CAREER: Studies of Heavy Quarkonium Production in Relativistic Heavy-Ion Collisions at UC Davis.

University Of California-Davis, Davis CA

Investigators

Abstract

CAREER: Studies of Heavy Quarkonium Production in Relativistic Heavy-Ion Collisions at UC Davis. Abstract: In the study of the basic interactions of nature, one of the most intriguing is the strong nuclear interaction. This is the force which deals with quarks and gluons, which are the elementary particles that make up protons and neutrons, and are therefore the basic building blocks of all the matter we see around us. A key property of the strong interaction is that quarks and gluons are never seen in isolation, a phenomenon called "confinement". This behavior changes when nuclear matter is heated to extreme conditions. Calculations predict that normal nuclear matter exists up to a certain temperature. Above this temperature, there is a cross-over to a phase where nucleons dissolve such that their inner quarks and gluons are liberated. These "deconfined" quarks and gluons thus form a new state of nuclear matter, which has been called the Quark-Gluon Plasma (QGP). A few microseconds after the Big Bang, the universe is believed to have crossed this phase boundary, condensing from a QGP to a hadron gas as the temperature decreased. In the experimental front, producing the QGP in the laboratory and studying its properties is the main goal of experiments with heavy-ion collisions at high-energies. Two key issues in this search are a) producing evidence that the matter produced in the collisions consists of deconfined quarks and gluons, and b) determining that the temperature of the produced system is above the cross-over temperature. There are several avenues to attack the above issues, and in this proposal, one of them is addressed. This is the study of particles made of relatively heavy quark-antiquark pairs, which are bound by the strong force. These states are interesting because in a QGP, the high temperatures and the presence of deconfined lighter quarks and gluons modify the spectral properties of these heavy quark-antiquark states such that they no longer bind. When a heavy-ion collision forms a QGP, the production of these states is therefore suppressed relative to proton+proton or deuteron+nucleus collisions where no QGP is formed, providing a signature for deconfinement. Since the ground states and the excited states of these quark-antiquark particles melt at different temperatures, measuring the relative ratios provides experimentalists with a thermometer for this extremely hot matter. In this proposal, the Principal Investigator will measure the production of the heaviest available quark-antiquark bound states in heavy ion collisions. The investigations will be carried out at the highest energy accelerators for heavy ion collisions: with the STAR detector at the Relativistic Heavy-Ion Collider located in Brookhaven National Laboratory (Long Island, NY) and with the CMS detector at the Large Hadron Collider in the European Laboratory for High Energy Physics (CERN, Geneva, Switzerland). The PI will maintain an outreach program focusing on three components. He will mentor undergraduate students participating in the REU program at Davis. He is a member of the Society of the Advancement of Chicanos and Native Americans in Science (SACNAS). Through SACNAS, the PI communicates the excitement of heavy-ion research to future Latino scientists, mentors students during their annual conference, participates in the selection of student posters, and judges student presentations. Finally, he will develop physics presentations and demonstrations for the science students of the Cesar Chavez School, a Spanish-immersion school in Davis.