681 research outputs found
Density profiles and collective modes of a Bose-Einstein condensate with light-induced spin-orbit coupling
The phases of a Bose-Einstein condensate (BEC) with light-induced spin-orbit
coupling (SOC) are studied within the mean-field approximation. The mixed BEC
phase, in which the system condenses in a superposition of two plane wave
states, is found to be stable for sufficiently small light-atom coupling,
becoming unstable in a continuous fashion with increasing light-atom coupling.
The structure of the phase diagram at fixed chemical potential for bosons with
SOC is shown to imply an unusual density dependence for a trapped mixed BEC
phase, with the density of one dressed spin state increasing with increasing
radius, providing a unique experimental signature of this state. The collective
Bogoliubov sound mode is shown to also provide a signature of the mixed BEC
state, vanishing as the boundary to the regime of phase separation is
approached.Comment: 9 pages, 4 figures. Published Versio
A self-consistent Hartree-Fock approach for interacting bosons in optical lattices
A theoretical study of interacting bosons in a periodic optical lattice is
presented. Instead of the commonly used tight-binding approach (applicable near
the Mott insulating regime of the phase diagram), the present work starts from
the exact single-particle states of bosons in a cubic optical lattice,
satisfying the Mathieu equation, an approach that can be particularly useful at
large boson fillings. The effects of short-range interactions are incorporated
using a self-consistent Hartree-Fock approximation, and predictions for
experimental observables such as the superfluid transition temperature,
condensate fraction, and boson momentum distribution are presented.Comment: 12 pages, 15 figure file
Branching ratios and direct CP asymmetries in decays
We study the two-body hadronic decays, where () denotes a
pseudoscalar (vector) meson, in the factorization-assisted
topological-amplitude approach proposed in our previous work. This approach is
based on the factorization of short-distance and long-distance dynamics into
Wilson coefficients and hadronic matrix elements of four-fermion operators,
respectively, with the latter being parametrized in terms of several
nonperturbative quantities. We further take into account the -
mixing effect, which improves the global fit to the branching ratios involving
the and mesons. Combining short-distance dynamics associated
with penguin operators and the hadronic parameters determined from the global
fit to branching ratios, we predict direct asymmetries. In particular, the
direct asymmetries in the , , and decays are found to be of , which can be
observed at the LHCb or future Belle II experiment. We also predict the
asymmetry observables of some neutral meson decays.Comment: 16 pages, 2 figure
Perturbative QCD study of decays to a pseudoscalar meson and a tensor meson
We study two-body hadronic decays, with being a light
pseudoscalar (tensor) meson, in the perturbative QCD approach. The CP-averaged
branching ratios and the direct CP asymmetries of the modes are
predicted, where is the difference between the strange numbers of
final and initial states. We also define and calculate experimental observables
for the modes under the mixing, including CP
averaged branching ratios, time-integrated CP asymmetries, and the CP
observables , and . Results are compared to the ones in the literature, and to the ones, which indicate
considerable U-spin symmetry breaking. Our work provides theoretical
predictions for the decays for the first time, some of which will
be potentially measurable at future experiments.Comment: 6 pages, 1 figur
Charged lepton flavor violating Higgs decays at future colliders
After the discovery of the Higgs boson, several future experiments have been
proposed to study the Higgs boson properties, including two circular lepton
colliders, the CEPC and the FCC-ee, and one linear lepton collider, the ILC. We
evaluate the precision reach of these colliders in measuring the branching
ratios of the charged lepton flavor violating Higgs decays ,
and . The expected upper bounds on the
branching ratios given by the circular (linear) colliders are found to be
, and at 95\% CL, which are improved by
one to two orders compared to the current experimental bounds. We also discuss
the constraints that these upper bounds set on certain theory parameters,
including the charged lepton flavor violating Higgs couplings, the
corresponding parameters in the type-III 2HDM, and the new physics cut-off
scales in the SMEFT, in RS models and in models with heavy neutrinos.Comment: 20 pages, 2 figures (extend the CEPC study to the FCC-ee and the ILC,
and to match the published version
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