arXiv subjects

O. Kittel

Publications and source records attributed to O. Kittel.

26 records · Page 2Linked to original sources

arXiv2003

Impact of CP phases on SUSY particle production and decays

We report on the results of a phenomenological study 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. In particular we focus on the CP phase dependence of the branching ratios of stop_{1,2} and sbottom_{1,2} decays. We find that the effect of the phases on the stop_{1,2} and sbottom_{1,2} decays can be quite significant in a large region of the MSSM parameter space. We also study a CP asymmetry in sfermion decays.

hep-ph↗

arXiv2003

CP asymmetries in neutralino production in e+e- collisions

We study two CP sensitive triple-product asymmetries for neutralino production e+e- \to\tildeχ^0_i \tildeχ^0_j and the subsequent leptonic two-body decay \tildeχ^0_i \to \tilde l l, \tilde l \to \tildeχ^0_1 l, for ł= e,μ,τ. We calculate the asymmetries, cross sections and branching ratios in the Minimal Supersymmetric Standard Model with complex parameters μand M_1. We present numerical results for the asymmetries to be expected at a linear electron-positron collider in the 500 GeV range. The asymmetries can go up to 25 %. We estimate the event rates which are necessary to observe the asymmetries. Polarized electron and positron beams can significantly enhance the asymmetries and cross sections. In addition, we show how the two decay leptons can be distinguished by making use of their energy distributions.

hep-ph↗

arXiv2003

T-odd Correlations in the Decay of Scalar Fermions

We define a CP sensitive asymmetry in the sfermion decays $\ti f \to f \tiχ^0_j \ell \bar \ell, f \tiχ^0_j q \bar q$, based on triple product correlations between the momenta of the outgoing fermions. We study this asymmetry in the MSSM with complex parameters. We show that the asymmetry is sensitive to the phases of the parameters $μ$ and $M_1$. The leading contribution stems from the decay chain $\ti f\to f \tiχ^0_j\to f \tiχ^0_1 Z\to f \tiχ^0_1 \ell \bar \ell (f \tiχ^0_1 q \bar q)$, for which we obtain analytic formulae for the amplitude squared. The asymmetry can go up to 3% for $\ti f\to f \tiχ^0_1 \ell \bar \ell$, and up to 20% for $\ti f\to f \tiχ^0_1 q \bar q$. We also estimate the rates necessary to measure the asymmetry.

hep-ph↗

arXiv2003

CP violation in production of neutralinos in e+ e- collisions

We propose T-odd and CP-odd odd asymmetries in order to analyze the impact of CP violating phases in neutralino production and subsequent leptonic two-body decays. We present numerical results of these asymmetries and of the cross sections for complex parameters μ, M_1 and A_τ, which may be present in the neutralino and stau sector of the Minimal Supersymmetric Standard Model if CP is violated. The asymmetries arise on tree level and thus could be large enough to be observed at a linear e+e- collider in the \sqrt{s}=500 GeV range with high luminosity. We discuss the feasibility for measuring the asymmetries by analyzing their statistical errors. Moreover we study the beam polarization dependence of the asymmetries and of the cross sections and show that they both can be enhanced considerably.

hep-ph↗

arXiv2003

New Ideas on SUSY Searches at Future Linear Colliders

Several results obtained within the SUSY group of the ECFA/DESY linear collider study are presented: (i) a possibility to determine tan beta and the trilinear couplings A_f via polarisation in sfermion decays, (ii) the impact of complex MSSM parameters on the third generation sfermion decays, (iii) determination of CP violation in the complex MSSM via T-odd asymmetries in neutralino production and decay, and (iv) an analysis of the chargino and neutralino mass parameters at one-loop level.

hep-ph↗

arXiv2003

Impact of beam polarization on CP asymmetries in neutralino pair production

We analyze the dependence of CP-odd asymmetries on longitudinally polarized e+ and e- beams in neutralino production and subsequent leptonic two-body decays. We give numerical examples of the asymmetries and of the cross sections in the Minimal Supersymmetric Standard Model with complex parameters mu, M_1 and A_{tau} for a collider with sqrt{s}=500 GeV. We show that longitudinally polarized electron and positron beams can enhance considerably both the asymmetries and the cross sections.

hep-ph↗

arXiv2003

A CP asymmetry in e^+e^- \to χ^0_iχ^0_j \to χ^0_j τstau_k with tau polarization

We propose a CP-odd asymmetry in the supersymmetric process e^+e^- \to χ^0_i χ^0_j \to χ^0_j τstau_k by means of the transverse τpolarization. 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 μ, M_1 and A_τ. The asymmetry can reach values up to 60 %. We also estimate the sensitivity for measuring the τpolarization necessary to probe the CP asymmetry.

hep-ph↗

arXiv2003

CP asymmetries in neutralino production

We study two CP sensitive triple-product asymmetries for neutralino production e+e- \to \tildeχ^0_i \tildeχ^0_j and the subsequent leptonic two-body decays \tildeχ^0_i \to \tilde{l} l of one of the neutralinos and of the slepton \tilde{l} \to \tildeχ^0_1 l at an e+e--linear collider with \sqrt{s} = 500 GeV. We calculate the asymmetries in the Minimal Supersymmetric Standard Model with complex parameters μand M_1. We show that the largest asymmetries are 10% or 25% and estimate the event rates which are necessary to measure the asymmetries. Polarized electron and positron beams can significantly enhance the asymmetries and cross sections. In addition, we show how the two decay leptons can be distinguished by making use of their energy distributions.

hep-ph↗