639 research outputs found
Addendum: New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon [Phys. Rev. D 95, 054018 (2017)]
In this addendum to Phys.\ Rev.\ D {\bf 95}, 054018 (2017) we recompute the
rates for the decays of the Higgs boson to a vector quarkonium plus a photon,
where the vector quarkonium is , , , or
. We correct an error in the Abel-Pad\'e summation formula that
was used to carry out the evolution of the quarkonium light-cone distribution
amplitude in Phys.\ Rev.\ D {\bf 95}, 054018 (2017). We also correct an error
in the scale of quarkonium wave function at the origin in Phys.\ Rev.\ D {\bf
95}, 054018 (2017) and introduce several additional refinements in the
calculation.Comment: 7 pages, [v2] Abel-Pade summation formula corrected, [v3] PRD versio
-boson decays to a vector quarkonium plus a photon
We compute the decay rates for the processes , where is
the boson, is the photon, and is one of the vector quarkonia
or , with , , or . Our computations include
corrections through relative orders and and resummations of
logarithms of , to all orders in , at NLL accuracy. (
is the velocity of the heavy quark or the heavy antiquark in the
quarkonium rest frame, and and are the masses of and ,
respectively.) Our calculations are the first to include both the
order- correction to the light-cone distributions amplitude and the
resummation of logarithms of and are the first calculations for
the and final states. The resummations of
logarithms of that are associated with the order- and
order- corrections are carried out by making use of the Abel-Pad\'e
method. We confirm the analytic result for the order- correction that was
presented in a previous publication, and we correct the relative sign of the
direct and indirect amplitudes and some choices of scales in that publication.
Our branching fractions for and
differ by and , respectively, from the branching
fractions that are given in the most recent publication on this topic (in units
of the uncertainties that are given in that publication). However, we argue
that the uncertainties in the rates are underestimated in that publication.Comment: 26 pages, [v2] references added / [v3] Equation (27) modified, 3
sentences added after Eq. (27), Reference [17] added / [v4] PRD versio
New approach to the resummation of logarithms in Higgs-boson decays to a vector quarkonium plus a photon
We present a calculation of the rates for Higgs-boson decays to a vector
heavy-quarkonium state plus a photon, where the heavy quarkonium states are the
J/psi and the Upsilon(nS) states, with n=1, 2, or 3. The calculation is carried
out in the light-cone formalism, combined with nonrelativistic QCD
factorization, and is accurate at leading order in m_Q^2/m_H^2, where m_Q is
the heavy-quark mass and m_H is the Higgs-boson mass. The calculation contains
corrections through next-to-leading order in the strong-coupling constant
alpha_s and the square of the heavy-quark velocity v, and includes a
resummation of logarithms of m_H^2/m_Q^2 at next-to-leading logarithmic
accuracy. We have developed a new method, which makes use of Abel summation,
accelerated through the use of Pade approximants, to deal with divergences in
the resummed expressions for the quarkonium light-cone distribution amplitudes.
This approach allows us to make definitive calculations of the resummation
effects. Contributions from the order-alpha_s and order-v^2 corrections to the
light-cone distribution amplitudes that we obtain with this new method differ
substantially from the corresponding contributions that one obtains from a
model light-cone distribution amplitude [M. Koenig and M. Neubert, J. High
Energy Phys. 08 (2015) 012]. Our results for the real parts of the
direct-process amplitudes are considerably smaller than those from one earlier
calculation [G. T. Bodwin, H. S. Chung, J.-H. Ee, J. Lee, and F. Petriello,
Phys. Rev. D 90, 113010 (2014)], reducing the sensitivity to the
Higgs-boson--heavy-quark couplings, and are somewhat smaller than those from
another earlier calculation [M. Koenig and M. Neubert, J. High Energy Phys. 08
(2015) 012]. However, our results for the standard-model Higgs-boson branching
fractions are in good agreement with those in M. Koenig and M. Neubert, J. High
Energy Phys. 08 (2015) 012.Comment: 40 pages, improved discussion of the convergence of the
nonrelativistic expansion, minor corrections and changes in nomenclature,
version published in Phys. Rev.
Vav1 inhibits RANKL-induced osteoclast differentiation and bone resorption
Vav1 is a Rho/Rac guanine nucleotide exchange factor primarily expressed in hematopoietic cells. In this study, we investigated the potential role of Vav1 in osteoclast (OC) differentiation by comparing the ability of bone marrow mononuclear cells (BMMCs) obtained from Vav1-deficient (Vav1−/−) and wild-type (WT) mice to differentiate into mature OCs upon stimulation with macrophage colony stimulating factor and receptor activator of nuclear kappa B ligand in vitro. Our results suggested that Vav1 deficiency promoted the differentiation of BMMCs into OCs, as indicated by the increased expression of tartrate-resistant acid phosphatase, cathepsin K, and calcitonin receptor. Therefore, Vav1 may play a negative role in OC differentiation. This hypothesis was supported by the observation of more OCs in the femurs of Vav1−/− mice than in WT mice. Furthermore, the bone status of Vav1−/− mice was analyzed in situ and the femurs of Vav1−/− mice appeared abnormal, with poor bone density and fewer number of trabeculae. In addition, Vav1-deficient OCs showed stronger adhesion to vitronectin, an αvβ3 integrin ligand important in bone resorption. Thus, Vav1 may inhibit OC differentiation and protect against bone resorption
Angiopoietin-1 is an apoptosis survival factor for endothelial cells
AbstractWe examined the effect of angiopoietin-1 (Ang1) on apoptosis in human umbilical vein endothelial cells (HUVECs). Ang1 (5–1000 ng/ml) dose-dependently inhibited apoptosis under a serum-deprived state. A significant apoptotic inhibition occurred with as low as 50 ng/ml. Two hundred ng/ml of Ang1 inhibited to approximately 50% of the control apoptotic rates for 96 h. Furthermore, an augmented antiapoptotic effect of Ang1 by the addition of 20 ng/ml vascular endothelial growth factor was observed. This Ang1-induced strong antiapoptotic effect in endothelial cells is a novel and intriguing finding and could be an additional description of Ang1-induced direct biological function
Role of Hydrogen in Active Layer of Oxide-Semiconductor-Based Thin Film Transistors
Hydrogen in oxide systems plays a very important role in determining the major physical characteristics of such systems. In this study, we investigated the effect of hydrogen in oxide host systems for various oxygen environments that acted as amorphous oxide semiconductors. The oxygen environment in the sample was controlled by the oxygen gas partial pressure in the radio-frequency-sputtering process. It was confirmed that the hydrogen introduced by the passivation layer not only acted as a “killer” of oxygen deficiencies but also as the “creator” of the defects depending on the density of oxide states. Even if hydrogen is not injected, its role can change owing to unintentionally injected hydrogen, which leads to conflicting results. We discuss herein the correlation with hydrogen in the oxide semiconductor with excess or lack of oxygen through device simulation and elemental analysis. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.1
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