Seminars of 2011


LSND and MiniBooNE anomalies as a signal of heavy sterile neutrinos


Dr. Juan Carlos Helo

USM Viña del Mar, Chile


Sala de Juntas

Wednesday, September 21st, 2011 at 15:00


Abstract

We examine a recently proposed explanation of the LSND and MiniBooNEanomalies, given in terms of a radiatively decaying sterile neutrino N. We check compatibility of this scenario with the existing experimental data on radiative tau-lepton and K-meson decays. We also analyse perspectives to test this radiativelydecaying sterile neutrino model using different K-meson, D-meson and tau-lepton decays.

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Seminars of 2010



Neutralino decaying dark matter


Dr. Diego Restrepo

U Antioquia


Sala de Reuniones del IFIC – 2 planta baja

Monday, January 11th, 2010 at 12:00


Abstract

In supersymmetric models extended with an anomalous $U(1)_H$
different R-parity violating couplings can yield an unstable
neutralino. We show that in this context astrophysical and
cosmological constraints on neutralino decaying dark matter forbid
bilinear R-parity breaking neutralino decays and lead to a class of
purely trilinear R-parity violating scenarios in which the
neutralino is stable on cosmological scales. We have found that
among the resulting models some of them become suitable to explain
the observed anomalies in cosmic-ray electron/positron fluxes.


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Seminars of 2009


Oscillations of Mossbauer neutrinos


Joachim Kopp

Max-Planck-Institut fur Kernphysik, Heidelberg


Sala Seminarios IFIC (Edf. Institutos Paterna)

Thursday, January 8th, 2009 at 16:00


Abstract

Recently, Raghavan has proposed an experiment to study neutrinos emitted and absorbed in recoil-free processes. We discuss the theory of these “Mössbauer neutrinos”, paying special attention to the oscillation phenomenology. In particular, we will show that, in spite of the extremely good energy resolution of the proposed experiment,
Mossbauer neutrinos can oscillate. After giving quantum mechanical arguments to support this statement, we will compute the oscillation probability of Mossbauer neutrinos, including localization and decoherence terms, in a
quantum mechanical wave packet model. We will then proceed to the calculation of the combined rate of Mossbauer neutrino emission, propagation and absorption in the framework of quantum field theory. This approach allows us to avoid making any a priori assumptions on the neutrino wave function, and it can easily describe the various effects that broaden the neutrino emission and absorption lines. Finally, we will also address the unrealistic, but theoretically extremely interesting, case of Mossbauer neutrinos affected only by natural line broadening and not by solid state effects.

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Seminars of 2008


Ettore Majorana, its neutrino legacy and beyond: a genius at work


Salvatore Esposito

Univ. of Naples “Federico II” & INFN


Sala Seminarios IFIC

Friday, October 31st, 2008 at 11:00


Abstract

“In the world there are various categories of scientists: people of secondary or tertiary standing, who do their best but do not go very far. There are also those of high standing, who come to discoveries of great importance. But then there are geniuses like Galileo and Newton. Well, Ettore was one of them. Majorana had what no one else in the world has…” After a brief biographical sketch, in this talk I will focus on some major contributions by Majorana, mostly unknown, aimed at understanding one of the famous statements by Nobel laureate Enrico Fermi about his pupil (reported above).

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Seminars of 2007


The Epoch of Reionization


Fabio Iocco

Kavli Inst. for Particle Astrophysics & Cosmology


Sala Seminarios IFIC

Wednesday, January 10th, 2007 at 12:00


Abstract

I will summarize the observational evidences of the epoch of Reionization, describing the main physical processes which contribute to such a phenomenon and presenting the astrophysical models invoked to explain this epoch. Eventually I will emphasize the connection between different observables and the future possibility to discriminate between different models.

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Seminars of 2006


SUSY Breaking on the Pillow – Gaugino Mediation and Gravitino Dark Matter in an SO(10) Orbifold GUT


Dr. Joern Kersten

DESY


Sala de Juntas IFIC

Tuesday, January 10th, 2006 at 15:00


Abstract

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Seminars of 2005


Supersymmetry breaking as the origin of flavor


Dr. Javier Ferrandis

Lawrence Berkeley National Laboratory


Seminari del IFIC

Wednesday, January 12th, 2005 at 12:00


Abstract

We present an effective flavor model for the radiative generation of fermion masses and mixings based on a SU(5)XU(2) symmetry. We argue that the original source of flavor breaking resides in the supersymmetry breaking sector. Flavor violation would be transmitted radiatively to the fermion Yukawa couplings at low energy through finite supersymmetric threshold corrections. If this is the case one could fit the fermion mass ratios and CKM matrix elements, suppress the dimension five operators which contribute to proton decay, solve the SUSY CP-problem and overcome the present constraints on supersymmetric contributions to flavor changing processes through an approximate radiative alignment between the Yukawa and the soft supersymmetry breaking sector. We will argue that this possibility is supported by recently discovered patterns between dimensionless fermion mass ratios and CKM elements. We present an effective flavor model for the radiative generation of fermion masses and mixings based on a SU(5)xU(2) symmetry. We assume that the original source of flavor breaking resides in the supersymmetry breaking sector. Flavor violation is transmitted radiatively to the fermion Yukawa couplings at low energy through finite supersymmetric threshold corrections. This model can fit the fermion mass ratios and CKM matrix elements, explain the non-observation of proton decay, solve CP-problems and overcome present constraints on susy contributions to flavor changing processes through an approximate radiative alignment between the Yukawa and the soft trilinear sector. The model predicts new relations between dimensionless fermion mass ratios in the three fermion sectors, and the quark mixing angles.

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Seminars of 2004

Invisible Higgs Boson Decays in Spontaneously Broken R-Parity


Prof. Jorge Romão

Instituto Superior Tecnico, Lisboa


Seminari del IFIC

Wednesday, September 8th, 2004 at 15:00


Abstract

The Higgs boson may decay mainly to an invisible mode characterized by missing energy, instead of the Standard Model channels. This is a generic feature of many models where neutrino masses arise from the spontaneous breaking of ungauged lepton number at relatively low scales, such as spontaneously broken R-parity models. Taking these models as framework, we reanalyze this striking suggestion in view
of the recent data on neutrino oscillations that indicate non-zero neutrino masses. We show that, despite the smallness of neutrino masses, the Higgs boson can decay mainly to the invisible Goldstone boson associated to the spontaneous breaking of lepton number.
The search for invisibly decaying Higgs bosons should be taken into account in the planning of future accelerators,
such as the Large Hadron Collider and the Next Linear Collider.

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