Articles de revues : « Data analysis, neutrinoless double beta decay »

1

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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Caminata, Alessio, Douglas Adams, Chris Alduino, Krystal Alfonso, Frank Avignone, Oscar Azzolini, Giacomo Bari et al. « Results from the Cuore Experiment † ». Universe 5, n^o 1 (2 janvier 2019) : 10. http://dx.doi.org/10.3390/universe5010010.

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The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO 2 crystals arranged in a cylindrical compact structure of 19 towers, each of them made of 52 crystals. The construction of the experiment was completed in August 2016 and the data taking started in spring 2017 after a period of commissioning and tests. In this work we present the neutrinoless double beta decay results of CUORE from examining a total TeO 2 exposure of 86.3 kg yr , characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts / ( keV kg yr ) . In this physics run, CUORE placed a lower limit on the decay half-life of neutrinoless double beta decay of 130 Te > 1.3 · 10 25 yr (90% C.L.). Moreover, an analysis of the background of the experiment is presented as well as the measurement of the 130 Te 2 ν β β decay with a resulting half-life of T 1 / 2 2 ν = [ 7.9 ± 0.1 ( stat . ) ± 0.2 ( syst . ) ] × 10 20 yr which is the most precise measurement of the half-life and compatible with previous results.

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Agostini, M., J. A. Detwiler, P. Finnerty, K. Kröninger, D. Lenz, J. Liu, M. G. Marino et al. « The MGDO software library for data analysis in Ge neutrinoless double-beta decay experiments ». Journal of Physics : Conference Series 375, n^o 4 (30 juillet 2012) : 042027. http://dx.doi.org/10.1088/1742-6596/375/1/042027.

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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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Verma, Rohit. « Lepton textures and neutrino oscillations ». International Journal of Modern Physics A 29, n^o 21 (20 août 2014) : 1444009. http://dx.doi.org/10.1142/s0217751x14440096.

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A systematic analysis of the textures arising in lepton mass matrices have been carried out using unitary transformations and condition of naturalness for the Dirac and Majorana neutrino possibilities. It is observed that the recent three neutrino oscillation data together with the effective mass in neutrinoless double beta decay provide vital clues in predicting the general structures of these lepton mass matrices.

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Belli, Pierluigi, R. Bernabei, V. B. Brudanin, F. Cappella, V. Caracciolo, R. Cerulli, F. A. Danevich et al. « Search for Double Beta Decay of 106Cd with an Enriched 106CdWO4 Crystal Scintillator in Coincidence with CdWO4 Scintillation Counters ». Universe 6, n^o 10 (16 octobre 2020) : 182. http://dx.doi.org/10.3390/universe6100182.

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Studies on double beta decay processes in 106Cd were performed by using a cadmium tungstate scintillator enriched in 106Cd at 66% (106CdWO4) with two CdWO4 scintillation counters (with natural Cd composition). No effect was observed in the data that accumulated over 26,033 h. New improved half-life limits were set on the different channels and modes of the 106Cd double beta decay at level of limT1/2∼1020−1022 yr. The limit for the two neutrino electron capture with positron emission in 106Cd to the ground state of 106Pd, T1/22νECβ+≥2.1×1021 yr, was set by the analysis of the 106CdWO4 data in coincidence with the energy release 511 keV in both CdWO4 counters. The sensitivity approaches the theoretical predictions for the decay half-life that are in the range T1/2∼1021−1022 yr. The resonant neutrinoless double-electron capture to the 2718 keV excited state of 106Pd is restricted at the level of T1/20ν2K≥2.9×1021 yr.

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Cappuzzello, Francesco, Luis Acosta, Clementina Agodi, Carmen Altana, Paulina Amador-Valenzuela, Ismail Boztosun, A. Brischetto Giuseppe et al. « Recent experimental activity on heavy-ion induced reactions within the NUMEN project ». EPJ Web of Conferences 252 (2021) : 04001. http://dx.doi.org/10.1051/epjconf/202125204001.

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The possibility to use a special class of heavy-ion induced direct reactions, such as double charge exchange reactions, is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The strategies adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud are briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis.

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Kitabayashi, Teruyuki, et Masaki Yasuè. « Seesaw model and two zero flavor neutrino texture ». International Journal of Modern Physics A 32, n^o 06n07 (8 mars 2017) : 1750034. http://dx.doi.org/10.1142/s0217751x17500348.

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In the two zero flavor neutrino mass matrix scheme with nonvanishing Majorana effective mass [Formula: see text] for the neutrinoless double beta decay, four textures are compatible with observed data. We obtain the complete list of the possible textures of four zero Dirac neutrino mass matrix [Formula: see text] in the seesaw mechanism providing these four flavor neutrino textures. Explicit analytical analysis of [Formula: see text] turns out to provide the relation of [Formula: see text].

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Civitarese, Osvaldo, Jouni Suhonen et Kai Zuber. « Combining data from high-energy pp-reactions and neutrinoless double-beta decay : Limits on the mass of the right-handed boson ». International Journal of Modern Physics E 25, n^o 10 (octobre 2016) : 1650081. http://dx.doi.org/10.1142/s0218301316500816.

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From the recently established lower-limits on the nonobservability of the neutrinoless double-beta decay of [Formula: see text]Ge (GERDA collaboration) and [Formula: see text]Xe (EXO-200 and KamLAND-Zen collaborations), combined with the ATLAS and CMS data, we extract limits for the left–right (LR) mixing angle, [Formula: see text], of the [Formula: see text] electroweak Hamiltonian. For the theoretical analysis, which is a model dependent, we have adopted a minimal extension of the Standard Model (SM) of Electroweak Interactions belonging to the [Formula: see text] representation. The nuclear-structure input of the analysis consists of a set of matrix elements and phase-space factors, and the experimental lower-limits for the half-lives. The other input are the ATLAS and CMS cross-section measurements of the [Formula: see text]-collisions into two-jets and two-leptons, performed at the large hadron collider (LHC). Our analysis yields the limit [Formula: see text] for [Formula: see text], by combining the model-dependent limits extracted from the double-beta-decay measurements and those extracted from the results of the CMS and ATLAS measurements.

