Wed·Dec 21, 2022Wednesday·December 21, 2022

1. 01*

   Low $p_T$ direct photon production at RHIC measured with PHENIX

   Roli Esha (for the PHENIX Collaboration)🇺🇸

   PHENIX has used the versatility of RHIC to map out low $p_T$ direct photon production as function of collision system size and beam energy. For systems with a size corresponding to a $d{N}_{ch}/d\eta$ larger than 20-30, we observe a large yield of direct photons, a large azimuthal anisotropy with respect to the reaction plane, and a characteristic centrality dependence of $d{N}_{\gamma }/dy\propto (d{N}_{ch}/d\eta {)}^{\alpha }$, with $\alpha \sim$ 1.2. \\ In this proceeding, we will present new results from Au+Au collisions at $\sqrt{s_{NN}}$ = 39, 62.4 and 200 GeV. After subtracting the prompt photon component, the inverse slope for the $p_T$ range from 1-2 GeV/$c$ is 250 MeV/$c$, but increases to about 400 MeV/$c$ for the range from 2 to 4 GeV/$c$. Within the experimental uncertainty, there is no indication of a system size dependence of the inverse slope. Furthermore, the system size dependence of the yield, expressed through the power $\alpha$, remains independent of $p_T$ over the entire observed range from 1 to 6 GeV/$c$. Like the large yield and azimuthal anisotropy, these features, while qualitatively consistent with the emission of thermal photons from the quark gluon plasma, elude a quantitative description through theoretical model calculations.

   nucl-exActa Phys.Polon.Supp.(2023)·1 citation
2. 02*

   Improving Fission-product Decay Data for Reactor Applications: Part I -- Decay Heat

   A.L. Nichols🇬🇧 · P. Dimitriou🇦🇹 · A. Algora🇪🇸 · M. Fallot🇫🇷 · L. Giot🇫🇷 · F.G. Kondev🇺🇸 · T. Yoshida🇯🇵 · M. Karny🇵🇱 · G. Mukherjee🇮🇳 · B.C. Rasco🇺🇸 · K.P. Rykaczewski🇺🇸 · A.A. Sonzogni🇺🇸 · J.L. Tain🇪🇸

   Effort has been expended to assess the relative merits of undertaking further decay-data measurements of the main fission-product contributors to the decay heat of neutron-irradiated fissile fuel and related actinides by means of Total Absorption Gamma-ray Spectroscopy (TAGS/TAS) and Discrete Gamma-ray Spectroscopy (DGS). This review has been carried out following similar work performed under the auspices of OECD/WPEC-Subgroup 25 (2005-2007) and the International Atomic Energy Agency (2010, 2014), and various highly relevant TAGS measurements completed as a consequence of such assessments. We present our recommendations for new decay-data evaluations, along with possible requirements for total absorption and discrete high-resolution gamma-ray spectroscopy studies that cover approximately 120 fission products and various isomeric states.

   nucl-exEPJA(2023)·14 citations
3. 03*

   Radon Decays and Their Implications for Elementary Particle Physics

   C. Scarlett · E. Fischbach · B. Freeman · J. J. Coy · P. Edwards · R. Burkhart · O. Piatibratova · T. Monsue · A. Egoh · L. Mwibanda · A. Alsayegh

   This paper presents a new analysis of the observations of radon decay in an enclosed environment by the Geological Survey of Israel (GSI) between 2007 and 2012 [4]; for a more complete list of experiments performed by GSI on radon see also references [1-3]. The data exhibit a large peak around local noon followed by an abrupt drop, and by a second peak around 6PM local time. Additionally, there is also a very low amplitude peak occurring before daybreak. The salient features of the GSI radon decay data can be modeled as arising from a change in the radon decay rate, rather than due to the changes in the local concentration of radon (N0). Such a model may provide a clue to long theorized axionic, dark matter, interactions. Finally, new experimentation is suggested that can distinguish between changes in N0 versus changes in decay rate. Should a follow-up experiment show an effect similar to that seen in GSI, this could have significant implications for elementary particle physics.

   nucl-exhep-phnucl-th0 citations
4. 04*

   New insights into the pole parameters of the $\Lambda (1380)$, the $\Lambda (1405)$ and the $\Sigma (1385)$

   Daniel Sadasivan🇨🇱 · Maxim Mai🇺🇸 · Michael Döring🇺🇸 · Ulf-G. Meißner🇩🇪 · Felipe Amorim🇨🇱 · John Paul Klucik🇨🇱 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

   A coupled-channel S- and P-wave next-to-leading order chiral-unitary approach for strangeness $S=-1$ meson-baryon scattering is extended to include the new data from the KLOE and AMADEUS experiments as well as the $\Lambda \pi$ mass distribution of the $\Sigma (1385)$. The positions of the poles on the second Riemann sheet corresponding to the $\Sigma (1385)$ pole and the $\Lambda (1380)$ and $\Lambda (1405)$ poles as well as the couplings of these states to various channels are calculated. We find that the resonance positions and branching ratios are on average determined with about 20\% higher precision when including the KLOE and AMADEUS data. Additionally, for the first time, the correlations between the parameters of the poles are investigated and shown to be relevant. We also find that the $\Sigma (1385)$ has negligible influence on the properties of the $\Lambda$ states given the available data. Still, we identify isospin-1 cusp structures in the present solution in light of new measurements of ${\pi }^{\pm }\Lambda$ line-shapes by the Belle collaboration.

   ↳ nucl-thhep-phnucl-exFront.Phys.(2023)·17 citations
5. 05*

   Baryon Number Transport, Strangeness Conservation and $\Omega$-hadron Correlations

   Xiatong Wu🇺🇸 · Weijie Dong🇨🇳 · Xiaozhou Yu🇨🇳 · Hui Li🇨🇳 · Gang Wang🇺🇸 · Huan Zhong Huang🇺🇸 · Zi-Wei Lin🇺🇸

   Although strange quarks are produced in $s\bar{s}$ pairs, the ratio of ${\Omega }^{-}$ to ${\bar{\Omega }}^{+}$ is greater than one in heavy-ion collisions at lower RHIC energies. Thus the produced $\Omega$ hyperons must carry net baryon quantum numbers from the colliding nuclei. We present results of $K$-$\Omega$ correlations from AMPT model simulations of Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6 GeV, to probe dynamics for baryon number transport to mid-rapidities at this beam energy. We use both the default and string-melting versions to illustrate how hadronization schemes of quark coalescence and string fragmentations could leave imprints on such correlations. Implications on the measurements of these correlations with the STAR experiment at RHIC will also be discussed.

   ↳ nucl-thhep-exnucl-exEPJ Web Conf.(2023)·0 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.