Mon·Sep 12, 2022Monday·September 12, 2022

1. 01*

   Observing the Ping-pong Modality of Isospin Degree of Freedom in Cluster Emission from Heavy Ion Reactions

   Yijie Wang🇨🇳 · Fenhai Guan🇨🇳 · Xinyue Diao🇨🇳 · Mengting Wan · Yuhao Qin🇨🇳 · Zhi Qin🇨🇳 · Qianghua Wu · Dong Guo · Dawei Si🇨🇳 · Sheng Xiao · Boyuan Zhang🇨🇳 · Yaopeng Zhang🇨🇳 and 27 other authors

   Two-body correlations of the isotope-resolved light and heavy clusters are measured in ${}^{86}$Kr+${}^{208}$Pb reactions at 25 MeV/u. The yield and kinetic variables of the $A=3$ isobars, triton and ${}^3$He, are analyzed in coincidence with the heavy clusters of $7\le A\le 14$ emitted at the earlier chance. While the velocity spectra of both triton and ${}^3$He exhibit scaling behavior over the type of the heavy clusters, the yield ratios of $\mathrm{t}{/}^3\mathrm{He}$ correlate reversely to the neutron-to-proton ratio $N/Z$ of the latter, showing the ping-pong modality of the $N/Z$ of emitted clusters. The commonality that the $N/Z$ of the residues keeps the initial system value is extended to the cluster emission in heavy ion reactions. The comparison of transport model calculations to the data is discussed.

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

   Recent progress on global and local polarization of hyperons in heavy-ion collisions

   Takafumi Niida🇯🇵

   Since the observation of $\Lambda$ global polarization at RHIC, indicating the most vortical fluid ever observed so far, many experimental and theoretical progresses have been made in understanding of vorticity and polarization phenomena in heavy-ion collisions. But there still exist open questions which are currently being studied. In these proceedings, recent experimental results on global and local polarization of hyperons in heavy-ion collisions are reviewed.

   nucl-exEPJ Web Conf.(2022)·1 citation
3. 03*

   Multiplicity dependence of ${\rm Y}$ production at forward rapidity in pp collisions at $\sqrt{s}$ = 13 TeV

   ALICE Collaboration

   The measurement of ${\rm Y}$(1S), ${\rm Y}$(2S), and ${\rm Y}$(3S) yields as a function of the charged-particle multiplicity density, $\text{d}{N}_{\text{ch}}/\text{d}\eta$, using the ALICE experiment at the LHC, is reported in pp collisions at $\sqrt{s}=$ 13 TeV. The ${\rm Y}$ meson yields are measured at forward rapidity ($2.5<y<4$) in the dimuon decay channel, whereas the charged-particle multiplicity is defined at central rapidity ($|\eta |<1$). Both quantities are divided by their average value in minimum bias events to compute the self-normalized quantities. The increase of the self-normalized ${\rm Y}$(1S), ${\rm Y}$(2S), and ${\rm Y}$(3S) yields is found to be compatible with a linear scaling with the self-normalized $\text{d}{N}_{\text{ch}}/\text{d}\eta$, within the uncertainties. The self-normalized yield ratios of excited-to-ground ${\rm Y}$ states are compatible with unity within uncertainties. Similarly, the measured double ratio of the self-normalized ${\rm Y}$(1S) to the self-normalized J/$\psi$ yields, both measured at forward rapidity, is compatible with unity for self-normalized charged-particle multiplicities beyond one. The measurements are compared with theoretical predictions incorporating initial or final state effects.

   nucl-exNPB(2025)·14 citations
4. 04*

   Neutron emission in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   In ultraperipheral collisions (UPCs) of relativistic nuclei without overlap of nuclear densities, the two nuclei are excited by the Lorentz-contracted Coulomb fields of their collision partners. In these UPCs, the typical nuclear excitation energy is below a few tens of MeV, and a small number of nucleons are emitted in electromagnetic dissociation (EMD) of primary nuclei, in contrast to complete nuclear fragmentation in hadronic interactions. The cross sections of emission of given numbers of neutrons in UPCs of ${}^{208}$Pb nuclei at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV were measured with the neutron zero degree calorimeters (ZDCs) of the ALICE detector at the LHC, exploiting a similar technique to that used in previous studies performed at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. In addition, the cross sections for the exclusive emission of one, two, three, four, and five forward neutrons in the EMD, not accompanied by the emission of forward protons, and thus mostly corresponding to the production of ${}^{207,206,205,204,203}$Pb, respectively, were measured for the first time. The predictions from the available models describe the measured cross sections well. These cross sections can be used for evaluating the impact of secondary nuclei on the LHC components, in particular, on superconducting magnets, and also provide useful input for the design of the Future Circular Collider (FCC-hh).

