Fri·Jul 12, 2024Friday·July 12, 2024

1. 01*

   Non-maximal entanglement of photons from positron-electron annihilation demonstrated using a novel plastic PET scanner

   P. Moskal · D. Kumar · S. Sharma · E.Y. Beyene · N. Chug · A. Coussat · C. Curceanu · E. Czerwinski · M. Das · K. Dulski · M. Gorgol · B. Jasinska and 16 other authors

   In state-of-the-art Positron Emission Tomography (PET), information about annihilation photon polarization is unavailable. Here, we present a PET scanner built from plastic scintillators, where annihilation photons primarily interact via the Compton effect, providing information about both photon polarization and propagation direction. Using this plastic-based PET, we determined the distribution of the relative angle between polarization planes of photons from positron-electron annihilation in a porous polymer. The amplitude of the observed distribution is smaller than predicted for maximally quantum-entangled two-photon states but larger than expected for separable photons. This result can be well explained by assuming that photons from pick-off annihilation are not entangled, while photons from direct and para-positronium annihilations are maximally entangled. Our result indicates that the degree of entanglement depends on the annihilation mechanism in matter, opening new avenues for exploring polarization correlations in PET as a diagnostic indicator.

   nucl-exphysics.med-phquant-phSci.Adv.(2025)·21 citations
2. 02*

   Centrality dependence of Lévy-stable two-pion Bose-Einstein correlations in $\sqrt{s_{{}_{NN}}}=200$ GeV Au$+$Au collisions

   PHENIX Collaboration: N.J. Abdulameer🇭🇺 · U. Acharya🇺🇸 · A. Adare🇺🇸 · C. Aidala🇺🇸 · N.N. Ajitanand🇺🇸 · Y. Akiba🇯🇵 · R. Akimoto🇯🇵 · H. Al-Ta'ani🇺🇸 · J. Alexander🇺🇸 · A. Angerami🇺🇸 · K. Aoki🇯🇵 · N. Apadula🇺🇸 and 390 other authors

   The PHENIX experiment measured the centrality dependence of two-pion Bose-Einstein correlation functions in $\sqrt{s_{{}_{NN}}}=200$~GeV Au$+$Au collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The data are well represented by Lévy-stable source distributions. The extracted source parameters are the correlation-strength parameter $\lambda$, the Lévy index of stability $\alpha$, and the Lévy-scale parameter $R$ as a function of transverse mass $m_T$ and centrality. The $\lambda (m_T)$ parameter is constant at larger values of $m_T$, but decreases as $m_T$ decreases. The Lévy scale parameter $R(m_T)$ decreases with $m_T$ and exhibits proportionality to the length scale of the nuclear overlap region. The Lévy exponent $\alpha (m_T)$ is independent of $m_T$ within uncertainties in each investigated centrality bin, but shows a clear centrality dependence. At all centralities, the Lévy exponent $\alpha$ is significantly different from that of Gaussian ($\alpha =2$) or Cauchy ($\alpha =1$) source distributions. Comparisons to the predictions of Monte-Carlo simulations of resonance-decay chains show that in all but the most peripheral centrality class (50%-60%), the obtained results are inconsistent with the measurements, unless a significant reduction of the in-medium mass of the ${\eta }^{\prime }$ meson is included. In each centrality class, the best value of the in-medium ${\eta }^{\prime }$ mass is compared to the mass of the $\eta$ meson, as well as to several theoretical predictions that consider restoration of $U_A(1)$ symmetry in hot hadronic matter.

   nucl-exPRC(2024)·12 citations
3. 03*

   A unitary coupled-channel three-body amplitude with pions and kaons

   Yuchuan Feng🇺🇸 · Fernando Gil🇪🇸 · Michael Döring🇺🇸 · Raquel Molina🇪🇸 · Maxim Mai🇺🇸 · Vanamali Shastry🇺🇸 · Adam Szczepaniak🇺🇸

   Three-body dynamics above threshold is required for the reliable extraction of many amplitudes and resonances from experiment and lattice QCD. The S-matrix principle of unitarity can be used to construct dynamical coupled-channel approaches in which three particles scatter off each other, re-arranging two-body subsystems by particle exchange. This paper reports the development of a three-body coupled-channel, amplitude including pions and kaons. The unequal-mass amplitude contains two-body S- and P-wave subsystems ("isobars") of all isospins, $I=0,1/2,1,3/2,2$, and it also allows for transitions within a given isobar. The $f_0(500)("\sigma "),f_0(980),\rho (700),K_0^{\ast }(700)("\kappa ")$, and $K^{\ast }(892)$ resonances are included, apart from repulsive isobars. Different methods to evaluate the amplitude for physical momenta are discussed. Production amplitudes for $a_1$ quantum numbers are shown as a proof of principle for the numerical implementation.

   ↳ nucl-thhep-lathep-phnucl-exPRD(2024)·27 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.