346 research outputs found
Low energy threshold corrections to neutrino masses and mixing angles
We compute the low energy threshold corrections to neutrino masses and mixing
in the Standard Model (SM) and its minimal supersymmetric version, using the
effective theory technique. We demonstrate that they stabilize the
renormalization group (RG) running with respect to the choice of the scale to
which the RG equation is integrated. This confirms the correctness of the
recent re-derivation of the RGE for the SM in hep-ph/0108005. The explicit
formulae for the low energy threshold corrections corrections can be applied to
specific models of neutrino masses and mixing.Comment: 20 pages, 2 postscript figure
ALEPH Four-Jet Excess, and Parity Violation
We review briefly the indications for some relatively light superpartners
based on the ~ ~anomaly and discuss the dependence of the potential
increase in on the assumption about ~parity (non)conservation. We
point out that the exotic 4-jet events reported by ALEPH may constitute a
signal for supersymmetry with such a light spectrum and with explicitly broken
parity. A parton level simulation shows that production of a pair of light
charginos with their subsequent baryon-number violating decays (either through
a stop or through a neutralino) could possibly give rise to this excess. The
decay \chi^- \ra \tilde{t}_R^\ast b \ra d s b with m_{\chi^-_1} \sim 60
\gev and m_{\tilde t} \sim 52 \gev leads to signatures very close to the
experimental observations.Comment: 17 pages, submited as uuencoded gz-compressed .tar file containing
LATEX file and figures. Some typos fixed and the important error in the
caption of Fig. 7 correcte
Flavour Changing Neutral Currents and Inverted Sfermion Mass Hierarchy
We study the contraints on non-flavour-blind soft supersymmetry breaking
terms coming from flavour and CP violating processes in the presence of
hierarchical Yukawa couplings, and quantify how much these constraints are
weakened in the regions of the MSSM parameter space characterized by heavy
gauginos and multi-TeV sfermion masses, respectively. We also study the
inverted sfermion mass hierarchy scenario in the context of D-term
supersymmetry breaking, and show that generic hierarchical Yukawa couplings
with arbitrary phases require first generation squarks in the few 10 TeV range.Comment: 9 pages, 6 figures. Talk given at the XLth Rencontres de Moriond on
Electroweak Interactions and Unified Theories, La Thuile, Aosta Valley,
Italy, 5-12 March 2005. V3: one reference correcte
Up-dating for the paper "The mass of the Higgs boson in the standard model from precision tests"
The bounds on the Higgs mass in the Standard Model are re-analyzed using the precision electroweak data presented at the International Europhysics Conference on High Energy Physics, Brussels, 27 July -- 2 August, 199
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