Conveners
Chiral Symmetry
- Robert Mawhinney
Chiral Symmetry
- Andrei Alexandru
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Mr Venkit Ayyar (Duke University)16/07/2015, 08:30Chiral SymmetryTalkWe study two flavors of massless staggered fermions interacting via an on-site four- fermion interaction and argue that the model contains an exotic quantum critical point separating the perturbative massless phase from a massive fermion phase at strong cou- plings where the fermion bilinear condensate remains zero. We believe that no spontaneous symmetry breaking occurs at the transition....Go to contribution page
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Prof. Shinsuke Nishigaki (Shimane University)16/07/2015, 08:50Chiral SymmetryTalkBased on the exact relationship to random matrix theory, we present alternative methods of evaluating the probability distribution of the k-th smallest Dirac eigenvalue in the epsilon regime of QCD and related gauge theories. By employing (1) the Nystrom-type evaluation of Fredholm determinants and Pfaffians and/or (2) the interrelationship between tau functions for random matrix ensembles at...Go to contribution page
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Dr Savvas Zafeiropoulos (Goethe University Frankfurt)16/07/2015, 09:10Chiral SymmetryTalkWe present the comparison of the analytical microscopic spectral density for lattice QCD with $N_f=2$ twisted mass fermions with the one obtained on the lattice utilizing configurations produced by the ETM collaboration. We extract estimates for the chiral condensate as well as the low-energy constant $W_8$ of Wilson $\chi$-PT by employing spectral information of the Wilson Dirac operator...Go to contribution page
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Prof. Jacobus Verbaarschot (Stony Brook University)16/07/2015, 09:30Chiral SymmetryTalkThe behavior of quenched Dirac spectra of two-dimensional lattice QCD is consistent with spontaneous chiral symmetry breaking which is forbidden according to the Coleman-Mermin-Wagner theorem. One possible resolution of this paradox is that because of the bosonic determinant that enters in the partially quenched partition function the conditions of this theorem are violated allowing...Go to contribution page
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Dr Andrei Alexandru (The George Washington University)16/07/2015, 09:50Chiral SymmetryTalkIn the presence of a constant electric field the vacuum becomes unstable due to Schwinger pair creation. One way to avoid this instability is to use Dirichlet boundary conditions. In this case the chiral condensate vanishes on the walls and it is important to know how quickly it gets restored to its bulk value. A sigma-model calculation predicts that the region where the condensate...Go to contribution page
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Mr David Murphy (Columbia University)16/07/2015, 10:40Chiral SymmetryTalkWe have performed global fits of $f_\pi$ and $m_\pi$, from a variety of RBC-UKQCD domain wall fermion ensembles, to $SU(2)$ partially quenched chiral perturbation theory at NNLO. We report values for 9 NLO and 8 linearly independent combinations of NNLO partially quenched low energy constants, which we compare to other lattice and phenomenological determinations. We discuss the convergence of...Go to contribution page
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Robert Mawhinney (Columbia University)16/07/2015, 11:00Chiral SymmetryTalkWe have performed global fits of pseudoscalar masses and decay constants, from a variety of RBC-UKQCD domain wall fermion ensembles, to $SU(3)$ partially quenched chiral perturbation theory at NNLO. We report values for 9 NLO and 10 linearly independent combinations of NNLO partially quenched low energy constants, which we compare to other lattice and phenomenological determinations. We...Go to contribution page
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Dr Markus Pak (University of Graz)16/07/2015, 11:20Chiral SymmetryTalkRecently, a new $SU(4)$ symmetry has been established, which appears after removing the quasi-zero modes from the Overlap Dirac operator. Namely, the $\rho, \rho', \omega, \omega', a_1, b_1$ and possibly $f_1$ $J=1$ mesons become mass degenerate after the quasi-zero mode removal. The $SU(4)$ symmetry contains $SU(2)_L \times SU(2)_R \times U(1)_A$ as a subgroup and predicts, among other...Go to contribution page
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Dr Konstantin Ottnad (University of Bonn)16/07/2015, 11:40Chiral SymmetryTalkWe employ lattice techniques to compute both sides of the Witten-Veneziano formula. For the one side we perform dedicated quenched simulations and use the spectral projector method to determine the topological susceptibility in pure Yang-Mills theory. The other side we determine in lattice QCD with $N_f=2+1+1$ dynamical Wilson twisted mass fermions including for the first time also the...Go to contribution page