Fundamental Neutron Physics: a White Paper on Progress and Prospects in the US

Abstract

Fundamental neutron physics, combining precision measurements and theory, probes particle physics at short range with reach well beyond the highest energies probed by the LHC. Significant US efforts are underway that will probe BSM CP violation with orders of magnitude more sensitivity, provide new data on the Cabibbo anomaly, more precisely measure the neutron lifetime and decay, and explore hadronic parity violation. World-leading results from the US Fundamental Neutron Physics community since the last Long Range Plan, include the world's most precise measurement of the neutron lifetime from UCN$\tau$, the final results on the beta-asymmetry from UCNA and new results on hadronic parity violation from the NPDGamma and n-${}^3$He runs at the FNPB (Fundamental Neutron Physics Beamline), precision measurement of the radiative neutron decay mode and n-${}^4$He at NIST. US leadership and discovery potential are ensured by the development of new high-impact experiments including BL3, Nab, LANL nEDM and nEDM@SNS. On the theory side, the last few years have seen results for the neutron EDM from the QCD $\theta$ term, a factor of two reduction in the uncertainty for inner radiative corrections in beta-decay which impacts CKM unitarity, and progress on {\it ab initio} calculations of nuclear structure for medium-mass and heavy nuclei which can eventually improve the connection between nuclear and nucleon EDMs. In order to maintain this exciting program and capitalize on past investments while also pursuing new ideas and building US leadership in new areas, the Fundamental Neutron Physics community has identified a number of priorities and opportunities for our sub-field covering the time-frame of the last Long Range Plan (LRP) under development. This white paper elaborates on these priorities.

arXiv admin note: text overlap with arXiv:2304.03451

References in corpus (35)

• An Improved Experimental Limit on the Electric Dipole Moment of the Neutron
• Measurement of the permanent electric dipole moment of the neutron
• Spin-Dependent Macroscopic Forces from New Particle Exchange
• Using Molecules to Measure Nuclear Spin-Dependent Parity Violation
• Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam
• Gravity Resonance Spectroscopy Constrains Dark Energy and Dark Matter Scenarios
• Single electron detection and spectroscopy via relativistic cyclotron radiation
• A New Constraint for the Coupling of Axion-like particles to Matter via Ultra-Cold Neutron Gravitational Experiments
• Anomaly mediated neutrino-photon interactions at finite baryon density
• More about neutron - mirror neutron oscillation
• Acoustic Rabi oscillations between gravitational quantum states and impact on symmetron dark energy
• Experiments in Fundamental Neutron Physics
• Extraction of the neutron charge radius from a precision calculation of the deuteron structure radius
• Limits on the Axial Coupling Constant of New Light Bosons
• Standard Model Gauging of the WZW Term: Anomalies, Global Currents and pseudo-Chern-Simons Interactions
• The parity-violating nucleon-nucleon force in the 1/N_c expansion
• Dispersion relation analysis of the radiative corrections to $g_A$ in the neutron $\beta$-decay
• Tests of Fundamental Quantum Mechanics and Dark Interactions with Low Energy Neutrons -- Extended Version
• Measurement of the neutron charge radius and the role of its constituents
• A chiral effective field theory study of hadronic parity violation in few-nucleon systems
• New precision measurements of free neutron beta decay with cold neutrons
• Measurement of the neutron decay electron-antineutrino angular correlation by the aCORN experiment
• Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly
• Constraints on the Dark Matter Interpretation $n\to \chi +e^{+}{e}^{-}$ of the Neutron Decay Anomaly with the PERKEO II experiment
• Elastic scattering of twisted neutrons by nuclei
• First direct constraints on Fierz interference in free neutron $\beta$ decay
• Twisting Neutral Particles with Electric Fields
• A Precision Measurement of the Neutron Scattering Length of He-4 Using Neutron Interferometry
• Large $N_c$ Expansion and the Parity Violating $\pi ,N,\Delta$ Couplings
• Experimental Test of Tight State-Independent Preparation Uncertainty Relations for Qubits
• Testing Lepton Flavor Universality and CKM Unitarity with Rare Pion Decays in the PIONEER experiment
• Experimental Upper Bound and Theoretical Expectations for Parity-Violating Neutron Spin Rotation in 4He
• First observation of cyclotron radiation from MeV-scale ${\mathrm{e}}^{pm}$ following nuclear beta decay
• Strong scattering and parallel guiding of ultracold neutrons
• Experimental Realization of Neutron Helical Waves