Hemingway, R.J.
Electron production
DSIG/DU
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Measurement of Z / gamma* production in Compton scattering of quasi-real photons.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 24 (2002) 1-15, 2002.
Inspire Record 560307 DOI 10.17182/hepdata.49750

The process e+ e- -> e+ e- Z/gamma* is studied with the OPAL detector at LEP at a centre of mass energy of sqrt(s) = 189 GeV. The cross-section times the branching ratio of the Z/gamma* decaying into hadrons is measured within Lorentz invariant kinematic limits to be (1.2 +/- 0.3 +/- 0.1) pb for invariant masses of the hadronic system between 5 GeV and 60 GeV and (0.7 +/- 0.2 +/- 0.1) pb for hadronic masses above 60 GeV. The differential cross-sections of the Mandelstam variables s-hat, t-hat, and u-hat are measured and compared with the predictions from the Monte Carlo generators grc4f and PYTHIA. From this, based on a factorisation ansatz, the total and differential cross-sections for the subprocess e gamma -> e Z/gamma* are derived.

9 data tables
Table 1

Measured values of the cross section times the branching ratio for the (Z0/GAMMA*) decay into hadrons within the restricted kinematic limits.

Table 2

Differential cross-section dsig_ee/dm_qq.

Table 3

Differential cross-section dsigma_ee/dsqrt(shat).

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The Reactions $K^- p \to$ Pseudoscalar Meson $\Lambda(1520)$ at 4.2-{GeV}/$c$

The Amsterdam-CERN-Nijmegen-Oxford collaboration Barlag, S.J.M. ; Blokzijl, R. ; Jongejans, B. ; et al.
Nucl.Phys.B 149 (1979) 220-236, 1979.
Inspire Record 130106 DOI 10.17182/hepdata.34820

The total and differential cross sections of the reactions K − p → π 0 Λ (1520), ηΛ(1520) and η′ Λ(1520) have been measured. Prominent forward peaks are onserved in all three reactions. The first reaction shows also a backward peak. The spin density matrix elements of the Λ(1520) in this reaction are determined. For forward production the results show a remarkable alignment of the Λ(1520) corresponding to an M2 transition in the model of Stodolsky-Sakurai for 3 2 − baryon production.

12 data tables
Table 1

TOTAL (FORWARD AND BACKWARD) CROSS SECTIONS. THE ERRORS ARE MAINLY SYSTEMATIC.

Table 2

-TP = (-T - 0.04 GEV**2). MAX(-T) - MIN(-T) = 5.75 GEV**2.

Table 3

-UP = (-U - 0.20 GEV**2).

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The Reactions K- p --> Lambda pi0, Lambda eta, Lambda eta' at 4.2-GeV/c

The Amsterdam-CERN-Nijmegen-Oxford collaboration Marzano, F. ; Hemingway, R.J. ; Loverre, P.F. ; et al.
Nucl.Phys.B 123 (1977) 203-222, 1977.
Inspire Record 119257 DOI 10.17182/hepdata.35450

In a high statistics CERN 2 m bubble chamber experiment the differential cross sections and polarizations of the Λ for the reactions K − p → Λπ 0 , Λη , Λη ′ at 4.2 GeV/ c have been measured. The reaction K − p → Λη exhibits a pronounced dip around − t ∼0.5 ( GeV / c ) 2 and all three reactions show a significant backward peaking (− u < 1.0 (GeV/ c ) 2 ). The Λ polarization in the reaction K − p → Λπ 0 is measured to be significantly different from zero throughout most of the available t -range. Forward cross sections enable a determination of R T , the ratio of singlet/octet coupling η 1 KK ∗∗ η 8 KK ∗∗ . Backward cross sections are utilized to estimate the effective η-nucleon coupling constant g η NN 2 over the − u range 0–1.5 ( GeV /c) 2 .

15 data tables
Table 1

QUOTED VALUES OF THE KINEMATIC LOWER LIMITS OF -T AND -U.

Table 2

Axis error includes +- 5/5 contribution.

Table 3

Axis error includes +- 5/5 contribution.

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