Tue·Nov 21, 2023Tuesday·November 21, 2023

1. 01*

   Exploration of hadronization through heavy flavor production at the future Electron-Ion Collider

   Xuan Li🇺🇸

   The future Electron-Ion Collider will utilize high-luminosity high-energy electron+proton ($e+p$) and electron+nucleus ($e+A$) collisions to solve several fundamental questions in the high energy nuclear physics field. Heavy flavor products play an important role in constraining the initial-state nucleon/nucleus parton distribution functions especially in the high and low Bjorken-x ($x_{BJ}$) region and exploring the final-state parton propagation and hadronization processes under different nuclear medium conditions. Latest simulation studies of heavy flavor hadron and jet measurements with the EIC project detector conceptual design will be discussed. The projected statistical accuracy of heavy flavor jet and heavy flavor hadron inside jet measurements in comparison with latest theoretical calculations will be presented.

   nucl-exhep-exnucl-thEPJ Web Conf.(2024)·4 citations
2. 02*

   Production of Protons and Light Nuclei in Au+Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV with the STAR Detector

   STAR Collaboration: M. I. Abdulhamid · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · E. C. Aschenauer · S. Aslam · J. Atchison · V. Bairathi and 354 other authors

   We report the systematic measurement of protons and light nuclei production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 3 GeV by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum ($p_T$) spectra of protons ($p$), deuterons ($d$), tritons ($t$), ${}^3\mathrm{He}$, and ${}^4\mathrm{He}$ are measured from mid-rapidity to target rapidity for different collision centralities. We present the rapidity and centrality dependence of particle yields ($dN/dy$), average transverse momentum ($⟨p_T⟩$), yield ratios ($d/p$, $t/p$,${}^3\mathrm{He}/p$, ${}^4\mathrm{He}/p$), as well as the coalescence parameters ($B_2$, $B_3$). The 4$\pi$ yields for various particles are determined by utilizing the measured rapidity distributions, $dN/dy$. Furthermore, we present the energy, centrality, and rapidity dependence of the compound yield ratios ($N_p\times N_t/N_d^2$) and compare them with various model calculations. The physics implications of those results on the production mechanism of light nuclei and on QCD phase structure are discussed.

   nucl-exnucl-thPRC(2024)·46 citations
3. 03*

   Measurement of the jet mass and angularities in Pb-Pb collisions at 5.02 TeV with ALICE

   Ezra D. Lesser (on behalf of the ALICE collaboration)🇺🇸

   Jet substructure observables provide powerful tools to search for new physics and test theoretical descriptions of perturbative and non-perturbative processes in QCD. In heavy-ion collisions, jet substructure observables are used to elucidate the structure and dynamics of the quark-gluon plasma. Jet mass is one such observable, which probes the virtuality of hard-scattered partons and their modified fragmentation. Additionally, generalized jet angularities provide a powerful tool for differential measurements of the jet shower and its modification, as two parameters vary the weight of the jet constituents' relative angle and $p_{\mathrm{T}}$. Previous measurements of the jet mass and jet angularities have shown conflicting differences in comparison with models. To clarify these results, we present new measurements of the jet mass and jet angularities using an identical jet sample. The high-precision tracking system of ALICE enables these measurements over a broad range in $p_{\mathrm{T}}$, with low-$p_{\mathrm{T}}$ reach that is unique at the LHC. We report the generalized jet mass and jet angularities using charged-particle tracks in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Various jet angularity parameters are investigated for the jet resolution parameter $R=0.2$. Results are compared to pp collisions and theoretical models.

   nucl-exPoS(2024)·1 citation
4. 04*

   Higher-order moments of the elliptic flow distribution in PbPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   CMS Collaboration

   The hydrodynamic flow-like behavior of charged hadrons in high-energy lead-lead collisions is studied through multiparticle correlations. The elliptic anisotropy values based on different orders of multiparticle cumulants, $v_2\{2k\}$, are measured up to the tenth order ($k$ = 5) as functions of the collision centrality at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. The data were recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 0.607 nb${}^{-1}$. A hierarchy is observed between the coefficients, with $v_2\{2\}>v_2\{4\}\gtrsim v_2\{6\}\gtrsim v_2\{8\}\gtrsim v_2\{10\}$. Based on these results, centrality-dependent moments for the fluctuation-driven event-by-event $v_2$ distribution are determined, including the skewness, kurtosis and, for the first time, superskewness. Assuming a hydrodynamic expansion of the produced medium, these moments directly probe the initial-state geometry in high-energy nucleus-nucleus collisions.

   nucl-exhep-exJHEP(2024)·14 citations
5. 05*

   Low spin spectroscopy of neutron-rich 43,44,45Cl via {\beta} and (\beta}n decay

   V. Tripathi🇺🇸 · S. Bhattacharya🇮🇳 · E. Rubino🇺🇸 · C. Benetti · J. F. Perello · S. L. Tabor · S. N. Liddick🇺🇸 · P. C. Bender🇺🇸 · M. P. Carpenter🇺🇸 · J. J. Carroll🇺🇸 · A. Chester🇺🇸 · C. J. Chiara🇺🇸 and 18 other authors

