Chiral perturbation theory in aθvacuum

Abstract

We consider chiral perturbation theory with a nonzero θ term. Because of the CP violating term, the vacuum of chiral fields is shifted to a nontrivial element on the SU (N f ) group manifold. The CP violation also provides mixing of different CP eigenstates, between scalar and pseudoscalar, or vector and axialvector operators. We investigate upto O(θ 2 ) effects on the mesonic two-point correlators of chiral perturbation theory to the one-loop order. We also address the effects of fixing topology, by using saddle-point integration in the Fourier transform with respect to θ.

Lattice Flavour Physics with an eye to Super-B

“…Some very recent calculations also include the contribution of the dynamical charm quark [3,4,5]. Thanks to the algorithm and action improvements, simulations at light quark masses in the Chiral Perturbation Theory (ChPT) regime have become feasible and, very recently, first simulations at the physical point have been performed [6,7]. A clear indication of the level of accuracy achieved at present in Flavor Lattice QCD calculations is given by the color code introduced by the Flavor Lattice Averaging Group (FLAG) [8].…”

Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD

“…Other recent progress in calculating excited-state energies in lattice QCD can be found in Refs. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Lattice measurement of αs with a realistic charm quark

“…It means including more and more quark species in the sea, u/d quarks (N f = 2), then the strange (N f = 2 + 1) and even the charm (N f = 2 + 1 + 1) since a couple of years. Pion masses ∼ 250 MeV are now common and several collaborations are even able to simulate a real pion, either in a small volume (PACS-CS Collaboration) [5] or using a quark regularisation with a rather aggressive cut-off of the UV regime (BMW Collaboration) [6]. Discretisation errors are kept under control by considering lattice spacings a smaller than 0.1 fm and lattice extensions L are such that Lm π 3.5 to get rid of finite size effects.…”