Collective flow from AA, pA to pp collisions - Toward a unified paradigm

I give an overview of the latest development in understanding collective phenomena in high-multiplicity hadronic final state from relativistic nucleus-nucleus, proton-nucleus and proton-proton collisions. Upon reviewing the experimental data and confronting them with theoretical models, a unified paradigm in describing the observed collectivity across all hadronic collision systems is emerging. Potential future paths toward addressing key open questions, especially on collectivity in small systems (pp, pA), are discussed.Comment: 9 pages, 6 figures, plenary contribution to Quark Matter 2017, February 5-11 (2017), Chicago (IL), US

Corruption and Resource Allocation: Evidence from China

Exploiting a unique data set containing transactions data from a panel of 769 Chinese state-owned enterprises between 1980 and 1989, this paper tests microeconomic implications of a pervasive form of corruption --official diversion of under-priced, in-plan goods to the market. Corruption has the predicted effects on resource allocation. Official under-pricing of in-plan goods, which lowers the marginal cost of diversion, increases the procurement of output into the plan for the purpose of diversion. Market competition introduced by allowing firms to sell directly to the market appears to reduce corruption and therefore lessen its distortions.http://deepblue.lib.umich.edu/bitstream/2027.42/39780/3/wp396.pd

System size dependence of two-particle angular correlations in p+p, Cu+Cu and Au+Au collisions

We present a systematic study of two-particle angular correlations in p+p, Cu+Cu and Au+Au collisions over a broad range of pseudorapidity and azimuthal angle. The PHOBOS detector has a uniquely large angular coverage for inclusive charged particles, which allows for the study of correlations on both long- and short-range scales. A complex two-dimensional correlation structure emerges which is interpreted in the context of a cluster model. The cluster size and its decay width are extracted from the two-particle pseudorapidity correlation function. The cluster size found in semi-central Cu+Cu and Au+Au collisions is comparable to that found in p+p but a non-trivial increase of cluster size with decreasing centrality is observed. Moreover, the comparison between Cu+Cu and Au+Au systems shows an interesting scaling of the cluster size with the measured fraction of total cross section (which is related to $b/2R$), suggesting a geometric origin. These results should provide insight into the hadronization stage of the hot and dense medium created in heavy ion collisions.Comment: 4 pages, 5 figures, presented at the 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur, India, February 4-10, 200

Observation of a "Ridge" correlation structure in high multiplicity proton-proton collisions: A brief review

This paper briefly reviews the striking experimental observation of a ridge-like dihadron correlation structure in high multiplicity proton-proton collisions at the Large Hadron Collider (LHC). Recent progress of both experimental and theoretical efforts on understanding the physical origin of the novel effect is reviewed. Outlook on future direction of possible new studies is discussed.Comment: 16 pages, 12 figures, brief review for Modern Physics Letter