3,447 research outputs found
Shifts of neutrino oscillation parameters in reactor antineutrino experiments with non-standard interactions
We discuss reactor antineutrino oscillations with non-standard interactions
(NSIs) at the neutrino production and detection processes. The neutrino
oscillation probability is calculated with a parametrization of the NSI
parameters by splitting them into the averages and differences of the
production and detection processes respectively. The average parts induce
constant shifts of the neutrino mixing angles from their true values, and the
difference parts can generate the energy (and baseline) dependent corrections
to the initial mass-squared differences. We stress that only the shifts of
mass-squared differences are measurable in reactor antineutrino experiments.
Taking Jiangmen Underground Neutrino Observatory (JUNO) as an example, we
analyze how NSIs influence the standard neutrino measurements and to what
extent we can constrain the NSI parameters.Comment: a typo in Eq.(25) fixed after published version, discussion and
conclusion unchange
Constraining Leptonic Flavour Model Parameters at Colliders and Beyond
The observed pattern of mixing in the neutrino sector may be explained by the
presence of a non-Abelian, discrete flavour symmetry broken into residual
subgroups at low energies. Many flavour models require the presence of Standard
Model singlet scalars which can promptly decay to charged leptons in a
flavour-violating manner. We constrain the model parameters of a generic
leptonic flavour model using a synergy of experimental data including limits
from charged lepton flavour conversion, an 8 TeV collider analysis and
constraints from the anomalous magnetic moment of the muon. The most powerful
constraints derive from the MEG collaborations' limit on Br and the reinterpretation of an 8 TeV ATLAS search for anomalous
productions of multi-leptonic final states. We quantify the exclusionary power
of each of these experiments and identify regions where the constraints from
collider and MEG experimental data are complementary.Comment: v1: 28 + 9 pages, 8 figures. v2: 30 + 10 pages, 10 figures. v2
consistent with JHEP accepted version where further discussion of results and
several more references were adde
How to interpret a discovery or null result of the decay
The Majorana nature of massive neutrinos will be crucially probed in the
next-generation experiments of the neutrinoless double-beta ()
decay. The effective mass term of this process, , may
be contaminated by new physics. So how to interpret a discovery or null result
of the decay in the foreseeable future is highly nontrivial. In
this paper we introduce a novel three-dimensional description of , which allows us to see its sensitivity to the lightest
neutrino mass and two Majorana phases in a transparent way. We take a look at
to what extent the free parameters of can be well
constrained provided a signal of the decay is observed someday.
To fully explore lepton number violation, all the six effective Majorana mass
terms (for )
are calculated and their lower bounds are illustrated with the two-dimensional
contour figures. The effect of possible new physics on the decay
is also discussed in a model-independent way. We find that the result of
in the normal (or inverted) neutrino mass ordering
case modified by the new physics effect may somewhat mimic that in the inverted
(or normal) mass ordering case in the standard three-flavor scheme. Hence a
proper interpretation of a discovery or null result of the decay
may demand extra information from some other measurements.Comment: 13 pages, 6 figures, Figures and references update
On neutrino mixing in matter and CP and T violation effects in neutrino oscillations
Aspects of 3-neutrino mixing and oscillations in vacuum and in matter with constant density are investigated working with a real form of the neutrino Hamiltonian. We find the (approximate) equalities θm23= θ23and δm=δ, θ23(θm23) and δ (δm) being respectively the atmospheric neutrino mixing angle and the Dirac CP violation phase in vacuum (in matter) of the neutrino mixing matrix, which are shown to represent excellent approximations for the conditions of the T2K (T2HK), T2HKK, NOνA and DUNE neutrino oscillation experiments. A new derivation of the known relation sin 2θm23sin δm=sin 2θ23sin δ is presented and it is used to obtain a correlation between the shifts of θ23and δ due to the matter effect. A derivation of the relation between the rephasing invariants which determine the magnitude of CP and T violating effects in 3-flavour neutrino oscillations in vacuum, JCP, and of the T violating effects in matter with constant density, JmT≡ Jm, reported in [1]withouta proof, is presented. It is shown that the function F which appears in this relation, Jm= JCPF , and whose explicit form was given in [1], coincides with the function ˜F in the similar relation Jm= JCP˜F derived in [2], although F and ˜F are expressed in terms of different sets of neutrino mass and mixing parameters and have completely different forms
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