58 research outputs found
Weak-scale phenomenology of models with gauge-mediated supersymmetry breaking
We study in some detail the spectral phenomenology of models in which
supersymmetry is dynamically broken and transmitted to the supersymmetric
partners of the quarks, leptons and gauge bosons, and the Higgs bosons
themselves, via the usual gauge interactions. We elucidate the parameter space
of what we consider to be the minimal model, and explore the regions which give
rise to consistent radiative electroweak symmetry breaking. We include the
weak-scale threshold corrections, and show how they considerably reduce the
scale dependence of the results. We examine the sensitivity of our results to
unknown higher-order messenger-sector corrections. We compute the superpartner
spectrum across the entire parameter space, and compare it to that of the
minimal supergravity-inspired model. We delineate the regions where the
lightest neutralino or tau slepton is the next-to-lightest supersymmetric
particle, and compute the lifetime and branching ratios of the NLSP. In
contrast to the minimal supergravity-inspired model, we find that the lightest
neutralino can have a large Higgsino component, of order 50%. Nevertheless, the
neutralino branching fraction to the gravitino and the light Higgs boson
remains small, < 10^{-4}, so the observation of such a decay would point to a
non-minimal Higgs sector.Comment: 22 pages, 16 figures, published versio
Radiative Corrections to Neutralino and Chargino Masses in the Minimal Supersymmetric Model
We determine the neutralino and chargino masses in the MSSM at one-loop. We
perform a Feynman diagram calculation in the on-shell renormalization scheme,
including quark/squark and lepton/slepton loops. We find generically the
corrections are of order 6%. For a 20 GeV neutralino the corrections can be
larger than 20%. The corrections change the region of
parameter space which is ruled out by LEP data. We demonstrate that, e.g., for
a given and the lower limit on the parameter can shift
by 20 GeV.Comment: 11 pages, JHU-TIPAC-930030, PURD-TH-93-13, uses epsf.sty, 6 uuencoded
postscript figures, added one sentence and a referenc
Anomalous prompt photon production in hadronic collisions at low-
We investigate the discrepancy that exists at low- between
the next--to--leading order QCD calculations of prompt photon production and
the measured cross section. The central values of the measured cross section
are of order 100\% larger than QCD predictions in this region. It has been
suggested that the bremsstrahlung contribution may account for this
discrepancy. The quark fragmentation function has not been
measured and an exactly known asymptotic form is normally used in calculations.
We examine the effect of much larger fragmentation functions on the QCD
predictions. After illustrating the effect of the large fragmentation functions
in some detail for recent CDF data at =1.8~TeV, we perform a
fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV.
While a large fragmentation function normalization may prove to play an
important role in resolving the discrepancy, the present theoretical and
experimental uncertainties prevent any definite normalization value from being
determined.Comment: 14 pages, LBL-33122 and UCB-PTH-92/38. 13 figures available by email,
specify postscript or topdrawe
Radiative corrections to the Higgs boson decay rate in the minimal supersymmetric model
We consider radiative corrections to the decay rate
of the heavy {\it CP}-even Higgs boson of the minimal supersymmetric model to
two bosons. We perform a one loop Feynman diagram calculation in the
on-mass-shell renormalization scheme, and include the third generation of
quarks and squarks. The tree level rate is suppressed by a mixing angle factor
and decreases as for large . The corrected rate overcomes this
suppression and increases with for ~GeV. The corrections can
be very large and depend in detail on the top squark masses and -term, as
well as the supersymmetric Higgs mass parameter .Comment: 22 pages, 9 figures available from authors, UCB-PTH-92/23 and
LBL-3249
Supersymmetric Electroweak Corrections to Heavier Top Squark Decay into Lighter Top Squark and Neutral Higgs Boson
We calculate the Yukawa corrections of order , and
to the widths of the decays in the Minimal Supersymmetric Standard
Model, and perform a detailed numerical analysis. We also compare the results
with the ones presented in an earlier literature, where the SUSY-QCD corrections to the same three decay processes have
been calculated.
Our numerical results show that for the decays , , the Yukawa corrections are
significant in most of the parameter range, which can reach a few ten percent,
and for the decay , the Yukawa corrections are
relatively smaller, which are only a few percent. The numerical calculations
also show that using the running quark masses and the running trilinear
coupling , which include the QCD, SUSY-QCD, SUSY-Electroweak effects and
resume all high order ()-enhanced effects, can vastly improve the
convergence of the perturbation expansion. We also discuss the effects of the
running of the higgsino mass parameter on the corrections, and find that
they are significant, too, especially for large .Comment: 37 pages, 19 eps figure
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