5,766 research outputs found

    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

    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

    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

    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

    The 2+2 and 3+1 Four-Family Neutrino Mixing at the Neutrino Factory

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    We upgrade the study of the physical reach of a Neutrino Factory in the Four Family Neutrino Mixing scenario taking into account the latest LSND results that points out how the 3+1 scheme cannot be completely ruled out within the present experimental data (although the 2+2 scheme is still the preferred choice when four neutrinos are considered). A detailed comparison of the physical reach of the ν\nu-factory in the two schemes is given, with similar results for the sensitivity to the mixing angles. Huge CP-violating effects can be observed in both schemes with a near, O(10) Km, detector of O(10) Kton size in the νμ→ντ\nu_\mu \to \nu_\tau channel. A smaller detector of 1 Kton size can still observe very large effects in this channel.Comment: 38 Latex2e pages, 21 figures using epsfig, minor change

    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

    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

    Quenched Spectroscopy for the N=1 Super-Yang-Mills Theory

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    We present results for the Quenched SU(2) N=1 Super-Yang-Mills spectrum at β=2.6\beta=2.6, on a V=163×32V=16^3 \times 32 lattice, in the OZI approximation. This is a first step towards the understanding of the chiral limit of lattice N=1 SUSY.Comment: 3 pages, Latex, 2 ps figures, contribution to Lattice 97, Edinburgh 22-26 July 1997; to appear on Nucl. Phys. B. (Proc. Suppl.
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