Tue·Feb 28, 2023Tuesday·February 28, 2023

1. 01*

   Searching for resonance states in ${}^{22}$Ne($p,\gamma$)${}^{23}$Na

   D. P. Carrasco-Rojas🇺🇸 · M. Williams🇨🇦 · P. Adsley🇺🇸 · L. Lamia🇮🇹 · B. Bastin🇫🇷 · T. Faestermann🇩🇪 · C. Fougeres🇫🇷 · F. Hammache🇫🇷 · D. S. Harrouz🇫🇷 · R. Hertenberger🇩🇪 · M. La Cognata🇮🇹 · A. Meyer🇫🇷 and 7 other authors

   Background: Globular clusters show strong correlations between different elements, such as the well-known sodium-oxygen anticorrelation. One of the main sources of uncertainty in this anticorrelation is the ${}^{22}$Ne($p,\gamma$)${}^{23}$Na reaction rate, due to the possible influence of an unobserved resonance state at $E_{\mathrm{x}}=8862$ keV ($E_{\mathrm{r},c.m.}=68$ keV). The influence of two higher-lying resonance states at $E_{\mathrm{x}}=8894$ and $9000$ keV has already been ruled out by direct ${}^{22}$Ne($p,\gamma$)${}^{23}$Na measurementsPurpose: To study excited states in ${}^{23}$Na above the proton threshold to determine if the unconfirmed resonance states in ${}^{23}$Na exist. Methods: The non-selective proton inelastic scattering reaction at low energies was used to search for excited states in ${}^{23}$Na above the proton threshold. Protons scattered from various targets were momentum-analysed in the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratorium, Munich, Germany. Results: The resonance states previously reported at $E_{\mathrm{x}}=8862$, $8894$ and $9000$ keV in other experiments were not observed in the present experiment at any angle. This result, combined with other non-observations of these resonance states in most other experiments, results in a strong presumption against the existence of these resonance states. Conclusions: The previously reported resonance states at $E_{\mathrm{x}}=8862$, $8894$ and $9000$ keV are unlikely to exist and should be omitted from future evaluations of the ${}^{22}$Ne($p,\gamma$)${}^{23}$Na reaction rates. Indirect studies using low-energy proton inelastic scattering are a simple and yet exceptionally powerful tool in helping to constrain astrophysical reaction rates by providing non-selective information of the excited states of nuclei.

   nucl-exPRC(2023)·5 citations
2. 02*

   Proton Charge Radius from Lepton Scattering

   Weizhi Xiong🇨🇳 · Chao Peng🇺🇸

   Protons are bound states of the strong interaction governed by Quantum Chromodynamics (QCD). Its charge radius ($r_E^p$) is an important quantity as it characterizes the spatial distribution of the proton's charge, which is carried by the quarks. On the other hand, the proton charge radius is an essential physical input for the bound-state Quantum Electrodynamic (QED) calculations for the hydrogen atomic energy levels. Nevertheless, the large discrepancy between $r_E^p$ measurements from muonic hydrogen spectroscopy, and those from $ep$ elastic scattering and ordinary hydrogen spectroscopy, have been puzzling physicists for over a decade. Tremendous efforts, in both theoretical and experimental sides, have been dedicated to providing various insights into this puzzle, yet certain issues still remain unresolved, particularly in the field of lepton scatterings. This review will focus on $r_E^p$ measurements using lepton scatterings, the recent theoretical and experimental developments in this field, as well as future experiments using this technique.

   nucl-exhep-exhep-phnucl-thUniverse(2023)·27 citations
3. 03*

   Experimental evidence of the effect of nuclear shells on fission dissipation and time

   D. Ramos🇫🇷 · M. Caamano🇪🇸 · F. Farget🇫🇷 · C. Rodriguez-Tajes🇪🇸 · A. Lemasson🇫🇷 · C. Schmitt🇫🇷 · L. Audouin🇫🇷 · J. Benlliure🇪🇸 · E. Casarejos🇪🇸 · E. Clement🇫🇷 · D. Cortina🇪🇸 · O. Delaune🇫🇷 and 11 other authors

   Nuclear fission is still one of the most complex physical processes we can observe in nature due to the interplay of macroscopic and microscopic nuclear properties that decide the result. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations, and scarce experimental data make it poorly understood. In this letter, we present the first experimental determination of the dissipation energy in fission as a function of the fragment split, for three different fissioning systems. The amount of dissipation was obtained through the measurement of the relative production of fragments with even and odd atomic numbers with respect to different initial fission energies. The results reveal a clear effect of particular nuclear shells on the dissipation and fission dynamics. In addition, the relative production of fragments with even and odd atomic numbers appears as a potential contributor to the long-standing problem of the time scale in fission.

   nucl-exnucl-thPRC(2023)·9 citations
4. 04*

   Measurement of reactor thermal neutron fluence of NTD-Ge by activation High-Purity Ge itself

   Kangkang Zhao🇨🇳 · Mingxuan Xue🇨🇳 · Haiping Peng🇨🇳 · Yunlong Zhang · Zhiyong Zhang · Zizong Xu🇺🇸 · Xiaolian Wang🇨🇳

   In neutron transmutation doped germanium, the thermal neutron fluence of reactor irradiation is as high as 10${}^{18}$~n$\cdot$cm${}^{-2}$. For radiological safety reasons, general Co or Au neutron flux monitors cannot be easily used. We have experimentally demonstrated the feasibility of measuring the X-rays emitted by the NTD-Ge itself to determine the absolute thermal neutron fluence for the first time. A Micro-Megas Detector (MMD) and a Silicon Drift Detector (SDD) are set up to detect the tagging KX-rays with 9.2 keV and 10.3 keV cascading from the decays of ${}^{71}$Ge. Combined the detection efficiencies calculated by GEANT4, neutron fluence results given with proper accuracy by MMD and SDD are in a good agreement with each other.

   ↳ physics.ins-dethep-exnucl-ex0 citations
5. 05*

   Radiative decays of the spin-$2$ partner of $X(3872)$

   Pan-Pan Shi🇨🇳 · Jorgivan M. Dias🇨🇳 · Feng-Kun Guo🇨🇳

   It has been generally expected that the $X(3872)$ has a spin-2 partner, $X_2$, with quantum numbers $J^{PC}=2^{++}$. In the hadronic molecular model, its mass was predicted to be below the $D^{\ast }{\bar{D}}^{\ast }$ threshold, and the new structure reported in the $\gamma \psi (2S)$ invariant mass distribution by the Belle Collaboration with mass $M=(4014.3\pm 4.0\pm 1.5)$ MeV and decay width $\Gamma =(4\pm 11\pm 6)$ MeV, with a global significance of 2.8 $\sigma$, is a nice candidate for it. We consider the radiative decay widths for the $X_2\to \gamma \psi$ with $\psi =J/\psi ,\psi (2S)$ treating the $X_2$ as a $D^{\ast }{\bar{D}}^{\ast }$ shallow bound state, and estimate the events of $X_2$ in two-photon collisions that can be collected in the $\gamma J/\psi \to \gamma {\ell }^{+}{\ell }^{-}$ ($\ell =e,\mu$) final states at Belle. Based on the upper limit for the ratio of decay widths of $X(3872)\to \gamma \psi (2S)$ and $X(3872)\to \gamma J/\psi$ measured by BESIII, we predict the similar ratio $\Gamma (X_2\to \gamma \psi (2S))/\Gamma (X_2\to \gamma J/\psi )$ to be smaller than $1.0$. We suggest searching for the $X_2$ signal in the $\gamma J/\psi$ invariant mass distribution via two-photon fusions. The results will lead to insights into both the $X(3872)$ and the new structure observed by Belle.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2023)·19 citations
6. 06*

   Effect of time-varying electromagnetic field on Wiedemann-Franz law in a hot hadronic matter

