arXiv subjects

Jiangyang You

Publications and source records attributed to Jiangyang You.

25 records · Page 2Linked to original sources

arXiv2015

Photon self-interaction on deformed spacetime

A novel nonlocal four-photon interaction on the deformed spacetime is derived and studied in the three selected models (I, II, III). The first two models (I, II) are obtained via two distinct second-order $θ$-exact Seiberg-Witten maps of the noncommutative U(1) gauge field strength on Moyal space. The third one (III), inspired by the manifestly gauge invariant structures emerging in the first two, due to the model generality has been constructed with a different set of freedom parameters. The physical relevancy of all models is analyzed by evaluating the four-photon-tadpole diagram, which, when combined with the bubble graph, enables us to fully consider all contributions to the one-loop photon polarization tensor. For an arbitrary noncommutative matrix theta^μν, the full quadratic IR divergence cancellation in the one-loop photon two-point function is obtained with particular combinations of Seiberg-Witten map/gauge-symmetry freedom parameters in models I and II. Finally, our model III enables complete elimination of all pathological terms in the photon polarization tensor at one-loop order if a special value for the theta matrix is chosen.

hep-th↗

arXiv2015

The theta-exact Seiberg-Witten maps at the e3 order

We study wo distinct theta-exact Seiberg-Witten (SW) map expansions, (I) and (II) respectively, up to the e3 order for the gauge parameter, gauge field and the gauge field strengths of the noncommutative U*(1) gauge theory on the Moyal space. We derive explicitly the closed form expression for the SW map ambiguity between the two and observe the emergence of several new totally commutative generalized star products. We also identify the additional gauge freedoms within each of the e3 order field strength expansions and define corresponding sets of deformation/ratio/weight parameters, (kappa,kappa_i) and (kappa,kappa'_i), for these two SW maps respectively.

hep-th↗

arXiv2014

Two-Point Functions on Deformed Spacetime

We present a review of the one-loop photon ($Π$) and neutrino ($Σ$) two-point functions in a covariant and deformed $\rm U(1)$ gauge-theory on the 4-dimensional noncommutative spaces, determined by a constant antisymmetric tensor $θ^{μν}$, and by a parameter-space $(κ_f,κ_g)$, respectively. For the general fermion-photon $S_f(κ_f)$ and photon self-interaction $S_g(κ_g)$ the closed form results reveal two-point functions with all kind of pathological terms: the UV divergence, the quadratic UV/IR mixing terms as well as a logarithmic IR divergent term of the type $\ln(μ^2(θp)^2)$. In addition, the photon-loop produces new tensor structures satisfying transversality condition by themselves. We show that the photon two-point function in the 4-dimensional Euclidean spacetime can be reduced to two finite terms by imposing a specific full rank of $θ^{μν}$ and setting deformation parameters $(κ_f,κ_g)=(0,3)$. In this case the neutrino two-point function vanishes. Thus for a specific point $(0,3)$ in the parameter-space $(κ_f,κ_g)$, a covariant $θ$-exact approach is able to produce a divergence-free result for the one-loop quantum corrections, having also both well-defined commutative limit and point-like limit of an extended object.

hep-th↗

arXiv2014

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

The triple neutral gauge boson and direct U(1)_Y-neutrino interactions, being absent in ordinary field theory, can arise quite naturally in noncommutative gauge field theories. Using non-perturbative methods and a Seiberg-Witten map based covariant approach to noncommutative gauge theory, we have found theta-exact expressions for both interactions, thereby eliminating previous restrictions to low-energy phenomena. In particular we obtain for the first time the covariant, theta-exact, triple neutral gauge boson interactions within the noncommutative Standard Model gauge sector including an additional gauge-field deformation freedom. Finally we discuss implications for Z->2gamma and Z->neutrino-pair decays, and show that our results behave quite reasonably throughout all interaction energy scales.

hep-ph↗

arXiv2012

Yukawa couplings and seesaw neutrino masses in noncommutative gauge theory

We consider Yukawa couplings in a theta-exact approach to noncommutative gauge field theory and show that both Dirac and singlet Majorana neutrino mass terms can be consistently accommodated. This shows that in fact the whole neutrino-mass extended standard model on noncommutative spacetime can the formulated in the new nonperturbative (in theta) approach which eliminates the previous restriction of Seiberg-Witten map based theories to low-energy phenomena. Spacetime noncommutativity induced couplings between neutrinos and photons as well as Z-bosons appear quite naturally in the model. We derive relevant Feynman rules for the type I seesaw mechanism.

hep-th↗

arXiv2008

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 θare 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.

hep-th↗

arXiv2008

Macroscopic Screening of Coulomb Potentials From UV/IR-Mixing

We compute the static potential in a non-commutative theory including a term due to UV/IR-mixing. As a result, the potential decays exponentially fast with distance rather than like a power law Coulomb type potential due to the exchange of massless particles. This shows that when quantum effects are taken into account the introduction of non-commutativity not only modifies physics at short distances but has dramatic macroscopic consequences as well. As a result, we give a lower bound on the scale of non-commutativity (if present at all) to be compatible with observations.

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