Date: Fri, 27 Sep 19 00:31:49 GMT Subject: hep-lat daily 1 new + 1 crosses received by eprepget DONATE to arXiv: Please join the Simons Foundation and our generous member organizations in supporting arXiv during our giving campaign September 23-27. 100% of your contribution will fund improvements and new initiatives to benefit arXiv's global scientific community. Donate: https://bit.ly/arXivDONATE6 ------------------------------------------------------------------------------ ------------------------------------------------------------------------------ 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 from Wed 25 Sep 19 18:00:00 GMT to Thu 26 Sep 19 18:00:00 GMT ------------------------------------------------------------------------------ \\ arXiv:1909.12253 Date: Thu, 26 Sep 2019 16:58:44 GMT (595kb,D) Title: Finite size and cut-off effects on the Roberge-Weiss transition in $N_\text{f}=2$ QCD with Staggered fermions Authors: Owe Philipsen and Alessandro Sciarra Categories: hep-lat Comments: 13 pages, 8 figures \\ In the absence of a genuine solution to the sign problem, lattice studies at imaginary quark chemical potential are an important tool to constrain the QCD phase diagram. We calculate the values of the tricritical quark masses in the Roberge-Weiss plane, $\mu=\imath\pi T/3$, which separate mass regions with chiral and deconfinement phase transitions from the intermediate region, for QCD with $N_\text{f}=2$ unimproved staggered quarks on $N_\tau=6$ lattices. A quantitative measure for the quality of finite size scaling plots is developed, which significantly reduces the subjective judgement required for fitting. We observe that larger aspect ratios are necessary to unambiguously determine the order of the transition than at $\mu=0$. Comparing with previous results from $N_\tau=4$ we find a $\sim50$% reduction in the light tricritical pion mass. The heavy tricritical pion mass stays roughly the same, but is too heavy to be resolved on $N_\tau=6$ lattices and thus equally afflicted with cut-off effects. Further comparison with other discretizations suggests that current cut-off effects on the light critical masses are likely to be larger than $\sim100$%, implying a drastic shrinking of the chiral first-order region to possibly zero. \\ ( https://arxiv.org/abs/1909.12253 , 595kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- ------------------------------------------------------------------------------ \\ arXiv:1909.12234 (*cross-listing*) Date: Thu, 26 Sep 2019 16:30:08 GMT (2320kb,D) Title: Multigrid deflation for Lattice QCD Authors: Eloy Romero and Andreas Stathopoulos and Kostas Orginos Categories: math.NA cs.NA hep-lat \\ Computing the trace of the inverse of large matrices is typically addressed through statistical methods. Deflating out the lowest eigenvectors or singular vectors of the matrix reduces the variance of the trace estimator. This work summarizes our efforts to reduce the computational cost of computing the deflation space while achieving the desired variance reduction for Lattice QCD applications. Previous efforts computed the lower part of the singular spectrum of the Dirac operator by using an eigensolver preconditioned with a multigrid linear system solver. Despite the improvement in performance in those applications, as the problem size grows the runtime and storage demands of this approach will eventually dominate the stochastic estimation part of the computation. In this work, we propose to compute the deflation space in one of the following two ways. First, by using an inexact eigensolver on the Hermitian, but maximally indefinite, operator $A \gamma_5$. Second, by exploiting the fact that the multigrid prolongator for this operator is rich in components toward the lower part of the singular spectrum. We show experimentally that the inexact eigensolver can approximate the lower part of the spectrum even for ill-conditioned operators. Also, the deflation based on the multigrid prolongator is more efficient to compute and apply, and, despite its limited ability to approximate the fine level spectrum, it obtains similar variance reduction on the trace estimator as deflating with approximate eigenvectors from the fine level operator. \\ ( https://arxiv.org/abs/1909.12234 , 2320kb) %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% ------------------------------------------------------------------------------ \\ arXiv:1807.10064 (*cross-listing*) replaced with revised version Thu, 26 Sep 2019 10:56:56 GMT (627kb) Title: Renormalon-free definition of the gluon condensate within the large-$\beta_0$ approximation Authors: Hiroshi Suzuki and Hiromasa Takaura Categories: hep-ph hep-lat hep-th Comments: 24 pages, 7 figures. The final version to appear in PTEP Report-no: KYUSHU-HET-185 \\ ( https://arxiv.org/abs/1807.10064 , 627kb) ------------------------------------------------------------------------------ \\ arXiv:1905.00026 (*cross-listing*) replaced with revised version Thu, 26 Sep 2019 09:35:57 GMT (25kb,D) Title: A safe CFT at large charge Authors: Domenico Orlando, Susanne Reffert and Francesco Sannino Categories: hep-th hep-lat hep-ph Comments: 18 pages, published version \\ ( https://arxiv.org/abs/1905.00026 , 25kb) ------------------------------------------------------------------------------ \\ arXiv:1906.05766 (*cross-listing*) replaced with revised version Thu, 26 Sep 2019 17:48:13 GMT (452kb,D) Title: Chromopolarizabilities of bottomonia from the $\Upsilon(2S,3S,4S) \to \Upsilon(1S,2S)\pi\pi$ transitions Authors: Yun-Hua Chen, Feng-Kun Guo Categories: hep-ph hep-ex hep-lat nucl-th Comments: 14 pages, 3 figures, more discussions added Journal-ref: Phys. Rev. D 100, 054035 (2019) DOI: 10.1103/PhysRevD.100.054035 \\ ( https://arxiv.org/abs/1906.05766 , 452kb) ------------------------------------------------------------------------------ \\ arXiv:1906.07005 (*cross-listing*) replaced with revised version Thu, 26 Sep 2019 09:25:52 GMT (2534kb,D) Title: $\mathbb{Z}_N$ gauge theories coupled to topological fermions: QED$_2$ with a quantum-mechanical $\theta$ angle Authors: G. Magnifico, D. Vodola, E. Ercolessi, S. P. Kumar, M. M\"uller, A. Bermudez Categories: cond-mat.quant-gas cond-mat.str-el hep-lat hep-th quant-ph Comments: 17 pages, 6 figures. Contains part of the material of version v1 of arXiv:1804.10568, left out in subsequent versions, and not included in the published article Journal-ref: Phys. Rev. B 100, 115152 (2019) DOI: 10.1103/PhysRevB.100.115152 \\ ( https://arxiv.org/abs/1906.07005 , 2534kb) %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- 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/