Spin alignment of leading K*(892)0 mesons in hadronic Z0 decays.

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Phys.Lett.B 412 (1997) 210-224, 1997.
Inspire Record 447146 DOI 10.17182/hepdata.47440

Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The values of the real part of the off-diagonal element rho_1-1 are negative at large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x_p range. The K^*0 fragmentation function has also been measured and the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per hadronic Z^0 decay.

4 data tables

Inclusive K*= cross section.

Helicity density matrices elemnts.

Ratios of helicity density matrices elements.

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Measurement of the t anti-t production cross-section in p anti-p collisions at S**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 80 (1998) 2773-2778, 1998.
Inspire Record 449604 DOI 10.17182/hepdata.42178

We present a measurement of the t-tbar cross section in p-pbar collisions at sqrt(s)=1.8 TeV using an integrated luminosity of 109 pb-1 collected with the Collider Detector at Fermilab. The measurement uses t-tbar decays into final states which contain one or two high transverse momentum leptons and multiple jets, and final states which contain only jets. Using acceptances appropriate for a top quark mass of 175 GeV/c^2, we find sigma(t-tbar)=7.6 (+1.8 -1.5) pb .

1 data table

SVX (second vertex) and SLT (second lepton) denote different method of b-tagging. Errors shown are statistical and systematical combined in quadrature.


A measurement of the b anti-b cross section in 800-GeV/c proton silicon interactions.

The E771 collaboration Alexopoulos, T. ; Antoniazzi, L. ; Arenton, M. ; et al.
Phys.Rev.Lett. 82 (1999) 41-44, 1999.
Inspire Record 447430 DOI 10.17182/hepdata.42183

The cross section for bb¯ production in 800GeV/c pN interactions has been measured in Fermilab experiment E771 to be 43−17+27(stat)−7+7(syst)nb per nucleon from the observation of events in which both the b and the b¯ decay semimuonically or a B decays into a J/ψ followed by J/ψ→μ+μ−.

1 data table

No description provided.


Studies of gauge boson pair production and trilinear couplings

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.D 56 (1997) 6742-6778, 1997.
Inspire Record 441947 DOI 10.17182/hepdata.42213

The gauge boson pair production processes Wg, WW, WZ, and Zg were studied using pbarp collisions corresponding to an integrated luminosity of ~14 pb-1 at a center-of-mass energy of sqrt(s) = 1.8 TeV. Analysis of Wg prod with subsequent W boson decay to lv (l=e,mu) is reported, including a fit to the pT spectrum of the photons which leads to limits on anomalous WWg couplings. A search for WW prod with subsequent decay to l-lbar-v-vbar (l=e,mu) is presented leading to an upper limit on the WW prod cross section and limits on anomalous WWg and WWZ couplings. A search for high pT W bosons in WW and WZ prod is described, where one W boson decays to an ev and the second W boson or the Z boson decays to two jets. A maximum likelihood fit to the pT spectrum of W bosons resulted in limits on anomalous WWg and WWZ couplings. A combined fit to the three data sets which provided the tightest limits on anomalous WWg and WWZ couplings is also described. Limits on anomalous ZZg and Zgg couplings are presented from an analysis of the photon ET spectrum in Zg events in the decay channels (ee, mu-mu, and v-vbar) of the Z boson.

1 data table

CONST(NAME=SCALE) is the model parameter, used in the modification of the couplings as follows: h = hi0/(1 + M(gamma Z)**2/CONT(NAME=SCALE)**2)**n. See article for details.


Measurement of the quark and gluon fragmentation functions in Z0 hadronic decays.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 6 (1999) 19-33, 1999.
Inspire Record 448370 DOI 10.17182/hepdata.47405

The transverse, longitudinal and asymmetric components of the fragmentation function are measured from the inclusive charged particles produced in$e^+e^-$collisi

9 data tables

Transverse component of the differential cross section.

Longitudinal component of the differential cross section.

Asymmetric component of the differential cross section.

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Measurement of the differential cross-section for events with large total transverse energy in p anti-p collisions at s**(1/2) = 1.8-Tev

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 80 (1998) 3461-3466, 1998.
Inspire Record 448075 DOI 10.17182/hepdata.42179

We present a measurement of the differential cross section dσ/dΣETjet for the production of multijet events in pp¯ collisions where the sum is over all jets with transverse energy ETjet>ETmin. The measured cross section for events with ΣETjet>320GeV is compared to O(αs3) perturbative QCD predictions and QCD parton shower Monte Carlo predictions. The agreement between the O(αs3) predicted and observed event rates is reasonable for ETmin=100GeV, but poorer for ETmin=20GeV.

2 data tables

The ET shown here (unless specified otherwise) is the sum of all the jets' individual ETs. All jets are required to have the absolute values of their pseudorapidity < 4.2 and data are given for two different minimum ET cut-offs.. The errors given are statistical only.