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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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Cavallaro, M., C. Agodi, J. I. Bellone, S. Brasolin, G. A. Brischetto, M. P. Bussa, S. Calabrese et al. « A focus on selected perspectives of the NUMEN project ». Journal of Physics : Conference Series 2340, n^o 1 (1 septembre 2022) : 012036. http://dx.doi.org/10.1088/1742-6596/2340/1/012036.

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Abstract The use of double charge exchange reactions is discussed in view of their application to extract information that may be helpful to determinate the nuclear matrix elements entering in the expression of neutrinoless double beta decay half-life. The strategy adopted in the experimental campaigns performed at INFN - Laboratori Nazionali del Sud and in the analysis methods within the NUMEN project is briefly described, emphasizing the advantages of the multi-channel approach to nuclear reaction data analysis. An overview on the research and development activities on the MAGNEX magnetic spectrometer is also given, with a focus on the chosen technological solutions for the focal plane detector which will guarantee the performances at high-rate conditions.

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Adhikari, G., S. Al Kharusi, E. Angelico, G. Anton, I. J. Arnquist, I. Badhrees, J. Bane et al. « nEXO : neutrinoless double beta decay search beyond 10²⁸ year half-life sensitivity ». Journal of Physics G : Nuclear and Particle Physics 49, n^o 1 (3 décembre 2021) : 015104. http://dx.doi.org/10.1088/1361-6471/ac3631.

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Abstract The nEXO neutrinoless double beta (0νββ) decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon to search for the decay in 136Xe. Progress in the detector design, paired with higher fidelity in its simulation and an advanced data analysis, based on the one used for the final results of EXO-200, produce a sensitivity prediction that exceeds the half-life of 1028 years. Specifically, improvements have been made in the understanding of production of scintillation photons and charge as well as of their transport and reconstruction in the detector. The more detailed knowledge of the detector construction has been paired with more assays for trace radioactivity in different materials. In particular, the use of custom electroformed copper is now incorporated in the design, leading to a substantial reduction in backgrounds from the intrinsic radioactivity of detector materials. Furthermore, a number of assumptions from previous sensitivity projections have gained further support from interim work validating the nEXO experiment concept. Together these improvements and updates suggest that the nEXO experiment will reach a half-life sensitivity of 1.35 × 1028 yr at 90% confidence level in 10 years of data taking, covering the parameter space associated with the inverted neutrino mass ordering, along with a significant portion of the parameter space for the normal ordering scenario, for almost all nuclear matrix elements. The effects of backgrounds deviating from the nominal values used for the projections are also illustrated, concluding that the nEXO design is robust against a number of imperfections of the model.

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Klimenko, A. A., et N. S. Rumyantseva. « Limits of Majorana neutrino mass from combined analysis of data from 76Ge and 136Xe neutrinoless double beta decay experiments ». Physics of Particles and Nuclei 48, n^o 1 (janvier 2017) : 21–26. http://dx.doi.org/10.1134/s1063779616060125.

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Di Marcello, V., A. Ianni et G. Panella. « Numerical analysis of radon behavior in radon-suppressed clean room environments ». Journal of Instrumentation 17, n^o 06 (1 juin 2022) : P06033. http://dx.doi.org/10.1088/1748-0221/17/06/p06033.

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Abstract Radon-free clean rooms are essential for the production and assembly of components adopted in low-background experiments. In particular, long-lived radon decay products are often problematic for rare events searches, such as low energy neutrino interactions, direct dark matter detection, and neutrinoless double beta decay. These isotopes can easily deposit onto surfaces exposed to radon, leading to a residual background that can limit the sensitivity of experiments. In order to mitigate this background source, construction of detectors in radon-reduced environments is essential. In this framework, design and building of radon-suppressed clean rooms require a deep understanding of the radon behavior and the different sources of contamination. In the paper, computation fluid-dynamics (CFD) analyses of the radon-suppressed clean rooms built for the DarkSide-50 experiment are reported. The numerical model including the main radon contributions, such as structural materials, equipment, and operators activity, provides very promising results in a remarkable agreement with available experimental data, confirming the validity of the current modelling approach for future applications.

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Li, Aobo. « KamLAND-Zen 800 Status and Prospect with the Artificial Intelligence Powered Analysis ». Journal of Physics : Conference Series 2156, n^o 1 (1 décembre 2021) : 012114. http://dx.doi.org/10.1088/1742-6596/2156/1/012114.

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Abstract The discovery of neutrinoless double beta decay (0υββ) would shed light on the persistent puzzle surrounding the origin of neutrino mass and help explain the matter-dominated universe. KamLAND-Zen is one of the leading experiments searching for 0υββ. The first phase of the experiment, called KamLAND-Zen 400, set a world-leading limit on 0υββ lifetime. After the conclusion of KamLAND-Zen 400, a brand new mini-balloon with a larger volume and cleaner surface were instrumented to contain 745 kg of 136Xe. Since Jan. 2019, KamLAND-Zen 800 has started data-taking and aims to improve on the previous 0υββ result. A detailed study of the backgrounds in this new data will be presented along with a state-of-the-art approach for classifying backgrounds using a new algorithm called KamNet. The rejection power of KamNet does not rely on coincidence tagging and scales with hardware updates. With the help of KamNet, the 0υββ sensitivity of KamLAND-Zen 800 is significantly enhanced to a new summit.

