40,649 research outputs found
Quark Mass Matrices in the A_4 Model
If the standard model of quark interactions is supplemented by a discrete A_4
symmetry (which may be relevant for the lepton sector), the spontaneous
breaking of the electroweak gauge symmetry allows arbitrary quark masses, but
all mixing angles are predicted to be zero. A pattern of the explicit breaking
of A_4 is proposed, which results in a realistic charged-current mixing matrix.Comment: 6 pages, no figur
Analysis of decays in the perturbative QCD approach
Within the framework of perturbative QCD approach, we study the charmless
two-body decays . Using the decays constants
and the light-cone distribution amplitudes for these mesons derived from the
QCD sum rule method, we find the following results: (a) Our predictions for the
branching ratios are consistent well with the QCDF results within errors, but
much larger than the naive factorization approach calculation values. (b) We
predict that the anomalous polarizations occurring in the decays also happen in the decays , while do not happen in
the decays . Here the contributions from the annihilation diagrams
play an important role to explain the lager transverse polarizations in the
decays , while they are not sensitive to the polarizations in
decays . (c) Our predictions for the direct CP-asymmetries agree
well with the QCDF results within errors. The decays have larger direct CP-asymmetries, which
could be measured by the present LHCb experiments.Comment: 12pages, 1figures. arXiv admin note: substantial text overlap with
arXiv:1203.5913, arXiv:1203.591
Non-universal gauge boson and the spin correlation of top quark pair production at colliders
In the off-diagonal basis, we discuss the contributions of the non-universal
gauge boson predicted by the topcolor-assisted technicolor () model
to the spin configurations and the spin correlation observable of the top quark
pair production via the process . Our numerical results
show that the production cross sections for the like-spin states, which vanish
in the standard model, can be significantly large as .
With reasonable values of the mass and the coupling parameter
,
exchange can generate large corrections to the spin correlation
observable.Comment: 16 pages, 5 figure
Heavy Quarkonium States with the Holographic Potential
The quarkonium states in a quark-gluon plasma is examined with the heavy
quark potential implied by the holographic principle. Both the vanila
AdS-Schwarzschild metric and the one with an infrared cutoff are considered.
The dissociation temperature is calculated by solving the Schr\"o dinger
equation of the potential model. In the case of the AdS-Schwarzschild metric
with a IR cutoff, the dissociation temperatures for and
with the U-ansatz of the potential are found to agree with the lattice results
within a factor of two.Comment: 9 pages with 2 figues in Revte
On the frequency of permutations containing a long cycle
A general explicit upper bound is obtained for the proportion of
elements of order dividing , where for some constant ,
in the finite symmetric group . This is used to find lower bounds for the
conditional probabilities that an element of or contains an
-cycle, given that it satisfies an equation of the form where
. For example, the conditional probability that an element is an
-cycle, given that , is always greater than 2/7, and is greater than
1/2 if does not divide 24. Our results improve estimates of these
conditional probabilities in earlier work of the authors with Beals,
Leedham-Green and Seress, and have applications for analysing black-box
recognition algorithms for the finite symmetric and alternating groups
Neurocognitive impairment is associated with lower health literacy among persons living with HIV infection.
This study sought to determine the effects of HIV-associated neurocognitive disorders (HAND) on health literacy, which encompasses the ability to access, understand, appraise, and apply health-related information. Participants included 56 HIV seropositive individuals, 24 of whom met Frascati criteria for HAND, and 24 seronegative subjects who were comparable on age, education, ethnicity, and oral word reading. Each participant was administered a brief battery of well-validated measures of health literacy, including the Expanded Numeracy Scale (ENS), Newest Vital Sign (NVS), Rapid Estimate of Adult Literacy in Medicine (REALM), and Brief Health Literacy Screen (BHLS). Results revealed significant omnibus differences on the ENS and NVS, which were driven by poorer performance in the HAND group. There were no significant differences on the REALM or the BHLS by HAND status. Among individuals with HAND, lower scores on the NVS were associated with greater severity of neurocognitive dysfunction (e.g., working memory and verbal fluency) and self-reported dependence in activities of daily living. These preliminary findings suggest that HAND hinders both fundamental (i.e., basic knowledge, such as numeracy) and critical (i.e., comprehension and application of healthcare information) health literacy capacities, and therefore may be an important factor in the prevalence of health illiteracy. Health literacy-focused intervention may play an important role in the treatment and health trajectories among persons living with HIV infection
Strategic Outsourcing: Evidence from the British Companies
Outsourcing has become an increasingly popular option for many organisations. But they vary in terms of activities being outsourced, reasons for and benefits from outsourcing, and how the decision was made. This article presents an empirical research on fourteen companies. It found out, a) in most cases it was the ‘peripheral’ support activity being outsourced with cost reduction as the primary driver; b) outsourcing decision was being made early in the process without active involvement of the in-house provider; and c) there were problems in supplier selection and management. The research identified pre-outsourcing decision process and post-outsourcing management as the two key areas that gave cause for concern, and offered recommendations for improvement
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