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We review recent work regarding the role of light scalar resonances at finite temperature for chiral symmetry and $U(1)_A$ restoration. The results obtained are based on unitarized Chiral Perturbation Theory and Ward Identities and are…

High Energy Physics - Phenomenology · Physics 2023-12-22 Angel Gómez Nicola , Jacobo Ruiz de Elvira , Andrea Vioque-Rodríguez

We investigate QCD with a large number of massless flavors with the aid of renormalization group flow equations. We determine the critical number of flavors separating the phases with and without chiral symmetry breaking in SU(Nc) gauge…

High Energy Physics - Phenomenology · Physics 2009-01-07 Holger Gies , Joerg Jaeckel

We discuss properties of thermal Quantum Chromodynamics obtained by means of lattice simulations with overlap fermions. This fermion discretisation preserves chiral symmetry at finite lattice spacing. We present details of the formulation…

High Energy Physics - Lattice · Physics 2025-10-30 Z. Fodor , A. Yu. Kotov , T. G. Kovacs , K. K. Szabo

We study the topological susceptibility in 2+1 flavor QCD above the chiral crossover transition temperature using Highly Improved Staggered Quark action and several lattice spacings, corresponding to temporal extent of the lattice,…

High Energy Physics - Lattice · Physics 2016-11-29 Peter Petreczky , Hans-Peter Schadler , Sayantan Sharma

We present results on both the restoration of the spontaneously broken chiral symmetry and the effective restoration of the anomalously broken U(1)_A symmetry in finite temperature QCD at zero chemical potential using lattice QCD. We employ…

We have studied the restoration of chiral symmetry in lattice QCD at the finite temperature transition from hadronic matter to a quark-gluon plasma. By measuring the screening masses of flavour singlet and non-singlet meson excitations, we…

High Energy Physics - Lattice · Physics 2007-05-23 J. -F. Lagae , D. K. Sinclair , J. B. Kogut

We investigate the topological susceptibility of the QCD vacuum with two flavours of dynamical staggered fermions on the lattice both at zero and finite temperature. At zero temperature we study the dependence of the signal on the fermion…

High Energy Physics - Lattice · Physics 2015-06-25 B. Alles , M. D'Elia , A. Di Giacomo

The $N_f$-flavour Schwinger Model on a finite space $0\leq x^1\leq L$ and subject to bag-type boundary-conditions at $x^1=0$ und $x^1=L$ is solved at finite temperature $T=1/\beta$. The boundary conditions depend on a real parameter…

High Energy Physics - Theory · Physics 2016-09-06 Stephan Dürr , Andreas Wipf

We reconsider constraints on the eigenvalue density of the Dirac operator in the chiral symmetric phase of 2 flavor QCD at finite temperature. To avoid possible ultra-violet(UV) divergences, we work on a lattice, employing the overlap Dirac…

High Energy Physics - Lattice · Physics 2013-05-30 Sinya Aoki , Hidenori Fukaya , Yusuke Taniguchi

We study again the phenomenon of charge fractionalization at finite temperature. Our calculations are done in a framework in which the connection between the induced fermion number and the chiral anomaly is manifest. We find that the…

High Energy Physics - Theory · Physics 2012-01-30 Yeong-Chuan Kao , Ming-Chiun Wu

We solve the long-standing problem concerning the fate of the chiral $U(1)_A$ symmetry in QCD-like theories at high temperature in the chiral limit. We introduce a simple instanton based random matrix model that precisely reproduces the…

High Energy Physics - Lattice · Physics 2023-12-15 Tamas G. Kovacs

It has been proposed, that the chiral continuum limit of 2-flavour QCD with Wilson fermions is brought about by a phase in which flavour and parity symmetry are broken spontaneously at finite lattice spacing. At finite temperature this…

High Energy Physics - Lattice · Physics 2007-05-23 F. Karsch , E. Laermann , M. Oevers , P. Schmidt

I discuss several topics in the applications of chiral symmetry at nonzero temperature, including: where the rho goes, disoriented chiral condensates, and the phase diagram for $QCD$ with $2+1$ flavors. (Based upon talks presented at the…

High Energy Physics - Phenomenology · Physics 2016-09-01 Robert D. Pisarski

We study the low-lying eigenmodes of the lattice overlap Dirac operator for SU(N) gauge theories with N=2,3,4 and 5 colours. We define a fermionic topological charge from the zero-modes of this operator and show that, as N grows, any…

High Energy Physics - Lattice · Physics 2009-11-07 Nigel Cundy , Michael Teper , Urs Wenger

We determine the topological susceptibility \chi_t in the topologically-trivial sector generated by lattice simulations of N_f = 2+1 QCD with overlap Dirac fermion, on a 16^3 x 48 lattice with lattice spacing ~ 0.11 fm, for five sea quark…

High Energy Physics - Lattice · Physics 2010-01-21 T. W. Chiu , S. Aoki , S. Hashimoto , T. H. Hsieh , T. Kaneko , H. Matsufuru , J. Noaki , T. Onogi , N. Yamada

We discuss the topological phenomena in the QCD-like theories with variable number of fundamental $N_f$ or adjoint $N_a$ fermions, focusing on the temperatures at or above the critical value $T_c$ of chiral symmetry restoration. Nonzero…

High Energy Physics - Phenomenology · Physics 2012-08-10 Edward Shuryak , Tin Sulejmanpasic

Holographic models in the T=0 universality class of QCD in the limit of large number N_c of colors and N_f massless fermion flavors, but constant ratio x_f=N_f/N_c, are analyzed at finite temperature. The models contain a 5-dimensional…

High Energy Physics - Phenomenology · Physics 2015-06-11 T. Alho , M. Jarvinen , K. Kajantie , E. Kiritsis , K. Tuominen

The $U(1)_A$ symmetry of the massless QCD Lagrangian is explicitly broken in the quantised theory by the anomaly. It may be effectively restored at some finite temperature, which would have important consequences for the order of the chiral…

High Energy Physics - Lattice · Physics 2026-01-30 Ryan Bignell , Gert Aarts , Chris Allton , Benjamin Jäger , Seyong Kim , Jon-Ivar Skullerud , Antonio Smecca

We study the anomalous breaking of U_A(1) symmetry just above the QCD phase transition for zero and two flavors of quarks, using a staggered fermion, lattice discretization. The properties of the QCD phase transition are expected to depend…

High Energy Physics - Lattice · Physics 2009-10-31 Shailesh Chandrasekharan , Dong Chen , Norman Christ , Weonjong Lee , Robert Mawhinney , Pavlos Vranas

The chiral phase transition of the quark sector of QCD is investigated within the Hamiltonian approach in Coulomb gauge. Finite temperatures $T$ are introduced by compactifying one spatial dimension, which makes all thermodynamical…

High Energy Physics - Phenomenology · Physics 2018-10-19 Ehsan Ebadati , Hugo Reinhardt , Peter Vastag