Phenomenology of light neutralinos in view of recent results at the CERN Large Hadron Collider

A. Bottino, N. Fornengo, and S. Scopel

Phys. Rev. D 85, 095013 – Published 17 May 2012

Abstract

We review the status of the phenomenology of light neutralinos in an effective minimal supersymmetric extension of the standard model at the electroweak scale, in light of new results obtained at the CERN Large Hadron Collider. First, we consider the impact of the new data obtained by the CMS Collaboration on the search for the Higgs-boson decay into a tau pair, and by the CMS and LHCb Collaborations on the branching ratio for the decay $B_{s} \to μ^{+} + μ^{-}$ . Then, we examine the possible implications of the excess of events found by the ATLAS and CMS Collaborations in a search for a standard-model (SM)-like Higgs boson around a mass of 126 GeV, with a most likely mass region (95% C.L.) restricted to 115.5–131 GeV (global statistical significance about $2.3 σ$ ). From the first set of data, we update the lower bound of the neutralino mass to be about 18 GeV. From the second set of measurements, we derive that the excess around $m_{H}^{SM} = 126 GeV$ , which however needs a confirmation by further runs at the LHC, would imply a neutralino in the mass range $18 GeV ≲ m_{X} ≲ 38 GeV$ , with neutralino-nucleon elastic cross sections fitting well the results of the dark matter direct search experiments DAMA/LIBRA and CRESST.

Received 11 January 2012

DOI:https://doi.org/10.1103/PhysRevD.85.095013

Authors & Affiliations

A. Bottino¹, N. Fornengo¹, and S. Scopel²

¹Dipartimento di Fisica Teorica, Università di Torino Istituto Nazionale di Fisica Nucleare, Sezione di Torino via P. Giuria 1, I-10125 Torino, Italy
²Department of Physics, Sogang University Seoul, 121-742, Korea

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Vol. 85, Iss. 9 — 1 May 2012

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Figure 1
Upper bounds in the $m_{A} - \tan β$ plane, derived from searches of the neutral Higgs decays into a tau pair at the LHC. The dash-dotted line denotes the 95% C.L. upper bound reported in Ref. 38. The dashed line displays the expected upper bound (in case of no positive signal for an integrated luminosity of $3 {fb}^{- 1}$ ) as evaluated in Refs. 39, 40. The scatter plot denotes configurations of the LNM. The solid lines (some of which are labeled by numbers) denote the cosmological bound $Ω_{χ} h^{2} \leq (Ω_{CDM} h^{2})_{\max }$ for a neutralino whose mass is given by the corresponding number (in units of GeV), as obtained by Eq. (6), with $ϵ_{b} = - 0.08$ and $(Ω_{CDM} h^{2})_{\max } = 0.12$ . For any given neutralino mass, the allowed region is above the corresponding line.Reuse & Permissions
Figure 2
Relation among the Higgs masses in the LNM. In the left panel, the correlation between $m_{h}$ and $m_{A}$ is shown. In the right panel, the correlation between $m_{H}$ and $m_{A}$ is given. The horizontal (red) line and the shaded band around it denote the value of 126 GeV for the Higgs mass (and the 95% C.L. region between 115.5 GeV and 131 GeV) compatible with the excess of events observed by ATLAS [11] and CMS [12].Reuse & Permissions
Figure 3
Fractional relevance of channels in the neutralino self-annihilation cross section $\tilde{⟨ σ_{ann} v ⟩}$ appearing in Eq. (2) as a function of the neutralino mass in the LNM. The (red) points refer to annihilation through $A$ exchange; (green) crosses to annihilation through $\tilde{τ}$ exchange.Reuse & Permissions
Figure 4
Fractional relevance of channels in the neutralino-nucleon elastic-scattering cross section as a function of the neutralino mass in the LNM. From darker to lighter points: $h$ exchange, $H$ exchange, $\tilde{q}$ exchange.Reuse & Permissions
Figure 5
Neutralino-nucleon cross section $ξ σ_{scalar}^{(nucleon)}$ as a function of the neutralino mass for the LNM scan and for $g_{d, ref} = 290 MeV$ . The (red) crosses denote configurations with a heavy Higgs mass in the range compatible with the ATLAS [11] and CMS [12] excess at the LHC. The shaded areas denote the DAMA/LIBRA annual modulation regions: the upper area (vertical shade; green) refers to the case where constant values of 0.3 and 0.09 are taken for the quenching factors of Na and I, respectively [10]; the lower area (cross hatched; red) is obtained by using the energy-dependent Na and I quenching factors as established by the procedure given in Ref. 55. The gray regions are those compatible with the CRESST excess [7]. In all cases, a possible channeling effect is not included. The halo distribution functions used to extract the experimental regions are given in the text.Reuse & Permissions
Figure 6
Production cross-section ratio $R_{γ γ} \equiv [σ (g g \to H) \times BR (H \to γ γ)]_{MSSM} / [σ (g g \to h) BR (h \to γ γ)]_{SM}$ as a function of $BR (H \to γ γ)_{MSSM} / BR (h \to γ γ)_{SM}$ for the configurations discussed in Sec. 3a. Black points refer to $H$ masses in the range $115 GeV \leq m_{H} \leq 131 GeV$ , while (red) circles refer to an $H$ mass interval more focused around 126 GeV (specifically: $125 GeV \leq m_{H} \leq 127 GeV$ ).Reuse & Permissions

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