Tue·Sep 21, 2021Tuesday·September 21, 2021

1. 01*

   $\mathcal{F}t$ values of the mirror $\beta$ transitions and the weak magnetism induced current in allowed nuclear $\beta$ decay

   N. Severijns🇧🇪 · L. Hayen🇺🇸 · V. De Leebeeck🇧🇪 · S. Vanlangendonck🇧🇪 · K. Bodek🇵🇱 · D. Rozpedzik🇵🇱 · I.S. Towner🇺🇸

   In recent years a number of correlation measurements in nuclear $\beta$ decay have been performed reaching a precision of the order of 1\% and below and it is expected that even higher precision will be reached in the near future. At these levels of precision higher-order corrections due to e.g. recoil terms induced by the strong interaction and radiative corrections cannot necessarily be neglected anymore when interpreting these results in terms of new physics or extracting a value for the $V_{ud}$ quark-mixing matrix element. We provide here an update of the $\mathcal{F}t$ values of the $T=1/2$ mirror $\beta$ decays as well as an overview of current experimental and theoretical knowledge of the most important recoil term, weak magnetism, for both the $T=1/2$ mirror $\beta$ transitions and a large set of $\beta$ decays in higher isospin multiplets. The matrix elements determining weak magnetism were calculated in the nuclear shell model and cross-checked against experimental data, showing overall good agreement. Additionally, we show that further insight can be obtained from properly deformed nuclear potentials, in particular for mirror $T=1/2$ decays.. The results provide new insights in the size of weak magnetism, extending the available information to $\beta$ transitions of nuclei with masses up to $A=$ 75. This provides important guidance for the planning and interpretation of ongoing and new precise correlation measurements in nuclear $\beta$ decay searching for new physics or to extract the $V_{ud}$ quark-mixing matrix element in mirror $\beta$ decays. This more detailed knowledge of weak magnetism can also be of interest for further theoretical work related to the reactor neutrino problem.

   nucl-exnucl-thPRC(2023)·28 citations
2. 02*

   Heavy flavor collectivity in small systems

   Georgios Konstantinos Krintiras (on behalf of the ALICE, ATLAS, and CMS Collaborations)🇺🇸

   The presence of correlations between particles significantly separated in pseudorapidity in proton-proton and proton-nucleus collisions revealed surprises in the early LHC data. Are the physical processes responsible for the observed long-range pseudorapidity correlations and their azimuthal structure the same in small collision systems as in heavy ion collisions? Whereas in the case of heavy ion collisions "flow" is interpreted as generated by initial geometric inhomogeneities, calculations indicate that initial-state momentum correlations are present and could contribute to the observed azimuthal anisotropy in small systems. Probes involving heavy quarks provide us with a unique opportunity to disentangle different quantum chromodynamics effects at the boundary between low- and high-$p_{\mathrm{T}}$ interactions, and hence shed light on the origin of flow in small collision systems. A selection of the latest measurements is presented for the flow and production of heavy flavor hadrons and their decay products.

   nucl-exPoS(2021)·0 citations
3. 03*

   Pauli radius of the proton

   Zhu-Fang Cui🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   Using a procedure based on interpolation via continued fractions supplemented by statistical sampling, we analyse proton magnetic form factor data obtained via electron+proton scattering on $Q^2\in [0.027,0.55]$GeV${}^2$ with the goal of determining the proton magnetic radius. The approach avoids assumptions about the function form used for data interpolation and ensuing extrapolation onto $Q^2\simeq 0$ for extraction of the form factor slope. In this way, we find $r_M=0.817(27)$fm. Regarding the difference between proton electric and magnetic radii calculated in this way, extant data are seen to be compatible with the possibility that the slopes of the proton Dirac and Pauli form factors, $F_{1,2}(Q^2)$, are not truly independent observables; to wit, the difference $F_1^{\prime }(0)-F_2^{\prime }(0)/{\kappa }_p=[1+{\kappa }_p]/[4m_p^2]$, viz. the proton Foldy term.

   ↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2021)·11 citations
4. 04*

   Soft QCD results from ALICE

   Sushanta Tripathy (for the ALICE collaboration)🇮🇹

   High-energy hadronic collisions are dominated by soft interactions with low momentum transfers. The description of these processes typically relies on phenomenological models. The soft QCD measurements, such as characterisation of the underlying event (UE) and study of light flavored hadrons, provide important constraints on the model parameters. They also provide additional insights into the recent measurements at the LHC where features normally attributed to QGP formation in Pb-Pb collisions have been observed even in pp and p-Pb collisions. Here, we present an analysis based on UE measurements applied to p-Pb collisions for the first time at the LHC to test the similarities between pp and p-Pb collisions. Furthermore, it is shown that the UE at midrapidity is correlated with the energy measured at forward rapidity by ALICE zero degree calorimeters (ZDC). Using ZDC, a multi-differential study is shown to disentangle initial and final-state effects on strange hadron production in pp collisions.

   ↳ hep-exnucl-exPoS(2021)·0 citations
5. 05*

   Angular correlations of heavy-flavour hadron decay electrons and charged particles in pp collisions at $\sqrt{s}$ = 5.02 TeV with ALICE at the LHC

   Ravindra Singh (for the ALICE Collaboration)🇮🇳

   Two-particle azimuthal correlations of electrons from heavy-flavour hadron decays with charged particles can give insight into the properties of heavy-quark production and hadronization into heavy-flavour jets.\\ In this contribution, the ALICE results measured in pp collisions at 5.02 TeV, collected in the LHC Run 2, are presented. The yields of charged particles in the near and away-side correlation peaks and the peak width are compared with PYTHIA calculations.

   ↳ hep-exnucl-exPoS(2021)·3 citations
6. 06*

   Heavy-flavour hadron production

   Mattia Faggin🇮🇹

   The conventional description of heavy-flavour hadron production in pp collisions is based on a factorisation approach, assuming universal fragmentation functions among collision systems. Recent results on heavy-flavour baryon measurements from the LHC experiments show tensions with model calculations based on this approach and employing fragmentation functions constrained from ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and ${\mathrm{e}}^{-}\mathrm{p}$ collision experiments. In this contribution, the most recent results from ALICE, ATLAS, CMS and LHCb experiments on the heavy-flavour hadron production in pp collisions at the TeV scale are reported. The comparison with the theoretical predictions that address the baryon enhancement in hadronic collisions at the LHC is also discussed.

   ↳ hep-exnucl-exPoS(2021)·3 citations
7. 07*

   Dipole excitation of ${}^6$Li and ${}^9$Be studied with an extended quantum molecular dynamics model

   Bo-Song Huang🇨🇳 · Yu-Gang Ma🇨🇳

   The $\alpha$ (${}^4$He) - clustering structure is a common phenomenon in light nuclei due to the decreasing contribution of mean field in few-body system. In this work we presented calculations of giant dipole resonance (GDR) excitations for two non $\alpha$-conjugate light nuclei, namely ${}^6$Li and ${}^9$Be, within a framework of an extended quantum molecular dynamics model. For ${}^6$Li, we investigated the GDR spectra from the two-body clustering structure with $\alpha$ + deuteron as well as the three-body structure with $\alpha$ + $n$ + $p$, and found that the major $\alpha$-clustering contribution on the GDR peak is located at around 31 MeV, while the resonance contributions between clusters, namely $\alpha$ and deuteron or ($n$ + $p$), are located on the lower energy side, which can be regarded as pygmy dipole resonance (PDR). For ${}^9$Be, a mixture configuration contribution for the Chain-like structure and Borromean-like structure of the $\alpha$ + n + $\alpha$ configuration can somehow explain its GDR results.

   ↳ nucl-thnucl-exPRC(2021)·26 citations
8. 08*

   Systematic Nuclear Uncertainties in the Hypertriton System

   Thiri Yadanar Htun🇹🇭 · Daniel Gazda🇨🇿 · Christian Forssén🇸🇪 · Yupeng Yan🇹🇭

   The hypertriton bound state is relevant for inference of knowledge about the hyperon-nucleon (YN) interaction. In this work we compute the binding energy of the hypertriton using the ab initio hypernuclear no-core shell model (NCSM) with realistic interactions derived from chiral effective field theory. In particular, we employ a large family of nucleon-nucleon interactions with the aim to quantify the theoretical precision of predicted hypernuclear observables arising from nuclear-physics uncertainties. The three-body calculations are performed in a relative Jacobi-coordinate harmonic oscillator basis and we implement infrared correction formulas to extrapolate the NCSM results to infinite model space. We find that the spread of the predicted hypertriton binding energy, attributed to the nuclear-interaction model uncertainty, is about 100 keV. In conclusion, the sensitivity of the hypertriton binding energy to nuclear-physics uncertainties is of the same order of magnitude as experimental uncertainties such that this bound-state observable can be used in the calibration procedure to constrain the YN interactions.

   ↳ nucl-thnucl-exFew Body Syst.(2021)·9 citations
9. 09*

   Chiral Effective Field Theory after Thirty Years: Nuclear Lattice Simulations

   Dean Lee🇺🇸

   The introduction of chiral effective field theory by Steven Weinberg three decades ago has had a profound and lasting impact on nuclear physics. This brief review explores the impact of Weinberg's work on the field of nuclear lattice simulations. Rather than a summary of technical details, an effort is made to present the conceptual advances that made much of the recent progress possible.

   ↳ nucl-thhep-latnucl-exFew Body Syst.(2021)·3 citations
10. 10*

    Novel Bayesian neural network based approach for nuclear charge radii

    Xiao-Xu Dong · Rong An · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳

    Charge radius is one of the most fundamental properties of a nucleus. However, a precise description of the evolution of charge radii along an isotopic chain is highly nontrivial, as reinforced by recent experimental measurements. In this paper, we propose a novel approach which combines a three-parameter formula and a Bayesian neural network. We find that the novel approach can describe the charge radii of all $A\ge 40$ and $Z\ge 20$ nuclei with a root-mean-square deviation about 0.015 fm. In particular, the charge radii of the calcium isotopic chain are reproduced very well, including the parabolic behavior and strong odd-even staggerings. We further test the approach for the potassium isotopes and show that it can describe well the experimental data within uncertainties.

    ↳ nucl-thnucl-exPRC(2022)·76 citations
11. 11*

    Green-Kubo formula for Boltzmann and Fermi-Dirac statistics

    X. G. Deng🇨🇳 · Y. G. Ma🇨🇳 · Y. X. Zhang

    Shear viscosity of nuclear matter is extracted via the Green-Kubo formula and the Gaussian thermostated SLLOD algorithm (the shear rate method) in a periodic box by using an improved quantum molecular dynamic (ImQMD) model without mean field, also it is calculated by a Boltzmann-type equation. Here a new form of the Green-Kubo formula is put forward in the present work. For classical limit at nuclear matter densities of $0.4{\rho }_0$ and $1.0{\rho }_0$, shear viscosity by the traditional and new form of the Green-Kubo formula as well as the SLLOD algorithm are coincident with each other. However, for non-classical limit, shear viscosity by the traditional form of the Green-Kubo formula is higher than those obtained by the new form of the Green-Kubo formula as well as the SLLOD algorithm especially in low temperature region. In addition, shear viscosity from the Boltzmann-type equation is found to be less than that by the Green-Kubo method or the SLLOD algorithm for both classical and non-classical limits.

    ↳ nucl-thnucl-exEPJA(2021)·4 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.