arXiv subjects

B. A. Qureshi

Publications and source records attributed to B. A. Qureshi.

7 recordsLinked to original sources

arXiv2010

Poincare' Quasi-Hopf Symmetry and Non-Associative Spacetime Algebra from Twisted Gauge Theories

In previous work, starting from the Moyal plane, we formulated interacting theories of matter and gauge fields with only the former fields twisted. In this approach, gauge theories, including the standard model, can be formulated without new gauge degrees of freedom. We show their underlying symmetry algebra to be Poincaré quasi-Hopf . The associated spacetime algebra is hence non-associative.

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arXiv2009

QED on the Groenewold Moyal Plane

We investigate a version of noncommutative QED where the interaction term, although natural, breaks the spin-statistics connection. We calculate $e^- + e^- -> e^- + e^-$ and $γ+ e^- -> γ+ e^-$ cross-sections in the tree approximation and explicitly display their dependence on theta^{μν}. Remarkably the zero of the elastic $e^- + e^- -> e^- + e^-$ cross-section at 90-degrees in the center-of-mass system, which is due to Pauli principle, is shifted away as a function of theta^{μν} and energy.

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arXiv2007

Twisted Gauge and Gravity Theories on the Groenewold-Moyal Plane

Recent work [hep-th/0504183,hep-th/0508002] indicates an approach to the formulation of diffeomorphism invariant quantum field theories (qft's) on the Groenewold-Moyal (GM) plane. In this approach to the qft's, statistics gets twisted and the S-matrix in the non-gauge qft's becomes independent of the noncommutativity parameter theta^{μν}. Here we show that the noncommutative algebra has a commutative spacetime algebra as a substructure: the Poincare, diffeomorphism and gauge groups are based on this algebra in the twisted approach as is known already from the earlier work of [hep-th/0510059]. It is natural to base covariant derivatives for gauge and gravity fields as well on this algebra. Such an approach will in particular introduce no additional gauge fields as compared to the commutative case and also enable us to treat any gauge group (and not just U(N)). Then classical gravity and gauge sectors are the same as those for θ^{μν}=0, but their interactions with matter fields are sensitive to theta^{μν}. We construct quantum noncommutative gauge theories (for arbitrary gauge groups) by requiring consistency of twisted statistics and gauge invariance. In a subsequent paper (whose results are summarized here), the locality and Lorentz invariance properties of the S-matrices of these theories will be analyzed, and new non-trivial effects coming from noncommutativity will be elaborated. This paper contains further developments of [hep-th/0608138] and a new formulation based on its approach.

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arXiv2007

S-Matrix on the Moyal Plane: Locality versus Lorentz Invariance

Twisted quantum field theories on the Groenewold-Moyal plane are known to be non-local. Despite this non-locality, it is possible to define a generalized notion of causality. We show that interacting quantum field theories that involve only couplings between matter fields, or between matter fields and minimally coupled U(1) gauge fields are causal in this sense. On the other hand, interactions between matter fields and non-abelian gauge fields violate this generalized causality. We derive the modified Feynman rules emergent from these features. They imply that interactions of matter with non-abelian gauge fields are not Lorentz- and CPT-invariant.

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arXiv2007

Twisted Poincaré Invariant Quantum Field Theories

It is by now well known that the Poincaré group acts on the Moyal plane with a twisted coproduct. Poincaré invariant classical field theories can be formulated for this twisted coproduct. In this paper we systematically study such a twisted Poincaré action in quantum theories on the Moyal plane. We develop quantum field theories invariant under the twisted action from the representations of the Poincaré group, ensuring also the invariance of the S-matrix under the twisted action of the group . A significant new contribution here is the construction of the Poincaré generators using quantum fields.

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arXiv2007

Twisted Supersymmetry, Fermion-Boson Mixing and Removal of UV-IR Mixing

Exact supersymmetry can be maintained on nonanticommutative superspace with a twisted coproduct on the supergroup.We show that the usual exchange statistics for the superfields is not compatible with the twisted action of the superpoincare group and find a statistics which is consistent with the twisted coproduct and imply interesting phenomena such as mixing of fermions and bosons under particle exchange.We also show that with the new statistics, the $S$-matrix becomes completely independent of the deformation parameter.

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arXiv2006

Statistics and UV-IR Mixing with Twisted Poincare Invariance

We elaborate on the role of quantum statistics in twisted Poincare invariant theories. It is shown that, in order to have twisted Poincare group as the symmetry of a quantum theory, statistics must be twisted. It is also confirmed that the removal of UV-IR mixing (in the absence of gauge fields) in such theories is a natural consequence.

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