1,469 research outputs found
The decays gluino -> stop_1 b-quark W and gluino -> stop_1 c-quark and phenomenological implications in supersymmetric theories
We show that the decay gluino -> stop_1 b-quark W is important and can even
be dominant in the region of parameter space where it is kinematically allowed.
We discuss phenomenological implications within the Minimal Supersymmetric
Standard Model and models with broken R-parity. We consider the flavour
diagonal case as well as a possible mixing between squarks of different
generations. In the latter case also the decay gluino -> stop_1 c-quark is
potentially important. We show that the decay gluino -> stop_1 b-quark W is
sensitive to the stop mixing angle. Furthermore we demonstrate that in
scenarios with a higgsino--like LSP the gluino decays mainly into final states
containing top quarks or a light stop if allowed by kinematics.Comment: LaTex, 15 pages, 8 figures, uses JHEP3.cls (included), v2, improved
discussion of gluino -> stop_1 c-quark, conclusions unchanged, version to
appear in JHE
Tau-Sleptons and Tau-Sneutrino in the MSSM with Complex Parameters
We present a phenomenological study of tau-sleptons stau_1,2 and
tau-sneutrino in the Minimal Supersymmetric Standard Model with complex
parameters A_tau, mu and M_1. We analyse production and decays of stau_1,2 and
tau-sneutrino at a future e^+ e^- collider. We present numerical predictions
for the important decay rates, paying particular attention to their dependence
on the complex parameters. The branching ratios of the fermionic decays of
stau_1 and tau-sneutrino show a significant phase dependence for tan(beta) <
10. For tan(beta) > 10 the branching ratios for the stau_2 decays into Higgs
bosons depend very sensitively on the phases. We show how information on the
phase phi(A_tau) and the other fundamental stau parameters can be obtained from
measurements of the stau masses, polarized cross sections and bosonic and
fermionic decay branching ratios, for small and large tan(beta) values. We
estimate the expected errors for these parameters. Given favorable conditions,
the error of A_tau is about 10% to 20%, while the errors of the remaining stau
parameters are in the range of approximately 1% to 3%. We also show that the
induced electric dipole moment of the tau-lepton is well below the current
experimental limit.Comment: LaTex, 25 pages, 11 figures (included); v2: extended discussion on
error determination, version to appear in Phys.Rev.
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
CP asymmetries in the supersymmetric trilepton signal at the LHC
In the CP-violating Minimal Supersymmetric Standard Model, we study the
production of a neutralino-chargino pair at the LHC. For their decays into
three leptons, we analyze CP asymmetries which are sensitive to the CP phases
of the neutralino and chargino sector. We present analytical formulas for the
entire production and decay process, and identify the CP-violating
contributions in the spin correlation terms. This allows us to define the
optimal CP asymmetries. We present a detailed numerical analysis of the cross
sections, branching ratios, and the CP observables. For light neutralinos,
charginos, and squarks, the asymmetries can reach several 10%. We estimate the
discovery potential for the LHC to observe CP violation in the trilepton
channel.Comment: 39 pages, 8 figures, version to appear in EPJC, discussion(s) added,
typo in (D.79), (D.118) corrected, new Fig. 7; The European Physical Journal
C, Volume 72, Issue 3, 201
Triple product correlations in top squark decays
We propose several T-odd asymmetries in the decay chains of the top squarks
and and , for . We
calculate the asymmetries within the Minimal Supersymmetric Standard Model with
complex parameters , and . We give the analytic formulae for
the decay distributions. We present numerical results for the asymmetries and
estimate the event rates necessary to observe them. The largest T-odd asymmetry
can be as large as 40%.Comment: 26 pages, 5 figures; misprints corrected; reference adde
Top Squarks and Bottom Squarks in the MSSM with Complex Parameters
We present a phenomenological study of top squarks (~t_1,2) and bottom
squarks (~b_1,2) in the Minimal Supersymmetric Standard Model (MSSM) with
complex parameters A_t, A_b, \mu and M_1. In particular we focus on the CP
phase dependence of the branching ratios of (~t_1,2) and (~b_1,2) decays. We
give the formulae of the two-body decay widths and present numerical results.
We find that the effect of the phases on the (~t_1,2) and (~b_1,2) decays can
be quite significant in a large region of the MSSM parameter space. This could
have important implications for (~t_1,2) and (~b_1,2) searches and the MSSM
parameter determination in future collider experiments. We have also estimated
the accuracy expected in the determination of the parameters of ~t_i and ~b_i
by a global fit of the measured masses, decay branching ratios and production
cross sections at e^+ e^- linear colliders with polarized beams. Analysing two
scenarios, we find that the fundamental parameters apart from A_t and A_b can
be determined with errors of 1% to 2%, assuming an integrated luminosity of 1
ab^-1 and a sufficiently large c.m.s. energy to produce also the heavier ~t_2
and ~b_2 states. The parameter A_t can be determined with an error of 2 - 3%,
whereas the error on A_b is likely to be of the order of 50%.Comment: 31 pages, 8 figures, comments and references added, conclusions
unchanged; version to appear in Phys. Rev.
SUSY-QCD corrections to stop and sbottom decays into Higgs bosons
We calculate the order(\alpha_s) SUSY-QCD corrections to the widths of stop
and sbottom decays into Higgs bosons within the Minimal Supersymmetric Standard
Model. We give the complete analytical formulae paying particular attention to
the on-shell renormalization of the soft SUSY-breaking parameters. We also
perform a detailed numerical analysis of both stop and sbottom decays into all
Higgs bosons h^0, H^0, A^0, and H^\pm. We find that the SUSY-QCD corrections
are significant, mostly negative and of the order of a few ten percent.Comment: revised version, one figure and a few comments adde
Supersymmetric Electroweak Corrections to Sbottom Decay into Lighter Stop and Charged Higgs Boson
The Yukawa corrections of order ,
and to the width of sbottom decay into lighter
stop plus charged Higgs boson are calculated in the Minimal Supersymmetric
Standard Model. These corrections depend on the masses of charged Higgs boson
and lighter stop, and the parameters and . For favorable
parameter values, the corrections decrease or increase the decay widths
significantly. Especially for high values of (=30) the corrections
exceed at least 10% for both and decay. But for low
values of (=4,10) the corrections are small and the magnitudes are
less than 10%. The numerical calculations also show that using the running
bottom quark mass which includes the QCD effects and resums all high order
-enhanced effects can improve much the convergence of the
perturbation expansion.Comment: LateX, 27 pages, 13 ps figures. 12 figures updated, a figure and some
references adde
Testing the Mechanism of R-parity Breaking with Slepton LSP Decays
In supersymmetric models R-parity can be violated through either bilinear or
trilinear terms in the superpotential, or both. If charged scalar leptons are
the lightest supersymmetric particles, their decay properties can be used to
obtain information about the relative importance of these couplings. We show
that in some specific scenarios it is even possible to decide whether bilinear
or trilinear terms give the dominant contribution to the neutrino mass matrix.Comment: Intro rewritten, Fig 1 and Fig 4 slightly changed, conclusions
unchanged, 25 pages, 4 figure
CP violation in sbottom decays
We study CP asymmetries in two-body decays of bottom squarks into charginos
and tops. These asymmetries probe the SUSY CP phases of the sbottom and the
chargino sector in the Minimal Supersymmetric Standard Model. We identify the
MSSM parameter space where the CP asymmetries are sizeable, and analyze the
feasibility of their observation at the LHC. As a result, potentially
detectable CP asymmetries in sbottom decays are found, which motivates further
detailed experimental studies for probing the SUSY CP phases.Comment: 29 pages, 7 figure
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