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We report measurements of $\mathrm{\Upsilon }\left(1S\right)$, $\mathrm{\Upsilon }\left(2S\right)$and $\mathrm{\Upsilon }\left(3S\right)$production in $p+p$collisions at $\sqrt{s}=500\mathrm{GeV}$by the STAR experiment in year 2011, corresponding to an integrated luminosity ${\mathcal{L}}_{\mathrm{int}}=13{\mathrm{pb}}^{-1}$. The results provide precise cross sections, transverse momentum ( $p_{\mathrm{T}}$) and rapidity ( $y$) spectra, as well as cross section ratios for $p_{\mathrm{T}}<10\mathrm{GeV}/\mathrm{c}$and $\left|y\right|<1$. The dependence of the $\mathrm{\Upsilon }$yield on charged particle multiplicity has also been measured, offering new insights into the mechanisms of quarkonium production. The data are compared to various theoretical models: the color evaporation model (CEM) accurately describes the $\mathrm{\Upsilon }\left(1S\right)$production, while the color glass $\mathrm{condensate}+\text{nonrelativistic}$quantum chromodynamics ( $\mathrm{CGC}+\mathrm{NRQCD}$) model overestimates the data, particularly at low $p_{\mathrm{T}}$. Conversely, the color singlet model (CSM) underestimates the rapidity dependence. These discrepancies highlight the need for further development in understanding the production dynamics of heavy quarkonia in high-energy hadronic collisions. The trend in the multiplicity dependence is consistent with CGC/saturation and string percolation models or $\mathrm{\Upsilon }$production happening in multiple parton interactions modeled by 8. 

The STAR Collaboration reports precise measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for dijet production with at least one jet at intermediate pseudorapidity $0.8<{\eta }_{\text{jet}}<1.8$in polarized proton-proton collisions at a center-of-mass energy of 200 GeV. This study explores partons scattered with a longitudinal momentum fraction ( $x$) from 0.01 to 0.5, which are predominantly characterized by interactions between high- $x$valence quarks and low- $x$gluons. The results are in good agreement with previous measurements at 200 GeV with improved precision and are found to be consistent with the predictions of global analyses that find the gluon polarization to be positive. In contrast, the negative gluon polarization solution from the JAM Collaboration is found to be strongly disfavored. 

The ALICE Collaboration reports measurements of the large relative transverse momentum ( $k_T$) component of jet substructure in $pp$and Pb-Pb collisions at center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. Enhancement in the yield of such large- $k_{\mathrm{T}}$emissions in head-on Pb-Pb collisions is predicted to arise from partonic scattering with quasiparticles of the quark-gluon plasma. The analysis utilizes charged-particle jets reconstructed by the anti- $k_{\mathrm{T}}$algorithm with resolution parameter $R=0.2$in the transverse-momentum interval $60<p_{\mathrm{T},\mathrm{ch},\mathrm{jet}}<80\mathrm{GeV}/c$. The soft drop and dynamical grooming algorithms are used to identify high transverse momentum splittings in the jet shower. Comparison of measurements in Pb-Pb and $pp$collisions shows medium-induced narrowing, corresponding to yield suppression of high- $k_T$splittings, in contrast to the expectation of yield enhancement due to quasiparticle scattering. The measurements are compared to theoretical model calculations incorporating jet modification due to jet-medium interactions (“jet quenching”), both with and without quasiparticle scattering effects. These measurements provide new insight into the underlying mechanisms and theoretical modeling of jet quenching. 

