Azimuthal Asymmetry and Transverse Momentum of Hadrons in Deep Inelastic Muon Scattering at 490 GeV

Thesis/Dissertation · Mon Feb 01 04:00:00 EST 1993

DOI:https://doi.org/10.2172/1425587· OSTI ID:1425587

Baker, Mark David ^[1]

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1. MIT

The forward charged hadrons produced in deep inelC1.stic scattering of 490 GeV muons from deuterium were studied. The data were taken by the E665 collaboration during the 1987-1988 Fermi lab fixed target run. $3 x10^4$ events ($6x10^4$ hadrons) were collected over a large range of kinematic variables: 100 GeV < $$\nu$$ < 500 GeV, 2 $GeV^2$ < $Q^2$ < 100 $GeV^2$, 0.003 < $$x_{\beta}$$, < 0.2, and 0.2 < $$y_{\beta}$$, < 0.9. Using the virtual photon axis as the z-axis, the distributions of the produced hadrons in azimuthal angle and in t ransverse momentum are examined. The primordial kJ.. of the struck parton and O($$\alpha_{s}$$)QCD effects are expected to contribute to an azimuthal asymmetry and to an increase in the average transverse momentum. Some theoretical work in the literature concerning these effects is described and some original results are derived concerning the effects of primordial kl. on the azimuthal d istribution . A Monte Carlo program is described which includes these theoretical effects and models fragmentation, the detector response, and the event reconstruction. The data exhibit several surprising effects. First, the phi asymmetry in the data is independent of $Q^2$ , while theoretically it should be more pronounced at low $Q^2$ and vanish at high $Q^2$ . Second, the phi asymmetry is carried by the most energetic particle in each event, which we call the Rank 1 particle, and there is very little phi asymmetry of the other charged hadrons. Third, this phi asymmetry in the Rank 1 particle is independent of the hadron energy fraction $$z_{\mathcal{h}}$$. The Monte Carlo predicts a strong $$z_{\mathcal{h}}$$ dependence and little rank dependence. Finally, the seagull plot shows an unexpected increase in t ransverse momentum $$P_{\tau}$$ for high energy hadrons ($$z_{\mathcal{h}}$$ > 0.4) as a function of $Q^2$ . It is clear from these results that more theoretical work is needed in order to understand primordial $$k_{\bot}$$. and the azimuthal asymmetry in deep inelastic scattering.

• 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: 1425587
• Report Number(s): FERMILAB-THESIS-1993-57; 369863
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS