11,740 research outputs found

    νμ\nu_\mu disappearance at the SPL, T2K-I and the Neutrino Factory

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    We study the νμ\nu_\mu disappearance channel at T2K-phase I and the SPL and analyse the achievable reduction of present uncertainties in θ23\theta_{23} and Δm232\Delta m^2_{23}. We analyse the impact of discrete ambiguities in sign(Δm223\Delta m^2{23}) and sign(2tanθ232 \tan \theta_{23}). We show how the disappearance channel at the Neutrino Factory is complementary to the ``golden'' and ``silver'' appearance channels and can be used to reduce the eightfold-ambiguity problem in (θ13δ\theta_{13}-\delta).Comment: 2 pages, 3 epsfig; NUFACT'05, 21-26 June 2005, Frascat

    Using nu_e -> nu_tau: golden and silver channels at the Neutrino Factory

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    I briefly review the source of the so-called intrinsic ambiguity and show how the combination of ``golden'' and ``silver'' channel at the Neutrino Factory can solve the problem, in the absence of other sources of degeneracies. I then relaxed the hypothesis θ23=45\theta_{23} = 45^\circ and show how the different dependence of the two channels on θ23\theta_{23} can help in solving the intrinsic and θ23\theta_{23}-octant ambiguity at the same time.Comment: 6 pages, 7 figs. using epsfig; proceedings of the NOON 2003 Workshop, February 10-14, 2003, Kanazawa, Japa

    Non-perturbative Renormalization of the Complete Basis of Four-fermion Operators and B-parameters

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    We present results on the B-parameters BKB_K, B73/2B^{3/2}_7 and B83/2B^{3/2}_8, at β=6.0\beta=6.0, with the tree-level Clover action. The renormalization of the complete basis of dimension-six four-fermion operators has been performed non-perturbatively. Our results for BKB_K and B73/2B^{3/2}_7 are in reasonable agreement with those obtained with the (unimproved) Wilson action. This is not the case for B83/2B^{3/2}_8. We also discuss some subtleties arising from a recently proposed modified definition of the B-parameters.Comment: Talk presented at Lattice '97, Edinburgh (UK), July 1997. LaTeX 3 pages, uses espcrc

    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

    Micro-orbits in a many-branes model and deviations from 1/r21/r^2 Newton's law

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    We consider a 5-dimensional model with geometry M=M4×S1{\cal M} = {\cal M}_4 \times {\cal S}_1, with compactification radius RR. The Standard Model particles are localized onto a brane located at y=0, with identical branes localized at different points in the extra dimension. Objects located on our brane can orbit around objects located on a brane at a distance d=y/Rd=y/R, with an orbit and a period significantly different from the standard Newtonian ones. We study the kinematical properties of the orbits, finding that it is possible to distinguish one motion from the other in a large region of the initial conditions parameter space. This is a warm-up to study if a SM-like mass distribution on one (or more) distant brane(s) may represent a possible dark matter candidate. After using the same technique to the study of orbits of objects lying on the same brane (d=0d=0), we apply this method to detect generic deviations from the inverse-square Newton's law. We propose a possible experimental setup to look for departures from Newtonian motion in the micro-world, finding that an order of magnitude improvement on present bounds can be attained at the 95% CL under reasonable assumptions.Comment: Two-column format (20 pages), 10 figures; minor corrections and some added reference

    νμ\nu_\mu disappearance at the SPL, T2K-I, NOν\nuA and the Neutrino Factory

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    We study the measurement of the atmospheric neutrino oscillation parameters, θ23\theta_{23} and Δm232\Delta m^2_{23}, at the νμ\nu_\mu disappearance channel at three conventional beam facilities, the SPL, T2K-phase I and NOν\nuA. These two parameters have been shown to be of crucial importance in the measurement of two of the unknowns of the PMNS mixing matrix, θ13\theta_{13} and the leptonic CP-violating phase δ\delta. In our analyis, the effect of the two discrete ambiguities, sign(Δm232){\rm sign}(\Delta m^2_{23}) and sign(tan2θ23){\rm sign}(\tan 2 \theta_{23}), is explicitly taken into account. We analyse also the νμ\nu_\mu disappearance channel at the Neutrino Factory, and combine it with the ``golden'' νeνμ\nu_e \to \nu_\mu and ``silver'' νeντ\nu_e \to \nu_\tau appearance channels to study its impact on the measurement of θ13\theta_{13} and δ\delta. Eventually, we present the sensitivity of the four facilities to different observables: θ13\theta_{13}, δ\delta, maximal θ23\theta_{23}, the sign of the atmospheric mass difference, satms_{atm}, and the θ23\theta_{23}-octant, socts_{oct}.Comment: 40 pages using epsfig; bibliography modifie

    Determination of plasmid copy number in yeast transformants by means of agarose plugs

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    The determination of plasmid copy number in Saccharomyces cerevisiaetransformants containing circular or linear plasmids is currently performed with total yeast DNA extracts obtained from cultures grown under selection. The determination is based essentially on quantitative Southern hybridization of an appropirate probe to a sequence present both on plasmid and chromosomal DNA in digested or undigested samples run out on conventional agarose gels. The DNA extraction procedure calls for treatment of cell lysates with organic solvents that could entail systemic losses of eithr plasmid or chromosomal DNA thus producing artifactual results. We propose here a method based on the assumption that quantitative analysis of plasmid and chromosomal DNA extracted from yeast cells embedded in agarose plugs will furnish more reliable results. With this procedure the cells are lysed in situ, thus avoiding possible losses of material, and the chromosomes and plasmid DNAs, trapped within the agarose matrix, can be separated by pulse field electrophoresis

    Physics reach of β\beta-beams and ν\nu-factories: the problem of degeneracies

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    We discuss the physics reach of β\beta-Beams and ν\nu-Factories from a theoretical perspective, having as a guideline the problem of degeneracies. The presence of degenerate solutions in the measure of the neutrino oscillation parameters θ13\theta_{13} and δ\delta is, in fact, the main problem that have to be addressed in planning future neutrino oscillation experiments. If degeneracies are not (at least partially) solved, it will be almost impossible to perform, at any future facility, precise measurements of θ13\theta_{13} and/or δ\delta. After a pedagogical introduction on why degenerate solutions arise and how we can get rid of them, we analyze the physics reach of current β\beta-beam and ν\nu-factory configurations. The physics reach of the "standard" \BB is severely affected by degeneracies while a better result can be obtained by higher-γ\gamma setups. At the \NF the combination of Golden and Silver channels can solve the eightfold degeneracy down to sin2θ13103\sin^2\theta_{13} \le 10^{-3}Comment: 5 pages, 6 epsfig; NUFACT'05, 21-26 June 2005, Frascat
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