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Schwarz, Mario, Patrick Krause, Andreas Leonhardt, Laszlo Papp, Stefan Schönert, Christoph Wiesinger, Maria Fomina et al. « Liquid Argon Instrumentation and Monitoring in LEGEND-200 ». EPJ Web of Conferences 253 (2021) : 11014. http://dx.doi.org/10.1051/epjconf/202125311014.

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LEGEND is the next-generation experiment searching for the neutrinoless double beta decay in 76Ge. The first stage, LEGEND-200, takes over the cryogenic infrastructure of GERDA at LNGS: an instrumented water tank surrounding a 64 m3 liquid argon cryostat. Around 200 kg of Ge detectors will be deployed in the cryostat, with the liquid argon acting as cooling medium, high-purity passive shielding and secondary detection medium. For the latter purpose, a liquid argon instrumentation is developed, based on the system used in GERDA Phase II. Wavelength shifting fibers coated with TPB are arranged in two concentric barrels. Both ends are read out by SiPM arrays. A wavelength shifting reflector surrounds the array in order to enhance the light collection far from the array. The LLAMA is installed in the cryostat to permanently monitor the optical parameters and to provide in-situ inputs for modeling purposes. The design of all parts of the LEGEND-200 LAr instrumentation is presented. An overview of the geometry, operation principle, and off-line data analysis of the LLAMA is shown.

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Campani, A., D. Q. Adams, C. Alduino, K. Alfonso, F. T. Avignone, O. Azzolini, G. Bari et al. « Status and results from the CUORE experiment ». International Journal of Modern Physics A 35, n^o 36 (23 décembre 2020) : 2044016. http://dx.doi.org/10.1142/s0217751x20440169.

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The Cryogenic Underground Observatory for Rare Events (CUORE) is a tonne-scale cryogenic experiment located at the Laboratori Nazionali del Gran Sasso that exploits bolometric technique to search for neutrinoless double beta decay [Formula: see text] of [Formula: see text]Te. The detector consists of a segmented array of 988 natural [Formula: see text] cubic crystals arranged in a cylindrical compact structure of 19 towers. The detector construction was completed in August 2016 and data taking started in Spring 2017. In this work, we present a brief description of the bolometric technique for rare events search and the CUORE detector, then we concentrate on the data analysis results. In this respect, we focus on the procedure for data processing and on the first [Formula: see text] results we obtained from a total [Formula: see text] exposure of [Formula: see text]. Next, we illustrate the main background sources and the CUORE background model, from which we obtain the most precise measurement of [Formula: see text]Te [Formula: see text] half-life to date. Finally, we discuss the improvements achieved with 2018 and 2019 detector optimization campaigns and the current perspectives of our experiment.

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Adams, D. Q., C. Alduino, K. Alfonso, F. T. Avignone, O. Azzolini, G. Bari, F. Bellini et al. « An energy-dependent electro-thermal response model of CUORE cryogenic calorimeter ». Journal of Instrumentation 17, n^o 11 (1 novembre 2022) : P11023. http://dx.doi.org/10.1088/1748-0221/17/11/p11023.

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Abstract The Cryogenic Underground Observatory for Rare Events (CUORE) is the most sensitive experiment searching for neutrinoless double-beta decay (0νββ) in 130Te. CUORE uses a cryogenic array of 988 TeO2 calorimeters operated at ∼10 mK with a total mass of 741 kg. To further increase the sensitivity, the detector response must be well understood. Here, we present a non-linear thermal model for the CUORE experiment on a detector-by-detector basis. We have examined both equilibrium and dynamic electro-thermal models of detectors by numerically fitting non-linear differential equations to the detector data of a subset of CUORE channels which are well characterized and representative of all channels. We demonstrate that the hot-electron effect and electric-field dependence of resistance in NTD-Ge thermistors alone are inadequate to describe our detectors' energy-dependent pulse shapes. We introduce an empirical second-order correction factor in the exponential temperature dependence of the thermistor, which produces excellent agreement with energy-dependent pulse shape data up to 6 MeV. We also present a noise analysis using the fitted thermal parameters and show that the intrinsic thermal noise is negligible compared to the observed noise for our detectors.

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Gariazzo, Stefano, Martina Gerbino, Thejs Brinckmann, Massimiliano Lattanzi, Olga Mena, Thomas Schwetz, Shouvik Roy Choudhury et al. « Neutrino mass and mass ordering : no conclusive evidence for normal ordering ». Journal of Cosmology and Astroparticle Physics 2022, n^o 10 (1 octobre 2022) : 010. http://dx.doi.org/10.1088/1475-7516/2022/10/010.

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Abstract The extraction of the neutrino mass ordering is one of the major challenges in particle physics and cosmology, not only for its implications for a fundamental theory of mass generation in nature, but also for its decisive role in the scale of future neutrinoless double beta decay experimental searches. It has been recently claimed that current oscillation, beta decay and cosmological limits on the different observables describing the neutrino mass parameter space provide robust decisive Bayesian evidence in favor of the normal ordering of the neutrino mass spectrum [1]. We further investigate these strong claims using a rich and wide phenomenology, with different sampling techniques of the neutrino parameter space. Contrary to the findings of Jimenez et al. [1], no decisive evidence for the normal mass ordering is found. Neutrino mass ordering analyses must rely on priors and parameterizations that are ordering-agnostic: robust results should be regarded as those in which the preference for the normal neutrino mass ordering is driven exclusively by the data, while we find a difference of up to a factor of 33 in the Bayes factors among the different priors and parameterizations exploited here. An ordering-agnostic prior would be represented by the case of parameterizations sampling over the two mass splittings and a mass scale, or those sampling over the individual neutrino masses via normal prior distributions only. In this regard, we show that the current significance in favor of the normal mass ordering should be taken as 2.7σ (i.e. moderate evidence), mostly driven by neutrino oscillation data. Let us stress that, while current data favor NO only mildly, we do not exclude the possibility that this may change in the future. Eventually, upcoming oscillation and cosmological data may (or may not) lead to a more significant exclusion of IO.

