1,831 research outputs found
CP sensitive observables in chargino production and decay into a W boson
We study CP sensitive observables in chargino production in electron-positron
collisions with subsequent two-body decay of one chargino into a W boson. We
identify the CP odd elements of the W boson density matrix and propose CP
sensitive triple-product asymmetries of the chargino decay products. We
calculate the density-matrix elements, the CP asymmetries and the cross
sections in the Minimal Supersymmetric Standard Model with complex parameters
\mu and M_1 for an e+ e- linear collider with \sqrt{s} = 800 GeV and
longitudinally polarized beams. The asymmetries can reach 7% and we discuss the
feasibility of measuring these asymmetries.Comment: 23 pages, 7 figure
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
SUSY--QCD corrections to scalar quark decays into charginos and neutralinos
We calculate the supersymmetric QCD corrections in order to the
decays \squark_i \to q' \chargino_j (i,j = 1,2) and \squark_i \to q
\neutralino_k (k = 1,...4) within the Minimal Supersymmetric Standard Model.
In particular we consider the decays of squarks of the third generation,
\stop_i and \sbottom_i (i = 1,2), where the left--right mixing must be
taken into account. The corrections turn out to be of about 10\%, except for
higgsino--like charginos or neutralinos, where they can go up to 40\%.Comment: 15 pages (including 5 figures). Tiny corrections in the text are
made. An acknowledgement is added. Figures 2 - 5 are replaced by new ones
(change in one curve in each figure). To be published in Phys. Lett.
CP violation in chargino production and decay into sneutrino
We study CP odd asymmetries in chargino production E+ E- --> ~Chi(+-)(1)
\~Chi(-+)(2) and the subsequent two-body decay of one chargino into a
sneutrino. We show that in the Minimal Supersymmetric Standard Model with
complex parameter \mu the asymmetries can reach 30 %. We discuss the
feasibility of measuring these asymmetries at a linear collider with \sqrt{s} =
800 GeV and longitudinally polarized beams.Comment: 10 pages, 3 figure
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
Standard Model and Beyond
We first discuss the basic features of electroweak 1-loop corrections in the
Standard Model. We also give a short and elementary review on Higgs boson
searches, grand unification, supersymmetry and extra dimensions.Comment: 20 pages, LaTeX, 7 eps figures, uses ws-procs9x6.cls, lecture given
by A. Bartl at the VII School on Non-Accelerator Astroparticle Physics,
Trieste, Italy, July 26 - August 6, 200
CP asymmetries in scalar bottom quark decays
We propose CP asymmetries based on triple product correlations in the decays
sbottom_m -> top chargino_j with subsequent decays of top and chargino_j. For
the subsequent chargino_j decay into a leptonic final state l^- \nu
neutralino_1 we consider the three possible decay chains chargino_j -> l^-
sneutrino -> l^- \nu neutralino_1, chargino_j -> slepton_n \nu -> l^- \nu
neutralino_1 and chargino_j -> W^- neutralino_1 -> l^- \nu neutralino_1. We
consider two classes of CP asymmetries. In the first class it must be possible
to distinguish between different leptonic chargino_j decay chains, whereas in
the second class this is not necessary. We consider also the 2-body decay
chargino_j -> W^- neutralino_1, and we assume that the momentum of the W boson
can be measured. Our framework is the minimal supersymmetric standard model
with complex parameters. The proposed CP asymmetries are non-vanishing due to
non-zero phases for the parameters \mu and/or A_b. We present numerical results
and estimate the observability of these CP asymmetries.Comment: 27 page
Effects of CP phases on the Phenomenology of SUSY Particles
We review our recent studies on the effects of CP-violating supersymmetric
(SUSY) parameters on the phenomenology of neutralinos, charginos and third
generation squarks. The CP-even branching ratios of the squarks show a
pronounced dependence on the phases of A_t, A_b, mu and M_1 in a large region
of the supersymmetric parameter space, which can be used to get information on
these phases. In addition we have studied CP-odd observables, like asymmetries
based on triple product correlations. In neutralino and chargino production
with subsequent three-body decays these asymmetries can be as large as 20%.Comment: 10 pages, LaTeX, 4 eps figures, uses ws-procs9x6.cls, invited plenary
talk presented by A. Bartl at the "10th International Symposium on Particles,
Strings and Cosmology (PASCOS'04/NathFest)", Northeastern University, Boston,
MA, August 16-22, 200
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
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