On the sensitivity of the D parameter to new physics

Abstract

Measurements of angular correlations in nuclear beta decay are important tests of the Standard Model (SM). Among those, the so-called D correlation parameter occupies a particular place because it is odd under time reversal, and because the experimental sensitivity is at the $10^{-4}$ level, with plans of further improvement in the near future. Using effective field theory~(EFT) techniques, we reassess its potential to discover or constrain new physics beyond the SM. We provide a comprehensive classification of CP-violating EFT scenarios which generate a shift of the D parameter away from the SM prediction. We show that, in each scenario, a shift larger than $10^{-5}$ is in serious tension with the existing experimental data, where bounds coming from electric dipole moments and LHC observables play a decisive role. The tension can only be avoided by fine tuning of the parameters in the UV completion of the EFT. We illustrate this using examples of leptoquark UV completions. Finally, we comment on the possibility to probe CP-conserving new physics via the D parameter.

arXiv comment33 pages; V2: updated reference to HighPT

References in corpus (27)

• Electroweak Measurements in Electron-Positron Collisions at W-Boson-Pair Energies at LEP
• Physics of leptoquarks in precision experiments and at particle colliders
• Measurement of the permanent electric dipole moment of the neutron
• Two-component spinor techniques and Feynman rules for quantum field theory and supersymmetry
• Effective Field Theory of Nuclear Forces
• A percent-level determination of the nucleon axial coupling from Quantum Chromodynamics
• New physics searches in nuclear and neutron $\beta$ decay
• Renormalization-group evolution of new physics contributions to (semi)leptonic meson decays
• Operators up to Dimension Seven in Standard Model Effective Field Theory Extended with Sterile Neutrinos
• Isovector Charges of the Nucleon from 2+1+1-flavor Lattice QCD
• Right-handed charged currents in the era of the Large Hadron Collider
• Comprehensive analysis of beta decays within and beyond the Standard Model
• The phenomenology of electric dipole moments in models of scalar leptoquarks
• Muon $g-2$ and scalar leptoquark mixing
• Isospin breaking in the nucleon mass and the sensitivity of beta decays to new physics
• Effective field theory interpretation of lepton magnetic and electric dipole moments
• Global Constraints on Lepton-Quark Contact Interactions
• Operator Bases in Effective Field Theories with Sterile Neutrinos: $d\le 9$
• Combined Constraints on First Generation Leptoquarks
• First-Generation New Physics in Simplified Models: From Low-Energy Parity Violation to the LHC
• Semileptonic tau decays beyond the Standard Model
• D vs d: CP Violation in Beta Decay and Electric Dipole Moments
• Non-Perturbative Effects in $\mu \to e\gamma$
• The D coefficient in neutron beta decay in effective field theory
• Lattice QCD Determination of $g_A$
• Left-right symmetry and electric dipole moments. A global analysis
• Right-Handed Neutrinos and T-Violating, P-Conserving Interactions

Cited by in corpus (3)

• Particle Physics at the European Spallation Source
• The Standard Model theory of neutron beta decay
• Opportunities and open questions in modern $\beta$ decay