2018 Impact factor 4.843
Particles and Fields

Eur. Phys. J. C 20, 689-694 (2001)
DOI: 10.1007/s100520100695

The $b \to X_s \gamma$ rate and Higgs boson limits in the constrained minimal supersymmetric model

W. de Boer1, M. Huber1, A.V. Gladyshev2 and D.I. Kazakov2

1  Institut für Experimentelle Kernphysik, University of Karlsruhe, Postfach 6980, 76128 Karlsruhe, Germany
2  Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141 980 Dubna, Moscow Region, Russian Federation

(Received: 14 February 2001 / Revised version: 22 March 2001 / Published online: 29 June 2001 -© Springer-Verlag / Società Italiana di Fisica 2001)

New NLO $b \to X_s \gamma$ calculations have become available using resummed radiative corrections. Using these calculations we perform a global fit of the supergravity inspired constrained minimal supersymmetric model. We find that the resummed calculations show similar constraints as the LO calculations, namely that only with a relatively heavy supersymmetric mass spectrum of $\mathcal{O}$(1 TeV) the b-$\tau$ Yukawa unification and the $b \to X_s \gamma$ rate can coexist in the large $\tan\beta$ scenario. The resummed $b \to X_s \gamma$ calculations are found to reduce the renormalization scale uncertainty considerably. The low $\tan\beta$ scenario is excluded by the present Higgs limits from LEP II. The constraint from the Higgs limit in the m0,m1/2 plane is severe, if the tri li near coupling A0 at the GUT scale is fixed to zero, but is considerably reduced for $A_0\le -2m_0$. The relatively heavy SUSY spectrum required by $b \to X_s \gamma$ corresponds to a Higgs mass of $m_h=119\pm1 {(stop masses)} \pm2 ({\mathrm {theory}}) \pm3 {(top
$ GeV in the CMSSM.

© Società Italiana di Fisica, Springer-Verlag 2001