Beam Jet Structures in Soft and Hard Proton Proton Collisions $$\sqrt{s}$$ = 27.4-GeV

Thesis/Dissertation · Wed Oct 01 04:00:00 EDT 1986

DOI:https://doi.org/10.2172/1433230· OSTI ID:1433230

Ahn, Seung-Chan ^[1]

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1. Rutgers U., Piscataway

In this thesis we study the beam jet structures in soft and hard proton-proton collisions at $$\sqrt{s}$$ 27.4 GeV using charged particles. Data were taken using Fermilab Multiparticle Spectrometer triggered by a highly segmented calorimeter with $$\Delta\phi = 2 \pi$$ and $$45^\circ \leq \theta^* \leq 125°$$. The study of soft and hard collisions is done by scanning transverse energy$$(E_t)$$ in the calorimeter from 1 to 20 GeV whose corresponding $$x_T(= E_t/\sqrt{s}$$) ranges from 0.05 to 0.7. We find: for high $$E_t$$ (> 8 GeV) events, excessively soft beam fragmentation compared to the prediction of ISAJET model: $$E_t$$ scaling of beam fragmentation for negative particles and its violation for positive ones: at high $$E_t, E_t$$ scaling of beam fragmentation for both charges, and the approximately low planarity events at planarity P - 0.7 to designate jet and non-jet events. For high planarity events, we find the harder beam fragmentation and larger net charged energy flow. Positive particles are harder in high planarity events than in low planarity ones, and probably they are leading particles. constant ratio(= 1.73 ± 0.l5) of the beam fragmentation function of positive particle to that of negative ones at large x' (= $$2P^*_z/\sqrt{s}-E_t$$»: disappearance of the leading proton effect in the beam jet core. By comparison to $$\nu(\bar\nu)$$p data, we demonstrate a transition from diquark to single quark nature of the beam remnant, which amounts to the breakdown of 4-jet structure in high E t pp-collision; this breakdown is qualitatively consistent with multiple pairs of 2 ~ 2 subprocesses. Also studied are correlations of 90° jet and the beam jet using the "planarity" as a measure of 90° jet. We divide events into high and

• 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: 1433230
• Report Number(s): FERMILAB-THESIS-1986-11; UMI-87-04048; 240406
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS