Dijet Angular Distributions in $$p\bar{p}$$ Collisions at $$\sqrt{s} = 1.8$$ TeV

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1996

DOI:https://doi.org/10.2172/1372333· OSTI ID:1372333

Fatyga, Mary Kathryn ^[1]

---

1. Univ. of Rochester, NY (United States)

We present measurements of diet angular distributions for events with two or more jets produced in $$p\bar{p}$$ collisions at the Fermilab Tevatron Collider at $$\sqrt{s}$$ = 1.8 TeV. The distribution of the scattering angle of a parton in the center-of mass reflects the dynamics of the interaction of two partons. This distribution was measured for different fixed regions of the diet invariant mass, in particular: 260 < $$M_{jj}$$ < 425, 475 < $$M_{jj}$$ < 635, $$M_{jj}$$ > 550, and $$M_{jj}$$ > 635 GeV / $c^2$ • Because the dijet angular distribution is expected to be relatively insensitive to the parton distribution within a proton, we can measure the properties of parton parton interactions without being concerned with the inability to calculate quantitative aspects of the substructure of the proton. We find that the next-to-leading order predictions of Perturbative Quantum Chromodynamics (QCD) show good agreement with the observed dijet angular distributions for all four mass ranges. At dijet invariant masses of greater than $$ \sim 500$$ GeV / $c^2$, the dijet angular distribution becomes sensitive to any new contact interactions originating from possible quark compositeness. In order to search for evidence that quarks are not point-like objects, but are rather bound states of more fundamental particles, we compared the predicted angular distribution with that measured in data for the mass range of $$M_{jj}$$ > 550 GeV /$c^2$. There was no departure from the expectations of next-to-leading-order Perturbative QCD, and we have used that to place a limit on the interaction scale for quark compositeness as $$\Lambda$$ > 1.8 TeV.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 1372333
• Report Number(s): FERMILAB-THESIS--1996-08; UMI--97-19940-MC; RX--1591 (ROCHESTER); 428631
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS