651 research outputs found

    Large pTp_T Hadroproduction of ZZ as a Probe of Gluon Distribution inside Proton

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    The transverse momentum distribution of single vector boson production at hadron colliders provides useful ways of testing the Standard Model and searching new physics beyond the Standard Model. We study large pTp_{_T} hadroproduction of ZZ-boson as a probe of gluon distributions inside proton. We investigate how to get initial gluon-involving contributions, or how to subtract quark-quark (or -antiquark) contributions from total cross section. We also investigated the simultaneous measurement of the rapidity and the transverse momentum of the produced ZZ boson, to obtain momentum fractions of initial partons. And we extracted relevant uncertainties involving in experimental and theoretical analyses. This large pTp_{_T} hadroproduction of ZZ can be used as constraints on analyses of global parton (gluon and quarks) distribution functions inside proton.Comment: (a) 13 pages(LaTeX) + 1 figure ps file(3 pages):compressed, uuencoded (b) accepted by Phys.Lett.B. (c) some figures are combined and one is omitted. (d) conclusion part is included into abstrac

    Interactions between Grape Maturity Indices and Quality for Pinotage and Cabernet Sauvignon Wines from Four Localities

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    Three grape maturity indices viz. degrees Balling (OB), OB total titratable acid (TT A) ratio and the OB.pH product of musts were compared regarding their ability to predict optimum quality for Cabernet Sauvignon and Pinotage wines. Comprehensive analytical data from 128 musts and corresponding wines for the 1979 and 1980 vintages from the Stellenbosch, Durbanville, Lutzville and Robertson areas were subjected to principal component analysis using variables and variable ratios selected by correlation to quality weighting. The results indicated that 0B alone could not perform the function of a grape maturity index for predicting optimum quality. In the case of the OB/TT A index, the range wherein maximum wine quality occurred was too wide tobe of practical value in this instance. The 0B.pH index gave a narrower optimum range, and in contrast to the two other indices gave similar results for both cultivars

    Extended double seesaw model for neutrino mass spectrum and low scale leptogenesis

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    We consider a variant of seesaw mechanism by introducing extra singlet neutrinos, with which we show how the low scale leptogenesis is realized without imposing the tiny mass splitting between two heavy Majorana neutrinos required in the resonant leptogenesis. Thus, we can avoid the so-called gravitino problem when our scenario is supersymmetrized. We show that an introduction of the new singlet fermion leads to a new contribution which can enhance the lepton asymmetry for certain range of parameter space. We also examine how both the light neutrino mass spectrum and relatively light sterile neutrinos of order a few 100 MeV can be achieved without being in conflict with the constraints on the mixing between the active and sterile neutrinos.Comment: RevTex 12 pages, 1 figure, title changed, typos corrected, numerical results improved, to appear in Phys. Lett.

    SUSY-QCD Effect on Top-Charm Associated Production at Linear Collider

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    We evaluate the contribution of SUSY-QCD to top-charm associated production at next generation linear colliders. Our results show that the production cross section of the process e+etcˉortˉce^+e^-\to t\bar c{or}\bar t c could be as large as 0.1 fb, which is larger than the prediction of the SM by a factor of 10810^8.Comment: version to appear in PR

    Virtual SUSY Threshold Effects and CDF large ETE_{T} Anomaly

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    Recent CDF data of the inclusive jet cross section shows threshold-like structured deviation, around transverse momentum ET(j)200350E_T(j)\approx 200 \sim 350 GeV. If this data is real, not just some statistical fluctuation, is it possible to interpret the anomaly in terms of virtual SUSY effects? The purpose of this note is to address this question. However, we find that virtual SUSY loop interference effects [near the threshold] are too small to explain the CDF data. Our main conclusion seems to be on the right track if we assume that the recent global analysis of improved parton distributions by Lai et al. is correct. PACS number(s): 14.65.Ha, 12.38.Bx, 12.60.Jv, 13.85.-tComment: 10 pages, RevTex, 1 Tex file and 5-page postscript together, To appear in Phys.Lett.

    Virtual Effects of Split SUSY in Higgs Productions at Linear Colliders

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    In split supersymmetry the gauginos and higgsinos are the only supersymmetric particles possibly accessible at foreseeable colliders like the CERN Large Hadron Collider (LHC) and the International Linear Collider (ILC). In order to account for the cosmic dark matter measured by WMAP, these gauginos and higgsinos are stringently constrained and could be explored at the colliders through their direct productions and/or virtual effects in some processes. The clean environment and high luminosity of the ILC render the virtual effects of percent level meaningful in unraveling the new physics effects. In this work we assume split supersymmetry and calculate the virtual effects of the WMAP-allowed gauginos and higgsinos in Higgs productions e+e- -> Z h and e+e- -> \nu_e \bar_\nu_e h through WW fusion at the ILC. We find that the production cross section of e+e- -> Zh can be altered by a few percent in some part of the WMAP-allowed parameter space, while the correction to the WW-fusion process e+e- -> \nu_e \bar_\nu_e h is below 1%. Such virtual effects are correlated with the cross sections of chargino pair productions and can offer complementary information in probing split supersymmetry at the colliders.Comment: more discussions added (7 pages, 10 figs

    Dietary quality and patterns and non-communicable disease risk of an Indian community in KwaZulu-Natal, South Africa

