Year-end Sale % OFF 
Abstract
We investigate dijet production from proton-nucleus collisions at the Large Hadron Collider (LHC) as a means for observing superfast quarks in nuclei with Bjorken $x>1$. Kinematically, superfast quarks can be identified through directly measurable jet kinematics. Dynamically, their description requires understanding several elusive properties of nuclear QCD, such as nuclear forces at very short distances, as well as medium modification of parton distributions in nuclei. In the present work, we develop a model for nuclear parton distributions at large $x$ in which the nuclear dynamics at short distance scales are described by two- and three-nucleon short range correlations (SRCs). Nuclear modifications are accounted for using the color screening model, and an improved description of the EMC effect is reached by using a structure function parametrization that includes higher-twist contributions. We apply QCD evolution at the leading order to obtain nuclear parton distributions in the kinematic regime of the LHC, and based on the obtained distributions calculate the cross section for dijet production. We find not only that superfast quarks can be observed at the LHC, but also that they provide sensitivity to the practically unexplored three-nucleon SRCs in nuclei. Additionally, the LHC can extend our knowledge of the EMC effect to large $Q^2$ where higher-twist effects are negligible.
Highlights
Another interesting aspect of nuclear quantum chromodynamics (QCD) is the possibility for quarks to carry a light cone momentum fraction higher than that of a free nucleon at rest
We develop a model for nuclear parton distributions at large x in which the nuclear dynamics at short distance scales are described by two- and three-nucleon short range correlations (SRCs)
We find that the rates of the dijet production in p A collisions at kinematics accessible by ATLAS and CMS are sufficient to observe superfast quarks and to get information about the practically unexplored three-nucleon SRCs in nuclei
Summary
Another interesting aspect of nuclear QCD is the possibility for quarks to carry a light cone momentum fraction higher than that of a free nucleon at rest. We propose a new approach for probing superfast quarks by considering dijet production in protonnucleus collisions at LHC kinematics This approach is based on the possibility of relating the light cone momentum fractions of the initial partons to the measured kinematics of dijets; by selecting transverse jet momenta and pseudo-rapidities, one can isolate scattering off the superfast quarks within the nucleus. We develop a theoretical framework for calculating this reaction, which requires addressing several issues, such as modeling the high-momentum (short range) properties of the nuclear wave function, and calculating the medium modification of parton distributions within the nucleus and evolving this modification to the large Q2 values relevant to the LHC. The Appendix gives detailed derivations of the factorization formula and the SRC parts of the nuclear light cone fraction distributions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
