Bedfer, Y.
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Low Mass Dimuon Production at the {CERN} Proton - Anti-Proton Collider

The UA1 collaboration Albajar, C. ; Albrow, M.G. ; Allkofer, O.C. ; et al.
Phys.Lett.B 209 (1988) 397-406, 1988.
Inspire Record 261359 DOI 10.17182/hepdata.29936

We present a study of low mass dimuon events [ m ( μμ ) < 6 GeV/ c 2 ] from the UA1 experiment at the CERN p p collider. Contributions from semileptonic decays of heavy flavour particles, Drell-Yan type processes, J/ψ decays and leptonic decays of light mesons are extracted, and cross sections for high p T beauty and Drell-Yan production are derived. A limit for the branching fraction for the exotic decay B 0 →μ + μ − is also obtained. The cross section for section for low mass, high p T Drell-Yan prod uction is compared to the measured direct photon cross section using QED and QCD derived relationship. This relationship is used to infer a measurement of the single photon cross section at lower values of transverse momentum, where photons cannot be unambigously identified.

1 data table
Table 1

GLOBAL SYTEMATIC ERROR OF 30PCT HAS TO BE ADDED.


Some Properties of Charmed Particles Produced in Nucleus Interactions

Aoki, S. ; Arnold, R. ; Baroni, G. ; et al.
Phys.Lett.B 209 (1988) 113-118, 1988.
Inspire Record 261774 DOI 10.17182/hepdata.29940

The azimuthal correlation distribution of 102 charmed-particle pairs observed in the hybrid emulsion experiment WA75 is compared with theoretical predictions. The various pairs - (D − D 0 ), (D − D + ), (D 0 D 0 ) and (D + D 0 )-all s how, within statistical error, the same azimuthal correlation distribution, demonstrating its independence from the specific nature of the production channel. Among the decays of 150 charged charmed particles and 138 neutral ones seen, higher multiplicities are favoured for hadronic as opposed to semileptonic decays. The data are consistent with the muonic decays of charged D mesons proceeding through the channels (μ ± , v, K 0 ) and [μ ± , v, K ∗0 (892)] , the fraction through K 0 being 0.76±0.06.

5 data tables
Table 1

No description provided.

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Table 3

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Two Jet Mass Distributions at the {CERN} Proton - Anti-Proton Collider

The UA1 collaboration Albajar, C. ; Albrow, M.G. ; Allkofer, O.C. ; et al.
Phys.Lett.B 209 (1988) 127-134, 1988.
Inspire Record 261782 DOI 10.17182/hepdata.29947

Two-jet mass distributions have been measured as a function of centre-of-mass scattering angle for high-mass jet pairs produced in proton-antiproton collisions at the CERN collider operating at a centre-of-mass energy of 630 GeV. The agreement between QCD expectations and the experimental measurements has been used to place limits on the production cross section of an object X decaying into two jets. In particular we consider the existence of a massive colour octet of vector gauge bosons (axigluons). We exclude axigluons with a width Λ A < 0.4 m A and a mass m A in the range 150 < m A < 310 GeV/ c 2 (95% CL).

1 data table
Table 1

No description provided.


Direct Photon Production at the CERN Proton - anti-Proton Collider

The UA1 collaboration Albajar, C. ; Albrow, M.G. ; Allkofer, O.C. ; et al.
Phys.Lett.B 209 (1988) 385-396, 1988.
Inspire Record 261356 DOI 10.17182/hepdata.29949

Isolated photons, produced directly by a scattering process, have been observed in the UA1 experiment at the CERN p p collider at centre-of-mass energies √=546 GeV and √=630 GeV . Single and double photon differential cross sections have been determined and found to be consistent with the expectations of QCD.

6 data tables
Table 1

No description provided.

Table 2

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Evidence for Anomalous Prompt Photons in Deep Inelastic Muon Scattering at 200-{GeV}

The European Muon collaboration Aubert, J.J. ; Bassompierre, G. ; Becks, K.H. ; et al.
Phys.Lett.B 218 (1989) 248-256, 1989.
Inspire Record 261250 DOI 10.17182/hepdata.29855

The inclusive yield of photons has been measured from deep inelastic interactions of 200 GeV muons on hydrogen. After subtracting the contributions from hadron electromagnetic decays and Bethe-Heitler muon bremsstrahlung, residual photons are observed at low p T and low z at a mean level of 0.15±0.06 per interaction. The quark Compton scattering process is unable to explain the data, thus indicating an anomalous photon production.

2 data tables
Table 1

Z distribution of anomalous direct photons.

Table 2

PT distribution of anomalous direct photons.


Production of Low Transverse Energy Clusters in anti-p p Collisions at s**(1/2) = 0.2-TeV to 0.9-TeV and their Interpretation in Terms of QCD Jets

The UA1 collaboration Albajar, C. ; Albrow, M.G. ; Allkofer, O.C. ; et al.
Nucl.Phys.B 309 (1988) 405-425, 1988.
Inspire Record 261009 DOI 10.17182/hepdata.33326

The production of transverse energy clusters in minimum bias proton-antiproton collisions at the CERN SPS Collider is studied with the UA1 detector over a new range of centre of mass energies (√ s = 0.2−0.9 TeV). This study is intended to investigate how low in transverse momentum perturbative QCD is able to describe the dynamics of hadron collisions. We observe that clusters with transverse energy in excess of a few GeV exhibit properties in agreement with QCD expectations for parton scattering, supporting their interpretation in terms of jet production. We find that the jet-event rate represents a sizeable fraction of the inelastic rate and is increasing with √ s over the measured energy range.

8 data tables
Table 1

No description provided.

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Neutral Strange Particle Productions and Inelastic Cross-section in $\bar{p}$ Ta Reaction at 4-{GeV}/$c$

Miyano, K. ; Noguchi, Y. ; Yoshimura, Y. ; et al.
Phys.Rev.C 38 (1988) 2788-2798, 1988.
Inspire Record 261403 DOI 10.17182/hepdata.26211

The inclusive production of Ks0, Λ, Λ¯, and Ks0Λ in the p¯Ta reaction at 4 GeV/c was measured and compared with that in the p¯p reaction. The total inelastic and topological cross sections were also measured. The number of Λ’s produced in the p¯Ta reaction was 11.3 times larger than that expected from the geometrical cross section, which is defined as A2/3 times the cross section for the p¯p reaction. The yield ratio Λ¯/Λ was found to be 2×10−2. These values cannot be accounted for by a straightforward extension of the p¯N reaction. Besides, a correlation of 2 vees like Ks0-Λ could not prove their simultaneous production. Nuclear temperatures of 135 and 97 MeV were obtained from the kinetic energy spectra of Ks0 and Λ, respectively. The kinematical characteristics of the Ks0 and Λ produced were analyzed in terms of the fireball model.

34 data tables
Table 1

No description provided.

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rivet Analysis
A Search for $\omega \phi$ and $\phi \phi$ Production in the Reactions $\gamma \gamma \to K^+ K^- \pi^+ \pi^- \pi^0$ and $\gamma \gamma \to 2 K^+ 2 K^-$

The ARGUS collaboration Albrecht, H. ; Bockmann, P. ; Glaser, R. ; et al.
Phys.Lett.B 210 (1988) 273-277, 1988.
Inspire Record 260828 DOI 10.17182/hepdata.29918

The reaction γγ→K + K − π + π − π 0 has been observed for the first time, using the ARGUS detector at the e + e − storage ring DORIS II at DESY. The cross section shows an enhancement for W γγ close to 3 GeV/ c 2 . Searches for γγ→ωφ and for γγ→φφ leading to this final state, as well as for γγ→φφ→2K + 2K − , have been performed. The derived upper limits for ωφ and φφ production are compatible with q q q q model predictions.

2 data tables
Table 1

TOPOLOGICAL CROSS SECTION.

Table 2

95 PCT CL UPPER LIMITS.


Vector Resonances Around 1.6-{GeV} of the $\eta \pi^+ \pi^-$ System in the $\pi^- p$ Charge Exchange Reaction at 8.95-{GeV}/$c$

Fukui, S. ; Horikawa, N. ; Inaba, S. ; et al.
Phys.Lett.B 202 (1988) 441-446, 1988.
Inspire Record 261402 DOI 10.17182/hepdata.29989

High statistics data of the ηππ system in π − p → ηπ + π − n were obtained. A partial wave analysis was performed in the mass region between 1.37 and 1.85 GeV. Resonant structures were observed in the IJ PC = 11 −− wave around 1.6 GeV and in 13 −− around 1.7 GeV. The structure in 11 −− was fitted with a single Breit-Wigner and also fitted with two Breit-Wigner's. The result suggests the possible existence of two vector resonances around 1.6 GeV. The structure in 13 −− is considered to be the π 3 (1690).

3 data tables
Table 1

Result of single Breit Wigner fit around 1.6 GeV. Called here $M(1635).

Table 2

Results of double Breit Wigner fit around 1.6 GeV. $M(1446) and $M(1701).

Table 3

Result of Breit Wigner fit around 1.7 GeV.


Observation of the Charmed Baryon $\Lambda(c$) in $e^+ e^-$ Annihilation at 10-{GeV}

The ARGUS collaboration Albrecht, H. ; Bockmann, P. ; Glaser, R. ; et al.
Phys.Lett.B 207 (1988) 109-114, 1988.
Inspire Record 260826 DOI 10.17182/hepdata.29980

Using the ARGUS detector at DORIS II, we have studied the production of the charmed baryon Λ c in e + e − annihilation at centre-of-mass energies near 10 GeV. The Λ c + was seen in the three decay modes pK − π + , Λπ + π − π + and K̄ 0 p, with products of normalized cross section times branching ratio [ R ·Br] of (10.8±1.4±1.2)×10 −3 , 6.6±1.5±0.9)×10 −3 and (6.7±1.4±0.8)×10 −3 respectively. The measured mass for the Λ c was (2283.1±1.7±2.0) MeV/ c 2 . A limit on the decay rates to Λπ + is reported. The fragmentation function of the Λ c was measured.

2 data tables
Table 1

Data requested from authors.

Table 2

No description provided.