Thu·Aug 1, 2024Thursday·August 1, 2024

1. 01*

   Considerations on measuring spin-spin correlation of hyeprons in heavy-ion experiments

   Diyu Shen🇨🇳 · Jinhui Chen🇨🇳 · Aihong Tang🇺🇸

   The significant global spin alignment observed for $\varphi$ mesons in heavy-ion collisions has sparked intense discussions about its origin and implications. One explanation suggests that fluctuations in the strong force field may introduce strong spin correlations between strange ($s$) and anti-strange ($\bar{s}$) quarks, leading to the global spin alignment of $\varphi$ mesons. Extending this line of research, the theoretical community has proposed studying the spin correlation between $\Lambda$ and $\bar{\Lambda }$ hyperons. In this paper, we construct experimental observables and make connections between them and the theoretical proposed quantities.

   ↳ nucl-thhep-exnucl-ex7 citations
2. 02*

   Electromagnetic $|G_E/G_M|$ ratios of hyperons at large timelike $q^2$

   G. Ramalho🇰🇷 · M.T. Peña🇵🇹 · K. Tsushima🇧🇷 · Myung-Ki Cheoun🇰🇷

   In recent years, it has become possible to measure not only the magnitude of the electric ($G_E$) and magnetic ($G_M$) form factors of spin $\frac{1}{2}$ baryons, but also to measure the relative phases of those quantities in the timelike kinematic region. Aiming to interpret present $|G_E/G_M|$ data on hyperons of the baryon octet, as well as to predict future data, we present model calculations of that ratio for large invariant 4-momentum square $q^2$ in the timelike region ($q^2>0$). Without any further parameter fitting,we extend to the timelike region a covariant quark model previously developed to describe the kinematic spacelike region ($q^2\le 0$) of the baryon octet form factors. The model takes into account both the effects of valence quarks and the excitations of the meson cloud which dresses the baryons. This application to the timelike region assumes an approximation based on unitarity and analyticity that is valid only in the large $q^2$ region. Using the recent data from BESIII we establish the regime of validity of this approximation. We report here that our results for the effective form factor (combination of $|G_E|$ and $|G_M|$) are in good agreement with the data already for $q^2$ values above 15 GeV${}^2$. In addition, a more conservative onset of the validity of the approximation is provided by the newly available $|G_E/G_M|$ data which suggest that our predictions may be compared against data for $q^2\ge$ 20 GeV${}^2$. This is expected in the near future, when the range of the present measurements is expanded to the 20--50 GeV${}^2$ region.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2024)·14 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.