The kaon photoproduction is investigated at the threshold energy. We discuss ͑i͒ the difference between the pseudoscalar ͑PS͒ and the pseudovector ͑PV͒ coupling descriptions on the KNY interaction, ͑ii͒ the contributions of t-channel poles of vector and axial vector mesons, and ͑iii͒ the contributions of nucleon and hyperon resonances to the E 0 ϩ amplitude. We suggest that total cross sections near threshold can be used to estimate the leading coupling constant, g KN⌳ and to make clear which description is the better of PS and PV coupling schemes for this reaction from future experiments. ͓S0556-2813͑96͒01010-2͔PACS number͑s͒: 25.20. Lj, 25.80.Nv, 13.75.Jz

The kaon photoproduction is analyzed up to E Lab γ =2.0 GeV by using an isobaric model based on effective Lagrangians and by taking a cross symmetry into account. Both pseudovector and pseudoscalar couplings for kaonbaryon-baryon (baryon spin=1/2) interactions are considered with form factors. A vector meson(K * (890)), an axial vector meson(K 1 (1270)), nucleon resonances(J ≤ 5/2), and hyperon resonances(J ≤ 3/2) are treated as participating particles. By determining unknown coupling constants through a systematic fitting of the differential cross section, the total cross section, the single polarization observable, and the radiative kaon capture branching ratio to their experimental data, we find out a simple model which reproduces all the experimental data well.

The deuteron binding energy extracted from the reaction 1 H(n, γ) 2 H is reviewed with the exact relativistic formula, where the initial kinetic energy and the Doppler effect are taken into account. We find that the negligible initial kinetic energy of the neutron could cause a significant uncertainty which is beyond the errors available up to now. Therefore, we suggest an experiment which should include the detailed informations about the initial kinetic energy and the detection angle. It could reduce discrepancies among the recently reported values about the deuteron binding energy and pin down the uncertainty due to the Doppler broadening of γ ray.PACS numbers: 21.10. Dr, 11.80.Cr, 25.40.Lw, 27.10.+h The deuteron binding energy is one of the most important physical quantities in nuclear physics. This plays a central role in the determination of the neutron mass, and provides a critical reference energy for the determination of high-energy γ rays measured on the atomic-mass scale [1]. There are several articles to have measured and improved the deuteron binding energy more precisely than ever [1][2][3][4][5][6][7]. Some of them have reported their values as precisely as up to the order of several electron volts [1,2,4,6]. Usually, the deuteron binding energy is determined by adding the recoil energy of the deuteron to the measured energy of the γ ray which is emitted from the neutron capture reaction, 1 H(n, γ) 2 H. In the conventional non-relativistic treatment, there seems to be nothing to correct any more, because the initial kinetic energy of the neutron is assumed to be so small that it can be neglected safely. Actually, the kinetic energy of the neutron used in Ref.[1] is 0.056 eV and that of the thermalized neutron from the neutron source in Ref.[2,4,5] is assumed to be 0.025 eV at room temperature.However, if the two body collision process is treated relativistically, we demonstrate that such a small kinetic energy of the neutron causes a considerable uncertainty in the deuteron binding energy because of the Doppler effect. Even the very small neutron kinetic energy gives rise to a significant velocity of the n-p system in the laboratory frame. As a result, this moving source of the γ ray can be an origin for the Doppler effect. Naturally this Doppler effect depends on the angle of the γ ray detector with respect to the velocity of moving source. Therefore, the measured γ ray energy is expected to have an unavoidable uncertainty originating from this angle dependence. As will be shown later on, our estimation for the uncertainty shows about 25 eV maximally for the neutron initial kinetic energy of 0.056 eV and 14.0 eV for that of 0.025 eV, respectively. These values are so large compared to the reported error 2.3 eV [1], which comes from the γ ray detector itself.Let us suppose that two particles are initially at rest within an appropriate interaction distance, and they come together to form one body system by emitting a photon. In this situation, the center of momentum frame [12], which is an exact...

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The recent TRIUMF experiment for μ−p → nνμγ gave a surprising result that the induced pseudoscalar coupling constant gP was larger than the value obtained from μ−p → nνμ experiment by as much as 44%. Subsequent debates on the result gave rise to many theoretical calculations. Most of them were skeptical for the enlarged coupling constant gP. Therefore, one needs to reexamine the theoretical analysis of the matrix element of Beder and Fearing which was exploited for the extraction of the value in the experiment. In this report we analyse the matrix element from the viewpoint of electro-magnetic coupling schemes and suggest an additional term. This additional term plays an important role in restoring the standard value of gP.