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rivet Analysis
An Experimental study of the process gamma gamma ---> pi+ pi-

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Field, J.H. ; et al.

Z.Phys.C 56 (1992) 381-390, 1992.

Inspire Record 345437 DOI 10.17182/hepdata.14534

Using the CELLO detector, we have measured cross sections for the processγγ→π+π− in the mass range 0.75–1.9 GeV/c2. A partial wave fit to the data indicates the presence of a sizeableS-wave amplitude with signs of resonant behaviour. Values for the γγ width of thef2(1270) are given, showing the model-dependence of this quantity. At higher dipion masses, the model of Brodsky and Lepage is found to give an order of magnitude description of the data.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Meson production in p + U, O + U and S + U interactions at 200-GeV/nucleon.

The NA38 collaboration Abreu, M.C. ; Baglin, C. ; Baldisseri, A. ; et al.

Z.Phys.C 55 (1992) 365-371, 1992.

Inspire Record 344266 DOI 10.17182/hepdata.14583

Meson production in proton, oxygen and sulphur interactions with uranium targets at 200 GeV/nucleon is studied. We measure the inclusive meson cross-section d σ/dPT2 and its evolution fromp+U to S+U. The cross-section fitted with an exponential gives an inverse slopePT0 of the order of 210 MeV/c. As a function of the neutral transverse energy,PT0 values show a slight rise followed by a plateau. The normalized difference (σ+−σ−)/σ− between positive and negative meson cross-sections is found to increase withET.

6 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Polarization of Lambda hyperons produced by the quasifree (pi+, K+) reaction on C-12

Ajimura, S. ; Ejiri, H. ; Higashi, A. ; et al.

Phys.Rev.Lett. 68 (1992) 2137-2140, 1992.

Inspire Record 338084 DOI 10.17182/hepdata.19866

The polarization of quasifree Λ hyperons produced by the (π+K+) reaction on C12 and on the deuteron was measured for the first time. The asymmetry of pions from weak decay of the Λ hyperon was used to determine the polarization. The polarization for the deuterium target was found to be consistent with that for the elementary n(π+,K+)Λ reaction. The polarization of the Λ produced by the quasifree process from C12 is consistent with that for the elementary reaction, which demonstrates that the spin characteristics of the elementary reaction are not modified by the nuclear medium.

1 data table

Table 1

No description provided.

Measurements at 0-degrees of negatively charged particles and anti-nuclei produced in collision of 14.6-A/GeV/c Si on Al, Cu, and Au targets

Aoki, M. ; Beatty, J. ; Beavis, D. ; et al.

Phys.Rev.Lett. 69 (1992) 2345-2348, 1992.

Inspire Record 344921 DOI 10.17182/hepdata.19827

We report measurements of d¯, p¯, K−, and π− produced at 0° in collisions of 14.6A GeV/c Si28 on Al, Cu, and Au targets. A beam-line focusing spectrometer was used to identify particles at rigidities from -2 to -8 GV. The ratio of d¯/p¯ invariant cross sections at midrapidity (y=1.7) is (1±0.7)×10−5, larger than expected from a calculation of dd¯ direct production but smaller than predicted by a simple coalescence model. We also report limits on the production of exotic particles.

10 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Measurement of B0 anti-B0 mixing at the Fermilab Tevatron collider

The CDF collaboration Abe, F. ; Amidei, Dante E. ; Apollinari, G. ; et al.

Phys.Rev.Lett. 67 (1991) 3351-3355, 1991.

Inspire Record 332810 DOI 10.17182/hepdata.19881

The B0 B¯ 0 average mixing parameter χ has been extracted from eμ and ee events produced in pp¯ collisions at √s =1.8 TeV. In a sample of 900 eμ events, the like-sign to opposite-sign charge ratio R is measured to be 0.556±0.048(stat)−0.042+0.035(syst). In the absence of mixing, the expected value of R would be 0.23±0.06. The corresponding number for 212 ee events is 0.573±0.116(stat)±0.047(syst) with an expected nonmixing value of 0.24±0.07. The observed excess in R leads to a combined determination of χ=0.176±0.031(stat+syst) ±0.032 (model), where the last uncertainty is due to Monte Carlo modeling.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Shadowing in the muon-xenon inelastic scattering cross-section at 490-GeV

The Fermilab E665 collaboration Adams, M.R. ; Aid, S. ; Anthony, P.L. ; et al.

