Conveners
Chiral Symmetry
- Robert Mawhinney
Chiral Symmetry
- Andrei Alexandru
Mr
Venkit Ayyar
(Duke University)
16/07/2015, 08:30
Chiral Symmetry
Talk
We 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....
Prof.
Shinsuke Nishigaki
(Shimane University)
16/07/2015, 08:50
Chiral Symmetry
Talk
Based 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...
Dr
Savvas Zafeiropoulos
(Goethe University Frankfurt)
16/07/2015, 09:10
Chiral Symmetry
Talk
We 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...
Prof.
Jacobus Verbaarschot
(Stony Brook University)
16/07/2015, 09:30
Chiral Symmetry
Talk
The 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...
Dr
Andrei Alexandru
(The George Washington University)
16/07/2015, 09:50
Chiral Symmetry
Talk
In 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...
Mr
David Murphy
(Columbia University)
16/07/2015, 10:40
Chiral Symmetry
Talk
We 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...
Robert Mawhinney
(Columbia University)
16/07/2015, 11:00
Chiral Symmetry
Talk
We 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...
Dr
Markus Pak
(University of Graz)
16/07/2015, 11:20
Chiral Symmetry
Talk
Recently, 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...
Dr
Konstantin Ottnad
(University of Bonn)
16/07/2015, 11:40
Chiral Symmetry
Talk
We 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...
