Improved measurement of the anti-d/anti-u asymmetry in the nucleon sea.

The NuSea collaboration Towell, R.S. ; McGaughey, P.L. ; Awes, T.C. ; et al.
Phys.Rev.D 64 (2001) 052002, 2001.
Inspire Record 554316 DOI 10.17182/hepdata.22184

Measurements of the ratio of Drell-Yan yields from an 800 \rm{GeV/c} proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of anti-down ($\bar{d}$) to anti-up ($\bar{u}$) quark distributions in the proton sea is determined over a wide range in Bjorken-$x$. These results confirm previous measurements by E866 and extend them to lower $x$. From these data, $(\bar{d}-\bar{u})$ and $\int(\bar{d}-\bar{u})dx$ are evaluated for $0.015<x<0.35$. These results are compared with parameterizations of various parton distribution functions, models and experimental results from NA51, NMC, and HERMES.

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Measurement of the light antiquark flavor asymmetry in the nucleon sea.

The NuSea collaboration Hawker, E.A. ; Awes, T.C. ; Beddo, M.E. ; et al.
Phys.Rev.Lett. 80 (1998) 3715-3718, 1998.
Inspire Record 468098 DOI 10.17182/hepdata.42153

A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140,000 Drell-Yan muon pairs with dimuon mass M_{mu+ mu-} >= 4.5 GeV/c^2 were recorded. From these data, the ratio of anti-down (dbar) to anti-up (ubar) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A strong x dependence is observed in the ratio dbar/ubar, showing substantial enhancement of dbar with respect to ubar for x<0.2. This result is in fair agreement with recent parton distribution parameterizations of the sea. For x>0.2, the observed dbar/ubar ratio is much nearer unity than given by the parameterizations.

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Search for first-generation scalar and vector leptoquarks

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; et al.
Phys.Rev.D 64 (2001) 092004, 2001.
Inspire Record 557085 DOI 10.17182/hepdata.42922

We describe a search for the pair production of first-generation scalar and vector leptoquarks in the eejj and enujj channels by the D0 Collaboration. The data are from the 1992--1996 ppbar run at sqrt{s} = 1.8 TeV at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the eejj and enujj channels are combined with those from a previous D0 analysis of the nunujj channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of beta, the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 GeV/c^2 are set on the mass for beta=1, 1/2, and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings.

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t anti-t production cross-section in p anti-p collisions at s**(1/2) = 1.8-TeV

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; et al.
Phys.Rev.D 67 (2003) 012004, 2003.
Inspire Record 586609 DOI 10.17182/hepdata.54899

Results are presented on a measurement of the ttbar pair production cross section in ppbar collisions at sqrt{s} = 1.8 TeV from nine independent decay channels. The data were collected by the Dzero experiment during the 1992-1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events are observed with an expected background of 38.8 +- 3.3 events. For a top quark mass of 172.1 GeV/c^2, the measured cross section is 5.69 +- 1.21 (stat) +- 1.04 (sys) pb.

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DIFFRACTIVE PRODUCTION OF pi- pi- pi+ IN 200-GeV/c pi- N INTERACTIONS

Joyner, R.W. ; Chang, C.C. ; Davis, T.C. ; et al.
Phys.Rev.D 39 (1989) 1865, 1989.
Inspire Record 22768 DOI 10.17182/hepdata.23242

This paper analyzes π−N→π−π−π+N events from Fermilab experiment E-580, using 200-GeV/c particles on a segmented target of plastic scintillator. Starting with 48 657 triggers, data-quality cuts and a cut on missing mass squared of M2<16 GeV2 lead to a final sample of 7205 events. The xF distribution of the 3π system shows almost all events in a sharp peak at xF=1, suggesting the presence of beam diffraction into three pions. The overall t’ distribution is fit to the sum of three exponential terms corresponding to coherent diffraction from carbon nuclei, diffraction from individual nucleons, and background. Cross sections per nucleon and exponential slopes are reported for each of the three components as a function of 3π effective mass. The cross section for diffraction from the nucleons in the target is 0.34±0.04 mb/nucleon. The cross section for coherent diffraction from carbon is 1.08±0.12 mb/nucleus. The exponential slope for diffraction is observed to decrease with increasing 3π effective mass. The fraction of coherent carbon diffraction in the total cross section is observed to decrease with increasing 3π effective mass. In the π−π+ effective-mass spectrum the ρ0(770) and f0(1270) are observed and their cross sections per nucleon are calculated. In the π−π−π+ effective-mass spectrum the A1−/A2− and A3− enhancements are observed and a cross section for the A3− is calculated.

