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SUMMARY:Combined constraints on dark photons from high-energy collisions\,
  cosmology\, and astrophysics
DTSTART:20260528T080000Z
DTEND:20260528T100000Z
DTSTAMP:20260523T055700Z
UID:indico-event-1452@indico.hiskp.uni-bonn.de
DESCRIPTION:Speakers: Adrian Romero Jorge (Goethe University Frankfurt)\n\
 nAbstract: \nWe investigate a dark sector coupled to the Standard Model (
 SM) through a kinetically mixed dark photon $U$ associated with a new $U(1
 )'$ gauge symmetry. Kinetic mixing\, parametrized by $\\varepsilon$\, indu
 ces an effective coupling to the electromagnetic current\, while the dark 
 photon interacts with a stable dark matter (DM) particle $\\chi$ through a
  dark gauge coupling $g_\\chi$\,  defining a four-dimensional parameter s
 pace $(m_U\,\\varepsilon\,m_\\chi\,g_\\ chi)$. Our analysis is based on th
 e parton-hadron-string dynamics (PHSD) transport approach\, extended to in
 clude dark photon production and decay into dileptons ($U\\!\\to e^+e^-$).
  In PHSD\, dark photons are produced in high-energy collisions through Dal
 itz decays of light mesons ($\\pi^0\,\\eta\,\\eta'\,\\omega$)\, Delta-reso
 nances ($\\Delta\\!\\to N U$)\, direct vector meson decays ($\\rho\,\\omeg
 a\,\\phi\\!\\to U$)\, kaon decays ($K^+\\!\\to\\pi^+U$)\, and $q\\bar q\\!
 \\to U$ annihilation. Building on previous PHSD benchmarks against dilepto
 n data\, we extract upper limits on $\\varepsilon^2(m_U\,m_\\chi\,\\ alpha
 _\\chi)$ in both the visible regime ($m_U<2m_\\chi$)\, where $U\\!\\to e^+
 e^-$ dominates\, and the invisible regime ($m_U>2m_\\chi$)\, where $U\\!\\
 to\\chi\\bar\\chi$ is kinematically open and suppresses the dilepton branc
 hing fraction. Cosmological and astrophysical constraints are incorporated
  in two complementary ways. First\, we compute the velocity-dependent self
 -interaction cross section $\\sigma/m_\\chi$ for Yukawa-mediated SIDM and 
 confront it with bounds from dwarf galaxies\, galaxy groups\, and clusters
 . Second\, we determine thermal relic target curves by computing the relic
  abundance and requiring $\\Omega_{\\rm DM}h^2\\simeq 0.12$\, consistent w
 ith Planck measurements of the cosmic microwave background. Combining PHSD
  limits on $\\varepsilon^2$ with relic density and self-interaction requir
 ements\, we exclude regions of the $(m_\\chi\,m_U)$ plane for each DM real
 ization (Dirac fermion\, Majorana fermion\, or complex scalar) and identif
 y benchmark scenarios in which heavy-ion\, cosmological\, and astrophysica
 l constraints are simultaneously satisfied.\n \nJoin Zoom Meetinghttps://
 uni-bonn.zoom-x.de/j/66253567797?pwd=R2MrNmNCQnl4K1hSejd6VnBEYXJ2QT09\nMee
 ting ID: 662 5356 7797Passcode: 599591\n\nhttps://indico.hiskp.uni-bonn.de
 /event/1452/
LOCATION:Kreuzbergweg 24/0.052 (FTD) - Präsentationsraum (FTD)
URL:https://indico.hiskp.uni-bonn.de/event/1452/
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