Mon·Mar 25, 2024Monday·March 25, 2024

1. 01*

   Systematic study of flow vector fluctuations in $\sqrt{{\text{s}}_{{}_{\mathbf{NN}}}}=5.02$ TeV Pb-Pb collisions

   ALICE Collaboration

   Measurements of the $p_{\mathrm{T}}$-dependent flow vector fluctuations in Pb-Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=5.02\mathrm{TeV}$ using azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [1] is used to quantify the effects of flow angle and magnitude fluctuations separately. This paper extends previous studies to additional centrality intervals and provides measurements of the $p_{\mathrm{T}}$-dependent flow vector fluctuations at $\sqrt{s_{{}_{\mathrm{NN}}}}=5.02\mathrm{TeV}$ with two-particle correlations. Significant $p_{\mathrm{T}}$-dependent fluctuations of the ${\vec{V}}_2$ flow vector in Pb-Pb collisions are found across different centrality ranges, with the largest fluctuations of up to $\sim$15% being present in the 5% most central collisions. In parallel, no evidence of significant $p_{\mathrm{T}}$-dependent fluctuations of ${\vec{V}}_3$ or ${\vec{V}}_4$ is found. Additionally, evidence of flow angle and magnitude fluctuations is observed with more than $5\sigma$ significance in central collisions. These observations in Pb-Pb collisions indicate where the classical picture of hydrodynamic modeling with a common symmetry plane breaks down. This has implications for hard probes at high $p_{\mathrm{T}}$, which might be biased by $p_{\mathrm{T}}$-dependent flow angle fluctuations of at least 23% in central collisions. Given the presented results, existing theoretical models should be re-examined to improve our understanding of initial conditions, quark--gluon plasma properties, and the dynamic evolution of the created system.

   nucl-exPRC(2024)·7 citations
2. 02*

   Measurement of charged and full jet production and nuclear modification factor in pp and p--Pb collisions with ALICE

   Austin Schmier (for the ALICE collaboration)🇺🇸

   The study of jet production in small collision systems is essential for testing our understanding of perturbative and non perturbative QCD and cold nuclear matter (CNM) effects. In addition, studies at high multiplicity in small collision systems exhibit signatures of collectivity, which is still not fully understood within a unified picture across system size. Jet quenching in small systems is not observed within current measurement precision, calling for more precise jet measurements. Results of charged particle and fully reconstructed jet production in pp and p--Pb collisions are presented at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $8$ TeV, along with the corresponding nuclear modification factor $R_{\mathrm{pPb}}$ at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. These results are the most precise measurements of the $R_{\mathrm{pPb}}$ by ALICE to date. To investigate whether jet energy is redistributed in CNM, the cross-section ratios for different jet resolution parameters ($R$) are compared between pp and p--Pb collisions, as well as within each collision system. Finally, comparisons between data and model predictions are discussed. This result extends previous LHC measurements to lower jet transverse momentum, constraining hard parton production and fragmentation mechanisms applied in model calculations, and the impact of the nuclear-modified parton distribution function on jet production. This measurement also provides new constraints on jet quenching in small collision systems.

   nucl-exEPJ Web Conf.(2024)·0 citations
3. 03*

   Heavy multiquark systems as clusters of smaller units -- a diffusion Monte Carlo calculation --

   M.C. Gordillo🇪🇸 · J. Segovia🇪🇸

   Multiquark systems appear less frequently than mesons and baryons despite the enormous world-wide experimental effort that has been made during the last two decades. In this work, we will propose a possible explanation for that fact, restricting ourselves to the case of sets including only $c$ and $\bar{c}$ quarks. We will show that those multiquarks can be thought as different combinations of smaller units that associate together to produce colorless assemblies with a definite value of the total spin. For instance, for the $cccccc$ hexaquark with $S=0$, we have three possibilities: a set of six undistinguishable $c$ quarks, an association of two $ccc$ baryons, or a set of three $cc$ diquarks close together. This means we can have three different values for the mass of an open-charm hexaquark with $S=0$. Using the diffusion Monte Carlo method, we calculate all possible combinations compatible with tetraquark $cc\bar{c}\bar{c}$, pentaquark $cccc\bar{c}$, open-charm $cccccc$ and hidden-charm $ccc\bar{c}\bar{c}\bar{c}$ hexaquark structures with the minimum value of total spin ($S=0$ or $S=1/2$). We consider compact structures with radial wave functions including interactions between all the quarks in the cluster. We find that, in all cases, the mass of the multiquark decreases with the number of small units that conform the set of quarks. For instance, an open charm hexaquark made up of three diquarks has a smaller mass than a set of six of $c$ undistinguishable units. When the pieces that conform the multiquark are themselves colorless with a definite value of the total spin, the cluster splits into those smaller units that separate infinitely from each other.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·8 citations
4. 04*

   Bottomonium suppression from the three-loop QCD potential

   Nora Brambilla🇩🇪 · Tom Magorsch🇩🇪 · Michael Strickland🇺🇸 · Antonio Vairo🇩🇪 · Peter Vander Griend🇺🇸

   We compute the suppression of bottomonium in the quark-gluon plasma using the three-loop QCD static potential. The potential describes the spin-averaged bottomonium spectrum below threshold with a less than 1% error. Within potential nonrelativistic quantum chromodynamics and an open quantum systems framework, we compute the evolution of the bottomonium density matrix. The values of the quarkonium transport coefficients are obtained from lattice QCD measurements of the bottomonium in-medium width and thermal mass shift; we additionally include for the first time a vacuum contribution to the dispersive coefficient $\gamma$. Using the three-loop potential and the values of the heavy quarkonium transport coefficients, we find that the resulting bottomonium nuclear modification factor is consistent with experimental observations, while at the same time reproducing the lattice measurements of the in-medium width.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·21 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.