, ?(2S)??gg, ?(3S)??gg. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: (a) background estimates (primarily from ?⁰ decays) are based on isospin symmetry rather than a determination of the ?⁰ spectrum, which permits measurement of the ?(2S) and ?(3S) direct photon spectra without explicit corrections for ?⁰ backgrounds from, e.g., ?_bJ states, (b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, and c) we use the high-statistics sample of ?(2S)????(1S) to obtain a tagged sample of ?(1S)??+X events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay ??ggg??(R_?=B(gg?)/B(ggg)) to be R_?(1S)=(2.70±0.01±0.13±0.24)%, R_?(2S)=(3.18±0.04±0.22±0.41)%, and R_?(3S)=(2.72±0.06±0.32±0.37)%, where the errors shown are statistical, systematic, and theoretical model dependent, respectively. Given a value of Q², one can estimate a value for the strong coupling constant ?_s(Q²) from R_?.

Forward-backward correlations of charged-particle multiplicities in symmetric bins in pseudorapidity are studied to gain insight into the underlying correlation structure of particle production in Au+Au collisions. The PHOBOS detector is used to measure integrated multiplicities in bins centered at ?, defined within |?|<3, and covering intervals ??. The variance ?_C² of a suitably defined forward-backward asymmetry variable C is calculated as a function of ?,??, and centrality. It is found to be sensitive to short-range correlations, and the concept of ?clustering? is used to interpret comparisons to phenomenological models.

We show analytically that bright and dark spatial self-similar waves can propagate in graded-index amplifiers exhibiting self-focusing or self-defocusing Kerr nonlinearities. The intensity profiles of the novel waves are identical with those of fundamental bright or dark spatial solitons supported by homogeneous passive waveguides with the same type of nonlinearity. Thus, we reveal a previously unnoticed connection between spatial solitons and self-similar waves. We also suggest that the discovered self-similar waves can be used in a promising scheme for the amplification and focusing of spatial solitons in future all-optical networks.

We report on measurements of directed flow as a function of pseudorapidity in Au+Au collisions at energies of sqrt[s_NN]=19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the BNL Relativistic Heavy Ion Collider. These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.

We present a measurement of the B_c⁺ meson lifetime in the decay mode B_c⁺?J/?e⁺?_e using the Collider Detector at Fermilab II detector at the Fermilab Tevatron Collider. From a sample of about 360??pb^-1 of pp? collisions at sqrt[s]=1.96??TeV, we reconstruct J/?e⁺ pairs with invariant mass in the kinematically allowed range 4<M_J/?e<6??GeV/c². A fit to the decay-length distribution of 238 signal events yields a measured B_c⁺ meson lifetime of 0.463+0.073 / -0.065(stat)±0.036(syst)??ps.

In this Letter, we report, for the first time in the multiphoton ionization regime, a comparison study of single-electron ionization of diatomic molecules versus rare gas atoms with virtually the same ionization potentials. In comparing N₂⁺ to Ar⁺, a higher ion signal is seen in N₂⁺ compared to Ar⁺ for linear polarization but the difference vanishes in circularly polarized light. In comparing O₂⁺ to Xe⁺, we observe a suppression in O₂⁺ compared to Xe⁺ for both linear and circular polarization but this suppression exhibits an intensity dependence; i.e., there is little suppression for O₂⁺ at the lowest intensity range, but the suppression becomes increasingly stronger as the laser intensity increases. The multielectron screening model is used to discuss possible mechanisms of this intensity dependent suppression in O₂⁺ in the multiphoton ionization regime.

The idea of quantum relativity as a generalized, or rather deformed, version of Einstein (special) relativity has been taking shape in recent years. Following the perspective of deformations, while staying within the framework of Lie algebra, we implement explicitly a simple linear realization of the relativity symmetry, and explore systematically the resulting physical interpretations. Some suggestions we make may sound radical, but are arguably natural within the context of our formulation. Our work may provide a new perspective on the subject matter, complementary to the previous approach(es), and may lead to a better understanding of the physics.

