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Title: On the sbottom resonance in dark matter scattering

A resonance in the neutralino-nucleus elastic scattering cross section is usually purported when the neutralino-sbottom mass difference m{sub b-tilde}−m{sub χ} is equal to the bottom quark mass m{sub b} ∼ 4 GeV. Such a scenario has been discussed as a viable model for light ( ∼ 10 GeV) neutralino dark matter as explanation of possible DAMA and CoGeNT direct detection signals. Here we give physical and analytical arguments showing that the sbottom resonance may actually not be there. In particular, we show analytically that the one-loop gluon-neutralino scattering amplitude has no pole at m{sub b-tilde} = m{sub χ}+m{sub b}, while by analytic continuation to the regime m{sub b-tilde} < m{sub χ}, it develops a pole at m{sub b-tilde} = m{sub χ}−m{sub b}. In the limit of vanishing gluon momenta, this pole corresponds to the only cut of the neutralino self-energy diagram with a quark and a squark running in the loop, when the decay process χ→ Q-tilde +Q becomes kinematically allowed. The pole can be interpreted as the formation of a b-tilde b-bar qqq or b-tilde *bqqq resonant state (where qqq are the nucleon valence quarks), which is however kinematically not accessible if the neutralino is the LSP. Our analysismore » shows that the common practice of estimating the neutralino-nucleon cross section by introducing an ad-hoc pole at m{sub b-tilde} = m{sub χ}+m{sub b} into the effective four-fermion interaction (also including higher-twist effects) should be discouraged, since it corresponds to adding a spurious pole to the scattering process at the center-of-mass energy (s){sup 1/2} ≅ m{sub χ} ≅ m{sub b-tilde}−m{sub b}. Our considerations can be extended from the specific case of supersymmetry to other similar cases in which the dark matter particle scatters off nucleons through the exchange of a b-flavored state almost degenerate in mass with the dark matter particle, such as for instance in theories with extra dimensions and in other mass-degenerate dark matter scenarios recently discussed in the literature.« less
Authors:
 [1] ;  [2]
  1. Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830 (United States)
  2. Department of Physics, Sogang University, Seoul (Korea, Republic of)
Publication Date:
OSTI Identifier:
22282626
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 10; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; B QUARKS; CROSS SECTIONS; ELASTIC SCATTERING; FERMI INTERACTIONS; FLAVOR MODEL; GEV RANGE; GLUONS; MASS DIFFERENCE; NEUTRALINOS; NONLUMINOUS MATTER; NUCLEONS; SCATTERING AMPLITUDES; SELF-ENERGY; SPARTICLES; SUPERSYMMETRY