Searcharxiv⌕ Search

arXiv subjects

Mauro Papinutto

Publications and source records attributed to Mauro Papinutto.

30 records · Page 2Linked to original sources
arXiv2014

Non-perturbative renormalization and running of Delta F=2 four-fermion operators in the SF scheme

We present preliminary results of a non-perturbative study of the scale-dependent renormalization constants of a complete basis of Delta F=2 parity-odd four-fermion operators that enter the computation of hadronic B-parameters within the Standard Model (SM) and beyond. We consider non-perturbatively O(a) improved Wilson fermions and our gauge configurations contain two flavors of massless sea quarks. The mixing pattern of these operators is the same as for a regularization that preserves chiral symmetry, in particular there is a "physical" mixing between some of the operators. The renormalization group running matrix is computed in the continuum limit for a family of Schrodinger Functional (SF) schemes through finite volume recursive techniques. We compute non-perturbatively the relation between the renormalization group invariant operators and their counterparts renormalized in the SF at a low energy scale, together with the non-perturbative matching matrix between the lattice regularized theory and the various SF schemes.

hep-lat↗
arXiv2010

Low lying baryon spectrum with $N_f = 2+1+1$ dynamical twisted quarks

We present first results on the octet and decuplet strange baryon spectrum with $N_f=2+1+1$ twisted mass quarks. We use an Osterwalder Seiler valence strange quark with a mass tuned to the kaon and compare the results with those obtained in the unitary setup. This comparison allows to perform a first study of the lattice artefacts introduced by the mixed action approach. We investigate the effect of the strange and charm quarks in the sea by using two lattice spacings and comparing with preceding $N_f = 2$ twisted mass fermion calculations.

hep-lat↗
arXiv2010

Strange and charmed baryons using N_f=2 twisted mass QCD

We compute the mass spectrum for strange/charmed baryons in the partially quenched approach using N_f=2 twisted mass QCD configurations. We investigate two main issues: the size of lattice artefacts using three values of the lattice spacing (the smallest of which is approximately 0.05 fm) and the dependence of baryon masses on meson (or quark) masses. We thus perform a global fit in order to extrapolate simultaneously to the continuum limit and to the physical point. We estimate the masses of Omega_{sss}, Xi_{dss}, Lambda_{uds}, Omega_{ccc}, Xi_{dcc}, Lambda_{udc}.

hep-lat↗
arXiv2010

Geometrical Properties of Two-Dimensional Interacting Self-Avoiding Walks at the Theta-Point

We perform a Monte Carlo simulation of two-dimensional N-step interacting self-avoiding walks at the theta point, with lengths up to N=3200. We compute the critical exponents, verifying the Coulomb-gas predictions, the theta-point temperature T_theta = 1.4986(11), and several invariant size ratios. Then, we focus on the geometrical features of the walks, computing the instantaneous shape ratios, the average asphericity, and the end-to-end distribution function. For the latter quantity, we verify in detail the theoretical predictions for its small- and large-distance behavior.

cond-mat.soft↗
arXiv2008

Heavy Quark Effective Theory computation of the mass of the bottom quark

We present a fully non-perturbative computation of the mass of the b-quark in the quenched approximation. Our strategy starts from the matching of HQET to QCD in a finite volume and finally relates the quark mass to the spin averaged mass of the Bs meson in HQET. All steps include the terms of order Lambda^2/Mb. Expanding on [1], we discuss the computation and renormalization of correlation functions at order 1/Mb. With the strange quark mass fixed from the Kaon mass and the QCD scale set through r0=0.5 fm, we obtain a renormalization group invariant mass Mb = 6.758(86) GeV or mb(mb)= 4.347(48) GeV in the MS-bar scheme. The uncertainty in the computed Lambda^2/Mb terms contributes little to the total error and Lambda^3/Mb^2 terms are negligible. The strategy is promising for full QCD as well as for other B-physics observables.

hep-ph↗
arXiv2007

Non-perturbative renormalization of static-light four-fermion operators in quenched lattice QCD

We perform a non-perturbative study of the scale-dependent renormalization factors of a multiplicatively renormalizable basis of $Δ{B}=2$ parity-odd four-fermion operators in quenched lattice QCD. Heavy quarks are treated in the static approximation with various lattice discretizations of the static action. Light quarks are described by non-perturbatively ${\rm O}(a)$ improved Wilson-type fermions. The renormalization group running is computed for a family of Schroedinger functional (SF) schemes through finite volume techniques in the continuum limit. We compute non-perturbatively the relation between the renormalization group invariant operators and their counterparts renormalized in the SF at a low energy scale. Furthermore, we provide non-perturbative estimates for the matching between the lattice regularized theory and all the SF schemes considered.

hep-lat↗
arXiv2005

A quenched study of m_b in HQET beyond the leading order

A non perturbative method to compute the mass of the b quark including the 1/m term in HQET has been presented in a companion talk. Following this strategy, we find in the MS bar scheme m_b^{stat}(m_b) = 4.350(64) GeV for the leading term, and m_b^{(1)}(m_b) = -0.049(29) GeV for the next to leading order correction. This method involves several steps, including the simulation of the relativistic theory in a small volume, and of the effective theory in a big volume. Here we present some numerical details of our calculations.

hep-lat↗
arXiv2005

Cutoff effects in maximally twisted LQCD

The Symanzik analysis of correlators in lattice QCD with maximally twisted Wilson fermions reveals that there exist cutoff artifacts which tend to become large as the quark mass gets small. We show that these effects can be reduced to a negligible level by either introducing the clover term in the action or, as already suggested in the literature, by a suitable choice of the critical mass. Recent simulation data support these conclusions.

hep-lat↗
arXiv2005

A strategy for the computation of m_b including 1/m terms

We consider HQET including the first order correction in 1/m. A strategy for the computation of the b-quark mass is discussed. Only two quantities Phi_1/2 have to be considered in order to match QCD and HQET, since the spin-dependent interaction is easily eliminated due to the spin symmetry of the static theory. Quite simple formulae relate the renormalization group invariant b-quark mass (M_b) to the B-meson mass. All entries in these formulae are non-perturbatively defined and can be computed in the continuum limit of the lattice regularized theory. For the numerically most critical part, we illustrate the cancellation of power divergences by a numerical example. Numerical results for the 1/m correction to M_b, are presented in a companion talk.

hep-lat↗
arXiv2001

Dynamic Critical Behavior of an Extended Reptation Dynamics for Self-Avoiding Walks

We consider lattice self-avoiding walks and discuss the dynamic critical behavior of two dynamics that use local and bilocal moves and generalize the usual reptation dynamics. We determine the integrated and exponential autocorrelation times for several observables, perform a dynamic finite-size scaling study of the autocorrelation functions, and compute the associated dynamic critical exponents $z$. For the variables that describe the size of the walks, in the absence of interactions we find $z \approx 2.2$ in two dimensions and $z\approx 2.1$ in three dimensions. At the $θ$-point in two dimensions we have $z\approx 2.3$.

cond-mat.stat-mech↗
arXiv1999

Bilocal Dynamics for Self-Avoiding Walks

We introduce several bilocal algorithms for lattice self-avoiding walks that provide reasonable models for the physical kinetics of polymers in the absence of hydrodynamic effects. We discuss their ergodicity in different confined geometries, for instance in strips and in slabs. A short discussion of the dynamical properties in the absence of interactions is given.

hep-lat↗