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Two-loop form factors for pseudo-scalar quarkonium production and decay
We present the analytic expressions for the two-loop form factors for the production or decay of pseudo-scalar quarkonia, in a scheme where the quarks are produced at threshold. We consider the two-loop amplitude for the process $ \gamma \gamma \leftrightarrow {}^1{S}_0^{\left[1\right]} $, that was...
Autores principales: | , , , |
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Lenguaje: | eng |
Publicado: |
2022
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Acceso en línea: | https://dx.doi.org/10.1007/JHEP02(2023)250 http://cds.cern.ch/record/2841206 |
_version_ | 1780976170839310336 |
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author | Abreu, Samuel Becchetti, Matteo Duhr, Claude Ozcelik, Melih A. |
author_facet | Abreu, Samuel Becchetti, Matteo Duhr, Claude Ozcelik, Melih A. |
author_sort | Abreu, Samuel |
collection | CERN |
description | We present the analytic expressions for the two-loop form factors for the production or decay of pseudo-scalar quarkonia, in a scheme where the quarks are produced at threshold. We consider the two-loop amplitude for the process $ \gamma \gamma \leftrightarrow {}^1{S}_0^{\left[1\right]} $, that was previously known only numerically, as well as for the processes $ gg\leftrightarrow {}^1{S}_0^{\left[1\right]} $, $ \gamma g\leftrightarrow {}^1{S}_0^{\left[8\right]} $ and $ gg\leftrightarrow {}^1{S}_0^{\left[8\right]} $, which have not been computed before. The two-loop corrections to $ gg\leftrightarrow {}^1{S}_0^{\left[1\right]} $ are the last missing ingredients for a full NNLO calculation of η$_{Q}$ hadro-production. We discuss how the singularity structure of the amplitudes is affected by the threshold kinematics, which in particular introduces Coulomb singularities. In this context, we first show how the usual structure of the infrared singularities degenerates at threshold kinematics, and then extract the anomalous dimensions governing the Coulomb singularities for colour-singlet and octet channels, the latter being presented here for the first time. We give high-precision numerical results for the hard functions, which can be used for phenomenological studies of η$_{Q}$ production and decay at NNLO. |
id | cern-2841206 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2022 |
record_format | invenio |
spelling | cern-28412062023-10-04T06:48:33Zdoi:10.1007/JHEP02(2023)250http://cds.cern.ch/record/2841206engAbreu, SamuelBecchetti, MatteoDuhr, ClaudeOzcelik, Melih A.Two-loop form factors for pseudo-scalar quarkonium production and decaynucl-thNuclear Physics - Theoryhep-phParticle Physics - PhenomenologyWe present the analytic expressions for the two-loop form factors for the production or decay of pseudo-scalar quarkonia, in a scheme where the quarks are produced at threshold. We consider the two-loop amplitude for the process $ \gamma \gamma \leftrightarrow {}^1{S}_0^{\left[1\right]} $, that was previously known only numerically, as well as for the processes $ gg\leftrightarrow {}^1{S}_0^{\left[1\right]} $, $ \gamma g\leftrightarrow {}^1{S}_0^{\left[8\right]} $ and $ gg\leftrightarrow {}^1{S}_0^{\left[8\right]} $, which have not been computed before. The two-loop corrections to $ gg\leftrightarrow {}^1{S}_0^{\left[1\right]} $ are the last missing ingredients for a full NNLO calculation of η$_{Q}$ hadro-production. We discuss how the singularity structure of the amplitudes is affected by the threshold kinematics, which in particular introduces Coulomb singularities. In this context, we first show how the usual structure of the infrared singularities degenerates at threshold kinematics, and then extract the anomalous dimensions governing the Coulomb singularities for colour-singlet and octet channels, the latter being presented here for the first time. We give high-precision numerical results for the hard functions, which can be used for phenomenological studies of η$_{Q}$ production and decay at NNLO.We present the analytic expressions for the two-loop form factors for the production or decay of pseudo-scalar quarkonia, in a scheme where the quarks are produced at threshold. We consider the two-loop amplitude for the process $\gamma \gamma \leftrightarrow {^1S_0^{[1]}}$, that was previously known only numerically, as well as for the processes $gg \leftrightarrow {^1S_0^{[1]}}$, $\gamma g \leftrightarrow {^1S_0^{[8]}}$ and $gg \leftrightarrow {^1S_0^{[8]}}$, which have not been computed before. The two-loop corrections to $gg \leftrightarrow {^1S_0^{[1]}}$ are the last missing ingredients for a full NNLO calculation of $\eta_Q$ hadro-production. We discuss how the singularity structure of the amplitudes is affected by the threshold kinematics, which in particular introduces Coulomb singularities. In this context, we first show how the usual structure of the infrared singularities degenerates at threshold kinematics, and then extract the anomalous dimensions governing the Coulomb singularities for colour-singlet and octet channels, the latter being presented here for the first time. We give high-precision numerical results for the hard functions, which can be used for phenomenological studies of $\eta_Q$ production and decay at NNLO.arXiv:2211.08838BONN-TH-2022-23CERN-TH-2022-187TTP22-068oai:cds.cern.ch:28412062022-11-16 |
spellingShingle | nucl-th Nuclear Physics - Theory hep-ph Particle Physics - Phenomenology Abreu, Samuel Becchetti, Matteo Duhr, Claude Ozcelik, Melih A. Two-loop form factors for pseudo-scalar quarkonium production and decay |
title | Two-loop form factors for pseudo-scalar quarkonium production and decay |
title_full | Two-loop form factors for pseudo-scalar quarkonium production and decay |
title_fullStr | Two-loop form factors for pseudo-scalar quarkonium production and decay |
title_full_unstemmed | Two-loop form factors for pseudo-scalar quarkonium production and decay |
title_short | Two-loop form factors for pseudo-scalar quarkonium production and decay |
title_sort | two-loop form factors for pseudo-scalar quarkonium production and decay |
topic | nucl-th Nuclear Physics - Theory hep-ph Particle Physics - Phenomenology |
url | https://dx.doi.org/10.1007/JHEP02(2023)250 http://cds.cern.ch/record/2841206 |
work_keys_str_mv | AT abreusamuel twoloopformfactorsforpseudoscalarquarkoniumproductionanddecay AT becchettimatteo twoloopformfactorsforpseudoscalarquarkoniumproductionanddecay AT duhrclaude twoloopformfactorsforpseudoscalarquarkoniumproductionanddecay AT ozcelikmeliha twoloopformfactorsforpseudoscalarquarkoniumproductionanddecay |