21 research outputs found

    Simultaneous decoupling of bottom and charm quarks

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    We compute the decoupling relations for the strong coupling, the light quark masses, the gauge-fixing parameter, and the light fields in QCD with heavy charm and bottom quarks to three-loop accuracy taking into account the exact dependence on mc/mbm_c/m_b. The application of a low-energy theorem allows the extraction of the three-loop effective Higgs-gluon coupling valid for extensions of the Standard Model with additional heavy quarks from the decoupling constant of αs\alpha_s.Comment: 30 page

    High precision determination of the gluon fusion Higgs boson cross-section at the LHC

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    We present the most precise value for the Higgs boson cross-section in the gluon-fusion production mode at the LHC. Our result is based on a perturbative expansion through N3^3LO in QCD, in an effective theory where the top-quark is assumed to be infinitely heavy, while all other Standard Model quarks are massless. We combine this result with QCD corrections to the cross-section where all finite quark-mass effects are included exactly through NLO. In addition, electroweak corrections and the first corrections in the inverse mass of the top-quark are incorporated at three loops. We also investigate the effects of threshold resummation, both in the traditional QCD framework and following a SCET approach, which resums a class of π2\pi^2 contributions to all orders. We assess the uncertainty of the cross-section from missing higher-order corrections due to both perturbative QCD effects beyond N3^3LO and unknown mixed QCD-electroweak effects. In addition, we determine the sensitivity of the cross-section to the choice of parton distribution function (PDF) sets and to the parametric uncertainty in the strong coupling constant and quark masses. For a Higgs mass of mH=125 GeVm_H = 125~{\rm GeV} and an LHC center-of-mass energy of 13 TeV13~{\rm TeV}, our best prediction for the gluon fusion cross-section is \[ \sigma = 48.58\,{\rm pb} {}^{+2.22\, {\rm pb}\, (+4.56\%)}_{-3.27\, {\rm pb}\, (-6.72\%)} \mbox{ (theory)} \pm 1.56 \,{\rm pb}\, (3.20\%) \mbox{ (PDF+αs\alpha_s)} \

    Vector-like bottom quarks in composite Higgs models

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    Altered ion transporter expression in bronchial epithelium in mountaineers with high-altitude pulmonary edema

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    BACKGROUND: The prevalence of overweight and obesity defined as BMI>/=25kg/m(2) is increasing, also among head and neck cancer patients. It is unknown whether the presence of high BMI influences disease-related mortality, overall survival and recurrence in these patients. METHODS: We reviewed available literature using Pubmed and Web of Science. Human observational studies were included if they reported the impact of high BMI on mortality, recurrence or survival for head and neck cancer. RESULTS: Eleven full articles and two abstracts met the inclusion criteria: six prospective and seven retrospective cohort studies, which comprised 8.306 patients. Patients with higher BMI had increased overall survival and decreased disease-related mortality and recurrence rate compared with underweight and normal weight patients. Most studies were adjusted for potentially confounding variables, such as stage of disease and smoking habits. CONCLUSION: High BMI is associated with a better outcome in head and neck cancer
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