${{\mathit n}}$ $\rightarrow$ ${{\mathit p}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$ DECAY PARAMETERS

See the above “Note on Baryon Decay Parameters.” For discussions of recent results, see the references cited at the beginning of the section on the neutron mean life. For discussions of the values of the weak coupling constants ${\mathit g}_{{{\mathit A}}}$ and ${\mathit g}_{{{\mathit V}}}$ obtained using the neutron lifetime and asymmetry parameter$~\mathit A$, comparisons with other methods of obtaining these constants, and implications for particle physics and for astrophysics, see DUBBERS 1991 and WOOLCOCK 1991. For tests of the $\mathit V−\mathit A$ theory of neutron decay, see EROZOLIMSKII 1991B, MOSTOVOI 1996, NICO 2005, SEVERIJNS 2006, and ABELE 2008.

FIERZ INTERFERENCE TERM $\mathit b$ INSPIRE search

The coefficient of the Fierz interference term, $\mathit b$, probes additional contributions to the differential decay rate of the neutron from scalar or tensor current interactions, beyond the Standard Model.
S017A00
VALUE DOCUMENT ID TECN  COMMENT
$0.017$ $\pm0.020$ $\pm0.003$ 1
SAUL
2020
SPEC Cold ${{\mathit n}}$, polarized
1  In a combined fit SAUL 2020 extract this best fit value of the Fierz interference term $\mathit b$ and the values ${{\mathit A}}$ = $-0.1209$ $\pm0.0015$ and $\lambda $ = $-1.2792$ $\pm0.0060$. For $\mathit b$ it translates into a 90$\%$ CL region of $-0.018$ ${}\leq{}$ $\mathit b$ ${}\leq{}$ 0.052 as a function of ${{\mathit A}}$.
  References:
SAUL 2020
PRL 125 112501 Limit on the Fierz Interference Term b from a Measurement of the Beta Asymmetry in Neutron Decay