Hadron multiplicities, pT-spectra and net-baryon number in central Pb+Pb collisions at the LHC

We compute the initial energy density and net baryon number density in 5% most central Pb+Pb collisions at $\sqrt s=5.5$ TeV from pQCD + (final state) saturation, and describe the evolution of the produced system with boost-invariant transversely expanding hydrodynamics. In addition to the total multiplicity at midrapidity, we give predictions for the multiplicity of charged hadrons, pions, kaons and (anti)protons, for the total transverse energy and net-baryon number, as well as for the $p_T$-spectrum of charged hadrons, pions and kaons. We also predict the region of applicability of hydrodynamics by comparing these results with high-$p_T$ hadron spectra computed from pQCD and energy losses.Comment: 2 pages, 2 figures, to be presented at the workshop "Heavy Ion Collisions at the LHC: Last Call for Predictions" at CERN 29 May - 2 Jun

On Lorentz Invariance, Spin-Charge Separation And SU(2) Yang-Mills Theory

Previously it has been shown that in spin-charge separated SU(2) Yang-Mills theory Lorentz invariance can become broken by a one-cocycle that appears in the Lorentz boosts. Here we study in detail the structure of this one-cocycle. In particular we show that its non-triviality relates to the presence of a (Dirac) magnetic monopole bundle. We also explicitely present the finite version of the cocycle.Comment: 4 page

Transverse Spectra of Hadrons in Central AAAA Collisions at RHIC and LHC from pQCD+Saturation+Hydrodynamics and from pQCD+Energy Losses

We study the transverse spectra of hadrons in nearly central $AA$ collisions at RHIC and LHC in a broad transverse momentum range Low-$p_T$ spectra are calculated by using boost-invariant hydrodynamics with initial energy and net-baryon densities from the EKRT pQCD+saturation model. High-$p_T$ spectra are obtained from pQCD jet calculation including the energy loss of the parton in the matter prior to its fragmentation to final hadrons.Comment: 4 pages, 2 figures, proceedings for Quark Matter 200

Dynamical Symmetry Breaking in Planar QED

We investigate (2+1)-dimensional QED coupled with Dirac fermions both at zero and finite temperature. We discuss in details two-components (P-odd) and four-components (P-even) fermion fields. We focus on P-odd and P-even Dirac fermions in presence of an external constant magnetic field. In the spontaneous generation of the magnetic condensate survives even at infinite temperature. We also discuss the spontaneous generation of fermion mass in presence of an external magnetic field.Comment: 34 pages, 8 postscript figures, final version to appear on J. Phys.

Heat Bath Particle Number Spectrum

We calculate the number spectrum of particles radiated during a scattering into a heat bath using the thermal largest-time equation and the Dyson-Schwinger equation. We show how one can systematically calculate {d}/{d\omega} to any order using modified real time finite-temperature diagrams. Our approach is demonstrated on a simple model where two scalar particles scatter, within a photon-electron heat bath, into a pair of charged particles and it is shown how to calculate the resulting changes in the number spectra of the photons and electrons.Comment: 29 pages, LaTeX; 14 figure

Singlet-assisted electroweak phase transition at two loops

We investigate the electroweak phase transition in the real-singlet extension of the Standard Model at two-loop level, building upon existing one-loop studies. We calculate the effective potential in the high-temperature approximation and detail the required resummations at two-loop order. In typical strongtransition scenarios, we find deviations of order 20%-50% from one-loop results in transition strength and critical temperature for both one- and two-step phase transitions. For extremely strong transitions, the discrepancy with one-loop predictions is even larger, presumably due to sizable scalar couplings in the tree-level potential. Along the way, we obtain a dimensionally reduced effective theory applicable for nonperturbative lattice studies of the model.Peer reviewe

AND Protocols Using Only Uniform Shuffles

Secure multi-party computation using a deck of playing cards has been a subject of research since the "five-card trick" introduced by den Boer in 1989. One of the main problems in card-based cryptography is to design committed-format protocols to compute a Boolean AND operation subject to different runtime and shuffle restrictions by using as few cards as possible. In this paper, we introduce two AND protocols that use only uniform shuffles. The first one requires four cards and is a restart-free Las Vegas protocol with finite expected runtime. The second one requires five cards and always terminates in finite time.Comment: This paper has appeared at CSR 201

Dynamical freeze-out condition in ultrarelativistic heavy ion collisions

We determine the decoupling surfaces for the hydrodynamic description of heavy ion collisions at RHIC and LHC by comparing the local hydrodynamic expansion rate with the microscopic pion-pion scattering rate. The pion $p_T$ spectra for nuclear collisions at RHIC and LHC are computed by applying the Cooper-Frye procedure on the dynamical-decoupling surfaces, and compared with those obtained from the constant-temperature freeze-out surfaces. Comparison with RHIC data shows that the system indeed decouples when the expansion rate becomes comparable with the pion scattering rate. The dynamical decoupling based on the rates comparison also suggests that the effective decoupling temperature in central heavy ion collisions remains practically unchanged from RHIC to LHC.Comment: 7 pages, 9 figure

Elliptic flow in nuclear collisions at the Large Hadron Collider

We use perfect-fluid hydrodynamical model to predict the elliptic flow coefficients in Pb + Pb collisions at the Large Hadron Collider (LHC). The initial state for the hydrodynamical calculation for central $A + A$ collisions is obtained from the perturbative QCD + saturation (EKRT) model. The centrality dependence of the initial state is modeled by the optical Glauber model. We show that the baseline results obtained from the framework are in good agreement with the data from the Relativistic Heavy Ion Collider (RHIC), and show predictions for the $p_T$ spectra and elliptic flow of pions in Pb + Pb collisions at the LHC. Also mass and multiplicity effects are discussed.Comment: 11 pages, 10 figure