This report investigates the infrared structure of QCD through the lens of the Cho–Faddeev–Niemi decomposition and Faddeev–Niemi effective theory. We argue that gluon knots, as topological solitons characterized by the Hopf invariant, constitute the relevant infrared ground-state degrees of freedom of Yang–Mills fields. Within this framework, we present a unified mechanism for monopole...
Quarkonia are excellent probes for studying the interactive properties of quark-gluon plasma formed in relativistic heavy-ion collisions. To correctly interpret the observed suppression of quarkonium production in $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{\text{NN}}}$ = 200 GeV, the cold nuclear matter (CNM) effects in $p+\text{Au}$ collisions are quantified by the nuclear modification...
We investigate the production of open-flavor hadrons in $ pp $ collisions at $ \sqrt{ s_{ NN } } $ = 5.02 TeV using the parton and hadron cascade model PACIAE. We introduce string tension enhancement mechanisms towards dipole and double-junction strings in the string fragmentation hadronization model. The transverse momentum spectra and the baryon-to-meson ratios of light and heavy...
The search for quark–gluon plasma (QGP)-like collectivity in small collision systems remains a central goal of high-energy nuclear physics. Recent results from O$+$O collisions suggest that strongly coupled, near-perfect-fluid behavior may emerge even in such small systems, motivating a detailed investigation of jet quenching in systems of reduced size. In this work, we study hadron and jet...
We investigate spin hydrodynamic properties with an focus on entropy production for massive spin 1/2 particles. We consider particle collisions both with and without the influence of chiral anomalies such as the chiral magnetic or vortical effects, encoded by Berry curvature. This manifests as a spatial shift ($\Delta$). In doing so we first define and entropy that makes use of the matrix...
Ultra-peripheral Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\mathrm{NN}}}=200~\mathrm{GeV}$ at RHIC provide a controlled setting for investigating nuclear-structure effects in the photonuclear production of forward neutrons. Although the two isobars have the same mass number, they differ in proton number and photonuclear response, making their neutron-tagged Coulomb-dissociation cross-section...
We report the first measurements of two-particle transverse-momentum correlations for midrapidity charged particles in fixed-target Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=3.0$--$7.7$ GeV using data collected by STAR during the Beam Energy Scan Phase II program [1]. Combined with previous BES-I measurements at $\sqrt{s_{\mathrm{NN}}}=7.7$--$200$ GeV [2], the relative dynamical correlator...
Directed flow $v_1$ has been used to probe the early dynamics in high-energy nuclear collisions. The vector meson $\phi(s\bar{s})$, with a mass comparable to that of light baryons and weak hadronic interactions, provides a unique probe of the interplay between particle production mechanisms and early-stage dynamics in high-density nuclear matter.
In this talk, we report measurements of...
In ultraperipheral collisions (UPCs) of relativistic heavy ions, the strong interaction is suppressed, providing a clean environment to study photon-nucleus and photon-photon interactions. Based on the 2025 Pb-Pb UPC data collected by the CMS experiment and developing a dedicated Monte Carlo event generator, this thesis focuses on the photoproduction mechanism of the vector meson excitation...
Measurements of identical pion femtoscopy offer insights into collision dynamics, such as collective expansion, geometry of the collision zone at freeze-out, final state interactions, etc. In addition to the quantum interference and Coulomb interactions among the pion pairs, Coulomb interactions between the pair and the net positive charge in the emitting source affect the final correlation...
