6,385 research outputs found

    SU(3)FSU(3)_F Meson Mass Formula from Random Phase Approximation

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    We present a SU(3)FSU(3)_F meson mass formula from random phase approximation (RPA). Both the mesons of ground-state pseudoscalar octet and the ground-state vector octet are described quite well in this mass formula. We also estimate the current and constituent quark masses from the na\"{\i}ve quark model with the PCAC relation

    Bs(d)0Bˉs(d)0B^0_{s(d)} - \bar{B}^0_{s(d)} mixing and new physics effects in a top quark two-Higgs doublet model

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    We calculate the new physics contributions to the neutral Bd0B_d^0 and Bs0B_s^0 meson mass splitting ΔMd\Delta M_d and ΔMs\Delta M_s induced by the box diagrams involving the charged-Higgs bosons in the top quark two-Higgs doublet model (T2HDM). Using the precision data, we obtain the bounds on the parameter space of the T2HDM: (a) for fixed MH=400M_H=400 GeV and δ=[0,60]\delta=[0^\circ,60^\circ], the upper bound on tanβ\tan{\beta} is tanβ30\tan \beta \leq 30 after the inclusion of major theoretical uncertainties; (b) for the case of tanβ20\tan{\beta} \leq 20, a light charged Higgs boson with a mass around 300 GeV is allowed; and (c) the bounds on tanβ\tan{\beta} and MHM_H are strongly correlated: a smaller (larger) tanβ\tan{\beta} means a lighter (heavier) charged Higgs boson.Comment: 11 pages, 2 EPS figures, RevTex, new references adde

    The Three-body Force and the Tetraquark Interpretation of Light Scalar Mesons

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    We study the possible tetraquark interpretation of light scalar meson states a0(980)a_0(980), f0(980)f_0(980), κ\kappa, σ\sigma within the framework of the non-relativistic potential model. The wave functions of tetraquark states are obtained in a space spanned by multiple Gaussian functions. We find that the mass spectra of the light scalar mesons can be well accommodated in the tetraquark picture if we introduce a three-body quark interaction in the quark model. Using the obtained multiple Gaussian wave functions, the decay constants of tetraquarks are also calculated within the ``fall apart'' mechanism

    Non-functional immunoglobulin G transcripts in a case of hyper-immunoglobulin M syndrome similar to type 4

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    86% of immunoglobulin G (IgG) heavy-chain gene transcripts were found to be non-functional in the peripheral blood B cells of a patient initially diagnosed with common variable immunodeficiency, who later developed raised IgM, whereas no non-functionally rearranged transcripts were found in the cells of seven healthy control subjects. All the patient's IgM heavy-chain and κ light-chain transcripts were functional, suggesting that either non-functional rearrangements were being selectively class-switched to IgG, or that receptor editing was rendering genes non-functional after class-switching. The functional γ-chain sequences showed a normal rate of somatic hypermutation while non-functional sequences contained few somatic mutations, suggesting that most came from cells that had no functional gene and therefore were not receiving signals for hypermutation. However, apoptosis of peripheral blood lymphocytes was not impaired. No defects have been found in any of the genes currently known to be responsible for hyper-IgM syndrome but the phenotype fits best to type 4

    The dispersive contribution of ρ(1450,1700)\rho(1450,1700) decays and X(1576)

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    We study whether the broad enhancement X(1576) arises from the final state interaction (FSI) of ρ(1450,1700)ρ+ρK+K\rho(1450,1700)\to \rho^+\rho^-\to K^{+}K^{-} decays. We consider both the absorptive and dispersive contribution of the above amplitudes since the intermediate states are very close to ρ(1450,1700)\rho(1450,1700). The same mechanism leads to a similar enhancement around 1580 MeV in the π+π\pi^{+}\pi^- spectrum in the J/ψπ0π+πJ/\psi\to \pi^{0}\pi^{+}\pi^{-} channel, which can be used to test whether X(1576) can be ascribed to the FSI effect of ρ(1450,1700)ρ+ρ\rho(1450,1700)\to \rho^+\rho^-.Comment: 4 pages, 4 figure

    (D* to D + gamma) and (B* to B + gamma) as derived from QCD Sum Rules

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    The method of QCD sum rules in the presence of the external electromagnetic FμνF_{\mu\nu} field is used to analyze radiative decays of charmed or bottomed mesons such as DDγD^{\ast}\to D\gamma and BBγB^{\ast}\to B\gamma, with the susceptibilities obtained previously from the study of baryon magnetic moments. Our predictions on DD^{\ast} decays agree very well with the experimental data. There are differences among the various theoretical predictions on BB^{\ast} decays but the data are not yet available.Comment: 11 pages, Late

    Flavor changing neutral currents from lepton and B decays in the two Higgs doublet model

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    Constraints on the whole spectrum of lepton flavor violating vertices are shown in the context of the standard two Higgs doublet model. The vertex involving the eτe-\tau mixing is much more constrained than the others, and the decays proportional to such vertex are usually very supressed. On the other hand, bounds on the quark sector are obtained from leptonic decays of the Bd,s0B_{d,s}^{0} mesons and from ΔMBd0\Delta M_{B_{d}^{0}}. We emphasize that although the Bd0Bˉd0B_{d}^{0}-\bar{B}_{d}^{0} mixing restricts severely the % d-b mixing vertex, the upper bound for this vertex could still give a sizeable contribution to the decay Bd0μμˉB_{d}^{0}\to \mu \bar{\mu} respect to the standard model contribution, from which we see that such vertex could still play a role in the phenomenology.Comment: 9 pages, 2 figures, LaTeX2e. Minor typos corrected. References added and corrected. Introduction change

    Sex-specific effects of nutritional supplements in infants born early or small: protocol for an individual participant data meta-analysis (ESSENCE IPD-MA).

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    INTRODUCTION: Preterm and small for gestational age (SGA) infants are at increased risk of poor growth, disability and delayed development. While growing up they are also at increased risk of obesity, diabetes and later heart disease. The risk of such adverse outcomes may be altered by how preterm and SGA infants are fed after birth. Faltering postnatal growth is common due to failure to achieve recommended high energy and protein intakes, and thus preterm and SGA infants are often provided with supplemental nutrition soon after birth. Enhanced nutrition has been associated with improved early growth and better cognitive development. However, limited evidence suggests that faster growth may increase the risk for later adiposity, metabolic and cardiovascular disease, and that such risks may differ between girls and boys. METHODS AND ANALYSIS: We will search Ovid MEDLINE, Embase, Cochrane CENTRAL, Cochrane Database of Systematic Reviews, controlled-trials.com, ClinicalTrials.gov and anzctr.org.au for randomised trials that studied the effects of macronutrient supplements for preterm and SGA infants on (i) developmental and metabolic and (ii) growth outcomes after hospital discharge. The outcomes will be (i) cognitive impairment and metabolic risk (co-primary) and (ii) body mass index. Individual participant data (IPD) from all available trials will be included using an intention-to-treat approach. A one-stage procedure for IPD meta-analysis (MA) will be used, accounting for clustering of participants within studies. Exploratory subgroup analyses will further investigate sources of heterogeneity, including sex and size of infants, different timing, duration and type of supplements. ETHICS AND DISSEMINATION: This IPD-MA is approved by the University of Auckland Human Participants Ethics Committee (reference number: 019874). Individual studies have approval from relevant local ethics committees. Results will be disseminated in a peer-reviewed journal and presented at international conferences. PROSPERO REGISTRATION NUMBER: CRD42017072683
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