Wed·Feb 7, 2024Wednesday·February 7, 2024

1. 01*

   Comprehensive mass measurement study of ${}^{252}$Cf fission fragments with MRTOF-MS and detailed study of masses of neutron-rich Ce isotopes

   Sota Kimura · Michiharu Wada · Hiromitsu Haba🇯🇵 · Hironobu Ishiyama · Satoshi Ishizawa · Yuta Ito🇯🇵 · Toshitaka Niwase · Marco Rosenbusch🇩🇪 · Peter Schury · Aiko Takamine

   We report the mass measurements of neutron-rich isotopes produced via spontaneous fission of ${}^{252}$Cf using a multi-reflection time-of-flight mass spectrograph. The mass of ${}^{155}$Ce is determined experimentally for the first time. A discrepancy between the experimental and literature values was found for the mass of ${}^{127}$Sb, which was previously deduced through indirect measurements. In comparison with several theoretical predictions, both the values and the trend of the mass excesses of ${}^{152-155}$Ce cannot be consistently explained. The wide-range and simultaneous mass measurements of the multi-reflection time-of-flight mass spectrograph enable us to cross-check the existing mass data, and the conflict between the measured time-of-flight ratio and the extracted mass would imply the necessity of reexamining them.

   nucl-exPRC(2024)·12 citations
2. 02*

   Measuring jet energy loss fluctuations in the quark-gluon plasma via multiparticle correlations

   Abraham Holtermann🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Anne M. Sickles🇺🇸 · Xiaoning Wang🇺🇸

   The quark-gluon plasma (QGP) is a high temperature state of matter produced in the collisions of two nuclei at relativistic energies. The properties of this matter at short distance scales are probed using jets with high transverse momentum ($p_T$) resulting from quarks and gluons scattered with large momentum transfer in the earliest stages of the collisions. The Fourier harmonics for anisotropies in the high transverse momentum particle yield, $v_n(p_T)$, indicate the path length dependence of jet energy loss within the QGP. We present a framework to build off of measurements of jet energy loss using $v_n(p_T)$ by characterizing fluctuations in jet energy loss that are currently not constrained experimentally. In this paper, we utilize a set of multivariate moments and cumulants as new experimental observables to measure event-by-event fluctuations in the azimuthal anisotropies of rare probes, and compare them to the azimuthal anisotropies of soft particles. Ultimately, these fluctuations can be used to quantify the magnitude and fluctuations of event-by-event jet energy loss. We relate these quantities to existing multivariate cumulant observables, highlight their unique properties, and validate their sensitivities with a Monte Carlo simulation.

   ↳ hep-phnucl-exnucl-th5 citations
3. 03*

   Exploring freeze out and flow using exact solutions of conformal hydrodynamics

   Owen Bradley🇺🇸 · Christopher Plumberg🇺🇸

   Exact solutions to the equations of hydrodynamics provide valuable benchmark tests for numerical hydrodynamic codes and also provide useful insights into the nature of hydrodynamic flow. In this paper, we introduce two novel, closely related exact solutions with non-trivial rapidity dependence which are generalizations of the well-known Gubser flow solution to conformal hydrodynamics. We then use one of our solutions to explore the consequences of choosing between two different criteria for implementing the freeze out process in fluid dynamical simulations of nuclear collisions: freeze out at constant temperature vs. freeze out at constant Knudsen number. We find that, employing our exact solution, the differences between these freeze out criteria are heavily influenced by the presence of strong collective flow. Our results highlight the importance of accurately describing the freeze out process in collisions with large flow gradients, particularly in small systems.

