scholarly journals Rotated twisted-mass: a convenient regularization scheme for isospin breaking QCD and QED lattice calculations

2021 ◽  
Vol 57 (9) ◽  
Author(s):  
R. Frezzotti ◽  
G. Gagliardi ◽  
V. Lubicz ◽  
F. Sanfilippo ◽  
S. Simula
Keyword(s):  
Correlation Functions ◽  
Mass Splitting ◽  
Isospin Breaking ◽  
Numerical Application ◽  
Practical Advantage ◽  
Regularization Scheme ◽  
Statistical Fluctuations ◽  
Twisted Mass ◽  
Lattice Calculations

AbstractWe propose a scheme of lattice twisted-mass fermion regularization which is particularly convenient for application to isospin breaking (IB) QCD and QED calculations, based in particular on the so called RM123 approach, in which the IB terms of the action are treated as a perturbation. The main, practical advantage of this scheme is that it allows the calculation of IB effects on some mesonic observables, like e.g. the $$\pi ^+ - \pi ^0$$ π + - π 0 mass splitting, using lattice correlation functions in which the quark and antiquark fields in the meson are regularized with opposite values of the Wilson parameter r. These correlation functions are found to be affected by much smaller statistical fluctuations, with respect to the analogous functions in which quark and antiquark fields are regularized with the same value of r. Two numerical application of this scheme, that we call rotated twisted-mass, within pure QCD and QCD + QED respectively, are also provided for illustration.

scholarly journals Leading isospin-breaking corrections to meson masses on the lattice

2018 ◽  
Vol 175 ◽  
pp. 06002 ◽  
Author(s):  
Davide Giusti ◽  
Vittorio Lubicz ◽  
Guido Martinelli ◽  
Francesco Sanfilippo ◽  
Silvano Simula ◽  
...  
Keyword(s):  
Fine Structure ◽  
Quark Mass ◽  
Light Quark ◽  
Structure Constant ◽  
Mass Splitting ◽  
Fine Structure Constant ◽  
Isospin Breaking ◽  
Decay Constants ◽  
Quark Masses ◽  
Small Parameters

We present a study of the isospin-breaking (IB) corrections to pseudoscalar (PS) meson masses using the gauge configurations produced by the ETM Collaboration with Nf = 2+1+1 dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters [see formula in PDF] and αem, where [see formula in PDF] is the renormalized quark mass and αem the renormalized fine structure constant. We obtain results for the pion, kaon and Dmeson mass splitting; for the Dashen’s theorem violation parameters ϵγ(MM, 2 GeV), ϵπ0 ϵK0(MS, 2 GeV) for the light quark masses [see formula in PDF] for the flavour symmetry breaking parameters R(MS, 2 GeV) and Q(MS, 2 GeV) and for the strong IB effects on the kaon decay constants.

scholarly journals Comments on contact terms and conformal manifolds in the AdS/CFT correspondence

2020 ◽  
Author(s):  
Tadakatsu Sakai ◽  
Masashi Zenkai
Keyword(s):  
Fixed Point ◽  
Correlation Functions ◽  
Equations Of Motion ◽  
Mathematical Structure ◽  
Regularization Scheme ◽  
Anomalous Dimensions ◽  
Geometrical Data ◽  
Conformal Manifolds ◽  
General Setup ◽  
Marginal Deformation

Abstract We study the contact terms that appear in the correlation functions of exactly marginal operators using the AdS/CFT correspondence. It is known that CFT with an exactly marginal deformation requires the existence of the contact terms is crucial for a consistency of with their coefficients having a geometrical interpretation in the context of conformal manifolds. We show that the AdS/CFT correspondence captures properly the mathematical structure of the correlation functions that is expected from the CFT analysis. For this purpose, we employ holographic RG to formulate a most general setup in the bulk for describing an exactly marginal deformation. The resultant bulk equations of motion are nonlinear and solved perturbatively to obtain the on-shell action. We compute three- and four-point functions of the exactly marginal operators using the GKP-Witten prescription, and show that they match with the expected results precisely. It is pointed out that The cut-off surface prescription in the bulk provides us with a regularization scheme for performing a conformal perturbation. serves as a regularization scheme for conformal perturbation theory in the boundary CFT. around a fixed point is regularized by putting a cut-off surface in the bulk. As an application, we examine a double OPE limit of the four-point functions. The anomalous dimensions of double trace operators are written in terms of the geometrical data of a conformal manifold.

