TY - JOUR

T1 - Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD

AU - Giusti, Davide

AU - Kane, Christopher F.

AU - Lehner, Christoph

AU - Meinel, Stefan

AU - Soni, Amarjit

N1 - Funding Information:
S. M. thanks Diego Guadagnoli for asking the question whether the form factors describing radiative-leptonic decays are calculable on the lattice. We thank the RBC and UKQCD Collaborations for providing the gauge-field configurations. C. F. K. is supported by the Department of Energy (DOE) Computational Science Graduate Fellowship under Grant No. DE-SC0020347. S. M. is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Grant No. DE-SC0009913. A. S. is supported in part by the U.S. DOE Contract No. DE-SC0012704. This research used resources provided by the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and the Extreme Science and Engineering Discovery Environment (XSEDE) , which was supported by National Science Foundation Grant No. ACI-1548562. We acknowledge Partnership for Advanced Computing in Europe for awarding us access to SuperMUC-NG at GCS@LRZ, Germany.
Publisher Copyright:
© 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.

PY - 2023/4/1

Y1 - 2023/4/1

N2 - We present a study of lattice-QCD methods to determine the relevant hadronic form factors for radiative-leptonic decays of pseudoscalar mesons. We provide numerical results for Ds+→ℓ+νγ. Our calculation is performed using a domain-wall action for all quark flavors and on a single RBC/UKQCD lattice gauge-field ensemble. The first part of the study is how to best control two sources of systematic error inherent in the calculation, specifically the unwanted excited states created by the meson interpolating field and unwanted exponentials in the sum over intermediate states. Using a 3D sequential propagator allows for better control over unwanted exponentials from intermediate states, while using a 4D sequential propagator allows for better control over excited states. We perform individual analyses of the 3D and 4D methods, as well as a combined analysis using both methods, and find that the 3D sequential propagator offers good control over both sources of systematic uncertainties for the smallest number of propagator solves. From there, we further improve the use of a 3D sequential propagator by employing an infinite-volume approximation method, which allows us to calculate the relevant form factors over the entire allowed range of photon energies. We then study improvements gained by performing the calculation using a different three-point function, using ratios of three-point functions, averaging over positive and negative photon momentum, and using an improved method for extracting the structure-dependent part of the axial form factor. The optimal combination of methods yields results for the Ds+→ℓ+νγ structure-dependent vector and axial form factors in the entire kinematic range with statistical plus fitting uncertainties of order 5%, using 25 gauge configurations with 64 samples per configuration.

AB - We present a study of lattice-QCD methods to determine the relevant hadronic form factors for radiative-leptonic decays of pseudoscalar mesons. We provide numerical results for Ds+→ℓ+νγ. Our calculation is performed using a domain-wall action for all quark flavors and on a single RBC/UKQCD lattice gauge-field ensemble. The first part of the study is how to best control two sources of systematic error inherent in the calculation, specifically the unwanted excited states created by the meson interpolating field and unwanted exponentials in the sum over intermediate states. Using a 3D sequential propagator allows for better control over unwanted exponentials from intermediate states, while using a 4D sequential propagator allows for better control over excited states. We perform individual analyses of the 3D and 4D methods, as well as a combined analysis using both methods, and find that the 3D sequential propagator offers good control over both sources of systematic uncertainties for the smallest number of propagator solves. From there, we further improve the use of a 3D sequential propagator by employing an infinite-volume approximation method, which allows us to calculate the relevant form factors over the entire allowed range of photon energies. We then study improvements gained by performing the calculation using a different three-point function, using ratios of three-point functions, averaging over positive and negative photon momentum, and using an improved method for extracting the structure-dependent part of the axial form factor. The optimal combination of methods yields results for the Ds+→ℓ+νγ structure-dependent vector and axial form factors in the entire kinematic range with statistical plus fitting uncertainties of order 5%, using 25 gauge configurations with 64 samples per configuration.

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U2 - 10.1103/PhysRevD.107.074507

DO - 10.1103/PhysRevD.107.074507

M3 - Article

AN - SCOPUS:85160325594

SN - 2470-0010

VL - 107

JO - Physical Review D

JF - Physical Review D

IS - 7

M1 - 074507

ER -