T. Yoshimoto | Searcharxiv

arXiv2026

First Synchrotron Injection Attempt into The SuperKEKB High Energy Ring

A synchrotron injection scheme for the SuperKEKB electron high-energy ring (HER) was implemented and experimentally evaluated as the first attempt with a top-up injection during beam collisions. The lattice at the HER injection point was configured to provide a large horizontal dispersion of -1.6 m, and the injection beam energy was accordingly set to +0.6% above the ring energy. Since the beam extraction system is located near the injection point, the optics design was constrained to ensure compatibility with its requirements. A systematic tuning procedure of the injection parameters has been established with turn-by-turn BPMs(TbT-BPMs) in the ring, by which the betatron amplitude of the injected beam was successfully removed. Using optimized ring optics, synchrotron injection into the HER was successfully demonstrated, followed by the establishment of stable collisions and the production of luminosity.

physics.acc-ph↗

arXiv1999

Dynamical Test of Constituent Quark Models with $πN$ Reactions

A dynamical approach is developed to predict the $πN$ scattering amplitudes starting with the constituent quark models. The first step is to apply a variational method to solve the three-quark bound state problem. The resulting wave functions are used to calculate the $N^* \to πN, ηN, πΔ$ vertex functions by assuming that the $π$ and $η$ mesons couple directly to quarks. These vertex functions and the predicted baryon bare masses then define a Hamiltonian for $πN$ reactions. We apply a unitary transformation method to derive from the constructed Hamiltonian a multi-channel and multi-resonance reaction model for predicting the $πN$ scattering amplitudes up to $W = 2$ GeV. With the parameters constrained by the $Δ(1232$) excitation, we have examined the extent to which the $πN$ scattering in $S_{11}$ channel can be described by the constituent quark models based on the one-gluon-exchange or one-meson-exchange mechanisms. It is found that the data seem to favor the spin-spin interaction due to one-meson-exchange and the tensor interaction due to one-gluon-exchange. A phenomenological quark-quark potential has been constructed to reproduce the $S_{11}$ amplitude.

nucl-th↗