nucl-th digest · Apr 13, 2023

ν

DoBe -- A Python Tool for Neutrinoless Double Beta Decay

We present

ν

DoBe, a Python tool for the computation of neutrinoless double beta decay (

0 ν β β

) 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

0 ν β β

rates, electron spectra and angular correlations for all isotopes of experimental interest, for lepton-number-violating operators up to and including dimension 9. The tool takes care of renormalization-group running to lower energies and provides the matching to the low-energy effective field theory and, at lower scales, to a chiral effective field theory description of

0 ν β β

rates. The user can specify different sets of nuclear matrix elements from various many-body methods and hadronic low-energy constants. The tool can be used to quickly generate analytical and numerical expressions for

0 ν β β

rates and to generate a large variety of plots. In this work, we provide examples of possible use along with a detailed code documentation. The code can be accessed through: GitHub: https://github.com/OScholer/nudobe Online User-Interface: https://nudobe.streamlit.app

↳ hep-phhep-exnucl-exnucl-thJHEP(2023)·30 citations

Integrating by parts at finite density

Juuso Österman🇫🇮 · Philipp Schicho🇫🇮 · Aleksi Vuorinen🇫🇮

Both nonzero temperature and chemical potentials break the Lorentz symmetry present in vacuum quantum field theory by singling out the rest frame of the heat bath. This leads to complications in the application of thermal perturbation theory, including the appearance of novel infrared divergences in loop integrals and an apparent absence of four-dimensional integration-by-parts (IBP) identities, vital for high-order computations. Here, we propose a new strategy that enables the use of IBP techniques in the evaluation of Feynman integrals, in particular vacuum or bubble diagrams, in the limit of vanishing temperature $T$ but nonzero chemical potentials $μ$ . The central elements of the new setup include a contour representation for the temporal momentum integral, the use of a small but nonzero $T$ as an IR regulator, and the systematic application of both temporal and spatial differential operators in the generation of linear relations among the loop integrals of interest. The relations we derive contain novel inhomogeneous terms featuring differentiated Fermi-Dirac distribution functions, which severely complicate calculations at nonzero temperature, but are shown to reduce to solvable lower-dimensional objects as $T$ tends to zero. Pedagogical example computations are kept at the one- and two-loop levels, but the application of the new method to higher-order calculations is discussed in some detail.

↳ hep-phhep-thnucl-thJHEP(2023)·9 citations

Thursday·April 13, 2023

$ν$ DoBe -- A Python Tool for Neutrinoless Double Beta Decay

Integrating by parts at finite density

Affiliations

νDoBe -- A Python Tool for Neutrinoless Double Beta Decay

Integrating by parts at finite density

Affiliations

$ν$ DoBe -- A Python Tool for Neutrinoless Double Beta Decay