389 research outputs found

    Model Independent Analysis of the Forward-Backward Asymmetry for the B→K1ÎŒ+Ό−B\to K_{1}\mu^{+}\mu^{-} Decay

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    The sensitivity of the zero position of the forward backward asymmetry AFB\mathcal{A}_{FB} for the exclusive B→K1(1270)ÎŒ+Ό−B\rightarrow K_{1}(1270)\mu^{+}\mu^{-} decay is examined by using most general non-standard 4-fermion interactions. Our analysis shows that the zero position of the forward backward asymmetry is very sensitive to the sign and size of the Wilson coefficients corresponding to the new vector type interactions, which are the counter partners of the usual Standard Model operators but have opposite chirality. In addition to these, the other significant effect comes from the interference of Scalar-Pseudoscalar and Tensor type operators. These results will not only enhance our theoretical understanding about the axial vector mesons but will also serve as a good tool to look for physics beyond the SM.Comment: 14 pages, 8 figures, Published version that appears in EPJ

    B→K1(1270)(→ρK)ℓ+ℓ−B \to K_1(1270) (\to \rho K) \ell^+ \ell^- in LEET

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    Flavour Changing Neutral Current decays of the BB-meson are a very useful tool for studying possible physics scenarios beyond the Standard Model (SM), where of the many FCNC modes radiative, purely leptonic and semi-leptonic decays of the BB-meson are relatively clean tests. Within this context the BELLE collaboration has searched for the B→K1(1270)ÎłB \to K_1(1270) \gamma process and provided an upper bound on this decay. In this work we have used this upper bound in studying the angular coorelations for the related semi-leptonic decay mode B→K1(1270)(→ρK)ℓ+ℓ−B \to K_1(1270) (\to \rho K) \ell^+ \ell^-, where we have used the form factors that have already been estimated for the B→K1(1270)ÎłB \to K_1(1270) \gamma mode. Note that the additional form factors that are required were calculated using the Large Energy Effective Theory (LEET).Comment: 13 pages, 4 figure

    Substantial reductions in the number of diabetic ketoacidosis and severe hypoglycaemia episodes requiring emergency treatment lead to reduced costs after structured education in adults with Type 1 diabetes

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    Aims To determine the impact of structured education promoting flexible intensive insulin therapy on rates of diabetic ketoacidosis, and the costs associated with emergency treatment for severe hypoglycaemia and ketoacidosis in adults with Type 1 diabetes. Methods Using the Dose Adjustment For Normal Eating research database we compared the rates of ketoacidosis and severe hypoglycaemia during the 12 months preceding Dose Adjustment For Normal Eating training with the rates during the 12-month follow-up after this training. Emergency treatment costs were calculated for associated paramedic assistance, Accident and Emergency department attendance and hospital admissions. Results Complete baseline and 1-year data were available for 939/1651 participants (57%). The risk of ketoacidosis in the 12 months after Dose Adjustment For Normal Eating training, compared with that before training, was 0.39 (95% CI: 0.23 to 0.65, P < 0.001), reduced from 0.07 to 0.03 episodes/patient/year. For every 1 mmol/mol unit increase in HbA1c concentration, the risk of a ketoacidosis episode increased by 6% (95% CI: 5 to 7%; 88% for a 1% increase), and for each 5-year increase in diabetes duration, the relative risk reduced by 20% (95% CI: 19 to 22%). The number of emergency treatments decreased for ketoacidosis (P < 0.001), and also for severe hypoglycaemia, including paramedic assistance (P < 0.001), Accident and Emergency department attendance (P = 0.029) and hospital admission (P = 0.001). In the study cohort, the combined cost of emergency treatment for ketoacidosis and severe hypoglycaemia fell by 64%, from ÂŁ119,470 to ÂŁ42,948. Conclusions Structured training in flexible intensive insulin therapy is associated with a 61% reduction in the risk of ketoacidosis and with 64% lower emergency treatment costs for ketoacidosis and severe hypoglycaemia

    Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules

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    Within the Standard Model, we investigate the weak decays of Λb→Λ+γ\Lambda_b \to \Lambda + \gamma and Λb→Λ+l+l−\Lambda_b \to \Lambda + l^{+} l^{-} with the light-cone sum rules approach. The higher twist distribution amplitudes of Λ\Lambda baryon to the leading conformal spin are included in the sum rules for transition form factors. Our results indicate that the higher twist distribution amplitudes almost have no influences on the transition form factors retaining the heavy quark spin symmetry, while such corrections can result in significant impacts on the form factors breaking the heavy quark spin symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of Λ\Lambda baryon are also employed in the sum rules for a comparison, which can give rise to the form factors approximately 5 times larger than that in terms of conformal expansion. Utilizing the form factors calculated in LCSR, we then perform a careful study on the decay rate, polarization asymmetry and forward-backward asymmetry, with respect to the decays of Λb→Λγ\Lambda_b \to \Lambda \gamma, Λl+l−\Lambda l^{+}l^{-}.Comment: 38 pages, 15 figures, some typos are corrected and more references are adde

    Analysis of the lepton polarisation asymmetries of Bˉ→Kˉ2(1430) ℓ+ ℓ−{\bar B} \to {\bar K}_2(1430) \, \ell^+ \, \ell^- decay

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    In this work we will study the longitudinal polarisations of both leptons in the decay process Bˉ→Kˉ2(1430) ℓ+ ℓ−{\bar B} \to {\bar K}_2(1430)\, \ell^+ \, \ell^-. This process has all the features of the related and well investigated process Bˉ→Kˉ∗(890) ℓ+ ℓ−{\bar B} \to {\bar K}^*(890) \, \ell^+ \, \ell^-, with theoretically comparable branching ratios. The polarised differential decay rates as well as the single and double polarisation asymmetries are worked out, where the sensitivity of these to possible right-handed couplings for the related b→sb \to s radiative decay (and other generic BSM parameters) are also investigated.Comment: 13 pages, 10 figures file

    Measurement of the partial widths of the Z into up- and down-type quarks

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    Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18} MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.

    Search for R-Parity Violating Decays of Scalar Fermions at LEP

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    A search for pair-produced scalar fermions under the assumption that R-parity is not conserved has been performed using data collected with the OPAL detector at LEP. The data samples analysed correspond to an integrated luminosity of about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle is expected to be unstable. Searches of R-parity violating decays of charged sleptons, sneutrinos and squarks have been performed under the assumptions that the lightest supersymmetric particle decays promptly and that only one of the R-parity violating couplings is dominant for each of the decay modes considered. Such processes would yield final states consisting of leptons, jets, or both with or without missing energy. No significant single-like excess of events has been observed with respect to the Standard Model expectations. Limits on the production cross- section of scalar fermions in R-parity violating scenarios are obtained. Constraints on the supersymmetric particle masses are also presented in an R-parity violating framework analogous to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.

    Infrastructure for Detector Research and Development towards the International Linear Collider

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    The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

    Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

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    An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic epep scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil
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