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.
A three-parameter model for the neutrino mass matrix
Prof. Walter Grimus
Univ Viena
Sala Juntas IFIC (Edf. Institutos Paterna)
Friday, January 12th, 2007 at 12:00
Abstract
Using the type-II seesaw mechanism with three Higgs doublets phi_alpha (alpha = e, mu, tau) and four Higgs triplets, we build a model for lepton mixing based on a 384-element horizontal symmetry group, generated by the permutation group S_3 and by six Z_2 transformations. The charged-lepton mass matrix is diagonal; the symmetries of the model would require all the three masses m_alpha to be equal, but different vacuum expectation values of the phi_alpha allow the m_alpha to split. The number of parameters in the Majorana neutrino mass matrix m_nu depends on two options: full breaking of the permutation group S_3, or leaving a mu–tau interchange symmetry intact; and hard or spontaneous violation of CP. We discuss in detail the case with the minimal number of three parameters, wherein m_nu is real, symmetric under mu–tau interchange, and has equal diagonal elements. In that case, CP is conserved in lepton mixing, atmospheric neutrino mixing is maximal, and theta_{13} = 0; moreover, the type of neutrino mass spectrum and the absolute neutrino mass scale are sensitive functions of the solar mixing angle.
Fermion masses in E6 with S3 permutation symmetry
Dr. Stefano Morisi
University of Milan
Sala Juntas IFIC (Edf. Institutos Paterna)
Friday, January 26th, 2007 at 12:00
Abstract
So far neutrino oscillations are one of the most important signal of new physics. Neutrino data could be nicely explained assuming discrete flavor symmetry between families like the permutation symmetry S3. Such symmetry
is not manifest in the quark sector. Assuming E6 as unified gauge group it is possible to make a distinction between neutrino and charged fermions.
Current Status of Cosmological Inflation
Julien Lesgourgues
LAPTH Annecy
Sala Seminarios IFIC
Tuesday, February 6th, 2007 at 12:30
Abstract
Cosmological inflation is a successful paradigm providing self-consistent initial conditions to the standard cosmological scenario, and explaining the generation of primordial cosmological perturbations. I will recall the main motivations for inflation and explain why current observations provide some indirect –but rather convincing– evidence in favor of inflation. Finally, I will present some up-to-date constraints on various inflationary models.
Flavour Matters in Leptogenesis
Dr. Sacha Davidson
CNRS/Université Lyon 1
Sala Seminarios IFIC (Edf. Institutos Paterna)
Friday, February 9th, 2007 at 12:00
Abstract
Thermal leptogenesis is an attractive mechanism to generate the matter we are made of. In the hot early Universe, a lepton asymmetry is produced by the interactions of a very heavy ( $M \sim 10^9$ GeV) singlet neutrino, and then reprocessed, by non-perturbative Standard Model interactions, into a baryon asymmetry. The dynamics of producing an asymmetry in total lepton number has been carefully studied in the past. I will argue that it is important to follow the evolution of the three (or two) flavoured lepton asymmetries. This generically enhances the predicted baryon asymmetry, because more CP violation is allowed and washout is reduced. The “leptogenesis bound” on the light neutrino mass scale disappears.
Test of lepton flavour violation at LHC
Dr. Thomas Kernreiter
U. Vienna
Sala Juntas IFIC (Edf. Institutos Paterna)
Wednesday, February 28th, 2007 at 12:00
Abstract
We study lepton flavour violating decays of neutralinos
and sleptons within the Minimal Supersymmetric Standard Model.
Taking into account the most recent bounds on flavour violating rare
lepton decays, we study the impact of the lepton flavour violating
neutralino and slepton decays on the di-lepton mass distributions
measured at LHC. We find that they can result in novel and characteristic
edge structures in the distributions, which provides a powerful test of
supersymmetric lepton flavour violation at LHC.
