An electroweak basis for neutrinoless double β decay
Abstract
Here, a discovery of neutrinoless doubleβ decay would be profound, providing the first direct experimental evidence of ΔL = 2 lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At lowenergies such new physics could manifest itself in the form of color and SU(2) _{L} × U(1)Y invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension9 operators, and our analysis supersedes those that only impose U(1) _{em} invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing U(1) _{em} invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4quark operators using chiral perturbation theory, and apply it to determine which of these operators have longdistance pion enhancements at leading order in the chiral expansion. We also find at dimension11 and dimension13 the electroweak invariant operators that after electroweak symmetrymore »
 Authors:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Publication Date:
 Research Org.:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Sponsoring Org.:
 USDOE Laboratory Directed Research and Development (LDRD) Program
 OSTI Identifier:
 1398909
 Report Number(s):
 LAUR1623550
Journal ID: ISSN 10298479
 Grant/Contract Number:
 AC5206NA25396
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Journal of High Energy Physics (Online)
 Additional Journal Information:
 Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2017; Journal Issue: 8; Journal ID: ISSN 10298479
 Publisher:
 Springer Berlin
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Atomic and Nuclear Physics; Beyond Standard Model; Neutrino Physics; Chiral Lagrangians
Citation Formats
Graesser, Michael L. An electroweak basis for neutrinoless double β decay. United States: N. p., 2017.
Web. doi:10.1007/JHEP08(2017)099.
Graesser, Michael L. An electroweak basis for neutrinoless double β decay. United States. doi:10.1007/JHEP08(2017)099.
Graesser, Michael L. 2017.
"An electroweak basis for neutrinoless double β decay". United States.
doi:10.1007/JHEP08(2017)099. https://www.osti.gov/servlets/purl/1398909.
@article{osti_1398909,
title = {An electroweak basis for neutrinoless double β decay},
author = {Graesser, Michael L.},
abstractNote = {Here, a discovery of neutrinoless doubleβ decay would be profound, providing the first direct experimental evidence of ΔL = 2 lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At lowenergies such new physics could manifest itself in the form of color and SU(2)L × U(1)Y invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension9 operators, and our analysis supersedes those that only impose U(1)em invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing U(1)em invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4quark operators using chiral perturbation theory, and apply it to determine which of these operators have longdistance pion enhancements at leading order in the chiral expansion. We also find at dimension11 and dimension13 the electroweak invariant operators that after electroweak symmetry breaking produce the remaining ΔL = 2 operators that would appear at dimension9 if only U(1)em is imposed.},
doi = {10.1007/JHEP08(2017)099},
journal = {Journal of High Energy Physics (Online)},
number = 8,
volume = 2017,
place = {United States},
year = 2017,
month = 8
}
Web of Science

A twodelta (..delta delta..) process and a new twonucleon (NN) process are proposed for neutrinoless (0..nu..) ..beta beta.. decay. The conventional NN mechanism is also examined. The N..delta.. interaction and the integration over virtual neutrino momenta lead to the dominance of the ..delta delta.. process. This dominance enables one to relate 0..nu.. ..beta beta.. decay rates and forwardangle doublechargeexchange (DCE) cross sections for 0/sup +/(g.s.)..>..0/sup +/(g.s.) transitions, and to use this relation to obtain limits on leptonnumber nonconservation from experimental DCE cross sections in a nearly nuclearstructuremodelindependent way.

Limits on single and double Majoron emission processes in neutrinoless double [beta] decay of [sup 100]Mo
The single Majoron emission mode ([beta][beta][ital B]) and the double Majoron emission mode ([beta][beta][ital BB]) in the neutrinoless double [beta] decays of [sup 100]Mo were studied by using the ultralow background nuclear spectrometer ELEGANTS V. Lower limits on the halflives were deduced as [ital T][sub 1/2][sup [beta][beta][ital B]][gt]7.9[times]10[sup 20] yr and [ital T][sub 1/2][sup [beta][beta][ital B][ital B]][gt]5.3[times]10[sup 19] yr (68%) CL, respectively. They set the upper limit of [vert bar][l angle][ital g][sub [ital B]][r angle][vert bar][lt]2.0[times]10[sup [minus]4] on the Majoron coupling constant, and the lower limit of [ital M][sub [ital [tilde Z]]][gt]0.038 GeV on the Majorana mass of the [italmore » 
Piondoublechargeexchange contribution to neutrinoless double. beta. decay
It is shown that the double charge exchange of pions in flight between two nucleons makes a substantial contribution to neutrinoless nuclear double..beta.. decay if it is mediated by heavy Majorana neutrinos. 
Neutrinoless double. beta. decay and pion double charge exchange
A Comment on the Letter by A. Fazely and L. C. Liu, Phys. Rev. Lett. 57, 968 (1986). 
CP violation, tritium beta decay, and neutrinoless doublebeta decay
CPviolation effects in neutrinoless doublebeta decays are discussed in the case of twogeneration Majorana neutrinos. It is shown that the recent experimental results of /sup 3/H beta decay and neutrinoless doublebeta decay, when taken at their face values, imply that the CPviolating phase angle in the mixing matrix for the lefthanded lepton sector must be less than 16/sup 0/.