Wed·Feb 1, 2023Wednesday·February 1, 2023

1. 01*

   New experimental constraint on the ${}^{185}$W($n,\gamma$)${}^{186}$W cross section

   A. C. Larsen🇳🇴 · G. M. Tveten🇳🇴 · T. Renstrøm🇳🇴 · H. Utsunomiya · E. Algin · T. Ari-izumi · K. O. Ay🇹🇷 · F. L. Bello Garrote🇳🇴 · L. Crespo Campo🇳🇴 · F. Furmyr · S. Goriely🇧🇪 · A. Görgen🇳🇴 and 19 other authors

   In this work, we present new data on the ${}^{182,183,184}$W($\gamma ,n$) cross sections, utilizing a quasi-monochromatic photon beam produced at the NewSUBARU synchrotron radiation facility. Further, we have extracted the nuclear level density and $\gamma$-ray strength function of ${}^{186}$W from data on the ${}^{186}$W($\alpha ,{\alpha }^{\prime }\gamma$)${}^{186}$W reaction measured at the Oslo Cyclotron Laboratory. Combining previous measurements on the ${}^{186}$W($\gamma ,n$) cross section with our new ${}^{182,183,184}$W($\gamma ,n$) and ($\alpha ,{\alpha }^{\prime }\gamma$)${}^{186}$W data sets, we have deduced the ${}^{186}$W $\gamma$-ray strength function in the range of $1<E_{\gamma }<6$ MeV and $7<E_{\gamma }<14$ MeV. Our data are used to extract the level density and $\gamma$-ray strength functions needed as input to the nuclear-reaction code \textsf{TALYS}, providing an indirect, experimental constraint for the ${}^{185}$W($n,\gamma$)${}^{186}$W cross section and reaction rate. Compared to the recommended Maxwellian-averaged cross section (MACS) in the KADoNiS-1.0 data base, our results are on average lower for the relevant energy range $k_{B}T\in [5,100]$ keV, and we provide a smaller uncertainty for the MACS. The theoretical values of Bao \textit{et al.} and the cross section experimentally constrained on photoneutron data of Sonnabend \textit{et al.} are significantly higher than our result. The lower value by Mohr \textit{et al.} is in very good agreement with our deduced MACS. Our new results could have implications for the $s$-process and in particular the predicted $s$-process production of ${}^{186,187}$Os nuclei.

   nucl-exPRC(2023)·11 citations
2. 02*

   Measurement of the fraction of jet longitudinal momentum carried by ${\Lambda }_{\mathrm{c}}^{+}$ baryons in pp collisions

   ALICE Collaboration

   Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by ${\Lambda }_{\mathrm{c}}^{+}$ baryons, $z_{||}^{\mathrm{ch}}$, in hadronic collisions. The results are obtained in proton-proton (pp) collisions at $\sqrt{s}=13$ TeV at the LHC, with ${\Lambda }_{\mathrm{c}}^{+}$ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of $3\le p_{\mathrm{T}}^{{\Lambda }_{\mathrm{c}}^{+}}<15$ GeV/$c$ and $7\le p_{\mathrm{T}}^{\mathrm{jet}\mathrm{ch}}<15$ GeV/$c$, respectively. The $z_{||}^{\mathrm{ch}}$ distribution is compared to a measurement of ${\mathrm{D}}^0$-tagged charged jets in pp collisions as well as to PYTHIA 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as predicted by hadronisation models which include colour correlations beyond leading-colour in the string formation.

   nucl-exhep-exPRD(2024)·28 citations
3. 03*

   Extraction of neutron density distributions from high-statistics coherent elastic neutrino-nucleus scattering data

