arXiv subjects

T. Kernreiter

Publications and source records attributed to T. Kernreiter.

44 records · Page 3Linked to original sources

arXiv2003

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.

hep-ph↗

arXiv2003

CP Phases, LFV, RpV & all that

Most phenomenological analyses of searches for supersymmetric particles have been performed within the MSSM with real SUSY parameters and conserved R-parity and lepton flavour. Here we summarize recent results obtained in the (s)lepton sector when one of the above assumptions is relaxed.

hep-ph↗

arXiv2003

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.

hep-ph↗

arXiv2002

CP violation in decays of the lightest supersymmetric particle with bilinearly broken R parity

Supersymmetric models with broken R-parity induced by lepton number violating terms provide a calculable framework for neutrino masses and mixings. Within models with bilinear R-parity breaking six new physical phases appear which are potential sources of novel CP-violating phenomena compared to the minimal supersymmetric extension of the standard model. We consider CP-violating observables in the decays of the lightest supersymmetric particle in this class of models. We show that: (i) Neutrino physics requires a strong correlation between three different pairs of phases, thus reducing the effective number of new phases to three. (ii) CP-violating phenomena in decays of the lightest supersymmetric particle due to new R-parity breaking phases turn out to be small, once constraints from neutrino physics are taken into account. We demonstrate that this feature does not depend on the nature of the lightest supersymmetric particle.

hep-ph↗

arXiv2002

Sfermion Precision Measurements at a Linear Collider

At future e+- e- linear colliders, the event rates and clean signals of scalar fermion production - in particular for the scalar leptons - allow very precise measurements of their masses and couplings and the determination of their quantum numbers. Various methods are proposed for extracting these parameters from the data at the sfermion thresholds and in the continuum. At the same time, NLO radiative corrections and non-zero width effects have been calculated in order to match the experimental accuracy. The substantial mixing expected for the third generation sfermions opens up additional opportunities. Techniques are presented for determining potential CP-violating phases and for extracting tan(beta) from the stau sector, in particular at high values. The consequences of possible large mass differences in the stop and sbottom system are explored in dedicated analyses.

hep-ph↗

arXiv2002

New physics searches at a Linear Collider with polarized beams

A future e+e- Linear Collider has a large physics potential for the discovery of new physics beyond the Standard Model and precision studies of the Standard Model itself. It is well suited to complement and extend the physics program of the LHC concerning the precise determination of the underlying theory. The use of polarized beams at a LC will be one of the decisive tools.

hep-ph↗

arXiv2002

A CP sensitive asymmetry in the three--body decay stop_1 -> b tau+ tau-sneutrino

We consider the three--body decay stop_1 -> b tau+ tau-sneutrino and propose the asymmetry of the tau polarization perpendicular to the decay plane as a CP sensitive observable. We calculate this asymmetry in the Minimal Supersymmetric Standard Model taking the parameters mu and A_t complex. In the parameter domain where the decay stop_1 -> b tau+ tau-sneutrino is important this asymmetry can go up to 30%. We also estimate the event rates necessary to observe this asymmetry at 90% CL.

hep-ph↗

arXiv2002

Impact of CP phases on the search for sleptons tau and nu_tau

We study the decays of the tau-sleptons (stau_{1,2}) and tau-sneutrino (snu_tau) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_tau, mu and M_1 (U(1) gaugino mass). We show that the effect of the CP phases of these parameters on the branching ratios of stau_{1,2} and snu_tau decays can be quite strong in a large region of the MSSM parameter space. This could have an important impact on the search for stau_{1,2} and snu_tau and the determination of the MSSM parameters at future colliders.

hep-ph↗