   Kamaljeet Singh🇮🇳 · Jayanta Dey🇮🇳 · Raghunath Sahoo🇮🇳 · Sabyasachi Ghosh🇮🇳

   We have estimated the electrical and thermal conductivity of a hadron resonance gas for a time-varying magnetic field, which is also compared with constant and zero magnetic field cases. Considering the exponential decay of electromagnetic fields with time, a kinetic theory framework can provide the microscopic expression of electrical and thermal conductivity in terms of relaxation and decay times. In the absence of the magnetic field, only a single time scale appears, and in the finite magnetic field case, their expressions carry two-time scales, relaxation time and cyclotron time period. Estimating the conductivities for HRG matter in three cases -- zero, constant, and time-varying magnetic fields, we have studied the validity of the Wiedemann-Franz law. We noticed that at a high-temperature domain, the ratio saturates at a particular value, which may be considered as Lorenz number of the hadron resonance gas. With respect to the saturation values, the deviation of the Wiedemann-Franz law has been quantified at the low-temperature domain. For the first time, the present work sketches this quantitative deviation of the Wiedemann-Franz law for hadron resonance gas at a constant and a time-varying magnetic field.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·23 citations
7. 07*

   New type of hydrogenlike charm-pion or charm-kaon matter

   Si-Qiang Luo🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiang Liu🇨🇳

   Borrowing the structures of the hydrogen atom, molecular ion, and diatomic molecule, we predict the nature of a new type of hydrogenlike charm-pion or charm-kaon matter that could be obtained by replacing the proton and electron in hydrogen matter with a charmed meson and a pion or a kaon, respectively. We find that the spectra of the atom, molecular ion, and diatomic molecule can be obtained simultaneously with the Coulomb potential for the hydrogen, the charm-pion, and the charm-kaon systems. The predicted charm-pion matter also allows us to explore the mass shift mediated by the strong interaction. For the charm-pion and charm-kaon systems, the strong interactions could lead to binding energy shifts. Our calculations suggests that the binding energy shifts in charm-pion systems are in the order of several to tens of eV. For the charm-kaon systems, the results are in the order of tens to hundreds of eV. Exploring hydrogenlike charm-pion matter must lead to new demands for high-precision experiments.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·7 citations
8. 08*

   Evidence of Hexadecapole Deformation in Uranium-238 at the Relativistic Heavy Ion Collider

   Wouter Ryssens🇧🇪 · Giuliano Giacalone🇩🇪 · Björn Schenke🇺🇸 · Chun Shen🇺🇸

   There is strong evidence of the failure of hydrodynamic simulations of the quark-gluon plasma (QGP) to reproduce data on the elliptic flow of particles in relativistic collisions of ${}^{238}$U nuclei at the BNL Relativistic Heavy Ion Collider (RHIC). We demonstrate that this failure is caused by an inappropriate implementation of well-deformed ions, such as ${}^{238}$U, in the hydrodynamic framework. Past studies have identified the deformation of the nuclear surface with that of the nuclear volume, though these are different concepts. In particular, a volume quadrupole moment can be generated by both a surface hexadecapole and a surface quadrupole moment. This feature was so far neglected in the modeling of heavy-ion collisions, and is particularly relevant for nuclei like ${}^{238}$U, which is both quadrupole- and hexadecapole-deformed. With rigorous input from Skyrme density functional calculations, we show that correcting for such effects in the implementation of nuclear deformations in hydrodynamic simulations restores agreement with BNL RHIC data. This brings consistency to the results of nuclear experiments across energy scales, and demonstrates the impact of the hexadecapole deformation of ${}^{238}$U on high-energy collisions.