   D. Aristizabal Sierra🇨🇱

   Forthcoming fixed-target coherent elastic neutrino-nucleus scattering experiments aim at measurements with $\mathcal{O}(\text{tonne})$-scale detectors and substantially reduced systematic and statistical uncertainties. With such high quality data, the extraction of point-neutron distributions mean-square radii requires a better understanding of possible theoretical uncertainties. We quantify the impact of single-nucleon electromagnetic mean-square radii on the weak-charge form factor and compare results from weak-charge form factor parametrizations and weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors, including nucleon form factors $Q$-dependent terms up to order $Q^2$. We assess as well the differences arising from results derived using weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors and a model-independent approach based solely on the assumption of spherically symmetric nuclear ground state. We demonstrate the impact of the main effects by assuming pseudo-data from a one-tonne LAr detector and find that, among the effects and under the assumptions considered in this paper, weak-charge form factor parametrizations and weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors enable the extraction of the ${}^{40}\text{Ar}$ point-neutron distribution mean-square radius with a $\sim 15\%$ accuracy. With a substantial reduction of the beam-related neutron and steady-state backgrounds a $\sim 1\%$ precision extraction seems feasible, using either of the two approaches.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2023)·14 citations
4. 04*

   Dense Nuclear Matter Equation of State from Heavy-Ion Collisions

   Agnieszka Sorensen🇺🇸 · Kshitij Agarwal🇩🇪 · Kyle W. Brown🇺🇸 · Zbigniew Chajęcki🇺🇸 · Paweł Danielewicz🇺🇸 · Christian Drischler🇺🇸 · Stefano Gandolfi🇺🇸 · Jeremy W. Holt🇺🇸 · Matthias Kaminski🇺🇸 · Che-Ming Ko🇺🇸 · Rohit Kumar🇺🇸 · Bao-An Li🇺🇸 and 124 other authors

   The nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS.

   ↳ nucl-thnucl-exPPNP(2024)·285 citations
5. 05*

   Investigating the fission dynamics of the following neutron shell closed nuclei within a stochastic dynamical approach: 210Po, 212Rn, and 213Fr

   Divya Arora · P. Sugathan🇮🇳 · A. Chatterjee🇮🇳

   Dissipative dynamics of nuclear fission is a well confirmed phenomenon described either by a Kramers-modified statistical model or by a dynamical model employing the Langevin equation. Though dynamical models as well as statistical models incorporating fission delay are found to explain the measured fission observables in many studies, it nonetheless shows conflicting results for shell closed nuclei in the mass region 200. Analysis of recent data for neutron shell closed nuclei in excitation energy range 40$-$80 MeV failed to arrive at a satisfactory description of the data and attributed the mismatch to shell effects and/or entrance channel effects, without reaching a definite conclusion. In the present work we show that a well established stochastic dynamical code simultaneously reproduces the available data of pre-scission neutron multiplicities, fission and evaporation residue excitation functions for neutron shell closed nuclei ${}^{210}$Po and ${}^{212}$Rn and their isotopes ${}^{206}$Po and ${}^{214,216}$Rn without the need for including any extra shell or entrance channel effects. The calculations are performed by using a phenomenological universal friction form factor with no ad-hoc adjustment of model parameters. However, we note significant deviation, beyond experimental errors, in some cases of Fr isotopes.

   ↳ nucl-thnucl-exCPC(2023)·2 citations
6. 06*

   Perfect QCD -- a new Universal approach to soft QCD

   Peter Christiansen🇸🇪

   The ideas presented in this proceeding aims to be a first step towards a description of hadronic collisions where all soft processes are fundamentally strongly coupled and the same Universal strongly coupled physics drives both initial and final-state interactions. As it is not currently possible to derive such a picture from first principles, instead, an attempt to generalize the perfect liquid observation to a ``perfect QCD'' guiding principle is presented, focusing on implications for particle production in small systems. The first steps towards a microscopic model is taken by arguing that ``perfect QCD'' suggests that the screening in the initial state is so large that multi-parton interactions are of little or no importance. Instead, a target and projectile remnant is coherently excited and particle production is mainly driven by radiation in a qualitative similar manner as $e^{+}{e}^{-}\to q\bar{q}$. Finally, some of the possible implications of this ``excited remnant model'' are presented. It is argued that the time ordering of soft and hard physics can explain the absence of jet quenching in small systems and that the coherence scale of the projectile and target provides insights into what small systems will exhibit flow.

   ↳ hep-phnucl-exnucl-thRev.Mex.Fis.Suppl.(2022)·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.