We describe a measurement of the top quark mass from events produced in pp? collisions at a center-of-mass energy of 1.96 TeV, using the Collider Detector at Fermilab. We identify tt? candidates where both W bosons from the top quarks decay into leptons (e?, ??, or ??) from a data sample of 360??pb^-1. The top quark mass is reconstructed in each event separately by three different methods, which draw upon simulated distributions of the neutrino pseudorapidity, tt? longitudinal momentum, or neutrino azimuthal angle in order to extract probability distributions for the top quark mass. For each method, representative mass distributions, or templates, are constructed from simulated samples of signal and background events, and parametrized to form continuous probability density functions. A likelihood fit incorporating these parametrized templates is then performed on the data sample masses in order to derive a final top quark mass. Combining the three template methods, taking into account correlations in their statistical and systematic uncertainties, results in a top quark mass measurement of 170.1±6.0(stat.)±4.1(syst.)??GeV/c².

We consider group delay and broadening using two strongly absorbing and widely spaced resonances. We derive relations which show that very large pulse bandwidths coupled with large group delays and small broadening can be achieved. Unlike single resonance systems, the dispersive broadening dominates the absorptive broadening which leads to a dramatic increase in the possible group delay. We show that the double resonance systems are excellent candidates for realizing all-optical delay lines. We report on an experiment which achieved up to 50 pulse delays with 40% broadening.

We report the first observation of B_s⁰??(2S)? decay in pp? collisions at sqrt[s]=1.96??TeV using 360??pb^-1 of data collected by the CDF II detector at the Fermilab Tevatron. We observe 20.2±5.0 and 12.3±4.1 B_s⁰??(2S)? candidates, in ?(2S)??⁺?^- and ?(2S)?J/??⁺?^- decay modes, respectively. We present a measurement of the relative branching fraction B(B_s⁰??(2S)?)/B(B_s⁰?J/??)=0.52±0.13(stat)±0.04(syst)±0.06(BR) using the ?(2S)??⁺?^- decay mode.

We test whether or not the ? lepton manifests the same couplings as the ? lepton by investigating the relative decay rates in purely leptonic D⁺ meson decays. We use 281??pb^-1 of data accumulated at the ?(3770) resonance with the CLEO-c detector, to limit B(D⁺??⁺?)<2.1×10^-3 at 90% confidence level (C.L.), thus allowing us to place the first upper limit on the ratio R=?(D⁺??⁺?)/?(D⁺??⁺?). The ratio of R to the standard model expectation of 2.65 then is <1.8 at 90% C.L., consistent with the prediction of lepton universality.

We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F₀ and F₊, using approximately 200??pb^-1 of p? p collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom-quark jet in the decay t?Wb???b (where ?=e or ?), and the transverse momentum of the charged lepton. Constrained fits yield F₀=0.74_-0.34^+0.22, and F₊<0.27 at the 95% confidence level. These measurements are consistent with the standard model predictions.

Nanograined materials have some unusual properties. To maintain the small size of the grains, grain growth should be avoided. But recently grain growth has been observed under an indenter at liquid-nitrogen temperatures. Such grain growth has never been reported before. How can this happen and how can it be prevented? These questions are answered here using a simple tilt boundary. It is found that high purity and nonequilibrium structure are necessary conditions for mechanical grain growth. The material must be pure enough so that free dislocations are available to move out of the boundary. But the boundary should not be in the lowest-energy state so that extra dislocations are available to be emitted by stress. Based on these conditions, methods can be devised to avoid low temperature grain growth.

We present the results of a search for the production of an excited state of the muon, ?^*, in proton antiproton collisions at sqrt[s]=1.96??TeV. The data have been collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 380??pb^-1. We search for ?^* in the process pp? ??^*?, with the ?^* subsequently decaying to a muon plus photon. No excess above the standard model expectation is observed in data. Interpreting our data in the context of a model that describes ?^* production by four-fermion contact interactions and ?^* decay via electroweak processes, we set a 95% confidence level production cross section upper limit ranging from 0.057 to 0.112 pb, depending on the mass of the excited muon. Choosing the scale for contact interactions to be ?=1??TeV, excited muon masses below 618 GeV are excluded.

