Date: Thu, 28 Mar 13 00:06:26 GMT Subject: hep-lat daily 3 new + 1 crosses received by eprepget ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ Send any comments regarding submissions directly to submitter. ------------------------------------------------------------------------------ Archives at http://arxiv.org/ To unsubscribe, e-mail To: hep-lat@arXiv.org, Subject: cancel ------------------------------------------------------------------------------ received by eprepget from Tue 26 Mar 13 20:00:00 GMT to Wed 27 Mar 13 20:00:00 GMT ------------------------------------------------------------------------------ \\ arXiv:1303.6776 Date: Wed, 27 Mar 2013 10:04:02 GMT (1569kb) Title: Perturbatively improving RI-MOM renormalization constants Authors: M. Constantinou, M. Costa, M. Gockeler, R. Horsley, H. Panagopoulos, H. Perlt, P. E. L. Rakow, G. Schierholz and A. Schiller Categories: hep-lat Comments: 20 pages, 11 figures, 4 tables Report-no: DESY 13-046, Edinburgh 2013/03, Liverpool LTH 972 \\ The determination of renormalization factors is of crucial importance in lattice QCD. They relate the observables obtained on the lattice to their measured counterparts in the continuum in a suitable renormalization scheme. Therefore, they have to be computed as precisely as possible. A widely used approach is the nonperturbative Rome-Southampton method. It requires, however, a careful treatment of lattice artifacts. In this paper we investigate a method to suppress these artifacts by subtracting one-loop contributions to renormalization factors calculated in lattice perturbation theory. We compare results obtained from a complete one-loop subtraction with those calculated for a subtraction of contributions proportional to the square of the lattice spacing. \\ ( http://arxiv.org/abs/1303.6776 , 1569kb) ------------------------------------------------------------------------------ \\ arXiv:1303.6816 Date: Wed, 27 Mar 2013 12:59:15 GMT (122kb) Title: Extended hadron and two-hadron operators of definite momentum for spectrum calculations in lattice QCD Authors: C. Morningstar, J. Bulava, B. Fahy, J. Foley, Y.C. Jhang, K.J. Juge, D. Lenkner, C.H. Wong Categories: hep-lat Comments: 19 pages, 7 figures, 21 tables \\ Multi-hadron operators are crucial for reliably extracting the masses of excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo calculations. The construction of multi-hadron operators with significant coupling to the lowest-lying states of interest involves combining single hadron operators of various momenta. The design and implementation of large sets of spatially-extended single-hadron operators of definite momentum and their combinations into two-hadron operators are described. The single hadron operators are all assemblages of gauge-covariantly-displaced, smeared quark fields. Group-theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. Tests of these operators on 24^3 x 128 and 32^3 x 256 anisotropic lattices using a stochastic method of treating the low-lying modes of quark propagation which exploits Laplacian Heaviside quark-field smearing are presented. The method provides reliable estimates of all needed correlations, even those that are particularly difficult to compute, such as eta eta -> eta eta in the scalar channel, which involves the subtraction of a large vacuum expectation value. A new glueball operator is introduced, and the evaluation of the mixing of this glueball operator with a quark-antiquark operator, pi-pi, and eta-eta operators is shown to be feasible. \\ ( http://arxiv.org/abs/1303.6816 , 122kb) ------------------------------------------------------------------------------ \\ arXiv:1303.6818 Date: Wed, 27 Mar 2013 13:02:14 GMT (903kb) Title: Nucleon Structure using lattice QCD Authors: C. Alexandrou (Univ. of Cyprus and Cyprus Inst.), M. Constantinou (Univ. of Cyprus), V.Drach (DESY-Zeuthen), K. Hatziyiannakou (Univ. of Cyprus), K. Jansen (DESY-Zeuthen & Univ. of Cyprus), C. Kallidonis (Univ. of Cyprus & Cyprus Insti.), G.Koutsou (Cyprus Inst.), T. Leontiou (Frederick Univ.) and A. Vaquero (Cyprus Inst.) Categories: hep-lat hep-ph nucl-ex nucl-th Comments: Invited talk at the 3rd Workshop on the QCD Structure of the Nucleon (QCD-N'12), 22-26 October 2012, Bilbao, Spain. 8 pages & 14 figures Report-no: DESY 13-047, SFB/CPP-13-22 \\ A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods applied for their study, including approaches to evaluate the disconnected contributions. Results on the spin carried by the quarks in the nucleon are also presented. \\ ( http://arxiv.org/abs/1303.6818 , 903kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- ------------------------------------------------------------------------------ \\ arXiv:1303.6858 (*cross-listing*) Date: Wed, 27 Mar 2013 15:19:50 GMT (2415kb,D) Title: The (2+1)-d U(1) Quantum Link Model Masquerading as Deconfined Criticality Authors: D. Banerjee, F.-J. Jiang, P. Widmer, U.-J. Wiese Categories: cond-mat.str-el hep-lat quant-ph Comments: 4.5 pages, 6 figures \\ The $(2+1)$-d U(1) quantum link model is a gauge theory, amenable to quantum simulation, with a spontaneously broken SO(2) symmetry emerging at a quantum phase transition. Its low-energy physics is described by a $(2+1)$-d $\RP(1)$ effective field theory, perturbed by a dangerously irrelevant SO(2) breaking operator, which prevents the interpretation of the emergent pseudo-Goldstone boson as a dual photon. At the quantum phase transition, the model mimics some features of deconfined quantum criticality, but remains linearly confining. Deconfinement only sets in at high temperature. \\ ( http://arxiv.org/abs/1303.6858 , 2415kb) %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- For subscribe options to combined physics archives, e-mail To: physics@arXiv.org, Subject: subscribe ----------------------------------------------------------------------------- For help on viewing and making submissions, see http://arXiv.org/help/ For a list of archive mirror sites, see http://arXiv.org/servers.html ----------------------------------------------------------------------------- Third-party submissions cause excessive problems. Author self-submissions are exceedingly preferred. E-mail submissions have been discontinued in favor of better support for Web submissions. 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