Laffaille, J.M.
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Search for new phenomena using single photon events in the DELPHI detector at LEP

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 74 (1997) 577-586, 1997.
Inspire Record 415746 DOI 10.17182/hepdata.41128

Data are presented on the reaction e+e− → γ + no other detected particle at centre-of-mass energies of 89.48, 91.26 and 93.08 GeV. The cross-section for this reaction is related directly to the number of light neutrino generations which couple to the Z° boson, and to several other possible phenomena such as the production of excited neutrinos, the production of any invisible ‘X’ particle, and the magnetic moment of the tau neutrino. Based on the observed number of single photon events, the number of light neutrinos that couple to the Z° is measured to be Nv = 2.89 ± 0.38. No evidence is found for anomalous production of energetic single photons, and upper limits at 95% confidence level are determined for excited neutrino production (BR < 4 − 8 × 10−6 depending on its mass), production of an invisible ‘X’ particle (σ, < 0.1 pb for masses below 60 GeV), and the magnetic moment of the tau neutrino (< 5.1 × 10-6 μB).

3 data tables
Table 1

No description provided.

Table 2

Limit on an anomalous magnetic moment for tau-neutrino from '1GAMMA + nothing' events. Magnetic moment in Bohr magnetons.

Table 3

Here UNSPEC is invisible particle.


Interferometry results from the CERN WA98 experiment

Rosselet, L. ; Angelis, A.L.S. ; Doenni, P. ; et al.
Nucl.Phys.A 610 (1996) 256C-263C, 1996.
Inspire Record 432737 DOI 10.17182/hepdata.36463

None

1 data table
Table 1

PRELIMINARY DATA. THE DISTRIBUTION (1/PT)*D(N)/D(PT) HAS BEEN FITTED BY A FORMULA SQRT(MT)*K1(SLOPE*MT), WHERE K1 IS THE MAKDONALD FUNCTION.


Search for the production of pionium atoms near threshold

Betker, A.C. ; Cameron, J.M. ; Jacobs, W.W. ; et al.
Phys.Rev.Lett. 77 (1996) 3510-3513, 1996.
Inspire Record 429517 DOI 10.17182/hepdata.19609

We propose a model-independent method to extract a linear combination of the s-wave π−π scattering lengths by measuring the γγ decay branching ratio for a tagged sample of π+π− atoms (pionium). In the first experimental search for an appropriate tagging reaction, we observed σtot=76±21±11pb for free pion pair production in pd→3Heπ+π− 1.0 MeV above threshold. This result suggests a pionium production cross section ≲1pb.

2 data tables
Table 1

The cross section times acceptance.

Table 2

No description provided.


Subthreshold K+ production in proton nucleus collisions

De̹bowski, M. ; Barth, R. ; Boivin, M. ; et al.
Z.Phys.A 356 (1996) 313-325, 1996.
Inspire Record 432858 DOI 10.17182/hepdata.16477

Double differential K+cross sections have been measured in p+C collisions at 1.2, 1.5 and 2.5 GeV beam energy and in p+Pb collisions at 1.2 and 1.5 GeV. The K+ spectrum taken at 2.5 GeV can be reproduced quantitatively by a model calculation which takes into account first chance proton-nucleon collisions and internal momentum with energy distribution of nucleons according to the spectral function. At 1.2 and 1.5 GeV beam energy the K+ data excess significantly the model predictions for first chance collisions. When taking secondary processes into account the results of the calculations are in much better agreement with the data.

5 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

More…

Precise pion electroproduction in the p (e, e-prime pi+) n reaction at W = 1125-MeV

Blomqvist, K.I. ; Boeglin, W.U. ; Böhm, R. ; et al.
Z.Phys.A 353 (1996) 415-421, 1996.
Inspire Record 428951 DOI 10.17182/hepdata.16502

The reactione+p →> e+π++n at c.m. energyW=1125MeV and momentum transfer Q2=0.117GeV2/c2 has been measured. The transverse and longitudinal structure functions have been separated by varying the polarization of the virtual photon (Rosenbluth plot) with a 3 to 4% error. In addition the longitudinal-transverse interference term has been determined measuring the right-left asymmetry with an accuracy of 3%. The experimental data are compared to model calculations, and the sensitivity of the results to the axial and pion formfactors is discussed.

6 data tables
Table 1

Angle PHI(P=4) is the angle between the scattering plane (defined by 1 and 3 particles) and the reaction plane (defined by 4 and 5 particles).

Table 2

Angle PHI(P=4) is the angle between the scattering plane (defined by 1 and 3 particles) and the reaction plane (defined by 4 and 5 particles).

Table 3

Angle PHI(P=4) is the angle between the scattering plane (defined by 1 and 3 particles) and the reaction plane (defined by 4 and 5 particles).

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Measurement of the B(d)0 oscillation frequency using kaons, leptons and jet charge

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 72 (1996) 17-30, 1996.
Inspire Record 415900 DOI 10.17182/hepdata.47784

A measurement of the mass difference,Δm d , between the two physical B d

1 data table
Table 1

No description provided.


Production of SIGMA0 and OMEGA- in Z decays

The DELPHI collaboration Adam, W. ; Adye, T. ; Agasi, E. ; et al.
Z.Phys.C 70 (1996) 371-382, 1996.
Inspire Record 416098 DOI 10.17182/hepdata.47799

None

3 data tables
Table 1

Statistical error only.

Table 2

No description provided.

Table 3

No description provided.


Charged particle multiplicity in e+ e-interactions at s**(1/2) = 130-GeV

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 372 (1996) 172-180, 1996.
Inspire Record 415744 DOI 10.17182/hepdata.47831

From the data collected by DELPHI at LEP in autumn 1995, the multiplicity of charged particles at a hadronic energy of 130 GeV has been measured to be 〈 n ch 〉 = 23.84 ± 0.51 (stat) ± 0.52 (syst). When compared to lower energy data, the value measured is consistent with the evolution predicted by QCD with corrections at next-to-leading order, for a value α s (130 GeV) = 0.105 ± 0.003 (stat) ± 0.008 (syst).

1 data table
Table 1

No description provided.


Determination of sin**2 theta(w)(eff) using jet charge measurements in hadronic Z decays

The ALEPH collaboration Buskulic, D. ; De Bonis, I. ; Decamp, D. ; et al.
Z.Phys.C 71 (1996) 357-378, 1996.
Inspire Record 416137 DOI 10.17182/hepdata.47832

None

1 data table
Table 1

The first sytematic error is due to the experimental uncertainties, whilst the second is due to the uncertainties in the quark charge separations.


rivet Analysis
Measurement of Lambda polarization from Z decays

The ALEPH collaboration Buskulic, D. ; De Bonis, I. ; Decamp, D. ; et al.
Phys.Lett.B 374 (1996) 319-330, 1996.
Inspire Record 415745 DOI 10.17182/hepdata.47830

The polarization of Λ baryons from Z decays is studied with the Aleph apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Λ polarization is P L Λ = −0.32 ± 0.07 for z = p p beam > 0.3 . This agrees with the prediction of −0.39 ± 0.08 from the standard model and the constituent quark model, where the error is due to uncertainties in the mechanism for Λ production. The observed Λ polarization is diluted with respect to the primary s quark polarization by Λ baryons without a primary s quark. Measurements of the Λ forward-backward asymmetry and of the correlation between back-to-back Λ Λ pairs are used to check this dilution. In addition the transverse Λ polarization is measured. An indication of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrust axis and the Λ direction.

3 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.