   nucl-exhep-exPRC(2023)·27 citations
5. 05*

   Fixed-target charmonium production and pion parton distributions

   Wen-Chen Chang🇹🇼 · Jen-Chieh Peng🇺🇸 · Stephane Platchkov🇫🇷 · Takahiro Sawada🇺🇸

   We investigate how charmonium hadroproduction at fixed-target energies can be used to constrain the gluon distribution in pions. Using nonrelativistic QCD (NRQCD) formulation, the $J/\psi$ and $\psi (2S)$ cross sections as a function of longitudinal momentum fraction $x_F$ from pions and protons colliding with light targets, as well as the $\psi (2S)$ to $J/\psi$ cross section ratios, are included in the analysis. The color-octet long-distance matrix elements are found to have a pronounced dependence on the pion parton distribution functions (PDFs). This study shows that the $x_F$ differential cross sections of pion-induced charmonium production impose strong constraints on the pion's quark and gluon PDFs. In particular, the pion PDFs with larger gluon densities provide a significantly better description of the data. It is also found that the production of the $\psi (2S)$ state is associated with a larger quark-antiquark contribution, compared with $J/\psi$.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·11 citations
6. 06*

   Interplay between core and corona from small to large systems

   Yuuka Kanakubo🇯🇵 · Yasuki Tachibana🇯🇵 · Tetsufumi Hirano🇯🇵

   We present new results in $p$+$p$ and Pb+Pb collisions at the LHC energies from the updated dynamical core--corona initialization framework (DCCI2). The fractions of final hadron yields originating from equilibrated and non-equilibrated components are extracted as functions of multiplicity. We find that the contributions from non-equilibrated components are non-negligible even in Pb+Pb collisions and affect $p_T$-integrated multi-particle correlations. These suggest the importance of non-equilibrated components for the sophisticated extraction of properties of the quark gluon plasma from comparisons between dynamical frameworks and experimental data.

   ↳ nucl-thnucl-exEPJ Web Conf.(2023)·3 citations
7. 07*

   Interactions between heavy quarks and tilted QGP fireballs in 200 AGeV Au+Au collisions

   Ze-Fang Jiang🇨🇳 · Shanshan Cao🇨🇳 · Wen-Jing Xing🇨🇳 · Xiaowen Li🇨🇳 · Ben-Wei Zhang🇨🇳

   Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions. Using an improved Langevin model coupled to a (3+1)-dimensional viscous hydrodynamic model, we study the nuclear modification factor ($R_{\text{AA}}$), directed flow ($v_1$) and elliptic flow ($v_2$) coefficients of heavy mesons and their decayed electrons at the RHIC energy. We find that the counter-clockwise tilt of the nuclear matter in the reaction plane results in a positive (negative) heavy flavor $v_1$ in the backward (forward) rapidity region, whose magnitude increases with the heavy quark transverse momentum. The difference in the heavy flavor $R_{\text{AA}}$ between different angular regions is also proposed as a complementary tool to characterize the asymmetry of the medium profile. Our model results are consistent with currently available data at RHIC and provide predictions that can be tested by future measurements.

   ↳ nucl-thnucl-exCPC(2023)·3 citations
8. 08*

   Performance of the ALICE Electromagnetic Calorimeter

   ALICE Collaboration

   The performance of the electromagnetic calorimeter of the ALICE experiment during operation in 2010-2018 at the Large Hadron Collider is presented. After a short introduction into the design, readout, and trigger capabilities of the detector, the procedures for data taking, reconstruction, and validation are explained. The methods used for the calibration and various derived corrections are presented in detail. Subsequently, the capabilities of the calorimeter to reconstruct and measure photons, light mesons, electrons and jets are discussed. The performance of the calorimeter is illustrated mainly with data obtained with test beams at the Proton Synchrotron and Super Proton Synchrotron or in proton-proton collisions at $\sqrt{s}=13$ TeV, and compared to simulations.

