Seesaw and noncommutative geometry
The 1-loop corrections to the seesaw mechanism in the noncommutative standard model are computed. Other consequences of the Lorentzian signature in the inner space are summarised.
hep-th↗
arXiv subjects
J. -H. Jureit
Publications and source records attributed to J. -H. Jureit.
Quasi-quantum groups from Kalb-Ramond fields and magnetic amplitudes for strings on orbifolds
We present the general form of the operators that lift the group action on the twisted sectors of a bosonic string on an orbifold ${\cal M}/G$, in the presence of a Kalb-Ramond field strength $H$. These operators turn out to generate the quasi-quantum group $D_ω[G]$, introduced in the context of orbifold conformal field theory by R. Dijkgraaf, V. Pasquier and P. Roche. The 3-cocycle $ω$ entering in the definition of $D_ω[G]$ is related to $H$ by a series of cohomological equations in a tricomplex combining de Rham, Cech and group coboundaries. We construct magnetic amplitudes for the twisted sectors and show that $ω=1$ arises as a consistency condition for the orbifold theory. Finally, we recover discrete torsion as an ambiguity in the lift of the group action to twisted sectors, in accordance with previous results presented by E. Sharpe.
hep-th↗
Quasi-quantum groups from strings
Motivated by string theory on the orbifold ${\cal M}/G$ in presence of a Kalb-Ramond field strength $H$, we define the operators that lift the group action to the twisted sectors. These operators turn out to generate the quasi-quantum group $D_ω[G]$, introduced in the context of conformal field theory by R. Dijkgraaf, V. Pasquier and P. Roche, with $ω$ a 3-cocycle determined by a series of cohomological equations in a tricomplex combining de Rham, uCech and group cohomologies. We further illustrate some properties of the quasi-quantum group from a string theoretical point of view.
hep-th↗
Quantum field theory on projective modules
We propose a general formulation of perturbative quantum field theory on (finitely generated) projective modules over noncommutative algebras. This is the analogue of scalar field theories with non-trivial topology in the noncommutative realm. We treat in detail the case of Heisenberg modules over noncommutative tori and show how these models can be understood as large rectangular pxq matrix models, in the limit p/q->theta, where theta is a possibly irrational number. We find out that the modele is highly sensitive to the number-theoretical aspect of theta and suffers from an UV/IR-mixing. We give a way to cure the entanglement and prove one-loop renormalizability.
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Cosmic UHE Neutrino Signatures
Utilizing the unique and reliable ultrasmall--$x$ predictions of the dynamical (radiative) parton model, nominal event rates and their detailed energy dependence caused by a variety of cosmic UHE neutrino fluxes are calculated and analyzed. In addition, maximal Regge--model inspired small--$x$ structure functions are employed for obtaining optimal rates which do not necessarily require `new' physics interpretations. Upward $μ^+ +μ^-$ event rates are estimated by taking into account total and nadir--angle dependent regeneration effects due to neutral current interactions. For exploring extragalactic neutrino sources at highest energies (\raisebox{-0.1cm}{$\stackrel{>}{\sim}$} $10^8$ GeV) with modern (future) ground--level telescopes, we analyze horizontal air shower event rates and shower events caused by Earth--skimming tau--neutrinos, in particular their detailed shower-- and cosmic neutrino--energy dependence. As an illustration of `new physics' implications we estimate the relevant horizontal air shower event rates due to spin--2 Kaluza--Klein `graviton' exchanges in neutral current neutrino--quark and neutrino--gluon interactions at low TeV--scales.
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