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Resonance Production in Diffractive $\pi^- N \to K^0_s K^0_s \pi^- N^{\prime}$ at 200-GeV/c

Chen, T.Y. ; Jenkins, E.W. ; Johnson, K.J. ; et al.
Phys.Rev.D 28 (1983) 2304, 1983.
Inspire Record 182627 DOI 10.17182/hepdata.23787

The reaction π−N→KS0KS0π−N′ at 200 GeV/c has been observed with a sensitivity of 450±150 events/μb. The KS0KS0π− system exhibits substantial K*−(890)K0 production. Also produced are f0(1270)π−, f′(1515)π−, and K*−(1430)K0 final states. These resonances occur predominantly at threshold. The diffractive KS0KS0π− cross section is 3.4±1.1 μb. An enhancement near the A3−(1680) is observed in the KS0KS0π− invariant-mass distribution.

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Diffractive Production of $K^0_s K^0_s \pi^+ \pi^- \pi^-$ in $\pi^-N$ Interactions at 200-GeV/c

Chang, C.C. ; Davis, T.C. ; Diamond, R.N. ; et al.
Phys.Rev.D 29 (1984) 1888-1894, 1984.
Inspire Record 194648 DOI 10.17182/hepdata.23730

The diffractive dissociation of a 200-GeV/c π− beam into KS0KS0π+π−π− has been observed. The diffractive KS0KS0π+π−π− cross section is 1.59±0.78 μb. The ratio of the diffractive KS0KS0π+π−π− cross section to the diffractive KS0KS0π− cross section is 0.40±0.13, which is in good agreement with a diffractive-fragmentation-model prediction of 0.36. There is evidence for simultaneous production of K*− and K*+ in the diffractive KS0KS0π+π−π− sample. The K*+−KS0π−+ mass distribution shows an enhancement near 1.95 GeV.

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Observation of Double phi Meson Production in 400-GeV/c Proton - Nucleon Interactions

Davenport, T.F. ; Albright, John R. ; Goldman, J.H. ; et al.
Phys.Rev.D 33 (1986) 2519, 1986.
Inspire Record 218616 DOI 10.17182/hepdata.23536

The production of φ-meson pairs has been observed in 400-GeV/c proton-nucleon interactions at the Fermilab multiparticle spectrometer in the inclusive reaction pN→φφ+X, where each φ decays to a K+K− pair. A fast (200 nsec) high-level processor was used to selectively trigger on events containing two pairs of oppositely charged kaons having low invariant masses. The experimental apparatus and trigger processor are described. The cross section for φφ production and an upper limit for ηc production are presented.

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Inclusive Strange Particle Production in Single Vee Events in 200-GeV/c pi- n Interactions

Mikocki, S. ; Ficenec, J.R. ; Torres, S. ; et al.
Phys.Rev.D 34 (1986) 42, 1986.
Inspire Record 218617 DOI 10.17182/hepdata.23427

For the reaction π−N→V0X, where V0 is a Ks0, Λ, and Λ¯ and X are charged particles, we measured the transverse- and longitudinal-momentum distributions, and inclusive cross sections for the V0 and for K*±(892), Σ±(1385), and Ξ±(1321). We compare our results with predictions of quark-counting rules, and conclude that valence quarks play an important role in strange-particle production.

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Topological and Leading Particle Cross-Sections for 147-GeV/c $\pi^- p$ Interactions.

Fong, D.G. ; Heller, M. ; Shapiro, A.M. ; et al.
Phys.Lett.B 53 (1974) 290-296, 1974.
Inspire Record 93415 DOI 10.17182/hepdata.27916

Results are reported based on a study of π − p interactions at 147 GeV/ c in the FERMILAB 30-inch Proportional Wire Hybrid Bubble Chamber System. We have measured the topological cross sections and separated two-prong elastic and inelastic channels. In addition, we have extracted leading particle cross sections using the increased momentum resolution of the downstream proportional wire chambers. We have compared our results with experiments and predictions of a simple fragmentation hyphothesis.

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