Light neutralino dark matter: direct/indirect detection and collider searches

Abstract

We study the neutralino being the Lightest Supersymmetric Particle (LSP) as a cold Dark Matter (DM) candidate with a mass less than 40 GeV in the framework of the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM). We find that with the current collider constraints from LEP, the Tevatron and the LHC, there are three types of light DM solutions consistent with the direct/indirect searches as well as the relic abundance considerations: (i) A 1 , H 1 -funnels, (ii) stau coannihilation and (iii) sbottom coannihilation. Type-(i) may take place in any theory with a light scalar (or pseudo-scalar) near the LSP pair threshold; while Type-(ii) and (iii) could occur in the framework of Minimal-Supersymmetric-Standard-Model (MSSM) as well. We present a comprehensive study on the properties of these solutions and point out their immediate relevance to the experiments of the underground direct detection such as superCDMS and LUX/LZ, and the astro-physical indirect search such as Fermi-LAT. We also find that the decays of the SM-like Higgs boson may be modified appreciably and the new decay channels to the light SUSY particles may be sizable. The new light CP-even and CP-odd Higgs bosons will decay to a pair of LSPs as well as other observable final states, leading to interesting new Higgs phenomenology at colliders. For the light sfermion searches, the signals would be very challenging to observe at the LHC given the current bounds. However, a high energy and high luminosity lepton collider, such as the ILC, would be able to fully cover these scenarios by searching for events with large missing energy plus charged tracks or displaced vertices.

Testing the light dark matter scenario of the MSSM at the LHC

“…In this case, the chargino mass limits from the LEP experiments have required the DM to be bino-dominated. Then the weak interaction of the DM together with its sizable mass splittings from the other sparticles typically lead to the overproduction of the DM in the early universe, unless that an efficient annihilation mechanism was at work [41,43]. This situation in turn imposes non-trivial requirements on the sparticle spectrum, which serve as an important supplement to the direct search for SUSY at colliders.…”

“…This situation in turn imposes non-trivial requirements on the sparticle spectrum, which serve as an important supplement to the direct search for SUSY at colliders. As a result, only a small corner in the MSSM parameter space is pertinent to the scenario, which makes some signals of the sparticles at the LHC quite distinctive [41,43]. So requiring mχ0 1 100 GeV is not only of theoretical interest, but also can simplify greatly our analysis to get somewhat definite conclusions.…”

“…Recent discussions on the light DM scenario concentrated on the complement of new experimental constraints, such as those from the 125 GeV Higgs data and the direct searches for sparticles at the LHC, and consequently the allowed parameter space of the scenario shrinks significantly [34][35][36][37][38][39][40][41]43]. For example, it was found that the lower bound of mχ0 1 could be improved from about 10 GeV to roughly 25 GeV after considering the searches for multi-τ plus large E miss T signal at the early stage of the LHC Run-I [34].…”

“…(2.4) indicates that if theχ 0 1 as the light DM candidate annihilated in early universe mainly by s-channel exchange of a Z boson or a SM-like Higgs boson [41,43], an upper bound on µ has to be imposed to forbid its overproduction. Similarly an upper bound on slepton mass can be obtained if the DM annihilation proceeded mainly by t/uchannel slepton mediation.…”

Blind spots for neutralino dark matter in the NMSSM

“…refs. [14][15][16][17][18][19][20] and references therein. 1 However, conditions for blind spots in the NMSSM have not been discussed in the literature so far.…”