Light Anti-Quark Flavor Asymmetry in the Nucleon Sea and the Nuclear Dependence of Anit-Quarks in Nuclei at the Seaquest Experiment

Abstract

is an experiment aimed at studying the anti-quark distributions of nucleons and nuclei. The experiment uses a 120 GeV/c proton beam extracted from the Main Injector at Fermilab to collide with various solid and cryogenic targets to study a variety of physics topics. The experiment takes advantage of the Drell-Yan process in order to probe specifically the high-x anti-quark distributions of the target nucleus. The acceptance of the spectrometer is tuned to explore the unprecedentedly high Bjorken-x region, thereby extending our knowledge of the anti-quark sea structure of nucleons and nuclei.A new Intensity-Extrapolation method was developed to counter the rate dependence challenge at SeaQuest. Using this method, the ratio of cross sections of liquid deuterium and liquid hydrogen, σ pd (x)/2σ pp (x), was measured in the range 0.1 ≤ x T ≤ 0.45. The results have been found to be consistently above 1 for all values of the measured range of x T . Also, a first look atd(x)/ū(x) is presented. The trend of the data points indicate that the ratio is consistently above 1 for the measured range of x T . These results (when combined with more data) will provide a key input in constraining many theoretical models that attempt to explain the origin of the nucleon sea.Using the same method, the nuclear dependence of the per-nucleon cross section ratio, R pA , of carbon, iron and tungsten versus deuterium studied as a function of x T , p T , andx F are reported. The results for x T are consistent with E772 indicating little nuclear de-I would like to thank Dr. Chuck Brown for his guidance and help. He was always ready for a stimulating physics discussion and never let go of a teachable moment. Working with him was competitive, fun and a great learning experience.My sincere thanks goes to Dr. Kei Nagai for the analysis help he provided. He made my life much easier by helping write, understand, and organize an efficient analysis code. vii I would like to thank Dr. Po-Ju Lin for all the "fun" times at Lab 6 working on repairing and installing the new St 1 drift chamber. Working with 20 micron sense wire was itself difficult but his company made it bearable and fun. I would like to thank Dr. Joshua Rubin for all the inspiring and intellectually stimulating physics discussions. I truly enjoyed our Daddios' diner venting sessions and napkin discussions. I would like to thank Dr. Michelle

Impact of LHCb 13 TeV W and Z pseudo-data on the parton distribution functions *

“…This conclusion also holds for using MMHT2014 [27] and PDF4LHC15 [49] PDFs in profiling analysis to study the impact of a new (pseudo-) data on updating the (blue band) for the fixed-target Drell-Yan cross section, , in the region of larger to be probed by the SeaQuest experiment [46] at Fermilab. For comparison, the higher-portion of the older E866 data [45] (black points) is also presented here.…”

“…. The E866 results stimulated an interest in performing a similar measurement out to larger with higher precision -the main objective of the subsequent SeaQuest/E906 experiment at Fermilab [46], from which…”

“…11. (color online) Theoretical predictions based on the updated CT14HERA2 (red band) and original CT14HERA2 (blue band) for the fixed-target Drell-Yan cross section,, in the region of larger to be probed by the SeaQuest experiment[46] at Fermilab. For comparison, the higher-portion of the older E866 data[45] (black points) is also presented here.…”

Nuclear modification of J/Psi and Drell-Yan production at the E906/SeaQuest experiment

“…As can be seen in 1.2, the α QED trends towards infinity with increasing Q 2 values, a direct consequence of the EM force becoming stronger due to the absence of screening from the surrounding vacuum as the EM probe approaches a charge. Conversely, the strong force coupling constant experiences a logarithmic decrease with increasing Q 2 , which is a direct consequence of The dependence of QED and QCD coupling constants to Q 2 [4] the charge screening that takes place when a "colored" probe approaches another colored charge, thereby minimizing the strength of the force. The fact that α QCD becomes small in the highenergy, short-distance regime is the distinctive feature of QCD referred to as asymptotic freedom,…”

“…This section will list each set of data cuts per level used in this analysis. Table 3.4: "Good spill" specifications from [4] These cuts are used to discard data from proton spills that have irregular scale readings or unreliable recorded process variables. For spills satisfying minimum requirements a useful data quality bit, "Spill.dataQuality = 0", is used to identify and gather qualifying spills.…”