One of the primary objectives of the Deep Underground Neutrino Experiment (DUNE) is to discover the leptonic CP violation and to identify its source. In this context, we study the impact of ...non-standard neutrino interactions (NSIs) on observing the CP violation signal at DUNE. We explore the impact of various parameter degeneracies introduced by non-zero NSI and identify which of these can influence the CP violation sensitivity and CP precision of DUNE, by considering NSI both in data and in theory. In particular, we study how the CP sensitivity of DUNE is affected because of the intrinsic hierarchy degeneracy which occurs when the diagonal NSI parameter ϵee=−1 and δCP=±90°.
A
bstract
The neutrino-electron scattering process is a powerful tool to explore new physics beyond the standard model. Recently the possibility of DUNE Near Detector (ND) to constrain various new ...physics scenarios using this process have been highlighted in the literature. In this work, we consider the most general U(1) model and probe the constraints on the mass and coupling strength of the additional
Z′
from
ν − e
scattering at DUNE ND. The presence of the
Z′
gives rise to extra interference effects. In the context of the general U(1) model, the destructive interference can occur in either neutrino or anti-neutrino channel or for both or none. This opens up the possibilities of getting four different type of signal in the neutrino and ant-neutrino runs of DUNE. We perform the analysis using both the total rate and binned events spectrum. Our results show that in a bin by bin analysis the effect of destructive interference is less compared to the analysis using total rate. We present the bounds on the
m
Z′
− g
X
plane from
ν − e
scattering measurements at DUNE ND and compare these with those obtained from other
ν − e
scattering, COHERENT, and beam dump experiments. We show that the DUNE ND can give the best bound for certain mass ranges of
Z′
.
We study the effect of nonstandard interactions (NSIs) on the propagation of neutrinos through the Earth’s matter and how it affects the hierarchy sensitivity of the DUNE experiment. We emphasize the ...special case when the diagonal NSI parameter εee=−1, nullifying the standard matter effect. We show that if, in addition, CP violation is maximal then this gives rise to an exact intrinsic hierarchy degeneracy in the appearance channel, irrespective of the baseline and energy. Introduction of the off diagonal NSI parameter, εeτ, shifts the position of this degeneracy to a different εee. Moreover the unknown magnitude and phases of the off diagonal NSI parameters can give rise to additional degeneracies. Overall, given the current model independent limits on NSI parameters, the hierarchy sensitivity of DUNE can get seriously impacted. However, a more precise knowledge of the NSI parameters, especially εee, can give rise to an improved sensitivity. Alternatively, if a NSI exists in nature, and still DUNE shows hierarchy sensitivity, certain ranges of the NSI parameters can be excluded. Additionally, we briefly discuss the implications of εee=−1 (in the Earth) on the Mikheyev-Smirnov-Wolfenstein effect in the Sun.
Neutrino oscillation physics has entered the precision era and the potential forthcoming experiments Hyper-Kamiokande (T2HK / T2HKK), Deep Under-ground Neutrino Experiment (DUNE) and The European ...Spallation Source ν-Beam (ESSνSB ) project are expected to strengthen this endeavour in the future. In this paper we perform a comprehensive study of the octant, mass hierarchy and CP discovery sensitivities of T2HK / T2HKK, DUNE and ESSνSB project in their individual capacity. We present a comparative account of the probabilities at the respective baselines and explore in detail the physics issues which can cause the differences in the sensitivities among the various experiments. We also find out the optimal exposure required by these experiments for achieving 5σ hierarchy, octant sensitivity and to discover CP violation at 5σ for 60% values of δCP, stand alone and in conjunction with the on going T2K and NOνA experiments. In addition, we study the hierarchy and CP sensitivities of DUNE and T2HK in combination with ESSνSB.
