Tue·Sep 10, 2024Tuesday·September 10, 2024

1. 01*

   Measurement of the Free Neutron Lifetime in a Magneto-Gravitational Trap with In Situ Detection

   R. Musedinovic (1)🇺🇸 · L. S. Blokland (2)🇺🇸 · C. B. Cude-Woods (3)🇺🇸 · M. Singh (3)🇺🇸 · M. A. Blatnik (3 and 4)🇺🇸 · N. Callahan (5)🇺🇸 · J. H. Choi (1)🇺🇸 · S. Clayton (3)🇺🇸 · B. W. Filippone (4)🇺🇸 · W. R. Fox (2)🇺🇸 · E. Fries (4)🇺🇸 · P. Geltenbort (6)🇫🇷 and 23 other authors

   Here we publish three years of data for the UCNtau experiment performed at the Los Alamos Ultra Cold Neutron Facility at the Los Alamos Neutron Science Center. These data are in addition to our previously published data. Our goals in this paper are to better understand and quantify systematic uncertainties and to improve the lifetime statistical precision. We report a measured value for these runs from 2020-2022 for the neutron lifetime of 877.94+/-0.37 s; when all the data from UCNtau are averaged we report an updated value for the lifetime of 877.82+/-0.22 (statistical)+0.20-0.17 (systematic) s. We utilized improved monitor detectors, reduced our correction due to UCN upscattering on ambient gas, and employed four different main UCN detector geometries both to reduce the correction required for rate dependence and explore potential contributions due to phase space evolution.

   nucl-exPRC(2025)·15 citations
2. 02*

   Weak decays in superheavy nuclei

   A. Ravlić🇺🇸 · W. Nazarewicz🇺🇸

   Superheavy nuclei represent the heaviest atoms and nuclides known at the limit of mass and charge. The observed superheavy nuclei are all proton-rich; they decay primarily by emitting $\alpha$ particles and fission, with a possible small electron capture (EC) branch. Due to the huge atomic numbers and associated relativistic effects, EC-decays of superheavy systems are expected to differ from what is known in lighter nuclei. In this paper, using the quantified relativistic nuclear density functional theory and the quasiparticle random-phase approximation with the interaction optimized to experimental ${\beta }^{-}$-decay half-lives and Gamow-Teller resonance energies, we study the EC/${\beta }^{\pm }$-decays in $Z=101-118$ nuclei. Both allowed ($1^{+}$) and first-forbidden ($0^{-},1^{-}$ and $2^{-}$) transitions are considered. We show that the first-forbidden $1^{-}$ transitions dominate the decay rates in almost all studied nuclei. For proton-rich nuclei, EC dominates over ${\beta }^{+}$ decay. We identify 44 nuclei with EC/${\beta }^{+}$ branching ratio larger than 5\%, indicating a possible competition with $\alpha$-decay and spontaneous fission channels.

   ↳ nucl-thnucl-exPRC(2025)·7 citations
3. 03*

   Effect of vector meson spin coherence on the measurements of chiral magnetic effect in heavy-ion collisions

