We present results on the production of direct photons, pizero, and eta mesons on nuclear targets at large transverse momenta (p_T). The data are from 530 and 800 GeV/c proton beams and 515 GeV/c piminus beams incident upon copper and beryllium targets that span the kinematic range of 1.0 < p_T < 10 GeV/c at central rapidities.

We present results on the production of high transverse momentum pi(0) 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 -0.75less than or equal toy(cm)less than or equal to0.75 in rapidity. The inclusive pi(0) cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k(T) model.

Measurements of the production of high transverse momentum direct photons by a 515 GeV/c pi(-) 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.

We present measurements of the production of high transverse momentum pi(0) 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 pi(0) cross sections are compared with next-to-leading order QCD calculations and to expectations based on a phenomenological parton-k(T) model.

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.

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Inclusive pi(0) and direct-photon cross sections in the kinematic range 3.5 < p(T) < 12 GeV/c with central rapidities (y(cm)) are presented for 530 and 800 GeV/c proton beams and a 515 GeV/c pi(-) beam incident on Be 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 (k(T)) Incorporating these k(T) effects phenomenologically greatly improves the agreement between calculations and the measured cross sections. [S0031-9007(98)07206-8].

Inclusive {pi}{sup 0} and direct-photon cross sections in the kinematic range 3.5{lt}p{sub T}{lt}12 GeV/c with central rapidities (thinspy{sub cm} ) are presented for 530 and 800 GeV/c proton beams and a 515 GeV/c {pi}{sup {minus}} beam incident on Be 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 (k{sub T} ). Incorporating these k{sub T} effects phenomenologically greatly improves the agreement between calculations and the measured cross sections. {copyright} {ital 1998} {ital The American Physical Society}

G. Alverson,“) W. F. Baker,@lG. Ballocchi,@) R. Benson,‘“D. Berg,@) S. Blusk,@) C. Bromberg,‘“) D. Brown,(B) D. Carey,‘2) T. Chand,‘?) C. Chandlee,‘3) B. C. Choudhary,c7) W. H. Chung,@’ L. de Barbara,@) W. Desoi,‘3) W. Dlugosz,‘l) J. Dunlea,‘3) S. Ease,@) E. Engels, Jr.J5) W. Faissler,ol G. Fanourakis,@) T. Ferbel,@) D. Garelicka(‘) G. Ginther,@) G. Glass,o) M. Glaubman,“) P. Gutierrez,‘3) K. Hartman,@) J. Huston,‘@C. Johnstone,@) V. Kapoor,(7) I. Kourbanis,“) A. Lanaro,@) C. Lirakis,“) F. Lobkowicz,@) P. Lukens,@) S. Mani,‘mA. Maul,@) J. Mansour,@) R. Miller,@) C. A. Nelson, Jr., (*)B. Oh,@) D. Orris,‘s) E. Pothier,“)E. Prebys,@’ B. M. Rajaram,“) R. Roser,(3) K. RuddickJ4) P. Shepard,@) R. K. Shivpuri,“)A. Sinanidis,“’ D. Skow,Q) P. Slattery,@)L. Sorrell,‘@ W. Toothacker,‘8)N. Varelas,@‘D. Weerasundara,‘5’ J. Whitmore,@) G. Wu,“)T. Yasuda,(‘)C. Yosef’)and M. Zielinski(3)

We present results on the production of high transverse momentum charm mesons in collisions of 515 GeV/c negative pions with beryllium and copper targets. The experiment recorded a large sample of events containing high transverse momentum (p(T)) showers detected in an electromagnetic calorimeter. From these data, a sample of charm mesons has been reconstructed via their decay into the fully charged K pi pi mode. A measurement of the single inclusive transverse momentum distribution of charged D mesons from 1 to 8 GeV/c is presented. An extrapolation of the measured differential cross section yields an integrated D+/- cross section of 11.4 +/- 2.7 (stat) +/- 3.3 (syst) mu b per nucleon for D+/- mesons with x(F) > 0. The data are compared with expectations based upon next-to-leading-order perturbative QCD, as well as with results from PYTHIA. We also compare our integrated D+/- cross section with measurements from other experiments.

We present the results of a study of hadronic jets produced in association with direct photons and π0's at large transverse momenta in π−Be and pBe collisions at 500 GeV/c. Using primarily charged particles to characterize the properties of the recoiling jets, we compare their fragmentation and angular distributions, and their correlation with the trigger particle, for both the γ and π0 event samples. We also compare the data with QCD calculations that incorporate current parton distribution functions.Received 9 September 1993DOI:https://doi.org/10.1103/PhysRevD.49.3106©1994 American Physical Society

We present results from the initial run of Fermilab experiment E706. The data include incident pi- and p beams at 500 GeV/c on Be and Cu targets, and span the kinematic ranges of transverse momentum and rapidity of 3.5 less-than-or-equal-to p(T) less-than-or-equal-to 10 GeV/c and -0.7 less-than-or-equal-to y(c.m.) less-than-or-equal-to 0.7, respectively. We have measured cross sections for pi0 and direct-photon production, as well as the eta/pi0 production ratio. Rom the data on Be and Cu, we have extracted the nuclear dependence of pi0 production, parametrized as A(alpha). The cross sections are compared with next-to-leading-log QCD predictions for different choices of the QCD momentum scales and several sets of paxton distribution functions.

The L3 central tracking detector has been in operation since the start-up of LEP (Large Electron Positron collider) in 1989. This detector consists of a Time Expansion Chamber (TEC), a layer of Plastic Scintillating Fibers and a Z-chamber. The TEC gives a high spatial resolution and an excellent multi-track reconstruction capability. The fibers are designed to calibrate the drift velocity with high precision. The Z-Chamber provides TEC with accurate information about the z-coordinates of the tracks. A description of the design and the infrastructure of these three detectors, including the readout and data acquisition system, is given. The performance of the detectors during the 1990 and 1991 LEP running periods is presented.

We present new measurements of ${\ensuremath{\pi}}^{0}$ production at high transverse momenta (${p}_{T}$) for ${\ensuremath{\pi}}^{\ensuremath{-}}$ and $p$ interactions on Be and Cu targets at 500 GeV/c. The observed dependence of the yields as a function of ${p}_{T}$ and rapidity ($y$) is compared with expectations from leading-log QCD over a kinematic range in which the inclusive cross sections fall by more than 4 order of magnitude.

We present new measurements of pi-0 production at high transverse momenta (p(T)) for pi- and p interactions on Be and Cu targets at 500 GeV/c. The observed dependence of the yields as a function of p(T) and rapidity (y) is compared with expectations from leading-log QCD over a kinematic range in which the inclusive cross sections fall by more than 4 order of magnitude.

We report new measurements of inclusive direct photon production at high transverse momenta (p(T)) for pi- and p-interactions on Be at 500 Gev/c. The yields as a function Of p(T) and rapidity (y) are in good agreement with expectations from next-to-leading-log QCD calculations employing recently extracted quark and gluon structure functions.