1,721,669 research outputs found
Higgs and flavour as doors to new physics
No full textA natural solution to the hierarchy problem of the Fermi scale motivates signals of New Physics at current and near-future experiments. After a critical synthesis of this general motivation, we concentrate our attention on the interplay between LHC searches for new resonances, and precision measurements of both Higgs couplings and flavour violating observables. We do so for i) the Higgs sectors of the NMSSM and MSSM, as paradigmatic examples of theories providing extra scalars, and for ii) CKM-like flavour symmetries, with a focus on (Formula presented.). This article is mainly based on several papers by the author, but it also reviews other recent related results. Its goal is to provide a synthetic, yet comprehensive, orientation on these subjects, at the dawn of several (ATLAS and CMS, LHCb, NA62, etc.) forthcoming experimental results
Flavour physics from an approximate U(2)^3 symmetry
No full textThe approximate U(2)^3 symmetry exhibited by the quark sector of the Standard Model, broken in specific directions dictated by minimality (Minimal U(2)3), can explain the current success of the CKM picture of flavour and CP violation while allowing for large deviations form it at foreseen experiments. On top of this, one can consider all the possible breaking terms appearing in the quark Yukawas (Generic U(2)3), and derive the most relevant bounds on these new parameters. In this extended framework, if needed, one could account for the recently observed CP asymmetry in D → ππ, KK decays, while being consistent with all the other constraints
The neutron EDM vs up and charm flavour violation
No full textWe derive a strong bound on the chromo-electric dipole moment of the charm quark, and we quantify its impact on models that allow for a sizeable flavour violation in the up quark sector. In particular we show how the constraints coming from the charm and up CEDMs limit the size of new physics contributions to direct flavour violation in D decays. We also specialize our analysis to the cases of split-families Supersymmetry and composite Higgs models. The results we expose motivate an increase in experimental sensitivity to fundamental hadronic dipoles, and a further exploration of the SM contribution to both flavour violating D decays and nuclear electric dipole moments
Phenomenology of a U(2)^3 flavour symmetry
No full textThe approximate U(2)^3 symmetry exhibited by the quark sector of the Standard Model, broken in specific directions dictated by minimality, can explain the current success of the CKM picture of flavour and CP violation while allowing for large deviations from it at foreseen experiments. The embedding of this symmetry in specific models also leaves space to satisfy collider and precision bounds without spoiling the naturalness of the theory
Higgs boson properties (theory)
No full textWe provide an overview of the theory motivations for extra Higgs bosons, focussing on models that address the hierarchy problem (Twin Higgs, the MSSM and the NMSSM), and on the reasons why new Higgses could be the first particles seen in these models. We then discuss a phenomenological framework to describe the phenomenology of extra Higgs doublets and/or singlets, that easily maps on the above and other models, and that allows to set a strategy to perform experimental searches. We finally summarise the LHC8 status of these searches, as well as their prospects at the next runs of the LHC. In particular we describe the interplay of the following measurements: i) SM Higgs couplings to other SM particles, ii) SM Higgs self coupling, iii) direct searches for extra Higgses
A light dimuon resonance in B decays?
No full textThe observed deviations from the Standard Model in several processes can be explained in terms of a new vector boson produced on-shell in B meson decays. A mass of 2.5-3 GeV and a total width of 10-20% allow to hide the associated dimuon bump in the poorly known charmonium region, and the large invisible decay width can be interpreted in terms of Dark Matter. This proposal predicts a contribution to the muon anomalous magnetic moment, that could explain the long-standing tension with the Standard Model. It also predicts sizeable invisible decays and a peculiar -dependence of the lepton flavor universality ratios and , that could be tested at the LHCb and Belle-II. This proceeding is based on arXiv:1704.06188, and slightly extends it with comments about Dark Matter
In SUSY with a U(2)3 flavour symmetry
No full textA U(2)^3 flavour symmetry acting on the first two generations of quarks partially explains the hierarchies of the yukawa couplings, and provides a natural embedding for Supersymmetry with heavier first two generations, where collider constraints are not in conflict with the requirement of naturalness and the SUSY CP problem is solved. Within this context a specific pattern of flavour symmetry breaking is considered. The K, Bd and Bs mixing amplitudes show a definite correlation that can resolve existing tensions in the CKM fit, pointing in this way to sbottom and gluino masses below about 1.5 TeV. Potentially sizeable contributions to both indirect and direct CP violation in B decays are allowed, even in the absence of flavour-blind phases. In case some effects are observed, the peculiar pattern in ΔF = 2 and ΔB = 1 observables may allow to distinguish between this and other models
Erratum to: A new look at the theory uncertainty of ε K (Journal of High Energy Physics, (2016), 2016, 9, (83), 10.1007/JHEP09(2016)083)
No full textWe correct here a few typos, which only occured in the latex file of the paper, but not in our notes and calculations. Hence they do not affect any results in our paper. • eq. (3.1) should be replaced by (Formula presented.) eq. (3.11) should be replaced by (Formula presented.) • The signs in some λ2 suppressed terms in the CKM expansions should be corrected: eq. (2.36) should be replaced by (Formula presented.) the second line of eq. (2.37) should be replaced by (Formula presented.) eq. (3.9) should be replaced by (Formula presented.) and eq. (5.2) should be replaced by (Formula presented.)
A new look at the theory uncertainty of ε K
No full textThe observable εK is sensitive to flavor violation at some of the highest scales. While its experimental uncertainty is at the half percent level, the theoretical one is in the ballpark of 15%. We explore the nontrivial dependence of the theory prediction and uncertainty on various conventions, like the phase of the kaon fields. In particular, we show how such a rephasing allows to make the short-distance contribution of the box diagram with two charm quarks, ηcc, purely real. Our results allow to slightly reduce the total theoretical uncertainty of εK, while increasing the relative impact of the imaginary part of the long distance contribution, underlining the need to compute it reliably. We also give updated bounds on the new physics operators that contribute to εK
Colture di cellule vegetali: metodi ed applicazioni
No full textIl volume descrive lo stato dell'arte nell'ambito della coltura in vitro di cellule vegetali sottolinenafdo le problematiche aperte e le metologie usat
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