We calculate the two-loop contributions to the electric dipole moments of the electron and the neutron mediated by charged Higgs in a generic supersymmetric theories. The new contributions are ...originated from the potential CP violation in the trilinear couplings of the charged Higgs bosons to the scalar-top or the scalar-bottom quarks. These couplings did not receive stringent constraints directly. We find observable effects for a sizable portion of the parameter space related to the third generation scalar-quarks in the minimal supersymmetric standard model.
Data collected at the Z resonance using the DELPHI detector at LEP are used to determine the charged hadron multiplicity in gluon and quark jets as a function of a transverse momentum-like scale. The ...colour factor ratio,
C
A
/
C
F
, is directly observed in the increase of multiplicities with that scale. The smaller than expected multiplicity ratio in gluon to quark jets is understood by differences in the hadronization of the leading quark or gluon. From the dependence of the charged hadron multiplicity on the opening angle in symmetric three-jet events the colour factor ratio is measured to be:
C
A/C
F=2.246±0.062
(stat.)±0.080
(syst.)±0.095
(theo.)
The fragmentation functions of quarks and gluons are measured in various three-jet topologies in Z decays from the full data set collected with the Delphi detector at the Z resonance between 1992 and ...1995. The results at different values of transverse momentum-like scales are compared. A parameterization of the quark and gluon fragmentation functions at a fixed reference scale is given. The quark and gluon fragmentation functions show the predicted pattern of scaling violations. The scaling violation for quark jets as a function of a transverse momentum-like scale is in a good agreement with that observed in lower energy \({\rm e}^+{\rm e}^-\) annihilation experiments. For gluon jets it appears to be significantly stronger. The scale dependences of the gluon and quark fragmentation functions agree with the prediction of the DGLAP evolution equations from which the colour factor ratio \(C_A/C_F\) is measured to be:
An updated analysis using about 1.5 million events recorded at s=MZ\sqrt{s} = M_Zs=MZ with the DELPHI detector in 1994 is presented. Eighteen infrared and collinear safe event shape observables are ...measured as a function of the polar angle of the thrust axis. The data are compared to theoretical calculations in O(αs2){\cal O} (\alpha_s^2)O(αs2) including the event orientation. A combined fit of αs\alpha_sαs and of the renormalization scale xμx_{\mu}xμ in O(αs2\cal O(\alpha_s^2O(αs2) yields an excellent description of the high statistics data. The weighted average from 18 observables including quark mass effects and correlations is αs(MZ2)=0.1174±0.0026\alpha_s(M_Z^2) = 0.1174 \pm 0.0026αs(MZ2)=0.1174±0.0026. The final result, derived from the jet cone energy fraction, the observable with the smallest theoretical and experimental uncertainty, is αs(MZ2)=0.1180±0.0006(exp.)±0.0013(hadr.)±0.0008(scale)±0.0007(mass)\alpha_s(M_Z^2) = 0.1180 \pm 0.0006 (exp.) \pm 0.0013 (hadr.) \pm 0.0008 (scale) \pm 0.0007 (mass)αs(MZ2)=0.1180±0.0006(exp.)±0.0013(hadr.)±0.0008(scale)±0.0007(mass). Further studies include an αs\alpha_sαs determination using theoretical predictions in the next-to-leading log approximation (NLLA), matched NLLA and O(αs2\cal O(\alpha_s^2O(αs2) predictions as well as theoretically motivated optimized scale setting methods. The influence of higher order contributions was also investigated by using the method of Pad\'{e} approximants. Average αs\alpha_sαs values derived from the different approaches are in good agreement. (arXiv)
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