Thu·Feb 16, 2023Thursday·February 16, 2023

1. 01*

   Comment on Transverse Charge Density and the Radius of the Proton

   Benjamin Boone🇺🇸 · Michael Chen🇺🇸 · Kevin Sturm🇺🇸 · Justin Yoo🇺🇸 · Douglas Higinbotham🇺🇸

   The charge radius of the proton is typically determined from electron-proton scattering by extracting the proton's electric form factor and then making use of the derivative of that form factor at zero four-momentum transfer. Unfortunately, experimentally, one cannot measure to zero four-momentum transfer and thus extrapolation is often required. In the work of Alexander Gramolin and Rebecca Russell, they present a novel method that does not use the slope and found a radius of the proton that contradicts many other recent results. Our analysis of their paper discusses some issues with this method and we show that by simply changing the binning of the data and/or including an additional set of data the results change dramatically.

   nucl-ex2 citations
2. 02*

   First Evidence of Axial Shape Asymmetry and Configuration Coexistence in ${}^{74}$Zn: Suggestion for a Northern Extension of the $N=40$ Island of Inversion

   M. Rocchini🇨🇦 · P. E. Garrett🇨🇦 · M. Zielinska🇫🇷 · S. M. Lenzi🇮🇹 · D. D. Dao🇫🇷 · F. Nowacki🇫🇷 · V. Bildstein🇨🇦 · A. D. MacLean🇨🇦 · B. Olaizola🇨🇦 · Z. T. Ahmed🇨🇦 · C. Andreoiu🇨🇦 · A. Babu🇨🇦 and 32 other authors

   The excited states of $N=44$ ${}^{74}$Zn were investigated via $\gamma$-ray spectroscopy following ${}^{74}$Cu $\beta$ decay. By exploiting $\gamma$-$\gamma$ angular correlation analysis, the $2_2^{+}$, $3_1^{+}$, $0_2^{+}$ and $2_3^{+}$ states in ${}^{74}$Zn were firmly established. The $\gamma$-ray branching and $E2/M1$ mixing ratios for transitions de-exciting the $2_2^{+}$, $3_1^{+}$ and $2_3^{+}$ states were measured, allowing for the extraction of relative $B(E2)$ values. In particular, the $2_3^{+}\to 0_2^{+}$ and $2_3^{+}\to 4_1^{+}$ transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the $N=40$ gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize ${}^{74}$Zn in its ground state. Furthermore, an excited $K=0$ band with a significantly larger softness in its shape is identified. A shore of the $N=40$ ``island of inversion'' appears to manifest above $Z=26$, previously thought as its northern limit in the chart of the nuclides.

   nucl-exnucl-thPRL(2023)·18 citations
3. 03*

   Precise lifetime measurement of ${}_{\Lambda }^4$H hypernucleus using in-flight ${}^4$He$(K^{-},{\pi }^0{)}_{\Lambda }^4$H reaction

   T. Akaishi (1) · H. Asano (2) · X. Chen (3) · A. Clozza (4) · C. Curceanu (4) · R. Del Grande (4) · C. Guaraldo (4) · C. Han (3) · T. Hashimoto (5) · M. Iliescu (4) · K. Inoue (1) · S. Ishimoto (6) and 27 other authors

   We present a new measurement of the ${}_{\Lambda }^4$H hypernuclear lifetime using in-flight $K^{-}$ + ${}^4$He $\to$ ${}_{\Lambda }^4$H + ${\pi }^0$ reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the $\gamma$-ray energy decayed from ${\pi }^0$. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from ($K^{-}$, ${\pi }^{-}$) reaction. As the first application of this method, our result for the ${}_{\Lambda }^4$H lifetime, $\tau {(}_{\Lambda }^4\mathrm{H})=206\pm 8(stat.)\pm 12(syst.)\mathrm{ps}$, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton (${}_{\Lambda }^3$H) using the same setup in the near future.

   nucl-exPLB(2023)·3 citations
4. 04*

   Electric dipole polarizability of ${}^{40}$Ca

   R. W. Fearick (1)🇿🇦 · P. von Neumann-Cosel (2)🇩🇪 · S. Bacca (3,4)🇩🇪 · J. Birkhan (2) · F. Bonaiti (3)🇩🇪 · I. Brandherm (2) · G. Hagen (5,6)🇺🇸 · H. Matsubara (7,8)🇯🇵 · W. Nazarewicz (9)🇺🇸 · N. Pietralla (2)🇩🇪 · V. Yu. Ponomarev (2)🇩🇪 · P. -G. Reinhard (10)🇩🇪 and 5 other authors

