arXiv subjects

J. I. Illana

Publications and source records attributed to J. I. Illana.

42 records · Page 3Linked to original sources

arXiv1998

Weak Electric Dipole Moments of Heavy Fermions in the MSSM

A minimal supersymmetric version of the Standard Model with complex parameters allows contributions to the weak-electric dipole moments of fermions at the one-loop level. Assuming generation-diagonal trilinear soft-susy-breaking terms and the usual GUT constraint, a set of CP-violating physical phases can be introduced. In this paper the general expressions for the one-loop contribution to the WEDM in a generic renormalizable theory are given and the size of the WEDM of the tau lepton and the b quark in such a supersymmetric model is discussed.

hep-ph↗

arXiv1997

One-loop weak dipole moments of heavy fermions in the MSSM

The MSSM predictions at the one-loop level for the weak dipole moments of the τlepton and the b quark are presented. The imaginary part of the AWMDM is of the order of the SM contribution whereas the real part may be a factor 5 (20) larger for the τ(b) in the high \tanβscenario, still a factor five below the QCD contribution in the b case. More interestingly, a contribution up to twelve orders of magnitude larger than in the SM may be obtained, already at the one-loop level, for the WEDM in a MSSM with complex parameters.

hep-ph↗

arXiv1997

One-loop MSSM Contribution to the Weak Magnetic Dipole Moments of Heavy Fermions

The MSSM predictions at the one-loop level for the weak-magnetic dipole moments of the $τ$ lepton and the $b$ quark are analysed. The entire supersymmetric parameter space is scannedwith the usual GUT constraint and common squark and slepton mass parameters. The real part of $a^W_τ$ is dominated by the chargino contribution, being the same order as the SM one or even larger in the high $\tanβ$ region whereas the imaginary part, due to Higgs boson diagrams, is negligible comparedto the SM value. The real part of$a^W_b$ is controlled mainly by charginos andalso by gluinos, when the mixing in the bottom squark sector is large, to yield, for high $\tanβ$, a contribution one order of magnitude largerthan the pure electroweak SM value but a factor five smaller than the standard QCD contribution. The imaginary part of $a^W_b$ is the same order as in the SM.

hep-ph↗

arXiv1996

The coupling of the lightest SUSY Higgs boson to two photons in the decoupling regime

We analyze the contribution of the SUSY particles to the coupling of the lightest Higgs boson to two photons in supersymmetric theories. We discuss to what extent these contributions can be large enough to allow for a discrimination between the lightest SUSY and the standard Higgs particles in the decoupling limit where all other Higgs bosons are very heavy and no supersymmetric particle has been discovered at future colliders. We find that only chargino and top squark loops can generate a sizeable difference between the standard and the SUSY Higgs-photon couplings. For masses above 250 GeV, the effect of chargino loops on the two-photon width is however smaller than $\sim 10%$ in the entire SUSY parameter space. Top squarks heavier than 250 GeV can induce deviations larger than 10% only if their couplings to the Higgs boson are large. Since top squark contributions can be sizeable, we derive the two-loop QCD correction to squark loops and show that they are well under control.

hep-ph↗

arXiv1996

Bounds on the Zγγcouplings from HERA

The possibility of testing trilinear neutral gauge boson couplings in radiative neutral current scattering at HERA is analyzed using a Monte Carlo program that includes the Standard Model at tree level and the anomalous vertices. Acceptance and isolation cuts are applied as well as optimized cuts to enhance the signal from new physics. The bounds on Zγγcouplings that can be achieved are not so stringent as present bounds, even for high luminosities, but probe a different kinematical region almost unsensitive to form factors.

hep-ph↗

arXiv1994

Non Standard Tau Pair Production in Two Photon Collisions at LEP II and Beyond

We study the sensitivity of LEP II and NLC, via two photon collisions, to the effects of anomalous $τ\overlineτ γ$ couplings. We also discuss some CP-odd observables that can be useful to disentangle the contributions from the anomalous couplings. (5 figures included via epsf appended at the end as uuencoded compressed tar postscript file).

hep-ph↗