Dark sectors at the Fermilab SeaQuest experiment

101

166

One proposed component of the upcoming Deep Underground Neutrino Experiment (DUNE) near detector complex is a multi-purpose, magnetized, gaseous argon time projection chamber: the Multi-Purpose Detector (MPD). We explore the new-physics potential of the MPD, focusing on scenarios in which the MPD is significantly more sensitive to new physics than a liquid argon detector, specifically searches for semi-long-lived particles that are produced in/near the beam target and decay in the MPD. The specific physics possibilities studied are searches for dark vector bosons mixing kinetically with the Standard Model hypercharge group, leptophilic vector bosons, dark scalars mixing with the Standard Model Higgs boson, and heavy neutral leptons that mix with the Standard Model neutrinos. We demonstrate that the MPD can extend existing bounds in most of these scenarios. We illustrate how the ability of the MPD to measure the momentum and charge of the final state particles leads to these bounds. arXiv:1912.07622v1 [hep-ph] 16 Dec 2019 Liquid Argon Near Detector: The liquid argon near detector has a width (transverse to the beam direction) of 7 m, a height of 3 m, and a length (in the beam direction) of 5 m. The fiducial mass of the near detector is 50 t of argon. See Ref. [2] for more detail.Multi-Purpose Detector: The Multi-Purpose Detector (MPD) is a magnetic spectrometer with a cylindrical high-pressure gaseous argon time projection chamber (HPTPC) at its heart. The HPTPC has a diameter of 5 m and a length of 5 m. It is surrounded by an electromagnetic calorimeter (ECAL) and the HPTPC+ECAL system is situated inside a magnet with 0.5 T central field. The axis of the cylinder is perpendicular to the beam direction. However, for simplicity, when simulating our signals (see Section 3), * Some projections of DUNE operation include the possibility of an upgraded beam (roughly twice the number of protons on target per year) that can operate in the second half of the experiment. We assume a constant number of protons on target per year, so our ten-year projection is equivalent to a shorter operation time with such an upgraded beam. † This is in contrast with the LArTPC, where the conversion distance of photons is O(10 cm). Far more photons can fake the signal of e + e − in the LArTPC than in the HPTPC. * Ref. [63] provides a thorough review of searches for dark photons and existing constraints. * The results of this analysis in antineutrino mode are qualitatively equivalent.

Section: Dark Photon Productionmentioning

confidence: 88%

Searches for decays of new particles in the DUNE Multi-Purpose near Detector

Berryman

Gouvêa

Fox

et al. 2020

101

166

“…figure 7 of Ref. [16] for a comprehensive compendium, including possible add-ons to the LHC such as FASER [41], MATHUSLA [42], and CODEX-b [43] or future beam dumps such as LDMX [44] and SeaQuest [38]. We will consider these projections more closely in section 4.…”

Section: Established Limits and Future Prospectsmentioning

confidence: 99%

Invisible and displaced dark matter signatures at Belle II

Duerr

Ferber

Hearty

et al. 2020

121

Many dark matter models generically predict invisible and displaced signatures at Belle II, but even striking events may be missed by the currently implemented search programme because of inefficient trigger algorithms. Of particular interest are final states with a single photon accompanied by missing energy and a displaced pair of electrons, muons, or hadrons. We argue that a displaced vertex trigger will be essential to achieve optimal sensitivity at Belle II. To illustrate this point, we study a simple but well-motivated model of thermal inelastic dark matter in which this signature naturally occurs and show that otherwise inaccessible regions of parameter space can be tested with such a search. We also evaluate the sensitivity of single-photon searches at BaBar and Belle II to this model and provide detailed calculations of the relic density target.

“…LHCb [65,66], Belle-II [60,67], AWAKE [68] (10 16 electrons of 50 GeV), HPS [69], SeaQuest [70], LDMX [71] (HL-LDMX with E beam = 16 GeV), FASER [72] (LHC Run 3 with 150 fb −1 ), NA62 [73], and SHiP [74]. Additionally, the NA64 bounds should improve soon [75].…”

Section: A Dark Neutron Dark Mattermentioning

confidence: 99%

“…The constraints specific to our models, namely that m γ ≤ m π 0 /2 and that the dark photon decays before SM neutrinos decouple around T ∼ 3 MeV, are in light blue and red, respectively. Also shown in rainbow colors are projections from future experiments [60,[65][66][67][68][69][70][71][72][73][74]. Left: Viable parameter space for the dark neutron dark matter case with the predicted m n = 1.33 GeV and assuming m π ∼ 0.5m n .…”

Section: B Dark Proton and Pion Dark Mattermentioning

confidence: 99%

Baryogenesis from a dark first-order phase transition

Hall

Konstandin

McGehee

et al. 2020

We introduce a model for matters-genesis in which both the baryonic and dark matter asymmetries originate from a first-order phase transition in a dark sector with an SU (3) × SU (2) × U (1) gauge group and minimal matter content. In the simplest scenario, we predict that dark matter is a dark neutron with mass either mn = 1.33 GeV or mn = 1.58 GeV. Alternatively, dark matter may be comprised of equal numbers of dark protons and pions. This model, in either scenario, is highly discoverable through both dark matter direct detection and dark photon search experiments. The strong dark matter self interactions may ameliorate small-scale structure problems, while the strongly first-order phase transition may be confirmed at future gravitational wave observatories.