8,922 research outputs found

    νΟ\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(2tan⁡θ232 \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 (θ13−δ\theta_{13}-\delta).Comment: 2 pages, 3 epsfig; NUFACT'05, 21-26 June 2005, Frascat

    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 sin⁡2θ13≤10−3\sin^2\theta_{13} \le 10^{-3}Comment: 5 pages, 6 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

    Quenched Supersymmetry

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    We study the effects of quenching in Super-Yang-Mills theory. While supersymmetry is broken, the lagrangian acquires a new flavour U(1∣1)U(1 \mid 1) symmetry. The anomaly structure thus differs from the unquenched case. We derive the corresponding low-energy effective lagrangian. As a consequence, we predict the mass splitting expected in numerical simulations for particles belonging to the lowest-lying supermultiplet.Comment: LATTICE98(yukawa), minor change

    Degeneracies at a beta-Beam and a Super-Beam Facility

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    The presence of degeneracies can considerably worsen the measure of the neutrino oscillation parameters θ13\theta_{13} and δ\delta. We study the physics reach of a specific ``CERN'' setup, using a standard β\beta-Beam and Super-Beam facility. These facilities have a similar sensitivity in both parameters. Their combination does not provide any dramatic improvement as expected due to their almost identical L/E ratio. We analyse if adding the correspondent disappearance channels can help in reducing the effect of degeneracies in the (θ13,δ)(\theta_{13},\delta) measure.Comment: 5 pages, 7 eps figure

    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

    Physical Reach of a Neutrino Factory in the 2+2 and 3+1 Four-Family Scenario

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    We compare the physical reach of a Neutrino Factory in the 2+2 and 3+1 four-family models, with similar results in the two schemes; in both cases huge CP-violating effects can be observed with a near detector in the νμ→ντ\nu_\mu \to \nu_\tau channel. We also study the capability of long baseline experiments (optimized for the study of the three-family mixing parameter space) in distinguishing a three (active) neutrino model from a four-family scenario.Comment: 5 latex2e pages, 2 figures; talk given at NuFact '01, Tsukuba, 24-30 May 200
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