Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam

Märkisch, Bastian; Mest, Holger; Saul, Heiko; Wang, Xiangzun; Abele, H.; Dubbers, D.; Klopf, Michael; Petoukhov, A.; Roick, Christoph; Söldner, T.; Werder, Dominik

doi:10.1103/physrevlett.122.242501

Cited by 171 publications

(156 citation statements)

References 62 publications

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“…(15) is measured in neutron decay asymmetry studies, after correcting for residual recoil, weak magnetism and small O (α) corrections as discussed by Wilkinson [44] and Shann [45]. Corrections to the asymmetry reduce its magnitude by about 1% and correspondingly decrease g A by about 0.25% [42,43].…”

Section: Radiative Corrections To Neutron Decaymentioning

confidence: 99%

Radiative corrections to neutron and nuclear beta decays revisited

2019

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The universal radiative corrections common to neutron and super-allowed nuclear beta decays (also known as "inner" corrections) are revisited in light of a recent dispersion relation study that found +2.467(22)%, i.e. about 2.4σ larger than the previous evaluation. For comparison, we consider several alternative computational methods. All employ an updated perturbative QCD four-loop Bjorken sum rule (BjSR) defined QCD coupling supplemented with a nucleon form factor based Born amplitude to estimate axial-vector induced hadronic contributions. In addition, we now include hadronic contributions from low Q 2 loop effects based on duality considerations and vector meson resonance interpolators. Our primary result, 2.426(32)% corresponds to an average of a Light Front Holomorphic QCD approach and a three resonance interpolator fit. It reduces the dispersion relation discrepancy to approximately 1.1σ and thereby provides a consistency check. Consequences of our new radiative correction estimate, along with that of the dispersion relation result, for CKM unitarity are discussed. The neutron lifetime-gA connection is updated and shown to suggest a shorter neutron lifetime < 879 s. We also find an improved bound on exotic, non-Standard Model, neutron decays or oscillations of the type conjectured as solutions to the neutron lifetime problem, BR(n → exotics) < 0.16%.

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Section: Radiative Corrections To Neutron Decaymentioning

confidence: 99%

Radiative corrections to neutron and nuclear beta decays revisited

2019

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“…We use the same statistical approach and dataset as in the recent review in Ref. [33] (Table 4, 5 and 7), but also including the recent PERKEO-III measurement of the beta asymmetry in neutron decay, A n = 0.11985(21) [53]. We note that the errors of the average lifetime and beta asymmetries are re-scaledà la PDG to take into account tensions among various measurements.…”

Section: Neutron and Nuclear Beta Decaymentioning

confidence: 99%

Reactor neutrino oscillations as constraints on effective field theory

Falkowski

González–Alonso

Tabrizi

2019

J. High Energ. Phys.

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We study constraints on the Standard Model Effective Field Theory (SMEFT) from neutrino oscillations in short-baseline reactor experiments. We calculate the survival probability of reactor antineutrinos at the leading order in the SMEFT expansion, that is including linear effects of dimension-6 operators. It is shown that, at this order, reactor experiments alone cannot probe charged-current contact interactions between leptons and quarks that are of the (pseudo)vector (V±A) or pseudo-scalar type. We also note that flavor-diagonal (pseudo)vector coefficients do not have observable effects in oscillation experiments. In this we reach novel or different conclusions than prior analyses of non-standard neutrino interactions. On the other hand, reactor experiments offer a unique opportunity to probe tensor and scalar SMEFT operators that are offdiagonal in the lepton-flavor space. We derive constraints on the corresponding SMEFT parameters using the most recent data from the Daya Bay and RENO experiments.

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“…(33) syst. [40]. Then, u p , u n , u e and vν are Dirac bispinor wave functions of free fermions [9,47].…”

Section: Amplitude Of the Neutron β − -Decay With Contributions Omentioning

confidence: 99%

“…This agrees well with estimates of contributions of the second class currents, caused by derivative scalar ∂ µ (ψ p ψ n ) and pseudotensor ∂ ν (ψ p σ µν γ 5 ψ n ) nucleon currents proposed by Weinberg [36], to the neutron lifetime and correlation coefficients of the neutron β − -decays carried out by Gardner and Plaster [29,30] and Ivanov et al [12,13]. The contemporary experimental sensitivities 10 −4 or even better [39] of the experimental analyses of the parameters of the neutron β − -decays (see, for example, [40][41][42]) demand a theoretical background for the neutron lifetime and correlation coefficients of the neutron β − -decays with different polarizations of massive fermions at the level of 10 −5 [11][12][13][14]. As has been shown in [25]- [28] in the linear approximation the contributions of vector and axial-vector interactions beyond the SM can be absorbed by the matrix element V ud of the Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix and by the axial coupling constant λ (see also [9,[11][12][13]).…”

Section: Introductionmentioning

confidence: 99%

Precision analysis of pseudoscalar interactions in neutron beta decays

et al. 2020

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We analyze the contributions of the one-pion-pole exchange, caused by strong low-energy interactions, and the pseudoscalar interaction beyond the Standard Model (SM) to the correlation coefficients of the neutron β − -decays with polarized neutrons, polarized electrons and unpolarized protons. We show that the contribution of the one-pion-pole exchange is of order 10 −5 . The contributions of the one-pion-pole exchange and the pseudoscalar interaction beyond the SM are compared with the contributions of G-odd correlations or the contributions of second class hadronic currents of order 10 −5 calculated by Gardner and Plaster (Phys. Rev. C 87, 065504 (2013)) and by Ivanov et al. (Phys. Rev. C 98, 035503 (2018), Phys. Rev. D 99, 053004 (2019)). We find that in case of vanishing tensor and pseudoscalar interactions beyond the SM the Fierz interference term b can be induced of order b ∼ 10 −5 by the one-pion-pole exchange, caused by strong low-energy interactions.

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Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam

Cited by 171 publications

References 62 publications

Radiative corrections to neutron and nuclear beta decays revisited

Radiative corrections to neutron and nuclear beta decays revisited

Reactor neutrino oscillations as constraints on effective field theory

Precision analysis of pseudoscalar interactions in neutron beta decays

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