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Register a new userCP Violation in the 3 Jet and 4 Jet Decays of the Z Boson at GigaZ
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We review CP-violating effects in Z --> 3 jet and Z --> 4 jet decays, assuming the presence of CP-violating effective Z b bbar G and Z b bbar G G couplings. Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic of a strong interaction.
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We analyse CP-violating effects in Z to 4 jet decays, assuming the presence of CP-violating effective $Z b bar{b} G$ and $Z b bar{b} G G$ couplings. We discuss the influence of these couplings on the decay width. Furthermore, we propose various strategies of a direct search for such CP-violating couplings by using different CP-odd observables. The present data of LEP 1 should give significant information on the couplings.
Precise predictions are provided for the production of a $mathrm{Z}$-boson and a $mathrm{b}$-jet in hadron-hadron collisions within the framework of perturbative QCD, at $mathcal{O}(alpha_s^3)$. To obtain these predictions we perform the first calculation of a hadronic scattering process involving the direct production of a flavoured-jet at next-to-next-to-leading order accuracy in massless QCD, and extend techniques to also account for the impact of finite heavy-quark mass effects. The predictions are compared to CMS data obtained in $mathrm{pp}$ collisions at a centre-of-mass energy of $8~mathrm{TeV}$, which are the most precise data from Run I of the LHC for this process, where a good description of the data is achieved. To allow this comparison we have performed an unfolding of the data, which overcomes the long-standing issue that the experimental and theoretical definitions of jet flavour are incompatible.
The BaBar detector and SLAC PEP-II asymmetric e+e- collider tuned to the Y(4s) resonance has collected around 23M B0 anti-B0 pairs in year 2000. The total data sample for run 1 is 20.7fb-1, using this data we present the study of sin2beta, with samples of B0 --> J/Psi KOS, B0 --> psi(2S) K0S and B0 --> J/Psi KOL decays. The measured value is sin2beta 0.34+/-0.20 (stat) +/- 0.05 (syst),. In addition, we present preliminary measurements of charged and neutral B meson lifetimes and B0-anti B0 oscillation frequency.
Precision tests of the Kobayashi-Maskawa model of CP violation are discussed, pointing out possible signatures for other sources of CP violation and for new flavor-changing operators. The current status of the most accurate tests is summarized.
The mean charge multiplicity in hadronic three-jet Z decays has been measured with the DELPHI detector as a function of the event topology and compared with recent theoretical calculations. The QCD colour factor ratio C_A/C_F was determined, and the gluon contribution to this multiplicity was extracted giving a measurement of the mean charge multiplicity of a two-gluon colour-singlet system as a function of the effective c.m. energy covering the range from 16 to 52 GeV.
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