Experimental Study of Low-ptHadron Fragmentation

Abstract

We present high-statistics results on the reactions a-^p-^c+X where a and c can be any of TT* , K^ ^ p ^ orp. The data were taken at 100 and 175 GeV/c incident momenta using the Fermilab Single-Arm Spectrometer operated over the kinematic range 0.2 <^ < 1.0 andpt^ 1.0 GeV/c. Investigating the x dependence of the data, we find agreement with a quark-parton picture, namely the cross sections have a power-law behavior in 1 -X independent of ^ beam and p t.We have performed a high-energy inclusive scattering experiment to study the process a + p -^c +X, where a and c can be any of TT* , /^*, p, or p. The production of particle c was measured over the Feynman x range 0.2 ^x^ 1.0, and the transverse momentum range 0.3 ^Pt^ 1.0 GeV/c. Data were taken using the Fermilab M6E beam line and the Single-Arm Spectrometer (SAS) facility with incident beam momenta of 100 and 175 GeV/c. This is the first high-energy, high-resolution study of beam fragmentation for incident particles other than protons with good Cherenkov identification.It has recently been suggested that the basic hadron constituents may reveal themselves in low'ptf soft hadronic processes as well as in leptoproduction and large-/>^ scatterings^ Several models have elaborated upon this idea, yielding

Measurement of the forward-backward asymmetry ofΛandΛ¯production inpp<

“…In this paper we examine the question of whether the Λ andΛ retain some memory of the proton and antiproton beam directions. We consider the picture in which a strange quark produced directly in the hard scattering of point-like partons, or indirectly in the subsequent showering, can coalesce with a diquark remnant of the beam to produce a lambda particle, with the probability increasing with decreasing rapidity difference between the proton and the lambda [1][2][3][4].…”

Ratio between two Λ andΛ¯production mechanisms in p scattering

“…The function f (y p − y) is observed to be independent, or depends only weakly, on the total center of mass energy √ s of the two colliding hadrons in the range 0.024 to 7 TeV, on the target Z = p,p, Be or Pb, on the transverse momentum p T of the Λ orΛ, or on sample composition [2]. We consider the picture in which an s quark produced in the scattering may coalesce with a ud diquark remnant of the beam proton and produce a Λ [2][3][4][5][6].…”