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Benaoum, H. B., et S. H. Shaglel. « TeV-scale resonant leptogenesis with new scaling ansatz on neutrino Dirac mass matrix from A4 flavor symmetry ». International Journal of Modern Physics A 35, n^o 17 (12 juin 2020) : 2050077. http://dx.doi.org/10.1142/s0217751x20500773.

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We propose a new scaling ansatz in the neutrino Dirac mass matrix to explain the low energy neutrino oscillations data, baryon number asymmetry and neutrinoless double beta decay. In this work, a full reconstruction of the neutrino Dirac mass matrix has been realized from the low energy neutrino oscillations data based on type-I seesaw mechanism. A concrete model based on [Formula: see text] flavor symmetry has been considered to generate such a neutrino Dirac mass matrix and imposes a relation between the two scaling factors. In this model, the right-handed Heavy Majorana neutrino masses are quasi-degenerate at TeV mass scales. Extensive numerical analysis studies have been carried out to constrain the parameter space of the model from the low energy neutrino oscillations data. It has been found that the parameter space of the Dirac mass matrix elements lies near or below the MeV region and the scaling factor [Formula: see text] has to be less than 10. Furthermore, we have examined the possibility for simultaneous explanation of both neutrino oscillations data and the observed baryon number asymmetry in the Universe. Such an analysis gives further restrictions on the parameter space of the model, thereby explaining the correct neutrino data as well as the baryon number asymmetry via a resonant leptogenesis scenario. Finally, we show that the allowed space for the effective Majorana neutrino mass [Formula: see text] is also constrained in order to account for the observed baryon asymmetry.

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Ghosh, Gayatri. « Significance of Broken μ − τ Symmetry in Correlating δ CP , θ 13 , Lightest Neutrino Mass, and Neutrinoless Double Beta Decay 0 ν β β ». Advances in High Energy Physics 2021 (20 mars 2021) : 1–23. http://dx.doi.org/10.1155/2021/9563917.

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Leptonic CP violating phase δ CP in the light neutrino sector and leptogenesis via present matter-antimatter asymmetry of the Universe entails each other. Probing CP violation in light neutrino oscillation is one of the challenging tasks today. The reactor mixing angle θ 13 measured in reactor experiments, LBL, and DUNE with high precision in neutrino experiments indicates towards the vast dimensions of scope to detect δ CP . The correlation between leptonic Dirac CPV phase δ CP , reactor mixing angle θ 13 , lightest neutrino mass m 1 , and matter-antimatter asymmetry of the Universe within the framework of μ − τ symmetry breaking assuming the type I seesaw dominance is extensively studied here. Here, a SO(10) GUT model with flavor μ − τ symmetry is considered. In this work, the idea is to link baryogenesis through leptogenesis and the hint of CP violation in the neutrino oscillation data to a breaking of the mu-tau symmetry. Small tiny breaking of the μ − τ symmetry allows a large Dirac CP violating phase in neutrino oscillation which in turn is characterized by awareness of measured value of θ 13 and to provide a hint towards a better understanding of the experimentally observed near-maximal value of ν μ − ν τ mixing angle θ 23 ≃ π / 4 . Precise breaking of the μ − τ symmetry is achieved by adding a 120-plet Higgs to the 10 + 1 2 ¯ 6 -dimensional representation of Higgs. The estimated three-dimensional density parameter space of the lightest neutrino mass m 1 , δ CP , and reactor mixing angle θ 13 is constrained here for the requirement of producing the observed value of baryon asymmetry of the Universe through the mechanism of leptogenesis. Carrying out numerical analysis, the allowed parameter space of m 1 , δ CP , and θ 13 is found out which can produce the observed baryon to photon density ratio of the Universe.

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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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Damanik, Asan. « Neutrino masses from modified bimaximal mixing ». Modern Physics Letters A 30, n^o 32 (5 octobre 2015) : 1550169. http://dx.doi.org/10.1142/s0217732315501692.

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The bimaximal (BM) neutrino mixing matrix was formulated in order to accommodate the data of the experimental results which indicate that both solar and atmospheric neutrino oscillation in vacuum are near maximal. But, after the T2K and Daya Bay Collaborations reported that the mixing angle [Formula: see text] is nonzero and relatively large, many authors have modified the neutrino mixing matrix in order to accommodate experimental data. We modified the BM mixing matrix by introducing a simple perturbation matrix into BM mixing matrix. The modified BM mixing matrix can proceed the mixing angles which are compatible with the global fit analysis data and by imposing the [Formula: see text]–[Formula: see text] symmetry into mass matrix from modified BM, we have the neutrino mass in normal hierarchy (NH): [Formula: see text]. Using the neutrino masses that obtained from neutrino mass matrix in the scheme of modified BM and imposing the constraint exact [Formula: see text] symmetry into neutrino mass matrix, we cannot have compatible squared-mass differences for both [Formula: see text] and [Formula: see text] as dictated by experimental results. In order to proceed the neutrino masses that can predict correctly the squared-mass difference, we introduce a small parameter [Formula: see text] into neutrino mass matrix. The obtained neutrino masses are in agreement with the squared-mass difference as dictated by experimental results. The predicted neutrino effective mass: [Formula: see text] in this paper can be tested in the future neutrinoless double beta decay.

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Cattadori, Carla Maria, et Francesco Salamida. « GERDA and LEGEND : Probing the Neutrino Nature and Mass at 100 meV and beyond ». Universe 7, n^o 9 (25 août 2021) : 314. http://dx.doi.org/10.3390/universe7090314.

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The Gerda (GERmanium Detector Array) project, located at Laboratori Nazionali del Gran Sasso (LNGS), was started in 2005, a few years after the claim of evidence for the neutrinoless double beta decay (0νββ) of 76Ge to the ground state of 76Se: it is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a measurement of its mass and mass hierarchy. The aim of Gerda was to confirm or disprove the claim by an increased sensitivity experiment. After establishing the new technology of Ge detectors operated bare in liquid Argon and since 2011, Gerda efficiently collected data searching for 0νββ of 76Ge, first deploying the 76Ge-enriched detectors from two former experiments and later new detectors with enhanced signal-to-background rejection, produced from freshly 76Ge-enriched material. Since then, the Gerda setup has been upgraded twice, first in 2013–2015 and later in 2018. The period before 2013 is Phase I and that after 2015 is Phase II. Both the Gerda setup and the analysis tools evolved along the project lifetime, allowing to achieve the remarkable average energy resolution of ∼3.6 and ∼2.6 keV for Coaxial Germanium (Coax) detectors and for Broad Energy Germanium (BEGe), respectively, and the background index of 5.2−1.3+1.6 · 10−4 cts/(keV·kg·yr) in a 230 keV net range centered at Qββ. No evidence of the 0νββ decay at Qββ = 2039.1 keV has been found, hence the limit of 1.8·1026 yr on the half-life (T1/20ν) at 90% C.L. was set with the exposure of 127.2 kg·yr. The corresponding limit range for the effective Majorana neutrino mass mee has been set to 79–180 meV. The Gerda performances in terms of background index, energy resolution and exposure are the best achieved so far by 76Ge double beta decay experiments. In Phase II, Gerda succeeded in operating in a background free regime and set a world record. In 2017, the Legend Collaboration was born from the merging of the Gerda and Majorana Collaborations and resources with the aim to further improve the Gerda sensitivity. First, the Legend200 project, with a mass of up to 200 kg of 76Ge-enriched detectors, aims to further improve the background index down to <0.6 · 10−3 cts/(keV·kg·yr) to explore the Inverted Hierarchy region of the neutrino mass ordering, then the Legend1000 (1 ton of 76Ge-enriched) will probe the Normal Hierarchy. In this paper, we describe the Gerda experiment, its evolution, the data analysis flow, a selection of its results and technological achievements, and finally the design, features and challenges of Legend, the Gerda prosecutor.

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Garfagnini, Alberto. « Neutrinoless double beta decay experiments ». International Journal of Modern Physics : Conference Series 31 (janvier 2014) : 1460286. http://dx.doi.org/10.1142/s2010194514602865.

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Neutrinoles double beta decay is the only process known so far able to test the neutrino intrinsic nature: its experimental observation would imply that the lepton number is violated by two units and prove that neutrinos have a Majorana mass components, being their own anti-particle. While several experiments searching for such a rare decay have been performed in the past, a new generation of experiments using different isotopes and techniques have recently released their results or are raking data and will provide new limits, should no signal be observed, in the next few years to come. The present contribution reviews the latest public results on double beta decay searches and gives an overview on the expected sensitivities of the experiments in construction which will be able to set stronger limits in the near future.

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KLAPDOR-KLEINGROTHAUS, H. V., A. DIETZ, H. L. HARNEY et I. V. KRIVOSHEINA. « EVIDENCE FOR NEUTRINOLESS DOUBLE BETA DECAY ». Modern Physics Letters A 16, n^o 37 (7 décembre 2001) : 2409–20. http://dx.doi.org/10.1142/s0217732301005825.

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The data of the Heidelberg–Moscow double beta decay experiment for the measuring period August 1990–May 2000 (54.9813 kg y or 723.44 molyears), published recently, are analyzed using the potential of the Bayesian method for low counting rates. First evidence for neutrinoless double beta decay is observed giving first evidence for lepton number violation. The evidence for this decay mode is 97% (2.2σ) with the Bayesian method, and 99.8% c.l. (3.1σ) with the method recommended by the Particle Data Group. The half-life of the process is found with the Bayesian method to be [Formula: see text] (95% c.l.) with a best value of 1.5 × 1025 y . The deduced value of the effective neutrino mass is, with the nuclear matrix elements from Ref. 1, <m> = (0.11–0.56) eV (95% c.l.), with a best value of 0.39 eV. Uncertainties in the nuclear matrix elements may widen the range given for the effective neutrino mass by at most a factor 2. Our observation which at the same time means evidence that the neutrino is a Majorana particle, will be of fundamental importance for neutrino physics.

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MATSUDA, KOICHI, TATSURU KIKUCHI, TAKESHI FUKUYAMA et HIROYUKI NISHIURA. « CONSTRAINTS FROM NEUTRINOLESS DOUBLE BETA DECAY ». Modern Physics Letters A 17, n^o 39 (21 décembre 2002) : 2597–603. http://dx.doi.org/10.1142/s0217732302009362.

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We examine the constraints from the recent HEIDELBERG–MOSCOW double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. In this scenario, we obtain possible upper bounds for the Majorana CP violating phase in the lepton sector by incorporating the data from the neutrino oscillation, the single beta decay experiments, and from the astrophysical observation. We also predict the neutrino mass that may be measurable in the future beta decay experiments.

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Dell’Oro, Stefano, Simone Marcocci, Matteo Viel et Francesco Vissani. « Neutrinoless Double Beta Decay : 2015 Review ». Advances in High Energy Physics 2016 (2016) : 1–37. http://dx.doi.org/10.1155/2016/2162659.

