207 research outputs found

    "Secret" neutrino interactions

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    We review the information about a potentially strong non-standard four-neutrino interaction that can be obtained from available experimental data. By using LEP results and nucleosynthesis data we find that a contact four-fermion neutrino interaction that involve only left-handed neutrinos or both left-handed and right-handed neutrinos cannot be stronger than the standard weak interactions. A much stronger interaction involving only right-handed neutrinos is still allowed.Comment: 12 pages, 2 figures, latex with ws-p8-50x6-00.cls, Talk presented in "Neutrino Mixing", in honour of Samoil Bilenky's 70th Birthday, Torino, March 199

    Bounding effective operators at the one-loop level: the case of four-fermion neutrino interactions

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    The contributions of non-standard four-neutrino contact interactions to electroweak observables are considered at the one-loop level by using the effective quantum field theory language. The analysis is done in terms of three unknown parameters: the strength of the non-standard neutrino interactions, F , an additional derivative coupling needed to renormalize the divergent contributions that appear when the four-neutrino interactions are used at the loop level and a non-standard non-derivative Z-vÂŻv coupling. Then, the precise measurements of the invisible width of the Z-boson at LEP and the data on the neutrino deep-inelastic scattering yield the result F = (−100±140)GF. Assuming that there are no unnatural cancellations between the contributions of the three effective couplings a much stronger bound is obtained: |F | â‰Č 2GF, which is a factor 200 better than the one obtained in previous analyses based on tree level calculations

    One-loop Effective Lagrangian for a Standard Model with a Heavy Charged Scalar Singlet

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    We study several problems related to the construction and the use of effective Lagrangians by considering an extension of the standard model that includes a heavy scalar singlet coupled to the leptonic doublet. Starting from the full renormalizable model, we build an effective field theory by integrating out the heavy scalar. A local effective Lagrangian (up to operators of dimension six) is obtained by expanding the one-loop effective action in inverse powers of the heavy mass. This is done by matching some Green functions calculated with both the full and the effective theories. Using this simple example we study the renormalization of effective Lagrangians in general and discuss how they can be used to bound new physics. We also discuss the effective Lagrangian after spontaneous symmetry breaking, and the use of the standard model classical equations of motion to rewrite it in different forms. The final effective Lagrangian in the physical basis is well suited to the study of the phenomenology of the model, which we comment on briefly. Finally, as an example of the use of our effective field theory, we consider the leptonic flavour-changing decay of the ZZ boson in the effective theory and compare the results obtained with the full model calculation.Comment: 39 pages + 7 figures (available upon request), LaTeX, CERN-TH.7030/9

    FindPeaks 3.1: a tool for identifying areas of enrichment from massively parallel short-read sequencing technology

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    Summary: Next-generation sequencing can provide insight into protein–DNA association events on a genome-wide scale, and is being applied in an increasing number of applications in genomics and meta-genomics research. However, few software applications are available for interpreting these experiments. We present here an efficient application for use with chromatin-immunoprecipitation (ChIP-Seq) experimental data that includes novel functionality for identifying areas of gene enrichment and transcription factor binding site locations, as well as for estimating DNA fragment size distributions in enriched areas. The FindPeaks application can generate UCSC compatible custom ‘WIG’ track files from aligned-read files for short-read sequencing technology. The software application can be executed on any platform capable of running a Java Runtime Environment. Memory requirements are proportional to the number of sequencing reads analyzed; typically 4 GB permits processing of up to 40 million reads