Tue·Nov 29, 2022Tuesday·November 29, 2022

1. 01*

   Toward nuclear physics from lattice QCD on quantum computers

   Arata Yamamoto🇯🇵 · Takumi Doi🇯🇵

   One of the ultimate missions of lattice QCD is to simulate atomic nuclei from the first principle of the strong interaction. This is an extremely hard task for the current computational technology, but might be reachable in coming quantum computing era. In this paper, we discuss the computational complexities of classical and quantum simulations of lattice QCD. It is shown that the quantum simulation scales better as a function of a nucleon number and thus will outperform for large nuclei.

   hep-latnucl-thquant-phPTEP(2024)·10 citations
2. 02*

   Density of states techniques for fermion worldlines

   Christof Gattringer🇦🇹

   Worldline representations were established as a powerful tool for studying bosonic lattice field theories at finite density. For fermions, however, the worldlines still may carry signs that originate from the Dirac algebra and from the Grassmann nature of the fermion fields. We show that a density of states approach can be set up to deal with this remaining sign problem, where finite density is implemented in a canonical approach by working with a fixed winding number of the fermion worldlines. We discuss the approach in detail and show first results of a numerical implementation in 2 dimensions.

   hep-latcond-mat.str-elPoS(2023)·1 citation
3. 03*

   Glueball spectroscopy in lattice QCD using gradient flow

   Keita Sakai🇯🇵 · Shoichi Sasaki🇯🇵

   Removing ultraviolet noise from the gauge fields is necessary for glueball spectroscopy in lattice QCD. It is known that the Yang-Mills gradient flow method is an alternative approach instead of link smearing or link fuzzing in various aspects. In this work we study the application of the gradient flow technique to the construction of the extended glueball operators. We examine a simple application of the gradient flow method, which has some problems in glueball mass calculations at large flow time because of its nature of diffusion in space-time. To avoid this problem, the spatial links are evolved by the ``spatial gradient flow'', that is defined to restrict the diffusion to spatial directions only. We test the spatial gradient flow in calculations of glueball two-point functions and Wilson loops as a new smearing method, and then discuss its efficiency in comparison with the original gradient flow method and the conventional method. Furthermore, to demonstrate the feasibility of our proposed method, we determine the masses of the three lowest-lying glueball states, corresponding to the $0^{++}$, $2^{++}$ and $0^{-+}$ glueballs, in the continuum limit in the pure Yang-Mills theory.

   hep-latPRD(2023)·17 citations
4. 04*

   Deflated Multigrid Multilevel Monte Carlo

   Andreas Frommer🇩🇪 · Gustavo Ramirez-Hidalgo🇩🇪

   In lattice QCD, the trace of the inverse of the discretized Dirac operator appears in the disconnected fermion loop contribution to an observable. As simulation methods get more and more precise, these contributions become increasingly important. Hence, we consider here the problem of computing the trace $\mathrm{tr}(D^{-1})$, with $D$ the Dirac operator. The Hutchinson method, which is very frequently used to stochastically estimate the trace of a function of a matrix, approximates the trace as the average over estimates of the form $x^H{D}^{-1}x$, with the entries of the vector $x$ following a certain probability distribution. For $N$ samples, the accuracy is $\mathcal{O}(1/\sqrt{N})$. In recent work, we have introduced multigrid multilevel Monte Carlo: having a multigrid hierarchy with operators $D_{\ell }$, $P_{\ell }$ and $R_{\ell }$, for level $\ell$, we can rewrite the trace $\mathrm{tr}(D^{-1})$ via a telescopic sum with difference-levels, written in terms of the aforementioned operators and with a reduced variance. We have seen significant reductions in the variance and the total work with respect to exactly deflated Hutchinson. In this work, we explore the use of exact deflation in combination with the multigrid multilevel Monte Carlo method, and demonstrate how this leads to both algorithmic and computational gains.

   hep-latcs.NAmath.NAPoS(2023)·1 citation
5. 05*

   Status of reproducibility and open science in hep-lat in 2021

   Ed Bennett🇬🇧

   As a fully computational discipline, Lattice Field Theory has the potential to give results that anyone with sufficient computational resources can reproduce, going from input parameters to published numbers and plots correct to the last byte. After briefly motivating and outlining some of the key steps in making lattice computations reproducible, this contribution presents the results of a survey of all 1,229 submissions to the hep-lat arXiv in 2021 of how explicitly reproducible each is. Areas where LFT has historically been well ahead of the curve are highlighted, as are areas where there are opportunities to do more.

   hep-latPoS(2023)·5 citations
6. 06*

   Aspects of chiral symmetry in QCD at T = 128 MeV

   Marco Cè🇨🇭 · Tim Harris🇬🇧 · Ardit Krasniqi🇩🇪 · Harvey B. Meyer🇩🇪 · Csaba Török🇩🇪

   We investigate several aspects of chiral symmetry in QCD at a temperature of $T=128\text{MeV}$. The study is based on a $24\times 96^3$ lattice-QCD ensemble with O($a$)-improved Wilson quarks and physical up, down and strange quark masses. The pion quasiparticle turns out to be significantly lighter than the zero-temperature pion mass, even though the corresponding static correlation length is shorter. We perform a quantitative comparison of our findings to predictions of chiral perturbation theory. Among several order parameters for chiral symmetry restoration, we compute the difference of the vector- and axial-vector time-dependent correlators and find it to be reduced by a factor $\sim 2/3$ as compared to its vacuum counterpart.

   hep-latPRD(2023)·7 citations
7. 07*

   Coordinate-space calculation of the window observable for the hadronic vacuum polarization contribution to $(g-2{)}_{\mu }$

   En-Hung Chao🇺🇸 · Harvey B. Meyer🇩🇪 · Julian Parrino🇩🇪

   The `intermediate window quantity' of the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon allows for a high-precision comparison between the data-driven approach and lattice QCD. The existing lattice results, which presently show good consistency among each other, are in strong tension with the data-driven determination. In order to check for a potentially common source of systematic error of the lattice calculations, which are all based on the time-momentum representation (TMR), we perform a calculation using a Lorentz-covariant coordinate-space (CCS) representation. We present results for the isovector and the connected strange-quark contributions to the intermediate window quantity at a reference point in the $(m_{\pi },m_K)$ plane, in the continuum and infinite-volume limit, based on four different lattice spacings. Our results are in good agreement with those of the recent TMR-based Mainz-CLS publication.

   hep-latPRD(2023)·19 citations
8. 08*

   Gluon helicity distribution in the nucleon from lattice QCD and machine learning

   Tanjib Khan🇧🇩 · Tianbo Liu🇨🇳 · Raza Sabbir Sufian🇺🇸

   We present the first lattice QCD determination of the light cone gluon helicity correlation parton distribution function (PDF) with numerical evidence toward disfavoring negative gluon polarization in the nucleon. We present a solution for eliminating an inevitable contamination term that dominates the Euclidean correlations and makes determining gluon helicity PDF unfeasible. The proposed synergy between lattice QCD and artificial intelligence offers a superior platform to alleviate the defining challenge of extracting quark and gluon PDFs from the lattice data that are available in a limited domain due to a finite range of accessible hadron momenta. We suggest a systematically improvable method to extract PDFs from the lattice data, independent of inadequate parametrizations. The result of the gluon helicity will improve our understanding of the role of spin in the strong interaction and the nucleon spin structure.

   hep-lathep-phnucl-thPRD(2023)·34 citations
9. 09*

   Inclusive semi-leptonic $B_{(s)}$ mesons decay at the physical $b$ quark mass

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

   We address the non-perturbative calculation of the decay rate of inclusive semi-leptonic $B_{(s)}$ mesons decays from lattice QCD. Precise theoretical Standard Model predictions are key ingredients in searches for new physics. This type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the CKM matrix elements $|V_{cb}|$ and $|V_{ub}|$. We perform a pilot lattice computation for $B_s\to X_{c}l{\nu }_l$ and improve on existing techniques. The valence-quark masses in our simulations are approximately physical for the domain-wall strange and charm quarks as well as for the bottom quark, for which we use a relativistic heavy quark effective action. We report on our progress and discuss future plans towards a first study with fully controlled systematic effects.

   hep-latPoS(2023)·16 citations
10. 10*

    Towards learning optimized kernels for complex Langevin

    Daniel Alvestad🇳🇴 · Rasmus Larsen🇳🇴 · Alexander Rothkopf🇳🇴

    We present a novel strategy aimed at restoring correct convergence in complex Langevin simulations. The central idea is to incorporate system-specific prior knowledge into the simulations, in order to circumvent the NP-hard sign problem. In order to do so, we modify complex Langevin using kernels and propose the use of modern auto-differentiation methods to learn optimal kernel values. The optimization process is guided by functionals encoding relevant prior information, such as symmetries or Euclidean correlator data. Our approach recovers correct convergence in the non-interacting theory on the Schwinger-Keldysh contour for any real-time extent. For the strongly coupled quantum anharmonic oscillator we achieve correct convergence up to three-times the real-time extent of the previous benchmark study. An appendix sheds light on the fact that for correct convergence not only the absence of boundary terms, but in addition the correct Fokker-Plank spectrum is crucial.

    hep-latJHEP(2023)·30 citations
11. 11*

    Exploring distillation at the SU(3) flavour symmetric point

    Felix Erben🇬🇧 · Maxwell T. Hansen🇬🇧 · Fabian Joswig🇬🇧 · Nelson Pitanga Lachini🇬🇧 · Antonin Portelli🇬🇧