Model for fermion masses and lepton mixing in SO(10)xA4
Dr. Stefano Morisi
University of Milan
Sala de Juntas IFIC
Thursday, April 12th, 2007 at 15:00
Abstract
The discrete flavor symmetry A4 explains very well neutrino data, but it seems difficult to extend this flavor symmetry
to grand unified models since in general left-handed and right-handed fields belong to different A4 representations. Recently it has been proposed a model where all the fermions equally transform under A4. We study an SO(10) realization of such a model giving a seesaw realization for neutrino masses. We fit fermion mass hierarchies. Our model predict the absolute value of the neutrino masses to be 0.052eV, and lepton mixing angles are consequence of the A4 properties.
Large-scale cosmological magnetic fields and magnetic helicity
Prof. Victor Semikoz
Izmiran
Sala Seminarios IFIC (Edf. Institutos Paterna)
Monday, April 23rd, 2007 at 12:00
Abstract
The role of cosmological magnetic field and cosmological magnetic helicity in astrophysics is considered.
We discuss possible mechanisms for cosmological magnetic field production in the early universe as well as upper observationl estimate for such field. In particular, primordial magnetic field generation driven by weak interaction of charged leptons with neutrinos is an efficent way for production of large-scale fields. The general conclusion is that the substantial cosmological field with a non-vanishing helicity can be generated in the early universe and survive up to the epoch of galaxy formation.
Multi-GeV neutrinos due to neutron anti-neutron oscillation in Gamma-Ray Burst Fireballs
Dr. Sarira Sahu
Instituto de Ciencias Nucleares UNAM Mexico
Sala de Juntas del IFIC Paterna
Wednesday, July 18th, 2007 at 12:00
Abstract
The long and short gamma-ray bursts are believed to be produced due to
collapse of massive stars and merger of compact binaries respectively. All these
objects are rich in neutron and the jet outflow from these objects must have a
neutron component in it. By postulating the neutron anti-neutron oscillation in
the gamma-ray burst fireball, we show that, 19-38 GeV neutrinos and
anti-neutrinos can be produced due to annihilation of anti-neutrons with the
background neutrons. These neutrinos and anti-neutrinos will be produced before
the 5-10 GeV neutrinos due to dynamical decoupling of neutrons from the rest of
the fireball. Observation of these neutrinos will shed more light on the nature
of the GRB progenitors and also be a unique signature of physics beyond the
standard model. A possible way of detecting these neutrinos in future is also
discussed.
A new insight in the solar core
Dr. Sylvaine Turck-Chieze
SAp/DAPNIA/CEA Saclay
Sala Sótano UVEG (Ed. Institutos)
Wednesday, June 20th, 2007 at 12:00
Abstract
The Sun is a fundamental object for Astrophysics but also for Physics. Permanent efforts are dedicated to this star in order to progress on the dynamical phenomena which act inside stars. Recently a new signal attributed to gravity modes has revealed a probably fast rotation core. Applications of solar activities are numerous: plasma physics, dark matter, general relativity, fundamental constants, Neutrinos, magnetic relationship between Sun and Earth. It is why we are preparing a new project in the framework of ESA Cosmic Vision, called DynaMICCS for revealing most of the mysteries of our star and determining its real role on Earth climate.
Neutrino masses, SUSY breaking and LFV in the triplet seesaw model
Dr. Filipe Joaquim
Padua U. & INFN
Sala Seminarios IFIC (Edf. Institutos Paterna)
Tuesday, June 26th, 2007 at 12:00
Abstract
I will discuss a supersymmetric realization of the triplet seesaw mechanism
where the exchange of heavy SU(2)_W triplet states generates both neutrino
masses and soft supersymmetry breaking terms. This framework turns out to be
highly predictive since it contains only three free parameters connecting
low-energy neutrino parameters, lepton and quark flavour violation,
sparticle and Higgs boson spectra and electroweak symmetry breakdown. We
perform a complete analysis of the parameter space taking into account the
present experimental constraints and considering different types of neutrino
mass spectrum. A special emphasis is given to the particular features of the
sparticle and Higgs spectra and to LFV processes like mu-> e X, mu-> e
conversion in nuclei, tau-> e Y and tau-> mu Y (X = gamma, e e, Y= gamma, e
e, mu mu).