We present transverse momentum distributions of charged hadrons produced in Cu+Cu collisions at sqrt[s_NN]=62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25<p_T<5.0??GeV/c at sqrt[s_NN]=62.4??GeV and 0.25<p_T<7.0??GeV/c at sqrt[s_NN]=200??GeV, in a pseudorapidity range of 0.2<?<1.4. The nuclear modification factor R_AA is calculated relative to p+p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R_AA is observed to be systematically larger in Cu+Cu collisions compared to Au+Au. However, for the same number of participating nucleons, R_AA is essentially the same in both systems over the measured range of p_T, in spite of the significantly different geometries of the Cu+Cu and Au+Au systems.

We describe a general search for resonances decaying to a neutral e? final state in pp? collisions at a center-of-mass energy of 1.96 TeV. Using a data sample representing 344??pb^-1 of integrated luminosity recorded by the Collider Detector at Fermilab II experiment, we compare standard model predictions with the number of observed events for invariant masses between 50 and 800??GeV/c². Finding no significant excess (5 events observed vs 7.7±0.8 expected for M_e?>100??GeV/c²), we set limits on sneutrino and Z^? masses as functions of lepton family number violating couplings.

We search for Z^? bosons in dielectron events produced in pp? collisions at sqrt[s]=1.96??TeV, using 0.45??fb^-1 of data accumulated with the Collider Detector at Fermilab II detector at the Fermilab Tevatron. To identify the Z^??e⁺e^- signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z^? mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z^?, as well as on the contact-interaction mass scales for different helicity structure scenarios.

We search for pair-produced Dirac magnetic monopoles in 35.7??pb^-1 of proton-antiproton collisions at sqrt[s]=1.96??TeV with the Collider Detector at Fermilab (CDF). We find no monopole candidates corresponding to a 95% confidence-level cross-section limit ?<0.2??pb for a monopole with mass between 200 and 700??GeV/c². Assuming a Drell-Yan pair-production mechanism, we set a mass limit m>360??GeV/c².

We present a measurement of the tt? production cross section in pp? collisions at sqrt[s]=1.96??TeV which uses events with an inclusive signature of significant missing transverse energy and jets. This is the first measurement which makes no explicit lepton identification requirements, so that sensitivity to W??? decays is maintained. Heavy flavor jets from top quark decay are identified with a secondary vertex tagging algorithm. From 311??pb^-1 of data collected by the Collider Detector at Fermilab, we measure a production cross section of 5.8±1.2(stat)_-0.7^+0.9(syst)??pb for a top quark mass of 178??GeV/c², in agreement with previous determinations and standard model predictions.

We measure the masses of b hadrons in exclusively reconstructed final states containing a J/???^-?⁺ decay using 220??pb^-1 of data collected by the CDF II experiment. We find: m(B⁺)=5279.10±0.41_(stat.)±0.36_(sys.)??MeV/c², m(B⁰)=5279.63±0.53_(stat.)±0.33_(sys.)??MeV/c², m(B_s⁰)=5366.01±0.73_(stat.)±0.33_(sys.)??MeV/c², m(?_b⁰)=5619.7±1.2_(stat.)±1.2_(sys.)??MeV/c². m(B⁺)-m(B⁰)=-0.53±0.67_(stat.)±0.14_(sys.)??MeV/c², m(B_s⁰)-m(B⁰)=86.38±0.90_(stat.)±0.06_(sys.)??MeV/c², m(?_b⁰)-m(B⁰)=339.2±1.4_(stat.)±0.1_(sys.)??MeV/c². The measurements of the B_s⁰, ?_b⁰ mass, m(B_s⁰)-m(B⁰) and m(?_b⁰)-m(B⁰) mass difference are of better precision than the current world averages.

In this paper, we report the first comparison study between N₂ and O₂ on their triple-ionization-induced dissociation channels using near-IR 800-nm ultrashort laser pulses. Our experiment shows that the O²⁺+O⁺ channel is predominately formed nonvertically through the intermediate O⁺+O⁺ channel, while the N²⁺+N⁺ channel appears to be formed vertically at the lower intensity range but nonvertically at higher intensities. Interestingly, N²⁺+N⁺ appears to be in the electronically excited state when it is reached vertically in the lower intensity range. The different triple ionization and dissociation behaviors between N₂ and O₂ can be understood by considering the ionization dynamics of the two molecules in our ultrashort laser pulses.

