Sidney Padmanaban ‘ 26

Figure 1 Quarks are building blocks of matter, and by studying them, we can understand larger concepts of physics.

Large aspects of life cannot be studied without understanding the small building blocks that contribute to every part of the universe. Entire fields of physics and chemistry are dedicated towards the study of particles. Recently, two professors at Stony Brook University, Roy Lacey and Jiangyong Jia, conducted research using the Relativistic Heavy Ion Collider (RHIC) STAR detector in efforts to formulate a better understanding of quark-gluon plasma (QGP), a soup of quarks (elementary particles that are fundamental building blocks of matter) and gluons (subatomic particles that mediate interactions between quarks) that make up protons and neutrons of atomic nuclei. A persistent question in the chemistry field regarding QGP has been whether its shape is determined by the nucleons’ positions or by their internal structure. The research detailed in the STAR Collaboration paper suggests that the QGP shape created in the collisions of small and large nuclei is possibly influenced by the internal structure of the quarks and gluons inside the protons and neutrons of the smaller nucleus, rather than the previous data-supported conclusion from the PHENIX detector which showed that the shape was determined by the positions of the nucleons instead.

The measurements come from analyzing emerging particles mostly at the center of the detector around the beampipe. This is referred to as the midrapidity region, and here, researchers are able to look at the angles between pairs of particles and detect whether there are more particles flowing in certain directions. In order to analyze flow patterns, the team used three different collision systems against gold nuclei: single protons, two-nucleon deuterons (one proton and one neutron), and three-nucleon helium-3 nuclei (two protons and one neutron). After analyzing the patterns, the STAR team found that the imprint of the triangular shape of the helium-3 nucleus was absent, indicating that the nucleon substructure fluctuations play a more important role in the QGP shape determination than do the changes in number and positions of nucleons.

By understanding the collisions between different types of particles, scientists can get closer to answering the questions about the origin of matter generated in these collisions, and can apply that knowledge to larger questions still held about the universe. Measurements of shapes of QGP do not always match up, and by calculating these shapes in different ways, the research conducted by the STAR team advances science and furthers our understanding of the world around us. 

Works Cited:

[1] M.I. Abdulhamid et al., Measurements of the Elliptic and Triangular Azimuthal Anisotropies in Central 3He + Au, d + Au and p + Au Collisions at √sNN = 200 GeV. Physical Review Letters 130, (2023). doi: https://doi.org/10.1103/PhysRevLett.130.242301 

[2] Image retrieved from: https://www.freeimageslive.co.uk/free_stock_image/toy-blocks-jpg