5,370 research outputs found
The Glashow resonance as a discriminator of UHE cosmic neutrinos originating from p-gamma and p-p collisions
We re-examine the interesting possibility of utilizing the Glashow resonance
(GR) channel nu_ebar + e^- to W^- to anything to discriminate between the UHE
cosmic neutrinos originating from p-gamma and pp collisions in an optically
thin source of cosmic rays. We propose a general parametrization of the initial
neutrino flavor composition by allowing the ratios Phi^{p gamma}_{pi^-}/Phi^{p
gamma}_{pi^+} and Phi^{pp}_{pi^-}/Phi^{pp}_{pi^+} to slightly deviate from
their conventional values. A relationship between the typical source parameter
kappa = (Phi^{p gamma}_{pi^+} + Phi^{p gamma}_{pi^-})/(Phi^{pp}_{pi^+} +
Phi^{pp}_{pi^-} + Phi^{p gamma}_{pi^+} + Phi^{p gamma}_{pi^-}) and the working
observable of the GR R_0 = Phi^T_{nu_ebar}/ (Phi^T_{nu_mu} + Phi^T_{nu_mu}) at
a neutrino telescope is derived, and the numerical dependence of R_0 on kappa
is illustrated by taking account of the latest experimental data on three
neutrino mixing angles. It is shown that a measurement of R_0 is in principle
possible to identify the pure p-gamma interaction (kappa =1), the pure pp
interaction (kappa =0) or a mixture of both of them (0 < kappa < 1) at a given
source of UHE cosmic neutrinos. The event rate of the GR signal against the
background is also estimated.Comment: 13 pages, 6 figures, final version to appear in Phys. Rev.
Analysis of the vertex with the light-cone QCD sum rules
In this article, we analyze the vertex with the light-cone QCD
sum rules. The strong coupling constant is an important
parameter in evaluating the charmonium absorption cross sections in searching
for the quark-gluon plasmas. Our numerical value for the is
consistent with the prediction of the effective SU(4) symmetry and vector meson
dominance theory.Comment: 6 pages, 1 figure, revised versio
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Progressing problems from requirements to specifications in problem frames
One of the problems with current practice in software development is that often customer requirements are not well captured, understood and analysed, and there is no clear traceable path from customer requirements to software specifications. This often leads to a mismatch between what the customer needs and what the software developer understands the customer needs.
In addition to capturing, understanding and analysing requirements, requirements engineering (RE) aims to provide methods to allow software development practitioners to derive software specifications from requirements. Although work exists towards this aim, the systematic derivation of specifications from requirements is still an open problem.
This thesis provides practical techniques to implement the idea of problem progression as the basis for transforming requirements into specifications. The techniques allow us to progress a software problem towards identifying its solution by carefully investigating the problem context and re-expressing the requirement statement until a specification is reached. We develop two classes of progression techniques, one formal, based on Hoare’s Communicating Sequential Processes (CSP), and one semi-formal, based on a notion of causality between events. The case studies in this thesis provide some validation for the techniques we have developed
The T2K Indication of Relatively Large theta_13 and a Natural Perturbation to the Democratic Neutrino Mixing Pattern
The T2K Collaboration has recently reported a remarkable indication of the
\nu_\mu -> \nu_e oscillation which is consistent with a relatively large value
of \theta_{13} in the three-flavor neutrino mixing scheme. We show that it is
possible to account for such a result of \theta_{13} by introducing a natural
perturbation to the democratic neutrino mixing pattern, without or with CP
violation. A testable correlation between \theta_{13} and \theta_{23} is
predicted in this ansatz. We also discuss the Wolfenstein-like parametrization
of neutrino mixing, and comment on other possibilities of generating
sufficiently large \theta_{13} at the electroweak scale.Comment: RevTeX 8 page
Analysis of the X(1576) as a tetraquark state with the QCD sum rules
In this letter, we take the point of view that the X(1576) be tetraquark
state which consists of a scalar-diquark and an anti-scalar-diquark in relative
-wave, and calculate its mass in the framework of the QCD sum rules
approach. The numerical value of the mass is
consistent with the experimental data, there may be some tetraquark component
in the vector meson X(1576).Comment: 6 pages, 1 figure, second version, typos correcte
Experimental tests on the lifetime Asymmetry
The experimental test problem of the left-right polarization-dependent
lifetime asymmetry is discussed. It shows that the existing experiments cannot
demonstrate the lifetime asymmetry to be right or wrong after analyzing the
measurements on the neutron, the muon and the tau lifetime, as well as the
experiment. However, It is pointed out emphatically that the SLD and the
E158 experiments, the measurements of the left-right integrated cross section
asymmetry in boson production by collisions and by
electron-electron M{\o}ller scattering, can indirectly demonstrate the lifetime
asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose
some possible experiments on the decays of polarized muons. The precise
measurement of the lifetime asymmetry could have important significance for
building a muon collider, also in cosmology and astrophysics. It would provide
a sensitive test of the standard model in particle physics and allow for
exploration of the possible interactions.Comment: 11 pages, 1 figur
Detecting a set of entanglement measures in an unknown tripartite quantum state by local operations and classical communication
We propose a more general method for detecting a set of entanglement
measures, i.e. negativities, in an \emph{arbitrary} tripartite quantum state by
local operations and classical communication. To accomplish the detection task
using this method, three observers, Alice, Bob and Charlie, do not need to
perform the partial transposition maps by the structural physical
approximation; instead, they are only required to collectively measure some
functions via three local networks supplemented by a classical communication.
With these functions, they are able to determine the set of negativities
related to the tripartite quantum state.Comment: 16 pages, 2 figures, revte
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