We have developed a two-macroparticle bunch to explore the longitudinal beam dynamics through various components of the Fermilab/NICADD photoinjector. Such a two-macroparticle bunch is generated by splitting the ultraviolet pulse from the photocathode drive laser. The presented method allows the exploration of radio-frequency-induced compression in the 1.625 cell radio frequency gun and the booster cavity. It also allows a direct measurement of the momentum compaction of the magnetic bunch compressor. The measurements are compared with analytical and numerical models.

We report an observation of the decay B_s⁰?D_s^-?⁺ in pp? collisions at sqrt[s]=1.96??TeV using 115??pb^-1 of data collected by the CDF II detector at the Fermilab Tevatron. We observe 83±11(stat) B_s⁰?D_s^-?⁺ candidates, representing a large increase in statistics over previous measurements and the first observation of this decay at a pp? collider. We present the first measurement of the relative branching fraction B(B_s⁰?D_s^-?⁺)/B(B⁰?D^-?⁺)=1.32±0.18(stat)±0.38(syst). We also measure B(B⁺?D? ⁰?⁺)/B(B⁰?D^-?⁺)=1.97±0.10(stat)±0.21(syst), which is consistent with previous measurements.

We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M_? of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in future network inspiral analyses.

The qubit entanglement induced by quasiparticle excitations in the Heisenberg spin chain and its relationship to the Bethe ansatz structure of the eigenmodes is studied. A phenomenon called entanglement quenching, which suppresses eigenstate entanglement, is described and shown to be mediated by Goldstone magnons. This form of quantum noise elucidates the absence of thermal entanglement in ferromagnets [J. S. Pratt, Phys. Rev. Lett. 93, 237605 (2004)]. Scattering states are characterized by short-range entanglement and never exhibit entanglement at the longest range. In contrast, entanglement in bound states typically increases with qubit separation. These results should be experimentally verifiable in quasi-one-dimensional organocopper spin chains and in linear quantum dot arrays.

From e⁺e^- collision data acquired with the CLEO detector at the Cornell Electron Storage Ring, we observe the non-DD? decay ?(3770)???_c1 with a statistical significance of 6.6 standard deviations, using the two-photon cascades to J/? and J/???⁺?^-. We determine ?(e⁺e^-??(3770))×B(?(3770)???_c1)=(18.0±3.3±2.5)??pb and branching fraction B(?(3770)???_c1)=(2.8±0.5±0.4)×10^-3. We set 90% C.L. upper limits for the transition to ?_c2 (?_c0): ?×B<5.7??pb (<282??pb) and B<0.9×10^-3 (<44×10^-3). We also determine ?(?(3770)???_c1)/?(?(3770)??⁺?^-J/?)=1.5±0.3±0.3 (>1.0 at 90% C.L.), which bears upon the interpretation of X(3872).

This paper describes a measurement of the top quark mass, M_top, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/antitop (tt? ) pairs in pp? collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318??pb^-1. We use the tt? candidates in the ?lepton+jets? decay channel, requiring at least one jet identified as a b quark by finding a displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of M_top per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 tt? candidates observed in the data, with 9.2 events expected from background, we measure the top quark mass to be 173.2+2.6 / -2.4(stat.)±3.2(syst.)??GeV/c², or 173.2+4.1 / -4.0??GeV/c².

We have studied the effects of chirped femtosecond laser pulses on the formation of ultracold molecules in a Rb magneto-optical trap. We have found that application of chirped femtosecond pulses suppressed the formation of ⁸⁵Rb₂ and ⁸⁷Rb₂ a?³?_u⁺ molecules in contrast to comparable nonchirped pulses, cw illumination, and background formation rates. Variation of the amount of chirp indicated that this suppression is coherent in nature, suggesting that coherent control is likely to be useful for manipulating the dynamics of ultracold quantum molecular gases.

We searched for scalar bottom quarks in 156??pb^-1 of p? p collisions at sqrt[s]=1.96??TeV recorded by the Collider Detector at Fermilab II experiment at the Tevatron. Scalar bottom quarks can be produced from gluino decays in R-parity conserving models of supersymmetry when the mass of the gluino exceeds that of the scalar bottom quark. Then, a scalar bottom quark can decay into a bottom quark and a neutralino. To search for this scenario, we investigated events with large missing transverse energy and at least three jets, two or more of which were identified as containing a secondary vertex from the hadronization of b quarks. We found four candidate events, where 2.6±0.7 are expected from standard model processes, and placed 95% confidence level lower limits on gluino and scalar bottom quark masses of up to 280 and 240??GeV/c², respectively.

