HEPData Search

Experimental evidence for the existence of orbitally excited B meson states is presented in an analysis of the Bπ and B ∗ π distribution of Q = m(B ∗∗ ) − m(B (∗) ) − m(π) using Z 0 decay data taken with the DELPHI detector at LEP. The mean Q-value of the decays B ∗∗ → B (∗) π is measured to be 284 ± 5 (stat.) ± 15 (syst.) MeV/c 2 , and the Gaussian width of the signal is 79 ± 5 (stat.) ± 8 (syst.) MeV/c 2 . This signal can be described as a single resonance of mass m = 5732 ± 5 (stat.) ± 20 (syst.) MeV/c 2 and full width Γ = 145 ± 28 MeV/c 2 . The observed shape is also consistent with the production of several broad and narrow states as predicted by the quark model and partly observed in the D-meson sector. The production rate of B ∗∗ per b-jet is found to be 0.27 ± 0.02 (stat.) ± 0.06 (syst.).

1 data table

Table 1

No description provided.

Search for promptly produced heavy quarkonium states in hadronic Z decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Z.Phys.C 69 (1996) 575-584, 1996.

Inspire Record 401612 DOI 10.17182/hepdata.48135

A search has been made for direct production of heavy quarkonium states in more than 3 million hadronic Z0 decays in the 1991–1994 DELPHI data. Prompt J/ψ, ψ(2S) and Υ candidates have been searched for through their leptonic decay modes using criteria based on the kinematics and decay vertex positions. New upperlimits are set at the 90% confidence level for Br(Z0 → (QQ) X)/Br (Z0 → hadrons) for various strong production mechanisms of J/ψ and Υ these range down to 0.9 × 10−4. The limits are set in the presence of a small excess (∼ 1% statistical probability of a background fluctuation) in the sum of candidates from prompt J/ψ, ψ(2S), Υ(1S),Υ(2S) and Υ(3S) relative to the estimated background.

2 data tables

Table 1

The analysis of hadrons (from X) provides to distinguish of the various decay modes of Z-boson (see text).

Table 2

No description provided.

rivet Analysis
B* production in Z decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Z.Phys.C 68 (1995) 353-362, 1995.

Inspire Record 395026 DOI 10.17182/hepdata.52359

None

2 data tables

Table 1

No description provided.

Table 2

No description provided.

rivet Analysis
Measurement of inclusive pi0 production in hadronic Z0 decays

The DELPHI collaboration Adam, W. ; Adye, T. ; Agasi, E. ; et al.

Z.Phys.C 69 (1996) 561-574, 1996.

Inspire Record 401100 DOI 10.17182/hepdata.48063

An analysis is presented of inclusive π0 production in Z0 decays measured with the DELPHI detector. At low energies, π0 decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to $x_p={2cdot p≪/{sqrt s}=0.75}$) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for qq̅ and bb̅ events. The number of π0’s per hadronic Z0 event is $N(≪^0)/Z_{had} ^0=9.2pm 0.2({⤪ stat})pm 1.0 ({⤪ syst})$ and for bb̅ events the number of π0’s is ${⤪ N}(≪^0)/{⤪ b⋏r b}=10.1pm 0.4({⤪ stat})pm 1.1 ({⤪ syst})$. The ratio of the number of π0’s in bb̅ events to hadronic Z0 events is less affected by the systematic errors and is found to be 1.09 ±0.05 ±0.01. The measured π0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the $xi_{⤪ p}={⤪ ln}(1/{⤪ x_p})$ distribution is $xi_p^{⋆ar}=3.90_{-0.14}^{+0.24}.$ The average number of π0’s from the decay of primary B hadrons is found to be N(B → π0X)/B hadron = 2.78 ± 0.15(stat) ± 0.60(syst).

4 data tables

Table 1

Differential cross section for all events.

Table 2

Mean PI0 multiplicity extrapolated below 0.011 with JETSET 7.3.

Table 3

Differential cross section for the enriched (b bbar) data set.

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rivet Analysis
Measurement of Delta++ (1232) production in hadronic Z decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Phys.Lett.B 361 (1995) 207-220, 1995.

Inspire Record 399737 DOI 10.17182/hepdata.48095

A measurement of the Δ ++ (1232) inclusive production in hadronic decays of the Z at LEP is presented, based on 1.3 million hadronic events collected by the DELPHI detector in the 1994 LEP running period. The DELPHI ring imaging Cherenkov counters are used for identifying hadrons. The average Δ ++ (1232) multiplicity per hadronic event is 0.079 ± 0.015 which is more than a factor of two below the JETSET, HERWIG and UCLA model predictions. It agrees with a recently proposed universal mass dependence of particle production rates in e + e − annihilations.

2 data tables

Table 1

Differential DELTA(1232)++ cross section. Errors are combined statistics and systematics.

Table 2

Mean multiplicities. Extrapolation to full x range using a combination of JETSET, HERWIG and UCLA models. The second systematic error comes from the uncertainty in the extrapolation.

Study of prompt photon production in hadronic Z0 decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Z.Phys.C 69 (1995) 1-14, 1995.

Inspire Record 397391 DOI 10.17182/hepdata.48136

None

3 data tables

Table 1

Rates for gamma + 1 jet.

Table 2

Rates for gamma + 2 jet.

Table 3

Rates for gamma + 3 jet.

A Measurement of the tau leptonic branching fractions

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Phys.Lett.B 357 (1995) 715-724, 1995.

Inspire Record 398321 DOI 10.17182/hepdata.48138

A sample of 25000 Z 0 → τ + τ − events collected by the DELPHI experiment at LEP in 1991 and 1992 is used to measure the leptonic branching fractions of the τ lepton. The results are B(τ → eν ν ) = (17.51 ± 0.39) % and B(τ → μν ν ) = (17.02 ± 0.31) %. The ratio of the muon and electron couplings to the weak charged current is measured to be g μ g e = 1.000 ± 0.013 , satisfying e-μ universality. The leptonic branching fraction corrected to the value for a massless lepton, assuming e-μ universality, is found to be B(τ → lν ν ) = (17.50 ± 0.25) %.

3 data tables

Table 1

Axis error includes +- 0.23/0.23 contribution (Data statistics).

Table 2

Axis error includes +- 0.19/0.19 contribution (Data statistics).

Table 3

Combined from the two branching fractions above. E-MU universality assumed.

Production of charged particles, K0(s), K+-, p and Lambda in Z --> b anti-b events and in the decay of b hadrons

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.

Phys.Lett.B 347 (1995) 447-466, 1995.

Inspire Record 392257 DOI 10.17182/hepdata.48180

A sample of events enriched in bb̄ quark pairs was selected in the data recorded by the DELPHI experiment at LEP during 1992 and 1993, by the presence of secondary decay vertices from short-lived particles. Using this sample, the average multiplicities of K s 0 , K ± , p(p̄), Λ( Λ ) and of charged particles in bb̄ events have been measured, distinguishing the component from fragmentation and the component coming from the decay of b-hadrons. The measurement of the average charge multiplicity in bb̄ events was used to compute the mean fractional beam energy carried by the primary b-hadron, and the difference in charged particle multiplicity between bb̄ events and light quark (uū, dd̄, ss̄) events.

9 data tables

Table 1

Event multiplicity in bottom events.

Table 2

Differential cross section for charged particles in BOTTOM tagged hemispheres.

Table 3

Differential cross section for charged particles in untagged hemispheres.