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Full-Text Articles in Physical Sciences and Mathematics
The Two-Dimensional Bose-Einstein Condensate, Jp Fernandez, Wj Mullin
The Two-Dimensional Bose-Einstein Condensate, Jp Fernandez, Wj Mullin
Physics Department Faculty Publication Series
We study the Hartree–Fock–Bogoliubov mean-field theory as applied to a two-dimensional finite trapped Bose gas at low temperatures and find that, in the Hartree–Fock approximation, the system can be described either with or without the presence of a condensate; this is true in the thermodynamic limit as well. Of the two solutions, the one that includes a condensate has a lower free energy at all temperatures. However, the Hartree–Fock scheme neglects the presence of phonons within the system, and when we allow for the possibility of phonons we are unable to find condensed solutions; the uncondensed solutions, on the other …
Rare Charm Decays, Eugene Golowich
Rare Charm Decays, Eugene Golowich
Physics Department Faculty Publication Series
This paper is a written version of a talk on rare (FCNC) D meson decays as presented at the Electroweak Moriond 2002. The presentation proceeds in two parts. We first consider Standard Model predictions, taking into account both short-distance and long distance effects. Then several New Physics options (e.g. supersymmatry, strong dynamics, extra large dimenions, etc) are considered.
Comment On ‘Analysis Of O(P2) Corrections To Hðð|Q7,8|Ki’, Vincenzo Cirigliano, Eugene Golowich
Comment On ‘Analysis Of O(P2) Corrections To Hðð|Q7,8|Ki’, Vincenzo Cirigliano, Eugene Golowich
Physics Department Faculty Publication Series
We extend in several respects our earlier work on O(p2) corrections to the matrix elements of the electroweak penguin operator Oewp. First, to facilitate comparison with certain lattice studies we calculate O(p2) corrections to 〈π|Oewp|K〉 in the SU(3) limit of equal light quark masses. Next, we demonstrate how an apparent disagreement in the literature regarding whether higher order chiral contributions increase or decrease 〈(ππ)I=2|Oewp|K〉 is simply a consequence of how the leading order chiral amplitude is defined. Finally, we address an aspect of the ε′/ε problem by estimating O(p2) corrections to recent determinations of 〈(ππ)I=2|Q7,8|K〉 which were carried out in …
Two-Dimensional Weakly Interacting Bose Gas In The Fluctuation Region, Nikolai Prokof'ev, Boris Svistunov
Two-Dimensional Weakly Interacting Bose Gas In The Fluctuation Region, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We study the crossover between the mean-field and critical behavior of the two-dimensional Bose gas throughout the fluctuation region of the Berezinskii-Kosterlitz-Thouless phase transition point. We argue that this crossover is described by universal (for all weakly interacting |ψ|4 models) relations between thermodynamic parameters of the system, including superfluid and quasicondensate densities. We establish these relations with high-precision Monte Carlo simulations of the classical |ψ|4 model on a lattice, and check their asymptotic forms against analytic expressions derived on the basis of the mean-field theory.
Self-Trapping Of Polarons In The Rashba-Pekar Model, A Mishchenko, N Nagaosa, Nikolai Prokof'ev, A Sakamoto, B Svistunov
Self-Trapping Of Polarons In The Rashba-Pekar Model, A Mishchenko, N Nagaosa, Nikolai Prokof'ev, A Sakamoto, B Svistunov
Physics Department Faculty Publication Series
We performed a quantum Monte Carlo study of the exciton-polaron model which features the self-trapping phenomenon when the coupling strength and/or particle momentum is varied. Accurate data for energy, effective mass, the structure of the polaronic cloud, dispersion law, and spectral function became available throughout the crossover region. We observed that self-trapping cannot be reduced to hybridization of two states with different lattice deformation, and that at least three states are involved in the crossover from light- to heavy-mass regimes.
