591 research outputs found
The Interplay Between the "Low" and "High" Energy CP-Violation in Leptogenesis
We analyse within the "flavoured" leptogenesis scenario of baryon asymmetry
generation, the interplay of the "low energy" CP-violation, originating from
the PMNS neutrino mixing matrix , and the "high energy" CP-violation which
can be present in the matrix of neutrino Yukawa couplings, , and can
manifest itself only in "high" energy scale processes. The type I see-saw model
with three heavy right-handed Majorana neutrinos having hierarchical spectrum
is considered. The "orthogonal" parametrisation of the matrix of neutrino
Yukawa couplings, which involves a complex orthogonal matrix , is employed.
In this approach the matrix is the source of "high energy" CP-violation.
Results for normal hierarchical (NH) and inverted hierarchical (IH) light
neutrino mass spectrum are derived in the case of decoupling of the heaviest RH
Majorana neutrino. It is shown that taking into account the contribution to
due to the CP-violating phases in the neutrino mixing matrix can
change drastically the predictions for , obtained assuming only "high
energy" CP-violation from the -matrix is operative in leptogenesis. In the
case of IH spectrum, in particular, there exist significant regions in the
corresponding parameter space where the purely "high energy" contribution in
plays a subdominant role in the production of baryon asymmetry compatible
with the observations.Comment: Results unchanged; comments and references added; version to be
puplished in Eur.Phys.J.
Effects of Lightest Neutrino Mass in Leptogenesis
The effects of the lightest neutrino mass in ``flavoured'' leptogenesis are
investigated in the case when the CP-violation necessary for the generation of
the baryon asymmetry of the Universe is due exclusively to the Dirac and/or
Majorana phases in the neutrino mixing matrix U. The type I see-saw scenario
with three heavy right-handed Majorana neutrinos having hierarchical spectrum
is considered. The ``orthogonal'' parametrisation of the matrix of neutrino
Yukawa couplings, which involves a complex orthogonal matrix R, is employed.
Results for light neutrino mass spectrum with normal and inverted ordering
(hierarchy) are obtained. It is shown, in particular, that if the matrix R is
real and CP-conserving and the lightest neutrino mass m_3 in the case of
inverted hierarchical spectrum lies the interval 5 \times 10^{-4} eV < m_3 < 7
\times 10^{-3} eV, the predicted baryon asymmetry can be larger by a factor of
\sim 100 than the asymmetry corresponding to negligible m_3 \cong 0. As
consequence, we can have successful thermal leptogenesis for 5 \times 10^{-6}
eV < m_3 < 5 \times 10^{-2} eV even if R is real and the only source of
CP-violation in leptogenesis is the Majorana and/or Dirac phase(s) in U.Comment: 28 pages, 6 figures; published versio
Towards Complete Neutrino Mixing Matrix and CP-Violation
The compelling experimental evidences for oscillations of solar, atmospheric
and reactor neutrinos imply the existence of 3-neutrino mixing in vacuum. We
review the phenomenology of 3-neutrino mixing, and the current data on the
3-neutrino mixing parameters. The opened questions and the main goals of future
research in the field of neutrino mixing and oscillations are outlined. A
phenomenological approach for understanding the pattern of neutrino mixing as
an interplay between the mixing, arising from the charged lepton sector, and
bimaximal mixing, arising from a neutrino Majorana mass matrix, is considered
with emphasis on the CP-violating case. We comment also on planned future steps
in the experimental studies of neutrino mixing.Comment: Somewhat extended version (including additional comments, references
and figure) of the invited plenary talk given at the XXIst International
Conference on Neutrino Physics and Astrophysics, June 14-19, 2004, Paris,
France; 10 pages, 4 figure
The Absolute Neutrino Mass Scale, Neutrino Mass Spectrum, Majorana CP-Violation and Neutrinoless Double-Beta Decay
Assuming 3- mixing, massive Majorana neutrinos and neutrinoless
double-beta (\betabeta-) decay generated only by the (V-A) charged current weak
interaction via the exchange of the three Majorana neutrinos, we briefly review
