Prospects on searches for baryonic Dark Matter produced in $${\varvec{b}}$$-hadron decays at LHCb

Abstract

A model that can simultaneously explain Dark Matter relic density and the apparent matter anti-matter imbalance of the universe has been recently proposed. The model requires b-hadron branching fractions to Dark Matter at the per mille level. The b-hadrons decay to a dark sector baryon, $$\psi _{\mathrm{DS}}$$ ψ DS , which has a mass in the region $$940 ~\mathrm{MeV}/c^2\le m_{\psi _{\mathrm{DS}}}\le 4430~\mathrm{MeV}/c^2$$ 940 MeV / c 2 ≤ m ψ DS ≤ 4430 MeV / c 2 . In this paper, we discuss the sensitivity of the LHCb experiment to search for this dark baryon, covering different types of topology and giving prospects for Runs 3 and 4 of the LHC, as well as for the proposed Upgrade II. We show that the LHCb experiment can cover the entire mass range of the hypothetical dark baryon.

New Physics Searches at Kaon and Hyperon Factories

“…For y ξφ = 1, which would maintain the ξ and φ populations in thermal equilibrium until the temperature of the early Universe is T = 2 MeV, this would induce a decay rate for Λ → ξ + φ at the level of 10 −6 , which should be compared with the recent constraint from BESIII [280], B(Λ → invisible) < 7 × 10 −5 at 90% CL. These examples thus demonstrate that searches at BESIII could represent a relevant test of B-Mesogenesis in a way that is complementary to the LHC searches for resonant jets and missing energy at TeV energies, and direct searches to dark decays of b-flavored hadrons [292,293].…”

“…The experimental sensitivity of hyperon decays to dark baryons predicted by Bmesogenesis (Section 2.9) has been evaluated for this paper, using the same fast simulation and methodology as done for B decays in Ref. [293]. We conclude that the expected sensitivities are at the 10 −6 level for B(Ξ 0 → π + π − ψ DS ), and O(10 −10 ) for B(Ξ − → µ + µ − π − ψ DS ), where ψ DS is a dark sector particle escaping detection.…”

The Strange Physics of Dark Baryons

“…This implies that in order to target these decays, one would need several particles in the final state to have a handle on missing energy. Experimentally, this approach has been studied in [46] to target b-hadron decays with large missing energy, showcasing very good sensitivities in these systems. From the theoretical perspective, we expect decays involving many pions in the final state to be possible only in Ξ 0 decays and only in a very small region of the parameter space.…”

“…For example, studies of the neutron lifetime anomaly have broadly showcased that the neutron may have a branching ratio to dark sector states as large as 1% [25], whereas studies of the B-Mesogenesis paradigm [32] highlighted that B mesons can have a branching ratio as large as 0.5% to GeV-scale dark sector baryons (in stark contrast to other modes, such as B s → µ + µ − , see, e.g., [39], for which sensitivities at the level 10 −9 have been reached). These theoretical developments have triggered dedicated searches for new neutron decay channels such as n → χγ [40], n → χ e + e − [41] and nuclear dark decays [42,43], as well as searches for the decays of non-standard b-flavored hadrons at experiments like BaBar, Belle and Belle-II [44], and LHCb [45,46].…”

Unleashing the full power of LHCb to probe Stealth New Physics

“…• One can search for processes such as B + → ψ + B , where B is an excited baryon that decays promptly [189]. B would be easier to tag as the decay track will not be displaced.…”