Articles de revues : « Neutrinole »

1

Khatun, Amina, et Fedor Šimkovic. « Effective Majorana Neutrino Mass for ΔL = 2 Neutrino Oscillations ». Symmetry 14, n^o 7 (5 juillet 2022) : 1383. http://dx.doi.org/10.3390/sym14071383.

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It is well known that the observations of neutrinoless double-beta decay prove the Majorana nature of the neutrino. However, with specific values of Majorana phases, the effective Majorana neutrino mass to be estimated from the observation of neutrinoless double-beta decay experiments is strongly suppressed if the neutrino mass pattern adheres to a normal ordering. In this case, double-beta decay might not be observed even though the neutrino is Majorana in nature. We show if neutrinos oscillate to antineutrinos in their propagation; then, the observation of this oscillation proves that neutrinos are Majorana and will provide a measurement of neutrino masses and Majorana phases.

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Lu, Jianlong, Aik Hui Chan et Choo Hiap Oh. « A Phenomenological Model of Effectively Oscillating Massless Neutrinos and Its Implications ». EPJ Web of Conferences 240 (2020) : 02002. http://dx.doi.org/10.1051/epjconf/202024002002.

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We discuss an alternative picture of neutrino oscillation. In this phenomenological model, the flavor-changing phenomena of massless neutrinos arise from scattering processes between neutrinos and four types of undetected spin-0 massive particles pervading throughout the Universe, instead of neutrinos’ own nature. These scattering processes are kinematically similar to Compton scattering. One type of left-handed massless sterile neutrino is needed in order to reproduce the neutrino oscillation modes predicted in the theory of neutrino mixing. Implications of our model include the existence of sterile neu- trinos, the nonconservation of active neutrinos, the possible mismatch among three neutrino mass squared diﬀerences ∆m2ij interpreted in the theory of neutrino mixing, the spacetime dependence of neutrino oscillation, and the impossibility of neutrinoless double beta decay. Several important open problems in neutrino physics become trivial or less severe in our model, such as the smallness of neutrino masses, neutrino mass hierarchy, the mechanism responsible for neutrino masses, and the Dirac/Majorana nature of neutrinos.

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Faessler, A. « Super-Kamiokande neutrino oscillations and the supersymmetric model ». HNPS Proceedings 9 (11 février 2020) : 14. http://dx.doi.org/10.12681/hnps.2773.

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The standard model predicts a ratio of 2 for the number of atmospheric muon to electron neutrinos, while super-Kamiokande and others measure a much smaller value (1.30±0.02 for super-Kamiokande). Super-Kamiokande is also able to measure roughly the direction and the energy of the neutrinos. The zenith-angle dependence for the muon neutrinos suggests that the muon neutrinos oscillate into a third neutrino species, either into the r neutrino or a sterile neutrino. This finding is inves- tigated within the supersymmetric model. The neutrinos mix with the neutralinos, this meaning the wino, the bino and the two higgsinos. The 7 x 7 mass matrix is calculated on the tree level. One finds that the mass matrix has three linearly dependent rows, which means that two masses are zero. They are identified with the two lightest neutrino masses. The fit of the super-Kamiokande data to oscillations between three neutrinos yields, together with the result of supersymmetry, that the third neutrino mass lies between 2x10^-2 and 10^-1 eV. The two lightest neutrino masses are in supersymmetry on the tree level zero. The averaged electron neutrino mass which is the essential parameter in the neutrinoless double-beta decay is given by {m_ve) ~ m_v3 P_ze < 0.8 x10^-2 eV (95% confidence limit). It is derived from the super-Kamiokande data in this supersymmetric model to be two orders smaller than the best value (1 eV) from the neutrinoless double-beta decay.

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BILENKY, S. M. « NEUTRINOS : A BRIEF REVIEW ». Modern Physics Letters A 19, n^o 33 (30 octobre 2004) : 2451–77. http://dx.doi.org/10.1142/s0217732304015944.

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The major steps in the development of our knowledge about neutrinos are reviewed. The basics of neutrino oscillation formalism is presented. Neutrino oscillations in the framework of three-neutrino mixing are considered. The evidence for neutrino oscillations is discussed. Neutrinoless double β-decay is briefly considered.

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Giunti, Carlo, et Thierry Lasserre. « eV-Scale Sterile Neutrinos ». Annual Review of Nuclear and Particle Science 69, n^o 1 (19 octobre 2019) : 163–90. http://dx.doi.org/10.1146/annurev-nucl-101918-023755.

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We address the phenomenology of light sterile neutrinos, with an emphasis on short-baseline neutrino oscillations. After reviewing the observed short-baseline neutrino oscillation anomalies, we discuss the global fit of the data and the current appearance–disappearance tension. We also review briefly the effects of light sterile neutrinos in β decay, neutrinoless double-β decay, and cosmology. Finally, we discuss future perspectives of the search for the effects of eV-scale sterile neutrinos.

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Verma, Rishu, Monal Kashav, Ankush B, Gazal Sharma, Surender Verma et B. C. Chauhan. « Texture One Zero Model Based on A4 Flavor Symmetry and its Implications to Neutrinoless Double Beta Decay ». Journal of Nuclear Physics, Material Sciences, Radiation and Applications 9, n^o 1 (31 août 2021) : 67–71. http://dx.doi.org/10.15415/jnp.2021.91012.

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Neutrinos are perhaps the most elusive particles in our Universe. Neutrino physics could be counted as a benchmark for various new theories in elementary particle physics and also for the better understanding of the evolution of the Universe. To complete the neutrino picture, the missing information whether it is about their mass or their nature that the neutrinos are Majorana particles could be provided by the observation of a process called neutrinoless double beta (0νββ) decay. Neutrinoless double beta decay is a hypothesised nuclear process in which two neutrons simultaneously decay into protons with no neutrino emission. In this paper we proposed a neutrino mass model based on A4 symmetry group and studied its implications to 0νββ decay. We obtained a lower limit on |Mee| for inverted hierarchy and which can be probed in 0νββ experiments like SuperNEMO and KamLAND-Zen.

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Francis, Ng K., et Ankur Nath. « The Effects of Majorana Phases in Estimating the Masses of Neutrinos ». International Journal of Modern Physics : Conference Series 47 (janvier 2018) : 1860100. http://dx.doi.org/10.1142/s201019451860100x.

