Journal Article

GSI-2021-01318

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Constraints on the kinetic mixing parameter ε$^2$ for the light dark photons from dilepton production in heavy-ion collisions in the few-GeV energy range

Schmidt, I. ; Bratkovskaya, E. (Corresponding author)GSI* ; Gumberidze, M.GSI* ; Holzmann, R.GSI*

2021
Inst. Melville, NY

This record in other databases:

Please use a persistent id in citations: doi:10.1103/PhysRevD.104.015008  doi:10.15120/GSI-2021-01318

Report No.: 2105.00569

Abstract: The vector $U$-bosons, or so called 'dark photons', are one of the possible candidates for the dark matter mediators. They are supposed to interact with the standard matter via a 'vector portal' due to the $U(1)-U(1)^\prime$ symmetry group mixing which might make them visible in particle and heavy-ion experiments. While there is no confirmed observation of dark photons, the detailed analysis of different experimental data allows to estimate the upper limit for the kinetic mixing parameter $\epsilon^2$ depending on the mass $M_U$ of $U$-bosons which is also unknown. In this study we present theoretical constraints on the upper limit of $\epsilon^2(M_U)$ in the mass range $M_U \le 0.6$ GeV from the comparison of the calculated dilepton spectra with the experimental data from the HADES Collaboration at SIS18 energies where the dark photons are not observed. Our analysis is based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach which reproduces well the measured dilepton spectra in $p+p$, $p+A$ and $A+A$ collisions. Additionally to the different dilepton channels originating from interactions and decays of ordinary matter particles (mesons and baryons), we incorporate the decay of hypothetical $U$-bosons to dileptons, $U\to e^+e^-$, where the $U$-bosons themselves are produced by the Dalitz decay of pions $\pi^0\to \gamma U$, $\eta$-mesons $\eta \to \gamma U$ and Delta resonances $\Delta \to N U$. Our analysis can help to estimate the requested accuracy for future experimental searches of 'light' dark photons by dilepton experiments.

Note: Published by the American Physical Society under the terms of the 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.

---

Contributing Institute(s):

1. Heiße & Dichte QCD Materie (TES)
2. HADES (HAD)
3. Helmholtz ForschAkad Hess. f. FAIR, HFHF (FHF)

Research Program(s):

1. 612 - Cosmic Matter in the Laboratory (POF4-612) (POF4-612)
2. SUC-GSI-Frankfurt - Strategic university cooperation GSI-U Frankfurt/M (SUC-GSI-FR) (SUC-GSI-FR)
3. Physics of hot and dense matter - Theory (HFHF project) (I:(DE-Ds200)HFHF-HI-Th) (I:(DE-Ds200)HFHF-HI-Th)

Experiment(s):

1. no experiment theory work (theory)

Appears in the scientific report 2021

---

Database coverage:
; ; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

---