scholarly journals Octant Degeneracy and Quadrant of Leptonic CPV Phase at Long BaselineνExperiments and Baryogenesis

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Kalpana Bora ◽  
Gayatri Ghosh ◽  
Debajyoti Dutta

In a recent work by us, we have studied how CP violation discovery potential can be improved at long baseline neutrino experiments (LBNE/DUNE), by combining with its ND (near detector) and reactor experiments. In this work, we discuss how this study can be further analysed to resolve entanglement of the quadrant of leptonic CPV phase and octant of atmospheric mixing angleθ23, at LBNEs. The study is done for both NH (normal hierarchy) and IH (inverted hierarchy), HO (higher octant), and LO (lower octant). We show how baryogenesis can enhance the effect of resolving this entanglement and how possible values of the leptonic CP violating phaseδCPcan be predicted in this context. With respect to the latest global fit data of neutrino mixing angles, we predict the values ofδCPfor different cases. In this context we present favoured values ofδCP(δCPrange at ≥2σ) constrained by the latest updated BAU range and also confront our predictions ofδCPwith an up-to-date global analysis of neutrino oscillation data. We find that some region of the favouredδCPparameter space lies within the best fit values aroundδCP≃1.3π–1.4π. A detailed analytic and numerical study of baryogenesis through leptogenesis is performed in this framework within the nonsupersymmetric SO(10)models.

2020 ◽  
Vol 35 (17) ◽  
pp. 2050142
Author(s):  
Monojit Ghosh ◽  
Osamu Yasuda

It was shown that the tension between the mass-squared differences obtained from solar neutrinos and those acquired through KamLAND experiments may be solved by the introduction of a non-standard flavor-dependent interaction (NSI) in neutrino propagation. In this study, we discuss the possibility of testing such a hypothesis using the future long-baseline neutrino experiments T2HKK and DUNE. Assuming that the NSI does not exist, we provide the excluded region within the ([Formula: see text], [Formula: see text]) plane, where [Formula: see text] and [Formula: see text] are the parameters appearing in the solar neutrino analysis conducted with the NSI. We find that the best fit value from the solar neutrino and KamLAND data (global analysis of a particular coupling to quarks) can be tested at more than [Formula: see text] by these two experiments for most of the parameter space.


2019 ◽  
Vol 34 (01) ◽  
pp. 1950005
Author(s):  
Sumit K. Garg

We present a systematic analysis of perturbative Hexagonal (HG) mixing for describing recent global fit neutrino mixing data with normal and inverted hierarchy. The corrections to unperturbed mixing are parametrized in terms of small orthogonal rotations [Formula: see text] with modified PMNS matrix of the forms [Formula: see text]. Here, [Formula: see text] is rotation in [Formula: see text] sector and [Formula: see text] is unperturbed Hexagonal mixing matrix. The detailed numerical investigation of all possible cases is performed with scanning of parameter space using [Formula: see text] approach. We found that the perturbative schemes governed by single rotation are unable to fit the mixing angle data even at [Formula: see text] level. The mixing schemes which involve two rotation matrices only [Formula: see text] are successful in fitting all neutrino mixing angles within [Formula: see text] range for normal hierarchy (NH). However for inverted hierarchy (IH), only [Formula: see text] is most preferable as it can fit all mixing angles at [Formula: see text] level. The remaining perturbative cases are either excluded at [Formula: see text] level or successful in producing mixing angles only at [Formula: see text] level. To study the impact of phase parameter, we also looked into CP violating effects for single rotation case. The predicted value of [Formula: see text] lies in the range [Formula: see text] for [Formula: see text] and [Formula: see text] case with normal (inverted) hierarchy.


Author(s):  
C.R. Das ◽  
Jukka Maalampi ◽  
João Pulido ◽  
Sampsa Vihonen

We study the possibility of determining the octant of the neutrino mixing angle 23, that is, whether 23 > 45 or 23 < 45, in long baseline neutrino experiments. Here we numerically derived the sensitivity limits within which these experiments can determine, by measuring the probability of the ! e transitions, the octant of 23 with a 5 certainty. The interference of the CP violation angle with these limits, as well as the effects of the baseline length and the run-time ratio of neutrino and antineutrino modes of the beam have been analyzed.


2003 ◽  
Vol 18 (22) ◽  
pp. 3909-3920
Author(s):  
K. WHISNANT

Current constraints on neutrino mass and mixing parameters are briefly reviewed, and the prospects for future measurements in long-baseline neutrino experiments are discussed. Parameter degeneracies are a generic problem in the three–neutrino analysis of long-baseline neutrino appearance measurements, and can lead to different inferred values for the neutrino mixing angle θ13 and often mix CP violating and CP conserving solutions. Possible experimental strategies for reducing or eliminating such degeneracies and/or the CP confusion are discussed.


