89 research outputs found
Modeling realistic Earth matter density for CP violation in neutrino oscillation
We examine the effect of a more realistic Earth matter density model which
takes into account of the local density variations along the baseline of a
possi ble 2100 km very long baseline neutrino oscillation experiment. Its
influence to the measurement of CP violation is investigated and a comparison
with the commonly used global density models made. Significant differences are
found in the comparison of the results of the different density models.Comment: 16 pages, 8 figure
Neutral top-pion and lepton flavor violating processes
In the context of topcolor-assisted techicolor(TC2) models, we study the
contributions of the neutral top-pion to the lepton flavor
violating(LFV) processes and .
We find that the present experimental bound on gives severe
constraints on the free parameters of models. Taking into account these
constraints, we consider the processes generated by
top-pion exchange at the tree-level and the one loop level, and obtain
, , in most of
the parameter space.Comment: latex files,16 pages, 6 figures. Submitted to Phys. Rev.
Signal of New Physics and Chemical Composition of Matter in Core Crossing Neutrinos
We consider non-standard matter effect in flavor conversion of neutrinos
crossing the core of the Earth. We show that oscillation of core crossing
neutrinos with E \gsim 0.5 GeV can be well described by a first order
perturbation theory. We show that due to non-standard matter effect varying
chemical composition in the Earth can modify the neutrino flavor conversion by
100%. Effects of CP violating phases in non-standard Neutral Current
interactions are emphasized in particular.Comment: 10 pages, 4 figure
A general analysis with trilinear and bilinear R-parity violating couplings in the light of recent SNO data
We analyse an extension of the minimal supersymmetric standard model
including the dominant trilinear and bilinear R-parity violating contributions.
We take the trilinear terms from the superpotential and the bilinear terms from
the superpotential as well as the scalar potential. We compute the neutrino
masses induced by those couplings and determine the allowed ranges of the
R-parity violating parameters that are consistent with the latest SNO results,
atmospheric data and the Chooz constraint. We also estimate the effective mass
for neutrinoless double beta decay in such scenarios.Comment: 7 pages, Revtex, 1 PS figur
Lenalidomide regulates CNS autoimmunity by promoting M2 macrophages polarization
Multiple sclerosis (MS) is a chronic and debilitating neurological disorder of the central nervous system (CNS), characterized by infiltration of leukocytes into CNS and subsequent demyelination. Emerging evidences have revealed the beneficial roles of M2 macrophages in ameliorating experimental autoimmune encephalomyelitis (EAE), a model for MS. Here, we identify that lenalidomide alone could promote macrophages M2 polarization to prevent the progression of EAE, which is associated with subsequent inhibition of proinflammatory Th1 and Th17 cells both in peripheral lymph system and CNS. Depletion of macrophages by pharmacology treatment of clodronate liposomes or transferring lenalidomide-induced BMDMs in EAE mice completely abolished the therapeutic effect of lenalidomide or prevented EAE development, respectively. The macrophages-derived IL10 was upregulated both in vivo and in vitro after lenalidomide treatment. Moreover, lenalidomide-treated IL10-dificient EAE mice had higher clinical scores and more severe CNS damage, and intravenous injection of lenalidomide-treated IL10BMDMs into mice with EAE at disease onset did not reverse disease severity, implying IL10 may be essential in lenalidomide-ameliorated EAE. Mechanistically, lenalidomide significantly increased expression and autocrine secretion of IL10, subsequently activated STAT3-mediated expression of Ym1. These studies facilitate the development of potential novel therapeutic application of lenalidomide for the treatment of MS
CP violating neutrino oscillation and uncertainties in Earth matter density
We propose a statistical formulation to estimate possible errors in long
baseline neutrino oscillation experiments caused by uncertainties in the Earth
matter density. A quantitative investigation of the effect is made on the CP
asymmetry in future neutrino factory experiments.Comment: Latex, 10 pages, 5 figure
Leptogenesis and rescattering in supersymmetric models
The observed baryon asymmetry of the Universe can be due to the
violating decay of heavy right handed (s)neutrinos. The amount of the asymmetry
depends crucially on their number density. If the (s)neutrinos are generated
thermally, in supersymmetric models there is limited parameter space leading to
enough baryons. For this reason, several alternative mechanisms have been
proposed. We discuss the nonperturbative production of sneutrino quanta by a
direct coupling to the inflaton. This production dominates over the
corresponding creation of neutrinos, and it can easily (i.e. even for a rather
small inflaton-sneutrino coupling) lead to a sufficient baryon asymmetry. We
then study the amplification of MSSM degrees of freedom, via their coupling to
the sneutrinos, during the rescattering phase which follows the nonperturbative
production. This process, which mainly influences the (MSSM) flat
directions, is very efficient as long as the sneutrinos quanta are in the
relativistic regime. The rapid amplification of the light degrees of freedom
may potentially lead to a gravitino problem. We estimate the gravitino
production by means of a perturbative calculation, discussing the regime in
which we expect it to be reliable.Comment: (20 pages, 6 figures), references added, typos corrected. Final
version in revte
Model Independent Information On Solar Neutrino Oscillations
We present the results of a Bayesian analysis of solar neutrino data in terms
of nu_e->nu_{mu,tau} oscillations, independent from the Standard Solar Model
predictions for the solar neutrino fluxes. We show that such a model
independent analysis allows to constraint the values of the neutrino mixing
parameters in limited regions around the usual SMA, LMA, LOW and VO regions.
Furthermore, there is a strong indication in favor of large neutrino mixing and
large values of Delta m^2 (LMA region). We calculate also the allowed ranges of
the neutrino fluxes and we show that they are in good agreement with the
Standard Solar Model prediction. In particular, the ratio of the 8B flux with
its Standard Solar Model prediction is constrained in the interval [0.45,1.42]
with 99.73% probability. Finally, we show that the hypothesis of no neutrino
oscillations is strongly disfavored in a model independent way with respect to
the hypothesis of neutrino oscillations.Comment: 40 pages, 20 figures. Added references and improved figure
Status of four-neutrino mass schemes: a global and unified approach to current neutrino oscillation data
We present a unified global analysis of neutrino oscillation data within the
framework of the four-neutrino mass schemes (3+1) and (2+2). We include all
data from solar and atmospheric neutrino experiments, as well as information
from short-baseline experiments including LSND. If we combine only solar and
atmospheric neutrino data, (3+1) schemes are clearly preferred, whereas
short-baseline data in combination with atmospheric data prefers (2+2) models.
When combining all data in a global analysis the (3+1) mass scheme gives a
slightly better fit than the (2+2) case, though all four-neutrino schemes are
presently acceptable. The LSND result disfavors the three-active neutrino
scenario with only and at 99.9% CL with
respect to the four-neutrino best fit model. We perform a detailed analysis of
the goodness of fit to identify which sub-set of the data is in disagreement
with the best fit solution in a given mass scheme.Comment: 32 pages, 8 Figures included, REVTeX4.Improved discussion in sec. XI,
references added, version accepted by Phys. Rev.
Search for the lepton-family-number nonconserving decay \mu -> e + \gamma
The MEGA experiment, which searched for the muon- and electron-number
violating decay \mu -> e + \gamma, is described. The spectrometer system, the
calibrations, the data taking procedures, the data analysis, and the
sensitivity of the experiment are discussed. The most stringent upper limit on
the branching ratio of \mu -> e + \gamma) < 1.2 x 10^{-11} was obtained
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