Using data collected with the CLEO detector operating at the CESR e⁺e^- collider at sqrt[s]=3.97?4.26??GeV, we investigate 15 charmonium decay modes of the ?(4040), ?(4160), and Y(4260) resonances. We confirm, at 11? significance, the BABAR Y(4260)??⁺?^-J/? discovery, make the first observation of Y(4260)??⁰?⁰J/? (5.1?), and find the first evidence for Y(4260)?K⁺K^-J/? (3.7?). We measure e⁺e^- cross sections at sqrt[s]=4.26??GeV as ?(?⁺?^-J/?)=58_-10⁺¹²±4??pb, ?(?⁰?⁰J/?)=23_-8⁺¹²±1??pb, and ?(K⁺K^-J/?)=9_-5⁺⁹±1??pb, in which the uncertainties are statistical and systematic, respectively. Upper limits are placed on other decay rates from all three resonances.

We report a measurement of the top-quark mass using events collected by the CDF II detector from pp? collisions at sqrt[s]=1.96??TeV at the Fermilab Tevatron. We calculate a likelihood function for the top-quark mass in events that are consistent with tt? ?b? ?^-?? _?b?^?+?_?^? decays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340??pb^-1 of integrated luminosity, yielding a top-quark mass M_t=165.2±6.1(stat)±3.4(syst)??GeV/c². This first application of a matrix-element technique to tt? ?b?⁺?_?b? ?^?-?? _?^? decays gives the most precise single measurement of M_t in dilepton events. Combined with other CDF run II measurements using dilepton events, we measure M_t=167.9±5.2(stat)±3.7(syst)??GeV/c².

Using 420??pb^-1 of data collected on the ?(5S) resonance with the CLEO III detector, we reconstruct B mesons in 25 exclusive decay channels to measure or set upper limits on the decay rate of ?(5S) into B meson final states. We measure the inclusive B cross section to be ?(?(5S)?BB? (X))=(0.177±0.030±0.016)??nb and make the first measurements of the production rates of ?(?(5S)?B^*B? ^*)=(0.131±0.025±0.014)??nb and ?(?(5S)?BB? ^*)=(0.043±0.016±0.006)??nb, respectively. We set 90% confidence level limits of ?(?(5S)?BB? )<0.038??nb, ?(?(5S)?B^(*)B? ^(*)?)<0.055??nb and ?(?(5S)?BB? ??)<0.024??nb. We also extract the most precise value of the B_s^* mass to date, M(B_s^*)=(5411.7±1.6±0.6)??MeV/c².

We study the quantum mechanical correlation between two identical neutralinos in the decays of minimal supersymmetric standard model (MSSM) scalar tau (stau) pair produced in e⁺e^- annihilation. Generally, the decay products of scalar (spinless) particles are not correlated. We show that a correlation between two neutralinos appears near pair production threshold, due to a finite stau width and mixing of the staus and/or neutralinos, and because the neutralinos are Majorana. Because the correlation is significant only in a specific kinematical configuration, it can be observed only in supersymmetric models where the neutralino momenta can be kinematically reconstructed, such as in models with R-parity violation.

The two-photon width of ?_c2(³P₂) state of charmonium has been measured using 14.4??fb^-1 of e⁺e^- data taken at sqrt[s]=9.46?11.30??GeV with the CLEO III detector. The ??-fusion reaction studied is e⁺e^-?e⁺e^-??, ????_c2??J/???e⁺e^-(?⁺?^-). We measure ?_??(?_c2)B(?_c2??J/?)B(J/??e⁺e^-+?⁺?^-)=13.2±1.4(stat)±1.1(syst)??eV, and obtain ?_??(?_c2)=559±57(stat)±48(syst)±36(br)??eV. This result is in excellent agreement with the result of ??-fusion measurement by Belle and is consistent with that of the p? p??_c2??? measurement, when they are both reevaluated using the recent CLEO result for the radiative decay ?_c2??J/?.