Thu·Dec 1, 2022Thursday·December 1, 2022

1. 01*

   Towards $K\pi$ scattering with domain-wall fermions at the physical point using distillation

   Nelson Pitanga Lachini🇬🇧 · Peter Boyle🇬🇧 · Felix Erben🇬🇧 · Michael Marshall🇬🇧 · Antonin Portelli🇬🇧

   Resonances play an important role in Standard Model phenomenology. In particular, hadronic resonances feature in $B$ and $D$ decays, which can be central for New Physics searches. Lattice QCD simulations combined with the finite-volume method can nowadays be used to reliably study strongly coupled scattering processes such as $K\pi$ and thus the hadronic resonance $K^{\ast }$. In this work, we approach $K\pi$ scattering on a domain-wall $N_f=2+1$ RBC-UKQCD ensemble at a physical pion mass. We use the distillation method within Grid and Hadrons software to compute sets of operator basis. That allows solving an eigenvalue problem to extract the low-energy finite-volume spectra, which are then translated into scattering information. We update the state of the calculation by reviewing the smearing process, outlining the variational analysis and concluding by showing preliminary data.

   hep-latPoS(2023)·3 citations
2. 02*

   All About the Neutron from Lattice QCD

   Rajan Gupta🇺🇸

   I describe how simulations of lattice QCD using the path integral formulation provide the two basic quantum mechanical properties of QCD, its ground state in which correlation functions are calculated, and Fock state wavefunctions between which matrix elements of operators are calculated. Both constructs are stochastic, so unfortunately one gets no intuitive picture or even a qualitative understanding of what they look like, nevertheless they contain and display all the subtleties of the quantum field theory. Today, these simulations provide many quantities that are impacting phenomenology and experiments. I illustrate the methods and the steps in the analysis using, as examples, three observables: the isovector charges of the nucleon, the contribution of the quark's intrinsic spin to the nucleon spin, and the pion-nucleon sigma term.

   hep-latSciPost Phys.Proc.(2024)·0 citations
3. 03*

   Inclusive semi-leptonic decays of charmed mesons with Möbius domain wall fermions

   Ryan Kellermann🇯🇵 · Alessandro Barone🇬🇧 · Shoji Hashimoto🇯🇵 · Andreas Jüttner🇬🇧 · Takashi Kaneko🇯🇵

   We perform a non-perturbative lattice calculation of the decay rates for inclusive semi-leptonic decays of charmed mesons. In view of the long-standing tension in the determination of the CKM matrix elements $|V_{ub}|$ and $|V_{cb}|$ from exclusive and inclusive processes, recently, the use of lattice QCD has been extended towards the description of inclusive decays. Since the determination of hadronic input parameters from QCD based methods require independent tests, we focus on the charm sector, since it not only offers experimental data, but also well determined CKM parameters. We carry out a pilot lattice simulation for the $D_s\to X_s\ell \nu$ and explore the improvement of existing techniques. Our simulation employs Möbius domain-wall charm and strange quarks whose masses are tuned to be approximately physical and we cover the whole kinematical region. We report on our progress in analyzing different sources of systematic effects, such as the extrapolation of the kernel function chosen for the Chebsyhev approximation as well as the influence on the analysis in the region close to the kinematical limit.

   hep-latPoS(2023)·16 citations
4. 04*

   The spectrum of GUT-like gauge-scalar models

   Elizabeth Dobson🇦🇹 · Axel Maas🇦🇹 · Bernd Riederer🇦🇹

   Past lattice simulations tentatively suggested that the spectrum of observable particles in BSM theories is qualitatively different than perturbatively expected. The discrepancy can be traced back to nontrivial field-theoretical effects arising from the requirement of gauge invariance. A perturbative but gauge-invariant approach working directly with bound states (as proposed by Fröhlich, Morchio and Strocchi) could provide a solution, by allowing composite-state effects to be treated within a perturbative framework. We consider a toy GUT-like theory -- SU(3) Yang-Mills coupled to a scalar `Higgs' in the fundamental representation -- and expand on previous work by providing the most comprehensive spectroscopy to date, including all channels up to spin 2. Our results strongly support the general conclusion that the elementary spectrum is not an adequate proxy for the low-energy spectrum of a GUT, and also suggest a possible analytical approach to BSM model-building via the Fröhlich-Morchio-Strocchi approach.

