119303364
Cold electroweak baryogenesis in the two Higgs-doublet model
A bstractWe perform the first investigation of cold electroweak baryogenesis in the two Higgs-doublet model (2HDM). The electroweak symmetry breaking transition is assumed to occur through a spinodal instability from a super-cooled initial state. We consider the creation of net Chern-Simons number, which through the axial anomaly is equivalent to a baryon asymmetry. CP violation is explicit in the scalar potential, but only in combination with P-violation is it possible for an asymmetry to be generated. This is introduced through the leading C-and P-breaking, but CP invariant, term expected to arise upon integrating out the fermions in the theory. We perform real-time lattice simulations of the transition, and find the coefficient of this term required for successful baryogenesis.
17627816
Exclusive vs. diffractive vector meson production in DIS at small x or off nuclei
The diffractive production of vector mesons in deep inelastic scattering (DIS) is calculated in the McLerran-Venugopalan model. This is relevant when large parton densities are probed by the virtual photon, as is the case at small Bjorken x or in DIS off nuclei. We investigate differences between the exclusive production (when the target doesn't break up) which dominates at small momentum transfer squared |t|, and the diffractive production (when the target scatters inelastically) which dominates at large |t|.
119193432
On holographic thermalization and gravitational collapse of massless scalar fields
A bstractIn this paper we study thermalization in a strongly coupled system via AdS/CFT. Initially, the energy is injected into the system by turning on a spatially homogenous scalar source coupled to a marginal composite operator. The thermalization process is studied by numerically solving Einstein’s equations coupled to a massless scalar field in the Poincare patch of AdS5. We define a thermalization time tT on the AdS side, which has an interpretation in terms of a spacelike Wilson loop $ \left\langle {W\left( {l\tilde{-}\frac{1}{T}} \right)} \right\rangle $ in CFT. Here T is the thermal equilibrium temperature. We study both cases with the source turned on in short $ \left( {\varDelta t\lesssim \frac{1}{T}} \right) $ and long $ \left( {\varDelta t\gtrsim \frac{1}{T}} \right) $ durations. In the former case, the thermalization time $ {t_T}=\frac{gt }{T}\lesssim \frac{1}{T} $ and the coefficient $ {g_t}\tilde{-}0.73 $ in the limit $ \varDelta t\lesssim \frac{0.02 }{T} $. In the latter case, we find double- and multiple-collapse solutions, which may be interpreted as the gravity duals of two- or multi-stage thermalization in CFT. In all the cases our results indicate that such a strongly coupled system thermalizes in a typical time scale $ {t_T}\tilde{-}\frac{O(1) }{T} $.
119185980
Shock wave collisions in AdS5: approximate numerical solutions
We numerically study the evolution of a boost-invariant N=4 SYM medium using AdS/CFT. We consider a toy model for the collision of gravitational shock waves, finding that the energy density first increases, reaches a maximum and then starts to decrease, matching hydrodynamics for late times. For the initial conditions we consider, the hydrodynamic scale governing the late time behaviour is to very good approximation determined by the area of the black hole horizon at initial times. Our results provide a toy model for the early time evolution of the bulk system in heavy-ion collisions at RHIC and the LHC.
118497947
Properties of the Boltzmann equation in the classical approximation
We study the Boltzmann equation with elastic point-like scalar interac-tions in two different versions of the the classical approximation. Although solving numerically the Boltzmann equation with the unapproximated col-lision term poses no problem, this allows one to study the effect of the ultraviolet cutoff in these approximations. This cutoff dependence in the classical approximations of the Boltzmann equation is closely related to the non-renormalizability of the classical statistical approximation of the underlying quantum field theory. The kinetic theory setup that we con-sider here allows one to study in a much simpler way the dependence on the ultraviolet cutoff, since one has also access to the non-approximated result for comparison.
118447664
Nonrenormalizability of the classical statistical approximation
In this paper, we discuss questions related to the renormalizability of the classical statistical approximation, an approximation scheme that has been used recently in several studies of out-of-equilibrium problems in Quantum Field Theory. Although the ultraviolet power counting in this approximation scheme is identical to that of the unapproximated quantum field theory, this approximation is not renormalizable. The leading cause of this non-renormalizability is the breakdown of Weinberg's theorem in this approximation. We also discuss some practical implications of this negative result for simulations that employ this approximation scheme, and we speculate about a possible modification of the classical statistical approximation in order to systematically subtract the leading residual divergences.
196095135
Simulation of Central and Dimuon Events in the ALICE DAQ System.
59844874
Simulation of the ALICE DAQ System with GALSIM