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Majorana CP violating phases coming from heavy right-handed Majorana mass matrices([Formula: see text]) are considered to estimate the masses of neutrinos. The effects of phases on quasi-degenerate neutrinos mass matrix obeying [Formula: see text] symmetry predicts the results consistent with observations for (i) solar mixing angle([Formula: see text]) below TBM, (ii) absolute neutrino mass parameters[[Formula: see text]] in neutrinoless double beta([Formula: see text]) decay, and (iii) cosmological upper bound [Formula: see text]. Analysis is carried out through parameterization of light left-handed Majorana neutrino matrices ([Formula: see text]) using only two unknown parameters ([Formula: see text]) within [Formula: see text] symmetry. We consider the charge lepton and up quark matrices as diagonal form of Dirac neutrino mass matrix ([Formula: see text]), and [Formula: see text] are generated using [Formula: see text] through inversion of Type-I seesaw formula. The analysis shows that the masses of neutrinos are in agreement with the upper bound from cosmology and neutrinoless double beta decay. The results presented in this article will have important implications in discriminating the neutrinos mass models.

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8

Kudenko, Yury. « New results and perspectives in neutrino physics ». EPJ Web of Conferences 212 (2019) : 01005. http://dx.doi.org/10.1051/epjconf/201921201005.

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A brief review of new results and perspectives in neutrino physics is presented. An emphasis on a search for CP violation in neutrino oscillations and a search for sterile neutrinos is given. Status of measurement of the direct neutrino mass measurement and searches for neutrinoless double beta decay are also discussed.

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9

Petcov, S. T. « The Nature of Massive Neutrinos ». Advances in High Energy Physics 2013 (2013) : 1–20. http://dx.doi.org/10.1155/2013/852987.

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The compelling experimental evidences for oscillations of solar, reactor, atmospheric, and accelerator neutrinos imply the existence of 3-neutrino mixing in the weak charged lepton current. The current data on the 3-neutrino mixing parameters are summarised and the phenomenology of 3-νmixing is reviewed. The properties of massive Majorana neutrinos and of their various possible couplings are discussed in detail. Two models of neutrino mass generation with massive Majorana neutrinos—the type I see-saw and the Higgs triplet model—are briefly reviewed. The problem of determining the nature, Dirac or Majorana, of massive neutrinos is considered. The predictions for the effective Majorana mass|〈m〉|in neutrinoless double-beta-((ββ)0ν-) decay in the case of 3-neutrino mixing and massive Majorana neutrinos are summarised. The physics potential of the experiments, searching for(ββ)0ν-decay for providing information on the type of the neutrino mass spectrum, on the absolute scale of neutrino masses, and on the Majorana CP-violation phases in the PMNS neutrino mixing matrix, is also briefly discussed. The opened questions and the main goals of future research in the field of neutrino physics are outlined.

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10

Okada, Nobuchika, et Osamu Yasuda. « A Sterile Neutrino Scenario Constrained By Experiments and Cosmology ». International Journal of Modern Physics A 12, n^o 21 (20 août 1997) : 3669–94. http://dx.doi.org/10.1142/s0217751x97001894.

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We analyze a scheme in which three active neutrinos and one sterile neutrino account for the solar, the atmospheric and the LSND neutrino anomalies in a model-independent way. It is shown that if the equivalent number, Nν, of the light neutrino species is less than 4, then the constraints from these anomalies, accelerator and reactor experiments and big bang nucleosynthesis force a general 4 × 4 mixing matrix to be effectively split into two 2 × 2 matrices. If these neutrinos are of the Majorana type, then negative results of neutrinoless double beta decay experiments imply that the total mass of neutrinos is not sufficient to account for all the hot dark matter components.

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11

DEV, S., et SANJEEV KUMAR. « NEUTRINO PARAMETER SPACE FOR A VANISHING ee ELEMENT IN THE NEUTRINO MASS MATRIX ». Modern Physics Letters A 22, n^o 19 (21 juin 2007) : 1401–10. http://dx.doi.org/10.1142/s0217732307021767.

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The consequences of a texture zero at the ee entry of neutrino mass matrix in the flavor basis, which also implies a vanishing effective Majorana mass for neutrinoless double beta decay, have been studied for Majorana neutrinos. The neutrino parameter space under this condition has been constrained in the light of all available neutrino data including the CHOOZ bound on [Formula: see text].

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12

CHAKRABORTTY, JOYDEEP, MOUMITA DAS et SUBHENDRA MOHANTY. « CONSTRAINTS ON TeV SCALE MAJORANA NEUTRINO PHENOMENOLOGY FROM THE VACUUM STABILITY OF THE HIGGS ». Modern Physics Letters A 28, n^o 11 (10 avril 2013) : 1350032. http://dx.doi.org/10.1142/s0217732313500326.

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The vacuum stability condition of the Standard Model (SM) Higgs potential with mass in the range of 124–127 GeV puts an upper bound on the Dirac mass of the neutrinos. We study this constraint with the right-handed neutrino masses up to TeV scale. The heavy neutrinos contribute to ΔL = 2 processes like neutrinoless double beta decay and same-sign-dilepton (SSD) production in the colliders. The vacuum stability criterion also restricts the light-heavy neutrino mixing and constrains the branching ratio (BR) of lepton flavor-violating process, like μ→eγ mediated by the heavy neutrinos. We show that neutrinoless double beta decay with a lifetime ~1025 years can be observed if the lightest heavy neutrino mass is <4.5 TeV. We show that the vacuum stability condition and the experimental bound on μ→e γ together put a constrain on heavy neutrino mass MR>3.3 TeV. Finally we show that the observation of SSDs associated with jets at the LHC needs much larger luminosity than available at present. We have estimated the possible maximum cross-section for this process at the LHC and show that with an integrated luminosity 100 fb-1 it may be possible to observe the SSD signals as long as MR < 400 GeV.

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13

XING, ZHI-ZHONG. « FLAVOR MIXING AND CP VIOLATION OF MASSIVE NEUTRINOS ». International Journal of Modern Physics A 19, n^o 01 (10 janvier 2004) : 1–79. http://dx.doi.org/10.1142/s0217751x04016969.

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We present an overview of recent progress in the phenomenological study of neutrino masses, lepton flavor mixing and CP violation. We concentrate on the model-independent properties of massive neutrinos, both in vacuum and in matter. Current experimental constraints on the neutrino mass spectrum and the lepton flavor mixing parameters are summarized. The Dirac- and Majorana-like phases of CP violation, which are associated respectively with the long-baseline neutrino oscillations and the neutrinoless double beta decay, are discussed in detail. The seesaw mechanism, the leptogenesis scenario and the strategies to construct lepton mass matrices are briefly described. The features of flavor mixing between one sterile neutrino and three active neutrinos are also explored.

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14

Merle, Alexander, et Werner Rodejohann. « Getting Information on|Ue3|2from Neutrinoless Double Beta Decay ». Advances in High Energy Physics 2007 (2007) : 1–15. http://dx.doi.org/10.1155/2007/82674.

