Thu·Nov 11, 2021Thursday·November 11, 2021

1. 01*

   Infinite volume, three-body scattering formalisms in the presence of bound states

   Sebastian M. Dawid🇺🇸

   Strong interactions produce a rich spectrum of resonances that decay into three or more hadrons. Understanding their phenomenology requires a theoretical framework to extract parameters fromexperimental data and Lattice QCD simulations of hadron scattering. Two classes of relativistic three-body approaches are currently being pursued: the EFT-based and unitarity-based one. We consider a model of relativistic three-body scattering with an S-wave bound state in the two-body sub-channel using both formalisms. We present and discuss numerical solutions for the multi-hadron scattering amplitudes in different kinematical regions, obtained from integral equationsof the EFT-based approach. The connection of our work to the ongoing program of computingthe three-body spectrum from the lattice is highlighted. Finally, we show how to generalizethe unitarity-based framework to include all relevant open channels, discuss the nonphysicalsingularities near the physical region, and show how to eliminate them in a simple case.

   hep-latnucl-thPoS(2022)·5 citations
2. 02*

   Lee-Yang edge singularities in 2+1 flavor QCD with imaginary chemical potential

   Guido Nicotra🇩🇪 · Petros Dimopoulos🇮🇹 · Lorenzo Dini🇩🇪 · Francesco Di Renzo🇮🇹 · Jishnu Goswami🇩🇪 · Christian Schmidt🇩🇪 · Simran Singh🇮🇹 · Kevin Zambello🇮🇹 · Felix Ziesche🇩🇪

   We present results of the location of the closest singularities in the complex chemical potential plane using a novel method. These results are obtained with (2+1)-flavor of highly improved staggered quarks (HISQ) on lattices with temporal extent of Nt=4,6. We show that the scaling is consistent with the expected scaling of the Lee-Yang edge singularities in the vicinity of the Roberge-Weiss (RW) transition. We determine various non-universal parameters using 3D Ising model scaling functions that map QCD in the scaling region of the RW transition. Furthermore, as a preliminary result we discuss how the Lee-Yang edge singularity can be used to probe the chiral phase transition in QCD. The singularity obtained close to the chiral phase transition temperature Tc seems to be in agreement with the expected scaling of the Lee-Yang edge singularity. As an outlook, we discuss the scaling of the Lee-Yang edge singularity in the vicinity of a possible critical end point in QCD, at even lower temperatures. In the future, such a scaling analysis might hint on the existence and the location of the critical end point. The work presented here is a part of an ongoing project of Bielefeld Parma joint collaboration.

   hep-latPoS(2022)·15 citations
3. 03*

   Properties of the $\eta$ and ${\eta }^{\prime }$ mesons: Masses, decay constants and gluonic matrix elements

   Gunnar S. Bali🇩🇪 · Sara Collins🇩🇪 · Jakob Simeth🇩🇪

   We present results for the $\eta$ and ${\eta }^{\prime }$ masses and their four independent decay constants at the physical point as well as their anomalous gluonic matrix elements $a_{{\eta }^{(\prime )}}$. The chiral and continuum limit extrapolation is performed on twenty-one $N_f=2+1$ Coordinated Lattice Simulations (CLS) ensembles with non-perturbatively improved Wilson fermions at four different lattice spacings and along two trajectories in the quark mass plane, including one ensemble very close to physical quark masses. For the first time the decay constants are determined directly from the axialvector matrix elements without model assumptions. This allows us to study their QCD scale dependence and to determine all low-energy constants contributing at next-to-leading order in large-$N_c$ ChPT at a well defined QCD renormalization scale. We also discuss higher excited states in the $1400\mathrm{MeV}$ region.

   hep-latPoS(2021)·2 citations
4. 04*

   Supercurrent Renormalization in $\mathcal{N}=1$ Supersymmetric Yang-Mills Theory

   Georg Bergner🇩🇪 · Marios Costa🇨🇾 · Haralambos Panagopoulos🇨🇾 · Stefano Piemonte🇩🇪 · Apostolos Skouroupathis🇨🇾 · Ivan Soler🇩🇪 · Gregoris Spanoudes🇨🇾

   In this work we study the renormalization of the SUSY Noether current in Supersymmetric $\mathcal{N}$ = 1 Yang-Mills (SYM) theory on the lattice. In particular, we study the mixing of the current with all other compatible operators of dimension 7/2 and 5/2, leading from the lattice-regularized to the $\overline{\mathrm{MS}}$-renormalized operator basis. We perform our task in two ways: (a) We compute, in dimensional regularization, the conversion factors relating the $\overline{\mathrm{MS}}$ scheme to an intermediate gauge-invariant coordinate-space scheme. In this second scheme, renormalization can be performed via lattice simulations. This could help to investigate the breaking of SUSY on the lattice and strategies towards simulations of supersymmetric QCD. Here we present some preliminary numerical results. (b) We use lattice perturbation theory and compute, to one loop, various two- and three-point functions. We consider mixing with all relevant gauge-noninvariant operators, which contain also ghost fields.

   hep-latPoS(2022)·2 citations
5. 05*

   $B_s\to D_s^{(\ast )}$ form factors from lattice QCD with $N_f=2$ Wilson-clover quarks

   Benoît Blossier🇫🇷 · Pierre Henri Cahue🇫🇷 · Jochen Heitger🇩🇪 · Simone La Cesa🇫🇷 · Jan Neuendorf🇫🇷 · Savvas Zafeiropoulos🇫🇷

   We report on a two-flavour lattice QCD determination of the $B_s\to D_s$ and $B_s\to D_s^{\ast }$ transitions, which in the heavy quark limit can be parameterised by the form factors $\mathcal{G}$, and $h_{{\text{A}}_1}$, $h_{{\text{A}}_2}$ and $h_{{\text{A}}_3}$. In the search of New Physics through tests of lepton-flavour universality, $B_s$ decay channels are complementary to $B$ decays and widely studied at $B$ factories and LHCb. The purpose of our study is to explore a suitable method to extract form factors associated with $b\to c$ currents from lattice QCD. In particular, we present numerical results for $\mathcal{G}$ and $h_{{\text{A}}_1}$.

   hep-latPoS(2022)·3 citations
6. 06*

   Improved topological sampling for lattice gauge theories

   David Albandea🇪🇸 · Pilar Hernández🇪🇸 · Alberto Ramos🇪🇸 · Fernando Romero-López🇺🇸

   Standard sampling algorithms for lattice QCD suffer from topology freezing (or critical slowing down) when approaching the continuum limit, thus leading to poor sampling of the distinct topological sectors. I will present a modified Hamiltonian Monte Carlo (HMC) algorithm that triggers topological sector jumps during the assembly of Markov chain of lattice configurations. We study its performance in the 2D Schwinger model and compare it to alternative methods, such as fixing topology or master field. We then briefly discuss the difficulties of the algorithm in a SU(2) gauge model in 4D.

   hep-latPoS(2022)·4 citations

* 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.