    In these proceedings we present an exact distillation setup with stabilised Wilson fermions at the SU(3) flavour symmetric point utilising the flexibility of the Grid and Hadrons software libraries. This work is a stepping stone towards a non-perturbative investigation of hadronic D-decays, for which one needs to control the multi-hadron final states. As a first step we study two-to-two s-wave scattering of pseudoscalar mesons. In particular we examine the reliability of the extraction of finite-volume energies as a function of the number of eigenvectors of the gauge-covariant Laplacian entering our distillation setup.

    hep-latPoS(2023)·8 citations
12. 12*

    QCD spectral sum rules 2022

    Stephan Narison🇫🇷

    We present a compact review of the status of QCD spectral sum rules until 2022. We emphasize the recent progresses for determining the QCD input parameters (${\alpha }_s$, running quark masses, quark and gluon condensates) where their correlations have been taken into account. Some selected phenomenological uses of the sum rules in different channels (light and heavy quarks, gluonia/glueballs, hybrids and four-quark states) are briefly reviewed and commented. The estimate of the $1^{-+}$ light hybrid mass is revised which confirms the hybrid nature of the ${\pi }_1(1600)$ but not the ${\pi }_1(2050)$.

    ↳ hep-phhep-exhep-latNucl.Part.Phys.Proc.(2023)·11 citations
13. 13*

    Molecular Interpretation of $X(3960)$ as $D_s^{+}{D}_s^{-}$ State

    Halil Mutuk🇹🇷

    We study $D_s^{+}{D}_s^{-}$ and $D\bar{D}$ states assuming that they are hadronic molecules with $J^{PC}=0^{++}$ quantum number. We use two-point QCD sum rule formalism and extract the mass and decay constant values of these states. We take into account contributions of various quark, gluon, and mixed vacuum condensates up to dimension eight. The extracted mass and decay constant values of $D\bar{D}$ and $D_s^{+}{D}_s^{-}$ states read as $M_{D\bar{D}}=3795_{-82}^{+85}\mathrm{MeV}$, $f_{D\bar{D}}=1.70_{-0.29}^{+0.33}\times 10^{-2}{\mathrm{GeV}}^5$, and $M_{D_s^{+}{D}_s^{-}}=3983_{-88}^{+93}\mathrm{MeV}$, $f_{D_s^{+}{D}_s^{-}}=2.52_{-0.54}^{+0.64}\times 10^{-2}{\mathrm{GeV}}^5$, respectively. The predicted mass of $D_s^{+}{D}_s^{-}$ state is in good agreement with the recent LHCb observation and supports quantum number and molecular picture assignments. A possible observation of $D\bar{D}$ state would help for establishing the lowest four-quark state in charmonium sector.

    ↳ hep-phhep-exhep-latEPJC(2022)·35 citations
14. 14*

    The DM approach to semileptonic heavy-to-heavy and heavy-to-light $B$ decays

    G. Martinelli🇮🇹 · M. Naviglio🇮🇹 · S. Simula🇮🇹 · L. Vittorio🇫🇷

    We present the results of the application of the Dispersion Matrix approach to semileptonic heavy-to-heavy and heavy-to-light $B$-meson decays. This method allows to determine the hadronic form factors in a non-perturbative and model-independent way. Starting from the available lattice results at large values of the momentum transfer, we obtain the behaviour of the form factors in their whole kinematical range without introducing any parameterization of their momentum dependence. We will focus on the determination of the Cabibbo-Kobayashi-Maskawa matrix elements $|V_{cb}|$ and $|V_{ub}|$ through the analysis of $B\to D^{(\ast )}\ell \nu$, $B_s\to D_s^{(\ast )}\ell \nu$, $B\to \pi \ell \nu$ and $B_s\to K\ell \nu$ decays. New theoretical determinations of the Lepton Flavour Universality ratios relevant for these transitions will be also presented, by focusing in particular on the $R(D_{(s)}^{(\ast )})$ ratios.

    ↳ hep-phhep-exhep-latPoS(2023)·2 citations
15. 15*

    From Trees to Gravity

    Bergfinnur Durhuus🇩🇰 · Thordur Jonsson🇮🇸 · John Wheater🇬🇧

    In this article we study two related models of quantum geometry: generic random trees and two-dimensional causal triangulations. The Hausdorff and spectral dimensions that arise in these models are calculated and their relationship with the structure of the underlying random geometry is explored. Modifications due to interactions with matter fields are also briefly discussed. The approach to the subject is that of classical statistical mechanics and most of the tools come from probability and graph theory.

    ↳ hep-thhep-latmath-phmath.MP4 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.