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We consider the possibility to gain information on the lepton mixing matrix element|Ue3|from an improved experimental limit on the effective neutrino mass governing neutrinoless double beta decay. We show that typically a lower limit on|Ue3|as a function of the smallest neutrino mass can be set. Furthermore, we give the values of the sum of neutrino masses and|Ue3|which are allowed and forbidden by an experimental upper limit on the effective mass. Alternative explanations for neutrinoless double beta decay, Dirac neutrinos or unexplained cosmological features would be required if future measurements showed that the values lie in the respective regions. Moreover, we show that a measurement of|Ue3|from neutrinoless double beta decay is very difficult due to the expected errors on the effective mass and the oscillation parameters.

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15

WANG, YIFANG. « RECENT RESULTS OF NON-ACCELERATOR-BASED NEUTRINO EXPERIMENTS ». International Journal of Modern Physics A 20, n^o 22 (10 septembre 2005) : 5244–53. http://dx.doi.org/10.1142/s0217751x05028752.

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Recent results of non-accelerator-based experiments, including those of solar, atmospheric, and reactor neutrinos oscillations, neutrinoless double-beta decays, and neutrino magnetic moments, are reviewed. Future projects and their respective prospects are summarized.

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16

Liu, Jun-Hao, et Shun Zhou. « Another look at the impact of an eV-mass sterile neutrino on the effective neutrino mass of neutrinoless double-beta decays ». International Journal of Modern Physics A 33, n^o 02 (20 janvier 2018) : 1850014. http://dx.doi.org/10.1142/s0217751x18500148.

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The possible existence of an eV-mass sterile neutrino, slightly mixing with ordinary active neutrinos, is not yet excluded by neutrino oscillation experiments. Assuming neutrinos to be Majorana particles, we explore the impact of such a sterile neutrino on the effective neutrino mass of neutrinoless double-beta decays [Formula: see text], where [Formula: see text] and [Formula: see text] (for [Formula: see text]) denote respectively the absolute masses and the first-row elements of the [Formula: see text] neutrino flavor mixing matrix [Formula: see text], for which a full parametrization involves three Majorana-type CP-violating phases [Formula: see text]. A zero effective neutrino mass [Formula: see text] is possible, no matter whether three active neutrinos take the normal or inverted mass ordering, and its implications for the parameter space are examined in great detail. In particular, given the best-fit values of [Formula: see text] and [Formula: see text] from the latest global analysis of neutrino oscillation data, a three-dimensional view of [Formula: see text] in the [Formula: see text]-plane is presented and further compared with that of the counterpart [Formula: see text] in the absence of any sterile neutrino.

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17

Klapdor-Kleingrothaus, H. V., et U. Sarkar. « Consequences of Neutrinoless Double Beta Decay and WMAP ». Modern Physics Letters A 18, n^o 32 (20 octobre 2003) : 2243–54. http://dx.doi.org/10.1142/s0217732303011988.

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Observation of the neutrinoless double beta decay (0νββ) has established that there is lepton number violation in nature and the neutrino masses are Majorana in nature. It also gives the absolute mass of the neutrinos and discriminates between different models of neutrino masses. The allowed amount of lepton number violation puts severe constraints on some possible new physics beyond the standard model. The recent results from WMAP are consistent with the consequences of the neutrinoless double beta decay. They improve some of these constraints very marginally, which we shall summarize here. We mention the new physics which is not affected by WMAP, and which could make the limits from the neutrinoless double beta decay even consistent with much tighter future cosmological limits.

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Grange, Joseph, et Teppei Katori. « Charged current quasi-elastic cross-section measurements in MiniBooNE ». Modern Physics Letters A 29, n^o 12 (20 avril 2014) : 1430011. http://dx.doi.org/10.1142/s0217732314300110.

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The neutrino-induced charged-current quasi-elastic (CCQE, νl + n → l- + p or [Formula: see text]) interaction is the most abundant interaction around 1 GeV, and it is the most fundamental channel to study neutrino oscillations. Recently, MiniBooNE published both muon neutrino1 and muon anti-neutrino2 double differential cross-sections on carbon. In this review, we describe the details of these analyses and include some historical remarks.

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CREMONESI, OLIVIERO. « NEUTRINOLESS DOUBLE BETA DECAY ». International Journal of Modern Physics : Conference Series 12 (janvier 2012) : 80–89. http://dx.doi.org/10.1142/s2010194512006289.

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Neutrinoless double beta decay (ββ(0ν)) is presently the only practical tool for probing the character of neutrinos. In case neutrinos are Majorana particles ββ(0ν) can provide also fundamental informations on their absolute mass scale. The present status of experiments searching for ββ(0ν) is reviewed and the most relevant results discussed. A possibility to observe ββ(0ν) at a neutrino mass scale in the range 10-50 meV looks possible according to our present knowledge of the neutrino masses and mixing parameters. A review of the future projects and of the most relevant parameters contributing to the experimental sensitivity iss finally outlined.

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Berger, Micheal S., et Maria Dawid. « A Froggatt–Nielsen flavor model for neutrino physics ». International Journal of Modern Physics A 34, n^o 19 (10 juillet 2019) : 1950102. http://dx.doi.org/10.1142/s0217751x19501021.

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Superheavy neutrinos can, via the seesaw model, provide a mechanism for lepton number violation. If they are combined with flavor violation as characterized by the Froggatt–Nielsen mechanism, then the phenomenology for the neutrinos in oscillation experiments, neutrinoless double beta decay, and other experiments can be described by a relatively few number of parameters. We describe the low-energy neutrino mass matrix and show that the results are consistent with currently available data.

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Lesgourgues, Julien, et Sergio Pastor. « Neutrino Mass from Cosmology ». Advances in High Energy Physics 2012 (2012) : 1–34. http://dx.doi.org/10.1155/2012/608515.

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Neutrinos can play an important role in the evolution of the universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos, and we describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to beta decay and neutrinoless double-beta decay experiments. We show how the analysis of current cosmological observations, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure, provides an upper bound on the sum of neutrino masses of order 1 eV or less, with very good perspectives from future cosmological measurements which are expected to be sensitive to neutrino masses well into the sub-eV range.

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HE, XIAO-GANG, et A. ZEE. « GEOMETRIC MEAN NEUTRINO MASS RELATION ». Modern Physics Letters A 22, n^o 25n28 (14 septembre 2007) : 2107–12. http://dx.doi.org/10.1142/s0217732307025352.

