120 research outputs found
Physics potential of the CERN-MEMPHYS neutrino oscillation project
We consider the physics potential of CERN based neutrino oscillation
experiments consisting of a Beta Beam (BB) and a Super Beam (SPL) sending
neutrinos to MEMPHYS, a 440 kt water \v{C}erenkov detector at Frejus, at a
distance of 130 km from CERN. The discovery reach and the
sensitivity to CP violation are investigated, including a detailed discussion
of parameter degeneracies and systematical errors. For SPL sensitivities
similar to the ones of the phase II of the T2K experiment (T2HK) are obtained,
whereas the BB may reach significantly better sensitivities, depending on the
achieved number of total ion decays. The results for the CERN-MEMPHYS
experiments are less affected by systematical uncertainties than T2HK. We point
out that by a combination of data from BB and SPL a measurement with
antineutrinos is not necessary and hence the same physics results can be
obtained within about half of the measurement time compared to one single
experiment. Furthermore, it is shown how including data from atmospheric
neutrinos in the MEMPHYS detector allows to resolve parameter degeneracies and,
in particular, provides sensitivity to the neutrino mass hierarchy and the
octant of .Comment: 32 pages, 17 figures, minor improvements on the text wrt to v2,
version to appear in JHE
Status of three-neutrino oscillations after the SNO-salt data
We perform a global analysis of neutrino oscillation data in the framework of
three neutrinos, including the recent improved measurement of the neutral
current events at SNO. In addition to all current solar neutrino data we take
into account the reactor neutrino data from KamLAND and CHOOZ, the atmospheric
neutrino data from Super-Kamiokande and MACRO, as well as the first spectral
data from the K2K long baseline accelerator experiment. The up-to-date best fit
values and allowed ranges of the three-flavour oscillation parameters are
determined from these data. Furthermore, we discuss in detail the status of the
small parameters alpha = Delta_m^2_Sol / Delta_m^2_Atm and sin^2(theta_13),
which fix the possible strength of CP violating effects in neutrino
oscillations.Comment: 16 pages, LaTeX file using RevTEX4, 10 figures and 1 table included.
The conclusions reached in version 1 regarding the restriction on
sin^2(theta_13) are now corrected, the solar bound is weaker than that from
reactors even after the inclusion of the SNO salt data. In addition the full
data set has now been reanalized using the pull method instead of the
standard chi-square approach. A few references have also been adde
Lepton flavour violating stau decays versus seesaw parameters: correlations and expected number of events for both seesaw type-I and II
In minimal supergravity (mSugra), the neutrino sector is related to the
slepton sector by means of the renormalization group equations. This opens a
door to indirectly test the neutrino sector via measurements at the LHC.
Concretely, for the simplest seesaw type-I, we present the correlations between
seesaw parameters and ratio of stau lepton flavour violating (LFV) branching
ratios. We find some simple, extreme scenarios for the unknown right-handed
parameters, where ratios of LFV rates correlate with neutrino oscillation
parameters. On the other hand, we scan the mSugra parameter space, for both
seesaw type-I and II, to find regions where LFV stau decays can be maximized,
while respecting low-energy experimental bounds. We estimate the expected
number of events at the LHC for a sample luminosity of L = 100 fb^{-1}.Comment: 10 pages, 6 figures, 1 table, to appear in the proceedings of
DISCRETE'08 Symposium on Prospects in the Physics of Discrete Symmetries,
11-16 December 2008, Valencia, Spain; some comments adde
Global fits to neutrino oscillation data
I summarize the determination of neutrino oscillation parameters within the
three-flavor framework from world neutrino oscillation data with date of May
2006, including the first results from the MINOS long-baseline experiment. It
is illustrated how the determination of the leading "solar" and "atmospheric"
parameters, as well as the bound on emerge from an interplay of
various complementary data sets. Furthermore, I discuss possible implications
of sub-leading three-flavor effects in present atmospheric neutrino data
induced by and for the bound on
and non-maximal values of , emphasizing, however, that these
effects are not statistically significant at present. Finally, in view of the
upcoming MiniBooNE results I briefly comment on the problem to reconcile the
LSND signal.Comment: 5 pages, 5 figures, talk presented at the SNOW2006 workshop,
Stockholm, 2-6 May 200
Bayesian global analysis of neutrino oscillation data
We perform a Bayesian analysis of current neutrino oscillation data. When estimating the oscillation parameters we find that the results generally agree with those of the ¬χ² method, with some differences involving s²₂₃ and CP-violating effects. We discuss the additional subtleties caused by the circular nature of the CP-violating phase, and how it is possible to obtain correlation coefficients with s²₂₃. When performing model comparison, we find that there is no significant evidence for any mass ordering, any octant of s²₂₃ or a deviation from maximal mixing, nor the presence of CP-violation
LFV and Dipole Moments in Models with A4 Flavour Symmetry
It is presented an analysis on lepton flavour violating transitions, leptonic
magnetic dipole moments and electric dipole moments in a class of models
characterized by the flavour symmetry A4 x Z3 x U(1)_FN, whose choice is
motivated by the approximate Tri-Bimaximal mixing observed in neutrino
oscillations. A low-energy effective Lagrangian is constructed, where these
effects are dominated by dimension six operators, suppressed by the scale M of
new physics. All the flavour breaking effects are universally described by the
vacuum expectation values of a set of spurions. Two separate cases, a
supersymmetric and a general one, are described. An upper limit on the reactor
angle of a few percent is concluded.Comment: 10 pages, 1 figure. Adapted from a talk given at "DISCRETE'08:
Symposium on Prospects in the Physics of Discrete Symmetries", December 11-16
2008, Valencia, Spai
Combined potential of future long-baseline and reactor experiments
We investigate the determination of neutrino oscillation parameters by
experiments within the next ten years. The potential of conventional beam
experiments (MINOS, ICARUS, OPERA), superbeam experiments (T2K, NOvA), and
reactor experiments (D-CHOOZ) to improve the precision on the ``atmospheric''
parameters , , as well as the sensitivity to
are discussed. Further, we comment on the possibility to
determine the leptonic CP-phase and the neutrino mass hierarchy if
turns out to be large.Comment: 4 pages, 4 figures, Talk given by T.S. at the NOW2004 workshop, Conca
Specchiulla (Otranto, Italy), 11--17 Sept. 200
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