   ↳ nucl-thhep-thnucl-exPRC(2024)·2 citations
4. 04*

   Charmed hadron chemistry and flow in heavy and light ion collisions at the LHC

   Yu-Fei Liu🇨🇳 · Wen-Jing Xing🇨🇳 · Xiang-Yu Wu🇨🇦 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳 · Shu-Qing Li🇨🇳

   We study the charmed meson and baryon production and elliptic flow in ultra-relativistic nucleus-nucleus collisions at the LHC energies. The space-time evolution of quark-gluon plasma (QGP) produced in these energetic collisions is obtained via the (3+1)-dimensional CLVisc hydrodynamics model, the heavy quark dynamics inside the QGP is simulated using an improved Langevin model that incorporates both elastic and inelastic parton energy loss processes, and the heavy quark hadronization is simulated utilizing a comprehensive coalescence-fragmentation model. Using our combined approach, we first calculate charmed hadron ratios, ${\Lambda }_c/D^0$ and $D_s/D^0$, as well as their elliptic flow ($v_2$) as a function of transverse momentum ($p_T$) for different centralities in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$~TeV. Due to strangeness enhancement and parton coalescence effects, $D_s/D^0$ and ${\Lambda }_c/D^0$ ratios increase from peripheral to central collisions, and such centrality dependence for ${\Lambda }_c/D^0$ is stronger than $D_s/D^0$. We further predict the $p_T$ and centrality dependences of charmed hadron chemistry and $v_2$ in smaller Xe+Xe, Ar+Ar and O+O collisions at the LHC energies. Strong centrality and system size dependences for ${\Lambda }_c/D^0$ and $D_s/D^0$ ratios are observed across four collision systems. As for charmed hadron flow, both system size and collision geometry are important to understand the centrality dependence of $v_2$ in different collision systems. Our study provides a significant reference for studying heavy quark evolution and hadronizaiton in large and small systems in relativistic nuclear collisions.

   ↳ hep-phnucl-exnucl-th1 citation
5. 05*

   On the non-universality of heavy quark hadronization in elementary high-energy collisions

   Yuxuan Dai🇨🇳 · Shouxing Zhao🇨🇳 · Min He🇨🇳

   It has been traditionally hypothesized that the heavy quark (charm, $c$ and bottom, $b$) fragmentation is universal across different collision systems, based on the notion that hadronization as a soft process should occur at the characteristic non-perturbative QCD scale, ${\Lambda }_{QCD}$. However, this universality hypothesis has recently been challenged by the observation that the $c$- and $b$-baryon production relative to their meson counterparts in minimum bias proton-proton ($pp$) collisions at the LHC energies is significantly enhanced as compared to the electron-positron ($e^{+}{e}^{-}$) collisions. The conception of non-universality is unambiguously reinforced by the latest measurement of the charged-particle multiplicity dependence of the $b$-baryon-to-meson yield ratio, ${\Lambda }_b/B$, by the LHCb experiment in $\sqrt{s}=13$\,TeV $pp$ collisions at the LHC, evolving continuously from the saturation value in minimum bias $pp$ collisions toward the small value in $e^{+}{e}^{-}$ collisions as the system size gradually reduces. We address the multiplicity dependence of $b$-baryon production in the canonical statistical hadronization model with input $b$-hadron spectrum augmented with many hitherto unobserved states from quark model predictions. We demonstrate that the decreasing trend of the ${\Lambda }_b/B$ toward low multiplicities can be quantitatively understood from the canonical suppression on the yield of ${\Lambda }_b$, as caused by the requirement of strict conservation of baryon number in sufficiently small systems. We have therefore proposed a plausible scenario for understanding the origin of the non-universality of heavy quark fragmentation in elementary collisions.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2024)·6 citations
6. 06*

   Inference of multi-channel r-process element enrichment in the Milky Way using binary neutron star merger observations