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    BACKGROUND : Limited data exist on the South African Indian diet despite their high prevalence of non-communicable diseases. This study attempted to determine the dietary quality and patterns of an Indian population in KwaZulu-Natal with reference to the high prevalence of non-communicable disease METHODS : Two-hundred-and-fifty apparently healthy Indians, aged 35–55 years participated in a cross-sectional study where diet was assessed using a validated quantitative food frequency questionnaire. Mean intakes were compared to the World Health Organization goals. Dietary quality was determined by index construction and dietary patterns by factor analysis. RESULTS : The mean daily percentage of energy (%E) from n-3 fatty acids (0.24 %E), dietary fibre (18.4 g/day) and fruit and vegetable intakes (229.4 g/day) were below the World Health Organization goals. Total fat (36.1 %E), polyunsaturated fatty acids (11.8 %E), n-6 fatty acids (11 %E) and free sugars (12.5 %E) exceeded the goals. The means for the deficient index reflected a moderate diet quality whereas, the excess index reflected good diet quality. The Pearson partial correlation coefficients between the deficient index and risk markers were weak whilst, the excess index was inversely correlated with waist circumference for the whole sample. Two factors were identified, based on the percentage of fat that contributed to each food group: factor 1 (meat and fish versus legume and cereal pattern), which accounted for added fat through food preparation; and Factor 2 (nuts and seeds versus sugars and visible fat pattern), which accounted for obvious fat. The medians for waist circumference, blood glucose, cholesterol and triglyceride levels showed significant decreasing trends for factor 1 (p < 0.05). The medians for blood glucose and cholesterol showed significant decreasing trends for factor 2 (p < 0.01). CONCLUSION : A shortfall of fruit and vegetable, fibre and n-3 fatty acid intake in the diet is highlighted. When assessing the diet quality and patterns, guidance on the prudent use of added fats may lead to a healthier lifestyle reducing the prevalence of non-communicable diseases.Grants from the South African Medical Research Council, National Research Foundation; Thuthuka and North-West University.am201

    Flavor Democracy in Standard Models at High Energies

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    It is possible that the standard model (SM) is replaced around some transition energy \E_{tr} by a new, possibly Higgsless, ``flavor gauge theory'' such that the Yukawa (running) parameters of SM at E \sim \E_{tr} show up an (approximate) flavor democracy (FD). We investigate the latter possibility by studying the renormalization group equations for the Yukawa couplings of SM with one and two Higgs doublets, by evolving them from given physical values at low energies (E1GeVE \simeq 1 GeV) to \E_{tr} ( \sim \E_{pole}) and comparing the resulting fermion masses and CKM matrix elements at E \simeq \E_{tr} for various mtphym_t^{phy} and ratios vu/vdv_u/v_d of vacuum expectation values. We find that the minimal SM and the closely related SM with two Higgs doublets (type I) show increasing deviation from FD when energy is increased, but that SM with two Higgs doublets (type II) clearly tends to FD with increasing energy - in both the quark and the leptonic sector (q-q and l-l FD). Furthermore, we find within the type II model that, for \E_{pole} \ll \E_{Planck}, mtphym_t^{phy} can be less than 200GeV200 GeV in most cases of chosen vu/vdv_u/v_d. Under the assumption that also the corresponding Yukawa couplings in the quark and the leptonic sector at E \simeq \E_{tr} are equal (l-q FD), we derive estimates of bounds on masses of top quark and tau-neutrino, which are compatible with experimental bounds.Comment: 23 pages (7 Figs. available on request), standard LATEX, preprint DO-TH 93-08, SNUTP 93-12, YUMS 93-0

    Supersymmetric CP Violation in BXsl+lB \to X_s l^+ l^- in Minimal Supergravity Model

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    Direct CP asymmetries and the CP violating normal polarization of lepton in inclusive decay B \to X_s l^+ l^- are investigated in minimal supergravity model with CP violating phases. The contributions coming from exchanging neutral Higgs bosons are included. It is shown that the direct CP violation in branching ratio, A_{CP}^1, is of {\cal{O}}(10^{-3}) for l=e, \mu, \tau. The CP violating normal polarization for l=\mu can reach 0.5 percent when tan\beta is large (say, 36). For l=\tau and in the case of large \tan\beta, the direct CP violation in backward-forward asymmetry, A_{CP}^2, can reach one percent, the normal polarization of \tau can be as large as a few percent, and both are sensitive to the two CP violating phases, \phi_\mu and \phi_{A_0}, and consequently it could be possible to observe them (in particular, the normal polarization of \tau) in the future B factories.Comment: 14 pages, latex, 5 figure

    Higgs-mediated leptonic decays of B_s and B_d mesons as probes of supersymmetry

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    If tan(beta) is large, down-type quark mass matrices and Yukawa couplings cannot be simultaneously diagonalized, and flavour violating couplings of the neutral Higgs bosons are induced at the 1-loop level. These couplings lead to Higgs-mediated contributions to the decays B_s -> mu+ mu- and B_d -> tau+ tau-, at a level that might be of interest for the current Tevatron run, or possibly, at B-factories. We evaluate the branching ratios for these decays within the framework of minimal gravity-, gauge- and anomaly-mediated SUSY breaking models, and also in SU(5) supergravity models with non-universal gaugino mass parameters at the GUT scale. We find that the contribution from gluino loops, which seems to have been left out in recent phenomenological analyses, is significant. We explore how the branching fraction varies in these models, emphasizing parameter regions consistent with other observations.Comment: Revised to accommodate minor changes in original text and update reference
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