A Positive Energy Theorem For Asymptotically De Sitter Spacetimes, David Kastor, Jennie Traschen
A Positive Energy Theorem For Asymptotically De Sitter Spacetimes, David Kastor, Jennie Traschen
Physics Department Faculty Publication Series
We construct a set of conserved charges for asymptotically de Sitter spacetimes that correspond to asymptotic conformal isometries. The charges are given by boundary integrals at spatial infinity in the flat cosmological slicing of de Sitter. Using a spinor construction, we show that the charge associated with conformal time translations is necessarily positive and hence may provide a useful definition of energy for these spacetimes. A similar spinor construction shows that the charge associated with the time translation Killing vector of de Sitter in static coordinates has both positive and negative definite contributions. For Schwarzschild–de Sitter the conformal energy we …
Allowed Eta-Decay Modes And Chiral Symmetry, Br Holstein
Allowed Eta-Decay Modes And Chiral Symmetry, Br Holstein
Physics Department Faculty Publication Series
Recently, the development of chiral perturbation theory has allowed the generation of rigorous low-energy theorems for various hadronic processes based only on the chiral invariance of the underlying QCD Lagrangian. Such techniques are highly developed and well-tested in the domain of pionic and kaonic reactions. In this note we point out that with the addition of a few additional and reasonable assumptions similar predictive power is available for processes involving the eta meson
Rare Charm Decays In The Standard Model And Beyond, G Burdman, E Golowich, J Hewett, S Pakvasa
Rare Charm Decays In The Standard Model And Beyond, G Burdman, E Golowich, J Hewett, S Pakvasa
Physics Department Faculty Publication Series
We perform a comprehensive study of a number of rare charm decays, incorporating the first evaluation of the QCD corrections to the short distance contributions, as well as examining the long range effects. For processes mediated by the c⃗ul+l- transitions, we show that sensitivity to short distance physics exists in kinematic regions away from the vector meson resonances that dominate the total rate. In particular, we find that D⃗πl+l- and D⃗ρl+l- are sensitive to nonuniversal soft-breaking effects in the minimal supersymmetric standard model with R-parity conservation. We separately study the sensitivity of these modes to R-parity violating effects and derive …
Revealing The Superfluid–Mott-Insulator Transition In An Optical Lattice, V Kashurnikov, Nikolai Prokof'ev, Boris Svistunov
Revealing The Superfluid–Mott-Insulator Transition In An Optical Lattice, V Kashurnikov, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We study (by an exact numerical scheme) the single-particle density matrix of ∼103 ultracold atoms in an optical lattice with a parabolic confining potential. Our simulation is directly relevant to the interpretation and further development of the recent pioneering experiment by Greiner et al., Nature, (London) 415, 39 (2002). In particular, we show that restructuring of the spatial distribution of the superfluid component when a domain of Mott-insulator phase appears in the system, results in a fine structure of the particle momentum distribution. This feature may be used to locate the point of the superfluid–Mott-insulator transition.
Quantum Corrections To The Reissner-Nordstrom And Kerr-Newman Metrics, Jf Donoghue, Br Holstein, B Garbrecht, T Konstandin
Quantum Corrections To The Reissner-Nordstrom And Kerr-Newman Metrics, Jf Donoghue, Br Holstein, B Garbrecht, T Konstandin
Physics Department Faculty Publication Series
We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of non-analytic pieces Image , q2log(−q2), etc. in the form factors of the energy–momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner–Nordström and Kerr–Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order Gαplanck constant over two pi/mr3.
Decay Pi(0)->Gamma Gamma To Next To Leading Order In Chiral Perturbation Theory, Jl Goity, Am Bernstein, Br Holstein
Decay Pi(0)->Gamma Gamma To Next To Leading Order In Chiral Perturbation Theory, Jl Goity, Am Bernstein, Br Holstein
Physics Department Faculty Publication Series
The π0→γγ decay width is analyzed within the combined framework of chiral perturbation theory and the 1/Nc expansion up to O(p6) and O(p4×1/Nc) in the decay amplitude. The η′ is explicitly included in the analysis. It is found that the decay width is enhanced by about 4.5% due to the isospin-breaking induced mixing of the pure U(3) states. This effect, which is of leading order in low energy expansion, is shown to persist nearly unchanged at next to leading order. The chief prediction with its estimated uncertainty is Γπ0→γγ=8.10±0.08eV. This prediction at the 1% level makes the upcoming precision measurement …
Electroweak Radiative Corrections To Parity-Violating Electroexcitation Of The Delta, Sl Zhu, Cm Maekawa, G Sacco, Br Holstein, Mj Ramsey-Musolf
Electroweak Radiative Corrections To Parity-Violating Electroexcitation Of The Delta, Sl Zhu, Cm Maekawa, G Sacco, Br Holstein, Mj Ramsey-Musolf
Physics Department Faculty Publication Series
We analyze the degree to which parity-violating (PV) electroexcitation of the Δ(1232) resonance may be used to extract the weak neutral axial vector transition form factors. We find that the axial vector electroweak radiative corrections are large and theoretically uncertain, thereby modifying the nominal interpretation of the PV asymmetry in terms of the weak neutral form factors. We also show that, in contrast with the situation for elastic electron scattering, the axial N→Δ PV asymmetry does not vanish at the photon point as a consequence of a new term entering the radiative corrections. We argue that an experimental determination of …
Long Distance Regularization In Chiral Perturbation Theory With Decuplet Fields, B Borasoy, Br Holstein, R Lewis, Ppa Ouimet
Long Distance Regularization In Chiral Perturbation Theory With Decuplet Fields, B Borasoy, Br Holstein, R Lewis, Ppa Ouimet
Physics Department Faculty Publication Series
We investigate the use of long distance regularization in SU(3) baryon chiral perturbation theory with decuplet fields. The one-loop decuplet contributions to the octet baryon masses, axial-vector couplings, S-wave nonleptonic hyperon decays and magnetic moments are evaluated in a chirally consistent fashion by employing a cutoff to implement long distance regularization. The convergence of the chiral expansions of these quantities is improved compared to the dimensionally regularized version which indicates that the propagation of Goldstone bosons over distances smaller than a typical hadronic size, which is beyond the regime of chiral perturbation theory but included by dimensional regularization, is removed …