44 research outputs found
Measurement of direct photon production at Tevatron fixed target energies
Measurements of the production of high transverse momentum direct photons by
a 515 GeV/c piminus beam and 530 and 800 GeV/c proton beams in interactions
with beryllium and hydrogen targets are presented. The data span the kinematic
ranges of 3.5 < p_T < 12 GeV/c in transverse momentum and 1.5 units in
rapidity. The inclusive direct-photon cross sections are compared with
next-to-leading-order perturbative QCD calculations and expectations based on a
phenomenological parton-k_T model.Comment: RevTeX4, 23 pages, 32 figures, submitted to Phys. Rev.
Evidence for Parton kT Effects in High pT Particle Production
Inclusive pizero and direct-photon cross sections in the kinematic range 3.5
< pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c
proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current
Next-to-Leading-Order perturbative QCD calculations fail to adequately describe
the data for conventional choices of scales. Kinematic distributions from these
hard scattering events provide evidence that the interacting partons carry
significant initial-state parton transverse momentum (kT). Incorporating these
kT effects phenomenologically greatly improves the agreement between
calculations and the measured cross sections.Comment: 11 pages including 6 pages of figures with caption
Production of pizero and eta mesons at large transverse momenta in pi-p and pi-Be interactions at 515 GeV/c
We present results on the production of high transverse momentum pizero and
eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the
kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75
in rapidity. The inclusive pizero cross sections are compared with
next-to-leading order QCD calculations and to expectations based on a
phenomenological parton-k_T model.Comment: RevTeX4, 15 pages, 15 figures, to be submitted to Phys. Rev.
Production of pizero and eta mesons at large transverse momenta in pp and pBe interactions at 530 and 800 GeV/c
We present results on the production of high transverse momentum pizero and
eta mesons in pp and pBe interactions at 530 and 800 GeV/c. The data span the
kinematic ranges: 1 < p_T < 10 GeV/c in transverse momentum and 1.5 units in
rapidity. The inclusive pizero cross sections are compared with next-to-leading
order QCD calculations and to expectations based on a phenomenological
parton-k_T model.Comment: RevTeX, 63 pages, 25 figures, to be submitted to Phys. Rev.
Towards a Ubiquitous Semantics of Interaction: phenomenology, scenarios and traces
Abstract. This paper begins a process of building a semantic framework to link the many diverse interface notations that are used in more formal communities of HCI. The focus in this paper is on scenarios – single traces of user behaviour. These form a point of contact between approaches that embody very different models of interface abstractions or mechanisms. The paper looks first at discrete time models as these are more prevalent and finds that even here there are substantive issues to be addressed, especially concerning the different interpretation of timing that become apparent when you relate behaviour from different models/notations. Ubiquitous interaction, virtual reality and rich media all involve aspects of more continuous interaction and the relevant models are reviewed. Because of their closer match to the real world, they are found to differ less in terms of ontological features of behaviour