2005 ◽  
Vol 20 (01) ◽  
pp. 1-17 ◽  
Author(s):  
OLGA MENA

We review the present understanding of neutrino masses and mixings, discussing what are the unknowns in the three-family oscillation scenario. Despite the anticipated success coming from the planned long baseline neutrino experiments in unraveling the leptonic mixing sector, there are two important unknowns which may remain obscure: the mixing angle θ13 and the CP-phase δ. The measurement of these two parameters has led us to consider the combination of superbeams and neutrino factories as the key to unveil the neutrino oscillation picture.


Universe ◽  
2018 ◽  
Vol 4 (12) ◽  
pp. 141 ◽  
Author(s):  
Guo-Yuan Huang ◽  
Zhi-Zhong Xing ◽  
Jing-Yu Zhu

The latest global analysis of neutrino oscillation data indicates that the normal neutrino mass ordering is favored over the inverted one at the 3 σ level. The best-fit values of the largest neutrino mixing angle θ 23 and the Dirac CP-violating phase δ are located in the higher octant and the third quadrant, respectively. We show that these experimental trends can be naturally explained by the μ - τ reflection symmetry breaking, triggered by the one-loop renormalization-group equations (RGEs) running from a superhigh energy scale down to the electroweak scale in the framework of the minimal supersymmetric standard model (MSSM). The complete parameter space is numerically explored for both the Majorana and Dirac cases, by allowing the smallest neutrino mass m 1 and the MSSM parameter tan β to vary within their reasonable ranges.


2001 ◽  
Vol 16 (29) ◽  
pp. 1881-1886
Author(s):  
MOHAN NARAYAN ◽  
S. UMA SANKAR

Recently it is advocated that high intensity and low energy (Eν~2 GeV ) neutrino beams should be built to probe the (13) mixing angle ϕ to a level of a few parts in 104. Experiments using such beams will have better signal-to-background ratio in searches for νμ→νe oscillations. We propose that such experiments can also determine the sign of Δ31 even if the beam consists of neutrinos only. By measuring the νμ→νe transitions in two different energy ranges, the effects due to propagation of neutrinos through earth's crust can be isolated and the sign of Δ31 can be determined. If the sensitivity of an experiment to ϕ is ε, then the same experiment is automatically sensitive to matter effects and the sign of Δ31 for values of ϕ≥2ε.


2019 ◽  
Vol 35 (06) ◽  
pp. 2050021
Author(s):  
Mohammad Nizam ◽  
Suman Bharti ◽  
Suprabh Prakash ◽  
Ushak Rahaman ◽  
S. Uma Sankar

The long baseline neutrino experiments, T2K and NO[Formula: see text]A, have taken significant amount of data in each of the four channels: (a) [Formula: see text] disappearance, (b) [Formula: see text] disappearance, (c) [Formula: see text] appearance, and (d) [Formula: see text] appearance. There is a mild tension between the disappearance and the appearance data sets of T2K. A more serious tension exists between the [Formula: see text] appearance data of T2K and the [Formula: see text] appearance data of NO[Formula: see text]A. This tension is significant enough that T2K rules out the best-fit point of NO[Formula: see text]A at 95% confidence level, whereas, NO[Formula: see text]A rules out T2K best-fit point at 90% confidence level. We explain the reason why these tensions arise. We also do a combined fit of T2K and NO[Formula: see text]A data and comment on the results of this fit.


2013 ◽  
Vol 28 (31) ◽  
pp. 1350131 ◽  
Author(s):  
SRINU GOLLU ◽  
K. N. DEEPTHI ◽  
R. MOHANTA

The recent results from Daya Bay and RENO reactor neutrino experiments have firmly established that the smallest reactor mixing angle θ13 is nonvanishing at the 5 σ level, with a relatively large value, i.e. θ13 ≈ 9°. Using the fact that the neutrino mixing matrix can be represented as [Formula: see text], where Ul and Uν result from the diagonalization of the charged lepton and neutrino mass matrices and Pν is a diagonal matrix containing the Majorana phases and assuming the tri-bimaximal (TBM) form for Uν, we investigate the possibility of accounting for the large reactor mixing angle due to the corrections of the charged lepton mixing matrix. The form of Ul is assumed to be that of CKM mixing matrix of the quark sector. We find that with this modification it is possible to accommodate the large observed reactor mixing angle θ13. We also study the implications of such corrections on the other phenomenological observables.


2012 ◽  
Vol 27 (08) ◽  
pp. 1230010 ◽  
Author(s):  
C. MARIANI

In this document we will review the current status of reactor neutrino oscillation experiments and present their physics potentials for measuring the θ13 neutrino mixing angle. The neutrino mixing angle θ13 is currently a high-priority topic in the field of neutrino physics. There are currently three different reactor neutrino experiments, DOUBLE CHOOZ, DAYA BAY and RENO and a few accelerator neutrino experiments searching for neutrino oscillations induced by this angle. A description of the reactor experiments searching for a nonzero value of θ13 is given, along with a discussion of the sensitivities that these experiments can reach in the near future.


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