   ↳ nucl-thhep-exhep-phnucl-exPRL(2023)·90 citations
9. 09*

   Isolated photon production in $pp$ collisions at forward rapidities and high multiplicity events

   Yuri N. Lima🇧🇷 · André V. Giannini🇧🇷 · Victor P. Goncalves🇧🇷

   The production of isolated photons in high multiplicity events is investigated considering the Color Glass Condensate (CGC) formalism. The associated cross-section for proton - proton collisions is estimated considering three distinct solutions of the Balitsky - Kovchegov (BK) equation and predictions for the normalized photon yield as a function of the multiplicities of co - produced charged particles are presented. We predict the increasing of the yield with the multiplicity, with the slope being smaller for larger rapidities. As the isolated photon production is not affected by the fragmentation process, a future experimental investigation of this process in current high energy hadronic colliders is ideal to test the treatment of high multiplicity events using the CGC formalism, previously applied only for the production of hadronic final states.

   ↳ hep-phhep-exnucl-exnucl-thEPJA(2024)·7 citations
10. 10*

    Rapidity scan with multistage hydrodynamic and statistical thermal models

    Lipei Du🇨🇦 · Han Gao🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    We calibrate a (3+1)-dimensional multistage hybrid framework using the measured pseudo-rapidity distribution of charged particles and rapidity distribution of net protons for central Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=7.7,19.6,62.4,200$ GeV. We then study the thermodynamic properties of the nuclear matter along the beam direction, and the phase diagram regions probed by the hadronization process near the chemical freeze-out. Using the rapidity-dependent thermal yields of identified particles with full rapidity coverage from the hybrid framework, we apply different scenarios of the statistical thermal model to extract the thermodynamic parameters at the freeze-out, with the known system properties from the hybrid model as a closure test. We find significant theoretical uncertainties in the thermal models when applied to regions away from midrapidity. We also propose a thermal model inspired by the hybrid approach that includes thermal smearing and longitudinal flow for the nuclear matter created at low beam energies.

    ↳ nucl-thhep-phnucl-exPRC(2024)·27 citations
11. 11*

    Modular J-PET with Improved o-Ps Detection Efficiency for CPT Tests

    Neha Chug🇵🇱 · Aleksander Gajos🇵🇱

    J-PET is a photon detector built of plastic scintillators, which already has been commissioned for CPT studies in the decays of positronium. In the first experiment, J-PET has achieved a sensitivity to CPT violation at a level of 10^{-4}, and now it aims to reach a level of 10^{-5}. This will be done by enhancing the three-photon registration efficiency for ortho-positronium decays using a new layer of densely packed plastic scintillators termed Modular J-PET. We present the simulation studies performed for different experimental detection setups to be used for the next CPT test with the Modular J-PET detector.

    ↳ hep-phhep-exnucl-exphysics.ins-det2 citations
12. 12*

    Decoding the flow evolution in Au+Au reactions at $1.23A$ GeV using hadron flow correlations and dileptons

    Tom Reichert🇩🇪 · Oleh Savchuk🇺🇸 · Apiwit Kittiratpattana🇩🇪 · Pengcheng Li🇨🇳 · Jan Steinheimer🇩🇪 · Mark Gorenstein🇺🇦 · Marcus Bleicher🇩🇪

    We investigate the development of the directed, $v_1$, and elliptic flow, $v_2$, in heavy ion collisions in mid-central Au+Au reactions at $E_{\mathrm{lab}}=1.23A$ GeV. We demonstrate that the elliptic flow of hot and dense matter is initially positive ($v_2>0$) due to the early pressure gradient. This positive $v_2$ transfers its momentum to the spectators, which leads to the creation of the directed flow $v_1$. In turn, the spectator shadowing of the in-plane expansion leads to a preferred decoupling of hadrons in the out-of-plane direction and results in a negative $v_2$ for the observable final state hadrons. We propose a measurement of $v_1-v_2$ flow correlations and of the elliptic flow of dileptons as methods to pin down this evolution pattern. The elliptic flow of the dileptons allows then to determine the early-state EoS more precisely, because it avoids the strong modifications of the momentum distribution due to shadowing seen in the protons. This opens the unique opportunity for the HADES and CBM collaborations to measure the Equation-of-State directly at 2-3 times nuclear saturation density.

    ↳ nucl-thnucl-exPLB(2023)·19 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.