SUSY

QCD simulations with light dynamical quarks

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qq+q Collaboration

The low energy dynamics in the pseudo-Goldstone boson sector of QCD is constrained by the non-linear realization of spontaneously broken chiral symmetry. In an expansion in powers of momenta and light quark masses a few low energy constants appear which parameterize the strength of interactions in the low energy chiral Lagrangian (see the basic papers by S. Weiberg, J. Gasser and H. Leutwyler). These Gasser-Leutwyler constants are free parameters which can be constrained by analyzing experimental data. In the framework of lattice regularization they can be determined from first principles by numerical simulations.

Chiral Perturbation Theory
In the qq+q collaboration we performed numerical simulations with two (qq) or three (qq+q) light dynamical ("unquenched") quarks and confront the results with Chiral Perturbation Theory (ChPT).

Algorithm development
The numerical simulations have been performed by using the two-step multi-boson (TSMB) algorithm which is well suited for light fermions.

Twisted mass quarks

Twisted mass quarks (S. Aoki, Phys.Rev. D30 (1984) 2653) provide a useful lattice regularization of QCD (hep-lat/0101001). Recently it has been shown that this formulation has "automatic" O(a) improvement (hep-lat/0306014) and can naturally be extended to deal with non-degenerate-mass quark doublets (hep-lat/0311008). In a collaboration with NIC-Zeuthen and University of M\"unster we recently started a detailed exploration of numerical simulations in the twisted mass lattice formulation.

Publication list

F. Farchioni, C. Gebert, I. Montvay, L. Scorzato,
Numerical simulation tests with light dynamical quarks,
Eur. Phys. J. C26:237-251, (2002);  hep-lat/0206008

F. Farchioni, C. Gebert, I. Montvay, L. Scorzato,
Lattice QCD with light dynamical quarks,
Nucl. Phys. Proc. Suppl. 119:344-349, (2003);  hep-lat/0209038

F. Farchioni, C. Gebert, I. Montvay, L. Scorzato,
On the price of light quarks,
hep-lat/0209142

I. Montvay,
Numerical simulation with light Wilson quarks,
hep-lat/0301013

F. Farchioni, C. Gebert, I. Montvay, E. Scholz, L. Scorzato,
Partially quenched chiral perturbation theory and numerical simulations,
Phys. Lett. B561:102-110, (2003);  hep-lat/0302011

F. Farchioni, I. Montvay, E. Scholz, L. Scorzato,
Quark mass dependence of masses and decay constants of the pseudo-Goldstone bosons in QCD,
Eur. Phys. J. C31:227-238, (2003);  hep-lat/0307002

F. Farchioni, C. Gebert, I. Montvay, E. Scholz, L. Scorzato,
Quark mass dependence of pseudoscalar masses and coupling constants,
Nucl. Phys. Proc. Suppl. 129:179-181, (2004);  hep-lat/0309094

F. Farchioni, I. Montvay, E. Scholz,
Quark mass dependence of pseudoscalar masses and decay constants on a lattice,
Eur. Phys. J. C37:197-204, (2004);  hep-lat/0403014

F. Farchioni, I. Montvay, E. Scholz,
Unquenched simulations with Nf=2 light quark flavours,
Nucl. Phys. Proc. Suppl. 140:249-251, (2005);  hep-lat/0409004

F. Farchioni, R. Frezzotti, K. Jansen, I. Montvay, G.C. Rossi, E. Scholz, A. Shindler, N. Ukita, C. Urbach, I. Wetzorke,
Twisted mass quarks and the phase structure of lattice QCD,
Eur. Phys. J. C39:421-433, (2005);  hep-lat/0406039

F. Farchioni, C. Urbach, R. Frezzotti, K. Jansen, I. Montvay, G.C. Rossi, E. Scholz, A. Shindler, N. Ukita, I. Wetzorke,
Exploring the phase structure of lattice QCD with twisted mass quarks,
Nucl. Phys. Proc. Suppl. 140:240-245, (2005);  hep-lat/0409098

F. Farchioni, K. Jansen, I. Montvay, E. Scholz, L. Scorzato, A. Shindler, N. Ukita, C. Urbach, I. Wetzorke,
The phase structure of lattice QCD with Wilson quarks and renormalization group improved gluons,
Eur. Phys. J. C42:73-87, (2005);  hep-lat/0410031

F. Farchioni, K. Jansen, I. Montvay, E.E. Scholz, L. Scorzato, A. Shindler, N. Ukita, C. Urbach, U. Wenger, I. Wetzorke,
Lattice spacing dependence of the first order phase transition for dynamical twisted mass fermions,
Phys. Lett. B624:324-333, (2005);  hep-lat/0506025

F. Farchioni, K. Jansen, C. McNeile, C. Michael, I. Montvay, K. Nagai, M. Papinutto, J. Pickavance, E. Scholz, L. Scorzato, A. Shindler, N. Ukita, C. Urbach, U. Wenger, I. Wetzorke,
Twisted mass fermions: neutral pion masses from disconnected contributions,
hep-lat/0509036

F. Farchioni, P. Hofmann, K. Jansen, I. Montvay, G. Munster, M. Papinutto, E. E. Scholz, L. Scorzato, A. Shindler, N. Ukita, C. Urbach, U. Wenger, I. Wetzorke,
Dynamical twisted mass fermions,
hep-lat/0509131

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Last change on November 9, 2005