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Alessandro Papa

Publications and source records attributed to Alessandro Papa.

135 records · Page 8Linked to original sources
arXiv2006

The spectrum of massive excitations of 3d 3-state Potts model and universality

We consider the mass spectrum of the 3$d$ 3-state Potts model in the broken phase (a) near the second order Ising critical point in the temperature - magnetic field plane and (b) near the weakly first order transition point at zero magnetic field. In the case (a), we compare the mass spectrum with the prediction from universality of mass ratios in the 3$d$ Ising class; in the case (b), we determine a mass ratio to be compared with the corresponding one in the spectrum of screening masses of the (3+1)$d$ SU(3) pure gauge theory at finite temperature in the deconfined phase near the transition. The agreement in the comparison in the case (a) would represent a non-trivial test of validity of the conjecture of spectrum universality. A positive answer to the comparison in the case (b) would suggest the possibility to extend this conjecture to weakly first order phase transitions.

hep-lat↗
arXiv2006

QCD in the Regge limit: from gluon Reggeization to physical amplitudes

This paper is a brief survey of the Balitskii-Fadin-Kuraev-Lipatov (BFKL) approach for the description of hard or semi-hard processes in the so-called Regge limit of perturbative QCD. The starting point is a fundamental property of perturbative QCD, the gluon Reggeization. This property, combined with s-channel unitarity, allows to predict the growth in energy of the amplitude of hard or semi-hard processes with exchange of vacuum quantum numbers in the $t$-channel. When also the so-called impact factors of the colliding particles are known, then not only the behavior with the energy, but the complete amplitude can be determined. This was recently done, for the first time with next-to-leading order accuracy and for a process with colorless external particles, in the case of the electroproduction of two light vector mesons.

hep-ph↗
arXiv2005

QED_3 on a space-time lattice: a comparison between compact and noncompact formulation

Quantum electrodynamics in a (2+1)-dimensional space-time has been object of studies both as effective theory for the pseudogap phase of high-T_c superconductors and for the theoretical investigation of mechanisms of confinement in presence of matter fields. We discretize the theory using both compact and noncompact formulations, analyze the behavior of the chiral condensate and of the monopole density and compare them. Finally we draw some conclusions about the possible equivalence of the two lattice formulations.

hep-lat↗
arXiv2004

Finite temperature 2-color QCD for real and imaginary chemical potential

In this work we study the finite temperature SU(2) gauge theory with staggered fermions for real and imaginary chemical potential. We test the method of analytical continuation of Monte Carlo results obtained for imaginary chemical potential, by comparison with those obtained {\em directly} for real chemical potential.

hep-lat↗
arXiv2002

Finite-size scaling and deconfinement transition: the case of 4D SU(2) pure gauge theory

A recently introduced method for determining the critical indices of the deconfinement transition in gauge theories, already tested for the case of 3D SU(3) pure gauge theory, is applied here to 4D SU(2) pure gauge theory. The method is inspired by universality and based on the finite size scaling behavior of the expectation value of simple lattice operators, such as the plaquette. We obtain an accurate determination of the critical index $ν$, in agreement with the prediction of the Svetitsky-Yaffe conjecture.

hep-lat↗
arXiv2001

Finite-size scaling and deconfinement transition in gauge theories

A new method is proposed for determining the critical indices of the deconfinement transition in gauge theories, based on the finite-size scaling analysis of simple lattice operators, such as the plaquette. A precise determination of the critical index $ν$, in agreement with the prediction of the Svetitsky-Yaffe conjecture, is obtained for SU(3) gauge theory in (2+1)-dimension. Preliminary results for SU(2) in (3+1)-dimension are also given.

hep-lat↗
arXiv2000

Check of the Bootstrap Conditions for the Gluon Reggeization

The property of gluon Reggeization plays an essential role in the derivation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at high energy $\sqrt s$ in perturbative QCD. This property has been proved to all orders of perturbation theory in the leading logarithmic approximation and it is assumed to be valid also in the next-to-leading logarithmic approximation, where it has been checked only to the first three orders of perturbation theory. From $s$-channel unitarity, however, very stringent ``bootstrap'' conditions can be derived which, if fulfilled, leave no doubts that gluon Reggeization holds.

hep-ph↗