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The discovery of neutrino masses through the observation of oscillations boosted the importance of neutrinoless double beta decay (0νββ). In this paper, we review the main features of this process, underlining its key role from both the experimental and theoretical point of view. In particular, we contextualize the0νββin the panorama of lepton number violating processes, also assessing some possible particle physics mechanisms mediating the process. Since the0νββexistence is correlated with neutrino masses, we also review the state of the art of the theoretical understanding of neutrino masses. In the final part, the status of current0νββexperiments is presented and the prospects for the future hunt for0νββare discussed. Also, experimental data coming from cosmological surveys are considered and their impact on0νββexpectations is examined.

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BILENKY, S. M., et C. GIUNTI. « NEUTRINOLESS DOUBLE-BETA DECAY : A BRIEF REVIEW ». Modern Physics Letters A 27, n^o 13 (30 avril 2012) : 1230015. http://dx.doi.org/10.1142/s0217732312300157.

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In this brief review we discuss the generation of Majorana neutrino masses through the seesaw mechanism, the theory of neutrinoless double-beta decay, the implications of neutrino oscillation data for the effective Majorana mass, taking into account the recent Daya Bay measurement of ϑ13, and the interpretation of the results of neutrinoless double-beta decay experiments.

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Vergados, J. D., H. Ejiri et F. Šimkovic. « Neutrinoless double beta decay and neutrino mass ». International Journal of Modern Physics E 25, n^o 11 (novembre 2016) : 1630007. http://dx.doi.org/10.1142/s0218301316300071.

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The observation of neutrinoless double beta decay (DBD) will have important consequences. First it will signal that lepton number is not conserved and the neutrinos are Majorana particles. Second, it represents our best hope for determining the absolute neutrino mass scale at the level of a few tens of meV. To achieve the last goal, however, certain hurdles have to be overcome involving particle, nuclear and experimental physics. Particle physics is important since it provides the mechanisms for neutrinoless DBD. In this review, we emphasize the light neutrino mass mechanism. Nuclear physics is important for extracting the useful information from the data. One must accurately evaluate the relevant nuclear matrix elements (NMEs), a formidable task. To this end, we review the recently developed sophisticated nuclear structure approaches, employing different methods and techniques of calculation. We also examine the question of quenching of the axial vector coupling constant, which may have important consequences on the size of the NMEs. From an experimental point of view it is challenging, since the life times are extremely long and one has to fight against formidable backgrounds. One needs large isotopically enriched sources and detectors with good energy resolution and very low background.

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AALSETH, C. E., F. T. AVIGNONE, A. BARABASH, F. BOEHM, R. L. BRODZINSKI, J. I. COLLAR, P. J. DOE et al. « COMMENT ON "EVIDENCE FOR NEUTRINOLESS DOUBLE BETA DECAY" ». Modern Physics Letters A 17, n^o 22 (20 juillet 2002) : 1475–78. http://dx.doi.org/10.1142/s0217732302007715.

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We comment on the recent claim for the experimental observation of neutrinoless double-beta decay. We discuss several limitations in the analysis provided in that paper and conclude that there is no basis for the presented claim.

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Agostini, M., A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, E. Bellotti et al. « Searching Neutrinoless Double Beta Decay with Gerda Phase II ». International Journal of Modern Physics : Conference Series 46 (janvier 2018) : 1860040. http://dx.doi.org/10.1142/s2010194518600406.

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An observation of neutrinoless double beta ([Formula: see text]) decay would allow to shed light onto the nature of neutrinos. Gerda (GERmanium Detector Array) aims to discover this process in a background-free search using [Formula: see text]Ge. The experiment is located at the Laboratori Nazionali del Gran Sasso (LNGS) of the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. Bare, isotopically enriched, high purity germanium detectors are operated in liquid argon. Gerda follows a staged approach. In Phase II 35.6 kg of enriched germanium detectors are operated since December 2015. The application of active background rejection methods, such as a liquid argon scintillation light read-out and pulse shape discrimination of germanium detector signals, allows to reduce the background index to the intended level of [Formula: see text] cts/(keV⋅kg⋅yr). No evidence for the [Formula: see text] decay has been found in 23.2 kg⋅yr of Phase II data, and together with data from Phase I the up-to-date most stringent half-life limit for this process in [Formula: see text]Ge has been established, at a median sensitivity of 5.8⋅10[Formula: see text][Formula: see text]yr the 90[Formula: see text]% C.L. lower limit is 8.0⋅10[Formula: see text][Formula: see text]yr.

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SUHONEN, JOUNI, et MARKUS KORTELAINEN. « NUCLEAR MATRIX ELEMENTS FOR DOUBLE BETA DECAY ». International Journal of Modern Physics E 17, n^o 01 (janvier 2008) : 1–11. http://dx.doi.org/10.1142/s0218301308009495.

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The neutrinoless double beta (0νββ) decay of atomic nuclei plays a key role in the search for massive Majorana neutrinos and their mass scale. To extract the necessary information from the measured data the nuclear-structure effects have to be accounted for by computation of the associated nuclear matrix elements (NME's). In this article the NME's for the light-neutrino exchange mechanism are discussed. They are computed by using the proton-neutron quasiparticle random-phase approximation (pnQRPA). Recent developments in this field relate to the handling of the nucleon-nucleon short-range correlations and independent experimental probes of the wave functions relevant for the NME's.

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Zhang, Jue. « Neutrino mass ordering in future neutrinoless double beta decay experiments ». Modern Physics Letters A 31, n^o 22 (14 juillet 2016) : 1630020. http://dx.doi.org/10.1142/s0217732316300202.

