Searches for dark photons provide serendipitous discovery potential for other types of vector particles. We develop a framework for recasting dark photon searches to obtain constraints on more general theories, which includes a data-driven method for determining hadronic decay rates. We demonstrate our approach by deriving constraints on a vector that couples to the B-L current, a leptophobic B boson that couples directly to baryon number and to leptons via B-γ kinetic mixing, and on a vector that mediates a protophobic force. Our approach can easily be generalized to any massive gauge boson with vector couplings to the Standard Model fermions, and software to perform any such recasting is provided at https://gitlab.com/philten/darkcast.

We present a new method to characterize unresolved point sources (PSs) generalizing traditional template fits to account for non-Poissonian photon statistics. We apply this method to Fermi Large Area Telescope γ-ray data to characterize PS populations at high latitudes and in the Inner Galaxy. We find that PSs (resolved and unresolved) account for ∼50% of the total extragalactic γ-ray background in the energy range ∼1.9 to 11.9 GeV. Within 10°of the Galactic Center with jbj ≥ 2°, we find that ∼5%-10% of the flux can be accounted for by a population of unresolved PSs distributed consistently with the observed ∼GeV γ-ray excess in this region. The excess is fully absorbed by such a population, in preference to dark-matter annihilation. The inferred source population is dominated by near-threshold sources, which may be detectable in future searches.

Femtolensing of gamma ray bursts (GRBs) has been put forward as an exciting possibility to probe exotic astrophysical objects with masses below 10−13 solar masses such as small primordial black holes or ultra-compact dark matter minihalos, made up for instance of QCD axions. In this paper we critically review this idea, properly taking into account the extended nature of the source as well as wave optics effects. We demonstrate that most GRBs are inappropriate for femtolensing searches due to their large sizes. This removes the previous femtolensing bounds on primordial black holes, implying that vast regions of parameter space for primordial black hole dark matter are not robustly constrained. Still, we entertain the possibility that a small fraction of GRBs, characterized by fast variability can have smaller sizes and be useful. However, a large number of such bursts would need to be observed to achieve meaningful constraints. We study the sensitivity of future observations as a function of the number of detected GRBs and of the size of the emission region.

We propose an inclusive search for dark photons A 0 at the LHCb experiment based on both prompt and displaced dimuon resonances. Because the couplings of the dark photon are inherited from the photon via kinetic mixing, the dark photon A 0 → μ þ μ − rate can be directly inferred from the off-shell photon γ Ã → μ þ μ − rate, making this a fully data-driven search. For run 3 of the LHC, we estimate that LHCb will have sensitivity to large regions of the unexplored dark-photon parameter space, especially in the 210-520 MeV and 10-40 GeV mass ranges. This search leverages the excellent invariant-mass and vertex resolution of LHCb, along with its unique particle-identification and real-time data-analysis capabilities. DOI: 10.1103/PhysRevLett.116.251803 Dark matter-firmly established through its interactions with gravity-remains an enigma. Though there are increasingly stringent constraints on direct couplings between visible matter and dark matter, little is known about the dynamics within the dark sector itself. An intriguing possibility is that dark matter might interact via a new dark force, felt only feebly by standard model (SM) particles. This has motivated a worldwide effort to search for dark forces and other portals between the visible and dark sectors (see Ref.[1] for a review).A particularly compelling dark-force scenario is that of a dark photon A 0 which has small SM couplings via kinetic mixing with the ordinary photon through the operator ðϵ=2ÞF 0 μν F μν [2][3][4][5][6][7]. Previous beam dump [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], fixed target [22][23][24], collider [25][26][27], and rare meson decay [28][29][30][31][32][33][34][35][36][37] experiments have already played a crucial role in constraining the dark photon mass m A 0 and kinetic-mixing strength ϵ 2 . Large regions of the m A 0 − ϵ 2 plane, however, are still unexplored (see Fig. 1). Looking to the future, a wide variety of innovative experiments have been proposed to further probe the dark photon parameter space [38][39][40][41][42][43][44][45][46][47][48], though new ideas are needed to test m A 0 > 2m μ and ϵ 2 ∈ ½10 −7 ; 10 −11 .In this Letter, we propose a search for dark photons via the decayat the LHCb experiment during LHC run 3 (scheduled for 2021-2023). The potential of LHCb to discover dark photons was recently emphasized in Ref.[48], which exploits the exclusive charm decay modeHere, we consider an inclusive approach where the production mode of A 0 need not be specified. An important feature of this search is that it can be made fully data driven, since the A 0 signal rate can be inferred from measurements of the SM prompt μ þ μ − spectrum. The excellent invariant-mass and vertex resolution of the LHCb detector, along with its unique particle-identification and real-time data-analysis capabilities [50,51], make it highly sensitive to A 0 → μ þ μ − . We derive the LHCb sensitivity for both prompt and displaced A 0 decays, and show that LHCb can probe otherwise inaccessible regions of the m A 0 − ϵ 2 plane...

We present a simplified version of the atomic dark matter scenario, in which charged dark constituents are bound into atoms analogous to hydrogen by a massless hidden sector U(1) gauge interaction. Previous studies have assumed that interactions between the dark sector and the standard model are mediated by a second, massive Z ′ gauge boson, but here we consider the case where only a massless γ ′ kinetically mixes with the standard model hypercharge and thereby mediates direct detection. This is therefore the simplest atomic dark matter model that has direct interactions with the standard model, arising from the small electric charge for the dark constituents induced by the kinetic mixing. We map out the parameter space that is consistent with cosmological constraints and direct searches, assuming that some unspecified mechanism creates the asymmetry that gives the right abundance, since the dark matter cannot be a thermal relic in this scenario. In the special case where the dark "electron" and "proton" are degenerate in mass, inelastic hyperfine transitions can explain the CoGeNT excess events. In the more general case, elastic transitions dominate, and can be close to current direct detection limits over a wide range of masses.