Jiangyang You

UV/IR mixing in noncommutative QED defined by Seiberg-Witten map

Noncommutative gauge theories defined via Seiberg-Witten map have desirable properties that theories defined directly in terms of noncommutative fields lack, covariance and unrestricted choice of gauge group and charge being among them, but nonperturbative results in the deformation parameter θ are hard to obtain. In this article we use a θ-exact approach to study UV/IR mixing in a noncommutative quantum electrodynamics (NCQED) model defined via Seiberg-Witten map. The fermion contribution of the one loop correction to the photon propagator is computed and it is found that it gives the same UV/IR mixing term as a NCQED model without Seiberg-Witten map.

Photon-neutrino interaction in θ -exact covariant noncommutative field theory

Photon-neutrino interactions arise quite naturally in noncommutative field theories. Such couplings are absent in ordinary field theory and imply experimental lower bounds on the energy scale

On UV/IR mixing in noncommutative gauge field theories

{\ensuremath{\Lambda}}_{\mathrm{NC}}\ensuremath{\sim}|\ensuremath{\theta}{|}^{\ensuremath{-}2}

Neutrino propagation in noncommutative spacetimes

of noncommutativity. Using nonperturbative methods and a Seiberg-Witten map based covariant approach to noncommutative gauge theory, we obtain

Yukawa couplings and seesaw neutrino masses in noncommutative gauge theory

\ensuremath{\theta}

Macroscopic Screening of Coulomb Potentials From UV/IR-Mixing

-exact expressions for the interactions, thereby eliminating previous restrictions to low-energy phenomena. We discuss implications for plasmon decay, neutrino charge radii, big bang nucleosynthesis, and ultrahigh energy cosmic rays. Our results behave reasonably throughout all interaction energy scales, thus facilitating further phenomenological applications.

Self-energies on deformed spacetimes

A bstractIn formulating gauge field theories on noncommutative (NC) spaces it is suggested that particles carrying gauge invariant quantities should not be viewed as pointlike, but rather as extended objects whose sizes grow linearly with their momenta. This and other generic properties deriving from the nonlocal character of interactions (showing thus unambiguously their quantum-gravity origin) lead to a specific form of UV/IR mixing as well as to a pathological behavior at the quantum level when the noncommutativity parameter θ is set to be arbitrarily small. In spite of previous suggestions that in a NC gauge theory based on the θ-expanded Seiberg-Witten (SW) maps UV/IR mixing effects may be under control, a fairly recent study of photon self-energy within a SW θ-exact approach has shown that UV/IR mixing is still present. We study the self-energy contribution for neutral massless fermions in the θ-exact approach of NC QED, and show by explicit calculation that all but one divergence can be eliminated for a generic choice of the noncommutativity parameter θ. The remaining divergence is linked to the pointlike limit of an extended object.In formulating gauge field theories on noncommutative (NC) spaces it is suggested that particles carrying gauge invariant quantities should not be viewed as pointlike, but rather as extended objects whose sizes grow linearly with their momenta. This and other generic properties deriving from the nonlocal character of interactions (showing thus unambiguously their quantum-gravity origin) lead to a specific form of UV/IR mixing as well as to a pathological behavior at the quantum level when the noncommutativity parameter θ is set to be arbitrarily small. In spite of previous suggestions that in a NC gauge theory based on the θ-expanded Seiberg-Witten (SW) maps UV/IR mixing effects may be under control, a fairly recent study of photon self-energy within a SW θ-exact approach has shown that UV/IR mixing is still present. We study the self-energy contribution for neutral massless fermions in the θ-exact approach of NC QED, and show by explicit calculation that all but one divergence can be eliminated for a generic choice of the noncommutativity parameter θ. The remaining divergence is linked to the pointlike limit of an extended object.

Forbidden and invisible Z boson decays in a covariant θ-exact noncommutative standard model

A bstractOne-loop θ-exact quantum corrections to the neutrino propagator are computed in noncommutative U⋆(1) gauge-theory based on Seiberg-Witten maps. Our closed form results show that the one-loop correction contains a hard 1/ǫ UV divergence, as well as a logarithmic IR-divergent term of the type ln

Photon self-interaction on deformed spacetime

\sqrt {{{{\left( {\theta p} \right)}^{{2}}}}}

Macroscopic screening of 1/r potentials from UV/IR-mixing

, thus considerably softening the usual UV/IR mixing phenomenon. We show that both of these problematic terms vanish for a certain choice of the noncommutative parameter θ which preserves unitarity. We find non-perturbative modifications of the neutrino dispersion relations which are assymp-totically independent of the scale of noncommutativity in both the low and high energy limits and may allow superluminal propagation. Finally, we demonstrate how the prodigious freedom in Seiberg-Witten maps may be used to affect neutrino propagation in a profound way.