arXiv subjects

Ryoji Enomoto

Publications and source records attributed to Ryoji Enomoto.

7 recordsLinked to original sources

arXiv1998

Direct CP violation in three-body decays of the $B$ meson by resonance effects

We discuss direct CP violation in three-body decays of $B$ meson such as $B^\pm \to K^\pmπ^+π^-$, which involves various intermediate resonance states, such as $B^\pm \to K^*_i π^\pm$ and $B^\pm \to ρK^\pm$, where $K^*_i$ represents the $πK$ resonance. Due to the large final state interaction phases of the resonances, the CP asymmetry can be as large as the 25% level near the kinematical region where the $K^*_i$ and $ρ$ resonances overlap. By examining a Dalitz plot of this mode and combining a measurement of the branching ratio for $B^\pm \to ρ^\pm K$, it is possible to extract the weak phase, $ϕ_3$= arg$(-V_{ud}V_{ub}^*/(V_{cd}V_{cb}^*))$, of the Kobayashi-Maskawa matrix.

hep-ph↗

arXiv1997

CP Violation via $ρω$ Interference

We consider $B^{\pm,0} \to ρ^0(ω)h^{\pm,0}$, where $ρ^0(ω)$ decays to $π^+π^-$ and $h$ is any hadronic final state, such as $π$ or $K$. We find a large direct CP asymmetry in B-meson decays via $ρω$ interference. A possible method to determine weak phases, such as $ϕ_{2,3}$, is discussed. The experimental feasibility is also shown.

hep-ph↗

arXiv1996

Direct CP violation of B meson via rho-omega interference

We investigate $B^{\pm,0}\rightarrow ρ^0 (ω)h^{\pm,0}$, where $ρ^0 (ω)$ decays to $π^+π^-$ and $h$ is any hadronic final states, such as $π$ or $K$. We find large direct $CP$ asymmetries via $ρ-ω$ interference. A possible determination of the weak phases, such as $ϕ_2={\rm arg}((V_{ud}V^*_{ub})/(V_{td}V^*_{tb}))$ and $ϕ_3={\rm arg}((V_{us}V^*_{ub})/(V_{ts}V^*_{tb}))$, is also discussed. We show the feasibility to detect the CP asymmetries in these channels by assuming an asymmetric $e^+e^-$ collider experiment. $10^{9}$ $B\bar B$ events are required for the detection of this effect.

hep-ph↗

arXiv1995

Observation of Highly Virtual Photon-Photon Collisions to Hadrons at TRISTAN

We have observed highly virtual ($Q^2>1.05 GeV^2$) photon-photon collisions to hadronic final states at $\sqrt{s_{e^+e^-}}=58 GeV$. The integrated luminosity of the data sample was 241pb$^{-1}$. Both scattered beam-electrons and scattered beam-positrons were detected using low-angle calorimeters (i.e., both photons were highly virtual, "double-tag"); we obtained 115 hadronic events with an estimated background of $10.2\pm1.1$. The cross section obtained was $4.11\pm0.66$pb in the $2 2$ GeV region, while the lowest order quark-parton model predicted 3.00pb.

hep-ex↗

arXiv1995

A possible correlation between EGRET Sources and an Air-Borne experiment

In 1989, an air-borne experiments (VEGA experiment) aiming at the detection of a few 10 GeV $γ$-ray were carried out. In these experiments, nine point-source candidates along the Galactic plane were reported. In these candidates, the five of five highest significance candidates positionally coincide with the EGRET galactic plane sources.

astro-ph↗

arXiv1995

Electron identification using the TOPAZ detector at TRISTAN

We present an electron-identification method using the time-projection chamber and the lead-glass calorimeter in the TOPAZ detector system. Using this method we have achieved good electron identification against hadron backgrounds over a wide momentum range in the hadronic events produced by both single-photon exchange and two-photon processes. Pion-rejection factors and electron efficiencies were 163 and 68.4\% for high-$P_T$ electrons and 137 and 42.7\% for low-$P_T$ electrons in the single-photon-exchange process, and 8600 and 36.0\% for the two-photon process, respectively.

hep-ex↗

arXiv1994

Test of Various Photocathodes

A test of various photocathodes was carried out. The tested materials were CsI, CsTe, their multi-layers and so on. The quantum efficiencies of the various materials were measured under a vacuum and/or after exposure to several kinds of gases.

hep-ex↗