   Zhiyi Wang🇨🇳 · Jinhui Chen🇨🇳 · Diyu Shen🇨🇳 · Aihong Tang🇺🇸 · Gang Wang🇺🇸

   The chiral magnetic effect (CME) in heavy-ion collisions reflects the local violation of $\mathcal{P}$ and $\mathcal{C}\mathcal{P}$ symmetries in strong interactions and manifests as electric charge separation along the direction of the magnetic field created by the wounded nuclei. The experimental observables for the CME, such as the ${\gamma }_{112}$ correlator, the $R_{{\Psi }_2}(\Delta S)$ correlator, and the signed balance functions, however, are also subject to non-CME backgrounds, including those from resonance decays. A previous study showed that the CME observables are affected by the diagonal component of the spin density matrix, the ${\rho }_{00}$ for vector mesons. In this work, we study the contributions from the other elements of the spin density matrix using a toy model and a multiphase transport model. We find that the real part of the ${\rho }_{1-1}$ component, $\mathrm{Re}{\rho }_{1-1}$, affects the CME observables in a manner opposite to that of the ${\rho }_{00}$. All three aforementioned CME observables show a linear dependence on $\mathrm{Re}{\rho }_{1-1}$ in the model calculations, supporting our analytical derivations. The rest elements of the spin density matrix do not contribute to the CME observables. The off-diagonal terms in the spin density matrix indicate spin coherence and may be nonzero in heavy-ion collisions due to local spin polarization or spin-spin correlations. Thus, $\mathrm{Re}{\rho }_{1-1}$, along with ${\rho }_{00}$, could play a significant role in interpreting measurements in search of the CME.

   ↳ nucl-thnucl-exPRC(2025)·5 citations
4. 04*

   Partial-wave analysis to determine the spin of $\Xi (1690{)}^{-}$ and $\Xi (1820{)}^{-}$ produced in $\overline{p}p$ annihilation

   Deepak Pachattu🇮🇳

   Recently [arXiv:2201.03852v2] the PANDA collaboration studied the feasibility of determining the spin and parity of the $\Xi (1690{)}^{-}$and $\Xi (1820{)}^{-}$ resonances in the $\Lambda K^{-}$ system produced in $\bar{p}p$ collisions via the reaction channel $\overline{p}p\to {\bar{\Xi }}^{+}\Lambda K^{-}$. This contribution aims to study these reactions using a model-independent irreducible tensor formalism developed earlier. This study leads us to identify the partial-wave amplitude, which would be zero if $\Xi (1690{)}^{-}$ or $\Xi (1820{)}^{-}$ had spin-1/2, provided these resonances are produced at threshold (s-wave production).

   ↳ nucl-thhep-exhep-phhep-th+1EPJA(2025)·0 citations
5. 05*

   Strong decays of $a_0$, $f_0$, $f_2$, and $K_2^{\ast }$ resonances as dynamically generated states of two vector mesons

   Qing-Hua Shen🇨🇳 · Li-Sheng Geng🇨🇳 · Ju-Jun Xie🇨🇳

   The two-body strong decays of the $f_0(1500)$, $f_0(1710)$, $a_0(1710)$, $f_2(1270)$, $f_2^{\prime }(1525)$, and $K_2^{\ast }(1430)$ resonances are investigated, assuming them as dynamically generated states of two vector mesons via $s$-wave interactions. The partial decay widths of all the possible two-body pseudoscalar meson-pseudoscalar meson final states are calculated considering the triangular diagrams. It is found that the ratios of branching fractions are similar to the previous results for most channels, which were obtained by using the real-axis method and considering the box diagrams. However, there are also differences. In addition, our focus is on the partial decay widths. More precise experimental measurements are needed to test the model calculations and determine the nature of these scalar and tensor mesons. It is anticipated that the BES\uppercase\expandafter{\romannumeral3}, Belle\uppercase\expandafter{\romannumeral2} and LHCb collaborations will conduct these measurements in the future.

   ↳ hep-phhep-exhep-thnucl-ex+1EPJA(2025)·5 citations
6. 06*

   Probing strangeness with event topology classifiers in pp collisions at energies available at the CERN Large Hadron Collider with the rope hadronization mechanism in PYTHIA

   Suraj Prasad🇮🇳 · Bhagyarathi Sahoo🇮🇳 · Sushanta Tripathy🇨🇭 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳

   In relativistic heavy-ion collisions, the formation of a deconfined and thermalized state of partons, known as quark-gluon plasma (QGP), leads to enhanced production of strange hadrons in contrast to proton-proton (pp) collisions, which are taken as baseline. This observation is known as strangeness enhancement in heavy-ion collisions and is considered one of the important signatures that can signify the formation of QGP. However, in addition to strangeness enhancement, recent measurements hint at observing several heavy-ion-like features in high multiplicity pp collisions at energies available at the CERN Large Hadron Collider. Alternatively, event shape observables, such as transverse spherocity, transverse sphericity, charged particle flattenicity, and relative transverse activity classifiers, can fundamentally separate hard interaction-dominated jetty events from soft isotropic events. These features of event shape observables can probe the observed heavy-ion-like features in pp collisions with significantly reduced selection bias and can bring all collision systems on equal footing. In this article, we present an extensive summary of the strange particle ratios to pions as a function of different event classifiers using the PYTHIA~8 model with color reconnection and rope hadronization mechanisms to understand the microscopic origin of strangeness enhancement in pp collisions and also prescribe the applicability of these event classifiers in the context of strangeness enhancement. Charged particle flattenicity is found to be most suited for the study of strangeness enhancement, and it shows a quantitative enhancement similar to that seen for the analysis based on the number of multi-parton interactions.

   ↳ hep-phhep-exhep-thnucl-ex+1PRC(2025)·14 citations
7. 07*

   A simple explanation of the absence of the spherical nuclei with the hidden-color states

   Tao Wang🇨🇳

   Inspired by the EMC effect, the Cd puzzle and the SU3-IBM, a hypothesis can be given for a nucleus, that only the nucleus itself is a trivial (0,0) representation of the SU(3) group, which leads to the simple conclusion that spherical nucleus does not exist and the spherical mean field is not allowed. The key conclusion is that the whole nucleus should have many hidden-color states, and the quark-gluon degrees of freedom are required even at the low-energy excitation of the nucleus.

   ↳ nucl-thhep-phnucl-ex0 citations
8. 08*

   Exclusive vector-quarkonium photoproduction at NLO in alpha_s in collinear factorisation with evolution of the generalised parton distributions and high-energy resummation

   C.A. Flett🇫🇷 · J.P. Lansberg🇫🇷 · S. Nabeebaccus🇫🇷 · M. Nefedov🇫🇷 · P. Sznajder🇵🇱 · J. Wagner🇵🇱

   We perform the first complete one-loop study of exclusive photoproduction of vector quarkonia off protons in Collinear Factorisation (CF) including the scale evolution of the Generalised Parton Distributions (GPDs). We confirm the perturbative instability of the cross section at high photon-proton-collision energies (W_gamma+p) at Next-to-Leading Order (NLO) in alpha_s and solve this issue by resumming higher-order QCD corrections, which are enhanced by a logarithm of the parton energies, using High-Energy Factorisation (HEF) in the Doubly-Logarithmic Approximation (DLA) matched to CF. Our NLO CF + DLA HEF results are in agreement with the latest HERA data, show a smaller sensitivity to the factorisation and renormalisation scales compared to Born-order results. Quark-induced channels via interference with gluon ones are found to contribute at most 20% of the cross section for W_gamma+p > 100 GeV. Our results also show that such exclusive cross sections cannot be accurately obtained from the square of usual Parton Distribution Functions (PDFs) and clearly illustrate the importance of quarkonium exclusive photoproduction to advance our understanding of the 3D content of the nucleon in terms of gluons. Our work provides an important step towards a correct interpretation of present and future experimental data collected at HERA, the EIC, the LHC and future experiments.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2024)·28 citations
9. 09*

   Factorization for jet production in heavy-ion collisions

   Yacine Mehtar-Tani🇺🇸 · Felix Ringer🇺🇸 · Balbeer Singh🇺🇸 · Varun Vaidya🇺🇸

   We develop an Effective Field Theory approach for jet observables in heavy-ion collisions, where the jet is treated as an open quantum system interacting with a hot and dense QCD medium. Within this framework, we derive a novel factorization formula for inclusive jet production, expressed as a series expansion with an increasing number of radiating subjet functions that encode forward scattering with the Quark-Gluon Plasma, convolved with perturbative matching coefficients. This work provides a systematic framework for computing jet observables at higher order and understanding their non-perturbative aspects, paving the way for future applications in heavy-ion phenomenology.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2025)·18 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.