3,131 research outputs found

    A Light Sterile Neutrino in the TopFlavor Model

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    A scenario based on the TopFlavor model is presented to explain the origin of a light sterile neutrino as indicated by all combined neutrino oscillation experiments. The model is phenomenologically well motivated and compatible with all available low-energy data. The derived nuetrino mass matrix can qualitatively explain the observed hierarchy in the neutrino mass splittings as indicated by the neutrino oscillation data. Numerical results are obtained for special cases.Comment: Plain Latex file, 12 page

    B \to K(K^*) missing energy in Unparticle physics

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    In the present work we study the effects of an unparticle \unpart as the possible source of missing energy in the decay BK(K)+missingenergyB \to K (K^*) + {\rm missing energy}. We find that the dependence of the differential branching ratio on the KK(KK^*)-meson's energy in the presence of the vector unparticle operators is very distinctive from that of the SM. Moreover, in using the existing upper bound on BK(K)+missingenergyB \to K (K^*) + {\rm missing energy} decays, we have been able to put more stringent constraints on the parameters of unparticle stuff.Comment: 13 pages, 5 figure

    Revising Neutrino Oscillation Parameter Space With Direct Flavor-Changing Interactions

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    We formulate direct, neutrino flavor-changing interactions in a framework that fits smoothly with the parameterization of two-and three-state mixing of massive neutrino states. We show that even small direct interaction strengths could have important consequences for the interpretation of currently running and proposed oscillation experiments. The oscillation amplitude and the borders of the allowed regions in two-and three-flavor mixing parameter space can be sensitieve to the presence of direct interactions when the transition probability is small. We use extensively the high sensitivity of the NOMAD experiment to illustrate potentially large effects from small, direct flavor violation. In the purely leptonic sector, we find that the clean muon neutrino and electron neutrino beams from a muon collider could provide the sharpest tests of direct flavor violation.Comment: 16 pages, 10 figure

    Constraints On Radiative Neutrino Mass Models From Oscillation Data

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    The three neutrino Zee model and its extension including three active and one sterile species are studied in the light of new neutrino oscillation data. We obtain analytical relations for the mixing angle in solar oscillations in terms of neutrino mass squared differences. For the four neutrino case, we obtain the result sin22θ1[(ΔmAtm2)2/(4ΔmLSND2Δm2)]2\mathsf{sin^2 2 \theta_\odot \approx 1 - [ (\Delta m^2_{Atm})^2/(4 \Delta m^2_{LSND} \Delta m^2_\odot) ]^2}, which can accommodate both the large and small mixing scenarios. We show that within this framework, while both the SMA-MSW and the LMA-MSW solutions can easily be accommodated, it would be difficult to reconcile the LOW-QVO solutions. We also comment on the active-sterile admixture within phenomenologically viable textures.Comment: The paper has been substantially rewritten, especially in Section IV, though the basic results are unchanged. Some new references and an appendix have been adde

    Unparticle Physics in Single Top Signals

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    We study the single production of top quarks in e+e,epe^+e^-, ep and pppp collisions in the context of unparticle physics through the Flavor Violating (FV) unparticle vertices and compute the total cross sections for single top production as functions of scale dimension d_{\U}. We find that among all, LHC is the most promising facility to probe the unparticle physics via single top quark production processes.Comment: 14 pages, 10 figure

    Search for Bs0γγB_{s}^{0}\rightarrow\gamma\gamma and a measurement of the branching fraction for Bs0ϕγB_{s}^{0}\rightarrow\phi\gamma

