Revision 2

Accepted · core change · record

Changes against revision 1:

Title: Does a dark photon exist with MeV to GeV mass?
Plain: A dark photon would be a heavy cousin of the photon that mixes slightly with ordinary light. It would appear as a narrow bump in electron-positron pair masses or as missing energy.
Precise · changed · core: Revision 1: Determine whether a $U(1)'$ gauge boson A' with mass 1 MeV to 10 GeV and kinetic mixing $\epsilon \sim 1e-6\ \text{to}\ 1e-3$ exists, in visible ($A' \to \ell+ \ell-$) or invisible decay modes. An answer is a resonance detection or exclusion of the remaining parameter space down to $\epsilon \sim 1e-6\ \text{to}\ 1e-5$.; Revision 2: Determine whether a $U(1)'$ gauge boson $A'$ with mass $1\,\mathrm{MeV}$ to $10\,\mathrm{GeV}$ and kinetic mixing $\epsilon \sim 10^{-6}\ \text{to}\ 10^{-3}$ exists, in visible ($A' \to \ell+ \ell-$) or invisible decay modes. An answer is a resonance detection or exclusion of the remaining parameter space down to $\epsilon \sim 10^{-6}\ \text{to}\ 10^{-5}$.
Settled by: Bump hunts and displaced-vertex searches at LHCb, Belle II, HPS, NA64 and future beam dumps (SHiP).
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 1986

Decisions