Chatterjee, S. S., Miranda, O. G., Tortola, M., & Valle, J. W. F. (2022). Nonunitarity of the lepton mixing matrix at the European Spallation Source. Phys. Rev. D, 106(7), 075016–16pp.
Abstract: If neutrinos get mass through the exchange of lepton mediators, as in seesaw schemes, the neutrino appearance probabilities in oscillation experiments are modified due to effective nonunitarity of the lepton mixing matrix. This also leads to new CP phases and an ambiguity in underpinning the “conventional” phase of the three-neutrino paradigm. We study the CP sensitivities of various setups based at the European Spallation Source neutrino super-beam (ESSnuSB) experiment in the presence of nonunitarity. We also examine its potential in constraining the associated new physics parameters. Moreover, we show how the combination of DUNE and ESSnuSB can help further improve the sensitivities on the nonunitarity parameters.
|
Chatterjee, S. S., Pasquini, P., & Valle, J. W. F. (2017). Resolving the atmospheric octant by an improved measurement of the reactor angle. Phys. Rev. D, 96(1), 011303–6pp.
Abstract: Taking into account the current global information on neutrino oscillation parameters we forecast the capabilities of future long-baseline experiments such as DUNE and T2HK in settling the atmospheric octant puzzle. We find that a good measurement of the reactor angle theta(13) plays a key role in fixing the octant of the atmospheric angle theta(23) with such future accelerator neutrino studies.
|
Chatterjee, S. S., Pasquini, P., & Valle, J. W. F. (2017). Probing atmospheric mixing and leptonic CP violation in current and future long baseline oscillation experiments. Phys. Lett. B, 771, 524–531.
Abstract: We perform realistic simulations of the current and future long baseline experiments such as T2K, NOvA, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle 023 as well as the value and sign of the CP phase delta(CP) We do this both in general, as well as within the predictive framework of a previously proposed [1] benchmark theory of neutrino oscillations which tightly correlates theta(23) and delta(CP).
|
Chen, M. C., King, S. F., Medina, O., & Valle, J. W. F. (2024). Quark-lepton mass relations from modular flavor symmetry. J. High Energy Phys., 02(2), 160–28pp.
Abstract: The so-called Golden Mass Relation provides a testable correlation between charged-lepton and down-type quark masses, that arises in certain flavor models that do not rely on Grand Unification. Such models typically involve broken family symmetries. In this work, we demonstrate that realistic fermion mass relations can emerge naturally in modular invariant models, without relying on ad hoc flavon alignments. We provide a model-independent derivation of a class of mass relations that are experimentally testable. These relations are determined by both the Clebsch-Gordan coefficients of the specific finite modular group and the expansion coefficients of its modular forms, thus offering potential probes of modular invariant models. As a detailed example, we present a set of viable mass relations based on the Gamma 4 approximately equal to S4 symmetry, which have calculable deviations from the usual Golden Mass Relation.
|
Chen, P., Centelles Chulia, S., Ding, G. J., Srivastava, R., & Valle, J. W. F. (2019). CP symmetries as guiding posts: revamping tri-bi-maximal mixing. Part I. J. High Energy Phys., 03(3), 036–27pp.
Abstract: We analyze the possible generalized CP symmetries admitted by the Tri-Bi-Maximal (TBM) neutrino mixing. Taking advantage of these symmetries we construct in a systematic way other variants of the standard TBM Ansatz. Depending on the type and number of generalized CP symmetries imposed, we get new mixing matrices, all of which related to the original TBM matrix. One of such revamped TBM variants is the recently discussed mixing matrix of arXiv:1806.03367. We also briefly discuss the phenomenological implications following from these mixing patterns.
|
Chen, P., Centelles Chulia, S., Ding, G. J., Srivastava, R., & Valle, J. W. F. (2019). CP symmetries as guiding posts: Revamping tribimaximal mixing. II. Phys. Rev. D, 100(5), 053001–15pp.
Abstract: In this follow up of arXiv:1812.04663 we analyze the generalized CP symmetries of the charged lepton mass matrix compatible with the complex version of the tribimaximal (TBM) lepton mixing pattern. These symmetries are used to “revamp” the simplest TBM Ansatz in a systematic way. Our generalized patterns share some of the attractive features of the original TBM matrix and are consistent with current oscillation experiments. We also discuss their phenomenological implications both for upcoming neutrino oscillation and neutrinoless double beta decay experiments.
|
Chen, P., Centelles Chulia, S., Ding, G. J., Srivastava, R., & Valle, J. W. F. (2018). Neutrino predictions from generalized CP symmetries of charged leptons. J. High Energy Phys., 07(7), 077–26pp.
Abstract: We study the implications of generalized CP transformations acting on the mass matrices of charged leptons in a model-independent way. Generalized e – mu, e – tau and μ- tau symmetries are considered in detail. In all cases the physical parameters of the lepton mixing matrix, three mixing angles and three CP phases can be expressed in terms of a restricted set of independent “theory parameters” that characterize a given choice of CP transformation. This leads to implications for neutrino oscillations as well as neutrinoless double beta decay experiments.
|
Chen, P., Centelles Chulia, S., Ding, G. J., Srivastava, R., & Valle, J. W. F. (2018). Realistic tribimaximal neutrino mixing. Phys. Rev. D, 98(5), 055019–6pp.
Abstract: We propose a generalized version of the tribimaximal (TBM) ansatz for lepton mixing, leading to a nonzero reactor angle theta(13) and CP violation. The latter is characterized by two CP phases. The Dirac phase, affecting neutrino oscillations, is nearly maximal (delta(CP) similar to +/- pi/2), while the Majorana phase implies narrow allowed ranges for the neutrinoless double beta decay amplitude. The solar angle theta(12) lies nearly at its TBM value, while the atmospheric angle theta(23) has the TBM value for a maximal delta(CP). Neutrino oscillation predictions can be tested in present and upcoming experiments.
|
Chen, P., Ding, G. J., Gonzalez-Canales, F., & Valle, J. W. F. (2016). Classifying CP transformations according to their texture zeros: Theory and implications. Phys. Rev. D, 94(3), 033002–26pp.
Abstract: We provide a classification of generalized CP symmetries preserved by the neutrino mass matrix according to the number of zero entries in the associated transformation matrix. We determine the corresponding constrained form of the lepton mixing matrix, characterized by correlations between the mixing angles and the CP violating phases. We compare with the corresponding restrictions from current neutrino oscillation global fits and show that, in some cases, the Dirac CP phase characterizing oscillations is highly constrained. Implications for current and upcoming long baseline neutrino oscillation experiments T2K, NO nu A, and DUNE, as well as neutrinoless double beta decay experiments are discussed. We also study the cosmological implications of such schemes for leptogenesis.
|
Chen, P., Ding, G. J., Gonzalez-Canales, F., & Valle, J. W. F. (2016). Generalized mu-tau reflection symmetry and leptonic CP violation. Phys. Lett. B, 753, 644–652.
Abstract: We propose a generalized mu-tau reflection symmetry to constrain the lepton flavor mixing parameters. We obtain a new correlation between the atmospheric mixing angle theta(23) and the “Dirac” CP violation phase delta(CP). Only in a specific limit our proposed CP transformation reduces to standard mu-tau reflection, for which theta(23) and delta(CP) are both maximal. The “Majorana” phases are predicted to lie at their CP-conserving values with important implications for the neutrinoless double beta decay rates. We also study the phenomenological implications of our scheme for present and future neutrino oscillation experiments including T2K, NO nu A and DUNE.
|
