arXiv subjects

Chang Xiong

Publications and source records attributed to Chang Xiong.

3 recordsLinked to original sources

arXiv2025

Triple top baryon $\Omega_{ttt}$

The recent observation of toponium by CMS and ATLAS has renewed interest in top quark bound states. In this work, we present an exploratory but quantitative study of the hypothetical triple-top baryon, denoted as $\Omega_{ttt}$, the only baryon that is governed by ultraviolet freedom. Using a variational method with an effective potential of $ttt$ that includes QCD, Higgs, and QED contributions, we estimate its mass to be around 514 GeV with a binding energy of about 4 GeV. We further discuss its possible production at future high-energy colliders, finding that the cross sections are extremely suppressed. The dominant weak decay channel is identified as $\Omega_{ttt}\to W^+W^+W^+bbb$, leading to complex multi-lepton and multi-jet final states. Our analysis, though approximate, demonstrates the distinctive features of $\Omega_{ttt}$ compared with other triply-heavy baryons such as $\Omega_{ccc}$ and $\Omega_{bbb}$, and may serve as a starting point for more refined approaches, including lattice QCD or effective field theory. This work highlights both the theoretical challenges and the potential opportunities in probing the strong interaction at unprecedented mass scales.

hep-ph↗

arXiv2025

Probing Yoctosecond Quantum Dynamics in Toponium Formation at Colliders

The formation of toponium, a bound state of top and anti-top quarks, provides an unprecedented system for investigating quantum state dynamics at ultrashort timescales. We explore two distinct phenomenological descriptions of this process: a 'wavelike' scenario emphasizing the role of quantum superposition at creation, and a 'particlelike' scenario where a finite formation time is governed by relativistic causality. Both descriptions are compatible with the principles of relativistic quantum field theory. We propose to distinguish these scenarios by exploiting the top quark's intrinsic lifetime ($\tau_t \sim 5.02 \times 10^{-25}$\,s) as a quantum chronometer. We simulate the cross-section ratio $R_b = \sigma(e^+e^- \to b\bar{b})/\sum_q \sigma(e^+e^- \to q\bar{q})$ ($q = u,d,s,c,b$) near $\sqrt{s} = 343$\,GeV at future lepton colliders (CEPC/FCC-ee). These distinct scenarios yield observable $R_b$ profiles, enabling $>5\sigma$ discrimination with 1500\,fb$^{-1}$ of data. Preliminary LHC data provide independent $2$--$3\sigma$ support. This framework establishes a collider-based method to explore time-dependent quantum phenomena in particle production with yoctosecond ($10^{-24}$\,s) resolution.

hep-ph↗

arXiv2019

The $ΔI$=2 bands in $^{109}$In: possible antimagnetic rotation

The high-spin structure of $^{109}$In was investigated with the $^{100}$Mo($^{14}$N, 5$n$)$^{109}$In fusion-evaporation reaction at CIAE, Beijing. Eleven new $γ$-rays of $^{109}$In were identified, by which the bandheads of the $ΔI$=2 rotational bands were confirmed. The configurations were assigned with the help of the systematic discussion. Furthermore, the rotational bands are compared with the tilted-axis cranking calculations based on a relativistic mean-field approach. The rotational bands involving the $1p1h$ excitation to the $π$$d_{5/2}$ and $π$$g_{7/2}$ orbitals are suggested as candidates for antimagnetic rotation based on the theoretical results.

nucl-ex↗