Results from experiments like LSND and MiniBooNE hint towards the possible presence of an extra eV scale sterile neutrino. The addition of such a neutrino will significantly impact the standard three ...flavor neutrino oscillations. In particular, it can give rise to additional degeneracies due to additional sterile parameters. For an eV scale sterile neutrino, the cosmological constraints dictate that the sterile state is heavier than the three active states. However, for lower masses of sterile neutrinos, the sterile state can be lighter than one and/or more of the three states. In such cases, the mass ordering of the sterile neutrinos also becomes unknown, along with the mass ordering of the active states. In this paper, we explore the mass ordering sensitivity in the presence of a sterile neutrino assuming the mass squared difference |Δ41| to be in the range 10–4 –1 eV2. We study (i) how the ordering of the active states, i.e. the determination of the sign of Δ31 gets affected by the presence of a sterile neutrino in the above mass range, (ii) the possible determination of the sign of Δ41 for Δ41 in the range 10–4 –0.1 eV2. This analysis is done in the context of a liquid argon detector using beam neutrinos traveling a distance of 1300 km and atmospheric neutrinos that propagate through a distance ranging from 10 – 10000 km, allowing resonant matter effects. Apart from presenting separate results from these sources, we also do a combined study and probe the synergy between these two in giving an enhanced sensitivity.
The investigation of conservation/violation of conjugation and parity (CP) symmetry in the leptonic sector is essential to understanding the evolution of the universe. Lorentz invariance and CPT are ...fundamental symmetries of nature. The violation of Lorentz invariance can also lead to CPT violations. The standard three-flavor neutrino oscillation framework presents a scenario for observing the signature of Lorentz invariance and CP violations. This work focuses on the effect of Lorentz invariance-violating parameters on the sensitivity to CP violation. We investigate the sensitivity in two proposed configurations of the upcoming T2HK experiment: (i) one detector each placed at 295 km and 1100 km, and (ii) two identical detectors at 295 km. This study probes the effect of CPT-violating parameters
a
e
μ
,
a
e
τ
,
a
μ
τ
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We study the consequences of invisible decay of neutrinos in the context of the DUNE experiment. We assume that the third mass eigenstate is unstable and decays to a light sterile neutrino ...and a scalar or a pseudo-scalar. We consider DUNE running in 5 years neutrino and 5 years antineutrino mode and a detector volume of 40 kt. We obtain the expected sensitivity on the rest-frame life-time
τ
3
normalized to the mass
m
3
as τ
3
/m
3
>
4
.
50 × 10
−11
s/eV at 90% C.L. for a normal hierarchical mass spectrum. We also find that DUNE can discover neutrino decay for τ
3
/m
3
>
4
.
27 × 10
−11
s/eV at 90% C.L. In addition, for an unstable ν
3
with an illustrative value of τ
3
/m
3
= 1
.
2 × 10
−11
s/eV, the no decay case could get disfavoured at the 3
σ
C.L. At 90% C.L. the expected precision range for this true value is obtained as 1
.
71 × 10
−11
>
τ
3
/m
3
>
9
.
29 × 10
−12
in units of s/eV. We also study the correlation between a non-zero τ
3
/m
3
and standard oscillation parameters and find an interesting correlation in the appearance and disappearance channels with the mixing angle
θ
23
. This alters the octant sensitivity of DUNE, favorably (unfavorably) for true
θ
23
in the lower (higher) octant. The effect of a decaying neutrino does not alter the hierarchy or CP violation discovery sensitivity of DUNE in a discernible way.
A
bstract
We study the physics potential of the long-baseline experiments T2HK, T2HKK and ESS
ν
SB in the context of invisible neutrino decay. We consider normal mass ordering and assume the state
ν
...3
as unstable, decaying into sterile states during the flight and obtain constraints on the neutrino decay lifetime (
τ
3
). We find that T2HK, T2HKK and ESS
ν
SB are sensitive to the decay-rate of
ν
3
for
τ
3
/m
3
≤ 2
.
72 × 10
−
11
s/eV,
τ
3
/m
3
≤ 4
.
36 × 10
−
11
s/eV and
τ
3
/m
3
≤ 2
.
