Seminars of 2003

Past Seminars


Reconstruction of Supersymmetric High Scale Theories


Dr. Werner Porod

Physik-Institut (Universitaet Zuerich)

Seminari del IFIC

Friday, January 17th, 2003 at 12:00

Abstract

We demonstrate how the fundamental supersymmetric theory at high energy scales can be reconstructed using precision data expected at future high energy collider experiments. We have studied a set of representative examples in this context: minimal supergravity; gauge mediated supersymmetry breaking; and superstring effective field theories.

Constraining neutrino magnetic moment with solar neutrino data


Ms. Maria Amparo Tortola

Instituto de Física Corpuscular

Sala Reuniones Planta Baja del IFIC

Thursday, February 13th, 2003 at 12:00

Abstract

We use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Should such be present, they would contribute to the neutrino-electron scattering cross section and hence alter the signal observed in Super-Kamiokande. At the light of the recent KamLAND result, we assume the LMA-MSW solution to the solar neutrino problem, and we constrain neutrino TMs by using the latest global solar neutrino data. We find that all elements of the TM matrix can be bounded at the same time. Furthermore, we show how reactor data play a complementary role to the solar neutrino data, and use the combination of both data sets to improve the current bounds. Performing a simultaneous fit of LMA-MSW oscillation parameters and TMs we find that 6.3e-10 mu_B and 2.0e-10 mu_B are the 90% C.L. bounds from solar and combined solar + reactor data, respectively. Finally, we perform a simulation of the upcoming Borexino experiment and show that it will improve the bounds from today's data by roughly one order of magnitude.

R-Parity violating decays of the sneutrinos


Dr Diego Restrepo

Inst. Física, Universidad de Antioquia, Colombia

Seminari del IFIC

Friday, January 31st, 2003 at 12:00

Abstract

We consider scenarios of bilinear R-Parity violation where the sneutrino is the LSP. The several sneutrinos can decay dominantly into b-bbar in a wide zone of the parameter space. This gives the possibility to put strong constraints on their masses. Moreover, it may be possible to prove the U_{e3} neutrino mixing directly in e+e- colliders via the R-Parity violating decays of the electronic sneutrinos. Similarly, the atmospheric mixing angle may be proved in
muon colliders through the muonic sneutrino decays. In addition, the invisible decays of the sneutrinos are expected to be sensitive to misalignment origin responsible of the smallness of the neutrino mass.

Leptogenesis and neutrino mass spectra


Liliana Velasco-Sevilla

University of Oxford

Seminari del IFIC

Tuesday, February 18th, 2003 at 16:00

Abstract

I discuss the connection between the phases relevant to leptogenesis and the CP violation phase for neutinos and charged leptons, for two classes of hierarchical neutrino mass matrices. One of these matrices exhibits 'normal' ordering, m1<< m2 <m1>>m3. I also talk about the connections of these phases and the phase responsible for CP violation in neutrinoless double beta decay.

Ultra High Energy Cosmic Rays: a chance for neutrino astronomy


Dr. Gennaro Miele

INFN & University of Naples

Seminari del IFIC

Thursday, February 20th, 2003 at 17:00

Abstract

The new generation of cosmic ray surface detectors are doing to provide a real chance for high-energy neutrino astronomy, which will represent an open window on both astrophysical mechanisms of particle acceleration and
fundamental interactions. The possibility to detect neutrinos in large earth-based apparatus requires the capability of generating reliable simulations of neutrino induced air showers. The recent developments in this direction will be briefly summarized.

Neutrino Factories


Mr. Patrick Huber

Technische Universität München

Sala de Reuniones Planta Baja del IFIC

Tuesday, March 4th, 2003 at 11:00

Abstract

I will give a review on recent developments in the understanding of the physics potential of neutrino factories. Furthermore I will give a comparison of neutrino factories with super-beam experiments.

