Studies of heavy ion collisions shed light on dense QCD systems and non-perturbative effects such as gluon saturation in nuclei, deconfinement and hadronization mechanism in medium. The LHCb collaboration has been developing a full heavy ion program studying dense QCD medium that utilizes both fixed-target and beam-beam collisions. Thanks to the forward instrumentation of the LHCb spectrometer, data taken with both collision configurations can probe unique kinematic regions at small and large Bjorken-x in detail. The precise vertexing and full particle identification allow a wide variety of hadron species to be reconstructed down to very low transverse momentum. The fixed-target configuration covers an unexplored energy range that lies between the SPS and the top RHIC energy.
We present new LHCb results from both beam-beam and fixed-target collisions, including nuclear modification at low Bjorken-x, heavy quark hadronization in small and large systems, charm production in fixed-target collisions and charmonium photoproduction in ultraperipheral PbPb collisions. We will also discuss recent LHCb upgrades and their impact on the heavy ion program.
Jiayin Sun is currently a senior postdoc at INFN Cagliari, Italy and a convener of the Ions and Fixed-Target working group at the LHCb experiment. She received her Ph.D. in experimental nuclear physics from Stony Brook University in 2016, where she worked on the measurement of di-electron invariant mass spectrum in Au+Au collisions at 200GeV with the Hadron Blind Detector at the PHENIX experiment. Then she joined the LHCb experiment as a postdoc in Tsinghua University, working on open heavy flavor productions in proton-lead collisions. Afterwards she continued her postdoctoral research at INFN Cagliari on topics including particle collective flow, heavy flavor productions at LHCb. Her main research interests include initial state effects, heavy flavor production in heavy ion physics.