   Hsin-Yu Chen🇺🇸 · Philippe Landry🇨🇦 · Jocelyn S. Read🇺🇸 · Daniel M. Siegel🇨🇦

   Observations of GW170817 strongly suggest that binary neutron star (BNS) mergers produce rapid neutron-capture nucleosynthesis (r-process) elements. However, it remains an open question whether these mergers can account for all the r-process element enrichment in the Milky Way's history. Here, we constrain the contributions of the BNS channel using astrophysical neutron star observations. The rate and mass distributions are constrained by LIGO/Virgo/Kagra through the latest catalog GWTC-3, the neutron star equation of state by gravitational-wave, radio, and X-ray observations, and the delay time distribution by short gamma-ray burst (GRB) host galaxy associations. We present a Bayesian framework to consistently combine these lines of observations with abundance data to quantify the contribution and uncertainties of single and multiple astrophysical enrichment sources. Whereas we obtain a distribution of per-event BNS r-process element yields consistent with geophysical and astrophysical abundance constraints, BNS-only enrichment scenarios are inconsistent with the observed r-process abundance trend of disk stars in the Galaxy. Using stellar abundance observations instead of the short GRB constraints, we infer a shorter delay time distribution with power-law index $\alpha \le -2.0$ and minimum delay time $t_{\min }\le 40$ Myr at 90\% confidence. Such delay times are in tension with those predicted by standard BNS formation models. Alternatively, we confirm that a two-channel scenario, in which the second channel tracks the star formation history without significant delay, can account for both Galactic stellar and short GRB observations. We show that 45--90\% of the r-process abundance in the Milky Way today was produced by a star-formation-tracking channel, rather than BNS mergers with significant delay times.

   ↳ astro-ph.HEgr-qcnucl-exApJ(2025)·18 citations
7. 07*

   Energetic particle contamination in STIX during Solar Orbiter's passage through Earth's radiation belts and an interplanetary shock

   Hannah Collier🇩🇪 · Olivier Limousin🇫🇷 · Hualin Xiao🇩🇪 · Arnaud Claret🇫🇷 · Frederic Schuller🇩🇪 · Nina Dresing🇫🇮 · Saku Valkila🇫🇮 · Francisco Espinosa Lara🇪🇸 · Annamaria Fedeli🇫🇮 · Simon Foucambert🇫🇷 · Säm Krucker🇩🇪

   The Spectrometer/Telescope for Imaging X-rays (STIX) is a hard X-ray imaging spectrometer on board the ESA and NASA heliospheric mission Solar Orbiter. STIX has been operational for three years and has observed X-ray emission from ~35,000 solar flares. Throughout its lifetime, Solar Orbiter has been frequently struck by a high flux of energetic particles usually of flare origin, or from coronal mass ejection shocks. These Solar Energetic Particles (SEPs) are detected on board by the purpose-built energetic particle detector instrument suite. During SEP events, the X-ray signal is also contaminated in STIX. This work investigates the effect of these particles on the STIX instrument for two events. The first event occurred during an interplanetary shock crossing and the second event occurred when Solar Orbiter passed through Earth's radiation belts while performing a gravity assist maneuver. The induced spectra consist of tungsten fluorescence emission lines and secondary Bremsstrahlung emission produced by incident particles interacting with spacecraft components. For these two events, we identify > 100 keV electrons as significant contributors to the contamination via Bremsstrahlung emission and tungsten fluorescence.

   ↳ astro-ph.SRnucl-exphysics.space-phIEEE Trans.Nucl.Sci.(2024)·2 citations
8. 08*

   On the calculation and use of effective single-particle energies. The example of the neutron $1d_{3/2}$-$1d_{5/2}$ splitting along $\text{N}=20$ isotones

   Vittorio Somà🇫🇷 · Thomas Duguet🇫🇷

   The rich phenomenology of quantum many-body systems such as atomic nuclei is complex to interpret. Often, the behaviour (e.g. evolution with the number of constituents) of measurable/observable quantities such as binding or excitation energies can be best understood on the basis of a simplified picture involving auxiliary quantities that are not observable, i.e. whose values vary with parameters that are internal to the theoretical construction (contrarily to measurable/observable quantities). While being useful, the simplified interpretation is thus theoretical-scheme-dependent. This applies, in particular, to the so-called single-nucleon shell structure based on auxiliary effective single-particle energies (ESPEs). In this context, the present work aims at (i) recalling the way to compute ESPEs out of solutions of many-body Schrödinger's equation, (ii) illustrating the use of ESPEs within the frame of state-of-the-art ab initio calculations to interpret the outcome of a recent nuclear experiment and (iii) demonstrating the impact of several alterations to the computation of ESPEs. While the chosen alterations constitute approximations within the ab initio scheme, they are built-in when employing other theoretical constructs at play in nuclear physics. The present considerations are thus meant to empirically illustrate variations that can be expected between ESPEs computed within different (equally valid) theoretical schemes.

