121660455
Propagation of a Dirac particle. A path integral approach
Rigorous path integral formulas are given which represent, in two space‐time dimensions, the fundamental solution of the Cauchy problem for the Dirac equation as well as the retarded and advanced propagators for the Dirac particle. It is also shown that the theory can be applied to a free particle and a particle in a central electric field in four space‐time dimensions and reveals some aspects of the path integral. Heuristically discussed is the connection with the phase space path integral or Hamiltonian path integral.
123591192
A Comment on Spontaneous Breaking of Chiral Symmetry
124892982
Investigation of Strangeness Photoproduction near the Threshold at ELPH, Tohoku University
Masashi Kaneta1, Brian Beckford1, Petr Bydžovský2, Takeshi Fujibayashi1, Takao Fujii1, Yu Fujii1, Kenta Futatsukawa1, Toshiyuki Gogami1, Yuncheng Han3, Osamu Hashimoto1 ∗, Kentaro Hirose4, Kenji Hosomi1, Ryotarou Honda1, Aran Iguchi1, Takatsugu Ishikawa4, Hiroki Kanda1, Yusuke Kaneko1, Yuma Kasai1, Taito Kawasaki1, Chigusa Kimura1, Shogo Kiyokawa1, Takeshi Koike1, Kazushige Maeda1, Nayuta Maruyama1, Masao Matsubara1, Koji Miwa1, Yohei Miyagi1, Sho Nagao1, Satoshi N. Nakamura1, Takashi Nishizawa1, Akira Okuyama1, Miloslav Sotona2,∗, Tadaaki Tamae4, Hirokazu Tamura1, Kyo Tsukada1, Nobu Terada1, Tieshan Wang3, Fumiya Yamamoto1, Takeshi O. Yamamoto1, and Hirohito Yamazaki4 (the NKS2 collaboration)
120389194
In memory of Osamu Hashimoto
120162764
Study of Strangeness Photoproduction on the Neutron in the Threshold Region
Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K0 with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K0 + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K1, as ~ −1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K+ Λ.
123696966
Measurement of Charged Pion Photoproduction at ELPH
We investigated the charged pion photoproduction on the deuteron in the energy region Eγ = 0.65− 1.1 GeV at Research Center for Electron Photon Science (ELPH), Tohoku University. The photon absorption by a nucleus mainly takes place on a single nucleon at energies above the first resonance region. The rest nucleons are called as the spectator and this process is called as the quasi-free process. The pion is emitted in the subsequent de-excitation process of the nucleon resonance excited through the absorption of the photon. The deuteron is the loosely bound system of the proton and the neutron and the photoreaction on it is considered to be dominated by the quasi-free process. However, significant contribution of the two nucleon absorption process in the π+π− photoproduction on the deuteron was measured in the energy region from 0.6 to 1.1 GeV[1, 2]. The importance of the nucleon resonances and the intermediate and final state interaction was suggested by the theoretical studies[3, 4]. For the detailed study of the intermediate states, precise experimental data, not only the total cross section but also the differential cross sections are required. The ABC effect [5] is a nuclear fusion reaction which is known to be related to the excitation of the two nucleon resonances (ΔΔ) in the intermediate state and their interaction. It is distinguished by a structure in the mass distribution of isoscalar pion pair[6, 7, 8]. One of our aim is the search for the ABC like effect in the photon induced double pion production reaction on the deuteron in the analysis of the similar final state with ABC effect (γd → π+π−d) and the explicit ΔΔ excitation (γd → ΔΔ → π+π−pn). The reactions d(γ, π+π−d) and d(γ, π+π−p)n were measured using the Neutral Kaon Spectrometer 2 (NKS2) at ELPH. The NKS2 is the magnetic spectrometer with the geometrical acceptance roughly 1/4 of the whole solid angle, dedicated for the multi-particle tracking. By refining the calibration of the detectors and the tracking procedures, the increased mass reconstruction resolution enabled us the efficient identification of these reactions with three charged particles in the final state. Simulation studies have been carried out for the extraction of the contributions of the intermediate states. We report on the current status of the analysis for the derivation of the cross sections of these reactions with the extraction of the intermediate states.