Proposal of Direct Search for Strongly Bound States of ppbar, npbar Systems with High Intensity and Collective pbar beam

In this letter, we discuss the possibility to look for the direct evidence of the existence of the ppbar and npbar bound states. Measurement of the single \gamma ray from the ppbar and npbar systems at rest can directly confirm whether the X(1860) and X(1835) are the resonances which are strongly coupled to ppbar. In addition to the neutral candidate, a charged resonance $X^-$ is also proposed to be searched for in npbar channel. We find that the data from the Crystal Barrel experiment at LEAR/CERN can be used to confirm the X(1835) observed by BES Collaboration. The possibility of measuring the $\gamma$ spectrum below 100 MeV at the new experiment with cold high intensity \pbar beam at GSI is discussed. These new techniques can be used to probe the structure of the X(1860) and X(1835) in the future.Comment: Accepted by Mod. Phys. Lett.

Study of Scalar Mesons at BES-II

Recent results from BES-II experiment on hadron spectroscopy using \jpsi and $\psi^\prime$ data samples collected in $e^+e^-$ annihilation are presented, including study of the scalar particles in \jpsi radiative and hadronic decays, the observation of X(1810) in $J/\psi \to \gamma \phi \omega$, as well as pair productions of scalars in $\chi_{c0}$ hadronic decays.Comment: Talk on "Hadron spectroscopy at BES" at "From Phi to Psi" Workshop February 27 - March 2, 2006, Novosibirsk, Russi

On the Pulse Shaping for Delay-Doppler Communications

In this paper, we study the pulse shaping for delay-Doppler (DD) communications. We start with constructing a basis function in the DD domain following the properties of the Zak transform. Particularly, we show that the constructed basis functions are globally quasi-periodic while locally twisted-shifted, and their significance in time and frequency domains are then revealed. We further analyze the ambiguity function of the basis function, and show that fully localized ambiguity function can be achieved by constructing the basis function using periodic signals. More importantly, we prove that time and frequency truncating such basis functions naturally leads to approximate delay and Doppler orthogonalities, if the truncating windows are periodic within the support. Motivated by this, we propose a DD Nyquist pulse shaping scheme considering signals with periodicity. Finally, our conclusions are verified by using various strictly or approximately periodic pulses

An Investigation of University Students' Classroom Seating Choices

The classroom is crucial for students, and seating position within the classroom can affect students’ performance. This study conducted a survey to investigate the relationship between seating zones and academic performance among 174 university students in Beijing. The results revealed differences in student performance in terms of seating position in small- and medium-sized traditional classrooms. However, the results did not indicate a similar hierarchy of student performance in terms of seating zones in larger traditional classrooms, horseshoe classrooms, collaboration classrooms, and computer classrooms. Additionally, the results revealed that most students considered the layout of a classroom to affect their performance