A new Quantum Field Theory (QFT) formalism for neutrino oscillations in a vacuum is proposed. The neutrino emission and detection are identified with the charged-current vertices of a single second-order Feynman diagram for the underlying process, enclosing neutrino propagation between these two points. The critical point of this approach is the definition of the space-time setup typical for...
Recently, sensitive experiments operating in frontier muon facilities like MuSEUM (J‐PARC), Mu-MASS (PSI), etc. provide ultra‐high‐precision measurements for quantum electrodynamics (QED) and non-standard (BSM) physics. Historically, the spectroscopy of conventional atoms played essential role in understanding physics (Lamb shift, bound state QED, etc.). However, the proton finite size...
In this talk we are presenting and discussing our results for some
Double Charge Exchange (DCX) systems. The calculations are performed for
light and heavy nuclei participant in the reactions. The microscopic structure
( wave functions and energy spectra) of the light nuclei is given in terms of
shell model results. For the heavy mass partners we use the Quasiparticle Ran-
dom Phase...
Among the potentially double-beta decay (DBD) active natural isotopes, $^{96}$Zr is promising because of its high energy transition ($Q_{2\beta}=3.35$ MeV) that helps to overcome issues with background events generated by environmental $\gamma$ radioactivity and internal $\beta$-active nuclides from U/Th decay chains. Moreover the $^{94}$Zr isotope has a lower Q$_{2\beta}$-value (1.14 MeV)...
The ordinary muon capture (OMC) is a process where a nucleus captures a negative muon from the lowest atomic orbital, the 1s orbital, and modern muon facilities in Japan and Switzerland can produce these muons and shoot them at target atoms. The mass of the captured muon is some 100 MeV, thus introducing momentum exchanges in the range of 100 MeV, in the ballpark of the momentum exchanges...
Ordinary muon capture is a nuclear-weak process in which a negatively charged muon, initially bound on an atomic orbit, is captured by the atomic nucleus, resulting in atomic number reduction by one and emission of a muon neutrino. Thanks to the high momentum transfer involved in the process, it is one of the most promising probes for as yet hypothetical neutrinoless double-beta decay. With...
TBA
We investigate the atomic exchange effect between the final atom's bound electrons and those emitted in the allowed $\beta$ decay and $2\nu\beta\beta$ decay of the initial nucleus. The electron wave functions are obtained with the Dirac-Hartree-Fock-Slater self-consistent method, and we ensure the orthogonality between the continuum and bound electron states of the final atom by modifying the...
Double-beta decay of nuclei, especially neutrinoless double-beta decay, is one of the most intriguing topics in nuclear physics. Observing the neutrinoless double-beta decay would mean physics beyond the standard model. In this presentation, I will cover some of the results of the studies of giant resonances in double-beta decay nuclei and the corresponding daughter nuclei. The strength...
Predictions of neutrinoless double-beta decay (0nbb) nuclear matrix elements are challenging, and markedly differ from each other when different many-body methods are used. One possible avenue to improve this current status is to use data from other observables related to 0nbb to test the theoretical calculations, and to use correlations of these observables with 0nbb matrix elements to...
A solid observation of neutrino-less double beta decay (0νDBD) relies on the possibility of operating high-energy resolution detectors with detailed background control. Scintillating cryogenic calorimeters are one of the most promising tools to fulfill the requirements for a next-generation experiment. CUPID-0 has been the first demonstrator of the proposed CUPID experiment based on this...
The MAJORANA DEMONSTRATOR recently concluded its search for neutrinoless double-beta decay. The experiment operated an array of up to 40.4 kg of germanium detectors, 27 kg of which were isotopically enriched in $^{76}$Ge and housed inside a compact shield consisting of lead and copper at the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment achieved a world leading...
We describe the MONUMENT project (Muon Ordinary capture for NUclear Matrix elemENTs calculations) aims to determine ordinary muon capture (OMC) rates, which could help in studying nuclear responses for antineutrinos associated with double beta decays (ββ) and astroneutrino interactions.
The MONUMENT project has conducted a series of meticulous measurements at the PSI muon facility in...
Calculation of the nuclear matrix elements (NMEs) for double-beta decay is of paramount importance for guiding experiments and for analyzing and interpreting the experimental data, especially for the search of the neutrinoless double beta decay mode (0νββ). However, there are currently still large differences between the NME values calculated by different methods, hence a quantification of...
A qualitative difference in the running sum to the nuclear matrix element of the two-neutrino double-$\beta$ decay of $^{136}$Xe has been found four years ago between QRPA and shell model calculations. The former result has large increase and decrease with respect to the excitation energy of the intermediate state, and the latter one is an almost monotonically and mildly increasing function....
The new particle physics underlying any potential lepton-number-violating signal of neutrinoless double beta decay can be parametrized within the framework of effective field theory in terms of a set of higher-dimensional operators triggering a variety of distinct mechanisms. While it seems to be challenging to unravel the dominant contribution from the observation of this rare nuclear process...
Theoretical research is conducted for interesting isotopes using nuclear shell model to predict level schemes, half-lives, and beta spectral shapes. Further studies of these aspects for isotopes of interest shine a light on different phenomena of such as reactor anti-neutrino anomaly in 92Rb, background effects of beta decays such as 214Pb in Dark Matter experiments, and helping Neutrino's...
