1,381 research outputs found
A CP asymmetry in e^+e^- \to \chi^0_i\chi^0_j \to \chi^0_j \tau stau_k with tau polarization
We propose a CP-odd asymmetry in the supersymmetric process e^+e^- \to
\chi^0_i \chi^0_j \to \chi^0_j \tau stau_k by means of the transverse \tau
polarization. We calculate the asymmetry and cross sections at a future linear
collider in the 500 GeV c.m.s. energy range with longitudinal polarized beams
and high luminosity. We work in the Minimal Supersymmetric Standard Model with
complex parameters \mu, M_1 and A_\tau. The asymmetry can reach values up to 60
%. We also estimate the sensitivity for measuring the \tau polarization
necessary to probe the CP asymmetry.Comment: 12 pages, 7 figure
Impact of CP phases on stop and sbottom searches
We study the decays of top squarks (stop_{1,2}) and bottom squarks
(sbottom_{1,2}) in the Minimal Supersymmetric Standard Model (MSSM) with
complex parameters A_t, A_b, mu and M_1. We show that including the
corresponding phases substantially affects the branching ratios of stop_{1,2}
and sbottom_{1,2} decays in a large domain of the MSSM parameter space. We find
that the branching ratios can easily change by a factor of 2 and more when
varying the phases. This could have an important impact on the search for
stop_{1,2} and sbottom_{1,2} and the determination of the MSSM parameters at
future colliders.Comment: 17 pages, 5 figures, LaTeX2
Selectron production at an e-e- linear collider with transversely polarized beams
We study selectron production at an e-e- linear collider. With the help of
transverse beam polarizations, we define CP sensitive observables in the
production process e- e- --> selectron_L selectron_R. This process proceeds via
t-channel and u-channel exchange of neutralinos, and is sensitive to CP
violation in the neutralino sector. We present numerical results and estimate
the significances to which the CP sensitive observables can be measured.Comment: 14 page
CP violating angular asymmetries of b and bbar quarks in e+e- -> t tbar
We obtain analytical formulae for the cross section and the angular
distributions of the b(bbar) quarks in the process e+e- -> t tbar, with t -> W+
b (tbar -> W- bbar) assuming CP violation in the \gamma t tbar and Z t tbar
vertices. We present CP violating asymmetries, which measure separately the
real and imaginary parts of the electroweak dipole moment form factors of the
top, d^{\gamma}(s) and d^{Z}(s). We give a numerical analysis of these
asymmetries within the Minimal Supersymmetric Standard Model with complex
parameters. They turn out to be of order <= 10^{-3}.Comment: 22 pages LaTeX with 3x3 figures included; some definitions for
polarization asymmetries and some notations are changed and some references
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Impact of bosonic decays on the search for stau_2 and tau-sneutrino
We perform a detailed study of the decays of the heavier tau slepton (stau_2)
and tau-sneutrino (snu_tau) in the Minimal Supersymmetric Standard Model
(MSSM). We show that the decays into Higgs or gauge bosons, i.e. stau_2 ->
stau_1 + (h^0, H^0, A^0 or Z^0), stau_2 -> snu_tau + (H^- or W^-), and snu_tau
-> stau_1 + (H^+ or W^+), can be very important due to the sizable tau Yukawa
coupling and large mixing parameters of stau. Compared to the decays into
fermions, such as stau_2 -> tau + neutralino_i and stau_2 -> nu_tau +
chargino_j^-, these bosonic decay modes can have significantly different decay
distributions. This could have an important influence on the search for stau_2
and snu_tau and the determination of the MSSM parameters at future colliders.Comment: 12 pages, 3 figures, LaTeX2
CP sensitive observables in chargino production with transverse beam polarization
We consider the process e^+e^-\to\ti\chi^+_i\ti\chi^-_j at a linear
collider with transverse beam polarization. We investigate the
influence of the CP phases on azimuthal asymmetries in
e^+e^-\to\ti\chi^+_i\ti\chi^-_j with subsequent two-body decays
\ti\chi^-_j\to \ti\nu_{\ell}\ell^- and \ti\chi^-_j\to W^-\ti\chi^0_1. We
show that triple product correlations involving the transverse beam
polarization vanish if at least one subsequent chargino decay is not observed.
We derive this result within the Minimal Supersymmetric Standard Model (MSSM)
with complex parameters, however, it holds also in the general MSSM with SUSY
flavour violation.Comment: 19 pages, 6 figure
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.
Associate Sneutrino-Neutralino/Chargino Production at LEPxLHC
We examine for representative gaugino-higgsino mixing scenarios
sneutrino-neutralino and sneutrino-chargino production in deep inelastic
ep-scattering at the cm-energy of 1.8 TeV. The cross sections for
sneutrino-chargino production are more than one order of magnitude bigger than
those for sneutrino-squark production. Also for zino-like neutralinos we find
cross sections at least comparable to those for sneutrino-squark production.Comment: 9 pages, report UWITP-94/
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