Probing the flavor dependence of proton's light-quark sea in the SeaQuest experiment at Fermilab

Surprisingly large flavor asymmetry of the light-quark sea in the proton was reported in deep-inelastic scattering and Drell-Yan experiments. The Bjorken-$x$ dependence of the $\bar{d}/\bar{u}$ ratio extracted from the Fermilab E866 experiment also revealed an intriguing drop at the highest values of $x$. The Fermilab E906/SeaQuest experiment was designed to measure $\bar{d}/\bar{u}$ with improved accuracy at high Bjorken-$x$. By detecting high-mass dimuon events produced in the interaction of 120 GeV proton beam with liquid hydrogen (LH₂) and deuterium (LD₂) targets, the SeaQuest experiment probes the $\bar{d}/\bar{u}$ ratio up to $x\approx 0.45$. Data collection has been completed and the status of data analysis for SeaQuest is presented. Two different methods for extracting the LD₂/LH₂ Drell-Yan cross section ratios for $0.1\leq x \leq 0.45$ are presented and the results are in reasonable agreement. These ratios allow for the extraction of $\bar{d}/\bar{u}$ revealing an absence of the drop at large $x$ reported earlier by E866. Results from this work are compared with various theoretical models for the flavor structure of the nucleon sea.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2021

Author dc:creator

• Dove, Jason

Contributors dc:contributor

• Peng, Jen-Chieh
• Makins, Naomi
• Shelton, Jessie
• Abbamonte, Peter

• nuclear
• physics
• proton
• fixed target
• parton distribution function
• Fermilab
• deep-inelastic scattering
• E906
• SeaQuest

Statement dc:rights

• Copyright 2020 Jason Dove

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/109313

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/109313