1,427 research outputs found
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
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
Beam Polarization and Spin Correlation Effects in Chargino Production and Decay
We study chargino production e^+ e^- -> chi^+_1 chi^-_1 and the subsequent
leptonic decay chi^-_1\to chi^0_1 e^- nu_e including the complete spin
correlations between production and decay. We work out the advantages of
polarizing the e^+ and e^- beams. We study in detail the polarized cross
sections, the angular distribution and the forward--backward asymmetry of the
decay electron. They can be used to determine the sneutrino mass
m_{\tilde{\nu}_e}.Comment: 14 pages, 17 postscript figures, latex using epsfi
Impact of e^+ and e^- Beam Polarization on Chargino and Neutralino Production at a Linear Collider
We study the production processes e^+ e^- -> chi^+_i chi^-_j, i,j=1,2, and
e^+ e^- -> chi^0_m chi^0_n, m,n=1,...,4, working out the advantages of
polarizing both beams. For e^+ e^- -> chi^+_1 chi^-_1 with chi^-_1 -> chi^0_1
e^- nu and e^+ e^- -> chi^0_1 chi^0_2 with chi^0_2 -> chi^0_1 e^+ e^- we
perform a detailed analysis, including the complete spin correlations between
production and decay. We analyze the forward--backward asymmetry of the decay
electron for various beam polarizations. We also study polarization asymmetries
in e^+ e^- -> chi^0_1 chi^0_2. These asymmetries strongly constrain the gaugino
parameter M_1 and the masses m_{\tilde{e}_L}, m_{\tilde{e}_R}, m_{\tilde{nu}}
also if m_{\tilde{e}_{L,R}}, m_{\tilde{nu}} > sqrt{s}/2. We give numerical
predictions for three scenarios for a linear collider with sqrt{s}=500-1000
GeV.Comment: 26 pages, 26 postscript figures, latex using epsfi
Exploiting Spin Correlations in Neutralino Production and Decay with Polarized e^- and e^+ Beams
We study the production process e^+ e^- -> chi^0_1 chi^0_2 and the subsequent
decay chi^0_2 -> chi^0_1 l^+ l^- with polarized e^+ and e^- beams, including
the spin correlations between production and decay. We work out the advantages
of polarizing both beams. We study in detail the angular distribution and the
forward--backward asymmetry of the decay lepton as well as the opening angle
distribution between the decay leptons. We investigate the dependence on the
masses of tilde{e}_L and tilde{e}_R and on the mixing character of the
neutralinos. In particular we study the dependence on the gaugino mass
parameter M_1.Comment: 17 pages, 14 postscript figures, latex using epsfi
Sfermion Pair Production at Colliders
We discuss pair production of stops, sbottoms, staus and tau--sneutrinos at a
collider. We present the formulae for the production cross
sections and perform a detailed numerical analysis within the Minimal
Supersymmetric Standard Model. In particular, we consider sfermion production
near and .Comment: 21 pages, Latex, uses Revtex (included), 8 figures (included as
PS-files
A T-odd asymmetry in neutralino production and decay
We study CP-violating effects in neutralino production and subsequent decay
within the Minimal Supersymmetric Standard Model with complex parameters M_1
and mu. The observable we propose is a T-odd asymmetry based on a triple
product in neutralino production e^+ e^- -> tilde{chi}^0_i tilde{chi}^0_2, i =
1,...,4, with subsequent leptonic three-body decay tilde{chi}^0_2 ->
tilde{chi}^0_1 l^+ l^-, l = e, mu, at an e^+ e^- linear collider with sqrt{s} =
500 GeV and polarised beams. We provide compact analytical formulae for the
cross section and the T-odd asymmetry taking into account the complete spin
correlations between production and decay. We give numerical predictions for
the cross section and the T-odd asymmetry. The asymmetry can go up to 10 %.Comment: 28 pages, LaTeX, 10 figures; v2: typos corrected, published versio
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
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
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