NonzeroZ→γγdecays in the renormalizable gauge sector of the noncommutative standard model

Abstract

In this work we propose the Z → γγ decay as a process strictly forbidden in the standard model, suitable for the search of noncommutativity of coordinates at very short distances. We computed the Z → γγ partial width in the framework of the recently proposed one-loop renormalizable gauge sector of the noncommutative standard model. New experimental possibilities at LHC are analyzed and a firm bound to the scale of noncommutativity parameter is set around 1 TeV.

Quantum gravity, field theory and signatures of noncommutative spacetime

“…Other Lorentz-violating processes, which have been studied in the context of noncommutative extensions of the standard model, include Z 0 → γ γ [104,105] and decays of quarkonia [106]. Violations of causality can be most readily observed by looking at signatures for spin-statistics violation extracted from atomic transitions in quantum electrodynamics.…”

Holographic quark gluon plasma with flavor

“…The frequency of this precession depends on the strength of the external field as well as on the gyromagnetic moment taking into account quantum effects and is called Larmor frequency. Let us choose the geometry with the magnetic Our situation for the flavor field fluctuations is completely analogous except for the fact that our precession takes place in the internal flavor space rather than in space-time 19 . We have the torque on the flavor field fluctuations inside flavor space 128) where the components correspond to the three flavor directions {T 1 + iT 2 , T 1 − iT 2 , T 3 } in the case of SU(2)-flavor.…”

“…Starting from the general action 19) we now consider field strength tensorŝ 20) with the Pauli matrices σ a and given by equation (5.1). The factor ̺ 2 H /(2πα ′ ) is due to the introduction of dimensionless fields as described below (4.135).…”

“…Some further phenomenologically studied extensions contain extra-dimensions [14, for a review], the non-commutative standard model with non-commuting space-time coordinates [15] (recent progress may be found in [16,17,18,19]) and the addition of an unparticle sector governed by conformal symmetry [20] which thus is closely related to the conformal theories we will review in section 2.2.1. But the most developed and consistent theory known to incorporate gravity in the same conceptual way as all other forces is string theory (note, that loop quantum gravity [21, for a recent review] has the same goal).…”

Noncommutative electrodynamics from $$SO(2,3)_\star $$ S O ( 2 , 3 ) ⋆

“…Then we have θ = . According to [35] the scale of noncommutativity NC 1.0 TeV, and so the lower bound for θ would be of order 10 −37 m 2 . We will take NC 10 TeV.…”