the predictions for the effective Majorana mass \meff in \betabeta-decay and
reanalyse the physics potential of future \betabeta-decay experiments to
provide information on the type of neutrino mass spectrum, the absolute scale
of neutrino masses, and Majorana CP-violation in the lepton sector. Using as
input the most recent experimental results on neutrino oscillation parameters
and the prospective precision that can be achieved in future measurements of
the latter, we perform a statistical analysis of a \betabeta-decay half-life
measurement taking into account experimental and theoretical errors, as well as
the uncertainty implied by the imprecise knowledge of the corresponding nuclear
matrix element (NME). We show, in particular, how the possibility to
discriminate between the different types of neutrino mass spectra and the
constraints on the absolute neutrino mass scale depend on the mean value and
the experimental error of \meff and on the NME uncertainty. The constraints
on Majorana CP-violation phases in the neutrino mixing matrix, which can be
obtained from a measurement of \meff and additional data on the sum of
neutrino masses, are also investigated in detail. We estimate the required
experimental accuracies on both types of measurements, and the required
precision in the NME permitting to address the issue of Majorana CP-violation
in the lepton sector.Comment: 29 pages, 7 figures, minor improvements on the text, fig. 4 improved
graphically, version to appear in Nucl. Phys.
Neutrinoless double-beta decay with three or four neutrino mixing
Considering the scheme with mixing of three neutrinos and a mass hierarchy
that can accommodate the results of solar and atmospheric neutrino experiments,
it is shown that the results of solar neutrino experiments imply a lower bound
for the effective Majorana mass in neutrinoless double-beta decay, under the
natural assumptions that massive neutrinos are Majorana particles and there are
no unlikely fine-tuned cancellations among the contributions of the different
neutrino masses. Considering the four-neutrino schemes that can accommodate
also the results of the LSND experiment, it is shown that only one of them is
compatible with the results of neutrinoless double-beta decay experiments and
with the measurement of the abundances of primordial elements produced in
Big-Bang Nucleosynthesis. It is shown that in this scheme, under the
assumptions that massive neutrinos are Majorana particles and there are no
cancellations among the contributions of the different neutrino masses, the
results of the LSND experiment imply a lower bound for the effective Majorana
mass in neutrinoless double-beta decay.Comment: 18 pages including 2 figures, RevTe
Engineering potent live attenuated coronavirus vaccines by targeted inactivation of the immune evasive viral deubiquitinase
Coronaviruses express a papain-like protease (PLpro) that is required for replicase polyprotein maturation and also serves as a deubiquitinating enzyme (DUB). In this study, using a Middle East respiratory syndrome virus (MERS-CoV) PLpro modified virus in which the DUB is selectively inactivated, we show that the PLpro DUB is an important MERS-CoV interferon antagonist and virulence factor. Although the DUB-negative rMERS-CoVMA replicates robustly in the lungs of human dipeptidyl peptidase 4 knock-in (hDPP4 KI) mice, it does not cause clinical symptoms. Interestingly, a single intranasal vaccination with DUB-negative rMERS-CoVMA induces strong and sustained neutralizing antibody responses and sterilizing immunity after a lethal wt virus challenge. The survival of naive animals also significantly increases when sera from animals vaccinated with the DUB-negative rMERS-CoVMA are passively transferred, prior to receiving a lethal virus dose. These data demonstrate that DUB-negative coronaviruses could be the basis of effective modified live attenuated vaccines.In this work, authors provide a proof-of-concept study showing that deubiquitinating enzyme inactivation in MERS-CoV leads to attenuation in mice, and protection against a lethal challenge.Horizon 2020 (H2020)952373Molecular basis of virus replication, viral pathogenesis and antiviral strategie
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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