Measurement of Muon Capture on the Proton to 1% Precision and Determination of the Pseudoscalar Coupling<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>g</mml:mi><mml:mi>P</mml:mi></mml:msub></mml:math>

Andreev, V. A.; Banks, Thomas; Carey, Robert M.; Case, T.; Clayton, Steven; Crowe, K. M.; Deutsch, J.; Egger, J.; Freedman, S. J.; Ganzha, V. A.; Gorringe, T. P.; Gray, F.; Hertzog, D. W.; Hildebrandt, M.; Kammel, P.; Kiburg, B.; Knaack, S.; Кравцов, П.; Krivshich, A.; Lauss, B.; Lynch, Kevin R.; Maev, E. M.; Maev, O.; Mulhauser, F.; Petitjean, C.; Petrov, G. E.; Prieels, R.; Schapkin, G. N.; Semenchuk, G. G.; Soroka, Mirosław; Tishchenko, V. G.; Vasilyev, A.; Vorobyov, A.A.; Взнуздаев, М.; Winter, P.

doi:10.1103/physrevlett.110.012504

Cited by 63 publications

(83 citation statements)

References 38 publications

(50 reference statements)

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“…This problem was resolved by the MuCap Collaboration at the Paul Scherrer Institute (PSI) which introduced an active, in situ, target, where ultra-pure hydrogen gas served both as the target as well as the muon detector, thus enabling a measurement of the muonic hydrogen capture rate at low density, where ppµ formation is suppressed. MuCap unambiguously determined the spin singlet muonic hydrogen capture rate Λ MuCap singlet = 715.6(7.4) s −1 [15,16] to 1% accuracy which, when corrected for an enhancement from radiative corrections [17], and using prevailing form factor values at the time impliedḡ MuCap P = 8.06 (55), in excellent agreement withḡ theory P = 8.26 (23), the predicted value.…”

Section: Introductionsupporting

confidence: 63%

Nucleon axial radius and muonic hydrogen—a new analysis and review

et al. 2018

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Weak capture in muonic hydrogen (μH) as a probe of the chiral properties and nucleon structure predictions of quantum chromodynamics (QCD) is reviewed. A recent determination of the axial-vector charge radius squared, [Formula: see text], from a model independent z expansion analysis of neutrino-nucleon scattering data is employed in conjunction with the MuCap measurement of the singlet muonic hydrogen capture rate, [Formula: see text], to update the induced pseudoscalar nucleon coupling [Formula: see text] derived from experiment, and [Formula: see text] predicted by chiral perturbation theory. Accounting for correlated errors this implies [Formula: see text], confirming theory at the 8% level. If instead, the predicted expression for [Formula: see text] is employed as input, then the capture rate alone determines [Formula: see text], or together with the independent z expansion neutrino scattering result, a weighted average [Formula: see text]. Sources of theoretical uncertainty are critically examined and potential experimental improvements are described that can reduce the capture rate error by about a factor of 3. Muonic hydrogen can thus provide a precise and independent [Formula: see text] value which may be compared with other determinations, such as ongoing lattice gauge theory calculations. The importance of an improved [Formula: see text] determination for phenomenology is illustrated by considering the impact on critical neutrino-nucleus cross sections at neutrino oscillation experiments.

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Section: Introductionsupporting

confidence: 63%

Nucleon axial radius and muonic hydrogen—a new analysis and review

et al. 2018

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“…In the left panel, the experimental curve is given by a dipole form with the RMS radius of 0.67(1) fm [19,20], while the red dashed curve in the right panel is given by the pion-pole dominance model. The experimental data points in the right panel are given by muon capture [58,59] and pion electroproduction [24]. scheme [53].…”

Section: Axial-vector Fa and Induced Pseudoscalar Fp Form Factorsmentioning

confidence: 99%

Nucleon form factors on a large volume lattice near the physical point in 2+1 flavor QCD

et al. 2018

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We present results for the isovector nucleon form factors measured on a 96 4 lattice at almost the physical pion mass with a lattice spacing of 0.085 fm in 2+1 flavor QCD. The configurations are generated with the stout-smeared O(a)-improved Wilson quark action and the Iwasaki gauge action at β=1.82. The pion mass at the simulation point is about 146 MeV. A large spatial volume of (8.1 fm) 3 allows us to investigate the form factors in the small momentum transfer region. We determine the isovector electric radius and magnetic moment from nucleon electric (GE) and magnetic (GM ) form factors as well as the axial-vector coupling gA. We also report on the results of the axial-vector (FA), induced pseudoscalar (FP ) and pseudoscalar (GP ) form factors in order to verify the axial Ward-Takahashi identity in terms of the nucleon matrix elements, which may be called as the generalized Goldberger-Treiman relation.

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“…The axial form factor, G A (Q 2 ), and the induced pseudoscalar form factor,G P (Q 2 ), enter the description of (quasi-)elastic neutrino-nucleon scattering [5][6][7][8] and exclusive pion electroproduction [9][10][11][12] (e.g., e − p → π − pν). They can also be measured in muon capture [13][14][15][16]. For reviews see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

Solving the PCAC puzzle for nucleon axial and pseudoscalar form factors

et al. 2019

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It has been observed in multiple lattice determinations of isovector axial and pseudoscalar nucleon form factors, that, despite the fact that the partial conservation of the axialvector current is fulfilled on the level of correlation functions, the corresponding relation for form factors (sometimes called the generalized Goldberger-Treiman relation in the literature) is broken rather badly. In this work we trace this difference back to excited state contributions and propose a new projection method that resolves this problem. We demonstrate the efficacy of this method by computing the axial and pseudoscalar form factors as well as related quantities on ensembles with two flavors of improved Wilson fermions using pion masses down to 150 MeV. To this end, we perform the z-expansion with analytically enforced asymptotic behaviour and extrapolate to the physical point.

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Measurement of Muon Capture on the Proton to 1% Precision and Determination of the Pseudoscalar CouplinggP

Cited by 63 publications

References 38 publications

Nucleon axial radius and muonic hydrogen—a new analysis and review

Nucleon axial radius and muonic hydrogen—a new analysis and review

Nucleon form factors on a large volume lattice near the physical point in 2+1 flavor QCD

Solving the PCAC puzzle for nucleon axial and pseudoscalar form factors

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