4,860 research outputs found
Twisted Poincar\'e Invariant Quantum Field Theories
It is by now well known that the Poincar\'e group acts on the Moyal plane
with a twisted coproduct. Poincar\'e invariant classical field theories can be
formulated for this twisted coproduct. In this paper we systematically study
such a twisted Poincar\'e action in quantum theories on the Moyal plane. We
develop quantum field theories invariant under the twisted action from the
representations of the Poincar\'e 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 Poincar\'e generators using quantum fields.Comment: 17 pages, JHEP styl
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.Comment: 15 pages, LaTeX, 1 figur
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^{\mu\nu}. 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 \theta^{\mu \nu}=0, but their interactions with matter
fields are sensitive to theta^{\mu \nu}. 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.Comment: 17 pages, LaTeX, 1 figur
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.Comment: 13 pages, LaTeX; typos correcte
Energy-Aware Cloud Management through Progressive SLA Specification
Novel energy-aware cloud management methods dynamically reallocate
computation across geographically distributed data centers to leverage regional
electricity price and temperature differences. As a result, a managed VM may
suffer occasional downtimes. Current cloud providers only offer high
availability VMs, without enough flexibility to apply such energy-aware
management. In this paper we show how to analyse past traces of dynamic cloud
management actions based on electricity prices and temperatures to estimate VM
availability and price values. We propose a novel SLA specification approach
for offering VMs with different availability and price values guaranteed over
multiple SLAs to enable flexible energy-aware cloud management. We determine
the optimal number of such SLAs as well as their availability and price
guaranteed values. We evaluate our approach in a user SLA selection simulation
using Wikipedia and Grid'5000 workloads. The results show higher customer
conversion and 39% average energy savings per VM.Comment: 14 pages, conferenc
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