   {\beta} decay of neutron-rich isotopes 43,45 S,studied at the National Superconducting Cyclotron Laboratory is reported here. {\beta} delayed {\gamma} transitions were detected by an array of 16 clover detectors surrounding the Beta Counting Station which consists of a 40x40 Double Sided Silicon Strip Detector followed by a Single Sided Silicon Strip Detector. {\beta} decay half-lives have been extracted for 43,45 S by correlating implants and decays in the pixelated implant detector with further coincidence with {\gamma} transitions in the daughter nucleus. The level structure of 43,45 Cl is expanded by the addition of 20 new {\gamma} transitions in 43Cl and 8 in 45 Cl with the observation of core excited negative-parity states for the first time. For 45 S decay, a large fraction of the {\beta} decay strength goes to delayed neutron emission populating states in 44 Cl which are also presented. Comparison of experimental observations is made to detailed shell-model calculations using the SDPFSDG-MU interaction to highlight the role of the diminished N = 28 neutron shell gap and the near degeneracy of the proton s 1/2 and d 3/2 orbitals on the structure of the neutron-rich Cl isotopes. The current work also provides further support to a ground state spin-parity assignment of 3/2 + in 45 Cl.

   nucl-exPRC(2024)·5 citations
6. 06*

   Measurement of (anti)alpha production in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   In this letter, measurements of (anti)alpha production in central (0$-$10%) Pb$-$Pb collisions at a center-of-mass energy per nucleon$-$nucleon pair of $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are presented, including the first measurement of an antialpha transverse-momentum spectrum. Owing to its large mass, the production of (anti)alpha is expected to be sensitive to different particle production models. The production yields and transverse-momentum spectra of nuclei are of particular interest because they provide a stringent test of these models. The averaged antialpha and alpha spectrum is compared to the spectra of lighter particles, by including it into a common blast-wave fit capturing the hydrodynamic-like flow of all particles. This fit is indicating that the (anti)alpha also participates in the collective expansion of the medium created in the collision. A blast-wave fit including only protons, (anti)alpha, and other light nuclei results in a similar flow velocity as the fit that includes all particles. A similar flow velocity, but a significantly larger kinetic freeze-out temperature is obtained when only protons and light nuclei are included in the fit. The coalescence parameter $B_4$ is well described by calculations from a statistical hadronization model but significantly underestimated by calculations assuming nucleus formation via coalescence of nucleons. Similarly, the (anti)alpha-to-proton ratio is well described by the statistical hadronization model. On the other hand, coalescence calculations including approaches with different implementations of the (anti)alpha substructure tend to underestimate the data.

   nucl-exhep-exPLB(2024)·11 citations
7. 07*

   Observation of abnormal suppression of ${\mathrm{f}}_0$(980) production in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The dependence of ${\mathrm{f}}_0$(980) production on the final-state charged-particle multiplicity in p$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported. The production of ${\mathrm{f}}_0$(980) is measured with the ALICE detector via the ${\mathrm{f}}_0(980)\to {\pi }^{+}{\pi }^{-}$ decay channel in a midrapidity region of $-0.5<y<0$. Particle yield ratios of ${\mathrm{f}}_0$(980) to $\pi$ and ${\mathrm{K}}^{\ast }$(892)${}^0$ are found to be decreasing with increasing charged-particle multiplicity. The magnitude of the suppression of the ${\mathrm{f}}_0$(980)/$\pi$ and ${\mathrm{f}}_0$(980)/${\mathrm{K}}^{\ast }$(892)${}^0$ yield ratios is found to be dependent on the transverse momentum $p_{\mathrm{T}}$, suggesting different mechanisms responsible for the measured effects. Furthermore, the nuclear modification factor $Q_{\mathrm{pPb}}$ of ${\mathrm{f}}_0$(980) is measured in various multiplicity ranges. The $Q_{\mathrm{pPb}}$ shows a strong suppression of the ${\mathrm{f}}_0$(980) production in the $p_{\mathrm{T}}$ region up to about 4 GeV/$c$. The results on the particle yield ratios and $Q_{\mathrm{pPb}}$ for ${\mathrm{f}}_0$(980) may help to understand the late hadronic phase in p$-$Pb collisions and the nature of the internal structure of ${\mathrm{f}}_0$(980) particle.

