<p>Right-handed weak currents (RHCs) in the left-right symmetric model for neutrinoless double beta decays (DBDs) of both the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mn>0</mn><mo>+</mo></msup><mspace width="3.33333pt"></mspace><mo>→</mo><mspace width="3.33333pt"></mspace><msup><mn>0</mn><mo>+</mo></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mn>0</mn><mo>+</mo></msup><mspace width="3.33333pt"></mspace><mo>→</mo><mspace width="3.33333pt"></mspace><msup><mn>2</mn><mo>+</mo></msup></mrow></math> transitions are discussed from both theoretical and experimental viewpoints. <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>λ</mi><mo>〉</mo></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>η</mi><mo>〉</mo></mrow></math> terms are related by <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>λ</mi><mo>〉</mo><mo>/</mo><mo>〈</mo><mi>η</mi><mo>〉</mo><mo>≈</mo><mo form="prefix">tan</mo><mi>β</mi></mrow></math>, which is constrained in the regions of 1–60 for SUSY grand unified theories (GUTs) and of 1–165 for non-SUSY GUTs. The enhancement mechanisms of the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>η</mi><mo>〉</mo></mrow></math> term over the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>λ</mi><mo>〉</mo></mrow></math> term in the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mn>0</mn><mo>+</mo></msup></math> transition is shown, and the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Δ</mi></math> isobar contribution to the nuclear matrix element (NME) for the transition to the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mn>2</mn><mo>+</mo></msup></math> state is found to be of the order of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mn>20</mn><mo>%</mo></mrow></math> of the NME with the quenched weak coupling. The new and interesting RHC regions of <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>λ</mi><mo>〉</mo><mo>≈</mo><mn>5</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>8</mn></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mi>η</mi><mo>〉</mo><mo>≈</mo><mn>1.5</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>10</mn></mrow></msup></mrow></math> are shown to be exclusively explored by measuring both the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>β</mi><mi>β</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>γ</mi></math> rays associated with the ground and excited DBDs by means of the ton-scale DBD detectors for the inverted hierarchy <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>ν</mi></math> masses. The actual RHCs to be studied depend on the RHC NMEs.</p>

Japan

Hiroyasu Ejiri

Takeshi Fukuyama

Toru Sato

Right-handed weak currents in neutrinoless <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>β</mi><mi>β</mi></mrow></math> decays and ton-scale <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>β</mi><mi>β</mi></mrow></math> detectors

The possibility of detection of 5.5 MeV and 14.4 keV solar axions by observing axion-induced nuclear and atomic transitions is investigated. The presence of nuclear transitions between spin orbit partners can be manifested by the subsequent deexcitation via gamma ray emissions. The transition rates can also be studied in the context of radiative axion absorption by a nucleus. The elementary interaction is obtained in the context of the axion-quark couplings predicted by existing axion models. Then, these couplings will be transformed to the nucleon level utilizing reasonable existing models, which lead to effective transition operators. Using these operators, we calculate the needed nuclear matrix elements employing wave functions obtained in the context of the nuclear shell model. With these ingredients, we discuss possibilities of experimental observation of the axion-induced nuclear gamma rays. In the second part, we will examine the axion-induced production of X-rays (axion-photon conversion) or ionization from deeply bound electron orbits. In this case, the axion electron coupling is predicted by existing axion models; no renormalization is needed. The experimental signal is the observation of directly produced electrons and/or the emission of hard X-rays and Auger electrons, following the deexcitation of the final atom. Critical discussion is made on the experimental feasibility of detecting the solar axions by using multiton scale NaI detectors.

Greece

Paraskevi C. Divari

South Korea

John D. Vergados

Calculated Event Rates for Axion Detection via Atomic and Nuclear Processes

Theocharis Kosmas

United States

Athanasios Hatzikoutelis

Neutrino Physics in the Frontiers of Intensities and Very High Sensitivities 2018

Neutrino Physics in the Frontiers of Intensities and Very High Sensitivities 2016

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, <math id="M2"><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>E</mi><mi>X</mi><mi>P</mi></mrow></msub></mrow></math>(M4), deduced from observed M4 <math id="M3"><mrow><mi>γ</mi></mrow></math> transition half-lives are compared with the single-quasiparticle (QP) NMEs, <math id="M4"><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>Q</mi><mi>P</mi></mrow></msub></mrow></math>(M4), and the microscopic quasiparticle-phonon model (MQPM) NMEs <math id="M5"><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>M</mi><mi>Q</mi><mi>P</mi><mi>M</mi></mrow></msub></mrow></math>(M4). The experimentally derived M4 NMEs are found to be reduced by a coefficient <math id="M6"><mi>k</mi><mo>≈</mo><mn>0.29</mn></math> with respect to <math id="M7"><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>Q</mi><mi>P</mi></mrow></msub></mrow></math>(M4) and by <math id="M8"><mi>k</mi><mo>≈</mo><mn>0.33</mn></math> with respect to <math id="M9"><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>M</mi><mi>Q</mi><mi>P</mi><mi>M</mi></mrow></msub></mrow></math>(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 quadrupole <math id="M10"><mrow><mi>γ</mi></mrow></math> transitions and Gamow-Teller (GT) and spin-dipole (SD) <math id="M11"><mrow><mi>β</mi></mrow></math> transitions. The impacts of the found reduction coefficients on the magnitudes of the NMEs involved in astroneutrino interactions and neutrinoless double beta decays are discussed.

Finland

Jouni Suhonen

Lotta Jokiniemi

Magnetic Hexadecapole Transitions and Neutrino-Nuclear Responses in Medium-Heavy Nuclei