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1.
G. Moortgat-Pick H. Fraas 《The European Physical Journal C - Particles and Fields》2002,25(2):189-197
The consequences of CP and CPT invariance for production and subsequent decay of Dirac and Majorana fermions in polarized fermion-antifermion annihilation
are analytically studied. We derive general symmetry relations for the production spin density matrix and for the three-particle
decay matrices and obtain constraints for the polarization and the spin-spin correlations of Dirac and Majorana fermions.
We prove that only for Majorana fermions the energy and opening angle distribution factorizes exactly into contributions from
production and decay if CP is conserved.
Received: 6 November 2001 / Revised version: 23 April 2002 / Published online: 12 July 2002 相似文献
2.
Beam polarization at e+-e– linear colliders will be a powerful tool for high precision analyses. Often it is assumed that the full information from polarization effects is provided by polarization of the electron beam and no further information can be obtained by the simultaneous polarization of the positrons. In this paper we point out the advantages of polarizing both beams, and summarize the polarization-related results of the Higgs, Electroweak, QCD, SUSY and Alternative Theories working groups of the ECFA/DESY workshop for a planned linear collider operating in the energy range s = 500-800 GeV. 相似文献
3.
H. Fraas F. Franke G. Moortgat-Pick F. von der Pahlen A. Wagner 《The European Physical Journal C - Particles and Fields》2003,29(4):587-595
We study chargino pair production on the heavy Higgs resonances at a muon collider in the MSSM. At
GeV cross sections up to 2 pb are reached depending on the supersymmetric scenario and the beam energy spread. The resonances of the scalar and pseudoscalar Higgs bosons may be separated for
. Our aim is to determine the ratio of the chargino couplings to the heavy scalar and pseudoscalar Higgs boson independently of the specific chargino decay characteristics. The precision of the measurement depends on the energy resolution of the muon collider and on the error in the measurement of the cross sections of the non-Higgs channels including an irreducible standard model background. With a high energy resolution the systematic error can be reduced to the order of a few percent.Received: 6 March 2003, Revised: 21 May 2003, Published online: 3 July 2003 相似文献
4.
J. Ellis F. Moortgat G. Moortgat-Pick J. M. Smillie J. Tattersall 《The European Physical Journal C - Particles and Fields》2009,60(4):633-651
We study the potential observation at the LHC of CP-violating effects in stop production and subsequent cascade decays,
,
,
, within the Minimal Supersymmetric Standard Model. We study T-odd asymmetries based on triple products between the different
decay products. There may be a large CP asymmetry at the parton level, but there is a significant dilution at the hadronic
level after integrating over the parton distribution functions. Consequently, even for scenarios where large CP intrinsic
asymmetries are expected, the measurable asymmetry is rather small. High luminosity and precise measurements of masses, branching
ratios and CP asymmetries may enable measurements of the CP-violating parameters in cascade decays at the LHC. 相似文献
5.
6.
G. Moortgat-Pick H. Fraas A. Bartl W. Majerotto 《The European Physical Journal C - Particles and Fields》1999,9(3):521-534
We study the production of neutralinos with polarized beams and the subsequent decays and , including the complete spin correlations between production and decay. We present analytical formulae for the differential
cross section of the combined process of production and decay of neutralinos. We also allow for complex couplings. The spin
correlations have a strong influence on the decay angular distributions and the corresponding forward–backward asymmetries.
They are very sensitive to the SUSY parameters and depend strongly on the beam polarizations. We present numerical results
for the cross section and the electron forward–backward asymmetry for , . We study the dependence on the parameter for various mass splittings between and and different beam polarizations.
Received: 28 March 1999 / Published online: 28 May 1999 相似文献
7.
C. Bl?chinger H. Fraas G. Moortgat-Pick W. Porod 《The European Physical Journal C - Particles and Fields》2002,24(2):297-310
We investigate selectron pair production and decay in e
-
e
-
scattering and e
+
e
-
annihilation with polarized beams taking into account neutralino mixing as well as initial state radiation and beamstrahlung
corrections. One of the main advantages of having both modes at disposal is their complementarity concerning the threshold
behavior of selectron pair production. In e
-
e
-
the cross sections at threshold for and increase proportional to the momentum of the selectron and in e
+
e
-
that for . Measurements at threshold with polarized beams can be used to determine the selectron masses precisely. Moreover we discuss how polarized electron and positron beams can be used to establish directly the weak quantum
numbers of the selectrons. We also use selectron pair production to determine the gaugino mass parameter M1. This is of particular interest for scenarios with non-universal gaugino masses at a high scale resulting in at the electroweak scale. Moreover, we consider also the case of non-vanishing selectron mixing and demonstrate that it leads
to a significant change in the phenomenology of selectrons.
Received: 30 January 2002 / Published online: 8 May 2002 相似文献
8.
9.
A. Bartl H. Fraas S. Hesselbach K. Hohenwarter-Sodek T. Kernreiter G. Moortgat-Pick 《The European Physical Journal C - Particles and Fields》2007,51(1):149-161
We study CP violation in chargino production and decay in the minimal supersymmetric standard model (MSSM) with complex parameters
at an e+e- linear collider with longitudinally polarised beams. We investigate CP-sensitive asymmetries by means of triple product correlations
and study their dependence on the complex parameters M1 and μ. We give numerical predictions for the asymmetries and their measurability at the future International Linear Collider.
Our results show that the CP asymmetries can be measured in a large region of the MSSM parameter space. 相似文献
10.