312 research outputs found
QCD Corrections to Radiative B Decays in the MSSM with Minimal Flavor Violation
We compute the complete supersymmetric QCD corrections to the Wilson
coefficients of the magnetic and chromomagnetic operators, relevant in the
calculation of b -> s gamma decays, in the MSSM with Minimal Flavor Violation.
We investigate the numerical impact of the new results for different choices of
the MSSM parameters and of the scale where the quark and squark mass matrices
are assumed to be aligned. We find that the corrections can be important when
the superpartners are relatively light, and that they depend sizeably on the
scale of alignment. Finally, we discuss how our calculation can be employed
when the scale of alignment is far from the weak scale.Comment: 16 pages, 5 figures; v2: version to appear in Phys. Lett.
On the NLO QCD corrections to Higgs production and decay in the MSSM
We present explicit analytic results for the two-loop top/stop/gluino
contributions to the cross section for the production of CP-even Higgs bosons
via gluon fusion in the MSSM, under the approximation of neglecting the Higgs
boson mass with respect to the masses of the particles circulating in the
loops. The results are obtained employing the low-energy theorem for Higgs
interactions adapted to the case of particle mixing. We discuss the validity of
the approximation used by computing the first-order correction in an expansion
in powers of the Higgs boson mass. We find that, for the lightest CP-even Higgs
boson, the gluino contribution is very well approximated by the result obtained
in the limit of vanishing Higgs mass. As a byproduct of our calculation, we
provide results for the two-loop QCD contributions to the photonic Higgs decay.Comment: 24 pages, 4 figures; v2 to appear in Nucl.Phys.B; v3 minor
corrections, note added in section 3.
QCD Corrections in two-Higgs-doublet extensions of the Standard Model with Minimal Flavor Violation
We present the QCD corrections to R_b and to the Delta B=1 effective
Hamiltonian in models with a second Higgs field that couples to the quarks
respecting the criterion of Minimal Flavor Violation, thus belonging either to
the (1,2)_1/2 or to the (8,2)_1/2 representation of SU(3)xSU(2)xU(1). After the
inclusion of the QCD corrections, the prediction for R_b becomes practically
insensitive to the choice of renormalization scheme for the top mass, which for
the type-I and type-II models translates in a more robust lower bound on
tan(beta). The QCD-corrected determinations of Rb and BR(B->Xs gamma) are used
to discuss the constraints on the couplings of a (colored) charged Higgs boson
to top and bottom quarks.Comment: 19 pages, 7 figures. v2: version published in Phys. Rev. D, with
additional reference and not
Two-loop QCD corrections to the MSSM Higgs masses beyond the effective-potential approximation
We compute the two-loop QCD corrections to the neutral Higgs-boson masses in
the MSSM, including the effect of non-vanishing external momenta in the
self-energies. We obtain corrections of O(alpha_t*alpha_s) and
O(alpha*alpha_s), i.e., all two-loop corrections that involve the strong gauge
coupling when the only non-vanishing Yukawa coupling is the top one. We adopt
either the DRbar renormalization scheme or a mixed OS-DRbar scheme where the
top/stop parameters are renormalized on-shell. We compare our results with
those of earlier calculations, pointing out an inconsistency in a recent result
obtained in the mixed OS-DRbar scheme. The numerical impact of the new
corrections on the prediction for the lightest-scalar mass is moderate, but
already comparable to the accuracy of the Higgs-mass measurement at the LHC.Comment: 22 pages, 5 pdf figures; v2: version to appear in EPJ
Out of Mind, Out of Sight: Unexpected Scene Elements Frequently Go Unnoticed Until Primed
Abstract The human visual system employs a sophisticated set of strategies for scanning the environment and directing attention to stimuli that can be expected given the context and a person's past experience. Although these strategies enable us to navigate a very complex physical and social environment, they can also cause highly salient, but unexpected stimuli to go completely unnoticed. To examine the generality of this phenomenon, we conducted eight studies that included 15 different experimental conditions and 1,577 participants in all. These studies revealed that a large majority of participants do not report having seen a woman in the center of an urban scene who was photographed in midair as she was committing suicide. Despite seeing the scene repeatedly, 46 % of all participants failed to report seeing a central figure and only 4.8 % reported seeing a falling person. Frequency of noticing the suicidal woman was highest for participants who read a narrative priming story that increased the extent to which she was schematically congruent with the scene. In contrast to this robust effect of inattentional blindness, a majority of participants reported seeing other peripheral objects in the visual scene that were equally difficult to detect, yet more consistent with the scene. Follow-up qualitative analyses revealed that participants reported seeing many elements that were not actually present, but which could have been expected given the overall context of the scene. Together, these findings demonstrate the robustness of inattentional blindness and highlight the specificity with which different visual primes may increase noticing behavior
Stress Measurement in Primary Care: Conceptual Issues, Barriers, Resources, and Recommendations for Study
Objective: Exposure to stressors in daily life and dysregulated stress responses are associated with increased risk for a variety of chronic mental and physical health problems, including anxiety disorders, depression, asthma, heart disease, certain cancers, and autoimmune and neurodegenerative disorders. Despite this fact, stress exposure and responses are rarely assessed in the primary care setting and infrequently targeted for disease prevention or treatment. Method: In this narrative review, we describe the primary reasons for this striking disjoint between the centrality of stress for promoting disease and how rarely it is assessed by summarizing the main conceptual, measurement, practical, and reimbursement issues that have made stress difficult to routinely measure in primary care. The following issues will be reviewed: (1) assessment of stress in primary care; (2) biobehavioral pathways linking stress and illness; (3) the value of stress measurements for improving outcomes in primary care; (4) barriers to measuring and managing stress; and (5) key research questions relevant to stress assessment and intervention in primary care. Results: Based on our synthesis, we suggest several approaches that can be pursued to advance this work, including feasibility and acceptability studies, cost-benefit studies, and clinical improvement studies. Conclusions: Although stress is recognized as a key contributor to chronic disease risk and mortality, additional research is needed to determine how and when instruments for assessing life stress might be useful in the primary care setting, and how stress-related data could be integrated into disease prevention and treatment strategies to reduce chronic disease burden and improve human health and wellbeing
Direct probes of R-parity-violating supersymmetric couplings via single-top-squark production
We study the s-channel production of a single top squark in hadron collisions
through an R-parity-violating mechanism, examining in detail the case in which
the squark decays through an R-parity-conserving process into a bottom quark, a
lepton, and missing energy. We show that the top squark can be discovered if
its mass is less than 400 GeV, or that the current bound on the size of the
R-parity-violating couplings can be reduced by up to one order of magnitude
with existing data and by two orders of magnitude at the forthcoming run II of
the Fermilab Tevatron.Comment: To appear in Phys. Rev. D; 32 pgs., 17 ps figs., uses RevTeX; 1 new
fig., slight textual clarification
On the NLO QCD corrections to the production of the heaviest neutral Higgs scalar in the MSSM
We present a calculation of the two-loop top-stop-gluino contributions to
Higgs production via gluon fusion in the MSSM. By means of an asymptotic
expansion in the heavy particle masses, we obtain explicit and compact analytic
formulae that are valid when the Higgs and the top quark are lighter than stops
and gluino, without assuming a specific hierarchy between the Higgs mass and
the top mass. Being applicable to the heaviest Higgs scalar in a significant
region of the MSSM parameter space, our results complement earlier ones
obtained with a Taylor expansion in the Higgs mass, and can be easily
implemented in computer codes to provide an efficient and accurate
determination of the Higgs production cross section.Comment: 18 pages, 4 figure
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