CP Violation in Neutralino Production


Mr. Olaf Kittel

University of Wuerzburg

Sala Reuniones Planta Baja del IFIC

Wednesday, March 5th, 2003 at 16:00

Abstract

We study CP-violating effects in production and subsequent decay of neutralinos at a linear collider with high luminosity and with longitudinal polarized electron and positron beams in the 500 GeV range. We propose a T-sensitive triple-product asymmetry for the two-body decay of one neutralino into a slepton-lepton pair to measure the CP-sensitive spin component of the neutralino. We work in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters mu and M_1. The CP-violating asymmetries can reach 10%.

Relic neutrinos: recent cosmological bounds on neutrino properties


Dr Sergio Pastor

IFIC

Seminari del IFIC

Friday, April 4th, 2003 at 12:00

Abstract

After a short introduction on the predicted cosmic neutrino background in the Universe, we review some of the cosmological bounds related to neutrinos. In particular we show how the recent data on the anisotropies of the CMBR from the WMAP satellite, combined with other experimental results, can constrain the radiation content of the universal energy density and the sum of neutrino masses.

Ultra High Energy Cosmic Rays


Dr Claudia Isola

Ecole Polytechnique, Paris

Seminari del IFIC

Wednesday, May 7th, 2003 at 12:00

Abstract

For ultrahigh energy cosmic rays with energies above 10^18 eV there are still many open questions as "How can particles be accelerated to these energies?" and "What are their sources?". In addition the newest data from HiRes fluorescence detector, which seem consistent with a GZK cutoff,show a desagrement with the data from the AGASA ground array. In this talk I would like to show the results obtained by numerical simulations under different conditions of source distribution, strenght of extra-galactic magnetic field and nature of primary particles.

Probing Neutrino Parameters at Accelerators


Prof Jorge Romão

Instituto Superior Tecnico and IFIC

Seminari del IFIC

Friday, April 11th, 2003 at 12:00

Abstract

The simplest unified extension of the Minimal Supersymmetric Standard Model with bilinear R-Parity violation provides a predictive scheme for neutrino masses which can account for the observed neutrino properties.Despite the smallness of neutrino masses R-parity violation is observable at present and future high-energy colliders, providing an unambiguous cross-check of the model.

Helioseismic waves in the presence of magnetic fields


Dr. Timur Rashba

IFIC

Seminari del IFIC

Wednesday, April 16th, 2003 at 16:00

Abstract

Significant alteration of the helioseismic g-modes in the presence of radiative zone magnetic fields is discussed. The resulting magneto-gravity wave forms show comparatively sharp spikes which could influence on solar neutrino oscillations.

Phenomenology of Non-Minimal SUSY Models


Dr. Cyril Hugonie

IFIC

Seminari del IFIC

Thursday, May 29th, 2003 at 12:00

Abstract

I will discuss the phenomenology of non-minimal supersymmetric extensions of the Standard Model where a gauge singlet superfield is added in the Higgs sector. First I will give theoretical constraints on the parameter space of the model from the absence of charge and colour breaking minima and cosmologicaly dangerous domain walls. I will also address the possibility of spontaneous CP violation and electroweak baryogenesis. Then I will review experimental constraints from LEP on the (s)particle spectrum and discuss whether at least one Higgs boson will be observed at LHC. I will show in particular that, in some cases, one might have to wait for a LC to give a final answer.

The race for theta_13: Reactor versus Superbeam Neutrino Experiments


Dr. Thomas Schwetz

Technical University Munich

Seminari del IFIC

Tuesday, May 27th, 2003 at 12:30

Abstract

The strong evidences for neutrino oscillations from atmospheric, solar and the KamLAND neutrino experiments
imply that two out of the three leptonic mixing angles are large. For the third mixing angle, theta_{13}, currently only an upper bound from the CHOOZ experiment exits. The next step towards a full understanding of the neutrino sector will be a measurement of this third angle. In this talk the possibility to measure theta_{13} with a future reactor neutrino oscillation experiment consisting of a near and far detector is discussed. Taking into account various systematical errors it is shown that reaching a sensitivity for sin^2 2 theta_{13} down to 0.01 may be possible with such an experiment. This shows that reactor neutrino experiments are highly competitive to the planned first-generation superbeam experiments in testing theta_{13}. On the other hand, due to the complementarity of the two types of experiments a combination of a KamLAND-size reactor experiment with one or two superbeams could substantially improve the ability to obtain information on the type of the neutrino mass hierarchy or the leptonic CP phase.

