arXiv subjects

Tapio Salminen

Publications and source records attributed to Tapio Salminen.

4 recordsLinked to original sources

arXiv2011

Magnetic Monopoles in Noncommutative Space-Time: Second Order of Perturbation

We investigate the validity of the Dirac Quantization Condition (DQC) for magnetic monopoles in noncommutative space-time using an extension of the method used by Wu and Yang. We continue the work started in [1] where it was shown that the DQC can be kept unmodified in the first order of the perturbative expansion in the noncommutativity parameter θ. Here we include second order corrections and find that, in order to find solutions to the noncommutative Maxwell's equations described by the $U_\star(1)$ group, the DQC needs to be modified by perturbative corrections that introduce a dependence on space-time points. Thus the DQC fails to be a topological property of noncommutative space-time. We comment on the possible origin of this difference.

hep-th↗

arXiv2011

Noncommutative Time in Quantum Field Theory

We analyze, starting from first principles, the quantization of field theories, in order to find out to which problems a noncommutative time would possibly lead. We examine the problem in the interaction picture (Tomonaga-Schwinger equation), the Heisenberg picture (Yang-Feldman-Källén equation) and the path integral approach. They all indicate inconsistency when time is taken as a noncommutative coordinate. The causality issue appears as the key aspect, while the unitarity problem is subsidiary. These results are consistent with string theory, which does not admit a time-space noncommutative quantum field theory as its low-energy limit, with the exception of light-like noncommutativity.

hep-th↗

arXiv2011

Magnetic Monopole in Noncommutative Space-Time and Wu-Yang Singularity-Free Gauge Transformations

We investigate the validity of the Dirac Quantization Condition (DQC) for magnetic monopoles in noncommutative space-time. We use an approach which is based on an extension of the method introduced by Wu and Yang. To study the effects of noncommutativity of space-time, we consider the gauge transformations of $U_\star(1)$ gauge fields and use the corresponding deformed Maxwell's equations. Using a perturbation expansion in the noncommutativity parameter $θ$, we show that the DQC remains unmodified up to the first order in the expansion parameter. The result is obtained for a class of noncommutative source terms, which reduce to the Dirac delta function in the commutative limit.

hep-th↗

arXiv2008

Search for Higgs Bosons in SUSY Cascades in CMS and Dark Matter with Non-universal Gaugino Masses

In grand unified theories (GUT), non-universal boundary conditions for the gaugino masses may arise at the unification scale, and affect the observability of the neutral MSSM Higgs bosons (h/H/A) at the LHC. The implications of such non-universal gaugino masses are investigated for the Higgs boson production in the SUSY cascade decay chain gluino --> squark quark, squark --> neutralino_2 quark, neutralino_2 --> neutralino_1 h/H/A, h/H/A --> b b-bar produced in pp interactions. In the singlet representation with universal gaugino masses only the light Higgs boson can be produced in this cascade with the parameter region of interest for us, while with non-universal gaugino masses heavy neutral MSSM Higgs boson production may dominate. The allowed parameter space in the light of the WMAP constraints on the cold dark matter relic density is investigated in the above scenarios for gaugino mass parameters. We also demonstrate that combination of representations can give the required amount of dark matter in any point of the parameter space. In the non-universal case we show that heavy Higgs bosons can be detected in the studied cascade in parameter regions with the WMAP preferred neutralino relic density.

hep-ph↗