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We provide numerical evidence that the thermal QCD crossover turns into a first order transition in the presence of large enough magnetic background fields. The critical endpoint is found to be located between $eB = 4$ GeV$^2$ (where the…

High Energy Physics - Lattice · Physics 2022-03-14 Massimo D'Elia , Lorenzo Maio , Francesco Sanfilippo , Alfredo Stanzione

We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point $(T, m_q = 0)$ in the temperature vs. quark-mass plane indicates that a sharp real-time…

High Energy Physics - Lattice · Physics 2014-10-23 Bastian B. Brandt , Anthony Francis , Harvey B. Meyer , Daniel Robaina

Above the QCD chiral crossover temperature, the low-lying eigenmodes of the Dirac operator are localised, while moving up in the spectrum states become extended. This localisation/delocalisation transition has been shown to be a genuine…

High Energy Physics - Lattice · Physics 2014-10-24 Matteo Giordano , Tamas G. Kovacs , Ferenc Pittler

We present results of an ongoing study of the nature of the high temperature crossover in QCD with two light fermion flavors. These results are obtained with the conventional staggered fermion action at the smallest lattice spacing to…

We investigate the connection between localization of low-lying Dirac modes and Polyakov-loop ordering in the lattice $\mathrm{SU}(2)$ Higgs model at finite temperature, probed with the staggered Dirac operator. After mapping out the phase…

High Energy Physics - Lattice · Physics 2024-03-13 György Baranka , Matteo Giordano

At low temperature the low-lying QCD Dirac spectrum obeys random matrix statistics. Recently we found that above $T_{c}$ the lowest part of the spectrum consists of localized modes that obey Poisson statistics. An interesting implication of…

High Energy Physics - Lattice · Physics 2014-11-03 Matteo Giordano , Sandor D. Katz , Tamas G. Kovacs , Ferenc Pittler

The QCD phase transition is studied on $16^3$ and $32^3 \times 4$ lattices both with and without quark loops. We introduce a new zero-flavor or quenched species of quark $\zeta$ and study the resulting chiral condensate, $\azbz$ as a…

High Energy Physics - Lattice · Physics 2009-10-28 Shailesh Chandrasekharan , Norman Christ

We report on the first lattice calculation of the QCD phase transition using chiral fermions at physical values of the quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm$)^3$ and (11 fm$)^3$ and…

We analyze the pseudo-critical behavior of three-flavor QCD using highly improved staggered quarks (HISQ) on lattices with temporal extent $N_\tau =8$ and for quark masses corresponding to a pseudoscalar Goldstone mass in the range $80 ~…

High Energy Physics - Lattice · Physics 2022-04-08 Lorenzo Dini , Prasad Hegde , Frithjof Karsch , Anirban Lahiri , Christian Schmidt , Sipaz Sharma

We investigate the effects of low-lying fermion eigenmodes on the QCD partition function in the $\epsilon$-regime. The fermion determinant is approximated by a truncated product of low-lying eigenvalues of the overlap-Dirac operator. With…

High Energy Physics - Lattice · Physics 2009-11-11 Kenji Ogawa , Shoji Hashimoto

This paper is devoted to the temperature dependence of the resistivity in Si- MOS samples over the wide range of densities in the ``metallic phase'' (n>n_c) but not too close to the critical density n_c. Three domains of different behavior…

Strongly Correlated Electrons · Physics 2007-05-23 B. L. Altshuler , G. W. Martin , D. L. Maslov , V. M. Pudalov , A. Prinz , G. Brunthaler , G. Bauer

We investigate the QCD Dirac operator with gauge configurations given by a liquid of instantons in the region of temperatures about the chiral phase transition. Both the quenched and unquenched cases are examined in detail. We present…

High Energy Physics - Phenomenology · Physics 2008-11-26 Antonio M. Garcia-Garcia , James C. Osborn

We present results from a calculation of the transition temperature in QCD with two light and one heavier (strange) quark mass on lattices with temporal extent N_t =4 and 6. Calculations with improved staggered fermions have been performed…

High Energy Physics - Phenomenology · Physics 2009-11-13 Frithjof Karsch

We present our most recent investigations on the QCD cross-over transition temperatures with 2+1 staggered flavours and one-link stout improvement [JHEP 1009:073, 2010]. We extend our previous two studies [Phys. Lett. B643 (2006) 46, JHEP…

High Energy Physics - Lattice · Physics 2011-09-16 Szabolcs Borsanyi , Zoltan Fodor , Christian Hoelbling , Sandor D. Katz , Stefan Krieg , Claudia Ratti , Kalman K. Szabo

We explore the properties of low lying eigenmodes of fermions in the quenched approximation of lattice QCD. The fermion action is a recently proposed overlap action and has exact chiral symmetry. We find that chiral zero-eigenvalue modes…

High Energy Physics - Lattice · Physics 2009-10-31 Thomas DeGrand , Anna Hasenfratz

Low-lying Dirac modes become localized at the finite-temperature transition in QCD and other gauge theories, indicating a strong connection between localization and deconfinement. This phenomenon can be understood through the "sea/islands"…

High Energy Physics - Lattice · Physics 2025-01-24 György Baranka , Matteo Giordano

We suggest that the lattice Dirac spectra in QCD at finite temperature may be understood using a gaussian unitary ensemble for Wilson fermions, and a chiral gaussian unitary ensemble for Kogut-Susskind fermions. For Kogut-Susskind fermions,…

High Energy Physics - Phenomenology · Physics 2009-10-28 Maciej A. Nowak , Gábor Papp , Ismail Zahed

The QCD transition is studied on lattices up to $N_t=16$. The chiral condensate is presented as a function of the temperature, and the corresponding transition temperature is extracted. The equation of state is determined on lattices with…

We study the axial U(1)A symmetry of Nf = 2 QCD at finite temperature using the Dirac eigenvalue spectrum. The gauge configurations are generated employing the Mobius domain-wall fermion action on 16^3x8 and 32^3x8 lattices. The physical…

High Energy Physics - Lattice · Physics 2014-12-24 Akio Tomiya , Guido Cossu , Hidenori Fukaya , Shoji Hashimoto , Junichi Noaki

Based on the $t-t'-U-V$ model with proper chosen parameters for describing the cuprate superconductors, it is found that near the optimal doping at low temperature ($T$), only the pure d-wave superconductivity ($d$SC) prevails and the…

Superconductivity · Physics 2009-11-10 Hong-Yi Chen , C. S. Ting