   nucl-exhep-exPLB(2024)·16 citations
8. 08*

   Photoproduction of K${}^{+}$K${}^{-}$ pairs in ultra-peripheral collisions

   ALICE Collaboration

   K${}^{+}$K${}^{-}$ pairs may be produced in photonuclear collisions, either from the decays of photoproduced $\varphi (1020)$ mesons, or directly as non-resonant K${}^{+}$K${}^{-}$ pairs. Measurements of K${}^{+}$K${}^{-}$ photoproduction probe the couplings between the $\varphi (1020)$ and charged kaons with photons and nuclear targets. The kaon$-$proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of K${}^{+}$K${}^{-}$ pairs on lead ions in ultra-peripheral collisions using the ALICE detector, including the first investigation of direct K${}^{+}$K${}^{-}$ production. There is significant K${}^{+}$K${}^{-}$ production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range $1.1<M_{\mathrm{KK}}<1.4$ GeV/$c^2$ above the $\varphi (1020)$ resonance, for rapidity $|y_{\mathrm{KK}}|<0.8$ and $p_{\mathrm{T},\mathrm{KK}}<0.1$ GeV/$c$, the measured coherent photoproduction cross section is $\mathrm{d}\sigma /\mathrm{d}y$ = 3.37 $\pm 0.61$ (stat.) $\pm 0.15$ (syst.) mb. The center-of-mass energy per nucleon of the photon-nucleus (Pb) system $W_{\gamma \mathrm{Pb},\mathrm{n}}$ ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for $\varphi (1020)$ photoproduction alone. The mass spectrum is fit to a cocktail consisting of $\varphi (1020)$ decays, direct K${}^{+}$K${}^{-}$ photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct K${}^{+}$K${}^{-}$ photoproduction are presented.

   nucl-exhep-exPRL(2024)·22 citations
9. 09*

   Rapidity scan approach for net-baryon cumulants with a statistical thermal model

   Jianing Li🇨🇳 · Lipei Du🇨🇦 · Shuzhe Shi🇨🇳

   Utilizing rapidity-dependent measurements to map the QCD phase diagram provides a complementary approach to traditional beam-energy-dependent measurements around midrapidity. The changing nature of thermodynamic properties of QCD matter along the beam axis in heavy-ion collisions at low collision energies both motivates and poses challenges for this method. In this study, we derive the analytical cumulant-generating function for subsystems within distinct rapidity windows, while accounting for global net-baryon charge conservation of the full system. Rapidity-dependent net-baryon cumulants are then calculated for a system exhibiting inhomogeneity along the beam axis, and their sensitivity to finite acceptances through changing rapidity bin widths is explored. We highlight the nontrivial behaviors exhibited by these cumulants, underscoring their importance in establishing a noncritical baseline for interpreting net-proton cumulants in the search for the QCD critical point. Finally, we discuss the implications of the rapidity scan for mapping the QCD phase diagram within the current context.

   ↳ nucl-thhep-phnucl-exPRC(2024)·7 citations
10. 10*

    Magnetic dipole transition in ${}^{48}$Ca

    B. Acharya🇺🇸 · B. S. Hu🇨🇦 · S. Bacca🇩🇪 · G. Hagen🇺🇸 · P. Navrátil🇨🇦 · T. Papenbrock🇺🇸

    The magnetic dipole transition strength $B(M1)$ of ${}^{48}$Ca is dominated by a single resonant state at an excitation energy of 10.23 MeV. Experiments disagree about $B(M1)$ and this impacts our understanding of spin flips in nuclei. We performed ab initio computations based on chiral effective field theory and found that $B(M1:0^{+}\to 1^{+})$ lies in the range from $7.0$ to $10.2{\mu }_N^2$. This is consistent with a $(\gamma ,n)$ experiment but larger than results from $(e,e^{\prime })$ and $(p,p^{\prime })$ scattering. Two-body currents yield no quenching of the $B(M1)$ strength and continuum effects reduce it by about 10%. For a validation of our approach, we computed magnetic moments in ${}^{47,49}$Ca and performed benchmark calculations in light nuclei.

    ↳ nucl-thnucl-exPRL(2024)·16 citations
11. 11*

    Rapidity and Energy Dependences of Temperatures and Volume Extracted from Identified Charged Hadron Spectra in Proton-Proton Collisions at a Super Proton Synchrotron (SPS)

    Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

    The standard (Bose-Einstein/Fermi-Dirac or Maxwell-Boltzmann) distribution from the relativistic ideal gas model is used to study the transverse momentum ($p_T$) spectra of identified charged hadrons (${\pi }^{-}$, ${\pi }^{+}$, $K^{-}$, $K^{+}$, $\bar{p}$, and $p$) with different rapidities produced in inelastic proton-proton ($pp$) collisions at the Super Proton Synchrotron (SPS). The experimental data measured by the NA61/SHINE Collaboration at the center-of-mass (c.m.) energies $\sqrt{s}=6.3$, 7.7, 8.8, 12.3, and 17.3 GeV are fitted well by the distribution. It is shown that the effective temperature ($T_{eff}$ or $T$), kinetic freeze-out temperature ($T_0$), and initial temperature ($T_i$) decrease with the increase in rapidity and increase with the increase in c.m. energy. The kinetic freeze-out volume ($V$) extracted from the ${\pi }^{-}$, ${\pi }^{+}$, $K^{-}$, $K^{+}$, and $\bar{p}$ spectra decreases with the rapidity and increase with the c.m. energy. The opposite tendency of $V$, extracted from the $p$ spectra, is observed to be increasing with the rapidity and decreasing with the c.m. energy due to the effect of leading protons.

    ↳ hep-phhep-exnucl-exnucl-thEntropy(2023)·7 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.