Thu·Dec 21, 2023Thursday·December 21, 2023

1. 01*

   Quarkonia as probes of initial and final states in small systems with ALICE

   Subikash Choudhury (for the ALICE Collaboration)🇮🇳

   The multiple parton$-$parton interactions (MPIs) are an important element to describe the observed collective flow and strangeness enhancement in high multiplicity pp and p$-$Pb collisions, the so-called small systems. At LHC energy, MPIs affect both soft and hard scales of the event. Since quarkonium production involves both, it can be an excellent tool to understand the role of MPIs in small systems. Study of multiplicity dependent quarkonium production provides an indirect probe of MPIs in hadronic collisions. Also, relative production of excited-to-ground quarkonium states as a function of multiplicity are sensitive to final state effects. Cross section measurements of different quarkonium states are also important to understand their production mechanisms. In these proceedings, first preliminary results of $\psi$(2S)-over-J/$\psi$ cross section measurements at mid and forward rapidity ($\text{y}$) from Run 2 and Run 3 pp collisions at $\sqrt{s}$ = 13 and 13.6 TeV, respectively will be presented. Preliminary results on ${\rm Y}$(nS) states (n = 1,2) cross sections and final multiplicity dependent measurements of excited-to-ground states quarkonium yields, at forward $\text{y}$, in pp collisions at $\sqrt{s}=$ 13 TeV will be shown. In addition, few performance plots from Run 3 in the quarkonium sector will be presented and discussed.

   nucl-exhep-exEPJ Web Conf.(2024)·1 citation
2. 02*

   The role of longitudinal decorrelations for measurements of anisotropic flow in small collision systems

   Sangwook Ryu🇺🇸 · Bjoern Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸

   Within a (3+1)D viscous hydrodynamic model we compute anisotropic flow in small system collisions as performed at the Relativistic Heavy Ion Collider and measured by the STAR and PHENIX Collaborations. We emphasize the importance of the rapidity dependence of the geometry for interpreting the differences encountered in measurements by the two collaborations.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2024)·5 citations
3. 03*

   Investigating the composition of the K${}_0^{\ast }(700)$ state with ${\pi }^{\pm }$K${}_{\mathrm{S}}^0$ correlations at the LHC

   ALICE Collaboration

   The first measurements of femtoscopic correlations with the particle pair combinations ${\pi }^{\pm }$K${}_{\mathrm{S}}^0$ in pp collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider (LHC) are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K${}_0^{\ast }(700)$ particle that has been considered a tetraquark candidate for over forty years. Source and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction in the ${\pi }^{\pm }$K${}_{\mathrm{S}}^0$ system is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter. The extracted mass and Breit-Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K${}_0^{\ast }(700)$. The small value and increase of the correlation strength with increasing source size support the hypothesis that the K${}_0^{\ast }(700)$ is a four-quark state, i.e. a tetraquark state of the form $({\mathrm{q}}_1,\overline{{\mathrm{q}}_2},{\mathrm{q}}_3,\overline{{\mathrm{q}}_3})$ in which ${\mathrm{q}}_1$, ${\mathrm{q}}_2$, and ${\mathrm{q}}_3$ indicate the flavor of the valence quarks of the $\pi$ and K${}_{\mathrm{S}}^0$. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K${}_0^{\ast }(700)$ resonance.

   ↳ hep-exnucl-exPLB(2024)·25 citations
4. 04*

   Performance of the Fully-equipped Spin Flip Chopper For Neutron Lifetime Experiment at J-PARC

   K. Mishima🇯🇵 · G. Ichikawa🇯🇵 · Y. Fuwa🇯🇵 · T. Hasegawa🇯🇵 · M. Hino🇯🇵 · R. Hosokawa🇯🇵 · T. Ino🇯🇵 · Y. Iwashita🇯🇵 · M. Kitaguchi🇯🇵 · S. Matsuzaki🇨🇳 · T. Mogi🇯🇵 · H. Okabe🇯🇵 and 10 other authors

   To solve the ''neutron lifetime puzzle,'' where measured neutron lifetimes differ depending on the measurement methods, an experiment with pulsed neutron beam at J-PARC is in progress. In this experiment, neutrons are bunched into 40-cm lengths using a spin flip chopper (SFC), where the statistical sensitivity was limited by the aperture size of the SFC. The SFC comprises three sets of magnetic supermirrors and two resonant spin flippers. In this paper, we discuss an upgrade to enlarge the apertures of the SFC. With this upgrade, the statistics per unit time of the neutron lifetime experiment increased by a factor of 2.8, while maintaining a signal-to-noise ratio of 250-400 comparable to the previous one. Consequently, the time required to reach a precision of 1 s in the neutron lifetime experiment was reduced from 590 to 170 days, which is a significant reduction in time. This improvement in statistic will also contribute to the reduction of systematic uncertainties, such as background evaluation, fostering further advancements in the neutron lifetime experiments at J-PARC.

   ↳ physics.ins-detnucl-exPTEP(2024)·1 citation
5. 05*

   Complete fusion of ${}^6$Li with ${}^{28}$Si and ${}^{64}$Ni nuclei in the framework of the continuum discretized coupled channel method

   S.R. Souza🇧🇷 · L.F. Canto🇧🇷 · R. Donangelo

   The complete fusion of ${}^6$Li with ${}^{28}$Si and ${}^{64}$Ni nuclei, ranging from subbarrier energies up to values well above the Coulomb barrier, is studied using the continuum discretized coupled channels method. We investigate the sensitivity of the results to the largest energy used in the discretization of the continuum, including closed channels. Our results reveal that, as long as the states in the continuum are not limited to too small energies, the specific upper bound adopted is not relevant as the complete fusion cross-section is fairly insensitive to it above a threshold. Convergence with respect to this parameter is rapidly reached, so that closed channels play a role only at low collision energies. A good agreement with the available experimental data is obtained.

   ↳ nucl-thnucl-ex0 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.