Centre International de Formation et de Recherche Avancées en Physique

Contributions to the study of double-beta decay and investigation of physics beyond the Standard Model

Cod proiect PN-III-P4-ID-PCE-2020-2374
Nr contractului PCE 99
Titlul proiectului
(în română)
Contributii la studiul dezintegrarii beta duble si investigarea fizicii dincolo de Modelul Standard
Titlul proiectului
(în engleză)
Contributions to the study of double-beta decay and investigation of physics beyond the Standard Model
Acronimul proiectului DBD-BSM
Propunerea de proiect în engleză*

(fișier tip .PDF)

Cererea_de_finantare_PCE_2020 – Sectiunile B si C_DEPUS.pdf
(15/06/2020, 569.1 kb)
Domeniu PE2_3 – Nuclear physics

PE2_1 – Fundamental interactions and fields

Abstract
(în română)
Dezintegrarea beta dubla (DBD) reprezinta cel mai lung process de dezintegrare nucleara spontana care a fost observat experimental, cu timpi de viata de ordinul 10^20 ani. Acest proces are un mare potential de descoperire, in principal datorita posibilitatii ca dezintegrarea sa aiba loc si fara emisie de neutrini, incalcandu-se astfel legea conservarii numarului leptonic. Descoperirea acestui mod de dezintegrare ne-ar putea furniza informatii cheie despre: i) proprietati fundamentale ale neutrinilor, inca nestiute (daca este particla Dirac sau Majorana?, si indicii asupra valorii masei lor absolute, ierarhia maselor existenta si altor specii de neutrini (sterili), etc.); ii) mecanismele care pot contribui la producerea acetui mod de dezintegrare (cum ar fi: schimbul de neutrini usori sau gri, schimbul de particule supersimetrice-SUSY, cu emisie a unui Majoron, cu contributii de la componente RH din interactia slaba, etc.); iii) valididatea unor legi de conservare (conservarea numarului leptonic, a simetriei CP sau a simetriei Lorentz). Toate aceste probleme sunt legate de existenta unor fenomene ce nu pot fi explicate in cadrul Modelului Standard (MS). In acest proiect ne propunem sa aducem contributii semnificative la studiul procesului de dezintegrare beta duble aducand progrese in toate cele trei “parti” ce compun expresiile timpilor de viata: calculul factorilor spatiu de faza, calculul elementelor de matrice nucleare si investigarea unor fenomene dincolo de MS.
Abstract
(în engleză)
Double-beta decay (DBD) is the rarest spontaneous nuclear decay process experimentally observed until now with half-lives of the order of 10^20 years. It has a broad potential of discovery mainly due to the search of the decay mode without emission of neutrinos 0νββ decay. Its discovery would provide us with key information about i) neutrino properties (neutrino character: Dirac or Majorana particle and hints about its absolute mass, mass hierarchy, neutrino flavors, existence of sterile neutrinos, etc.), ii) mechanisms which can contribute to 0νββ (such as: exchange of light/heavy neutrinos, exchange of SUSY particles, Majoron emission, contribution from RH currents from the weak interaction, etc.) and iii) on the validity of some conservation laws (lepton number, CP violation, Lorentz invariance, etc.). All these issues are related to physics beyond the SM. In this project we aim to bring significant contributions in the DBD study by doing advances in all parts of the DBD half-lives: the calculation of the phase space factors and nuclear matrix elements, and investigation of beyond SM phenomena as constraints of LNV parameters, Lorentz invariance violation in the neutrino sector, and other related issues.
Obiectivul proiectului
(în română)
Obiectivul general al proiectului este obtinerea unor rezultate semnificative in studiul procesului de dezintegrare beta dubla, ce vizeaza calculul factorilor spatiu de faza, calculul elementelor de matrice nucleare si investigarea unor fenomene dincolo de Modelul Standard.
Obiectivul proiectului
(în engleză)
The general objective of the project is to obtain significant results in the study of double beta decay process, aimed at calculating phase space factors, nuclear matrix elements and investigating phenomena beyond the Standard Model.e) investigating parameters and phenomena beyond the SM:
Rezultatele estimate
(în română)
a)imbunatatirea codurilor de calcul a PSF prin obtinerea unei stabilitati mai bune fata de instabilitatile numerice ce pot apare in apropierea valorilor energiei electronilor apropiate de zero si imbunatatirea functiilor de unda electronice utilizate in constructia functiilor Fermi necesare in calcul;
b)  imbunatatirea codului nostru actual bazat pe ShM, de calcul al NME pentru a calcula simultan toate NME pentr modul de dezintegrare 0νββ asociate cu diferite mecanisme LNV si cu utilizarea consistenta a parametrilor de input;
c) efectuarea de noi calcule extinse ale spectrelor electronice, singulare, de energie insumata si de corelatii unghiulare intre electroni;
d) efectuarea de calcule ale celor mai noi contributii la NME ce intra in timpii de viata ai DBD, propuse in literatura, testarea stabilitatii calculelor la parametrul de quenching care afecteaza semnificativ calculul NME, reducerea incertitudinilor legate de constanta axial-vectoare g_A prin utilizarea rapoartelor de g_A pentru diferiti izotopi isotopes, in locul valorilor lor absolute, obtinerea de limite stringente ale parametrilor LNV parameters din experimente DBD;
e) constrangerea parametrilor BSM si obtinerea de informatii despre unele fenomene BSM: i) constrangerea parametrilor legati de masa neutrinilor ii) furnizarea experimentatorilor ce studiaza DBD a unor spectre energetice teoretice ale electronilor, distributii unghiulare, etc. folosite in studiul violarii invariantei Lorentz (LIV) in dezintegrarea beta dubla;
f) implementarea unor noi versiuni, imbunatatite, de metode teoretice de studiu al DBD;
g) diseminarea rezultatelor obtinute in cadrul proiectului in conferinte, workshop-uri si  scoli de fizica.
Rezultatele estimate
(în engleză)
a)improving our present PSF codes by getting more robustness against the instability that may appear at zero kinetic energy of electrons and improving the radial electron used in building the Fermi functions needed in calculation;
b) improving our present ShM code to perform simultaneously all the desired 0νββ NME, associated with various LNV mechanisms and using consistently the input parameters in all parts of the computations;
c) performing new extended calculations of the summed energy spectra of electrons, single and differential electron spectra and of angular correlations between electrons.
d) performing calculation of the newest NME contributions to DBD half-lives proposed in literature in literature, test the stability of the quenching factor that affects the NME calculations, reducing the uncertainties related to the axial-vector constant g_A, by using ratios of g_A values of different isotopes, instead their absolute values, obtaining of stringent limits of the LNV parameters from the most advanced experiments and, using our PSF and NME calculations;
e) investigating parameters and phenomena beyond the SM: i) constraining of neutrino mass parameters, ii) providing experimenters with accurate single and summed energy
electron spectra and angular correlations to be used in the study of LIV in double-beta decay;
f) implementation of new versions of theoretical methods to study the DBD process;
g) dissemination of the results in conferences, workshops and schools

 

Team:                                                               Prof. Sabin Stoica, senior researcher 1 – director

Dr. Andrei Neacsu, senior researcher 3

Drd. Ovidiu Vasile Nitescu

Drd. Stefan Alexandru Ghinescu

Vasile Alin Sevestrean, master student

 

Results:      

Articles

Angular Distributions of Emitted Electrons in the Two-Neutrino ββ Decay, O Niţescu, R Dvornický, S Stoica, F Šimkovic – Universe, 7, 147 (2021)

– Brief Review of the Results Regarding the Possible Underlying Mechanisms Driving the Neutrinoless Double Beta Decay, A. Neacsu, V.A. Sevestrean and S. Stoica, Front. Phys., 21 May 2021 | https://doi.org/10.3389/fphy.2021.666591

 

 



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