20,700 research outputs found
Renormalization of 2PI resummation: a renormalization scheme approach
A practical method is suggested for performing renormalized 2PI resummation
at finite temperature using specific momentum dependent renormalization
schemes. In this method there is no need to solve Bethe-Salpeter equations for
2PI resummation. We examine the consistency of such schemes in the paper. The
proposed method is used to perform a two-loop renormalized 2PI resummation in
the finite temperature Phi^4 model.Comment: 14 pages revtex, 8 figure
CP violation at one loop in the polarization-independent chargino production in e+e- collisions
Recently Osland and Vereshagin noticed, based on sample calculations of some
box diagrams, that in unpolarised e+e- collisions CP-odd effects in the
non-diagonal chargino-pair production process are generated at one-loop. Here
we perform a full one-loop analysis of these effects and point out that in some
cases the neglected vertex and self-energy contributions may play a dominant
role. We also show that CP asymmetries in chargino production are sensitive not
only to the phase of mu parameter in the chargino sector but also to the phase
of stop trilinear coupling A_t.Comment: 14 pages, 5 figure
‘Tenderstem’ Broccoli for Export Markets: an Analysis Study on the AgroFood Company
Decision case, horticulture, agriculture economics, broccoli production, protected vegetable production, Agricultural Finance, Crop Production/Industries, Production Economics,
Two-loop SUSY QCD corrections to the chargino masses in the MSSM
We have calculated the two-loop strong interaction corrections to the
chargino pole masses in the DRbar'-scheme in the Minimal Supersymmetric
Standard Model (MSSM) with complex parameters. We have performed a detailed
numerical analysis for a particular point in the parameter space and found
corrections of a few tenths of a percent. We provide a computer program which
calculates chargino and neutralino masses with complex parameters including the
one-loop corrections and all two-loop SQCD effects.Comment: 12 pages, 11 figures, references modified, clarifications adde
Fidelity Bounds for Device-Independent Advantage Distillation
It is known that advantage distillation (that is, information reconciliation
using two-way communication) improves noise tolerances for quantum key
distribution (QKD) setups. Two-way communication is hence also of interest in
the device-independent case, where noise tolerance bounds for one-way error
correction are currently too low to be experimentally feasible. Existing
security proofs for the device-independent repetition-code protocol (the most
prominent form of advantage distillation) rely on fidelity-related security
conditions, but previous bounds on the fidelity were not tight. We improve on
those results by developing an algorithm that returns arbitrarily tight lower
bounds on the fidelity. Our results give new insight on how strong the
fidelity-related security conditions are, and could also be used to compute
some lower bounds on one-way protocol keyrates. Finally, we conjecture a
necessary security condition for the protocol studied in this work, that
naturally complements the existing sufficient conditions.Comment: 14 pages, 3 figures. Main changes: New observations regarding the
pretty-good fidelity and quantum Chernoff bound. Modification/Generalization
of Conjectured Necessary Conditio
On q-Gaussians and Exchangeability
The q-Gaussians are discussed from the point of view of variance mixtures of
normals and exchangeability. For each q< 3, there is a q-Gaussian distribution
that maximizes the Tsallis entropy under suitable constraints. This paper shows
that q-Gaussian random variables can be represented as variance mixtures of
normals. These variance mixtures of normals are the attractors in central limit
theorems for sequences of exchangeable random variables; thereby, providing a
possible model that has been extensively studied in probability theory. The
formulation provided has the additional advantage of yielding process versions
which are naturally q-Brownian motions. Explicit mixing distributions for
q-Gaussians should facilitate applications to areas such as option pricing. The
model might provide insight into the study of superstatistics.Comment: 14 page
Model checking ω-regular properties for quantum Markov chains
© Yuan Feng, Ernst Moritz Hahn, Andrea Turrini, and Shenggang Ying. Quantum Markov chains are an extension of classical Markov chains which are labelled with super-operators rather than probabilities. They allow to faithfully represent quantum programs and quantum protocols. In this paper, we investigate model checking !-regular properties, a very general class of properties (including, e.g., LTL properties) of interest, against this model. For classical Markov chains, such properties are usually checked by building the product of the model with a language automaton. Subsequent analysis is then performed on this product. When doing so, one takes into account its graph structure, and for instance performs different analyses per bottom strongly connected component (BSCC). Unfortunately, for quantum Markov chains such an approach does not work directly, because super-operators behave differently from probabilities. To overcome this problem, we transform the product quantum Markov chain into a single super-operator, which induces a decomposition of the state space (the tensor product of classical state space and the quantum one) into a family of BSCC subspaces. Interestingly, we show that this BSCC decomposition provides a solution to the issue of model checking ω-regular properties for quantum Markov chains
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