   The electric dipole strength distribution in ${}^{40}$Ca between 5 and 25 MeV has been determined at RCNP, Osaka, from proton inelastic scattering experiments at very forward angles. Combined with total photoabsorption data at higher excitation energy, this enables an extraction of the electric dipole polarizability ${\alpha }_{\mathrm{D}}$(${}^{40}$Ca) = 1.92(17) fm${}^3$. Together with the measured ${\alpha }_{\mathrm{D}}$ in ${}^{48}$Ca, it provides a stringent test of modern theoretical approaches, including coupled cluster calculations with chiral effective field theory interactions and state-of-the art energy density functionals. The emerging picture is that for this medium-mass region dipole polarizabilities are well described theoretically, with important constraints for the neutron skin in ${}^{48}$Ca and related equation of state quantities.

   nucl-exnucl-thPRResearch(2023)·26 citations
5. 05*

   Measurement of the non-prompt D-meson fraction as a function of multiplicity in proton$-$proton collisions at $\sqrt{s}=13$ TeV

   ALICE Collaboration

   The fractions of non-prompt (i.e. originating from beauty-hadron decays) D${}^0$ and D${}^{+}$ mesons with respect to the inclusive yield are measured as a function of the charged-particle multiplicity in proton$-$proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV with the ALICE detector at the LHC. The results are reported in intervals of transverse momentum ($p_{\mathrm{T}}$) and integrated in the range $1<p_{\mathrm{T}}<24$ GeV/$c$. The fraction of non-prompt D${}^0$ and D${}^{+}$ mesons is found to increase slightly as a function of $p_{\mathrm{T}}$ in all the measured multiplicity intervals, while no significant dependence on the charged-particle multiplicity is observed. In order to investigate the production and hadronisation mechanisms of charm and beauty quarks, the results are compared to PYTHIA 8 as well as EPOS 3 and EPOS 4 Monte Carlo simulations, and to calculations based on the colour glass condensate including three-pomeron fusion.

   nucl-exhep-exJHEP(2023)·14 citations
6. 06*

   Empirical Determination of the Pion Mass Distribution

   Yin-Zhen Xu🇪🇸 · Khépani Raya🇪🇸 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇨🇳 · J. Rodríguez-Quintero🇪🇸

   Existing pion+nucleus Drell-Yan and electron+pion scattering data are used to develop ensembles of model-independent representations of the pion generalised parton distribution (GPD). Therewith, one arrives at a data-driven prediction for the pion mass distribution form factor, ${\theta }_2$. Compared with the pion elastic electromagnetic form factor, ${\theta }_2$ is harder: the ratio of the radii derived from these two form factors is $r_{\pi }^{{\theta }_2}/r_{\pi }=0.79(3)$. Our data-driven predictions for the pion GPD, related form factors and distributions should serve as valuable constraints on theories of pion structure.

   ↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2023)·24 citations
7. 07*

   Prospects for ditauonium discovery at colliders

   David d'Enterria🇨🇭 · Hua-Sheng Shao🇫🇷

   The feasibility of observing ditauonium, the bound state of two tau leptons, at $e^{+}{e}^{-}$ colliders (BES III at $\sqrt{s}=3.78$ GeV, Belle II at $\sqrt{s}=10.6$ GeV, a future super tau-charm factory (STCF) at $\sqrt{s}\approx 2m_{\tau }$, and the FCC-ee at $\sqrt{s}=91.2$ GeV) as well as in hadronic and photon-photon collisions at the LHC, is studied. Cross sections and expected yields for spin-0 para- (${\mathcal{T}}_0$) and spin-1 ortho- (${\mathcal{T}}_1$) ditauonium are presented for nine different production and decay processes. Para-ditauonium can be observed at the FCC-ee via photon fusion in its diphoton decay ($\gamma \gamma \to {\mathcal{T}}_0\to \gamma \gamma$). Ortho-ditauonium can be observed at STCF via $e^{+}{e}^{-}\to {\mathcal{T}}_1\to {\mu }^{+}{\mu }^{-}$, where a threshold scan with monochromatized beams can also provide a very precise extraction of the tau lepton mass with a $\mathcal{O}(25$ keV) uncertainty or less. Observing pp $\to {\mathcal{T}}_1({\mu }^{+}{\mu }^{-})+X$ at the LHC is possible by identifying its displaced vertex with a good control of the combinatorial dimuon background. In addition, we compute the rare decay branching fractions of ditauonium into quarkonium plus a photon.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2023)·32 citations
8. 08*

   Parton Decomposition of Nucleon Spin and Momentum: Gluons from Dressed Quarks

   Peter C. Tandy🇺🇸

   The lowest two Mellin moments of hadronic Generalized Parton Distributions are explored within a model that allows investigation of the inter-related quark and gluon contributions. For light quarks their dynamical connection is strong due to quark dressing. Our principal focus is the angular momentum $J$ of the nucleon. This work employs and extends dynamical insights obtained from our recent model results for quark and gluon momentum fractions $⟨x{⟩}_{q/g}$ in both pion and nucleon. The employed model is based on the Rainbow-Ladder truncation of the Dyson-Schwinger equations of QCD. The special case of a 1-loop treatment of a single hadronic quark is used to motivate several insights and obtain initial estimates such as the Wilson line correction to the established Landau gauge model ($-7\%$ for both $J_{\mathrm{q}}$ and $⟨x{⟩}_{\mathrm{q}}$), and the "binding gluon" contribution to $⟨x{⟩}_{\mathrm{g}}$ ($\le 10\%$). We obtain the proton $J$ within 1\% after inclusion of the pion cloud mechanism to produce the sea. The gluon second Mellin moments of the proton reflect similar dynamics; ($⟨x{⟩}_{\mathrm{g}}$, $J_{\mathrm{g}}$) are (26\% , 24\%) at model scale, and (40\%, 38\%) at $2$ GeV. We also find that $J_{\mathrm{tot}}$ is shared almost equally between the total orbital and total intrinsic spin contributions.

