894 research outputs found

    Linear flavour violation and anomalies in B physics

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    We propose renormalizable models of new physics that can explain various anomalies observed in decays of B-mesons to electron and muon pairs. The new physics states couple to linear combinations of Standard Model fermions, yielding a pattern of flavour violation that gives a consistent fit to the gamut of flavour data. Accidental symmetries prevent contributions to baryon- and lepton-number-violating processes, as well as enforcing a loop suppression of new physics contributions to flavour violating processes. Data require that the new flavour-breaking couplings are largely aligned with the Yukawa couplings of the SM and so we also explore patterns of flavour symmetry breaking giving rise to this structure.Comment: v2: 28 pages, 10 figures. Added two appendices to make the SU(2) structure of the model clearer, and to discuss Z/photon penguin contributions. Updated a bound on Bs mixing, and added references. Conclusions unchanged. Version to appear in JHE

    The bearable compositeness of leptons

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    Partial compositeness as a theory of flavor in the lepton sector is assessed. We begin presenting the first systematic analysis of neutrino mass generation in this context, and identifying the distinctive mass textures. We then update the bounds from charged lepton flavor and CP violating observables. We put forward a U(1)3 × CP symmetry of the composite sector, in order to allow the new physics to be not far above the TeV scale. This hypothesis effectively suppresses the new contributions to the electron EDM and μ → eγ, by far the most constraining observables, and results in a novel pattern of flavor violation and neutrino masses. The CP violation in the elementary-composite mixing is shown to induce a CKM phase of the correct size, as well as order-one phases in the PMNS matrix. We compare with the alternative possibility of introducing multiple scales of compositeness for leptons, that also allow to evade flavor and CP constraints. Finally, we examine violations of lepton flavor universality in B-meson semi-leptonic decays. The neutral-current anomalies can be accommodated, predicting strong correlations among different lepton flavors, with a few channels close to the experimental sensitivity

    Working Technicolor at the LHC

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    In this talk, we will review the possibility to brake the electroweak symmetry in a dynamical way. We present a class of phenomenologically viable Walking Technicolor models, finally we analyze the potential of the Large Hadron Collider to observe signatures from this kind of models

    Flavor in supersymmetry: The hierarchical scenario

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    Naturalness arguments do not forbid the possibility that the first two families of squarks and sleptons are heavier than the rest of the supersymmetric spectrum. In this framework, we study the phenomenology related to the flavor physics and we give bounds on the flavor violating parameters that we compare with the case of nearly degenerate squarks. The peculiar structure of the hierarchical scheme allows us to make definite predictions and suggests also a natural size for the flavor violating parameters

    Composite leptoquarks and anomalies in B-meson decays

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    We attempt to explain recent anomalies in semileptonic BB decays at LHCb via a composite Higgs model, in which both the Higgs and an SU(2)LSU(2)_L-triplet leptoquark arise as pseudo-Goldstone bosons of the strong dynamics. Fermion masses are assumed to be generated via the mechanism of partial compositeness, which largely determines the leptoquark couplings and implies non-universal lepton interactions. The latter are needed to accommodate tensions in the bsμμb \to s \mu \mu dataset and to be consistent with a discrepancy measured at LHCb in the ratio of B+K+μ+μB^+ \to K^+ \mu^+ \mu^- to B+K+e+eB^+ \to K^+ e^+ e^- branching ratios. The data imply that the leptoquark should have a mass of around a TeV. We find that the model is not in conflict with current flavour or direct production bounds, but we identify a few observables for which the new physics contributions are close to current limits and where the leptoquark is likely to show up in future measurements. The leptoquark will be pair-produced at the LHC and decay predominantly to third-generation quarks and leptons, and LHC13 searches will provide further strong bounds.This work has been partially supported by STFC grant ST/L000385/1 and King's College, Cambridge.This is the final published version. It first appeared at http://dx.doi.org/10.1007/JHEP05(2015)00

    New Physics and flavour-violating processes

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    In the first part of this conference contribution, I will review the status of flavour physics in light of the recent anomalies reported in various observables and by different experiments. In the second part, I will briefly discuss possible interpretations of these anomalies in terms of New Physics

    The diphoton anomaly

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    In December 2015, the ATLAS and CMS Collaborations presented results from data taken at the LHC with pp collisions at the center-of-mass energy of √s = 13TeV. In the search for resonances decaying into two photons, both experiments observed a tantalising excess of events at an invariant mass of the photon pair of 750GeV. In this contribution, I will summarise some of the main phenomenological and theoretical aspects of this anomaly in terms of New Physics

    Static and dynamic thermal properties of construction components: A comparison in idealized and experimental conditions using lumped parameter models

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    The U values assumptions for construction components represent a significant source of uncertainty when estimating the energy performance of buildings. This uncertainty affects decision-making processes in multiple ways, from policy making to design of new and refurbished buildings. The correct estimation of both static (e.g. thermal transmittance) and dynamic thermal properties is crucial for quality assurance in building performance assessment. Further, while today many sophisticated simulators are available for building performance modelling, lumped parameter models can help reducing computational time for parametric simulation or optimization and enable inverse estimation of lumped thermal characteristics. A lumped parameter approach for construction components is proposed, for example, by the ISO 52016-1:2017 norm, introducing simplifications that are intrinsically dependent on component's stratigraphy. This approach complements ISO 13786:2017 norm method, which is limited to steady-state periodic temperature and heat flux boundary conditions. In this research we consider these two different approaches, detailed and lumped modelling, comparing them first in idealized conditions and then in experimental conditions to analyse the robustness of methods

    An all-glass microfluidic network with integrated amorphous silicon photosensors for on-chip monitoring of enzymatic biochemical assay

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    A lab-on-chip system, integrating an all-glass microfluidics and on-chip optical detection, was developed and tested. The microfluidic network is etched in a glass substrate, which is then sealed with a glass cover by direct bonding. Thin film amorphous silicon photosensors have been fabricated on the sealed microfluidic substrate preventing the contamination of the micro-channels. The microfluidic network is then made accessible by opening inlets and outlets just prior to the use, ensuring the sterility of the device. The entire fabrication process relies on conventional photolithographic microfabrication techniques and is suitable for low-cost mass production of the device. The lab-on-chip system has been tested by implementing a chemiluminescent biochemical reaction. The inner channel walls of the microfluidic network are chemically functionalized with a layer of polymer brushes and horseradish peroxidase is immobilized into the coated channel. The results demonstrate the successful on-chip detection of hydrogen peroxide down to 18 mu M by using luminol and 4-iodophenol as enhancer agent
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