Coherent elastic neutrino-nucleus scattering (CEνNS) is a weak neutral current process where the neutrino interacts coherently with the nucleus as a whole. It that has been demonstrated to be a powerful tool to investigate nuclear and electroweak physics since its first observation in 2017 at COHERENT exploiting a CsI detector.
In this presentation, I will present the state-of-the-art results...
Neutrinoless double-beta decay (0$\nu\beta\beta$) is a key process to address some of the major outstanding issues in particle physics, such as the lepton number conservation and the Majorana nature of the neutrino. Several efforts have taken place in the last decades in order to reach higher and higher sensitivity on its half-life. The next-generation of experiments aims at covering the...
In this presentation, we will report two new studies on the spectral shape: the $2\nu\beta\beta$ decay of the $^{100}$Mo in the CUPID-Mo experiment, and the $^{113}$Cd $\beta$ decay in the framework of the CROSS project. The CUPID-Mo experiment is a demonstrator for the next generation 0νββ experiment CUPID.
The experiment is an array of 20 enriched Li$_2$$^{100}$MoO$_4$ bolometers and 20 Ge...
An experiment to study double beta decay processes in $^{106}$Cd using a $^{106}$CdWO$_4$ crystal scintillator (mass 215 g) enriched in $^{106}$Cd at 66$\%$ is in progress at the Laboratori Nazionali del Gran Sasso (LNGS), in Italy. Events in the $^{106}$CdWO$_4$ detector are recorded in (anti)coincidences with two large-volume CdWO$_4$ scintillation counters. The design of the detector...
Experimental studies of nuclear matrix elements for double beta decays are crucial since theoretically evaluated NMEs are very sensitive to the nuclear models and the nuclear parameters used for the calculations. Single and double charge exchange reactions have been used to study experimentally the GT NMEs associated with DBD NMEs. We show in the present work that M1 and E1 gamma transitions...
A question of high interest is how to relate double charge exchange (DCE) reactions and double beta decay [1-3]. DCE reaction theory predicts two interfering reaction mechanisms, namely second order Double Single Charge Exchange (DSCE) and first order Meson-Nucleon Majorana DCE (MDCE).
The DSCE mechanism is a distorted wave (DW) two-step reaction wher a reaction amplitude is related to the...
The structureless purely leptonic atoms are ideal for testing quantum electrodynamics (QED) and beyond the Standard Model theories (BSM). In recent years, Muonium (Mu) and Positronium (Ps) are considered prominent examples of leptonic atoms that are thoroughly being investigated towards the above aim. A non-relativistic description of leptonic systems provides a simplified quantum mechanical...
In this work, we first formulate the reduced radial Schrödinger equation for a two-leptons system by separating out the center of mass motion. Then, a neural networks technique is, initially, employed to model the numerical solution of the Schrödinger equation written in terms of the relative coordinate r of the two leptons. Next, for the optimization of the defined error function of the...
We offer a comprehensive investigation of electron capture ratios, spanning a wide range of atomic numbers. Our study utilizes a self-consistent computational method that accounts for essential factors such as electron screening, electron correlations, overlap, and exchange corrections, alongside shake-up and shake-off atomic effects.
To compute the electronic wave functions, we employ the...
The AMoRE (Advanced Mo-based Rare process Experiment) aims to study the double beta decay of 100Mo in order to gain insights into neutrino masses using a cryogenic technique. The study of 2vββ decay from 100Mo to an excited state of 100Ru helps us understand nuclear matrix elements and nuclear models as well as search for the bosonic (symmetric) fraction of the neutrino wave function.
The...
BINGO is a prototype experiment to demonstrate a path towards a nearly background free tonne-scale cryogenic $0\nu\beta\beta$ experiment with O(10000) detectors with the isotopes $^{100}$Mo and $^{130}$Te. The major design aspects to achieve this goal are (1) a novel detector assembly reducing the exposed surface area of un-instrumented (passive) materials in the detector array by more than...
The ACCESS (Array of Cryogenic Calorimeters to Evaluate Spectral Shapes) project aims to establish a novel detector to perform a precise study of the spectral shape of forbidden β-decays. These strongly suppressed processes can help to clarify the long-standing issue of the axial coupling constant (gA) quenching. Moreover, such rare decays are also a common source of systematic uncertainty in...
The spectrum-shape method has been proposed to determine the effective value of weak coupling constants g$_V$ (vector part) and g$_A$ (axial-vector part) in forbidden β decays. The nuclear transition from $^{99}$Tc(9/2$^+$) to $^{99}$Ru(5/2 $^+$) is 2$\rm^{nd}$ non-unique forbidden β decay, the shape function strongly depends on the g$_A$ of variant nuclear-model frameworks. The maximum...
The nuclear matrix element for neutrinoless double beta decay of $^{76}$Ge can be expressed as a sum over all transitions along states of the intermediate nucleus $^{76}$As. The dominant contribution is expected to be the ground state of $^{76}$As. Experimentally the contribution of the $^{76}$As ground state can be investigated via the branching ratios of its $\beta^-$ and electron capture...
TBA
We present νDoBe, a Python tool for the computation of neutrinoless double beta decay (0νββ) rates in terms of lepton-number-violating operators in the Standard Model Effective Field Theory (SMEFT). The tool can be used for automated calculations of 0νββ rates, electron spectra and angular correlations for all isotopes of experimental interest, for lepton-number-violating operators up to and...
