arXiv subjects

Luigi Scorzato

Publications and source records attributed to Luigi Scorzato.

25 records · Page 2Linked to original sources

arXiv2007

High loop renormalization constants by NSPT: a status report

We present an update on Numerical Stochastic Perturbation Theory projects for Lattice QCD, which are by now run on apeNEXT. As a first issue, we discuss a strategy to tackle finite size effects which can be quite sizeable in the computation of logarithmically divergent renormalization constants. Our first high loop determination of quark bilinears for Wilson fermions was limited to finite constants and finite ratios. A precise determination of Z_P and Z_S (and hence of Z_m) now becomes possible. We also give an account of computations for actions different from the standard regularization we have taken into account so far (Wilson gauge action and Wilson fermions). In particular, we present the status of computations for the Lattice QCD regularization defined by tree level Symanzik improved gauge action and Wilson fermions, which became quite popular in recent times. We also take the chance to discuss the related topic of the computation of the gluon and ghost propagators (which we undertook in collaboration with another group). This is relevant in order to better understand non-perturbative computations of propagators aiming at qualitative/quantitative understanding of confinement.

hep-lat↗

arXiv2006

Renormalization constants for Lattice QCD: new results from Numerical Stochastic Perturbation Theory

By making use of Numerical Stochastic Perturbation Theory (NSPT) we can compute renormalization constants for Lattice QCD to high orders, e.g. three or four loops for quark bilinears. We report on the status of our computations, which provide several results for Wilson quarks and in particular (values and/or ratios of) Z_V, Z_A, Z_S, Z_P. Results are given for various number of flavors (n_f = 0, 2, 3, 4). While we recall the care which is due for the computation of quantities for which an anomalous dimension is in place, we point out that our computational framework is well suited to a variety of other calculations and we briefly discuss the application of NSPT to other regularizations (in particular the Clover action).

hep-lat↗

arXiv2004

The Nf=2 residual mass in Perturbative Lattice-HQET for an improved determination of the (MS bar) b-quark mass

We determine to order alpha^3 the so-called residual mass in the lattice regularisation of the Heavy Quark Effective Theory for Nf=2. Our (gauge-invariant) strategy makes use of Numerical Stochastic Perturbation Theory to compute the static interquark potential where the above mentioned mass term appears as an additive contribution. We discuss how the new coefficient we compute in the expansion of the residual mass can improve the determination of the (MS bar) mass of the b-quark from lattice simulations of the Heavy Quark Effective Theory.

hep-lat↗

arXiv2004

Pion mass splitting and phase structure in Twisted Mass QCD

In the framework of Wilson Chiral Perturbation Theory, we study the effect induced by a twisted Wilson term, as it appears in Twisted Mass QCD (with 2 degenerate quarks). In particular we consider the vacuum orientation and the pion masses. The computations are done to NLO both in the mass and in the lattice spacing (i.e. to O(a^2)). There are no restrictions on the relative size of lattice artifacts with respect to the physical mass, thus allowing, in principle, to bridge between the physical regime and the unphysical one, where lattice artifacts tend to dominate. The inclusion of O(a^2) lattice artifacts can account for the splitting of degeneracy of the three pion masses. Moreover O(a^2) terms are necessary to model non trivial behaviors of the vacuum orientation such as possible Aoki phases. It turns out that these last two phenomena are determined by the same constant.

hep-lat↗

arXiv2003

Lattice simulations of 2-colour QCD with Wilson fermions

We report on the status of our simulations of two-colour QCD with two flavours of Wilson quarks, at nonzero chemical potential and diquark source. Preliminary results are presented for the static quark potential, gluon propagator, and meson and diquark spectrum.

hep-lat↗

arXiv2001

Diquark condensation in dense SU(2) matter

We report on a lattice study of two-color QCD with adjoint staggered fermions at high density. We find that the model has no early onset and we report on results for diquark condensation, from simulations with and without a diquark source term.

hep-lat↗

arXiv2000

Numerical Study of dense adjoint 2-color matter

We study the global symmetries of SU(2) gauge theory with N flavors of staggered fermions in the presence of a chemical potential. We motivate the special interest of the case N=1 (staggered) with fermions in the adjoint representation of the gauge group. We present results from numerical simulations with both hybrid Monte Carlo and the Two-Step Multi-Bosonic algorithm.

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