Neutrinos and Ultra-High Energy Cosmic Rays
Soft Susy-breaking terms from strings
Introduction to Ultra-High Energy Cosmic Rays (III)
Dark Matter Detection in the Light of Recent Experimental Results
Introduction to Ultra-High Energy Cosmic Rays (II)
Introduction to Ultra-High Energy Cosmic Rays (I)
Exploring Neutrino Mixing angles and Dirac and Majorana CP Violation Phases at GUT Scale
$V_{13}\sineq 0$ and (2) $\tan^2 \theta_{\rm atm}\simeq 1$. The
recent SNO data implies that the solar mixing angle is far from the
maximal value, $\tan^2 \theta_{\rm sol}\simeq 0.37$. From these data,
it may be natural to assume that at GUT scale, the mixing angles would
be such that (1) $$V_{13}=0$ and (2) $\tan^2 \theta_{\rm atm}\simeq
1$. Then, we explore what kind of solar mixing angle would be at the
GUT scale. The model $V_{13}=0$ at GUT scale, the number of parameters
in the neutrino mass matrix is three masses, two mixing angles and two
Majorana phases. At $m_Z$ scale, $V_{13}$ as well as a Dirac phase is
induced by the radiative correction. In particular, we found that
$\sin^22\tilde\theta_{12}\leq \sin^22\theta_{\rm sol}$, where
$\theta_{12}$ and $\theta_{\rm sol}$ are mixing angles at the GUT
scale and at $m_Z$ scale resprctively. This means that if the solar
mixing angle at $m_Z$ scale is really far from maximal, $\tan^2
\theta_{\rm sol}\simeq 0.37$, then the Bi-maximal scheme can not be a
realistic model. We also discuss possible sizes of $V_{13}$ and a
Dirac CP violation phase.We also comment on the relation between the
CP violation phase and phases which appear in leptogenesis.
Supersymmetry in the Next Linear Collider
Neutrino oscillations in dense neutrino media
refractive index is dominated by the neutrinos themselves. Several
previous studies have found numerically that these self-interactions
have the effect of coupling different neutrino modes in such a way as
to synchronize the flavor oscillations which otherwise would depend on
the energy of a given mode. We show a simple explanation for this
baffling phenomenon in analogy to a system of magnetic dipoles which
are coupled by their self-interactions to form one large magnetic
dipole which then precesses coherently in a weak external magnetic
field (analogous to the weak-field Zeeman effect in atoms).
Neutrinos in Cosmology
most restrictive limits on the overall neutrino mass scale comes from
cosmological structure formation arguments in conjunction with
large-scale galaxy surveys. Conversely, the cosmic neutrino mass
density can be constrained by laboratory measurements of the neutrino
mass, for example in the KATRIN experiment, if the cosmic number
density of neutrinos were known. However, it depends on the unknown
cosmic neutrino degeneracy parameters. We show that neutrino
oscillations effectively lead to chemical equilibrium before big-bang
nucleosynthesis (BBN) if the favored LMA solution of the solar
neutrino problem applies. It is supported by the recent SNO
results. In this case the restrictive BBN limit on the chemical
potential of the electron neutrino applies to all flavors and the
cosmic neutrino density is tightly constrained to be within 1% of its
standard value. The primordial neutrino oscillations involve
fascinating non-linear effects due to the neutrino self-potential
which lead to a synchronization of the oscillations of different
modes. It is fascinating that solving the solar neutrino problem with
the LMA solution indirectly provides a number count of the cosmic
neutrino sea. We finally also mention leptogenesis as an important
cosmological role for Majorana neutrino masses in the experimentally
favored regime.
Neutrinos: from experiment to theory
followed by a review of the paradigm of three active neutrinos, and a
discussion of a natural approach to neutrino mass matrices based on
the see-saw mechanism with right-handed neutrino dominance, with some
examples of unified models satisfying these criteria. I also briefly
mention leptogenesis and the idea of a neutrino factory.