   ↳ physics.ins-dethep-exnucl-exJINST(2023)·45 citations
9. 09*

   The $\mathbf{X}(3872)$'s excitation and its connection with production at hadron colliders

   M.C. Gordillo🇪🇸 · F. De Soto🇪🇸 · J. Segovia🇪🇸

   The LHCb collaboration has found that the production rate of $X(3872)$ in proton-proton collisions decreases as final state particle multiplicity increases. Moreover, the ALICE experiment at CERN has observed that the number of deuterons produced increases with multiplicity, a behavior that is qualitatively different from that of the $X(3872)$. These experimental findings may point to a compact structure for the $X(3872)$ or, at least, that its hadronization could proceed through a charm-anticharm core. We have recently used a diffusion Monte Carlo method to solve the many-body Schrödinger equation that describes the $X(3872)$ as a $c\bar{c}q\bar{q}$ tetraquark system with quantum numbers $I^G(J^{PC})=0^{+}(1^{++})$ and $1^{-}(1^{++})$. According to our structural analysis, the quark--(anti-)quark correlations resemble light-meson--heavy-meson molecules of type $\omega J/\psi$ and $\rho J/\psi$, rather than the most extended $D{\bar{D}}^{\ast }$ interpretation. It was argued that this fact may be the key to make compatible the molecular features of the $X(3872)$ with its production observables. The same formalism allows us to compute the first color excited $c\bar{c}q\bar{q}$ tetraquark state with either $I^G(J^{PC})=0^{+}(1^{++})$ or $1^{-}(1^{++})$. A bound-state is found in each channel, their masses are around 4.0 GeV which is an energy region where many new exotic candidates have been collected by the Particle Data Group. Concerning their structural properties, these states cluster in a compact diquark-antidiquark arrangement which matches perfectly with a so-called Born-Oppenheimer tetraquark configuration. The promptly production rates of these states in proton-proton, proton-nucleus and nucleus-nucleus collisions should fall off equal to or even faster than those of the $X(3872)$.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2022)·10 citations
10. 10*

    Heavy-flavor meson and baryon production in high-energy nucleus-nucleus collisions

    Andrea Beraudo🇮🇹 · Arturo De Pace🇮🇹 · Daniel Pablos Alfonso🇮🇹 · Francesco Prino🇮🇹 · Marco Monteno🇮🇹 · Marzia Nardi🇮🇹

    We present a new model for the description of heavy-flavor hadronization in relativistic heavy-ion collisions. We explore its effect on the charmed hadron yields and kinematic distributions once the latter is applied at the end of transport calculations used to simulate the propagation of heavy quarks in the deconfined fireball produced in the collision. The model is based on the formation of color-singlet clusters through the recombination of charm quarks with light antiquarks or diquarks from the same fluid cell. This local mechanism of color neutralization leads to a strong space-momentum correlation, which provides a substantial enhancement of charmed baryon production and of the collective flow of all charmed hadrons.

    ↳ hep-phnucl-exnucl-thEPJ Web Conf.(2023)·0 citations
11. 11*

    Recent results with radiation-tolerant TowerJazz 180 nm MALTA Sensors

    Matt LeBlanc🇨🇭 · Phil Allport🇬🇧 · Igancio Asensi🇨🇭 · Dumitru-Vlad Berlea🇩🇪 · Daniela Bortoletto🇬🇧 · Craig Buttar🇬🇧 · Florian Dachs🇨🇭 · Valerio Dao🇨🇭 · Haluk Denizli🇹🇷 · Dominik Dobrijevic🇨🇭 · Leyre Flores🇨🇭 · Andrea Gabrielli🇨🇭 and 17 other authors

    To achieve the physics goals of future colliders, it is necessary to develop novel, radiation-hard silicon sensors for their tracking detectors. We target the replacement of hybrid pixel detectors with Depleted Monolithic Active Pixel Sensors (DMAPS) that are radiation-hard, monolithic CMOS sensors. We have designed, manufactured and tested the MALTA series of sensors, which are DMAPS in the 180 nm TowerJazz CMOS imaging technology. MALTA have a pixel pitch well below current hybrid pixel detectors, high time resolution (< 2 ns) and excellent charge collection efficiency across pixel geometries. These sensors have a total silicon thickness of between 50-300 $\mu$m, implying reduced material budgets and multiple scattering rates for future detectors which utilize such technology. Furthermore, their monolithic design bypasses the costly stage of bump-bonding in hybrid sensors and can substantially reduce detector costs. This contribution presents the latest results from characterization studies of the MALTA2 sensors, including results demonstrating the radiation tolerance of these sensors.

    ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2022)·1 citation

* 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.