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Present experimental data from neutrino oscillations have provided much information about the neutrino mixing angles. Since neutrino oscillations only determine the mass squared differences [Formula: see text], the absolute values for neutrino masses mi, can not be determined using data just from oscillations. In this work we study implications on neutrino masses from a geometric mean mass relation [Formula: see text] which enables one to determined the absolute masses of the neutrinos. We find that the central values of the three neutrino masses and their 2σ errors to be m1 = (1.58 ± 0.18) meV , m2 = (9.04 ± 0.42) meV , and m3 = (51.8 ± 3.5) meV . Implications for cosmological observation, beta decay and neutrinoless double beta decays are discussed.

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BARGER, V., D. MARFATIA et K. WHISNANT. « PROGRESS IN THE PHYSICS OF MASSIVE NEUTRINOS ». International Journal of Modern Physics E 12, n^o 05 (octobre 2003) : 569–647. http://dx.doi.org/10.1142/s0218301303001430.

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The current status of the physics of massive neutrinos is reviewed with a forward-looking emphasis. The article begins with the general phenomenology of neutrino oscillations in vacuum and matter and documents the experimental evidence for oscillations of solar, reactor, atmospheric and accelerator neutrinos. Both active and sterile oscillation possibilities are considered. The impact of cosmology (BBN, CMB, leptogenesis) and astrophysics (supernovae, highest energy cosmic rays) on neutrino observables and vice versa, is evaluated. The predictions of grand unified, radiative and other models of neutrino mass are discussed. Ways of determining the unknown parameters of three-neutrino oscillations are assessed, taking into account eight-fold degeneracies in parameters that yield the same oscillation probabilities, as well as ways to determine the absolute neutrino mass scale (from beta-decay, neutrinoless double-beta decay, large scale structure and Z-bursts). Critical unknowns at present are the amplitude of νμ→νe oscillations and the hierarchy of the neutrino mass spectrum; the detection of CP violation in the neutrino sector depends on these and on an unknown phase. The estimated neutrino parameter sensitivities at future facilities (reactors, superbeams, neutrino factories) are given. The overall agenda of a future neutrino physics program to construct a bottom-up understanding of the lepton sector is presented.

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Valle, José W. F. « Status and implications of neutrino masses : A brief panorama ». International Journal of Modern Physics A 30, n^o 13 (4 mai 2015) : 1530034. http://dx.doi.org/10.1142/s0217751x15300343.

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With the historic discovery of the Higgs boson our picture of particle physics would have been complete were it not for the neutrino sector and cosmology. I briefly discuss the role of neutrino masses and mixing upon gauge coupling unification, electroweak breaking and the flavor sector. Time is ripe for new discoveries such as leptonic CP violation, charged lepton flavor violation and neutrinoless double beta decay. Neutrinos could also play a role in elucidating the nature of dark matter and cosmic inflation.

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Vivekanand, P. Verma et K. Chaturvedi. « Limits on Effective Masses of Light and Heavy Majorana Neutrinos for Positron Emitting Modes of Double Beta Decay ». Journal of Scientific Research 14, n^o 1 (1 janvier 2022) : 1–10. http://dx.doi.org/10.3329/jsr.v14i1.50390.

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Double beta decay is a rare weak interaction process in which two identical nucleons inside the nucleus decay with or without the emission of neutrinos. If the neutrinoless double beta decay is observed, the (e+DBD) processes will play a crucial role in discriminating the finer issues like the dominance of Majorana neutrino mass or the right-handed current. In the present work, we have obtained the limits on the effective mass of light and heavy Majorana neutrinos for the electron-positron conversion and double positron-emitting modes of 96Ru, 106Cd, 124Xe, and 130Ba isotopes, using the nuclear transition matrix elements NTMEs M(0ν) and M(0N) for light and heavy Majorana neutrinos obtained in projected Hartree-Fock Bogoliubov (PHFB) model. The predicted half-lives and corresponding extracted limits on heavy neutrino mass <MN> is discussed. We have also calculated nuclear sensitivities ξ(0ν) and ξ(0N) due to the light and heavy neutrino exchange, respectively. Finally, the mass limits are obtained using various phase space factors (PSF), and the effect of this PSF on mass limits is discussed.

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PATGIRI, MAHADEV, et N. NIMAI SINGH. « RIGHT-HANDED MAJORANA NEUTRINO MASS MATRICES FOR GENERATING BIMAXIMAL MIXINGS IN DEGENERATE AND INVERTED MODELS OF NEUTRINOS ». International Journal of Modern Physics A 18, n^o 05 (20 février 2003) : 743–53. http://dx.doi.org/10.1142/s0217751x03014022.

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An attempt is made to generate the bimaximal mixings of the three species of neutrinos from the textures of the right-handed Majorana neutrino mass matrices. We extend our earlier work in this paper for the generation of the nearly degenerate as well as the inverted hierarchical models of the left-handed Majorana neutrino mass matrices using the non-diagonal textures of the right-handed Majorana neutrino mass matrices and the diagonal form of Dirac neutrino mass matrices, within the framework of the see-saw mechanism in a model independent way. Such Majorana neutrino mass models are important in explaining the recently reported result on the neutrinoless double beta decay (0νββ) experiment, together with the earlier established data on LMA MSW solar and atmospheric neutrino oscillations.

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Chianese, Marco, Damiano F. G. Fiorillo, Gennaro Miele et Stefano Morisi. « Investigating two heavy neutral leptons neutrino seesaw mechanism at SHiP ». International Journal of Modern Physics A 34, n^o 08 (20 mars 2019) : 1950047. http://dx.doi.org/10.1142/s0217751x19500477.

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One of the main purposes of SHiP experiment is to shed light on neutrino mass generation mechanisms like the so-called seesaw. We consider a minimal type-I seesaw neutrino mass mechanism model with two heavy neutral leptons (right-handed or sterile neutrinos) with arbitrary masses. Extremely high active-sterile mixing angle requires a correlation between the phases of the Dirac neutrino couplings. Actual experimental limits on the half-life of neutrinoless double beta decay [Formula: see text]-rate on the active-sterile mixing angle are not significative in constraining the masses or the mixing measurable by SHiP.

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HEUSCH, CLEMENS A., et PETER MINKOWSKI. « A STRATEGY FOR DISCOVERING HEAVY NEUTRINOS ». International Journal of Modern Physics A 11, n^o 09 (10 avril 1996) : 1607–11. http://dx.doi.org/10.1142/s0217751x96000791.

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Same-sign lepton collisions in the TeV energy range may well have the unique capability to search for clear signals for the exchange of heavy Majorana neutrinos. Lepton-flavor-violating transitions e−e−→W−W− can thus contribute to the understanding of two unsolved riddles in particle physics: the neutrino mass problem and the question of the Dirac or Majorana character of heavy neutrinos. This search is not similarly accessible to such effects as neutrinoless double beta decay. The resulting experimental signatures are hard to miss.