Entropy-Area Relations in Field Theory
scalar field in the background of a curved time-independent metric. To
account for the curvature of space, we postulate a position-dependent
cutoff that depends on energy. With this cutoff, we calculate the
scalar contribution in a background anti-de Sitter space, the exterior
of a black hole, and de Sitter space.In all cases, we find results
that can be simply interpreted in terms of local energy and proper
volume, yielding insight into why a theory appears to be holographic.
Variations on the seesaw mechanism
seesaw mechanism is used as the basic ingredient. I put emphasis on
large or maximal neutrino mixing and show how such mixing angles can
be achieved either by radiative corrections or by lepton number
symmetries.
Supersymmetric Sfermion Sector with CP Violating Phases
of 3rd generation scalar fermions. We work in the Minimal
Supersymmetric Standard Model and take the Higgs-higgsino mass
parameter mu and the trilinear scalar coupling parameters A_f
complex. We analyse the dependence on the complex phases of the CP
conserving and CP violating observables.
CP-Matter Interplay and Measuring MNS in Neutrino Oscillations
remaining parameters in the (1-3) sector of the MNS matrix (lepton
flavor mixing matrix). One of the key point is to understand the
structure of CP-matter interplay. Then I focus on the low-energy
option and discuss the issue of parameter ambiguity and its
resolution.
Large lepton flavour violating signals in supersymmetric models at future e+e- colliders
collider within the general MSSM, allowing for the most general flavor
structure. We demonstrate that there is a large region in parameter
space with large signals, while being consistent with present
experimental bounds on rare lepton decays such as mu -> e gamma. In
our analysis, we include all possible signals from charged slepton and
sneutrino production and their decays as well as from the decays of
neutralinos and charginos. We also consider the background from the
Standard Model and the MSSM. We find that in general the signature e
tau + missing energy is the most pronounced one.
A simple connection between neutrino oscillation and leptogenesis
triplets in left-right symmetric theories. The contribution from the
left-handed Higgs triplet to the see-saw formula can dominate over the
conventional one when the neutrino Dirac mass matrix is identified
with the charged lepton or down quark mass matrix. In this case an
analytic calculation of the lepton asymmetry, generated by the decay
of the lightest right-handed Majorana neutrino, is possible. For
typical parameters, the out-of-equilibrium condition for the decay is
automatically fulfilled. The baryon asymmetry has the correct order of
magnitude, as long as the lightest mass eigenstate is not much lighter
then 10^{-6} to 10^{-8} eV, depending on the solution of the solar
neutrino problem. A sizable signal in neutrinoless double beta decay
can be expected, as long as the smallest mass eigenstate is not much
lighter than 10^{-3} eV and the Dirac mass matrix is identified with
the charged lepton mass matrix.
Introduction to Ultra-High Energy Cosmic Rays (IV)
Wave Packet Treatment of Neutrino Oscillations
Ruling out four-neutrino oscillation interpretations of the LSND anomaly?
Bulk neutrinos and core cooling in Supernovae
with bulk fermions in the context of supernova physics. Following
the usual energy loss argument, the core cooling strongly constraints
the size of such extra dimensions and the mixing parameters. We show
that these constraints can be widely relaxed due to a feedback mechanism
that self-limits the loss. This mechanism also affects the protoneutron
star evolution through a non trivial interplay with neutrino diffusion.
Finally, we discuss the consistency with the SN1987A signal and possible
effects on the neutrino flux composition and the delayed explosion
scenario.
Confronting spin flavor solutions of the solar neutrino problem with current and future solar neutrino data
Leptogenesis via hidden sector: unifying the visible and dark matters
provide a natural candidate for dark matter. Phenomenological and astrophysical implications of such a scenario is discussed.
Leptogenesis from the bottom-up
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See also the IFIC - CSIC/UVEG seminar list
See also the IFIC - CSIC/UVEG seminar list