Neutrino Nuclear Responses Research Articles

Ordinary Muon Capture for Double Beta Decay and Anti-Neutrino Nuclear Responses

This is a brief review on ordinary muon capture (OMC) experiments at Research Center for Nuclear Physics (RCNP) Osaka University relevant for the study of double beta decays (DBDs) and astro anti-neutrinos (neutrino) nuclear responses. OMC usually leaves the nucleus in highly excited unbound state. OMC is a charge exchange reaction via the charged weak boson as given by (μ,vμ) reactions with μ and vμ being the muon and muon neutrino. Subjects discussed include 1) unique features of OMC for studying DBDs and astro anti-neutrino (neutrino) nuclear responses, 2) experiments of OMCs on 100Mo and natMo to study neutrino nuclear responses for DBDs and astro anti-neutrinos, 3) impact of the OMC results on neutrino nuclear responses for DBDs and astro anti-neutrinos. Remarks and perspectives on OMC experiments for neutrino nuclear responses are briefly described.

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

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

Axial-vector weak coupling at medium momentum for astro neutrinos and double beta decays

Neutrino nuclear responses associated with medium momentum transfer of q = 20–80 MeV/c for astro neutrinos and double beta decays (DBDs) were studied by using charge exchange (3He, t) reactions on 128Te and 130Te. Gamow–Teller and spin-dipole nuclear matrix elements (NMEs) are found to be reduced uniformly in the wide momentum region of q = 20–80 MeV/c with respect to pnQRPA NMEs by the coefficient of kNM ≈ 0.35, while the Fermi NME for the isobaric analog state is given by the sum rule limit in the momentum transfer region. The reduction is discussed in terms of the quenching of the axial vector coupling gAeff for astro-neutrinos and DBDs.

Experimental studies of neutrino nuclear responses and nuclear structures for neutrino nuclear physics

Neutrino nuclear responses associated with astro neutrinos and double beta decays are crucial to extract neutrino properties of astro particle physics interests. The present report reviews briefly recent experimental studies of the neutrino nuclear responses. Single beta decays and electron captures, charge exchange nuclear reactions, muon and photon nuclear reactions, neutrino nuclear reactions and nucleon transfer reactions are used to study neutrino nuclear responses. Discussions are made on nucleonic and nonnucleonic spin isospin correlations and renormalization (quenching) effects on axial weak responses.

Statistical Neutron Emission Model for Neutrino Nuclear Response

The studies of neutrino fundamental properties are widely investigated by double beta decay and inverse beta decay. Recent muon capture experiment provides promising ways to directly evaluate the neutrino nuclear responses. This study provides theoretical explanation for neutrino nuclear responses by muon capture experiment. The effects of muon binding energy towards nuclear excitation region and pre-equilibrium (PEQ) and equilibrium (EQ) neutron decay mode will be discussed. The interpretation of muon strength model by comparison of calculator output and recent experimental data may provide relevant information towards determination of nuclear matrix element (NME) and its missing parameter.

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

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.

MOON for symmetry studies of neutrinos by double beta decays and neutrino nuclear responses

Neutrino-less double beta decays ( 0 ν β β ) are used for high sensitivity studies of symmetry properties of neutrinos such as the Majorana nature of neutrinos, the absolute mass scale, the CP at the lepton sector, and others. Neutrino nuclear responses ( 0 ν β β nuclear matrix elements) are crucial for extracting these neutrino properties from 0 ν β β experiments. This is a brief report of the present status of MOON (spectroscopic 0 ν β β experiment) with the ν-mass sensitivity of 100-30 meV, and experimental ways to study the neutrino nuclear responses.

Double beta decays and neutrino nuclear responses

Neutrino-less double beta decays ( 0 ν β β ), which violate the lepton number conservation law by Δ L = 2 , are unique and realistic probes for studying the Majorana nature of neutrinos, the ν mass spectrum and the absolute mass scale, the lepton sector CP and others beyond the standard electro-weak theory. Neutrino nuclear responses (nuclear matrix elements M 0 ν ) are crucial to extract neutrino properties of the particle physics interests from experimental 0 ν β β rates. Subjects discussed include 0 ν β β processes and Majorana neutrinos, the present and future 0 ν β β experiments, and neutrino nuclear responses ( M 0 ν ) and charge exchange reactions.

Spin isospin giant resonances and neutrino nuclear responses

Recent studies on nuclear spin isospin giant resonances and nuclear spin isospin responses for neutrinos are briefly summarized. Subjects discussed include i) experimental probes for nuclear spin isospin modes, ii) microscopic structures of spin isospin giant resonances, iii) spin isospin strengths and isobars, and iv) nuclear spin isospin responses for solar-ν and ββ - ν.

Neutrino nuclear responses and neutrino masses in inverse beta and double beta decays

Brief discussions are presented on neutrino (ν) nuclear responses and ν masses studied in nuclear microlaboratories. Subjects discussed include solar-ν nuclear responses in inverse β decays, ν masses and ββ - ν nuclear responses in ββ decays, and weakly interacting dark matters (DM) in nuclear elastic and inelastic scatterings.

Neutrinos and nuclear responses in nuclear double-β and inverse-β processes

Neutrino studies in nuclear microlaboratories and relevant neutrino nuclear responses are briefly discussed. Subjects discussed include i)neutrino nuclear physics in nuclear microlaboratories, ii)neutrino masses and weak interactions studied by nuclear double β decays, and iii)nuclear neutrino responses and charge exchange nuclear reactions.