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SENJANOVIĆ, GORAN. « SEESAW AT LHC THROUGH LEFT–RIGHT SYMMETRY ». International Journal of Modern Physics A 26, n^o 09 (10 avril 2011) : 1469–91. http://dx.doi.org/10.1142/s0217751x1105302x.

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I argue that LHC may shed light on the nature of neutrino mass through the probe of the seesaw mechanism. The smoking gun signature is lepton number violation through the production of same sign lepton pairs, a collider analogy of the neutrinoless double beta decay. I discuss this in the context of left–right symmetric theories, which led originally to neutrino mass and the seesaw mechanism. A WR gauge boson with a mass in a few TeV region could easily dominate neutrinoless double beta decay, and its discovery at LHC would have spectacular signatures of parity restoration and lepton number violation. Moreover, LHC can measure the masses of the right-handed neutrinos and the right-handed leptonic mixing matrix, which could in turn be used to predict the rates for neutrinoless double decay and lepton flavor violating violating processes. The LR scale at the LHC energies offers great hope of observing these low energy processes in the present and upcoming experiments.

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Nieuwenhuizen, Theodorus Maria. « The Standard Model of Particle Physics with Diracian Neutrino Sector ». Symmetry 11, n^o 8 (3 août 2019) : 994. http://dx.doi.org/10.3390/sym11080994.

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The minimally extended standard model of particle physics contains three right handed or sterile neutrinos, coupled to the active ones by a Dirac mass matrix and mutually by a Majorana mass matrix. In the pseudo-Dirac case, the Majorana terms are small and maximal mixing of active and sterile states occurs, which is generally excluded for solar neutrinos. In a “Diracian” limit, the physical masses become pairwise degenerate and the neutrinos attain a Dirac signature. Members of a pair do not oscillate mutually so that their mixing can be undone, and the standard neutrino model follows as a limit. While two Majorana phases become physical Dirac phases and three extra mass parameters occur, a better description of data is offered. Oscillation problems are worked out in vacuum and in matter. With lepton number –1 assigned to the sterile neutrinos, the model still violates lepton number conservation and allows very feeble neutrinoless double beta decay. It supports a sterile neutrino interpretation of Earth-traversing ultra high energy events detected by ANITA.

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GÓŹDŹ, MAREK, et WIESŁAW A. KAMIŃSKI. « SUPPRESSION OF 0ν2β DECAY FROM CP VIOLATION ». International Journal of Modern Physics E 16, n^o 02 (février 2007) : 561–65. http://dx.doi.org/10.1142/s0218301307005995.

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The observed phenomenon of neutrino oscillations is interpreted as the proof that neutrinos must have mass. As this is true for the neutrinos in the mass basis, the mass matrix in the flavor (weak) basis may still contain zeros. This can happen if the CP violating phases, usually neglected, come into play and result in suppression of processes which half-life depends on the masses of νe, νμ, or ντ. In the present paper we investigate the possibility of such suppression of the neutrinoless double beta decay (0ν2β).

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Hernandez-Molinero, Beatriz, Raul Jimenez et Carlos Peña Garay. « Distinguishing Dirac vs. Majorana neutrinos : a cosmological probe ». Journal of Cosmology and Astroparticle Physics 2022, n^o 08 (1 août 2022) : 038. http://dx.doi.org/10.1088/1475-7516/2022/08/038.

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Abstract Cosmic background neutrinos (CνB) helicity composition is different for Dirac or Majorana neutrinos making detectors based on CνB capture sensitive to the nature of neutrinos. We calculate, for the first time, the helicity changes of neutrinos crossing dark matter fields, to quantitatively calculate this effect on the capture rate. We show that a fraction of neutrinos change their helicity, regardless of them being deflected by a void or a dark matter halo. The average signal from the 100 most massive voids or halos in a Gpc3 gives a prediction that if neutrinos are Dirac, the density of the CνB background measured on Earth should be 48 cm-3 for left-helical neutrinos, a decrease of 15% (53.6 cm-3; 5%) for a halo (void) with respect to the standard calculation without including gravitational effects due to large scale structures. In terms of the total capture rate in a 100 g tritium detector, this translates in 4.9+1.1 -0.8 neutrinos per year for the Dirac case, as a function of the unknown neutrino mass scale, or 8.1 per year if neutrinos are Majorana. Thus although smaller than the factor two for the non-relativistic case, it is still large enough to be detected and it highlights the power of future CνB detectors, as an alternative to neutrinoless double beta decay experiments, to discover the neutrino nature.

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AKASLAN, S., et A. U. YILMAZER. « EFFECTS OF CP VIOLATING PHASES ON THE INVERSE NEUTRINOLESS DOUBLE BETA SCATTERING e-e- → W-W- ». Modern Physics Letters A 27, n^o 14 (5 mai 2012) : 1250053. http://dx.doi.org/10.1142/s0217732312500538.

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The most important open problems of the today's neutrino physics are the absolute values of the neutrino masses, the determination of the Dirac or the Majorana character and better measurements of the mixing matrix elements. Results of the neutrino oscillations experiments strongly confirm that the neutrinos have nonzero masses. Experiments give information about the differences between the squares of the masses but not any knowledge on their absolute values. Similarly neutrino oscillation phenomena does not help us to understand their Dirac or Majorana character. One of the processes that could clarify this important point is the double beta decay and the search is still going on but not yielded any positive results due to the big experimental difficulties. Also the inverse of this decay, e-e- → W-W- is another process that could be tested at the accelerators. This process is possible only if the neutrinos have masses and they are Majorana particles. Since neutrinos could have very tiny masses and the cross section of the above process is proportional to the square of the effective neutrino mass it is an extremely rare process. Also it violates total lepton number by two units, Δ = 2. In the literature the inverse neutrinoless double beta scattering have been extensively studied, in this article we obtain the relevant helicity amplitudes, investigate the effects of the neutrino mixing matrix elements, especially the roles of the CP violating phases and the possible CP asymmetries.

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Das, Pritam, et Mrinal Kumar Das. « Phenomenology of keV sterile neutrino in minimal extended seesaw ». International Journal of Modern Physics A 35, n^o 22 (7 août 2020) : 2050125. http://dx.doi.org/10.1142/s0217751x20501250.