SUSY Search at future colliders and dark matter experiments
Prof. D P Roy
IFIC/TIFR – Mumbai
Sala Seminarios IFIC (Edf. Institutos Paterna)
Monday, July 9th, 2007 at 12:00
Abstract
I discuss the dark matter constraints on the lightest superparticle (LSP) which can be a bino, wino or
Higgsino. I also describe their signatures at future colliders. as well as in Dark matter experiments.
Dark matter constraints from X-ray observations
Signe Riemer-Sørensen
Niels Bohr Institute, U Copenhagen
Sala de Juntas del IFIC Paterna
Tuesday, November 20th, 2007 at 15:30
Abstract
Several dark matter candidates including the sterile neutrino,
specific Kaluza Klein axions and majorons are allowed to decay into
X-rays, with a characteristic signature. I present the results of
searches for such signatures using Chandra X-ray data of dark matter
dominated regions, and the obtained constraints for the dark matter
candidates.
First steps toward Ultra High-Energy Cosmic-Ray Astronomy
Alessandro Cuoco
University of Aarhus, Denmark
Sala de Juntas del IFIC
Thursday, July 26th, 2007 at 12:00
Abstract
The public available data of cosmic ray arrival directions with energies above 40 EeV present a broad maximum in the cumulative two-point autocorrelation function around 25 degrees. The Auger group has also recently reported an analogous feature in their high-energy data set. This has been interpreted as the first imprint of the filamentary pattern of large scale structures (LSS) of matter in the near universe. We analyze this suggestion in light of the clustering properties expected from a catalogue of galaxies of the local universe (redshift z < 0.06) finding that the data reproduce particularly well the clustering properties of the nearby universe within z < 0.02. Our results suggest a relevant role of magnetic fields (possibly including extragalactic ones) and/or possibly some heavy nuclei fraction in the ultra-high energy cosmic rays.
R-Parity Violation: Neutrino Masses and Collider Signals
Prof. Oscar Eboli
Universidade de Sao Paulo
Sala Seminarios IFIC (Edf. Institutos Paterna)
Monday, July 30th, 2007 at 15:30
Abstract
SUSY models with bilinear R parity violation can generate the observed
neutrino masses and mixings. One interesting feature of this scenario is
that the
lightest supersymmetric particle is unstable and its decay can be
observed at high energy colliders, providing a falsifiable test of
the model. We discuss some aspects of the SUSY phenomenology at
colliders in the framework of this model.
R-Parity Violation: Neutrino Masses and Collider Signals
Prof. Oscar Eboli
Universidade de Sao Paulo
Sala Seminarios IFIC (Edf. Institutos Paterna)
Tuesday, January 30th, 2007 at 12:00
Abstract
SUSY models with bilinear R parity violation can generate the observed
neutrino masses and mixings. One interesting feature of this scenario is
that the
lightest supersymmetric particle is unstable and its decay can be
observed at high energy colliders, providing a falsifiable test of
the model. We discuss some aspects of the SUSY phenomenology at
colliders in the framework of this model.
Probing non-standard neutrino interactions with supernova neutrinos.
Andreu Esteban Pretel
AHEP Group – IFIC
Sala de Juntas del IFIC Paterna
Thursday, August 30th, 2007 at 12:00
Abstract
We analyze the possibility of probing non-standard neutrino interactions (NSI, for short) through the detection of neutrinos produced in a future galactic supernova (SN).We consider the effect of NSI on the neutrino propagation through the SN envelope within a three-neutrino framework, paying special attention to the inclusion of NSI-induced resonant conversions, which may take place in the most deleptonised inner layers. We study the possibility of detecting NSI effects in various ways using a Megaton water Cherenkov detector. We find that the nu_e spectrum can exhibit dramatic features due to the internal NSI-induced resonant conversion. This occurs for non-universal NSI strengths of a few per cent, and for very small flavor-changing NSI.
