Search results for "jet fragmentation"
showing 10 items of 169 documents
Energy-energy correlations in hadronic final states from Z0 decays
1990
We have studied the energy-energy angular correlations in hadronic final states from Z0 decay using the DELPHI detector at LEP. From a comparison with Monte Carlo calculations based on the exact second order QCD matrix element and string fragmentation we find that Λ(5)/MS = 104-20 +25 (stat.)-20 +25(syst.)-00 +30(theor.) MeV, which corresponds to αs(91 GeV) = 0.106± 0.003 (stat.)±0.003(syst.)-0.000 +0.003(theor.). The theoretical error stems from different choices for the renormalization scale of αs. In the Monte Carlo simulation the scale of αs as well as the fragmentation parameters have been optimized to described reasonably well all aspects of multihadron production.
Measurement of correlations between pions from different W's in e+e- → W+W- events
1997
Correlations between pions from different W's in e(+)e(-) --> W+W- events are studied using data collected by the DELPHI detector at LEP running at a centre-of-mass energy of 172 GeV in 1996. At the present level of statistics, no enhancement of the correlation function above that expected from a pair of uncorrelated W's is observed at small values of the four-momentum difference of the pions. (C) 1997 Published by Elsevier Science B.V.
A measurement of the mean lifetimes of charged and neutral B-hadrons
1993
The decays of B-hadrons have been reconstructed using the charged particles recorded in the DELPHI silicon microstrip detector. The sum of the charges of the secondaries determines the charge of the B-hadron parent. Some 232 114 multihadronic Z0 decays recorded during the 1991 run of LEP at centre-of-mass energies between 88.2 GeV and 94.2 GeV yield 253 B-hadron candidates with well-measured charge. From these the mean lifetimes of neutral and charged B-hadrons are found to be 1.44 +/- 0.21(stat.) +/- 0.14(syst.) ps and 1.56 +/- 0.19(stat.) +/- 0.13(syst.) ps respectively. The ratio of their lifetimes is 1.09(-0.23)+0.28 (Stat.) +/- 0.11 (syst.). Under some assumptions on the abundance and …
Limits on the production of scalar leptoquarks from $Z^0$ decays at LEP
1993
A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equ…
First evidence for a charm radial excitation, D
1998
Using D*+ mesons exclusively reconstructed in the DELPHI detector at LEP, an excess of 66 +/- 14(stat.) events is observed in the D(*+)pi(+)pi(-) final state with a mass of 2637 +/- 2(stat.) +/- 6(syst.) MeV/c(2) and a full width smaller than 15 MeV/c(2) (95% C.L.). This signal is compatible with the expected decay of a radially excited D*' (J(P) = 1(-))meson. (C) 1998 Published by Elsevier Science B.V. All rights reserved.
J / psi production in the hadronic decays of the Z.
1994
Abstract: J/psi mesons have been reconstructed from their decay to mu(+)mu(-) and e(+)e(-), using the data collected by the DELPHI experiment during 1991 and 1992 at the LEP collider. From about 1 million hadronic Z decays 153 +/- 17 J/psi were found, 5.4 +/- 2.3 psi' were obtained in the channel J/psi(--> mu(+)mu(-))pi(+)pi(-) and 6.4 +/- 2.7 chi(c) in the channel J/psi(--> mu(+)mu(-))gamma. As the dominant source of J/psi mesons is from b quarks, the following branching ratios: Br(b-->J/psi X) = (1.12 +/- 0.12 (stat.) +/- 0.10 (syst.))%, Br(b --> psi' X) = (0.48 +/- 0.22 (stat.) +/- 0.10 (syst.))%, Br(b-->chi(cl) X) = (1.4 +/- 0.6 (stat.)(-0.2)(+0.4) (syst.))% were measured. From the prop…
Improved measurements of cross sections and asymmetries at the Z0 resonance
1994
During the 1992 running period of the LEP e+e- collider, the DELPHI experiment accumulated approximately 24 pb-1 of data at the Z0 peak. The decays into hadrons and charged leptons have been analysed to give values for the cross sections and leptonic forward-backward asymmetries which are significantly improved with respect to those previously published by the DELPHI collaboration. Incorporating these new data, more precise values for the Z0 resonance parameters are obtained from model-independent fits. The results are interpreted within the framework of the Standard Model, yielding for the top quark mass m(t) = 157(-48)+36(expt.)-20(+19)(Higgs) GeV, and for the effective mixing angle sin2 …
"Table 45" of "Measurement of jet fragmentation in Pb+Pb and $pp$ collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ATLAS detector"
2020
The D(pT) distributions in different centrality intervals in PbPb and in pp for 158.49 < pTjet < 199.53 and 0.8 < eta < 1.2.
"Table 57" of "Measurement of jet fragmentation in Pb+Pb and $pp$ collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ATLAS detector"
2020
The D(pT) distributions in different centrality intervals in PbPb and in pp for 199.53 < pTjet < 251.19 and 0.3 < eta < 0.8.
"Table 81" of "Measurement of jet fragmentation in Pb+Pb and $pp$ collisions at $\sqrt{s_{NN}} = 5.02$ TeV with the ATLAS detector"
2019
The D(pT) distributions in different centrality intervals in PbPb and in pp for 251.19 < pTjet < 316.22 and 1.2 < eta < 2.1.