scholarly journals QCD factorization for chiral-odd parton quasi- and pseudo-distributions

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Vladimir M. Braun ◽  
Yao Ji ◽  
Alexey Vladimirov
Keyword(s):  
Correlation Functions ◽  
Momentum Space ◽  
Parton Distribution ◽  
Distribution Functions ◽  
Factorization Theorem ◽  
Position Space ◽  
Parton Distribution Functions ◽  
Transversity Distribution ◽  
Qcd Factorization ◽  
Lattice Calculations

Abstract We study chiral-odd quark-antiquark correlation functions suitable for lattice calculations of twist-three nucleon parton distribution functions hL(x) and e(x), and also the twist-two transversity distribution δq(x). The corresponding factorized expressions are derived in terms of the twist-two and twist-three collinear distributions to one-loop accuracy. The results are presented both in position space, as the factorization theorem for Ioffe-time distributions, and in momentum space, for quasi- and pseudo-distributions. We demonstrate that the twist-two part of the hL quasi(pseudo)-distribution can be separated from the twist-three part by virtue of an exact Jaffe-Ji-like relation.

scholarly journals Leading isospin-breaking corrections to pion, kaon, and charmed-meson masses with twisted-mass fermions

2017 ◽  
Vol 95 (11) ◽  
Author(s):  
D. Giusti ◽  
V. Lubicz ◽  
C. Tarantino ◽  
G. Martinelli ◽  
F. Sanfilippo ◽  
...  
Keyword(s):  
Charmed Meson ◽  
Isospin Breaking ◽  
Twisted Mass

scholarly journals $$ \mathcal{N} $$ = 1 Super-Yang-Mills theory on the lattice with twisted mass fermions

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Marc Steinhauser ◽  
André Sternbeck ◽  
Björn Wellegehausen ◽  
Andreas Wipf
Keyword(s):  
Dirac Operator ◽  
Particle Physics ◽  
Finite Lattice ◽  
Mass Splitting ◽  
Perturbative Approach ◽  
Multigrid Algorithm ◽  
Yang Mills ◽  
Twisted Mass ◽  
Mass Degeneracy ◽  
Super Yang Mills Theory

Abstract Super-Yang-Mills theory (SYM) is a central building block for supersymmetric extensions of the Standard Model of particle physics. Whereas the weakly coupled subsector of the latter can be treated within a perturbative setting, the strongly coupled subsector must be dealt with a non-perturbative approach. Such an approach is provided by the lattice formulation. Unfortunately a lattice regularization breaks supersymmetry and consequently the mass degeneracy within a supermultiplet. In this article we investigate the properties of $$ \mathcal{N} $$ N = 1 supersymmetric SU(3) Yang-Mills theory with a lattice Wilson Dirac operator with an additional parity mass, similar as in twisted mass lattice QCD. We show that a special 45° twist effectively removes the mass splitting of the chiral partners. Thus, at finite lattice spacing both chiral and supersymmetry are enhanced resulting in an improved continuum extrapolation. Furthermore, we show that for the non-interacting theory at 45° twist discretization errors of order $$ \mathcal{O}(a) $$ O a are suppressed, suggesting that the same happens for the interacting theory as well. As an aside, we demonstrate that the DDαAMG multigrid algorithm accelerates the inversion of the Wilson Dirac operator considerably. On a 163× 32 lattice, speed-up factors of up to 20 are reached if commonly used algorithms are replaced by the DDαAMG.

scholarly journals HVP contribution of the light quarks to the muon (g - 2) including isospin-breaking corrections with Twisted-Mass fermions

2019 ◽  
Author(s):  
Davide Giusti ◽  
Vittorio Lubicz ◽  
Guido Martinelli ◽  
Francesco Sanfilippo ◽  
Silvano Simula ◽  
...  
Keyword(s):  
Isospin Breaking ◽  
Twisted Mass
Sign in / Sign up

Export Citation Format

Share Document