Non-standard neutrino interactions and low energy neutrino experiments
Dr. Omar Miranda
Cinvestav Mexico
Sala de Juntas del IFIC Paterna
Monday, October 22nd, 2007 at 17:00
Abstract
Non-standard interactions (NSI) arise naturally in different models of
physics beyond the Standard Model, and they can have an important
influence in the solar neutrino analysis. In this talk, after a
discussion of the solar neutrino data I will concentrate in present
and future low-energy experiments and their sensitivity to NSI. It
will be shown that these type of experiments could give constraints
that are competitive with other future proposals such as neutrino
factories.
Neutrino magnetic moment, Borexino and unparticle interactions
Dr Marco Picariello
University of Lecce
Sala de Juntas del IFIC Paterna
Friday, December 14th, 2007 at 12:00
Abstract
We verify if Borexino is or will be able to put a limit on the magnetic moment of the neutrino in a standard scenario, on non standard interaction (NSI), and on the coupling between leptons and unparticles.
We fit the Borexino data by including a new term in the cross section, according to the presence of a non zero magnetic moment for the neutrinos, a NSI, or a non zero coupling between leptons and unparticles.
Selectron production at an e- e- linear collider with transversely polarized beams
Prof. Alfred Bartl
U Vienna
Sala Seminarios IFIC (Edf. Institutos Paterna)
Thursday, June 28th, 2007 at 12:00
Abstract
We study selectron production at an e-e- linear collider. With the help of transverse beam polarizations, we define CP sensitive observables in the production process e- e- –> selectron_L selectron_R. This process proceeds via t-channel and u-channel exchange of neutralinos, and is sensitive to CP violation in the neutralino sector. We present numerical results and estimate the significances to which the CP sensitive observables can be measured.
A tight link between baryogenesis and the neutrino mass in SO(10) theories
Dr. Michele Frigerio
Saclay, SPhT
Sala de Juntas del IFIC Paterna
Tuesday, November 27th, 2007 at 12:00
Abstract
The amount of the matter-antimatter asymmetry
produced from leptogenesis depends on light neutrino data
but also on several unknown parameters,
related to the very high energy scale where lepton number is broken.
In SO(10) Grand Unified Theories, leptogenesis models become more
predictive,
but the freedom in the choice of parameters is only partially reduced.
In this talk I will point out that, in a new class of SO(10)
models, one single
coupling induces neutrino masses as well as a lepton and baryon asymmetry.
The asymmetry is in fact proportional to
${\rm Im}[m^*_{11} (m\,m^*\,m)_{11}]$, where $m$ is the light
neutrino mass matrix.
Therefore, this new mechanism
relates baryogenesis directly to low energy neutrino parameters.
Sneutrino cold dark matter, a new analysis: relic abundance
and detection rates
Dr. Nicolao Fornengo
University of Torino & INFN
Sala Seminarios IFIC (Edf. Institutos Paterna)
Thursday, December 13th, 2007 at 12:00
Abstract
A novel and updated analysis of sneutrinos as dark matter
candidates is presented. We first revisit the canonical Minimal
Supersymmetric Standard Model, concluding that sneutrinos are not yet
fully excluded, although only marginally compatible with existing
experimental bounds when they constitute a largely subdominant
component of dark matter. We then discuss supersymmetric models which
include right-handed fields and/or lepton-number violating terms.
Simple versions of the lepton-number-violating models do not lead to
phenomenology different from the standard case when the bounds
arising from the neutrino mass sector are included. On the contrary,
models with right-handed fields, in addition to provide a merchanism
for the generation of the neutrino mass, are perfectly viable: they
predict sneutrinos which are compatible with the current direct
detection sensitivities, both as subdominant and dominant dark matter
components. We then study the indirect detection signals for such
successful models: predictions for antiproton, antideuteron and gamma-
ray fluxes are provided and compared with existing and future
experimental sensitivities. The neutrino flux from the center of the
Earth is also analyzed. We conclude that models where the neutrino
mass is generated via the see-saw mechanism with a TeV scale Majorana
mass are the most interesting for the sneutrino dark matter sector.
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