b ---> s gamma constraints on the minimal supergravity model with large tan Beta

Dec, 1997
20 pages
Published in:
  • Phys.Rev.D 58 (1998) 015007
e-Print:
Report number:
  • FSU-HEP-971104,
  • UH-511-887-97,
  • UM-TH-97-19

Citations per year

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Abstract:
In the minimal supergravity model (mSUGRA), as the parameter tanβ\tan\beta increases, the charged Higgs boson and light bottom squark masses decrease, which can potentially increase contributions from tH±tH^\pm, \tg\tb_j and \tz_i\tb_j loops in the decay bsγb\to s\gamma. We update a previous QCD improved bsγb\to s\gamma decay calculation to include in addition the effects of gluino and neutralino loops. We find that in the mSUGRA model, loops involving charginos also increase, and dominate over tWtW, tH±tH^\pm, \tg\tq and \tz_i\tq contributions for \tan\beta\agt 5-10. We find for large values of tanβ35\tan\beta \sim 35 that most of the parameter space of the mSUGRA model for μ<0\mu <0 is ruled out due to too large a value of branching ratio B(bsγ)B(b\to s\gamma). For μ>0\mu >0 and large tanβ\tan\beta, most of parameter space is allowed, although the regions with the least fine-tuning (low m0m_0 and m1/2m_{1/2}) are ruled out due to too low a value of B(bsγ)B(b\to s\gamma). We compare the constraints from bsγb\to s\gamma to constraints from the neutralino relic density, and to expectations for sparticle discovery at LEP2 and the Fermilab Tevatron ppˉp\bar p colliders. Finally, we show that non-universal GUT scale soft breaking squark mass terms can enhance gluino loop contributions to bsγb\to s\gamma decay rate even if these are diagonal.
  • bottom
  • quark: radiative decay
  • strangeness
  • quark: branching ratio
  • supergravity: constraint
  • quantum chromodynamics
  • Feynman graph: higher-order
  • dark matter
  • LSP
  • electron positron: annihilation