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

   Progress in calculation of the fourth Mellin moment of the pion light-cone distribution amplitude using the HOPE method

   William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Robert J. Perry🇪🇸 · Yong Zhao🇺🇸

   The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for the calculation of high-energy exclusive processes in quantum chromodynamics. This article describes the progress in the lattice QCD calculation of the fourth Mellin moment of the pion LCDA using a heavy-quark operator product expansion (HOPE).

   hep-lathep-phnucl-thPoS(2023)·2 citations
6. 06*

   Electromagnetic form factors of the proton and neutron from $N_f=2+1$ lattice QCD

   Miguel Salg🇩🇪 · Dalibor Djukanovic🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Konstantin Ottnad🇩🇪 · Hartmut Wittig🇩🇪

   We present results for the electromagnetic form factors of the proton and neutron computed on the Coordinated Lattice Simulations (CLS) ensembles with $N_f=2+1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions and an $\mathcal{O}(a)$-improved conserved vector current. In order to estimate the excited-state contamination, we employ several source-sink separations and apply the summation method. The quark-disconnected diagrams entering the isoscalar quantities are computed explicitly. For this purpose, a stochastic estimation based on the one-end trick is performed, in combination with a frequency-splitting technique and the hopping-parameter expansion. By these means, we obtain a clear signal for the form factors including the quark-disconnected contributions, which have a statistically significant effect on our results. From the $Q^2$-dependence of the form factors, we determine the electric and magnetic charge radii and the magnetic moments of the proton and neutron. The chiral interpolation is carried out by simultaneously fitting the pion mass and $Q^2$-dependence of our form factor data directly to the expressions resulting from covariant chiral perturbation theory including vector mesons. To assess the influence of systematic effects, we average over various cuts in the pion mass and the momentum transfer, as well as over different models for the lattice spacing and finite volume dependence.

   hep-latPoS(2023)·3 citations
7. 07*

   Intermediate window observable for the hadronic vacuum polarization contribution to the muon $g-2$ from O$(a)$ improved Wilson quarks

   Marco Cè🇨🇭 · Antoine Gérardin🇫🇷 · Georg von Hippel🇩🇪 · Renwick J. Hudspith🇩🇪 · Simon Kuberski🇩🇪 · Harvey B. Meyer🇩🇪 · Kohtaroh Miura🇩🇪 · Daniel Mohler🇩🇪 · Konstantin Ottnad🇩🇪 · Srijit Paul🇩🇪 · Andreas Risch🇩🇪 · Teseo San José🇩🇪 · Hartmut Wittig🇩🇪

   Following the publication of the new measurement of the anomalous magnetic moment of the muon, the discrepancy between experiment and the theory prediction from the $g-2$ theory initiative has increased to $4.2\sigma$. Recent lattice QCD calculations predict values for the hadronic vacuum polarization contribution that are larger than the data-driven estimates, bringing the Standard Model prediction closer to the experimental measurement. Euclidean time windows in the time-momentum representation of the hadronic vacuum polarization contribution to the muon $g-2$ can help clarify the discrepancy between the phenomenological and lattice predictions. We present our calculation of the intermediate distance window contribution using $N_{\mathrm{f}}=2+1$ flavors of O$(a)$ improved Wilson quarks. We employ ensembles at six lattice spacings below $0.1$fm and pion masses down to the physical value. We present a detailed study of the continuum limit, using two discretizations of the vector current and two independent sets of improvement coefficients. Our result at the physical point displays a tension of $3.9\sigma$ with a recent evaluation of the intermediate window based on the data-driven method.

   hep-lathep-phPoS(2023)·2 citations
8. 08*

   Strong two-meson decays of light and charmed vector mesons

   Roberto Correa da Silveira🇧🇷 · Fernando E. Serna🇧🇷 · Bruno El-Bennich🇧🇷

   We calculate the strong decay couplings for $\rho \to \pi \pi$, $\varphi \to KK$, $K^{\ast }\to K\pi$ and $D^{\ast }\to D\pi$ in a unified and consistent approach based on the impulse approximation, nonperturbative solutions of the quark-gap equation and the Poincaré invariant Bethe-Salpeter amplitudes of vector and pseudoscalar mesons. In particular, we obtain the coupling $g_{D^{\ast }D\pi }=17.24_{-2.30}^{+3.06}$ in very good agreement with the experimental value by CLEO, which corresponds to a strong effective coupling between heavy vector and pseudoscalar mesons to the pion of $\hat{g}=0.58_{-0.08}^{+0.10}$.

   ↳ hep-phhep-exhep-latnucl-thPRD(2023)·13 citations
9. 09*

   Probabilistic cellular automaton for quantum particle in a potential

   C. Wetterich🇩🇪

   We propose that a quantum particle in a potential in one space dimension can be described by a probabilistic cellular automaton. While the simple updating rule of the automaton is deterministic, the probabilistic description is introduced by a probability distribution over initial conditions. The proposed automaton involves right- and left-movers, jumping from one cell to a neighboring one. They change their direction of motion at each randomly distributed disorder or scattering point. The continuum limit of an infinite number of cells yields a Dirac equation, and in the non-relativistic limit the familiar Schrödinger equation, with potential determined by the spacetime-distribution of scattering points. These equations describe the time evolution of the probabilistic information for the position of the particle. All quantum rules for observables, both for discrete possible measurement values and continuous expectation values, follow from the classical statistical laws.

   ↳ quant-phhep-lathep-th7 citations
10. 10*

    Gauge theory on graphs

    Shuhan Jiang

    In this paper, we provide the notions of connection $1$-forms and curvature $2$-forms on graphs. We prove a Weitzenböck formula for connection Laplacians in this setting. We also define a discrete Yang-Mills functional and study its Euler-Lagrange equations.

    ↳ math.COhep-lat2 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.