arXiv subjects

L. Y. Dai

Publications and source records attributed to L. Y. Dai.

5 recordsLinked to original sources

arXiv2023

STCF Conceptual Design Report: Volume 1 -- Physics & Detector

The Super $τ$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $τ$-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies.

hep-ex↗

arXiv2015

On the Nature of X(4260)

We study the property of $X(4260)$ resonance by re-analyzing all experimental data available, especially the $e^+e^- \rightarrow J/ψ\,π^+π^-,\,\,\,ωχ_{c0}$ cross section data. The final state interactions of the $ππ$, $K\bar K$ couple channel system are also taken into account. A sizable coupling between the $X(4260)$ and $ωχ_{c0}$ is found. The inclusion of the $ωχ_{c0}$ data indicates a small value of $Γ_{e^+e^-}=23.30\pm 3.55$eV.

hep-ph↗

arXiv2013

Three pseudoscalar meson production in $e^+ e^-$ annihilation

We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity $e^+ e^- \rightarrow π^+ π^- (π^0, η)$ cross-sections in the energy regime populated by hadron resonances, namely $3 \, m_π \lsim E \lsim 2 \, \mbox{GeV}$. In addition we implement our results in the Monte Carlo generator PHOKHARA 7.0 and we simulate hadron production through the radiative return method.

hep-ph↗

arXiv2012

Pole Analysis of Unitarized One Loop $χ$PT Amplitudes - A Triple Channel Study

In a previous paper (Commun. Theor. Phys. 57 (2012) 841), we proposed a method to distinguish poles of different dynamical origin, in a unitarized amplitude of $ππ\, K\bar K$ system. That is based on the observation that `A Breit-Wigner resonance should exhibit two poles on different Riemann sheets which meet each other on the real axis when $N_c=\infty$'. In this paper, we extend our previous work (Commun.Theor.Phys. 57 (2012) 841) to the $ππ$-$K\bar K$-$ηη$ three channel system. We reconfirm most of the previous predictions. Especially the $f_0(980)$ is of $K\bar K$ molecule nature. Other poles, including the $σ$, are of Breit--Wigner type.

hep-ph↗

arXiv2011

Pole analysis on unitarized $SU(3)\times SU(3)$ one loop $χ$PT amplitudes

We analyze $ππ-K\bar{K}$ and $πη-K\bar{K}$ couple channel [1,1] matrix Padé amplitudes of $SU(3)\times SU(3)$ chiral perturbation theory. By fitting phase shift and inelasticity data, we determine pole positions in different channels ($f_0(980)$, $a_0(980)$,$f_0(600)$, $K_0^*(800)$, $K^*(892)$, $ρ(770)$) and trace their $N_c$ trajectories. We stress that a couple channel Breit--Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when $N_c=\infty$. Poles are hence classified using this criteria and we conclude that $K^*(892)$ and $ρ(770)$ are unambiguous Breit--Wigner resonances. For scalars the situation is much less clear. We find that $f_0(980)$ is a molecular state rather than a Breit--Wigner resonance, while $a_0(980)$, though behaves oddly when varying $N_c$, does maintain a twin pole structure.

hep-ph↗