   ↳ hep-phhep-latnucl-exnucl-thPLB(2023)·5 citations
9. 09*

   Systematic shell-model study of ${}^{98-130}$Cd isotopes and $8^{+}$ isomeric states

   Deepak Patel🇮🇳 · Praveen C. Srivastava🇮🇳 · Noritaka Shimizu🇯🇵

   We present systematic shell-model studies of even-even ${}^{98-130}$Cd isotopes using a realistic effective shell-model interaction derived from the G-matrix approach with an inert core ${}^{88}$Sr. Our calculated low-lying excited energy spectra and electromagnetic properties are compared with the experimental data. On the basis of recently available experimental data, we predict spins and parities corresponding to unconfirmed states. We also discuss the properties of $8^{+}$ isomeric states in ${}^{98-104,130}$Cd isotopes.

   ↳ nucl-thnucl-exNPA(2023)·4 citations
10. 10*

    Deep Learning Level-3 Electron Trigger for CLAS12

    Richard Tyson🇬🇧 · Gagik Gavalian🇺🇸 · David Ireland🇬🇧 · Bryan McKinnon🇬🇧

    Fast, efficient and accurate triggers are a critical requirement for modern high-energy physics experiments given the increasingly large quantities of data that they produce. The CEBAF Large Acceptance Spectrometer (CLAS12) employs a highly efficient electron trigger to filter the amount of recorded data by requiring at least one electron in each event, at the cost of a low purity in electron identification. Machine learning algorithms are increasingly employed for classification tasks such as particle identification due to their high accuracy and fast processing times. In this article, we show how a convolutional neural network could be deployed as a Level 3 electron trigger at CLAS12. We demonstrate that the AI trigger would achieve a significant data reduction compared to the traditional trigger, whilst preserving a 99.5\% electron identification efficiency. The AI trigger purity as a function of increased luminosity is improved relative to the traditional trigger. As a consequence, this AI trigger can achieve a data recording reduction improvement of 0.33\% per nA when compared to the traditional trigger whilst maintaining an efficiency above 99.5\%. A reduction in data output also reduces storage costs and post-processing times, which in turn reduces the time to the publication of new physics measurements.

    ↳ physics.ins-detnucl-exComput.Phys.Commun.(2023)·3 citations
11. 11*

    Impact of vorticity and viscosity on the hydrodynamic evolution of hot QCD medium

    Bhagyarathi Sahoo🇮🇳 · Captain R. Singh🇮🇳 · Dushmanta Sahu🇮🇳 · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳

    The strongly interacting transient state of quark-gluon plasma (QGP) medium created in ultra-relativistic collisions survives for a duration of a few fm/c. The spacetime evolution of QGP crucially depends on the equation of state (EoS), vorticity, viscosity, and external magnetic field. In the present study, we obtain the lifetime of a vortical QGP fluid within the ambit of relativistic second-order viscous hydrodynamics. We observe that the coupling of vorticity and viscosity significantly increases the lifetime of vortical QGP. The inclusion of a static magnetic field, vorticity, and viscosity makes the evolution slower. However, the static magnetic field slightly decreases the QGP lifetime by accelerating the evolution process for a non-rotating medium. We also report the rate of change of vorticity in the QGP, which will be helpful in studying the behavior of the medium in detail.

    ↳ hep-phhep-exnucl-exnucl-thEPJC(2023)·23 citations
12. 12*

    The effect of weak magnetic photon emission from quark-gluon plasma

    Jing-An Sun🇨🇳 · Li Yan🇨🇳

    We propose a novel effect that accounts for the photon emission from a quark-gluon plasma in the presence of a weak external magnetic field. Although the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate, the induced photon spectrum can be highly azimuthally anisotropic, as a consequence of the coupled effect of the magnetic field and the longitudinal dynamics in the background medium. With respect to a realistic medium evolution containing a tilted fireball configuration, the direct photon elliptic flow from experiments is reproduced. In comparison to the experimental data of direct photon elliptic flow, in heavy-ion collisions the magnitude of the magnetic field before 1 fm/c can be extracted. For the top energy of RHIC collisions, right after the pre-equilibrium evolution, $|eB|$ is found no larger than a few percent of the pion mass square.

    ↳ nucl-thhep-phnucl-exPLB(2024)·16 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.