NSF-BSF: Born-Oppenheimer Renormalization Group: Bridging Low and Intermediate X Physics in the Saturation Domain. Entanglement and High Energy Hadronic Reactions

University Of Connecticut, Storrs CT

Investigators

Abstract

The Electron Ion Collider (EIC), the next major nuclear physics facility, will explore the fundamental physics of Quantum Chromodynamics (QCD), the fundamental theory of strong interactions. One of its main goals is the experimental verification of the qualitatively new regime of QCD: parton saturation, which is predicted to occur in hadronic collisions at very high energy and/or large nuclei. In the extreme saturation regime, a hadron is similar to a "droplet" of fluid rather than a collection of free partons. However, the EIC will not achieve asymtotically high energies, and therefore to identify experimental manifestations of saturation one needs to bridge the asymptotic regime with the lower energy "partonic" picture. To this end, the PI and his collaborators will develop an approach to the hadronic evolution towards the saturated state which encompasses the effects important at asymptotic energies as well as those that dominate the physics at intermediate energies within one single unified framework. The team will study the relation between the entanglement properties of a hadronic wave function at high energy and the final states of a collision, with a special emphasis on understanding their collective behavior. The tantalizing question is the similarities and differences in behavior of soft (classical) modes and semi hard (intrinsically quantum) modes. The central topic of this project is to further develop and analyze the Born-Oppenheimer approach to quantum evolution, with emphasis on the interplay between low-x physics and intermediate-x physics, a crucial development for reliable applications of the theory saturation at EIC energies. The PI and his team will continue the study of particle production and correlations in the saturation framework, including correlated particle production in Deeply Inelastic Scattering (DIS) from high to low momentum transfer and searches for manifestation of quantum statistics of the gluon. The team will study theoretical questions that are fundamental to understanding and improving the high energy evolution, such as the further development of the Born-Oppenheimer approach for resumming large transverse logarithms at next to-leading order, thus unifying the approach to low-x and intermediate-x physics in a single framework. Furthermore, the team aims to understand the importance of quantum entanglement in the highly evolved hadronic wave function and to explore whether the properties of entanglement are reflected in the properties of the final state in collisions via the eigenstate-thermalization mechanism. These issues are crucial for reliable applications of the high-energy evolution approach to hadronic collisions of dense systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.