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Motivated by recent intensive experimental efforts on searching for neutrinoless double beta decays, we present a detailed quantitative analysis on the prospect of resolving neutrino mass ordering in the next generation [Formula: see text]Ge-type experiments.

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Schmidt, B. « First data from the CUPID-Mo neutrinoless double beta decay experiment ». Journal of Physics : Conference Series 1468 (février 2020) : 012129. http://dx.doi.org/10.1088/1742-6596/1468/1/012129.

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MACOLINO, CARLA. « RESULTS ON NEUTRINOLESS DOUBLE-BETA DECAY FROM GERDA PHASE I ». Modern Physics Letters A 29, n^o 01 (7 janvier 2014) : 1430001. http://dx.doi.org/10.1142/s0217732314300018.

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The GERmanium Detector Array, GERDA, is designed to search for neutrinoless double-beta (0νββ) decay of 76 Ge and it is installed in the Laboratori Nazionali del Gran Sasso (LNGS) of INFN, Italy. In this review, the detection principle and detector setup of GERDA are described. Also, the main physics results by GERDA Phase I, are discussed. They include the measurement of the half-life of 2νββ decay, the background decomposition of the energy spectrum and the techniques for the discrimination of the background, based on the pulse shape of the signal. In the last part of this review, the estimation of a limit on the half-life of 0νββ ([Formula: see text] at 90% C.L.) and the comparison with previous results are discussed. GERDA data from Phase I strongly disfavor the recent claim of 0νββ discovery, based on data from the Heidelberg–Moscow experiment.

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Krause, P. « GERDA : Final Results and Physics Beyond Neutrinoless Double-Beta Decay ». Journal of Physics : Conference Series 2156, n^o 1 (1 décembre 2021) : 012117. http://dx.doi.org/10.1088/1742-6596/2156/1/012117.

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Abstract The GERDA experiment searched for the lepton number violating neutrinoless double-beta 0υββ decay of 76 Ge. Observation of this decay would provide answers to fundamental problems in particle physics and cosmology, including the origin of neutrino masses and baryon asymmetry in the universe. The GERDA experiment achieved the most stringent lower limit on the half-life of the 0υββ decay of 1.8 • 1026 yr at 90% C.L. (which coincides with the sensitivity) by operating high-purity germanium (HPGe) detectors enriched in 76Ge submerged in liquid argon (LAr). The collaboration could achieve this breakthrough by reducing the background event rate to 5.2 • 10–4 counts/(keV kg yr) at the end-point energy. This unprecedented background index could be achieved by developing unique technologies like utilizing the scintillation light of the LAr to reject efficiently background events that deposit energy simultaneously in the HPGe detectors and in LAr, and the pulse shape discrimination which exploits specific event topologies of backgrounds and signal candidates. Due to the ultra-low background approach the GERDA data is also suited for other rare event searches beyond the 0υββ decay like the search for super-WIMPs.

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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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Ali, A., A. V. Borisov et D. V. Zhuridov. « Mechanisms of neutrinoless double-beta decay : A comparative analysis of several nuclei ». Physics of Atomic Nuclei 73, n^o 12 (décembre 2010) : 2083–96. http://dx.doi.org/10.1134/s1063778810120136.

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Fritzsch, Harald. « Oscillating Neutrinos and Majorana Neutrino Masses ». Universe 6, n^o 2 (6 février 2020) : 29. http://dx.doi.org/10.3390/universe6020029.

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We discuss the mass matrices with texture zeros for the quarks and leptons. The flavor mixing angles for the quarks are functions of the quark masses and can be calculated. The results agree with the experimental data. The texture zero mass matrices for the leptons and the see-saw mechanism are used to derive relations between the matrix elements of the lepton mixing matrix and the ratios of the neutrino masses. Using the measured neutrino mass differences, the neutrino masses can be calculated. The neutrinoless double beta decay is discussed. The effective Majorana neutrino mass, describing the neutrinoless double beta decay, can be calculated—it is about 4.6 meV. The present experimental limit is at least twenty times larger.

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GÓŹDŹ, MAREK, et WIESŁAW A. KAMIŃSKI. « NEUTRINOLESS DOUBLE BETA DECAY CONSTRAINED BY THE EXISTENCE OF LARGE EXTRA DIMENSIONS ». International Journal of Modern Physics E 13, n^o 01 (février 2004) : 367–70. http://dx.doi.org/10.1142/s021830130400220x.

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We present the possible influence on the half-life of neutrinoless double beta decay coming from the existence of n extra spatial dimensions. The half-life in question depends on the mass of the electron neutrino. We base our analysis on the Majorana neutrino mass mechanism in Arkani-Hamed–Dimopoulos–Dvali model.

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Gayer, Udo, Volker Werner, Tobias Beck, Sean Finch, Jörn Kleemann, Krishichayan, Bastian Löher et al. « Nuclear structure of 82Kr and 82Se relevant for neutrinoless double-beta decay ». EPJ Web of Conferences 194 (2018) : 02004. http://dx.doi.org/10.1051/epjconf/201819402004.

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Nuclear Resonance Fluorescence (NRF) experiments on the nuclei 82Kr and 82Se were performed, that are a candidates for a mother-daughter pair for the hypothetical neutrinoless double-beta (0νββ) decay. The experiment aimed at providing high-precision data to benchmark theoretical calculations of the nuclear matrix elements involved in this exotic decay mode. We have investigated the excitation energy range from 2.3MeV to 4.2MeV, where the nuclear scissors mode is expected to be located in nuclei of this mass region. Our experiment was able to constrain decay branches of the scissors mode down to a level of a few percents, comparable to previous experiments on heavy deformed 0νββ decay candidates. Reduced transition strengths of the magnetic dipole-excited states have been determined by a method that exploits the non-resonant background in the NRF spectra. They are compared to a calculation within the nuclear shell model for 82Se, which reveals their mixed orbital and spin character, hinting at a more complex microscopic structure of low-lying 1+ states.