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We explore the possibility of a single generation of keV scale sterile neutrino [Formula: see text] as a dark matter candidate within the minimal extended seesaw (MES) framework and its influence in neutrinoless double beta decay [Formula: see text] study. Three hierarchical right-handed neutrinos were considered to explain neutrino mass. We also address baryogenesis via the mechanism of thermal leptogenesis considering the decay of the lightest RH neutrino to a lepton and Higgs doublet. A generic model based on [Formula: see text] flavor symmetry is constructed to explain both normal and inverted hierarchy mass pattern of neutrinos. Significant results on effective neutrino masses are observed in presence of sterile mass [Formula: see text] and active-sterile mixing [Formula: see text] in [Formula: see text]. Results from [Formula: see text] give stringent upper bounds on the active-sterile mixing matrix element. To establish sterile neutrino as dark matter within this model, we checked decay width and relic abundance of the sterile neutrino, which restricted sterile mass [Formula: see text] within some definite bounds. Constrained regions on the CP phases and Yukawa couplings are obtained from [Formula: see text] and baryogenesis results. Co-relations among these observable are also established and discussed within this framework.

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Yu, C. H., S. I. Alvis, I. J. Arnquist, F. T. Avignone, A. S. Barabash, C. J. Barton, F. E. Bertrand et al. « The Majorana Demonstrator Status and Preliminary Results ». EPJ Web of Conferences 178 (2018) : 01006. http://dx.doi.org/10.1051/epjconf/201817801006.

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The Majorana Collaboration is using an array of high-purity Ge detectors to search for neutrinoless double-beta decay in 76Ge. Searches for neutrinoless double-beta decay are understood to be the only viable experimental method for testing the Majorana nature of the neutrino. Observation of this decay would imply violation of lepton number, that neutrinos are Majorana in nature, and provide information on the neutrino mass. The Majorana Demonstrator comprises 44.1 kg of p-type point-contact Ge detectors (29.7 kg enriched in 76Ge) surrounded by a low-background shield system. The experiment achieved a high efficiency of converting raw Ge material to detectors and an unprecedented detector energy resolution of 2.5 keV FWHM at Qββ. The Majorana collaboration began taking physics data in 2016. This paper summarizes key construction aspects of the Demonstrator and shows preliminary results from initial data.

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KLAPDOR-KLEINGROTHAUS, H. V., et U. SARKAR. « IMPLICATIONS OF OBSERVED NEUTRINOLESS DOUBLE BETA DECAY ». Modern Physics Letters A 16, n^o 38 (14 décembre 2001) : 2469–82. http://dx.doi.org/10.1142/s0217732301005850.

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Recently a positive indication of the neutrinoless double beta decay has been announced. We study the implications of this result taking into consideration earlier results on atmospheric neutrinos and solar neutrinos. We also include in our discussions the recent results from SNO and K2K. We point out that on the confidence level given for the double beta signal, the neutrino mass matrices are now highly constrained. All models predicting Dirac masses are ruled out and leptogenesis becomes a natural choice. Only the degenerate and the inverted hierarchical solutions are allowed for the three-generation Majorana neutrinos. In both cases we find that the radiative corrections destabilize the solutions and the LOW, VO and Just So solutions of the solar neutrinos are ruled out. For the four-generation case only the inverted hierarchical scenario is allowed.

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NISHIURA, HIROYUKI, KOUICHI MATSUDA et TAKESHI FUKUYAMA. « CONSTRAINTS OF MIXING ANGLES FROM LEPTON NUMBER VIOLATING PROCESSES ». Modern Physics Letters A 14, n^o 06 (28 février 1999) : 433–45. http://dx.doi.org/10.1142/s0217732399000493.

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We discuss the constraints of lepton mixing angles from lepton number violating processes such as neutrinoless double beta decay, μ--e+ conversion and K decay, K-→π+μ-μ- which are allowed only if neutrinos are Majorana particles. The rates of these processes are proportional to the averaged neutrino mass defined by [Formula: see text] in the absence of right-handed weak coupling. Here a, b(j) are flavor(mass) eigenstates and Uaj is the left-handed lepton mixing matrix. We give general conditions imposed on <mν>ab in terms of mi, lepton mixing angles and CP violating phases (three phases in Majorana neutrinos). These conditions are reduced to the constraints among mi, lepton mixing angles and <mν>ab which are irrelevant to the concrete values of CP phases. Given a <mν>ab experimentally, these conditions constrain mi and the lepton mixing angles. Though these constraints are still loose except for neutrinoless double beta decay, they will become helpful through rapid improvements of experiments. By using these constraints we also derive the limits on averaged neutrino masses for μ--e+ conversion and K decay, K-→π+μ-μ-, respectively. We also present the bounds for CP phases in terms of mi, mixing angles and <mν>ab.

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Caravaca, J. « SNO+ status and prospects ». International Journal of Modern Physics A 35, n^o 34n35 (18 décembre 2020) : 2044013. http://dx.doi.org/10.1142/s0217751x20440133.

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SNO+ is a multi-purpose experiment whose main goal is to study the nature of the neutrino mass through the observation of neutrinoless double-beta decay. Detection of this rare process would indicate that neutrinos are elementary Majorana particles, proving that lepton number is not conserved. The SNO+ detector will operate in three distinct phases with different target materials: water, pure liquid scintillator and tellurium-loaded liquid scintillator. During the water phase, the external backgrounds were confirmed to be within expectation, new limits on specific channels of invisible nucleon decay modes were set and the Boron-8 solar neutrino flux was measured and confirmed to be compatible with previous measurements. With a completed water phase, SNO+ is moving towards its main Tellurium-loaded phase. Here, we report the status of the experiment, the recent results and the potential of SNO+ for neutrinoless double-beta decay search.

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OBARA, MIDORI, et ZHI-ZHONG XING. « GENERALIZED FUKUGITA–TANIMOTO–YANAGIDA NEUTRINO MASS ANSATZ ». International Journal of Modern Physics E 16, n^o 05 (juin 2007) : 1405–16. http://dx.doi.org/10.1142/s0218301307006769.

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We generalize the Fukugita–Tanimoto–Yanagida ansatz by allowing the masses of three heavy right-handed Majorana neutrinos, Mi (i = 1,2,3), to be partially non-degenerate and search for the parameter space which can be consistent with the current neutrino oscillation data, for three non-degenerate mass cases (A) M3 = M2 ≠ M1, (B) M2 = M1 ≠ M3 and (C) M1 = M3 ≠ M2. We also examine the effect of the deviation from the complete mass degeneracy in each case. Finally, we obtain the numerical constraints on three light neutrino masses, three neutrino mixing angles and three CP-violating phases, together with the predictions for the Jarlskog invariant of CP violation and the effective masses of the tritium beta decay and the neutrinoless double-beta decay.

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KEUM, YONG-YEON. « NEUTRINO MASS BOUNDS ». International Journal of Modern Physics : Conference Series 01 (janvier 2011) : 140–50. http://dx.doi.org/10.1142/s2010194511000195.

