350 research outputs found

    Higgs as a BSM probe

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    One of the most important ways to explore BSM at the LCH Run-2 is to study the properties of the Higgs boson. In order to do so in a consistent and model-independent framework, we introduce a set of pseudo-observables (PO), defined from on-shell amplitudes, characterising the properties of Higgs production and decay processes in generic extensions of the Standard Model with no new particles below the Higgs mass. These PO provide a generalisation of the κ-framework used by the LHC experiments and allow for the systematic inclusion of higher-order QED corrections. Symmetries of the new-physics sector, such as CP invariance and fermion universality imply relations among the PO, that could be tested directly from Higgs data. The further assumption that the Higgs is part of an electroweak doublet allows for the introduction of the linear effective field theory (SMEFT) to describe the effect of new physics at low energy. In this context, PO can be matched to the Wilson coefficients of the SMEFT, providing a way to test experimentally the SMEFT predictions by combining Higgs data with other electroweak processes

    New Physics searches in EW physics

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    In this paper we discuss how LHC measurements of electroweak processes can be very sensitive to new physics. We focus in particular on the highenergy tail of dilepton production and present a general study of the limits in the Standard Model effective field theory which can be obtained from these observables. As an example of the strenght of such limits, we show how they can already put relevant constraints on models addressing the observed deviations from lepton flavour universality in rare B-meson decays

    Composite 2HDM with singlets: a viable dark matter scenario

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    We study the non-minimal composite Higgs model with global symmetry SO(7) broken to SO(5) x SO(2). The model results in a composite Two-Higgs doublet model (2HDM) equipped with two extra singlets, the lightest of which can be a viable dark matter candidate. The model is able to reproduce the correct dark matter relic density both via the usual thermal freeze-out and through late time decay of the heavier singlet. In the case of thermal freeze-out, it is possible to evade current experimental constraints even with the minimum fine tuning allowed by electroweak precision tests

    Stable lepton mass matrices

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    Abstract: We study natural lepton mass matrices, obtained assuming the stability of physical flavour observables with respect to the variations of individual matrix elements. We identify all four possible stable neutrino textures from algebraic conditions on their entries. Two of them turn out to be uniquely associated to specific neutrino mass patterns. We then concentrate on the semi-degenerate pattern, corresponding to an overall neutrino mass scale within the reach of future experiments. In this context we show that i) the neutrino and charged lepton mixings and mass matrices are largely constrained by the requirement of stability, ii) naturalness considerations give a mild preference for the Majorana phase most relevant for neutrinoless double-\u3b2 decay, \u3b1 3c \u3c0/2, and iii) SU(5) unification allows to extend the implications of stability to the down quark sector. The above considerations would benefit from an experimental determination of the PMNS ratio 1aU32/U31 1a, i.e. of the Dirac phase \u3b4. \ua9 2016, The Author(s)

    Measurements and tests on FBK silicon sensors with an optimized electronic design for a CTA camera

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    In October 2013, the Italian Ministry approved the funding of a Research & Development (R&D) study, within the "Progetto Premiale TElescopi CHErenkov made in Italy (TECHE)", devoted to the development of a demonstrator for a camera for the Cherenkov Telescope Array (CTA) consortium. The demonstrator consists of a sensor plane based on the Silicon Photomultiplier (SiPM) technology and on an electronics designed for signal sampling. Preliminary tests on a matrix of sensors produced by the Fondazione Bruno Kessler (FBK-Trento, Italy) and on electronic prototypes produced by SITAEL S.p.A. will be presented. In particular, we used different designs of the electronics in order to optimize the output signals in terms of tail cancellation. This is crucial for applications where a high background is expected, as for the CTA experiment.Comment: 5 pages, 6 figures; Proceedings of the 10th Workshop on Science with the New Generation of High-Energy Gamma-ray experiments (SciNeGHE) - PoS(Scineghe2014)00

    Large theta_13 from a model with broken L_e-L_mu-L_tau symmetry

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    Recent data in the neutrino sector point towards a relatively large value of the reactor angle, incompatible with a vanishing theta_ 13 at about 3 sigma. In order to explain such a result, we propose a SUSY model based on the broken L_e-L_mu-L_tau symmetry, where large deviations from the symmetric limit theta_12 = pi/4, tan(theta_23) \sim O(1) and theta_13 = 0 mainly come from the charged lepton sector. We show that a description of all neutrino data is possible if the charged lepton mass matrix has a special pattern of complex matrix elements.Comment: 9 pages, 2 figures. v2: comments and references added, as published in JHE

    Stable fermion mass matrices and the charged lepton contribution to neutrino mixing

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    We study the general properties of hierarchical fermion mass matrices in which the small eigenvalues are stable with respect to perturbations of the matrix entries and we consider specific applications to the charged lepton contribution to neutrino mixing. In particular, we show that the latter can account for the whole lepton mixing. In this case a value of sin \u3b813 73 me/m\u3bcsin \u3b823 48 0.03, as observed, can be obtained without the need of any fine-tuning, and present data allow to determine the last row of the charged lepton mass matrix with good accuracy. We also consider the case in which the neutrino sector only provides a maximal 12 rotation and show that i) present data provide a 2\u3c3 evidence for a non-vanishing 31 entry of the charged lepton mass matrix and ii) a plausible texture for the latter can account at the same time for the atmospheric mixing angle, the \u3b813angle, and the deviation of the \u3b812angle from \u3c0/2 without fine-tuning or tension with data. Finally, we show that the so-called \u201cinverted order\u201d of the 12 and 23 rotations in the charged lepton sector can be obtained without fine-tuning, up to corrections of order me/m\u3bc. \ua9 2014, The Author(s)

    UFT/leucovorin and oxaliplatin alternated with UFT/leucovorin and irinotecan in metastatic colorectal cancer

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    A total of 41 metastatic colorectal cancer (CRC) patients received tegafur/uracil (UFT)+leucovorin (LV)+oxaliplatin alternated with UFT/LV+irinotecan. The overall response rate was 58.5% (95% confidence interval, 42.2-73.3%), and the median progression-free survival was 8.8 months. There were no grade 4 toxicities; 12 patients (29%) experienced grade 3 diarrhoea. There were no cases of hand-foot syndrome. This alternating regimen seems to be effective and well tolerated in the first-line treatment of patients with metastatic CRC
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