18713583
Lattice QCD calculations for the physical equation of state
In this report we consider the numerical simulations at finite temperature using lattice QCD data for the computation of the thermodynamical quantities including the pressure, energy density and the entropy density. These physical quantities can be related to the equation of state for quarks and gluons. We shall apply the lattice data to the evaluation of the specific structure of the gluon and quark condensates at finite temperature in relation to the deconfinement and chiral phase transitions. Finally we mention the quantum nature of the phases at lower temperatures.
18890188
The speed of sound in hadronic matter
We calculate the speed of sound cs in an ideal gas of resonances, whose mass spectrum is assumed to have the Hagedorn form ρ(m)∼m−aexp {bm}, which leads to singular behavior at the critical temperature Tc=1/b. With a=4 the pressure and the energy density remain finite at Tc, while the specific heat diverges there. As a function of the temperature, the corresponding speed of sound initially increases similarly to that of an ideal pion gas, until near Tc resonance effects dominate, which causes cs to vanish as (Tc−T)1/4. In order to compare this result to the physical resonance gas models, we introduce an upper cut-off M in the resonance mass integration. Although the truncated form still decreases somewhat in the region around Tc, the actual critical behavior in these models is no longer present.
6925871
The effects of coloured quark entropy on the bag pressure
We study the effects of the ground state entropy of coloured quarks upon the bag pressure at low temperatures. The vacuum expectation values of the quark and gluon fields are used to express the interactions in the QCD ground state in the limit of low temperatures and chemical potentials. Apparently, the inclusion of this entropy in the equation of state provides the hadron constituents with an additional heat which causes a decrease in the effective latent heat inside the hadronic bag and consequently decreases the non-perturbative bag pressure. We have considered two types of baryonic bags, Δ and Ω−. In both cases we have found that the bag pressure decreases with the temperature. On the other hand, when the coloured quark ground state entropy is not considered, the bag pressure as conventionally believed remains constant for finite temperature.
118943299
THE PHYSICAL PHASE OF DIMENSIONALLY REDUCED GAUGE-THEORIES
We investigate the relationship between the high-temperature deconfined phase of the SU(2) gauge theory to the phases of the corresponding three-dimensional adjoint Higgs model. For various temperatures we simulate the effective theory in a neighbourhood of the physical states, that is of those values of the coupling constants that describe the infrared behaviour of the four-dimensional theory and which have been calculated by applying dimensional reduction techniques. We show that the physical points belong to the confined phase of the SU(2) adjoint Higgs model.
116060740
THERMODYNAMICS OF A RELATIVISTIC FERMI GAS IN A STRONG MAGNETIC-FIELD
On etudie les proprietes thermodynamiques dans l'ensemble grand canonique pour un gaz ideal de spins-Y 2 relativiste contenant a la fois particules et antiparticules en presence d'un champ magnetique constant fort
115316476
Limiting particle density of a relativistic Fermi gas in a magnetic field
On etudie la densite totale de particules dans l'ensemble grand canonique d'un gaz de Fermi relativiste constitue de particules de spins 1/2 en presence d'un champ magnetique externe homogene constant
16971342
Entropy for SU(3)c quark states
We discuss the quantum state structure using the standard model for three colored quarks in the fundamental representations of SU(3)c making up the singlet ground state of the hadrons. This allows us to calculate a finite von Neumann entropy from the quantum reduced density matrix, which we explicitly evaluate for the quarks in a model for the meson and baryon states.
122908637
Gamma gamma physics at LEP-2: Experimental possibilities
QCD tests and studies of heavy quark production and decay will be the most important parts of the Yf programme at LEP2. This discussion assesses the promise of a range of possible topics of study, comparing with what might be achieved at LEP1 , TRISTAN or lower energy colliders.
41665346
Holographic bubble chambers
122633316
Inelastic excitation of normal parity levels in 208Pb by 135 MeV protons
Abstract New cross section data for the inelastic excitation of normal parity levels in 208 Pb with spins ranging from J =2 to J =2 are reported. The data are examined in terms of the collective model including deformed spin-orbit coupling. The experimental differential cross sections exhibit a striking transition from central dominated shapes to spin-orbit dominated shapes at J =8.
47376724
Instrumentation of the very forward region of a linear collider detector
The very forward region of a detector at a linear e/sup +/e/sup -/ collider is a particularly challenging area for instrumentation. In the TESLA detector, two calorimeters, BeamCal (Beam Calorimeter) and LumiCal (Luminosity Calorimeter) are planned. The BeamCal is positioned just adjacent to the beampipe. It will be hit by beamstrahlung remnants giving a deposition of several tens of TeV per bunch crossing. The distribution of this energy will be measured to assist in tuning the beams. Single high-energy electrons will be identified and measured. High-energy electron identification is particularly important to veto backgrounds to new particle searches. Several technological options for BeamCal are discussed. Monte Carlo simulations are presented for a diamond/tungsten sandwich structure and compared to results obtained for a heavy element crystal calorimeter. First, tests of sensors are described. The LumiCal will measure larger polar angles than the BeamCal. It will provide a high-precision (O(10/sup -4/)) luminosity measurement from Bhabha scattering. Monte Carlo simulations to optimize the shape and the structure of the calorimeter are presented.