84,321 research outputs found
Dynamical recovery of SU(2) symmetry in the mass-quenched Hubbard model
We use non-equilibrium dynamical mean-field theory with iterative
perturbation theory as an impurity solver to study the recovery of
symmetry in real-time following a hopping integral parameter quench from a
mass-imbalanced to a mass-balanced single-band Hubbard model at half-filling. A
dynamical order parameter is defined to characterize the evolution
of the system towards symmetry. By comparing the momentum dependent
occupation from an equilibrium calculation (with the symmetric
Hamiltonian after the quench at an effective temperature) with the data from
our non-equilibrium calculation, we conclude that the symmetry
recovered state is a thermalized state. Further evidence from the evolution of
the density of states supports this conclusion. At the same time, we find the
order parameter in the weak Coulomb interaction regime undergoes an approximate
exponential decay. We numerically investigate the interplay of the relevant
parameters (initial temperature, Coulomb interaction strength, initial
mass-imbalance ratio) and their combined effect on the thermalization behavior.
Finally, we study evolution of the order parameter as the hopping parameter is
changed with either a linear ramp or a pulse. Our results can be useful in
strategies to engineer the relaxation behavior of interacting, quantum
many-particle systems.Comment: 8 pages, 6 figure
Partial Hasse invariants on splitting models of Hilbert modular varieties
Let be a totally real field of degree , and let be a prime number.
We construct partial Hasse invariants on the characteristic fiber of
the Pappas-Rapoport splitting model of the Hilbert modular variety for with
level prime to , extending the usual partial Hasse invariants defined over
the Rapoport locus. In particular, when ramifies in , we solve the
problem of lack of partial Hasse invariants. Using the stratification induced
by these generalized partial Hasse invariants on the splitting model, we prove
in complete generality the existence of Galois pseudo-representations attached
to Hecke eigenclasses of paritious weight occurring in the coherent cohomology
of Hilbert modular varieties , extending a previous result
of M. Emerton and the authors which required to be unramified in .Comment: 24 pages, refereed version, index changed from the previous versio
Globally Polarized Quark-gluon Plasma in Non-central A+A Collisions
Produced partons have large local relative orbital angular momentum along the
direction opposite to the reaction plane in the early stage of non-central
heavy-ion collisions. Parton scattering is shown to polarize quarks along the
same direction due to spin-orbital coupling. Such global quark polarization
will lead to many observable consequences, such as left-right asymmetry of
hadron spectra, global transverse polarization of thermal photons, dileptons
and hadrons. Hadrons from the decay of polarized resonances will have azimuthal
asymmetry similar to the elliptic flow. Global hyperon polarization is
predicted within different hadronization scenarios and can be easily tested.Comment: 4 pages in RevTex with 2 postscript figures, an erratum is added to
the final published versio
Photon-photon scattering: a tutorial
Long-established results for the low-energy photon-photon scattering, gamma
gamma --> gamma gamma, have recently been questioned. We analyze that claim and
demonstrate that it is inconsistent with experience. We demonstrate that the
mistake originates from an erroneous manipulation of divergent integrals and
discuss the connection with another recent claim about the Higgs decay into two
photons. We show a simple way of correctly computing the low-energy gamma gamma
scattering.Comment: 9 pages, 2 figures; v2: typographical errors corrected in eqs 1, 20,
and 21; ref. [23] adde
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