arXiv subjects

Marco Ciuchini

Publications and source records attributed to Marco Ciuchini.

24 records · Page 2Linked to original sources

arXiv2013

Electroweak Precision Observables, New Physics and the Nature of a 126 GeV Higgs Boson

We perform the fit of electroweak precision observables within the Standard Model with a 126 GeV Higgs boson, compare the results with the theoretical predictions and discuss the impact of recent experimental and theoretical improvements. We introduce New Physics contributions in a model-independent way and fit for the S, T and U parameters, for the $ε_{1,2,3,b}$ ones, for modified $Zb\bar{b}$ couplings and for a modified Higgs coupling to vector bosons. We point out that composite Higgs models are very strongly constrained. Finally, we compute the bounds on dimension-six operators relevant for the electroweak fit.

hep-ph↗

arXiv2011

Physics Opportunities at the Next Generation of Precision Flavor Physics

Starting with next-generation experiments, flavor physics fully enters the era of precision measurements. The focus shifts from testing the Standard Model to finding and characterizing new physics contributions. We review the opportunities offered by future flavor experiments, discussing the expected sensitivities of the most important measurements. We also present some examples of measurable deviations from the Standard Model in the flavor sector generated in a selection of new physics models, demonstrating the major contribution that precision flavor physics could give to the effort of going beyond the Standard Model.

hep-ph↗

arXiv2011

Theoretical uncertainty in sin 2beta: An update

The source of theoretical uncertainty in the extraction of sin 2beta from the measurement of the golden channel Bd -> J/psi K0 is briefly reviewed. An updated estimate of this uncertainty based on SU(3) flavour symmetry and the measurement of the decay Bd -> J/psi pi0 is also presented.

hep-ph↗

arXiv2010

Opportunities From Precision Flavour Physics

The possible role of precision flavour physics, and particularly of B physics, in the next decade is briefly discussed. Few 2--3$σ$ deviations from the Standard Model found in present $B$ data are reviewed as potential forerunners of new physics signals to be looked for in next-generation experiments. The perspectives for theoretical calculations, in particular those based on lattice QCD, to match the expected progress in experimental precision are also discussed.

hep-ph↗

arXiv2002

A new model-independent way of extracting |V_ub/V_cb|

The ratio between the photon spectrum in B -> X_s gamma and the differential semileptonic rate wrt the hadronic variable M_X/E_X is a short-distance quantity calculable in perturbation theory and independent of the Fermi motion of the b quark in the B meson. We present a NLO analysis of this ratio and show how it can be used to determine |V_ub/V_cb| independently of any model for the shape function. We also discuss how this relation can be used to test the validity of the shape-function theory on the data.

hep-ph↗

arXiv1997

$ε'/ε$: three years later

Three years after the completion of the next-to-leading order calculation, the status of the theoretical estimates of $ε'/ε$ is reviewed. In spite of the theoretical progress, the prediction of $ε'/ε$ is still affected by a 100% theoretical error. In this paper the different sources of uncertainty are critically analysed and an updated estimate of $ε'/ε$ is presented. Some theoretical implications of a value of $ε'/ε$ definitely larger than $10^{-3}$ are also discussed.

hep-ph↗