Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs
Abstract Azimuthal modulations in lepton and heavy-quark pair production in ultraperipheral collisions (UPCs) of highly charged ions are investigated. The modulations in the azimuthal angles of the sum and difference of the transverse momenta of the pair of particles in the final state, as well as o...
Saved in:
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2025-01-01
|
| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1007/JHEP01(2025)076 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832595022670725120 |
|---|---|
| author | Daniël Boer Luca Maxia Cristian Pisano |
| author_facet | Daniël Boer Luca Maxia Cristian Pisano |
| author_sort | Daniël Boer |
| collection | DOAJ |
| description | Abstract Azimuthal modulations in lepton and heavy-quark pair production in ultraperipheral collisions (UPCs) of highly charged ions are investigated. The modulations in the azimuthal angles of the sum and difference of the transverse momenta of the pair of particles in the final state, as well as of the transverse impact parameter, arise from the collisions of unpolarized and polarized photons. A full description of the cross section in terms of Generalized Transverse Momentum Dependent parton distributions (GTMDs) for photons is given including a careful consideration of the Fourier transform to impact parameter space. In particular, this leads to a feed-in mechanism among harmonics of different orders, which in principle generates harmonics of all (even) orders. Wherever comparable, our analytical results for the azimuthal modulations agree with those presented in other papers on this topic. Compared to these other works, we separate effects that arise from the anisotropies of the GTMDs from those that do not and retain terms proportional to the mass of the produced particles, as they are relevant for muon, charm and bottom quark production. We show that the normalized differential cross section changes considerably with the produced particle mass, which should be discernible in UPCs at RHIC and LHC. For the numerical results we adopt several models for the photon GTMD correlator, and find that all of them are in fairly good agreement with each other and with UPC data from STAR. We also present results for various azimuthal modulations for RHIC kinematics, where we compare e + e − production with the production of heavier particles, and for LHC kinematics, focusing on μ + μ − production. These results exhibit interesting mass-dependent features in the asymmetries that may help study the anisotropies arising from the underlying photon GTMD description. |
| format | Article |
| id | doaj-art-0c28ecaf61c14a1dbe552fdff01f3bbb |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-0c28ecaf61c14a1dbe552fdff01f3bbb2025-01-19T12:07:45ZengSpringerOpenJournal of High Energy Physics1029-84792025-01-012025113210.1007/JHEP01(2025)076Azimuthal asymmetries in lepton and heavy-quark pair production in UPCsDaniël Boer0Luca Maxia1Cristian Pisano2Van Swinderen Institute for Particle Physics and Gravity, University of GroningenVan Swinderen Institute for Particle Physics and Gravity, University of GroningenDipartimento di Fisica, Università di Cagliari, Cittadella UniversitariaAbstract Azimuthal modulations in lepton and heavy-quark pair production in ultraperipheral collisions (UPCs) of highly charged ions are investigated. The modulations in the azimuthal angles of the sum and difference of the transverse momenta of the pair of particles in the final state, as well as of the transverse impact parameter, arise from the collisions of unpolarized and polarized photons. A full description of the cross section in terms of Generalized Transverse Momentum Dependent parton distributions (GTMDs) for photons is given including a careful consideration of the Fourier transform to impact parameter space. In particular, this leads to a feed-in mechanism among harmonics of different orders, which in principle generates harmonics of all (even) orders. Wherever comparable, our analytical results for the azimuthal modulations agree with those presented in other papers on this topic. Compared to these other works, we separate effects that arise from the anisotropies of the GTMDs from those that do not and retain terms proportional to the mass of the produced particles, as they are relevant for muon, charm and bottom quark production. We show that the normalized differential cross section changes considerably with the produced particle mass, which should be discernible in UPCs at RHIC and LHC. For the numerical results we adopt several models for the photon GTMD correlator, and find that all of them are in fairly good agreement with each other and with UPC data from STAR. We also present results for various azimuthal modulations for RHIC kinematics, where we compare e + e − production with the production of heavier particles, and for LHC kinematics, focusing on μ + μ − production. These results exhibit interesting mass-dependent features in the asymmetries that may help study the anisotropies arising from the underlying photon GTMD description.https://doi.org/10.1007/JHEP01(2025)076Precision QEDProperties of Hadrons |
| spellingShingle | Daniël Boer Luca Maxia Cristian Pisano Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs Journal of High Energy Physics Precision QED Properties of Hadrons |
| title | Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs |
| title_full | Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs |
| title_fullStr | Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs |
| title_full_unstemmed | Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs |
| title_short | Azimuthal asymmetries in lepton and heavy-quark pair production in UPCs |
| title_sort | azimuthal asymmetries in lepton and heavy quark pair production in upcs |
| topic | Precision QED Properties of Hadrons |
| url | https://doi.org/10.1007/JHEP01(2025)076 |
| work_keys_str_mv | AT danielboer azimuthalasymmetriesinleptonandheavyquarkpairproductioninupcs AT lucamaxia azimuthalasymmetriesinleptonandheavyquarkpairproductioninupcs AT cristianpisano azimuthalasymmetriesinleptonandheavyquarkpairproductioninupcs |