We have studied the diffractive dissociation into dijets of 500 GeV/c pions scattering coherently from carbon and platinum targets. Extrapolating to asymptotically high energies (where t(min)-->0), we find that when the per-nucleus cross section for this process is parametrized as sigma = sigma0Aalpha, alpha has values near 1.6, the exact result depending on jet transverse momentum. These values are in agreement with those predicted by theoretical calculations of color-transparency.
A model-independent partial-wave analysis of the S-wave component of the Kπ system from decays of D + mesons to the three-body K − π + π + final state is described. Data come from the Fermilab E791 experiment. Amplitude measurements are made independently for ranges of K − π + invariant mass, and results are obtained below 825 MeV/c 2 , where previous measurements exist only in two mass bins. This method of parametrizing a three-body decay amplitude represents a new approach to analysing such decays. Though no model is required for the S-wave, a parametrization of the relatively well-known reference P -and D-waves, optimized to describe the data used, is required. In this paper, a Breit-Wigner model is adopted to describe the resonances in these waves. The observed phase variation for the S-, P -and D-waves do not match existing measurements of I = 1 2 K − π + scattering in the invariant mass range in which scattering is predominantly elastic. If the data are mostly I = 1 2 , this observation indicates that the Watson theorem, which requires these phases to have the same dependence on invariant mass, may not apply to these decays without allowing for some interaction with the other pion. The production rate of K − π + from these decays, if assumed to be predominantly I = 1 2 , is also found to have a significant dependence on invariant mass in the region above 1.25 GeV/c 2 . These measurements can provide a relatively model-free basis for future attempts to determine which strange scalar amplitudes contribute to the decays.
We present the first direct measurements of the pion valence-quark momentum distribution which is related to the square of the pion light-cone wave function. The measurements were carried out using data on diffractive dissociation of 500 GeV/c pi(-) into dijets from a platinum target at Fermilab experiment E791. The results show that the /q&q> light-cone asymptotic wave function describes the data well for Q2 approximately 10 (GeV/c)(2) or more. We also measured the transverse momentum distribution of the diffractive dijets.
From a sample of 848+/-44 D(+)(s)-->pi(-)pi(+)pi(+) decays, we find gamma(D(+)(s)-->pi(-)pi(+)pi(+))/gamma(D(+)(s)-->straight phipi(+)) = 0.245+/-0.028(+0.019)(-0.012). Using a Dalitz plot analysis of this three body decay, we find significant contributions from the channels rho(0)(770)pi(+), rho(0)(1450)pi(+), f(0)(980)pi(+), f(2)(1270)pi(+), and f(0)(1370)pi(+). We also present the values obtained for masses and widths of the resonances f(0)(980) and f(0)(1370).
We have measured the differential production cross sections as a function of scaled momentum x p ϭ2 p/E c.m. of the identified hadron species ϩ , K ϩ , K 0 , K* 0 , , p, ⌳ 0 , and of the corresponding antihadron species in inclusive hadronic Z 0 decays, as well as separately for Z 0 decays into light (u, d, s), c and b flavors. Clear flavor dependences are observed, consistent with expectations based upon previously measured production and decay properties of heavy hadrons. These results were used to test the QCD predictions of Gribov and Lipatov, the predictions of QCD in the modified leading logarithm approximation with the ansatz of local parton-hadron duality, and the predictions of three fragmentation models. The ratios of production of different hadron species were also measured as a function of x p and were used to study the suppression of strange meson, strange and non-strange baryon, and vector meson production in the jet fragmentation process. The light-flavor results provide improved tests of the above predictions, as they remove the contribution of heavy hadron production and decay from that of the rest of the fragmentation process. In addition we have compared hadron and antihadron production as a function of x p in light quark ͑as opposed to antiquark͒ jets. Differences are observed at high x p , providing direct evidence that higher-momentum hadrons are more likely to contain a primary quark or antiquark. The differences for pseudoscalar and vector kaons provide new measurements of strangeness suppression for high-x p fragmentation products. ͓S0556-2821͑99͒06101-9͔
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.