   ↳ nucl-thnucl-exPhil.Trans.A.Math.Phys.Eng.Sci.(2024)·4 citations
9. 09*

   Nuclear Isomers at the Extremes of their Properties

   Bhoomika Maheshwari🇫🇷 · Ashok Kumar Jain

   The longer-lived excited nuclear states, referred as nuclear isomers, exist due to the hindered decays owing to their peculiar nucleonic structural surroundings. Some of these conditions, being exceptionally rare and limited to achieve, elevate certain isomers to the status of extreme and unusual isomers among their kin. For example, the $E5$ coupling of single-particle orbitals is rare and so are $E5$ decaying isomers. This review delves into some of such remarkable isomers scattered across the nuclear landscape while highlighting the possibilities to find more of them. Unique properties of some of them, harbor the potential for transformative applications in medicine and energy. An exciting example is that of the lowest energy isomer known so far in ${}^{229}$Th, which may help realize the dream of an ultra-precise nuclear clock in the coming decade. These isomers also offer an insight into the extremes of nuclear structure associated with them, which leads to their unusual status in energy, half-life, spin etc. The review attempts to highlight isomers with high-multipolarities, high-spins, high-energies, longest half-lives, extremely low energy, etc. A lack of theoretical understanding of the decay rates, half-lives and moments of these isomers is also pointed out.

   ↳ nucl-thnucl-exEur.Phys.J.ST(2024)·2 citations
10. 10*

    From existing and new nuclear and astrophysical constraints to stringent limits on the equation of state of neutron-rich dense matter

    Hauke Koehn🇩🇪 · Henrik Rose🇩🇪 · Peter T. H. Pang🇳🇱 · Rahul Somasundaram🇺🇸 · Brendan T. Reed🇺🇸 · Ingo Tews🇺🇸 · Adrian Abac🇩🇪 · Oleg Komoltsev🇳🇴 · Nina Kunert🇩🇪 · Aleksi Kurkela🇳🇴 · Michael W. Coughlin🇺🇸 · Brian F. Healy🇺🇸 · Tim Dietrich🇩🇪

    Through continuous progress in nuclear theory and experiment and an increasing number of neutron-star observations, a multitude of information about the equation of state (EOS) for matter at extreme densities is available. To constrain the EOS across its entire density range, this information needs to be combined consistently. However, the impact and model-dependency of individual observations vary. We present a broad compendium of different constraints and apply them individually to a large set of EOS candidates within a Bayesian framework. Specifically, we explore different ways how chiral effective field theory and perturbative quantum chromodynamics can be used to place a likelihood on EOS candidates. We also investigate the impact of nuclear experimental constraints, as well as different radio and X-ray observations of neutron star (NS) masses and radii. This is augmented by reanalyses of the existing data from BNS coalescences, in particular of GW170817, with improved models for the tidal waveform and kilonova light curves, which we also utilize to construct a tight upper limit of 2.39M${}_{\odot }$ on the TOV mass based on GW170817's remnant. Our diverse set of constraints is eventually combined to obtain stringent limits on NS properties. We organize the combination in a way to distinguish between constraints where the systematic uncertainties are deemed small and those that rely on less conservative assumptions. For the former, we find the radius of the canonical 1.4M${}_{\odot }$ neutron star to be $R_{1.4}=12.26_{-0.91}^{+0.80}$km and the TOV mass at $M_{\mathrm{TOV}}=2.25_{-0.22}^{+0.42}$M${}_{\odot }$ (95% credibility). Including all the presented constraints yields $R_{1.4}=12.20_{-0.48}^{+0.50}$km and $M_{\mathrm{TOV}}=2.30_{-0.20}^{+0.07}$M${}_{\odot }$.

    ↳ astro-ph.HEgr-qcnucl-exnucl-thPRX(2025)·138 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.