43 × 10
−
11
s/eV respectively at 3
σ
C.L. We compare and contrast the sensitivities of the three experiments and specially investigate the role played by the mixing angle
θ
23
. It is seen that for experiments with flux peak near the second oscillation maxima, the poorer sensitivity to
θ
23
results in weaker constraints on the decay lifetime. Although, T2HKK has one detector close to the second oscillation maxima, having another detector at the first oscillation maxima results in superior sensitivity to decay. In addition, we find a synergy between the two baselines of the T2HKK experiment which helps in giving a better sensitivity to decay for
θ
23
in the higher octant. We discuss the octant sensitivity in presence of decay and show that there is an enhancement in sensitivity which occurs due to the contribution from the survival probability
P
μμ
is more pronounced for the experiments at the second oscillation maxima. We also obtain the combined sensitivity of T2HK+ESS
ν
SB and T2HKK+ESS
ν
SB as
τ
3
/m
3
≤ 4
.
36 × 10
−
11
s/eV and
τ
3
/m
3
≤ 5
.
53 × 10
−
11
s/eV respectively at 3
σ
C.L.
Abstract We construct a neutrino mass model based on the flavour symmetry group A 4 × C 4 × C 6 × C 2 which accommodates a light sterile neutrino in the minimal extended seesaw (MES) scheme. Besides ...the flavour symmetry, we introduce a U(1) gauge symmetry in the sterile sector and also impose CP symmetry. The vacuum alignments of the scalar fields in the model spontaneously break these symmetries and lead to the construction of the fermion mass matrices. With the help of the MES formulas, we extract the light neutrino masses and the mixing observables. In the active neutrino sector, we obtain the TM2 mixing pattern with non-zero reactor angle and broken μ-τ reflection symmetry. We express all the active and the sterile oscillation observables in terms of only four real model parameters. Using this highly constrained scenario we predict sin 2 θ 23 = 0.545 − 0.004 + 0.003 , sin δ = − 0.911 − 0.005 + 0.006 , U e 4 2 = 0.029 − 0.008 + 0.009 , U μ 4 2 = 0.010 − 0.003 + 0.003 and U τ 4 2 = 0.006 − 0.002 + 0.002 $$ {\sin}^2{\theta}_{23}={0.545}_{-0.004}^{+0.003},\sin \delta =-{0.911}_{-0.005}^{+0.006},{\left|{U}_{e4}\right|}^2={0.029}_{-0.008}^{+0.009},{\left|{U}_{\mu 4}\right|}^2={0.010}_{-0.003}^{+0.003}\kern0.5em \mathrm{and}\kern0.5em {\left|{U}_{\tau 4}\right|}^2={0.006}_{-0.002}^{+0.002} $$ which are consistent with the current data.
A
bstract
We study the zero textures of the Yukawa matrices in the minimal extended type-I seesaw (MES) model which can give rise to ∼ eV scale sterile neutrinos. In this model, three right handed ...neutrinos and one extra singlet
S
are added to generate a light sterile neutrino. The light neutrino mass matrix for the active neutrinos,
m
ν
, depends on the Dirac neutrino mass matrix (
M
D
), Majorana neutrino mass matrix (
M
R
) and the mass matrix (
M
S
) coupling the right handed neutrinos and the singlet. The model predicts one of the light neutrino masses to vanish. We systematically investigate the zero textures in
M
D
and observe that maximum five zeros in
M
D
can lead to viable zero textures in
m
ν
. For this study we consider four different forms for
M
R
(one diagonal and three off diagonal) and two different forms of (
M
S
) containing one zero. Remarkably we obtain only two allowed forms of
m
ν
(
m
eτ
= 0 and
m
ττ
= 0) having inverted hierarchical mass spectrum. We re-analyze the phenomenological implications of these two allowed textures of
m
ν
in the light of recent neutrino oscillation data. In the context of the MES model, we also express the low energy mass matrix, the mass of the sterile neutrino and the active-sterile mixing in terms of the parameters of the allowed Yukawa matrices. The MES model leads to some extra correlations which disallow some of the Yukawa textures obtained earlier, even though they give allowed one-zero forms of
m
ν
. We show that the allowed textures in our study can be realized in a simple way in a model based on MES mechanism with a discrete Abelian flavor symmetry group
Z
8
×
Z
2
.
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