scholarly journals Experimental Approaches to Neutrino Nuclear Responses for ββ Decays and Astro-Neutrinos

2021 ◽  
Vol 9 ◽  
Author(s):  
Hiroyasu Ejiri
Keyword(s):  
Matrix Element ◽  
Charge Exchange ◽  
Nuclear Matrix ◽  
Experimental Studies ◽  
Nuclear Matrix Element ◽  
Exchange Reactions ◽  
Fundamental Properties ◽  
Experimental Approaches ◽  
Nuclear Responses ◽  
Beta Decays

Fundamental properties of neutrinos are investigated by studying double beta decays (ββ-decays), while atro-neutrino nucleo-syntheses and astro-neutrino productions are investigated by studying inverse beta decays (inverse β-decays) induced by astro-neutrinos. Neutrino nuclear responses for these ββ and β-decays are crucial for these neutrino studies in nuclei. This reports briefly perspectives on experimental studies of neutrino nuclear responses (square of nuclear matrix element) for ββ-decays and astro-neutrinos by using nuclear and leptonic (muon) charge-exchange reactions

scholarly journals Neutrino-Mass Sensitivity and Nuclear Matrix Element for Neutrinoless Double Beta Decay

Universe ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. 225
Author(s):  
Hiroyasu Ejiri
Keyword(s):  
Matrix Element ◽  
Beta Decay ◽  
Neutrino Mass ◽  
Nuclear Matrix ◽  
Experimental Studies ◽  
Neutrinoless Double Beta Decay ◽  
Nuclear Matrix Element ◽  
Double Beta Decay ◽  
Theoretical Evaluation ◽  
Mass Sensitivity

Neutrinoless double beta decay (DBD) is a useful probe to study neutrino properties such as the Majorana nature, the absolute neutrino mass, the CP phase and the others, which are beyond the standard model. The nuclear matrix element (NME) for DBD is crucial to extract the neutrino properties from the experimental transition rate. The neutrino-mass sensitivity, i.e., the minimum neutrino-mass to be measured by the DBD experiment, is very sensitive to the DBD NME. Actually, the NME is one of the key elements for designing the DBD experiment. Theoretical evaluation for the DBD NME, however, is very hard. Recently experimental studies of charge-exchange nuclear and leptonic reactions have shown to be used to get single-β NMEs associated with the DBD NME. Critical discussions are made on the neutrino-mass sensitivity and the NME for the DBD neutrino-mass study and on the experimental studies of the single-β NMEs and nuclear structures associated with DBD NMEs.

scholarly journals Nuclear Response to Second-Order Isospin Probes in Connection to Double Beta Decay

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 217
Author(s):  
Francesco Cappuzzello ◽  
Manuela Cavallaro
Keyword(s):  
Charge Exchange ◽  
Theoretical Calculations ◽  
Nuclear Matrix Element ◽  
Quantitative Information ◽  
Mass Scale ◽  
Second Order ◽  
Double Beta Decay ◽  
Coupling Constants ◽  
Exchange Reactions ◽  
Double Charge

One of the key ingredients needed to extract quantitative information on neutrino absolute mass scale from the possible measurement of the neutrinoless double-beta (0νββ) decay half-lives is the nuclear matrix element (NME) characterizing such transitions. NMEs are not physical observables and can only be deduced by theoretical calculations. However, since the atomic nuclei involved in the decay are many-body systems, only approximated values are available to date. In addition, the value of the coupling constants to be used for the weak interaction vertices is still an open question, which introduces a further indetermination in the calculations of NMEs. Several experimental approaches were developed in the years with the aim of providing useful information to further constrain the theory. Here we give an overview of the role of charge exchange reactions in this scenario, focusing on second-order processes, namely the double charge exchange (DCE) reactions.

scholarly journals Magnetic HexadecapoleγTransitions and Neutrino-Nuclear Responses in Medium-Heavy Nuclei

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Lotta Jokiniemi ◽  
Jouni Suhonen ◽  
Hiroyasu Ejiri
Keyword(s):  
Nuclear Matrix ◽  
Wave Functions ◽  
Matrix Elements ◽  
Heavy Nuclei ◽  
Magnetic Quadrupole ◽  
Order Of Magnitude ◽  
Nuclear Responses ◽  
Beta Decays ◽  
Gamow Teller ◽  
Phonon Model

Neutrino-nuclear responses in the form of squares of nuclear matrix elements, NMEs, are crucial for studies of neutrino-induced processes in nuclei. In this work we investigate magnetic hexadecapole (M4) NMEs in medium-heavy nuclei. The experimentally derived NMEs,MEXP(M4), deduced from observed M4γtransition half-lives are compared with the single-quasiparticle (QP) NMEs,MQP(M4), and the microscopic quasiparticle-phonon model (MQPM) NMEsMMQPM(M4). The experimentally derived M4 NMEs are found to be reduced by a coefficientk≈0.29with respect toMQP(M4) and byk≈0.33with respect toMMQPM(M4). The M4 NMEs are reduced a little by the quasiparticle-phonon correlations of the MQPM wave functions but mainly by other nucleonic and nonnucleonic correlations which are not explicitly included in the MQPM. The found reduction rates are of the same order of magnitude as those for magnetic quadrupoleγtransitions and Gamow-Teller (GT) and spin-dipole (SD)βtransitions. The impacts of the found reduction coefficients on the magnitudes of the NMEs involved in astroneutrino interactions and neutrinoless double beta decays are discussed.

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