Pion electroproduction amplitude

Truhlík, E.

doi:10.1103/physrevc.64.055501

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…This heavy-meson origin for the operator leads us to anticipate that with a scale Λ Q of about 1.2 GeV the coupling h 4 will be of order 1. In particular, if we used resonance saturation in the NN system [48] to estimate the size of this operator the first mesonic current that would contribute to the operator would be the ρa 1 γ current [49]. We now give arguments which demonstrate that physics at roughly this scale could indeed remedy the discrepancy between the experimental Q d and the result found from the mechanisms already discussed.…”

Section: Unitary Equivalence and The Consistent Treatment Of 1/m Corrmentioning

confidence: 76%

Chiral effective theory predictions for deuteron form factor ratios at lowQ²

Phillips

2007

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

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We use chiral effective theory (χET) to predict the deuteron form factor ratio G C /G Q as well as ratios of deuteron to nucleon form factors. These ratios are calculated to next-to-next-to-leading order. At this order the chiral expansion for the N N isoscalar charge operator (including consistently calculated 1/M corrections) is a parameter-free prediction of the effective theory. Use of this operator in conjunction with NLO and NNLO χET wave functions produces results that are consistent with extant experimental data for Q 2 < 0.35 GeV 2 . These χET wave functions predict a deuteron quadrupole moment G Q (Q 2 = 0) = 0.278-0.282 fm 2with the variation arising from short-distance contributions to this quantity. The variation is of the same size as the discrepancy between the theoretical result and the experimental value. This motivates the renormalization of G Q via a two-nucleon operator that couples to quadrupole photons. After that renormalization we obtain a robust prediction for the shape of G C /G Q at Q 2 < 0.3 GeV 2 . This allows us to make precise, model-independent predictions for the values of this ratio that will be measured at the lower end of the kinematic range explored at BLAST. We also present results for the ratio G C /G M .

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Section: Unitary Equivalence and The Consistent Treatment Of 1/m Corrmentioning

confidence: 76%

Chiral effective theory predictions for deuteron form factor ratios at lowQ²

Phillips

2007

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

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“…If one admits that in the soft pion limit only the nucleon Born terms contribute to the divergence of the current-current amplitudes, then one has the pion production amplitude which can provide information on g P . However, when one of the currents is axial, a contribution to the divergence of the current-current amplitudes from the pion pole term in the t-channel survives even in the soft pion limit [57][58][59][60]. A part of this contribution cancels the induced pseudoscalar term in the axial current and the remaining part is just the pion pole production amplitude, as one can expect intuitively.…”

Section: The Matrix Element Of the Axial Current ĵAmentioning

confidence: 99%

Radiative muon capture in hydrogen

Truhlík¹,

Khanna

2002

Phys. Rev. C

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We analyze the radiative capture of the negative muon in hydrogen using amplitudes derived within the chiral Lagrangian approach. Besides the leading and next to leading order terms, given by the well-known Rood-Tolhoek Hamiltonian, we extract from these amplitudes the corrections of the next order in 1/M (M is the nucleon mass). In addition, we estimate within the same formalism also the ∆(1232) isobar excitation effects and processes described by an anomalous Lagrangian. Using of the parameters of the model obtained from the analysis of the pion photoproduction, which restricts the arbitrariness of the πN ∆ and γN ∆ vertices off-shell, allows us to explain two times more of the discrepancy between the value g P CAC P of the induced pseudoscalar form factor g P , predicted by partial conservation of the axial current, and of g P extracted from the recent TRIUMF experiment, than the standard approach. Varying these parameters independently, one can remove the discrepancy completely.

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“…In fact there has been a quite heated disagreement over the question of whether or not pion electroproduction does give new information about either g p or g a (Bernard et al, 2001c;Guichon , 2001;Haberzettl , 2000Haberzettl , , 2001Truhlik , 2001).…”

Section: Other Few Body Processesmentioning

confidence: 99%

Induced pseudoscalar coupling of the proton weak interaction

2003

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The induced pseudoscalar coupling gp is the least well known of the weak coupling constants of the proton's charged-current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling gp has been accumulated. This data includes measurements of radiative and non radiative muon capture on targets ranging from hydrogen and few-nucleon systems to complex nuclei. Herein the authors review the theoretical underpinnings of gp, the experimental studies of gp, and the procedures and uncertainties in extracting the coupling from data. Current puzzles are highlighted and future opportunities are discussed.

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Pion electroproduction amplitude

Cited by 8 publications

References 30 publications

Chiral effective theory predictions for deuteron form factor ratios at lowQ²

Chiral effective theory predictions for deuteron form factor ratios at lowQ²

Radiative muon capture in hydrogen

Induced pseudoscalar coupling of the proton weak interaction

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Pion electroproduction amplitude

Cited by 8 publications

References 30 publications

Chiral effective theory predictions for deuteron form factor ratios at lowQ2

Chiral effective theory predictions for deuteron form factor ratios at lowQ2

Radiative muon capture in hydrogen

Induced pseudoscalar coupling of the proton weak interaction

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Product

Resources

About

Chiral effective theory predictions for deuteron form factor ratios at lowQ²

Chiral effective theory predictions for deuteron form factor ratios at lowQ²