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We investigate the phase structure of lattice QCD for general number of flavors $N_F$. Based on numerical data combined with the results of the perturbation theory we propose the following picture: When $N_F \ge 17$, there is only one IR…

High Energy Physics - Lattice · Physics 2008-11-26 Y. Iwasaki , K. Kanaya , S. Kaya , S. Sakai , T. Yoshié

When the number of massless fermions exceeds a critical value $N_f^*$, QCD enters the conformal window and becomes chirally symmetric already in the vacuum. Determining $N_f^*$ from lattice simulations is challenging, since calculations are…

High Energy Physics - Lattice · Physics 2026-03-23 Jan Philipp Klinger , Reinhold Kaiser , Owe Philipsen , Jonas Schaible

We study the axial U(1) symmetry at finite temperature in two-flavor lattice QCD. Employing the Mobius domain-wall fermions, we generate gauge configurations slightly above the critical temperature Tc with different lattice sizes L = 2-4…

High Energy Physics - Lattice · Physics 2017-10-30 A. Tomiya , G. Cossu , S. Aoki , H. Fukaya , S. Hashimoto , T. Kaneko , J. Noaki

SU(2) with Nf=8 is believed to have an infrared conformal fixed point. We use the spectral density method to evaluate the coupling constant dependence of the mass anomalous dimension for massless HEX smeared, clover improved Wilson fermions…

High Energy Physics - Lattice · Physics 2015-11-12 Joni M. Suorsa , Viljami Leino , Jarno Rantaharju , Teemu Rantalaiho , Kari Rummukainen , Kimmo Tuominen , David J. Weir

Using lattice simulations, we study the extent of the conformal window for an $\text{SU}(3)$ gauge theory with $N_f$ Dirac fermions in the fundamental representation. We present evidence that the infrared behavior is conformal for $12 \leq…

High Energy Physics - Phenomenology · Physics 2009-12-15 Thomas Appelquist , George T. Fleming , Ethan T. Neil

We present our investigations of SU($N$) adjoint QCD in two dimensions with one Majorana fermion on the lattice. We determine the relevant parameter range for the simulations with Wilson fermions and present results for Polyakov loop,…

High Energy Physics - Lattice · Physics 2024-04-08 Georg Bergner , Stefano Piemonte , Mithat Ünsal

In this joint contribution we announce the formation of the "OPEN LATtice initiative", https://openlat1.gitlab.io, to study Stabilised Wilson Fermions (SWF). They are a new avenue for QCD calculations with Wilson-type fermions and we report…

The anomalous dimension $\gamma_m =1$ in the infrared region near conformal edge in the broken phase of the large $N_f$ QCD has been shown by the ladder Schwinger-Dyson equation and also by the lattice simulation for $N_f=8$ for $ N_c=3$.…

High Energy Physics - Phenomenology · Physics 2023-10-06 Koichi Yamawaki

We define a scale-dependent effective mass anomalous dimension from the scaling of the mode number of the massless Dirac operator, which connects the perturbative $\gamma_m$ of an asymptotically-free system to the universal…

High Energy Physics - Lattice · Physics 2022-09-21 Anqi Cheng , Anna Hasenfratz , Gregory Petropoulos , David Schaich

Anisotropic lattice spacings are mandatory to reach the high temperatures where chiral symmetry is restored in the strong coupling limit of lattice QCD. Here, we propose a simple criterion for the nonperturbative renormalisation of the…

High Energy Physics - Lattice · Physics 2018-03-09 Philippe de Forcrand , Wolfgang Unger , Helvio Vairinhos

We study the $U(1)_A$ anomaly in the high-temperature phase of $N_f=2+1$ lattice QCD with chiral fermions. Gauge ensembles are generated with M\"obius domain-wall (MDW) fermions, and in the measurements the determinant is reweighted to that…

The Vafa-Witten arguments on the realization of parity and flavour symmetries in the QCD vacuum do not apply to two lattice regularizations of QCD which are able to reproduce the chiral anomaly: Wilson fermions and Ginsparg-Wilson fermions.…

High Energy Physics - Lattice · Physics 2010-11-04 V. Azcoiti , G. Di Carlo , E. Follana , A. Vaquero

The flavour singlet axial Ward identity with Osterwalder-Seiler twisted mass Wilson fermion action is studied on a finite lattice, with finite fermion mass and the Wilson parameter r up to 1. Approach to the infinite volume chiral limit and…

High Energy Physics - Lattice · Physics 2010-02-26 Asit K. De , A. Harindranath , Santanu Mondal

One major systematic uncertainty of lattice QCD results is due to the continuum extrapolation. For an asymptotically free theory like QCD one finds corrections of the form $a^{n_\mathrm{min}}[2b_0\bar{g}^2(1/a)]^{\hat{\Gamma}_i}$ with…

High Energy Physics - Lattice · Physics 2022-12-20 Nikolai Husung

We report extended simulation results and their new analysis in two important gauge theories with twelve fermion flavors in the fundamental SU(3) color representation and two fermions in the sextet representation. We probe the $N_f=12$…

High Energy Physics - Lattice · Physics 2012-05-10 Zoltan Fodor , Kieran Holland , Julius Kuti , Daniel Nogradi , Chris Schroeder , Chik Him Wong

The OpenLat initiative presents its results of lattice QCD simulations using Stabilized Wilson Fermions (SWF) using 2+1 quark flavors. Focusing on the $\mathrm{SU}(3)$ flavor symmetric point $m_\pi=m_K=412$ MeV, four different lattice…

We construct unitary, stable, and interacting conformal boundary conditions for a free massless scalar in four dimensions by coupling it to edge modes living on a boundary. The boundary theories we consider are bosonic and fermionic QED$_3$…

High Energy Physics - Theory · Physics 2024-04-03 Lorenzo Di Pietro , Edoardo Lauria , Pierluigi Niro

Infrared fixed points of gauge theories provide intriguing targets for the modern conformal bootstrap program. In this work we provide some preliminary evidence that a family of gauged fermionic CFTs saturate bootstrap bounds and can…

High Energy Physics - Theory · Physics 2021-03-29 Zhijin Li , David Poland

We study the evolution of the coupling in SU(2) gauge field theory with $N_f=4$, 6 and 10 fundamental fermion flavours on the lattice. These values are chosen close to the expected edges of the conformal window, where the theory possesses…

High Energy Physics - Lattice · Physics 2015-03-19 Tuomas Karavirta , Jarno Rantaharju , Kari Rummukainen , Kimmo Tuominen

We study the conformal window of asymptotically free gauge theories containing $N_f$ flavors of fermion matter transforming to the vector and two-index representations of $SO(N),~SU(N)$ and $Sp(2N)$ gauge groups. For $SO(N)$ we also…

High Energy Physics - Phenomenology · Physics 2021-04-14 Jong-Wan Lee