Measurement of the Proton Asymmetry Parameter in Neutron Beta Decay

Schümann, M.; Kreuz, Michael; Deissenroth, M.; Glück, F.; Krempel, J.; Märkisch, Bastian; Mund, D.; Petoukhov, A.; Söldner, T.; Abele, H.

doi:10.1103/physrevlett.100.151801

Cited by 51 publications

(34 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The analytical expressions for the NLO corrections can be found in Eqs. (50)(51)(52)(53)(54)(55)(56)(57) and Eqs. (62-63) and have been evaluated with the form factor values listed in Eqs.…”

Section: Numerical Resultsmentioning

confidence: 99%

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

2019

View full text Add to dashboard Cite

We elaborate on the dichotomy between the description of the semileptonic decays of heavy hadrons on the one hand and the semileptonic decays of light hadrons such as neutron β decays on the other hand. For example, almost without exception the semileptonic decays of heavy baryons are described in cascade fashion as a sequence of two two-body decays B1 → B2 + W off−shell and W off−shell → ℓ+ν ℓ whereas neutron β decays are analyzed as true three-body decays n → p+e − +νe. Within the cascade approach it is possible to define a set of seven angular observables for polarized neutron β decays as well as the longitudinal, transverse and normal polarization of the decay electron. We determine the dependence of the observables on the usual vector and axial vector form factors. In order to be able to assess the importance of recoil corrections we expand the rate and the q 2 averages of the observables up to NLO and NNLO in the recoil parameter δ = (Mn − Mp)/(Mn + Mp) = 0.689 · 10 −3 . Remarkably, we find that the rate and three of the four parity conserving polarization observables that we analyze are protected from NLO recoil corrections when the second class current contributions are set to zero.

show abstract

Section: Numerical Resultsmentioning

confidence: 99%

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

2019

View full text Add to dashboard Cite

show abstract

“…For these experiments, the use of a series of opaque spin filters (see Sec. VII.E.1) has been employed to determine neutron polarization to 0.1 % accuracy, thus substantially reducing this contribution to the overall uncertainty budget (Mund et al , 2013; Schumann et al , 2008, 2007). An NSF was also used to determine the neutron polarization in a measurement of the neutron electric dipole moment via spin rotation in a non-centrosymmetric crystal (Fedorov et al , 2010).…”

Section: Neutron Spin-filtersmentioning

confidence: 99%

Optically polarizedHe3

et al. 2017

View full text Add to dashboard Cite

This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

show abstract

“…However, the uncertainty in B is considerably higher than with the previous method. The analysis in [91] relies partly 400 600 Figure 18. Asymmetry with respect to the direction of the neutron spin for the count rate of events in which both decay electron and proton are detected by detector 2 in the PERKEO II experiment [90] as a function of the electron kinetic energy.…”

Section: The Neutrino Asymmetry B In Neutron Beta Decaymentioning

confidence: 99%

New precision measurements of free neutron beta decay with cold neutrons

Baeßler

Bowman

Penttilä

et al. 2014

J. Phys. G: Nucl. Part. Phys.

View full text Add to dashboard Cite

Abstract. Precision measurements in free neutron beta decay serve to determine the coupling constants of beta decay, and offer several stringent tests of the Standard Model. This paper describes the free neutron beta decay program planned for the Fundamental Physics Beamline at the Spallation Neutron Source at Oak Ridge National Laboratory, and puts it into the context of other recent and planned measurements of neutron beta decay observables.

show abstract

Measurement of the Proton Asymmetry Parameter in Neutron Beta Decay

Cited by 51 publications

References 13 publications

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

Optically polarizedHe3

New precision measurements of free neutron beta decay with cold neutrons

Contact Info

Product

Resources

About