Phys.Lett.B 287 (1992) 375-380, 1992.

Inspire Record 341389 DOI 10.17182/hepdata.29153

Inelastic scattering of 490 GeV μ + from deuterium and xenon nuclei has been studied for x Bj > s .001. The ratio of the xenon/deuterium cross section per nucleon is observed to vary with x Bj , with a depletion in the kinematic range 0.001 < x Bj < 0.025 which exhibits no significant Q 2 dependence. An electromagnetic calorimeter was used to verify the radiative corrections.

2 data tables

Table 1

Xenon structure function parameterized as being equal to the DEUT structurefunction.

Table 2

Xenon structure function parameterized by an x-dependent shadowing factor times the DEUT structure function.

A Measurement of the B meson and b quark cross-sections at s**(1/2) = 1.8-TeV using the exclusive decay B+- ---> J / psi K+-

The CDF collaboration Abe, F. ; Amidei, Dante E. ; Apollinari, G. ; et al.

Phys.Rev.Lett. 68 (1992) 3403-3407, 1992.

Inspire Record 333080 DOI 10.17182/hepdata.19852

This letter reports the full reconstruction of B mesons through the decay chain B±→J/ψ K±, J/ψ→μ+μ−, using data obtained at the Collider Detector at Fermilab in p¯p collisions at √s =1.8 TeV. This exclusive sample, the first observed at a hadron collider, is then used to measure the B-meson cross section, from which we extract the b-quark cross section. We obtain σ=2.8±0.9 (stat) ±1.1(syst) μb for B− mesons with PT>9.0 GeV/c and rapidity ‖y‖<1.0. We obtain σ=6.1±1.9(stat) ±2.4(syst) μb, for b quarks with transverse momentum PT>11.5 GeV/c and rapidity ‖y‖<1.0.

2 data tables

Table 1

B-meson cross section.

Table 2

B-quark cross section.

Nuclear Dependence of High $X_t$ Hadron and High Tau Hadron Pair Production in p-A Interactions at $\sqrt{s}$ = 38.8 GeV

Straub, P.B. ; Jaffe, D.E. ; Glass, Henry D. ; et al.

Phys.Rev.Lett. 68 (1992) 452-455, 1992.

Inspire Record 335754 DOI 10.17182/hepdata.19847

We present a high-statistics, species-identified measurement of the W-to-Be per-nucleon cross-section ratio, RW/Be, for high-xt hadrons and high-τ h+h− pairs produced in p-A collisions at √s =38.8 GeV. The data extend to 0.62 in xt and 0.39 in √τ . For single hadrons, RW/Be peaks at pt≊5 GeV/c and decreases to ≊1 for mesons with pt>8 GeV/c. At fixed pt, RW/Be falls with √s . For symmetric pairs with √τ >0.28, RW/Be=0.84±0.02±0.07, suggesting a nuclear suppression of high-z fragmentation. RW/Be increases with pout, indicative of constituent multiple scattering.

1 data table

Table 1

No description provided.

Direct soft photon production in K+ p and pi+ p interactions at 250-GeV/c

The EHS/NA22 collaboration Botterweck, F. ; Chapkin, M.M. ; Charlet, M. ; et al.

Z.Phys.C 51 (1991) 541-548, 1991.

Inspire Record 323612 DOI 10.17182/hepdata.14936

Inclusive production of direct soft photons is studied inK+p andK+π interactions at 250 GeV/c. Total cross sections, Feynman-x and transverse momentum distributions of direct γ's are presented. The measured cross sections are several times larger than expected from QED inner bremsstrahlung, indicating the presence of an anomalous soft photon source. The model of Lichard and Van Hove, based on the “cold quark-gluon plasma” picture, agrees with the data.

5 data tables

Table 1

Results extrapolated below p(gamma) = m(pi0)/2.

Table 2

No description provided.

Table 3

No description provided.