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We investigate the way how the total mass sum of neutrinos can be constrained from the neutrinoless double beta decay and cosmological probes with cosmic microwave background (WMAP 3-year results), large scale structures including 2dFGRS and SDSS data sets. First we discuss, in brief, on the current status of neutrino mass bounds from neutrino beta decays and cosmic constrain within the flat ΛCMD model. In addition, we explore the interacting neutrino dark-energy model, where the evolution of neutrino masses is determined by quintessence scalar filed, which is responsable for cosmic acceleration today. Assuming the flatness of the universe, the constraint we can derive from the current observation is ∑ mν < 0.87 eV at the 95 % confidence level, which is consistent with ∑ mν < 0.68 eV in the flat ΛCDM model. Finally we discuss the future prospect of the neutrino mass bound with weak-lensing effects.

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Vien, Vo Van, et Hoang Ngoc Long. « Neutrino mixing with nonzero θ13 and CP violation in the 3-3-1 model based on A4 flavor symmetry ». International Journal of Modern Physics A 30, n^o 21 (22 juillet 2015) : 1550117. http://dx.doi.org/10.1142/s0217751x15501171.

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We propose a 3-3-1 model with neutral fermions based on [Formula: see text] flavor symmetry responsible for fermion masses and mixings with nonzero [Formula: see text]. To get realistic neutrino mixing, we just add a new [Formula: see text] triplet being in [Formula: see text] under [Formula: see text]. The neutrinos get small masses from two [Formula: see text] antisextets and one [Formula: see text] triplet. The model can fit the present data on neutrino masses and mixing as well as the effective mass governing neutrinoless double beta decay. Our results show that the neutrino masses are naturally small and a little deviation from the tri-bimaximal neutrino mixing form can be realized. The Dirac CP violation phase [Formula: see text] is predicted to either [Formula: see text] or [Formula: see text] with [Formula: see text].

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Horoi, Mihai. « Double Beta Decay : A Shell Model Approach ». Physics 4, n^o 4 (26 septembre 2022) : 1135–49. http://dx.doi.org/10.3390/physics4040074.

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Studies of weak interaction in nuclei are important tools for testing different aspects of the fundamental symmetries of the Standard Model. Neutrinoless double beta decay offers an unique venue of investigating the possibility that neutrinos are Majorana fermions and that the lepton number conservation law is violated. Here, I use a shell model approach to calculate the nuclear matrix elements needed to extract the lepton-number-violating parameters of a few nuclei of experimental interest from the latest experimental lower limits of neutrinoless double beta decay half-lives. The analysis presented here could reveal valuable information regarding the dominant neutrinoless double beta decay mechanism if experimental half-life data become available for different isotopes. A complementary shell model analysis of the two-neutrino double beta decay nuclear matrix elements and half-lives is also presented.

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Andringa, S., E. Arushanova, S. Asahi, M. Askins, D. J. Auty, A. R. Back, Z. Barnard et al. « Current Status and Future Prospects of the SNO+ Experiment ». Advances in High Energy Physics 2016 (2016) : 1–21. http://dx.doi.org/10.1155/2016/6194250.

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SNO+ is a large liquid scintillator-based experiment located 2 km underground at SNOLAB, Sudbury, Canada. It reuses the Sudbury Neutrino Observatory detector, consisting of a 12 m diameter acrylic vessel which will be filled with about 780 tonnes of ultra-pure liquid scintillator. Designed as a multipurpose neutrino experiment, the primary goal of SNO+ is a search for the neutrinoless double-beta decay (0νββ) of130Te. In Phase I, the detector will be loaded with 0.3% natural tellurium, corresponding to nearly 800 kg of130Te, with an expected effective Majorana neutrino mass sensitivity in the region of 55–133 meV, just above the inverted mass hierarchy. Recently, the possibility of deploying up to ten times more natural tellurium has been investigated, which would enable SNO+ to achieve sensitivity deep into the parameter space for the inverted neutrino mass hierarchy in the future. Additionally, SNO+ aims to measure reactor antineutrino oscillations, low energy solar neutrinos, and geoneutrinos, to be sensitive to supernova neutrinos, and to search for exotic physics. A first phase with the detector filled with water will begin soon, with the scintillator phase expected to start after a few months of water data taking. The0νββPhase I is foreseen for 2017.

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KLAPDOR-KLEINGROTHAUS, H. V. « TO BE OR NOT TO BE ? — FIRST EVIDENCE FOR NEUTRINOLESS DOUBLE-BETA DECAY ». International Journal of Modern Physics A 18, n^o 22 (10 septembre 2003) : 4113–28. http://dx.doi.org/10.1142/s0217751x03017403.

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Double beta decay is indispensable to solve the question of the neutrino mass matrix together with ν oscillation experiments. Recent analysis of the most sensitive experiment since nine years - the HEIDELBERG-MOSCOW experiment in Gran-Sasso - yields a first indication for the neutrinoless decay mode. This result is the first evidence for lepton number violation and proves the neutrino to be a Majorana particle. We give the present status of the analysis in this report. It excludes several of the neutrino mass scenarios allowed from present neutrino oscillation experiments - only degenerate scenarios and those with inverse mass hierarchy survive. This result allows neutrinos to still play an important role as dark matter in the Universe. To improve the accuracy of the present result, considerably enlarged experiments are required, such as GENIUS. A GENIUS Test Facility has been funded and will come into operation by early 2003.

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Vien, V. V. « Neutrino mass and mixing in the 3-3-1 model with neutral leptons based on D4flavor symmetry ». Modern Physics Letters A 29, n^o 23 (24 juillet 2014) : 1450122. http://dx.doi.org/10.1142/s0217732314501223.

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We propose a new D4flavor model based on SU (3)C⊗ SU (3)L⊗ U (1)Xgauge symmetry responsible for fermion masses and mixings in which all fermion fields act only as singlets under D4which differs from our previous work. The neutrinos get small masses from two SU (3)Lanti-sextets and one SU (3)Ltriplet which are all in singlets under D4. If a SU (3)LHiggs triplet, lying in [Formula: see text] under D4, is considered as a perturbation the corresponding neutrino mass mixing matrix gets the most general form. In this case, the model can fit the most recent data on neutrino masses and mixing with nonzero θ13. Our results show that the neutrino masses are naturally small. The sum of three light neutrino masses and the effective mass governing neutrinoless double beta decay are obtained that are consistent with the recent data.

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KLAPDOR-KLEINGROTHAUS, H. V. « FROM NUCLEAR PHYSICS TO PHYSICS BEYOND THE STANDARD MODEL : FIRST EVIDENCE FOR LEPTON NUMBER VIOLATION AND THE MAJORANA CHARACTER OF NEUTRINOS ». International Journal of Modern Physics D 13, n^o 10 (décembre 2004) : 2107–26. http://dx.doi.org/10.1142/s0218271804006656.

