5,540 research outputs found

    Polarized parton distributions in perturbative QCD

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    We review the main results of next-to-leading order QCD analyses of polarized deep-inelastic scattering data, with special attention to the assessment of theoretical uncertainties.Comment: 4 pages Latex, 1 ps figure. Talk given at NUCLEON '99, Frascati(Italy), June 7-9 199

    Status of the Standard Model at the LHC Start

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    I present a concise review of where we stand in particle physics today. First, I will discuss QCD, then the electroweak sector and finally the motivations and the avenues for new physics beyond the Standard Model.Comment: Plenary Talk at the 5th Italian Workshop on p-p Physics at the LHC. 13 pages, no figure

    Concluding talk: fundamental lessons and challenges from neutrinos

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    We present a concise review of the experimental developments on neutrino mixing and their theoretical implications as presented and discussed at this Conference. The recent data disfavour many models but the surviving ones still span a wide range going from Anarchy (no structure, no symmetry in the neutrino sector) to a maximum of symmetry, as for the models based on discrete non-abelian flavour groups which can be improved following the indications from the recent data.Comment: 20 pages, no figures. Talk given at the Pontecorvo 100 Symposium in honour of Bruno Pontecorvo for the centennial of the birth, Pisa, 18-20 September 2013. arXiv admin note: text overlap with arXiv:1304.5047, arXiv:1111.6421, arXiv:1210.346

    An Overview of Neutrino Mixing

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    We present a concise review of the recent important experimental developments on neutrino mixing (hints for sterile neutrinos, large θ13\theta_{13}, possible non maximal θ23\theta_{23}, approaching sensitivity on δCP\delta_{CP}) and their implications on models of neutrino mixing. The new data disfavour many models but the surviving ones still span a wide range going from Anarchy (no structure, no symmetry in the lepton sector) to a maximum of symmetry, as for the models based on discrete non-abelian flavour groups.Comment: 6 pages, no figures. Talk given at the Fourth Workshop on Theory, Phenomenology and Experiments in Flavour Physics, June 2012, Capri, Ital

    The Standard Electroweak Theory and Beyond

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    1. Introduction, 2. Gauge Theories, 3. The Standard Model of Electroweak Interactions, 4. The Higgs Mechanism, 5. The CKM Matrix, 6. Renormalisation and Higher Order Corrections, 7. Why we do Believe in the Standard Model: Precision Tests, 7.1.Precision Electroweak Data and the Standard Model, 7.2.A More General Analysis of Electroweak Data, 8. Why we do not Believe in the Standard Model, 8.1.Conceptual Problems, 8.2.Hints from Experiment, -8.2.1 Unification of Couplings, -8.2.2 Dark Matter, -8.2.3 Neutrino Masses, -8.2.4 Baryogenesis, 9. Status of the Search for the Higgs and for New Physics, 10.ConclusionComment: 59 pages, 9 figures, Lectures given at the Nathiagali Summer School, Pakistan and the PSI Zuoz Summer School, July - August 200

    A Summary from the Theorist's Point of View

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    1. Introduction - 2. Astrophysics and Cosmology - 3. Neutrino Oscillations - 4. Higgs and New Physics Searches - 5. Flavour Physics and CP Violation - 6. QCD - 7. Heavy Ion Collisions - 8. OutlookComment: 10 pages, Summary talk given at the IVth Rencontres du Vietnam on "Physics at Extreme Energies", Hanoi, July 200

    The crucial problem: the electroweak symmetry breaking

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    1. Why we do Believe in the Standard Model 2. Why we do not Believe in the Standard Model 2.1 Conceptual Problems 2.2 Hints from Experiment 2.2.1 Unification of Couplings 2.2.2 Dark Matter 2.2.3 Neutrino Masses 2.2.4 Baryogenesis 3. Status of the Search for the Higgs and for New Physics 4. ConclusionComment: 16 pages, Talk, XI Rencontres de Blois, Frontiers of Matter, 27 June-3 July 199

    On the Q^2 Dependence of Measured Polarized Structure Funtions

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    We analyse the available data on the polarized asymmetries A1A_1 for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive g1g_1 from A1A_1, and we accurately correct for the scaling violations in order to obtain g1(x,Q2)g_1(x,Q^2) with the same Q2Q^2 for all xx values. The contribution to the Q2Q^2 evolution of a possible large gluon polarized density is also considered. The implications for the Ellis-Jaffe and for the Bjorken sum rules are discussed.Comment: 11 pages (LaTex) + 4 figures (topdrawer, included at the end) CERN-TH 7023/9

    Neutrino Masses and Grand Unification

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    We discuss some models of neutrino masses and mixings in the context of fermion masses in Grand Unified Theories.Comment: Talk, 6th Int. Workshop on TAUP99, 6-10 September 1999, Paris,Franc

    Neutrino Tribimaximal Mixing from A_4 Alone

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    Neutrino tribimaximal mixing is obtained from the breaking of A_4 to Z_3 in the charged-lepton sector and to Z_2 in the neutrino sector. To enforce this conflicting pattern, extra particles and symmetries are usually invoked, often accompanied by nonrenormalizable interactions and even extra dimensions. It is shown here in a specific renormalizable model how A_4 alone will accomplish this, with only the help of lepton number.Comment: 8 pages, no figure, reference correcte
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