Abstract Event-by-event fluctuations of the event-wise mean transverse momentum,$$\langle p_{\textrm{T}}\rangle $$ $⟨p_{\text{T}}⟩$, of charged particles produced in proton–proton (pp) collisions at$$\sqrt{s}$$ $\sqrt{s}$= 5.02 TeV, Xe–Xe collisions at$$\sqrt{s_{\textrm{NN}}}$$ $\sqrt{s_{\text{NN}}}$= 5.44 TeV, and Pb–Pb collisions at$$\sqrt{s_{\textrm{NN}}}$$ $\sqrt{s_{\text{NN}}}$= 5.02 TeV are studied using the ALICE detector based on the integral correlator$$\langle \!\langle \Delta p_\textrm{T}\Delta p_\textrm{T}\rangle \!\rangle $$ $⟨⟨\Delta p_{\text{T}}\Delta p_{\text{T}}⟩⟩$. The correlator strength is found to decrease monotonically with increasing produced charged-particle multiplicity measured at midrapidity in all three systems. In Xe–Xe and Pb–Pb collisions, the multiplicity dependence of the correlator deviates significantly from a simple power-law scaling as well as from the predictions of the HIJING and AMPT models. The observed deviation from power-law scaling is expected from transverse radial flow in semicentral to central Xe–Xe and Pb–Pb collisions. In pp collisions, the correlation strength is also studied by classifying the events based on the transverse spherocity,$$S_0$$ $S_0$, of the particle production at midrapidity, used as a proxy for the presence of a pronounced back-to-back jet topology. Low-spherocity (jetty) events feature a larger correlation strength than those with high spherocity (isotropic). The strength and multiplicity dependence of jetty and isotropic events are well reproduced by calculations with the PYTHIA 8 and EPOS LHC models. 

Abstract This paper presents a study of the inclusive forward J/ψyield as a function of forward charged-particle multiplicity in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV using data collected by the ALICE experiment at the CERN LHC. The results are presented in terms of relativeJ/ψyields and relative charged-particle multiplicities with respect to these quantities obtained in inelastic collisions having at least one charged particle in the pseudorapidity range |η|<1. The J/ψmesons are reconstructed via their decay intoμ⁺μ⁻pairs in the forward rapidity region (2.5< y <4). The relative multiplicity is estimated in the forward pseudorapidity range which overlaps with the J/ψrapidity region. The results show a steeper-than-linear increase of the J/ψyields versus the multiplicity. They are compared with previous measurements and theoretical model calculations. 

A<sc>bstract</sc> We report on the measurement of inclusive, non-prompt, and prompt J/ψ-hadron correlations by the ALICE Collaboration at the CERN Large Hadron Collider in pp collisions at a center-of-mass energy of 13 TeV. The correlations are studied at midrapidity (|y| <0.9) in the transverse momentum rangesp_T<40 GeV/cfor the J/ψand 0.15< p_T<10 GeV/cand |η|<0.9 for the associated hadrons. The measurement is based on minimum bias and high multiplicity data samples corresponding to integrated luminosities ofL_int= 34 nb⁻¹andL_int= 6.9 pb⁻¹, respectively. In addition, two more data samples are employed, requiring, on top of the minimum bias condition, a threshold on the tower energy ofE= 4 and 9 GeV in the ALICE electromagnetic calorimeters, which correspond to integrated luminosities ofL_int= 0.9 pb⁻¹andL_int= 8.4 pb⁻¹, respectively. The azimuthally integrated near and away side yields of associated charged hadrons per J/ψtrigger are presented as a function of the J/ψand associated hadron transverse momentum. The measurements are discussed in comparison to PYTHIA calculations. 

A<sc>bstract</sc> We report multi-differential measurements of strange hadron production ranging from mid- to target-rapidity in Au+Au collisions at a center-of-momentum energy per nucleon pair of$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{s_{\mathrm{NN}}}$= 3 GeV with the STAR experiment at RHIC.$$ {K}_S^0 $$ $K_S^0$meson and Λ hyperon yields are measured via their weak decay channels. Collision centrality and rapidity dependences of the transverse momentum spectra and particle ratios are presented. Particle mass and centrality dependence of the average transverse momenta of Λ and$$ {K}_S^0 $$ $K_S^0$are compared with other strange particles, providing evidence of the development of hadronic rescattering in such collisions. The 4πyields of each of these strange hadrons show a consistent centrality dependence. Discussions on radial flow, the strange hadron production mechanism, and properties of the medium created in such collisions are presented together with results from hadronic transport and thermal model calculations.