Wed·Aug 2, 2023Wednesday·August 2, 2023

1. 01*

   Magnetic dipole operator from chiral effective field theory for many-body expansion methods

   R. Seutin🇩🇪 · O. J. Hernandez🇩🇪 · T. Miyagi🇩🇪 · S. Bacca🇩🇪 · K. Hebeler🇩🇪 · S. König🇺🇸 · A. Schwenk🇩🇪

   Many-body approaches for atomic nuclei generally rely on a basis expansion of the nuclear states, interactions, and current operators. In this work, we derive the representation of the magnetic dipole operator in plane-wave and harmonic-oscillator basis states, as needed for Faddeev calculations of few-body systems or many-body calculations within, e.g., the no-core shell model, the in-medium renormalization group, coupled-cluster theory, or the nuclear shell model. We focus in particular on the next-to-leading-order two-body contributions derived from chiral effective field theory. We provide detailed benchmarks and also comparisons with quantum Monte Carlo results for three-body systems. The derived operator matrix elements represent the basic input for studying magnetic properties of atomic nuclei based on chiral effective field theory.

   ↳ nucl-thnucl-exPRC(2023)·13 citations
2. 02*

   Correlations between charge radii differences of mirror nuclei and stellar observables

   P. Bano · S. P. Pattnaik · M. Centelles🇪🇸 · X. Viñas🇪🇸 · T. R. Routray🇮🇳

   The correlation between the charge radii differences in mirror nuclei pairs and the neutron skin thickness has been studied with the so-called finite range simple effective interaction over a wide mass region. The so far precisely measured charge radii difference data within their experimental uncertainty ranges in the 34Ar-34S, 36Ca-36S, 38Ca-38Ar, and 54Ni-54Fe mirror pairs are used to ascertain an upper limit for the slope parameter of the nuclear symmetry energy L $\approx$ 100 MeV. This limiting value of L is found to be consistent with the upper bound of the NICER PSR J0740+6620 constraint at 1$\sigma$ level for the radius R${}_{1.4}$ of 1.4 M${}_{\odot }$ neutron stars. The lower bound of the NICER R${}_{1.4}$ data constrains the lower limit of L to $\approx$ 70 MeV. Within the range for L = 70-100 MeV the tidal deformability ${\Lambda }^{1.4}$ constraint, which is extracted from the GW170817 event at 2$\sigma$ level, and the recent PREX-2 and CREX data on the neutron skin thickness are discussed.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2023)·31 citations
3. 03*

   Inclusive, prompt and non-prompt $\mathrm{J}/\psi$ identification in proton-proton collisions at the Large Hadron Collider using machine learning

   Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳

   Studies related to $\mathrm{J}/\psi$ meson, a bound state of charm and anti-charm quarks ($c\bar{c}$), in heavy-ion collisions, provide genuine testing grounds for the theory of strong interaction, quantum chromodynamics (QCD). To better understand the underlying production mechanism, cold nuclear matter effects, and influence from the quark-gluon plasma, baseline measurements are also performed in proton-proton ($pp$) and proton-nucleus ($p$--A) collisions. The inclusive $\mathrm{J}/\psi$ measurement has contributions from both prompt and non-prompt productions. The prompt $\mathrm{J}/\psi$ is produced directly from the hadronic interactions or via feed-down from directly produced higher charmonium states, whereas non-prompt $\mathrm{J}/\psi$ comes from the decay of beauty hadrons. In experiments, $\mathrm{J}/\psi$ is reconstructed through its electromagnetic decays to lepton pairs, in either $e^{+}+e^{-}$ or ${\mu }^{+}+{\mu }^{-}$ decay channels. In this work, for the first time, machine learning techniques are implemented to separate the prompt and non-prompt dimuon pairs from the background to obtain a better identification of the $\mathrm{J}/\psi$ signal for different production modes. The study has been performed in $pp$ collisions at $\sqrt{s}=7$ and 13 TeV simulated using PYTHIA8. Machine learning models such as XGBoost and LightGBM are explored. The models could achieve up to 99\% prediction accuracy. The transverse momentum ($p_{\mathrm{T}}$) and rapidity ($y$) differential measurements of inclusive, prompt, and non-prompt $\mathrm{J}/\psi$, its multiplicity dependence, and the $p_{\mathrm{T}}$ dependence of fraction of non-prompt $\mathrm{J}/\psi$ ($f_{\mathrm{B}}$) are shown. These results are compared to experimental findings wherever possible.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·17 citations
4. 04*

   Energy Correlators Taking Charge

   Kyle Lee🇺🇸 · Ian Moult🇺🇸

   The confining transition from asymptotically free partons to hadrons remains one of the most mysterious aspects of Quantum Chromodynamics. With the wealth of high quality jet substructure data we can hope to gain new experimental insights into the details of its dynamics. Jet substructure has traditionally focused on correlations, $⟨\mathcal{E}(n_1)\mathcal{E}(n_2)\cdots \mathcal{E}(n_k)⟩$, in the energy flux of hadrons. However, significantly more information about the confinement transition is encoded in how energy is correlated between hadrons with different quantum numbers, for example electric charge. In this Letter we develop the field theoretic formalism to compute general correlations, $⟨{\mathcal{E}}_{R_1}(n_1){\mathcal{E}}_{R_2}(n_2)\cdots {\mathcal{E}}_{R_k}(n_k)⟩$, between the energy flux carried by hadrons with quantum numbers $R_i$, by introducing new universal non-perturbative functions, which we term joint track functions. Using this formalism we show that the strong interactions introduce enhanced small angle correlations between opposite-sign hadrons, relative to like-sign hadrons, identifiable as an enhanced scaling of $⟨{\mathcal{E}}_{+}(n_1){\mathcal{E}}_{-}(n_2)⟩$ relative to $⟨{\mathcal{E}}_{+}(n_1){\mathcal{E}}_{+}(n_2)⟩$. We are also able to compute the scaling of a $C$-odd three-point function, $⟨{\mathcal{E}}_{\mathcal{Q}}(n_1){\mathcal{E}}_{\mathcal{Q}}(n_2){\mathcal{E}}_{\mathcal{Q}}(n_3)⟩$. Our results greatly extend the class of systematically computable jet substructure observables, pushing perturbation theory deeper into the parton to hadron transition, and providing new observables to understand the dynamics of confinement.

   ↳ hep-phhep-exnucl-exnucl-th58 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.