93,221 research outputs found
Universal scaling of non-equilibrium critical fluctuations from Langevin dynamics of model A
Within the framework of the Kibble-Zurek Mechanism, we investigate the
universal behavior of the non-equilibrium critical fluctuations, using the
Langevin dynamics of model A. With properly located typical time, length and
angle scales, \tau_{\mbox{KZ}}, l_{\mbox{KZ}}, and \theta_{\mbox{KZ}},
the constructed functions
\bar{f}_n((\tau-\tau_c)/\tau_{\mbox{KZ}},\theta_{\mbox{KZ}}) (n=1...4) for
the cumulants of the sigma field show universal behavior near the critical
point, which are independent from some non-universal factors, such as the
relaxation time or the evolution trajectory.Comment: 6 pages, 3 figures, CPOD 2017 proceeding
R\'enyi entropy of locally excited states with thermal and boundary effect in 2D CFTs
We study R\'enyi entropy of locally excited states with considering the
thermal and boundary effects respectively in two dimensional conformal field
theories (CFTs). Firstly we consider locally excited states obtained by acting
primary operators on a thermal state in low temperature limit. The R\'enyi
entropy is summation of contribution from thermal effect and local excitation.
Secondly, we mainly study the R\'enyi entropy of locally excited states in 2D
CFT with a boundary. We show that the evolution of R\'enyi entropy does not
depend on the choice of boundary conditions and boundary will change the time
evolution of R\'enyi entropy. Moreover, in 2D rational CFTs with a boundary, we
show that the R\'enyi entropy always coincides with the log of quantum
dimension of the primary operator during some periods of the evolution. We make
use of a quasi-particle picture to understand this phenomenon. In terms of
quasi-particle interpretation, the boundary behaves as an infinite potential
barrier which reflects any energy moving towards the boundary.Comment: Published versio
Dynamical fluctuations in critical regime and across the 1st order phase transition
In this proceeding, we study the dynamical evolution of the sigma field
within the framework of Langevin dynamics. We find that, as the system evolves
in the critical regime, the magnitudes and signs of the cumulants of sigma
field, and , can be dramatically different from the equilibrated
ones due to the memory effects near . For the dynamical evolution across
the 1st order phase transition boundary, the supercooling effect leads the
sigma field to be widely distributed in the thermodynamical potential, which
largely enhances the cumulants , correspondingly.Comment: 4 pages, 2 figures, proceedings for Quark Matter 201
Entanglement Entropy for Descendent Local Operators in 2D CFTs
We mainly study the R\'enyi entropy and entanglement entropy of the states
locally excited by the descendent operators in two dimensional conformal field
theories (CFTs). In rational CFTs, we prove that the increase of entanglement
entropy and R\'enyi entropy for a class of descendent operators, which are
generated by onto the primary operator,
always coincide with the logarithmic of quantum dimension of the corresponding
primary operator. That means the R\'enyi entropy and entanglement entropy for
these descendent operators are the same as the ones of their corresponding
primary operator. For 2D rational CFTs with a boundary, we confirm that the
R\'enyi entropy always coincides with the logarithmic of quantum dimension of
the primary operator during some periods of the evolution. Furthermore, we
consider more general descendent operators generated by on the primary
operator. For these operators, the entanglement entropy and R\'enyi entropy get
additional corrections, as the mixing of holomorphic and anti-holomorphic
Virasoro generators enhance the entanglement. Finally, we employ perturbative
CFT techniques to evaluate the R\'enyi entropy of the excited operators in
deformed CFT. The R\'enyi and entanglement entropies are increased, and get
contributions not only from local excited operators but also from global
deformation of the theory.Comment: 30 pages, 2 figures; minor revion, references adde
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