HEP Lattice·hep-lat
13 papers—11 primary·2 cross-listed·reconstructed*
Junichi Noaki · RBC Collaboration
We give a progress report of our lattice calculation of direct and indirect CP violation in kaon decays, parametrized as and , which require non-perturbative calculation of the matrix elements of the Standard Model effective Hamiltonian.
Junichi Noaki · RBC Collaboration
We give a progress report of our new GeV quenched calculation of kaon matrix elements with domain-wall fermion and DBW2 gauge action. Our smaller lattice spacing allows us to address the effect of charmed quark on the lattice. We show preliminary results of renormalized non-perturbatively and matrix elements.
Y. Mori🇯🇵 · V. Bornyakov🇷🇺 · H. Ichie🇷🇺 · Y. Koma🇩🇪 · M. Polikarpov🇷🇺 · G. Schierholz🇩🇪 · H. Stüben🇩🇪 · T. Suzuki🇯🇵
We study the flux tube profile in the baryonic system in full QCD at finite temperature on lattice. We fix the maximally Abelian gauge and measure the monopole and the photon parts of the Abelian action density, the color electric field and the monopole current on both sides of the finite temperature transition. We demonstrate the disappearance of the flux tube in the high temperature phase.
K. Sasaki🇯🇵 · S. Sasaki🇯🇵 · T. Hatsuda (Univ. of Tokyo)🇯🇵 · M. Asakawa (Kyoto Univ.)🇯🇵
We study excited states of the nucleon in quenched lattice QCD with the spectral analysis using the maximum entropy method. Our simulations are performed on three lattice sizes , and , at to address the finite volume issue. We find a significant finite volume effect on the mass of the Roper resonance for light quark masses. After removing this systematic error, its mass becomes considerably reduced toward the direction to solve the level order puzzle between the Roper resonance and the negative-parity nucleon .
Takashi Umeda🇯🇵 · Kouji Nomura🇯🇵 · Hideo Matsufuru🇯🇵
We study the light hadron correlators near the deconfining transition by extracting the spectral function on quenched anisotropic lattices. We adopt the method successfully applied to the charmonium systems: the use of the smeared operators and the analysis method which is composed of the maximum entropy method and the fitting assuming several forms. The numerical simulations are performed on lattices of GeV and , with the clover quark around the strange quark mass. Towards applications to the plasma phase, we check the reliability of our procedure by examining how the results for the correlators below () changes under variation of input parameters such as the smearing function.
Ralf Hofmann🇩🇪 · Ion-Olimpiu Stamatescu🇩🇪
We use a model based on the hopping parameter expansion to study QCD at large . We find interesting behavior in the region expected to show flavor-color locking.
K.J. Juge🇨🇭 · J. Kuti🇺🇸 · F. Maresca🇮🇪 · C. Morningstar🇺🇸 · M. Peardon🇮🇪
The excitations of gluonic flux tube in a periodic lattice are examined. Monte Carlo simulations from an anisotropic lattice are presented and the comparison with effective string models is discussed.
A. Shindler🇩🇪 · M. Guagnelli🇮🇹 · K. Jansen🇩🇪 · F. Palombi🇮🇹 · R. Petronzio🇮🇹 · I. Wetzorke (ZeRo collaboration)🇩🇪
We compute non-perturbatively the evolution of the twist-2 operators corresponding to the average momentum of non-singlet quark densities. The calculation is based on a finite-size technique, using the Schrödinger Functional, in quenched QCD. We find that a careful choice of the boundary conditions, is essential, for such operators, to render possible the computation. As a by-product we apply the non-perturbatively computed renormalization constants to available data of bare matrix elements between nucleon states.
R.Brower🇺🇸 · S.Chandrasekharan🇺🇸 · S.Riederer🇨🇭 · U.-J.Wiese🇨🇭
D-theory is an alternative non-perturbative approach to quantum field theory formulated in terms of discrete quantized variables instead of classical fields. Classical scalar fields are replaced by generalized quantum spins and classical gauge fields are replaced by quantum links. The classical fields of a d-dimensional quantum field theory reappear as low-energy effective degrees of freedom of the discrete variables, provided the (d+1)-dimensional D-theory is massless. When the extent of the extra Euclidean dimension becomes small in units of the correlation length, an ordinary d-dimensional quantum field theory emerges by dimensional reduction. The D-theory formulation of scalar field theories with various global symmetries and of gauge theories with various gauge groups is constructed explicitly and the mechanism of dimensional reduction is investigated.
We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the improved current. We calculate form factor for pion masses down to . We compare the mean square radius for the pion extracted from our form factors to the value obtained from the 'Bethe Salpeter amplitude'. Using (quenched) chiral perturbation theory, we extrapolate our results towards the physical pion mass.
O. Oliveira🇵🇹 · P. J. Silva🇵🇹
An algorithm for gauge fixing to the minimal Landau gauge in lattice QCD is described. The method, a combination of an evolutionary algorithm with a steepest descent method, is able to solve the problem of the nonperturbative gauge fixing. The performance of the combined algorithm is investigated on , , and , , lattice SU(3) gauge configurations.
Rainer Sommer (DESY Zeuthen and CERN)🇩🇪
We give an introduction to the problems faced on the way to a reliable lattice QCD computation of B-physics matrix elements. In particular various approaches for dealing with the large scale introduced by the heaviness of the b-quark are mentioned and promising recent achievements are described. We present perspectives for future developments.
F. Sannino (Nordita)🇸🇪 · M. Shifman (Minnesota U., Theor. Phys. Inst.)🇺🇸
We construct effective Lagrangians of the Veneziano-Yankielowicz (VY) type for two non-supersymmetric theories which are orientifold daughters of supersymmetric gluodynamics (containing one Dirac fermion in the two-index antisymmetric or symmetric representation of the gauge group). Since the parent and daughter theories are planar equivalent, at N\to\infty the effective Lagrangians in the orientifold theories basically coincide with the bosonic part of the VY Lagrangian. We depart from the supersymmetric limit in two ways. First, we consider finite (albeit large) values of N. Then 1/N effects break supersymmetry. We suggest seemingly the simplest modification of the VY Lagrangian which incorporates these 1/N effects, leading to a non-vanishing vacuum energy density. We analyze the spectrum of the finite-N non-supersymmetric daughters. For N=3 the two-index antisymmetric representation (one flavor) is equivalent to one-flavor QCD. We show that in this case the scalar quark-antiquark state is heavier than the corresponding pseudoscalar state, `` eta' ''. Second, we add a small fermion mass term. The fermion mass term breaks supersymmetry explicitly. The vacuum degeneracy is lifted. The parity doublets split. We evaluate the splitting. Finally, we include the theta-angle and study its implications.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.