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)' 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 ε2 depending on the mass MU of U bosons which is also unknown. In this study we present theoretical constraints on the upper limit of ε2 (MU) in the mass range MU ≤ 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 → e+e−, where the U bosons themselves are produced by the Dalitz decay of pions π0 → γU, η mesons η → γU and Delta resonances Δ → NU. Our analysis can help to estimate the requested accuracy for future experimental searches of "light" dark photons by dilepton experiments.
Search for dark photons in heavy‐ion collisions Bratkovskaya, Elena; Schmidt, Ida; Gumberidze, Malgorzata ...
Astronomische Nachrichten,
January-February 2023, 2023-01-00, 20230101, Volume:
344, Issue:
1-2
Journal Article
Peer reviewed
Open access
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)′$$ U(1)-U{(1)}^{\prime } $$ 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 us to estimate the upper limit for the kinetic mixing parameter ϵ2$$ {\epsilon}^2 $$ depending on the mass MU$$ {M}_U $$ of U‐bosons which is also unknown. We have introduced a procedure to define theoretical constraints on the upper limit of ϵ2MU$$ {\epsilon}^2\left({M}_U\right) $$ from heavy‐ion (as well as p + p and p+A$$ p+A $$) dilepton data. Our analysis is based on the microscopic Parton‐Hadron‐String Dynamics transport approach where we incorporated the decay of hypothetical U‐bosons to dileptons, U→e+e−$$ U\to {e}^{+}{e}^{-} $$, where the U‐bosons themselves are produced by the Dalitz decay of pions π0→γU$$ {\pi}^0\to \gamma U $$, η‐mesons η→γU$$ \eta \to \gamma U $$, and Delta resonances Δ→NU$$ \Delta \to NU $$. The extension of our procedure to other dark matter candidates is foreseen.
It has been demonstrated that Statistical Hadronization Model fits perfectly to particle yields at freeze-out in heavy-ion and hadron collisions at LHC, RHIC and SPS, where quark-gluon plasma is ...created. It is however entirely not clear if particles emitted in the few-GeV energy regime can be understood as emerging from thermalized hadronic medium. Our recent work suggests that this might be the case. By implementing appropriate fireball geometry and expansion pattern in the THERMINATOR (THERMal heavy IoN generATOR) it was possible to describe not only yields, but also the spectra of most abundant particles measured at GSI SIS18. Most of the latter are pure prediction of the model. We present details of the model and extended comparison with experimental data and discuss further developments.
Phys. Rev. D 104, 015008 (2021) 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.
Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in collisions of heavy ...ions, mostly at the Large Hadron Collider, are summarized. A few concrete selected cases are reviewed including searches for axion-like particles, anomalous \(\tau\) electromagnetic moments, magnetic monopoles, and dark photons. Expectations for the achievable sensitivities of these searches in the coming years are given. Studies of CP violation in hot and dense QCD matter and connections to ultrahigh-energy cosmic rays physics are also mentioned.
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