Integrated cross sections. Again ET is the sum of the individual ETs of thejets.


Measurement of f(c --> D*+ X), f(b --> D*+ X) and Gamma(c anti-c)/Gamma(had) using D*+- mesons.

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Eur.Phys.J.C 1 (1998) 439-459, 1998.
Inspire Record 447145 DOI 10.17182/hepdata.47409

The production rates of D^*+/- mesons in charm and bottom events at centre-of-mass energies of about 91 GeV and the partial width of primary cc(bar) pairs in hadronic Z^0 decays have been measured at LEP using almost 4.4 million hadronic Z^0 decays collected with the OPAL detector between 1990 and 1995. Using a combination of several charm quark tagging methods based on fully and partially reconstructed D^*+/- mesons, and a bottom tag based on identified muons and electrons, the hadronisation fractions of charm and bottom quarks into D^*+/- mesons have been found to be: f(b -> D^*+ X) = 0.173 +/- 0.016 +/- 0.012 and f(c -> D^*+ X) = 0.222 +/- 0.014 +/- 0.014 The fraction of cc(bar) events in hadronic Z^0 decays, Gamma_cc(bar)/Gamma_had = Gamma(Z^0 -> cc(bar))/Gamma(Z^0 -> hadrons), is determined to be Gamma_cc(bar)/Gamma_had = 0.180 +/- 0.011 +/- 0.012 +/- 0.006 In all cases the first error is statistical, and the second one systematic. The last error quoted for Gamma_cc(bar)/Gamma_had is due to external branching ratios.

3 data tables

No description provided.

No description provided.

The second syst. errors results due to extranal branching ratios. Charge conjugated states are implied. FD is considered as a quark fragmentation fraction. Sqrt(s(E+ E-)) = 91.2 GeV.


Measurement of the average lifetime of b hadrons in Z decays

The L3 collaboration Acciarri, M. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 416 (1998) 220-232, 1998.
Inspire Record 449593 DOI 10.17182/hepdata.47380

We present a measurement of the average b-hadron lifetime τ b at the e + e − collider LEP. Using hadronic Z decays collected in the period from 1991 to 1994, two independent analyses have been performed. In the first one, the b-decay position is reconstructed as a secondary vertex of hadronic b-decay particles. The second analysis is an updated measurement of τ b using the impact parameter of leptons with high momentum and high transverse momentum. The combined result is τ b =[1549±9 (stat) ±15 (syst)] fs . In addition, we measure the average charged b-decay multiplicity 〈 n b 〉 and the normalized average b-energy 〈 x E 〉 b at LEP to be 〈n b 〉=4.90±0.04 (stat)±0.11 (syst), 〈x E 〉 b =0.709±0.004 (stat+syst).

2 data tables

No description provided.

No description provided.


Search for supersymmetry in the photon(s) plus missing energy channels at s**(1/2) = 161-GeV and 172-GeV.

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 420 (1998) 127-139, 1998.
Inspire Record 449077 DOI 10.17182/hepdata.47381

Searches for supersymmetric particles in channels with one or more photons and missing energy have been performed with data collected by the ALEPH detector at LEP. The data consist of 11.1 pb-1 at $\sqrt{s} = 161 GeV$, 1.1 pb-1 at 170 GeV and 9.5 pb-1 at 172 GeV. The e+e- -> nunu+photon cross section is measured. The data are in good agreement with predictions based on the Standard Model, and are used to set upper limits on the cross sections for anomalous photon production. These limits are compared to two different SUSY models and used to set limits on the neutralino mass. A limit of 71 GeV/c^2 at 95% C.L. is set on the mass of the lightest neutralino ($\tau_{\chi_{1}^{0}} \leq $ 3 ns) for the gauge-mediated supersymmetry breaking and LNZ models.

1 data table

No description provided.


Search for the pentaquark via the P(anti-c s)0 --> Phi pi p decay.

The E791 collaboration Aitala, E.M. ; Amato, S. ; Anjos, J.C. ; et al.
Phys.Rev.Lett. 81 (1998) 44-48, 1998.
Inspire Record 448379 DOI 10.17182/hepdata.42196

We report results of the first search for the pentaquark P_{{c bar}s} which is predicted to be a doublet of states: P^0_{{c bar}s}=({c bar} s u u d) and P^-_{{c bar}s}=({c bar} s d d u). A search was made for the decay P^0_{{c bar}s} --> phi,pi,p in data from Fermilab experiment E791, in which 500 GeV/c pi^- beam interacted with nuclear targets. We present upper limits at 90% confidence level for the ratio of cross section times branching fraction of this decay to that for the decay D_s --> phi,pi. The upper limits are 0.031 and 0.063 for M(P^0_{{c bar}s}) = 2.75 and 2.86 GeV/c^2, respectively, assuming a P^0_{{c bar}s} lifetime of 0.4 ps.

1 data table

The cross sections times branching ratio.