相关论文: Perturbative Subtraction Methods
Perturbative coefficients for Wilson loops and the static-quark self-energy are extracted from Monte Carlo simulations at weak coupling. The lattice volumes and couplings are chosen to ensure that the lattice momenta are all perturbative.…
Preliminary results of a calculation of disconnected nucleon electromagnetic factors factors on the lattice are presented. The implementation of the numerical subtraction scheme is outlined. A comparison of results for electric and magnetic…
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.…
Expressions for the Wick contractions contributing to the scalar pion form-factor were computed model-independently in chiral perturbation theory at next-to-leading order. The results reveal correlations amongst the different contractions…
The energy spectrum of a system containing a static quark anti-quark pair is computed for a wide range of source separations using lattice QCD with $N_\mathrm{f}=2+1$ dynamical flavours. By employing a variational method with a basis…
We summarise status and recent results of the European Twisted Mass collaboration (ETMC). The collaboration has generated gauge configurations for three different values of the lattice spacing smaller or equal 0.1 fm and values of the…
A method for computing electromagnetic properties of hadrons in lattice QCD is described and preliminary numerical results are presented. The electromagnetic field is introduced dynamically, using a noncompact formulation. Employing…
The coefficients multiplying the counterterms required for O($a$) improvement of the action and the isovector axial current in lattice QCD are computed non-perturbatively, in the quenched approximation and for bare gauge couplings $g_0$ in…
We consider two-flavor QCD in the lattice regularization with improved Wilson fermions. In this formulation chiral symmetry is explicitly broken at order a and hence the isovector axial currents require improvement as well as a finite…
Following a recent work (briefly reviewed below) we consider temporal fluctuations in the reduced density matrix elements for a coupled system involving a pair of kicked rotors as also one made up of a pair of Harper Hamiltonians. These…
The chiral Lagrangian describing the low-energy behavior of N_f=2+1+1 twisted mass lattice QCD is constructed through O(a^2). In contrast to existing results the effects of a heavy charm quark are consistently removed, leaving behind a…
Recent conceptual, algorithmic and technical advances allow numerical simulations of lattice QCD with Wilson quarks to be performed at significantly smaller quark masses than was possible before. Here we report on simulations of two-flavour…
We present a high order perturbative computation of the renormalization constants Z_V, Z_A and of the ratio Z_P/Z_S for Wilson fermions. The computational setup is the one provided by the RI'-MOM scheme. Three- and four-loop expansions are…
We present the results of a non-perturbative determination of the improvement coefficient $c_\mathrm{V}$ and the renormalisation factor $Z_\mathrm{V}$, which define the renormalised vector current in three-flavour $\mathrm{O}(a)$ improved…
The gradient flow in QCD is treated perturbatively through next-to-next-to-leading order in the strong coupling constant. The evaluation of the relevant momentum and flow-time integrals is described, including various means of validation.…
We derive the asymptotic lattice spacing dependence $a^n[2b_0\bar{g}^2(1/a)]^{\hat{\Gamma}_i}$ relevant for spectral quantities of lattice QCD, when using Wilson, O$(a)$ improved Wilson or Ginsparg-Wilson quarks. We give some examples for…
The modelling of the ultraviolet contributions to the quark determinant in lattice QCD in terms of a small number of Wilson loops is examined. Complete Dirac spectra are obtained for sizeable ensembles of SU(3) gauge fields at $\beta$=5.7…
The effect of an AC perturbation on the shot noise of a fractional quantum Hall fluid is studied both in the weak and the strong backscattering regimes. It is known that the zero-frequency current is linear in the bias voltage, while the…
We discuss a specific cut-off effect which appears in applying the non-perturbative RI/MOM scheme to compute the renormalization constants. To illustrate the problem a Dirac operator satisfying the Ginsparg-Wilson relation is used, but the…
We develop a generalization of low-mode averaging in which the number of low quark modes of the Dirac operator required for a constant variance reduction can be kept independent of the volume by exploiting their local coherence. Typically…