Fri·Sep 13, 2024Friday·September 13, 2024

1. 01*

   Critical evaluation of reference charge radii and applications in mirror nuclei

   Ben Ohayon🇮🇱

   I present a critical review of absolute root-mean-square charge radii of stable nuclei from $Z=3$ to $Z=32$, which includes a previously overlooked uncertainty in the combined analysis of muonic x-ray and electron scattering experiments. From these \textit{reference radii} and isotope shift measurements, I obtain those of 12 mirror pairs with a traceable and realistic uncertainty budget. The difference in radii between mirror nuclei is found to be proportional to the isospin asymmetry, confirming recent calculations by Novario \emph{et al}~[PRL~130, 032501]. Assuming that this linear relation holds across the nuclear chart, the fitted proportionality constant, combined with the revised known radii, predicts the radii of 73 previously unknown mirror partners. These are useful e.g., for benchmarking atomic and nuclear theory, calibrating entire chains, and as an input to nuclear beta-decay calculations. The radii of $(T=1,T_z=0)$ nuclei are interpolated assuming negligible isospin symmetry breaking. This completes a model-independent, high-precision extraction of the charge and weak radii of all nuclei involved in the testing of the unitarity of the CKM matrix.

   nucl-exnucl-thphysics.atom-phAtom.Data Nucl.Data Tabl.(2025)·25 citations
2. 02*

   Color transparency in hard $pd$ collisions

   A.B. Larionov🇷🇺

   As one of the predictions of perturbative QCD, the effect of color transparency has been the focus of attention in the community studying modifications of hadrons in nuclear medium for several decades. The search for this effect in reactions involving heavy nuclei can be complicated by uncertainties in nuclear characteristics (nucleon density distributions and wave functions), which can affect the interpretation of experiments. In this work, we consider the reaction $d(p,pp)n$ at $p_{\mathrm{lab}}=15$ GeV/c caused by hard elastic $pp$ scattering, in which these uncertainties are actually reduced to the behavior of the deuteron wave function at large momenta. It is shown that for transverse momenta of the spectator neutron $\le 0.4$ GeV/c the choice of the deuteron wave function cannot affect the identification of the color transparency effect. A simple method for studying color transparency in $dd$ collisions is also suggested based on the identification of quasi-free $pd$ interactions.

   ↳ nucl-thhep-exhep-phnucl-ex0 citations
3. 03*

   Unified study of nucleon and $\Delta$ baryon spectra and their strong decays with chiral dynamics

   Hui-Hua Zhong🇨🇳 · Ming-Sheng Liu🇨🇳 · Ru-Hui Ni🇨🇳 · Mu-Yang Chen🇨🇳 · Xian-Hui Zhong · Qiang Zhao🇨🇳

   In this work we systematically study both the mass spectra and strong decays of the nucleon and $\Delta$ resonances up to the $N=2$ shell within a unified quark model framework with chiral dynamics. In this framework we achieve a good description of the strong decay properties of the well-established nucleon and $\Delta$ resonances. Meanwhile, the mass reversal between $N(1440)1/2^{+}$ as the first radial excitation state and the $1P$-wave nucleon resonances can be explained. We show that the three-body spin-orbit potential arising from the one-gluon exchange can cause a large configuration mixing between $N(1520)3/2^{-}$ and $N(1700)3/2^{-}$, and is also responsible for the large splitting between $\Delta (1600)1/2^{-}$ and $\Delta (1700)3/2^{-}$. Some of these baryon resonances turn to weakly couple to the $N\pi$, $N\eta$, $K\Lambda$, and $K\Sigma$ channels, which may answer the question why they have not been established in these channels via the $\pi N$ and $\gamma N$ scatterings. It shows that these ``missing resonances" may have large potentials to be established in the $N\pi \pi$ final state due to their large decay rates into either the $\Delta (1232)$ or $1P$-wave nucleon resonances via the pionic decays. Further experimental search for their signals in charmonium decays at BESIII is thus strongly recommended.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·20 citations
4. 04*

   First Extraction of Transverse Momentum Dependent Helicity Distributions

   Ke Yang🇨🇳 · Tianbo Liu🇨🇳 · Peng Sun🇨🇳 · Yuxiang Zhao🇨🇳 · Bo-Qiang Ma🇨🇳

   We report on the first global analysis of transverse momentum dependent helicity distributions of the proton. The analysis is performed at next-to-leading order with the evolution factor at next-to-next-to-leading-logarithmic accuracy. Nonzero signals are determined for up and down quarks and their $k_T$-integrated polarization are consistent with analyses in collinear factorization, while the distributions of other flavors are loosely constrained by existing data. With increasing transverse momentum, quarks at large $x$ become less polarized while those at small $x$ become more polarized.

   ↳ hep-phhep-exnucl-exnucl-thPRL(2025)·15 citations
5. 05*

   Converting sWeights to Probabilities with Density Ratios

   D.I. Glazier🇬🇧 · R. Tyson🇺🇸

   The use of machine learning approaches continues to have many benefits in experimental nuclear and particle physics. One common issue is generating training data which is sufficiently realistic to give reliable results. Here we advocate using real experimental data as the source of training data and demonstrate how one might subtract background contributions through the use of probabilistic weights which can be readily applied to training data. The sPlot formalism is a common tool used to isolate distributions from different sources. However, the negative sWeights produced by the sPlot technique can cause training problems and poor predictive power. This article demonstrates how density ratio estimation can be applied to convert sWeights to event probabilities, which we call drWeights. The drWeights can then be applied to produce the distributions of interest and are consistent with direct use of the sWeights. This article will also show how decision trees are particularly well suited to convert sWeights, with the benefit of fast prediction rates and adaptability to aspects of experimental data such as the data sample size and proportions of different event sources. We also show that a density ratio product approach in which the initial drWeights are reweighted by an additional converter gives substantially better results.

   ↳ physics.data-anhep-exnucl-exComput.Phys.Commun.(2026)·2 citations
6. 06*

   Ultrashort laser-induced nuclear reactions: initiating decay of helium nuclei and subsequent fusion reactions

   L. M. Kovachev · E. Iordanova · G. Yankov · I. P. Angelov

   We present a novel method to construct particle accelerators targeting light atoms and nuclei using high-power femtosecond laser pulses. Initially, we confine light atoms within the laser pulse envelope due to longitudinal polarization forces, allowing them to acquire kinetic energies of several GeV. Subsequently, an external electric field separates the nuclei at the cathode, concentrating helium nuclei in a small area. The kinetic energy of the 1.88 GeV impacts, exceeding the alpha particle binding energy (28 MeV) by two orders of magnitude, induces powerful gamma radiation and neutron emission from decay processes. This experiment marks a demonstration of a laser-induced decay method for helium nuclei for the first time. Moreover, helium isotopes or deuterium nuclei trapped on the cathode show significantly reduced Coulomb repulsion, enabling subsequent nuclear fusion reactions and substantial nuclear energy release.

   ↳ physics.opticsnucl-ex0 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.