ArcAdiA

CP violation in neutrino oscillations and new physics

Sat, 28 Feb 2009 23:00:00 GMT

CP violation in neutrino oscillations and new physics Altarelli, Guido; Meloni, Davide 2009-03-01 Nuclear Physics B 809 158-182 We consider future experiments to detect CP violation in neutrino oscillations and discuss how to test that all asymmetries are indeed described in terms of the single leptonic Jarlskog invariant as predicted in the absence of new physics effects.

A simplest A4 model for Tri-Bimaximal neutrino mixing

Wed, 31 Dec 2008 23:00:00 GMT

A simplest A4 model for Tri-Bimaximal neutrino mixing Altarelli, Guido; Meloni, Davide 2009 Journal of Physics G: Nuclear and Particle Physics 36 085005 We present a see-saw A(4) model for Tri-Bimaximal mixing which is based on a very economical flavour symmetry and field content and still possesses all the good features of A(4) models. In particular the charged lepton mass hierarchies are determined by the A(4) x Z(4) flavour symmetry itself without invoking a Froggatt-Nielsen U(1)symmetry. Tri-Bimaximal mixing is exact in leading order while all the mixing angles receive corrections of the same order in next-to-leading approximation. As a consequence the predicted value of theta(13) is within the sensitivity of the experiments which will take data in the near future. The light neutrino spectrum, typical of A(4) see-saw models, with its phenomenological implications, also including leptoproduction, is studied in detail.

Revisiting bimaximal neutrino mixing in a model with S-4 discretesymmetry

Thu, 30 Apr 2009 22:00:00 GMT

Revisiting bimaximal neutrino mixing in a model with S-4 discretesymmetry Altarelli, Guido; Feruglio, Ferruccio; Merlo, Luca 2009-05 Journal of High Energy Physics 020 In view of the fact that the data on neutrino mixing are stillcompatible with a situation where Bimaximal mixing is valid in firstapproximation and it is then corrected by terms of O(lambda(C)) (withlambda(C) being the Cabibbo angle), arising from the diagonalization ofthe charged lepton masses, such that delta sin(2)theta(12) similar tosin theta(13) similar to O(lambda(C)) while delta sin(2)theta(23)similar to O(lambda(2)(C)), we construct a model based on the discretegroup S 4 where those properties are naturally realized. The model issupersymmetric in 4-dimensions and the complete flavour group is S-4 xZ(4) x U(1)(FN), which also allows to reproduce the hierarchy of thecharged lepton spectrum. The only fine tuning needed in the model is toreproduce the small observed value of r = Delta m(sun)(2)/Deltam(atm)(2). Once the relevant parameters are set to accommodate r thenthe spectrum of light neutrinos shows a moderate normal hierarchy andis compatible, within large ambiguities, with the constraints fromleptogenesis as an explanation of the baryon asymmetry in the Universe.

DIS 2009 Concluding Talk: Outlook and Perspective.

Tue, 30 Jun 2009 22:00:00 GMT

DIS 2009 Concluding Talk: Outlook and Perspective. Altarelli, Guido 2009-07 [1-18] I will present here my perception on the status of Deep Inelastic Scattering physics, as I have further developed it during this Workshop, together with a number of comments on the results that have impressed me most during this week. I will emphasize a number of open problems and of critical areas. Finally I conclude with some projections and auspices for the future of the field.

Status of Neutrino Masses and Mixing in 2009

Wed, 31 Dec 2008 23:00:00 GMT

Status of Neutrino Masses and Mixing in 2009 Altarelli, Guido 2009 91-102 We present a very concise summary of the status of our knowledge and understanding of neutrino masses and mixing.

Theoretical Models of Neutrino Mixing: Recent Developments

Wed, 31 Dec 2008 23:00:00 GMT

Theoretical Models of Neutrino Mixing: Recent Developments Altarelli, Guido 2009 377-396 The data on neutrino mixing are at present compatible with Tri-Bimaximal (TB) mixing. If one takes this indication seriously then the models that lead to TB mixing in first approximation are particularly interesting and A4 models are prominent in this list. However, the agreement of TB mixing with the data could still be an accident. We discuss a recent model based on S4 where Bimaximal mixing is instead valid at leading order and the large corrections needed to reproduce the data arise from the diagonalization of charged leptons. The value of $\theta_{13}$ could distinguish between the two alternatives.

Particle Physics at the LHC Start

Sat, 31 Jan 2009 23:00:00 GMT

Particle Physics at the LHC Start Altarelli, Guido 2009-02 1-26 I present a concise review of where we stand in particle physics today. First, I will discuss the status of the Standard Model, its open problems and the expected answers from the LHC. Then I will briefly review the avenues for New Physics that can be revealed by the LHC.