5,087 research outputs found

    Non-Perturbative Renormalisation using Domain Wall Fermions

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    The viability of the Non-Perturbative Renormalisation (NPR) method of the Rome/Southampton group is studied, for the first time, in the context of domain wall fermions. The procedure is used to extract the renormalisation coefficients of the various quark bilinears, as well as the four-fermion operators relevant to the ΔS=2\Delta S=2 effective Hamiltonian. The renormalisation of the ΔS=1\Delta S=1 Hamiltonian is also discussed.Comment: LATTICE99(Improvement and Renormalization),3 pages, LaTeX2e; minor typos correcte

    Non-perturbative Renormalisation with Domain Wall Fermions

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    We present results from a study of the renormalisation of both quark bilinear and four-quark operators for the domain wall fermion action, using the non-perturbative renormalisation technique of the Rome-Southampton group. These results are from a quenched simulation, on a 16^3 x 32 lattice, with beta=6.0 and L_s=16.Comment: 4 pages, 6 figures, Lattice 2000 (Improvement and Renormalisation), RBC collaboration, Typos correcte

    Invisible Z decay width bounds on active-sterile neutrino mixing in the (3+1) and (3+2) models

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    In this work we consider the standard model extended with singlet sterile neutrinos with mass in the eV range and mixed with the active neutrinos. The active-sterile neutrino mixing renders new contributions to the invisible Z decay width which, in the case of light sterile neutrinos, depends on the active-sterile mixing matrix elements only. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models.Comment: 10 pages, 5 figure

    Non-Perturbative Renormalisation of the Lattice Δs=2\Delta s=2 Four-Fermion Operator

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    We compute the renormalised four-fermion operator OΔS=2O^{\Delta S=2} using a non-perturbative method recently introduced for determining the renormalisation constants of generic lattice composite operators. Because of the presence of the Wilson term, OΔS=2O^{\Delta S=2} mixes with operators of different chiralities. A projection method to determine the mixing coefficients is implemented. The numerical results for the renormalisation constants have been obtained from a simulation performed using the SW-Clover quark action, on a 163×3216^3 \times 32 lattice, at β=6.0\beta=6.0. We show that the use of the constants determined non-perturbatively improves the chiral behaviour of the lattice kaon matrix element \_{\latt}.Comment: LaTeX, 16 pages, 2 postscript figure

    N=1 Super Yang-Mills on the Lattice in the Strong Coupling Limit

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    We study the N=1 supersymmetric SU(N) Yang-Mills theory on the lattice at strong coupling. We analyse and discuss the recent results obtained at strong coupling and large N for the mesonic and fermionic propagators and spectrum.Comment: Latex 3 pages. Contribution to the Lattice99 Proceeding

    Clone flow analysis for a theory inspired Neutrino Experiment planning

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    The presence of several clone solutions in the simultaneous measurement of (θ13,δ\theta_{13},\delta) has been widely discussed in literature. In this letter we write the analytical formulae of the clones location in the (θ13,δ\theta_{13},\delta) plane as a function of the physical input pair (θˉ13,δˉ\bar\theta_{13},\bar\delta). We show how the clones move with changing θˉ13\bar\theta_{13}. The "clone flow" can be significantly different if computed (naively) from the oscillation probabilities or (exactly) from the probabilities integrated over the neutrino flux and cross-section. Using our complete computation we compare the clone flow of a set of possible future neutrino experiments: the CERN SuperBeam, BetaBeam and Neutrino Factory proposals. We show that the combination of these specific BetaBeam and SuperBeam does not help in solving the degeneracies. On the contrary, the combination of one of them with the Neutrino Factory Golden and Silver channel can be used, from a theoretical point of view, to solve completely the eightfold degeneracy.Comment: 23 pages, using epsfi

    Circulating SIRT1 inversely correlates with epicardial fat thickness in patients with obesity

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    Background and aim: Obesity is increasing worldwide and is related to undesirable cardiovascular outcomes. Epicardial fat (EF), the heart visceral fat depot, increases with obesity and correlates with cardiovascular risk. SIRT1, an enzyme regulating metabolic circuits linked with obesity, has a cardioprotective effect and is a predictor of cardiovascular events. We aimed to assess the relationship of EF thickness (EFT) with circulating SIRT1 in patients with obesity. Methods and results: Sixty-two patients affected by obesity and 23 lean controls were studied. Plasma SIRT1 concentration was determined by enzyme-linked immunosorbent assay (ELISA). EFT was measured by echocardiography. Body mass index (BMI), waist circumference, heart rate (HR), blood pressure, and laboratory findings (fasting glucose, insulin, HbA1c, cholesterol, and triglycerides) were assessed. SIRT1 was significantly lower (P = 0.002) and EFT was higher (P < 0.0001) in patients with obesity compared with lean controls. SIRT1 showed a negative correlation with EFT and HR in the obesity group (rho = -0.350, P = 0.005; rho = -0.303, P = 0.008, respectively). After adjustment for obesity-correlated variables, multiple linear regression analysis showed that EFT remained the best correlate of SIRT1 (beta = -0.352, P = 0.016). Conclusions: Circulating SIRT1 correlates with the visceral fat content of the heart. Serum SIRT1 levels might provide additional information for risk assessment of coronary artery disease in patients with obesity. (C) 2016 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved

    Non-perturbative scale evolution of four-fermion operators

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    We apply the Schroedinger Functional (SF) formalism to determine the renormalisation group running of four-fermion operators which appear in the effective weak Hamiltonian of the Standard Model. Our calculations are done using Wilson fermions and the parity-odd components of the operators. Preliminary results are presented for the operator OVA=(sˉγμd)(sˉγμγ5d)O_{VA}=(\bar s \gamma_\mu d)(\bar s \gamma_\mu \gamma_5 d).Comment: Lattice2002(improve

    New interactions: past and future experiments

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    In this talk I will review the present status and future perspectives of some popular extensions of the conventional three-neutrino oscillation scenario, from a purely phenomenological point of view. For concreteness I will focus only on three specific scenarios: non-standard neutrino interactions with matters, models with extra sterile neutrinos, and neutrino decay and decoherence.Comment: LaTeX file using jpconf class, 8 pages, 2 tables. Proceedings of the "XXIII International Conference on Neutrino Physics and Astrophysics" (Neutrino 08), Christchurch, New Zealand, May 25-31, 200

    Locating the alien chromatin segment in common wheat-Aegilops longissima mildew resistant transfers

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    By use of the Chinese Spring ph 1b mutant, recombination was induced between the 3S1 short arm telosome of Ae. longissima and its group-3 wheat homoeologues. Transfer was thus obtained of chromosomal segments bearing the alien Pm 13 mildew resistance gene into several common wheat lines. To identify the wheat chromosome involved in each transfer, these were subjected to monosomic and C-banding analyses. Probably due to preferential 3B-3S1 pairing, irrespective of the group-3 wheat chromosome present as monosome in the critical steps of the transfer work, in 2/3 of the cases 3B turned out to be the recipient chromosome, whereas 3D was the one involved in the remaining ones. Assessment of the residual pairing ability of the recombinant chromosomes in F1's between four 3B and three 3D transfer lines and their corresponding wheat ditelosomic as well as 3S1 substitution lines, indicated about coincident values (about 40 % pairing with DT3BS) in three of the 3B recombinants, a significantly different pattern in the fourth one (10 %) and a more continuous variation among the 3D ones. An overall prevailing terminal location of the wheat-alien chromatin exchange points is tentatively hypothesized
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