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

Dove, Jason

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https://hdl.handle.net/2142/109313 Copy

Description

Title

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

Author(s)

Dove, Jason

Issue Date

2020-07-23

Director of Research (if dissertation) or Advisor (if thesis)

Peng, Jen-Chieh

Doctoral Committee Chair(s)

Makins, Naomi

Committee Member(s)

• Shelton, Jessie
• Abbamonte, Peter

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Date of Ingest

2021-03-05T21:33:11Z

Keyword(s)

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

Abstract

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 (LH$_2$) and deuterium (LD$_2$) 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 LD$_2$/LH$_2$ 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.

Graduation Semester

2020-12

Type of Resource

Thesis

Permalink

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

Copyright and License Information

Copyright 2020 Jason Dove

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