Wed·Jun 1, 2022Wednesday·June 1, 2022

1. 01*

   First measurement of massive virtual photon emission from N* baryon resonances

   R. Abou Yassine · J. Adamczewski-Musch · O. Arnold · E.T. Atomssa · M. Becker · C. Behnke · J.C. Berger-Chen · A. Blanco · C. Blume · M. Böhmer · L. Chlad · P. Chudoba and 118 other authors

   First information on the time-like electromagnetic structure of baryons in the second resonance region has been obtained from measurements of dielectron (e+ e-) invariant-mass and angular distributions in the quasi-free reaction $\pi -$ p $\to$ n e+ e- at $\sqrt{s_{\pi p}}$ = 1.49 GeV with the High Acceptance Di-Electron Spectrometer (HADES) at GSI using the pion beam impinging on a CH${}_2$ target. We find a total cross section $\sigma$ = 2.97 $\pm$ 0.07data $\pm$ 0.21acc $\pm$ 0.31Zeff $\mu$b. In complement to the analysis of the inclusive e+ e- channel, this data set provides a crucial test of the description of baryon time-like transitions. Approaches based on a Vector Meson Dominance amplitude containing direct photon and vector meson ($\rho$) couplings to the baryon provide a satisfactory agreement with the data. A good description is also obtained by electromagnetic time-like baryon transition form factors in a covariant spectator-quark model, pointing to the dominance of meson-cloud effects. The dielectron angular distributions exhibit the contributions of virtual photons (${\gamma }^{\ast }$) with longitudinal polarization, in contrast to real photons. The virtual photon angular dependence supports the dominance of J=3/2, I=1/2 contributions observed in both the ${\gamma }^{\ast }$n and the $\pi \pi$n channels.

   nucl-exPLB(2026)·21 citations
2. 02*

   Fresh look at experimental evidence for odderon exchange

   Zhu-Fang Cui🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪 · D. N. Triantafyllopoulos🇮🇹

   Theory suggests that in high-energy elastic hadron+hadron scattering, $t$-channel exchange of a family of colourless crossing-odd states -- the odderon -- may generate differences between $p\bar{p}$ and $pp$ cross-sections in the neighbourhood of the diffractive minimum. Using a mathematical approach based on interpolation via continued fractions enhanced by statistical sampling, we develop robust comparisons between $p\bar{p}$ elastic differential cross-sections measured at $\surd s=1.96$TeV by the D0 Collaboration at the Tevatron and function-form-unbiased extrapolations to this energy of kindred $pp$ measurements at $\surd s/\mathrm{TeV}=2.76,7,8,13$ by the TOTEM Collaboration at the LHC and a combination of these data with earlier cross-section measurements at $\surd s/\mathrm{GeV}=23.5,30.7,44.7,52.8,62.5$ made at the internal storage rings. Focusing on a domain that straddles the diffractive minimum in the $p\bar{p}$ and $pp$ cross-sections, we find that these two cross-sections differ at the $(2.2-2.6)\sigma$ level; hence, supply evidence with this level of significance for the existence of the odderon. If combined with evidence obtained through different experiment-theory comparisons, whose significance is reported to lie in the range $(3.4-4.6)\sigma$, one arrives at a $(4.0-5.2)\sigma$ signal for the odderon.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2023)·11 citations
3. 03*

   Simulation of Lindblad equations for quarkonium in the quark-gluon plasma

   Takahiro Miura🇯🇵 · Yukinao Akamatsu🇯🇵 · Masayuki Asakawa🇯🇵 · Yukana Kaida🇯🇵

   We study the properties of the Lindbladian quantum mechanical evolution of quarkonia with non-Abelian charges (color-singlet and octet) in the quark-gluon plasma. We confirm that heavy quark recoils in the Lindblad equation correctly thermalize quarkonium colorful states within statistical errors from the simulation method. We also demonstrate that the Lindblad equation in the dipole limit can provide an efficient alternative method, which is applicable to a finite time evolution before thermalization and dramatically reduces the numerical cost. Our findings will serve as a foundation for large-scale simulation of quarkonium dynamics in the relativistic heavy-ion collisions.

   ↳ nucl-thcond-mat.quant-gashep-phnucl-ex+1PRD(2022)·31 citations
4. 04*

   Production and characterization of a ${}^{222}$Rn-emanating stainless steel source

   Florian Jörg🇩🇪 · Guillaume Eurin🇩🇪 · Hardy Simgen🇩🇪

   Precise radon measurements are a requirement for various applications, ranging from radiation protection over environmental studies to material screening campaigns for rare-event searches. All of them ultimately depend on the availability of calibration sources with a known and stable radon emanation rate. A new approach to produce clean and dry radon sources by implantation of ${}^{226}$Ra ions into stainless steel has been investigated. In a proof of principle study, two stainless steel plates have been implanted in collaboration with the ISOLDE facility located at CERN. We present results from a complete characterization of the sources. Each sample provides a radon emanation rate of about 2 Bq, which has been measured using electrostatic radon monitors as well as miniaturized proportional counters. Additional measurements using HPGe and alpha spectrometry as well as measurements of the radon emanation rate at low temperatures were carried out.

   ↳ physics.ins-detnucl-exAppl.Radiat.Isot.(2023)·8 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.