The Status of the Pion-nucleon Coupling Constant
نویسنده
چکیده
A review is given of the various determinations of the different πNN coupling constants in analyses of the low-energy pp, np, pp, and πp scattering data. The most accurate determinations are in the energy-dependent partial-wave analyses of the NN data. The recommended value is f 2 = 0.075. A recent determination of f 2 by the Uppsala group from backward np cross sections is shown to be model dependent and inaccurate, and therefore completely uninteresting. We also argue that an accurate determination of f 2 using pp forward dispersion relations is not a realistic option. Invited talks given by J.J. de Swart at FBXV, the 15th Int. Conf. on Few Body Problems in Physics, held from July 22 to 26, 1997 in Groningen, The Netherlands, and at MENU97, the 7th Int. Symp. on Meson-Nucleon Physics, held from July 28 to August 1, 1997 in Vancouver, B.C., Canada. Published in TRIUMF Report TRI-97-1, 96 (1997).
منابع مشابه
Pion Contribution to Hyperon-Nucleon Forces
A. calculation is made of the forces between hyperons and nucleons under the assumption that the forces are due to the exchange of pions. The h. and Z are assumed to have spin —,and the same parity. The Hamiltonian is taken -to be the same as the static-model pion-nucleon Hamiltonian except for differences in isotopic spin and possibly in the strength of the coupling. The same approximations ar...
متن کاملMeasurement of the Weak Pion - Nucleon Coupling Constant , h 1 , in Parity - Violating Backward Pion
This proposal describes a measurement of the weak pion-nucleon coupling constant to a high level of accuracy using moderate beam time in a theoretically \clean" process. We propose to measure the parity-violating asymmetry in pion photoproduction o the proton, ~ p! n . This asymmetry is expected to be 2:3 10 , and can be measured to statistical uncertainty of 0:5 10 7 at Je erson Lab in Hall A....
متن کاملThe Pion-Nucleon Coupling Constant in QCD Sum Rules
The pion-nucleon coupling constant gπN is studied on the basis of the QCD sum rules. Both the Borel sum rules and the finite energy sum rules for gπN are used to examine the effects of higher dimensional operators (up to dim. 7) and αs corrections in the operator product expansion. Agreement with the experimental number is reached only when Sπ/SN is greater than one, where Sπ (SN ) is the conti...
متن کاملNucleon Properties in the Perturbative Chiral Quark Model
We apply the perturbative chiral quark model (PCQM) to analyse low-energy nucleon properties: electromagnetic form factors, meson-nucleon sigma-terms and pion-nucleon scattering. Baryons are described as bound states of valence quarks surrounded by a cloud of Goldstone bosons (π,K, η) as required by chiral symmetry. The model is based on the following guide lines: chiral symmetry constraints, f...
متن کاملNucleon mass and pion loops : Renormalization †
Using Dyson–Schwinger equations, the nucleon propagator is analyzed nonperturbatively in a field–theoretical model for the pion–nucleon interaction. Infinities are circumvented by using pion–nucleon form factors which define the physical scale. It is shown that the correct, finite, on–shell nucleon renormalization is important for the value of the mass–shift and the propagator. For physically a...
متن کاملIsospin Breaking in the Pion-Nucleon Coupling from QCD Sum Rules
We use QCD sum rules for the three point function of a pseudoscalar and two nucleonic currents in order to estimate the charge dependence of the pion nucleon coupling constant gNNπ coming from isospin violation in the strong interaction. The effect can be attributed primarily to the difference of the quark condensates < ūu > and < d̄d >. For the splitting (gppπ0−gnnπ0)/gNNπ we obtain an interval...
متن کامل