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Nuclear double beta decay provides an extraordinarily broad potential to search for beyond-standard-model physics. The occurrence of the neutrinoless decay(0νββ) mode has fundamental consequences: first, the total lepton number is not conserved, and second, the neutrino is a Majorana particle. Furthermore, the measured effective mass provides an absolute scale of the neutrino mass spectrum. In addition, double beta experiments yield sharp restrictions for other beyond-standard-model physics. These include SUSY models (R-parity breaking and conserving), leptoquarks (leptoquark-Higgs coupling), compositeness, left-right symmetric models (right-handed W boson mass), test of special relativity and of the equivalence principle in the neutrino sector and others. First evidence for neutrinoless double beta decay was reported by the HEIDELBERG–MOSCOW experiment in 2001. The HEIDELBERG–MOSCOW experiment is by far the most sensitive0νββ experiment since more than 10 years. It is operating 11 kg of enriched 76Ge in the GRAN SASSO Underground Laboratory. The analysis of the data taken from 2 August 1990–20 May 2003 is presented here. The collected statistics is 71.7 kg y. The background achieved in the energy region of the Q value for double beta decay is 0.11 events/kg y keV. The two-neutrino accompanied half-life is determined on the basis of more than 100,000 events to be [Formula: see text] years. The confidence level for the neutrinoless signal has been improved to a 4.2σ level. The half-life is [Formula: see text] years. The effective neutrino mass deduced is (0.2–0.6) eV (99.73% C.L.), with the consequence that neutrinos have degenerate masses. The sharp boundaries for other beyond SM physics, mentioned above, are comfortably competitive to the corresponding results from high-energy accelerators like TEVATRON, HERA, etc.

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FUKUYAMA, TAKESHI, KOUICHI MATSUDA et HIROYUKI NISHIURA. « CONSTRAINTS OF MIXING ANGLES FROM NEUTRINO OSCILLATION EXPERIMENTS AND NEUTRINOLESS DOUBLE BETA DECAY ». Modern Physics Letters A 13, n^o 28 (14 septembre 1998) : 2279–87. http://dx.doi.org/10.1142/s0217732398002424.

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From the analyses of the recent data of neutrino oscillation experiments (especially the CHOOZ and the super-Kamiokande experiments), we discuss how these data affect the neutrinoless double beta decay ((ββ)0ν) rate and vice versa assuming that neutrinos are Majorana particles. For the case of m1~m2≪m3 (mi are neutrino masses), we obtain, from the data of the CHOOZ and super-Kamiokande, 0.28 ≲ sin 2θ23≲ 0.76 and sin 2θ13≲ 0.05. Combining the latter constraint with the analysis of the "averaged" neutrino mass <mν> appeared in (ββ)0ν, we find that [Formula: see text], which leads to the constraint on <mν> as <mν> ≲ 0.05m3 + (1 - 0.05)m2. For the case of m1≪m2~ m3, we find that the data of neutrino oscillation experiments and (ββ)0ν imply the following constraints of mixing angles: if 0.95m3≲ <mν> < m3, [Formula: see text]. If <mν> ≲ 0.95m3, [Formula: see text] and [Formula: see text].

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Agostini, M., A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti et al. « Probing Majorana neutrinos with double-β decay ». Science 365, n^o 6460 (5 septembre 2019) : 1445–48. http://dx.doi.org/10.1126/science.aav8613.

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A discovery that neutrinos are Majorana fermions would have profound implications for particle physics and cosmology. The Majorana character of neutrinos would make possible the neutrinoless double-β (0νββ) decay, a matter-creating process without the balancing emission of antimatter. The GERDA Collaboration searches for the 0νββ decay of 76Ge by operating bare germanium detectors in an active liquid argon shield. With a total exposure of 82.4 kg⋅year, we observe no signal and derive a lower half-life limit of T1/2 > 0.9 × 1026 years (90% C.L.). Our T1/2 sensitivity, assuming no signal, is 1.1 × 1026 years. Combining the latter with those from other 0νββ decay searches yields a sensitivity to the effective Majorana neutrino mass of 0.07 to 0.16 electron volts.

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GUO, WAN-LEI, ZHI-ZHONG XING et SHUN ZHOU. « NEUTRINO MASSES, LEPTON FLAVOR MIXING AND LEPTOGENESIS IN THE MINIMAL SEESAW MODEL ». International Journal of Modern Physics E 16, n^o 01 (janvier 2007) : 1–50. http://dx.doi.org/10.1142/s0218301307004898.

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We present a review of neutrino phenomenology in the minimal seesaw model (MSM), an economical and intriguing extension of the Standard Model with only two heavy right-handed Majorana neutrinos. Given current neutrino oscillation data, the MSM can predict the neutrino mass spectrum and constrain the effective masses of the tritium beta decay and the neutrinoless double-beta decay. We outline five distinct schemes to parameterize the neutrino Yukawa-coupling matrix of the MSM. The lepton flavor mixing and baryogenesis via leptogenesis are investigated in some detail by taking account of possible texture zeros of the Dirac neutrino mass matrix. We derive an upper bound on the CP-violating asymmetry in the decay of the lighter right-handed Majorana neutrino. The effects of the renormalization-group evolution on the neutrino mixing parameters are analyzed, and the correlation between the CP-violating phenomena at low and high energies is highlighted. We show that the observed matter-antimatter asymmetry of the Universe can naturally be interpreted through the resonant leptogenesis mechanism at the TeV scale. The lepton-flavor-violating rare decays, such as μ→e+γ, are also discussed in the supersymmetric extension of the MSM.

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Šimkovic, Fedor, Rastislav Dvornický et Dušan Štefánik. « Two neutrino double-beta decay and effective axial-vector coupling constant ». EPJ Web of Conferences 194 (2018) : 02002. http://dx.doi.org/10.1051/epjconf/201819402002.

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The theoretical and experimental study of the two-neutrino double-beta decay (2νββ-decay) is of crucial importance for reliable calculation of matrix elements governing the neutrinoless double-beta decay (0νββ-decay). That will allow to determine masses of neutrinos once the 0νββ-decay, which occurs if the neutrino is a massive Majorana particle and the total lepton number is not onserved, will be observed. Experiments studying the 2νββ-decay are currently approaching a qualitatively new level, where high-precision measurements are performed not only for half-lives but for all other observables of the process. In this context an improved formula for the 2νββ-decay is presented. Further, a novel approach for determining the effective axial-vector coupling constant is proposed.

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