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We discuss some properties of zero and near-zero modes of the Dirac operator, as observed in a recent simulation of 2-flavor QCD. The quarks have been implemented with the so-called Chirally Improved Dirac operator, which obeys the…

High Energy Physics - Lattice · Physics 2007-05-23 C. B. Lang , Pushan Majumdar , Wolfgang Ortner

Superconformal Ward identities are derived for the the four point functions of chiral primary BPS operators for $\N=2,4$ superconformal symmetry in four dimensions. Manipulations of arbitrary tensorial fields are simplified by introducing a…

High Energy Physics - Theory · Physics 2010-04-05 M. Nirschl , H. Osborn

We present results for the non-perturbative determination of the improvement and renormalization factors of the isovector axial current for lattice QCD with two flavors of dynamical Wilson quarks. The improvement and normalization…

High Energy Physics - Lattice · Physics 2007-05-23 Roland Hoffmann , Michele Della Morte , Francesco Knechtli , Rainer Sommer , Ulli Wolff

A generalization of the Fermion-Loop scheme is introduced to account for external, non-conserved, currents. Complete Dyson re-summed transitions are introduced, including the contributions from the Higgs-Kibble ghosts in the 't…

High Energy Physics - Phenomenology · Physics 2009-10-31 G. Passarino

Real-time anomalous fermion number violation is investigated for massless chiral fermions in spherically symmetric SU(2) Yang-Mills gauge field backgrounds which can be weakly dissipative or even nondissipative. Restricting consideration to…

High Energy Physics - Theory · Physics 2009-11-07 F. R. Klinkhamer , Y. J. Lee

In a recent paper we introduced the chirality-flow formalism, a method for simple and transparent calculations of Feynman diagrams based on the left- and right-chiral $\mathrm{sl}(2,\mathbb{C})$ nature of spacetime. While our previous work…

High Energy Physics - Phenomenology · Physics 2023-03-09 Joakim Alnefjord , Andrew Lifson , Christian Reuschle , Malin Sjodahl

We define chiral fermions in the presence of non-trivial gravitational and gauge background fields in the framework of locally covariant field theory. This allows to straightforwardly compute the chiral anomalies on non-compact Lorentzian…

High Energy Physics - Theory · Physics 2015-01-09 Jochen Zahn

We non-perturbatively determine the renormalization factor of the axial vector current in lattice QCD with $N_f=3$ flavors of Wilson-clover fermions and the tree-level Symanzik-improved gauge action. The (by now standard) renormalization…

High Energy Physics - Lattice · Physics 2016-06-29 John Bulava , Michele Della Morte , Jochen Heitger , Christian Wittemeier

We describe an adaptive multigrid algorithm for solving inverses of the domain-wall fermion operator. Our multigrid algorithm uses an adaptive projection of near-null vectors of the domain-wall operator onto coarser four-dimensional…

High Energy Physics - Lattice · Physics 2012-05-15 Saul D. Cohen , R. C. Brower , M. A. Clark , J. C. Osborn

The reweighting method is applied to improve the chiral property of domain-wall fermions. One way to achieve this is to enlarge $L_s$, the size of fifth dimension, which controls the size of the induced chiral symmetry breaking. While this…

High Energy Physics - Lattice · Physics 2010-03-11 Tomomi Ishikawa , Yasumichi Aoki , Taku Izubuchi

Many observables of interest in lattice QCD are extracted from correlation functions involving the vector current. If Wilson fermions are used, it is therefore of practical importance that, besides the action, the current be O($a$) improved…

High Energy Physics - Lattice · Physics 2015-12-16 Tim Harris , Harvey B. Meyer

We describe a way to optimize the chiral behavior of Wilson-type lattice fermion actions by studying the low energy real eigenmodes of the Dirac operator. We find a candidate action, the clover action with fat links with a tuned clover…

High Energy Physics - Lattice · Physics 2007-05-23 Thomas DeGrand , Anna Hasenfratz , Tamás G. Kovács

We extend work by Callan and Harvey and show how the phase of the chiral fermion determinant in four dimensions is reproduced by zeromodes bound to a domain wall in five dimensions. The analysis could shed light on the applicability of…

High Energy Physics - Theory · Physics 2019-08-15 David B. Kaplan , Martin Schmaltz

We study the frequency dependence of all the chiral vortical and magnetic conductivities for a relativistic gas of free chiral fermions and for a strongly coupled conformal field theory with holographic dual in four dimensions. Both systems…

High Energy Physics - Phenomenology · Physics 2014-10-01 Karl Landsteiner , Eugenio Megias , Francisco Peña Benítez

We show that with suitable choices of parametrization, gauge fixing and cutoff, the anomalous variation of the effective action under global rescalings of the background metric is identical to the derivative with respect to the cutoff, i.e.…

High Energy Physics - Theory · Physics 2017-03-08 Roberto Percacci , Gian Paolo Vacca

The exact solution of the Dirac equation for fermions coupled to an external periodic chiral condensate (chiral spiral) is used to obtain the exact formula for the Wigner function (up to the quantum loop corrections). We find that the…

High Energy Physics - Phenomenology · Physics 2025-07-29 Samapan Bhadury , Wojciech Florkowski , Sudip Kumar Kar , Valeriya Mykhaylova

We derive the formal Ward identities relating pseudoscalar susceptibilities and quark condensates in three-flavor QCD, including consistently the $\eta$-$\eta'$ sector and the $U_A(1)$ anomaly. These identities are verified in the…

High Energy Physics - Phenomenology · Physics 2017-10-24 A. Gomez Nicola , J. Ruiz de Elvira

Domain wall fermions provide a complimentary alternative to traditional lattice fermion approaches. By introducing an extra dimension, the amount of chiral symmetry present in the lattice theory can be controlled in a linear way. This…

High Energy Physics - Lattice · Physics 2009-10-31 Pavlos Vranas

We propose a method to improve lattice operators composed of Wilson fermions which allows the removal of all corrections of $O(a)$, including those proportional to the quark mass. It requires off-shell improvement of quark fields and…

High Energy Physics - Lattice · Physics 2009-10-09 G. Martinelli , G. C. Rossi , C. T. Sachrajda , S. Sharpe , M. Talevi , M. Testa

Chiral perturbation theory for eigenvalue distributions, and equivalently random matrix theory, has recently been extended to include lattice effects for Wilson fermions. We test the predictions by comparison to eigenvalue distributions of…

High Energy Physics - Lattice · Physics 2013-01-15 Poul H. Damgaard , Urs M. Heller , Kim Splittorff