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KLAPDOR-KLEINGROTHAUS, H. V. « LESSONS AFTER THE EVIDENCE FOR NEUTRINOLESS DOUBLE BETA DECAY — THE NEXT STEP ». International Journal of Modern Physics E 17, n^o 03 (mars 2008) : 505–17. http://dx.doi.org/10.1142/s0218301308009823.

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This paper describes the lessons we have to draw after the observation of neutrinoless ββ decay by the enriched 76 Ge experiment, for present and future experiments so as (a) to fulfill the task to confirm the present result (b) to deliver additional information on the main contributions of effective neutrino mass and right-handed weak currents etc. to the 0νββ amplitude. It is shown that presently running and planned experiments are probably not sensitive enough to check the evidence on a reasonable time scale. It is further demonstrated that, the only way to get more information on the individual contributions of m, η, λ etc. to the 0νββ amplitude is to go to completely different types of experiments, rather than those under construction and preparation at present, e.g. to mixed-mode β+/ EC decay experiments, such as 124 Xe decay. It is pointed out that the sometimes observed "tension" between the result of 0νββ decay and cosmological experiments like WMAP, SDSS etc. does not exist and is an artificial product of improper analysis of the latter.

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Gargano, Angela, Luigi Coraggio, Luca De Angelis, Tokuro Fukui et Nunzio Itaco. « Realistic shell model description of beta decay ». EPJ Web of Conferences 194 (2018) : 02007. http://dx.doi.org/10.1051/epjconf/201819402007.

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In this paper, we extend our previous realistic shell-model study of Gamow-Teller strengths and double-β decay properties for nuclei around 132Sn to lighter mass nuclei. The effective shell-model Hamiltonian and transition operators are microscopically derived by way of many-body perturbation theory, without resorting to empirical parameters. Our main aim is to further check the reliability of our approach and verify its stability in other mass regions. Calculated energy spectra as well as electric-quadrupole and β-decay properties are presented for 76Ge and 82Se and compared with the experimental data, together with some results for 130Te and 136Xe already reported in our previous paper. Finally, some preliminary results of nuclear matrix elements responsible for the neutrinoless double beta decay, calculated by using the bare operator, are shown.

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Pascoli, S., et S. T. Petcov. « The SNO solar neutrino data, neutrinoless double beta-decay and neutrino mass spectrum ». Physics Letters B 544, n^o 3-4 (septembre 2002) : 239–50. http://dx.doi.org/10.1016/s0370-2693(02)02510-8.

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Campani, Alice, Valentina Dompè et Guido Fantini. « Status and Perspectives on Rare Decay Searches in Tellurium Isotopes ». Universe 7, n^o 7 (26 juin 2021) : 212. http://dx.doi.org/10.3390/universe7070212.

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Neutrinoless double beta decay (0νββ) is a posited lepton number violating decay whose search is an increasingly active field in modern astroparticle physics. A discovery would imply neutrinos are Majorana particles and inform neutrino physics, cosmology and beyond-standard-model theories. Among the few nuclei where double beta decay (ββ) is allowed, tellurium isotopes stand for their high natural abundance and are currently employed in multiple experiments. The search for 0νββ will provide large exposure data sets in the coming years, paving the way for unprecedented sensitivities. We review the latest rare decay searches in tellurium isotopes and compare past results with theories and prospects from running experiments.

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Zolotarova, A., I. C. Bandac, A. S. Barabash, V. Berest, L. Bergé, Ch Bourgeois, J. M. Calvo-Mozota et al. « The neutrinoless double beta decay CROSS experiment : demonstrator with surface sensitive bolometers ». Journal of Physics : Conference Series 2156, n^o 1 (1 décembre 2021) : 012157. http://dx.doi.org/10.1088/1742-6596/2156/1/012157.

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Abstract The CROSS experiment is proposing to use a new technology of surface sensitive bolometers for low-background neutrinoless double beta decay searches. Efficient rejection of surface α and β events will allow to reach background in the region of interest below than 10−4 cnts/keV/kg/yr. The isotopes of interest, which are 130Te and 100Mo, are investigated with TeO2 and Li2MoO4 bolometers. The surface sensitivity is achieved thanks to the evaporation of thin metallic film on the crystal surface that modifies the pulse shape of near-surface events. An investigation of various pulse shape parameters was performed. The analysis shows that one of the best parameters for discrimination is the integrated area of the raw signal both for TeO2 and Li2MoO4 with Pd-Al (10 nm - 100 nm) bi-layer.

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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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Bednyakov, V. A., V. B. Brudanin, S. G. Kovalenko et Ts D. Vylov. « On Prospects for Exploration of Supersymmetry in Double Beta Decay Experiments ». Modern Physics Letters A 12, n^o 04 (10 février 1997) : 233–41. http://dx.doi.org/10.1142/s0217732397000236.

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We analyze constraints on the parameters of the Rp violating supersymmetry ([Formula: see text] SUSY) which can be extracted from non-observation of the neutrinoless nuclear double beta decay (0νββ) at a given half-life lower bound. Our analysis covers a large class of phenomenologically viable [Formula: see text] SUSY models. We introduce special characteristics: the SUSY sensitivity of a ββ-decaying isotope and the SUSY reach of a 0νββ-experiment. The former provides a physical criterion for a selection of the most promising isotopes for SUSY searches and the latter gives a measure of success for a 0νββ-experiment in exploring the [Formula: see text] SUSY parameter space. On this basis we discuss prospects for exploration of supersymmetry in various 0νββ-experiments.

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