A study of D⁰ production from 500 GeV π^---nucleon interactions

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1998

DOI:https://doi.org/10.2172/3129· OSTI ID:3129

Stenson, Kevin M. ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States); Fermilab

Fermilab experiment E791 took data during six months in 1991 using a 500 GeV π^- beam on platinum and diamond targets for the purpose of studying the production and decay of particles containing a charm quark. In this dissertation, results are presented on the production of the D⁰ and $$\bar{D}$$⁰ mesons using fully reconstructed D⁰→Kπ and D⁰→Kπππ decays. Specifically, the total forward production cross section is measured as well as differential cross sections as a function of the scaled longitudinal momentum, Feynman-x (x_F), and the transverse momentum squared (p_T²). The results are compared to theoretical predictions from a next-to-leading order (NLO) calculation and from a leading order Monte Carlo event generator, PYTHIA/JETSET, which uses parton showers to account for higher-order terms. The comparison is made to both the c quark predictions and the predictions for D mesons using the Peterson fragmentation scheme for the NLO calculation and the Lund string fragmentation for the PYTHIA/JETSET prediction. The data are also compared to previous measurements by other experiments which used a π^- beam. Assuming an A¹ dependence, the total forward cross section for the sum of D⁰ and $$\bar{D}$$⁰ production is measured to be Σ(D⁰/$$\bar{D}$$⁰; x_F>0)=15.4$$+1.8\atop{-2.3}$$ μbarns/nucleon, in good agreement with other experiments and the NLO prediction. The differential cross sections agree best with the NLO c quark prediction and the PYTHIA/JETSET D{sup 0} meson prediction. Several functions are fit to the differential cross sections. From the fits to the x_F distribution we find the x_F distribution peaks at x_F=0.013±0.004, significantly above zero as predicted by the harder pion parton distribution function. Fitting the shape of the x_F distribution to (1-x_F)_n, while not a good fit, gives n=4.61±0.19 for the rang e0.05<x_F<0.50. The p_T² shape is acceptably fit with the function e{sup b'p_T} with b'=2.41±0.03 over the range 1(GeV/c)²<p_T²<18(GeV/c)².

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Energy Research (ER)
• DOE Contract Number: AC02-76CH03000
• OSTI ID: 3129
• Report Number(s): FERMILAB-THESIS--1998-29; ON: DE00003129
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
C QUARKS
CROSS SECTIONS
D MESONS
DIFFERENTIAL CROSS SECTIONS
DISTRIBUTION FUNCTIONS
FORECASTING
FRAGMENTATION
LONGITUDINAL MOMENTUM
MESONS
PARTONS
PRODUCTION
TRANSVERSE MOMENTUM