Date: Wed, 27 Mar 19 00:32:26 GMT Subject: hep-lat daily 2 new + 3 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 Mon 25 Mar 19 18:00:00 GMT to Tue 26 Mar 19 18:00:00 GMT ------------------------------------------------------------------------------ \\ arXiv:1903.10591 Date: Mon, 25 Mar 2019 20:36:57 GMT (536kb,AD) Title: Electromagnetic finite-size effects to the hadronic vacuum polarization Authors: J. Bijnens, J. Harrison, N. Hermansson-Truedsson, T. Janowski, A. J\"uttner, and A. Portelli Categories: hep-lat hep-ph Comments: 42 pages, 11 figures \\ In order to reduce the current hadronic uncertainties in the theory prediction for the anomalous magnetic moment of the muon, lattice calculations need to reach sub-percent accuracy on the hadronic-vacuum-polarization contribution. This requires the inclusion of $\mathcal{O}(\alpha)$ electromagnetic corrections. The inclusion of electromagnetic interactions in lattice simulations is known to generate potentially large finite-size effects suppressed only by powers of the inverse spatial extent. In this paper we derive an analytic expression for the $\mathrm{QED}_{\mathrm{L}}$ finite-volume corrections to the two-pion contribution to the hadronic vacuum polarization at next-to-leading order in the electromagnetic coupling in scalar QED. The leading term is found to be of order $1/L^{3}$ where $L$ is the spatial extent. A $1/L^{2}$ term is absent since the current is neutral and a photon far away thus sees no charge and we show that this result is universal. Our analytical results agree with results from the numerical evaluation of loop integrals as well as simulations of lattice scalar $U(1)$ gauge theory with stochastically generated photon fields. In the latter case the agreement is up to exponentially suppressed finite-volume effects. For completeness we also calculate the hadronic vacuum polarization in infinite volume using a basis of 2-loop master integrals. \\ ( https://arxiv.org/abs/1903.10591 , 536kb) ------------------------------------------------------------------------------ \\ arXiv:1903.11006 Date: Tue, 26 Mar 2019 16:46:19 GMT (1203kb,D) Title: Spectral properties of light and charm mesons from $N_f=2+1$ anisotropic lattice QCD Authors: Ryan Quinn, Jonas Glesaaen, Alexander Rothkopf, Jon-Ivar Skullerud Categories: hep-lat hep-ph Comments: 6 pages, 7 figures, based on poster presented at the XIIIth Quark Confinement and the Hadron Spectrum Conference 2018, Maynooth, Ireland \\ We compute temporal correlators and spectral functions for light, open charm and charmonium mesons in the pseudoscalar and vector channel for a range of temperatures below and above the deconfinement transition. The study is carried out using anisotropic lattice QCD with 2+1 dynamical flavours, $a_s=0.123\,$fm and $a_s/a_\tau=3.5$. The high-temperature results are benchmarked by comparing them to reconstructed correlators obtained by direct summation of the zero temperature correlator. We use two Bayesian methods to reconstruct the spectral functions: the maximum entropy method and the more recent BR method. \\ ( https://arxiv.org/abs/1903.11006 , 1203kb) %-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%-%- ------------------------------------------------------------------------------ \\ arXiv:1903.09672 (*cross-listing*) Date: Fri, 22 Mar 2019 18:38:47 GMT (81kb) Title: Large-$N_c$ and Large-$N_F$ Limits of SU($N_c$) Gauge Theories with Fermions in Different Representations Authors: Sudhakantha Girmohanta, Thomas A. Ryttov, and Robert Shrock Categories: hep-th hep-lat hep-ph Comments: 18 pages, RevTex Report-no: YITP-SB-2019-5 \\ We present calculations of certain limits of scheme-independent series expansions for the anomalous dimensions of gauge-invariant fermion bilinear operators and for the derivative of the beta function at an infrared fixed point in SU($N_c$) gauge theories with fermions transforming according to two different representations. We first study a theory with $N_f$ fermions in the fundamental representation and $N_{f'}$ fermions in the adjoint or symmetric or antisymmetric rank-2 tensor representation, in the limit $N_c \to \infty$, $N_f \to \infty$ with $N_f/N_c$ fixed and finite. We then study the $N_c \to \infty$ limit of a theory with fermions in the adjoint and rank-2 symmetric or antisymmetric tensor representations. \\ ( https://arxiv.org/abs/1903.09672 , 81kb) ------------------------------------------------------------------------------ \\ arXiv:1903.10844 (*cross-listing*) Date: Tue, 26 Mar 2019 12:58:06 GMT (936kb,D) Title: Single pseudoscalar meson pole and pion box contributions to the anomalous magnetic moment of the muon Authors: Gernot Eichmann, Christian S. Fischer, Esther Weil, Richard Williams Categories: hep-ph hep-lat Comments: 11 pages, 9 figures \\ We present results for single pseudoscalar meson pole contributions and pion box contributions to the hadronic light-by-light (LBL) correction of the muon's anomalous magnetic moment. We follow the recently developed dispersive approach to LBL, where these contributions are evaluated with intermediate mesons on-shell. However, the space-like electromagnetic and transition form factors are not determined from analytic continuation of time-like data, but directly calculated within the functional approach to QCD using Dyson-Schwinger and Bethe-Salpeter equations. This strategy allows for a systematic comparison with a strictly dispersive treatment and also with recent results from lattice QCD. Within error bars, we obtain excellent agreement for the pion electromagnetic and transition form factor and the resulting contributions to LBL. In addition, we present results for the $\eta$ and $\eta'$ pole contributions and discuss the dynamical effects in the $\eta-\eta'$ mixing due to the strange quarks. Our result for the total pseudoscalar pole contributions is $a_\mu^{\text{PS-pole}} = 91.6 \,(1.9) \times 10^{-11}$ and for the pion-box contribution we obtain $a_\mu^{\pi-\text{box}} = -16.6 \,(1)(7) \times 10^{-11}$. \\ ( https://arxiv.org/abs/1903.10844 , 936kb) ------------------------------------------------------------------------------ \\ arXiv:1903.11013 (*cross-listing*) Date: Tue, 26 Mar 2019 16:53:11 GMT (23kb) Title: Strong LHCb evidence for supporting the existence of hidden-charm molecular pentaquarks Authors: Rui Chen, Xiang Liu, Zhi-Feng Sun, and Shi-Lin Zhu Categories: hep-ph hep-ex hep-lat nucl-th Comments: 4 pages, 1 table and 1 figure \\ In 26 March 2019, at the Rencontres de Moriond QCD conference, the LHCb Collaboration reported the observation of new pentaquarks, namely $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$. Within the framework of one-boson-exchange (OBE) model, our study indicates that these hidden-charm states are interpreted as loosely bound $\Sigma_c\bar{D}$ with $(I=1/2,J=1/2)$, $\Sigma_c\bar{D}^*$ with $(I=1/2,J=1/2)$ and $\Sigma_c\bar{D}^*$ with $(I=1/2,J=3/2)$, respectively. The current measurement strongly supports the molecular hidden-charm pentaquarks. Thus, this discovery by LHCb, we believe, must become a milestone of the exploration of the multiquark matter. \\ ( https://arxiv.org/abs/1903.11013 , 23kb) %%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%%--%% %%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%---%%%--- 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/