34164831
Oblique electroweak corrections and new physics.
Oblique electroweak parameters {ital {tilde S}}, {ital {tilde T}}, and {ital {tilde U}}, defined so as to be nonvanishing only for physics beyond the standard model, are determined by direct use of high-statistics data from the CERN {ital e}{sup +}{ital e{minus}} collider LEP at different energy points around the {ital Z} peak. Additional information from related electroweak measurements are used as constraints. The results are {ital {tilde S}}={minus}0.76{plus minus}0.71, {ital {tilde T}}={minus}0.70{plus minus}0.49, and {ital {tilde U}}={minus}0.11{plus minus}1.07. The consequent restrictions on extra fermion generations and an extra neutral gauge boson are discussed.
18752476
New LEP bounds on $B$ violating scalar couplings: R-parity violating supersymmetry or diquarks
We use the precision electroweak data at LEP to place bounds on B-violating Yukawa couplings, two theoretically appealing examples being provided by R-parity violating supersymmetry and diquarks. The couplings involving the third generation quarks are most severely constrained. These bounds are complementary to those obtained from low-energy processes.
14153610
Testing orbifold models of Supersymmetric Grand Unification
In a model of supersymmetric SU(5) grand unification with a spatial dimension described by the orbifold S1/(Z2 × Z'2), proton decay is naturally suppressed at all orders. This is achieved by a suitable implementation of the discrete symmetries on the brane. But baryon number violating interactions are present in this model. We propose a few possible experimental tests of this model which exploit the effect of the baryon number violating couplings on low-energy observables such as neutron–antineutron oscillations, double nucleon decay into two kaons, hadronic decay widths of the Z boson and t production cross section in Run II of the Tevatron.
16388012
Supersymmetry as a physics beyond the standard model
Here I briefly discuss why supersymmetry is considered a leading candidate of physics beyond the standard model. I also highlight the salient features of different supersymmetry breaking models. A few other symmetries, broken or intact, asscociated with any realistic supersymmetric model are also identified. This write-up is too simple-minded for an expert on supersymmetry. It is basically intended for those who are busy in other areas of high energy physics.
13112400
Can R-parity violation explain the LSND data as well?
The recent Super-Kamiokande data now admit only one type of mass hierarchy in a framework with three active and one sterile neutrino. We show that neutrino masses and mixings generated by R-parity-violating couplings, with values within their experimental upper limits, are capable of reproducing this hierarchy, explaining all neutrino data particularly after including the LSND results.
16298674
LEP- and low energy-bounds on R-parity-violating supersymmetric Yukawa couplings
Electroweak precision data at LEP are used to place bounds on some $\lambda'$-type ($L$-violating) and $\lambda''$-type ($B$-violating) $R$-parity violating supersymmetric Yukawa couplings. We consider one-loop corrections (triangles and self-energies) induced by these couplings to the $Z$-partial widths. The couplings involving the top quark induce stronger loop effects and hence are more strongly constrained than others. On the other hand, information on $D$- and $\tau$-decays are used to constrain some of the $\lambda'$-type couplings which are complementary to the ones constrained from LEP. Among the bounds we have derived, many are new from a phenomenological view-point.
45361532
Hadron masses at finite density from the Zimanyi-Moskowski model.