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    We search for the decay Bs0γγB_{s}^{0}\rightarrow\gamma\gamma and measure the branching fraction for Bs0ϕγB_{s}^{0}\rightarrow\phi\gamma using 121.4~fb1\textrm{fb}^{-1} of data collected at the Υ(5S)\Upsilon(\mathrm{5}S) resonance with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider. The Bs0ϕγB_{s}^{0}\rightarrow\phi\gamma branching fraction is measured to be (3.6±0.5(stat.)±0.3(syst.)±0.6(fs))×105(3.6 \pm 0.5 (\mathrm{stat.}) \pm 0.3 (\mathrm{syst.}) \pm 0.6 (f_{s})) \times 10^{-5}, where fsf_{s} is the fraction of Bs()Bˉs()B_{s}^{(*)}\bar{B}_{s}^{(*)} in bbˉb\bar{b} events. Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb. We observe no statistically significant signal for the decay Bs0γγB_{s}^{0}\rightarrow\gamma\gamma and set a 90%90\% confidence-level upper limit on its branching fraction at 3.1×106 3.1 \times 10^{-6}. This constitutes a significant improvement over the previous result.Comment: 6 pages, 3 figure

    Field response of chickpea (Cicer arietinum L.) to high temperature

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    High temperature is an important factor affecting chickpea growth, development and grain yield. Understanding the plant response to high temperature is a key strategy in breeding for heat tolerance in chickpea (Cicer arietinum L.). This study assessed genetic variability for heat tolerance in chickpea and identified sources of heat tolerance that could be used for crop improvement. One hundred and sixty-seven genotypes were grown in two environments (heat stressed/late sown and non-stressed/optimal sowing time) in 2 years (2009–2010 and 2010–2011) at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India. Large genetic variation was observed for phenology, growth, yield components and grain yield. While phenology (assessed as days to first flower, days to 50% flowering and days to first pod) was negatively correlated with grain yield at high temperature; plant biomass, pod number, filled pod number and seed number per plant were positively correlated. Genotypes were classified into short and long duration groups based on their maturity. Days to first flowering (DFF) of long duration genotypes were negatively associated with grain yield under stressed conditions in both years compared with medium to short duration genotypes. However, genotypes varied in their heat sensitivity and temperatures ≥35 °C produced yield losses up to 39%. A heat tolerance index (HTI) classified the genotypes into five groups: (i) stable heat tolerant (>0.5), (ii) moderately heat tolerant (0.1–0.49), (iii) stable heat sensitive (−ve values), (iv) heat tolerant to moderately sensitive (−0.10 to 1) and (v) heat sensitive to moderately tolerant (−0.5 to 0.4). Pod characteristics, including days to first pod and pod number per plant, were correlated with grain yield whereas canopy temperature depression (CTD) was generally not correlated. Heat tolerant genotypes in a range of maturities were identified that could be used to improve the heat tolerance of chickpea

    High temperature tolerance in chickpea and its implications for plant improvement

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    Chickpea (Cicer arietinum L.) is an important food legume and heat stress affects chickpea ontogeny over a range of environments. Generally, chickpea adapts to high temperatures through an escape mechanism. However, heat stress during reproductive development can cause significant yield loss. The most important effects on the reproductive phase that affect pod set, seed set and yield are: (1) flowering time, (2) asynchrony of male and female floral organ development, and (3) impairment of male and female floral organs. While this review emphasises the importance of high temperatures >30°C, the temperature range of 32–35°C during flowering also produces distinct effects on grain yield. Recent field screening at ICRISAT have identified several heat-tolerant germplasm, which can be used in breeding programs for improving heat tolerance in chickpea. Research on the impact of heat stress in chickpea is not extensive. This review describes the status of chickpea production, the effects of high temperature on chickpea, and the opportunities for genetic improvement of chickpea tolerance to high temperatures

    Search for D0D^{0} decays to invisible final states at Belle

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    We report the result from the first search for D0D^0 decays to invisible final states. The analysis is performed on a data sample of 924 fb1\rm{fb}^{-1} collected at and near the Υ(4S)\Upsilon(4S) and Υ(5S)\Upsilon(5S) resonances with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider. The absolute branching fraction is determined using an inclusive D0D^0 sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of 9.4×1059.4\times 10^{-5} is set on the branching fraction of D0D^0 to invisible final states at 90\% confidence level.Comment: 17 pages, 4 figures, submitted to PRD(RC
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