Speaker
DrZilong Chang(Brookhaven National Laboratory)
Description
Talk title: Spin Physics at the STAR experiment ---------- Speaker: Dr. Zilong Chang, Brookhaven National Lab ---------- Abstract: The proton structure has been studied extensively over the past a few decades, especially from the polarized Deep Inelastic Scattering (DIS) Experiments. However due to its limit coverage in $−^2$ phase space and inability to directly access gluon inside the proton, at Relativistic Heavy Ion Collider (RHIC), the world-only polarized proton collider, it provides excellent opportunities to study the internal structure of proton. At both √=200 and 510 GeV, the Solenoidal Tracker at RHIC (STAR) experiment has carried out a series of measurements from both longitudinally and transversely polarized collisions. The longitudinal double spin asymmetry, $_{}$ from inclusive jet and dijet production at √=200 GeV provided the first evidence of the positive gluon polarization for >0.05. At √=510 GeV, the same measurements have pushed the gluon polarization down to ∼0.02. The longitudinal single-spin asymmetry $_$ from $^±$ boson at √=510 GeV shows that -flavor sea quark polarization, $∆\overline{}$, is larger than the -flavor sea quark polarization, $∆\overline{}$. The transverse single-spin dependence of the azimuthal asymmetry of charged pions in a jet indicated the first evidence of transversity in the collisions. The results enable to test the universality and factorization-breaking effects in collisions for Transverse-Momentum Dependent (TMD) distributions. In this talk, I will present the published and current measurements from STAR that explore both the helicity distribution functions and transverse structure of the proton. ---------- Self-introduction: Zilong Chang got his B.S. in Physics from University of Science and Technology of China in 2010, and his Ph.D in Physics from Texas A&M University in 2016. Since 2017, he has been working at Brookhaven National Laboratory as a post-doc researcher. His doctoral dissertation is on measurements of longitudinal double-spin asymmetry for inclusive jet production from √ = 510 GeV polarized collisions at STAR. Currently he is working with the same dataset to extract the inclusive jet cross-section to explore the gluon parton distribution function inside the proton.