Mass predictions based on a supersymmetric SU(5) fixed point


Dr. Javier Ferrandis

University of Hawaii

Seminari del IFIC

Monday, June 2nd, 2003 at 12:00

Abstract

I examine the possibility that the third generation fermion masses are determined by the fixed point structure of the minimal supersymmetric SU(5) model. When one-loop supersymmetric thresholds are included, this unified fixed point successfully predicts the top quark mass, 175 +(-) 2 GeV, as well as the weak mixing angle. The bottom quark mass prediction is sensitive to the supersymmetric thresholds; it approaches the measured value for mu <0 and very large unified gaugino mass. The experimental measurement of the tau lepton mass determines tan(beta), and the strong gauge coupling and fine structure constant fix the unification scale and the unified gauge coupling.

A road map to solar neutrino fluxes, neutrino oscillation parameters, and tests for new physics


Dr. Carlos Peña Garay

Institute for Advanced Study, Princeton

Sala Seminarios IFIC (Edf. Institutos Paterna)

Friday, October 3rd, 2003 at 12:00

Abstract

Based upon quantitative analyses of present and simulated future experiments, we answer the question : Why perform low-energy solar neutrino experiments ?

S_3 flavor symmetry and neutrino mixing


Dr Jisuke Kubo

Kanasawa University/Max-Planck Munich

Aula del Cielo A&A (Edf. Paterna first floor)

Thursday, November 6th, 2003 at 12:00

Abstract

We assume that the permutation symmetry based on S_3, the smallest nonabelian group, is an exact flavor symmetry at the weak scale, and extend the standard model in a minimal fashion. We find that S_3 with an additional abeilan discrete symmetry in the leptonic sector allows only six real parameters besides one phase to describe charged lepton and neutrino masses and the neutrino mixing. The model predicts: an inverted spectrum of neutrino mass, the absence of CP violating Dirac phase, theta_{23} is maximal, and theta_{13}=0.034.

Variations on the CMSSM


Mr. Michael Ramage

Universitat de Valencia / University of Oxford

Aula de Seminarios del IFIC (Paterna)

Wednesday, November 12th, 2003 at 12:00

Abstract

I will review the theoretical and experimental constraints that one can impose on the CMSSM in order to restrict the allowed parameter space. I will then go on to discuss how the model might be adapted to incorporate the predictions of a family symmetry and the resulting effects on the low energy phenomenology.

CP Asymmetries in Neutralino Production and Decay


Mr. Olaf Kittel

Universitat de Valencia / University of Wuerzburg

Sala Reuniones Planta Baja del IFIC

Thursday, December 11th, 2003 at 16:00

Abstract

I propose T-odd and CP-odd asymmetries in order to analyze the impact of CP violating phases in neutralino production and subsequent leptonic two-body decays. Numerical results of these asymmetries and of the cross sections will be presented for complex parameters \mu, M_1 and A_\tau. The asymmetries arise on tree level and thus could be large enough to be observed at a linear e+e- collider in the \sqrt{s}=500 GeV range. I discuss the feasibility for measuring the asymmetries by analyzing their statistical errors. Finally, both the asymmetries and the cross sections can be enhanced considerably by using polarized beams.

Leptogenesis and a Jarlskog Invariant


Dr. Sacha Davidson

University of Durham

Aula de Seminaris de Física Teòrica

Wednesday, December 10th, 2003 at 12:00

Abstract

Leptogenesis is an attractive mechanism to generate the matter excess of the Universe. It has the tantalising feature that low energy CP violation among leptons might be related to the baryon asymmetry. However, this is not in general realised, although it can arise in some models. In this talk, I introduce a Jarlskog invariant for the CP violation of leptogenesis. The invariant can be evaluated in terms of left-handed neutrino parameters. The limits in which MNS phases are relevant to leptogenesis can easily be read from this formula.

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