First observation of the Sigma/c*+ baryon and a new measurement of the Sigma/c+ mass.

The CLEO collaboration Ammar, R. ; Bean, A. ; Besson, D. ; et al.
Phys.Rev.Lett. 86 (2001) 1167-1170, 2001.
Inspire Record 530545 DOI 10.17182/hepdata.47310

Using data recorded with the CLEO II and CLEO II.V detector configurations at the Cornell Electron Storage Rings, we report the first observation and mass measurement of the $\Sigma_c^{*+}$ charmed baryon, and an updated measurement of the mass of the $\Sigma_c^+$ baryon. We find $M(\Sigma_c^{*+})-M(\Lambda_c^+)$= 231.0 +- 1.1 +- 2.0 MeV, and $M(\Sigma_c^{+})-M(\Lambda_c^+)$= 166.4 +- 0.2 +- 0.3 MeV, where the errors are statistical and systematic respectively.

1 data table

No description provided.


Production rates of b anti-b quark pairs from gluons and b anti-b b anti-b events in hadronic Z0 decays.

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Ainsley, C. ; et al.
Eur.Phys.J.C 18 (2001) 447-460, 2001.
Inspire Record 535059 DOI 10.17182/hepdata.49875

The rates are measured per hadronic Z decay for gluon splitting to bb(bar) quark pairs, g_bb, and of events containing two bb(bar) quark pairs, g_4b, using a sample of four-jet events selected from data collected with the OPAL detector. Events with an enhanced signal of gluon splitting to bb(bar) quarks are selected if two of the jets are close in phase-space and contain detached secondary vertices. For the event sample containing two bb(bar) quark pairs, three of the four jets are required to have a significantly detached secondary vertex. Information from the event topology is combined in a likelihood fit to extract the values of g_bb and g_4b, namely g_bb = (3.07 +- 0.53(stat) +- 0.97(syst))x10^-3 g_4b = (0.36 +- 0.17(stat) +- 0.27(syst))x10^-3

1 data table

No description provided.


Measurement of the probability of gluon splitting into charmed quarks in hadronic Z decays

The L3 collaboration Acciarri, M. ; Achard, P. ; Adriani, O. ; et al.
Phys.Lett.B 476 (2000) 243-255, 2000.
Inspire Record 510061 DOI 10.17182/hepdata.49044

We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%.

1 data table

No description provided.


A precision measurement of nuclear muon capture on He-3.

Ackerbauer, P. ; Balin, D.V. ; Baturin, V.M. ; et al.
Phys.Lett.B 417 (1998) 224-232, 1998.
Inspire Record 447785 DOI 10.17182/hepdata.28264

The muon capture rate in the reaction mu- 3He -> nu + 3H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the mu-3He atom is (1496.0 +- 4.0) s^-1. This result confirms the PCAC prediction for the pseudoscalar form factors of the 3He-3H system and the nucleon.

1 data table

Here CONST is defined as follows: CONST = lambda0/K/(1-e), where lambda0 = 0.45516E6 1/sec is the decay rate of MU, e=7.18% is the total correction factor and K is the prescaling factor of the muon trigger (from 500 till 2000). First reaction corresponds to detected tritons, while the second one describes stopped muons not followed by muon capture. The error is the combination of statistical and systematic errors.


Study of vector mesons in dimuon production in a large kinematic region in p W and S W interactions at 200-GeV/c/nucleon.

The HELIOS-3 collaboration Angelis, A.L.S. ; Antos, J. ; Beaulieu, M. ; et al.
Eur.Phys.J.C 5 (1998) 63-75, 1998.
Inspire Record 448978 DOI 10.17182/hepdata.47370

Results are presented on p + ω,ø and J/ψ production in p-W and 32S-W interactions at 200GeV/c/nucleon measured via the dimuon decay in a large kinematic region. The data are normalized to the charged particle multiplicity in the same rapidity interval. They have been collected using the HELIOS/3 muon spectrometer at the CERN SPS. The ratio Bσø/ (Bσρ + Bσω), where B is the relevant resonance µµ branching fraction, increases between proton and sulphur projectiles, and is somewhat enhanced going from peripheral to central S-W interactions. This results from an increase in the number of produced ø’s per charged particle. The ratio is measured in different intervals of pt and rapidity. It is not clearly dependent on pt, but is larger at higher rapidities. J/Ψ production, likewise normalized to charged multiplicity, is significantly lower in S-W compared to p-W interactions.

8 data tables

Multiplicity dependence of the ratios for proton beam.

Multiplicity dependence of the ratios for sulphur beam.

No description provided.

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Dijet production by color-singlet exchange at the Fermilab Tevatron

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 80 (1998) 1156-1161, 1998.
Inspire Record 447619 DOI 10.17182/hepdata.42182

We report a new measurement of dijet production by color-singlet exchange in pp¯ collisions at s=1.8TeV at the Fermilab Tevatron. In a sample of events with two jets of transverse energy ETjet>20GeV, pseudorapidity in the range 1.8<|ηjet|<3.5, and η1η2<0, we find that a fraction R=[1.13±0.12(stat)±0.11(syst)]% has a pseudorapidity gap within |η|<1 between the jets that can be attributed to color-singlet exchnage. The fraction R shows no significant dependence on ETjet or on the pseudorapidity separation between the jets.

1 data table

Q=SS and Q=OS means same-side and opposite-side events.


Measurement of the multiplicity of gluons splitting to bottom quark pairs in hadronic Z0 decays.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 405 (1997) 202-214, 1997.
Inspire Record 442880 DOI 10.17182/hepdata.47486

An inclusive measurement of the average multiplicity of b b pairs from gluons, g b b , in hadronic Z 0 events collected by the DELPHI experiment at LEP, is presented. A counting technique, based on jet b -tagging in 4-jet events, has been used. Looking for secondary bottom production in events with production of any primary flavour, by requiring two b -tagged jets in well defined topological configurations, gave g b b = (0.21 ± 0.11 ( stat ) ± 0.09 ( syst ))% . This result was checked with a different method designed to select events with four b quarks in the final state. Agreement within the errors was found.

1 data table

No description provided.


Quark and gluon jet properties in symmetric three-jet events

The ALEPH collaboration Buskulic, D. ; Casper, D. ; De Bonis, I. ; et al.
Phys.Lett.B 384 (1996) 96008490 353-364, 1996.
Inspire Record 404562 DOI 10.17182/hepdata.48015

Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet configurations from hadronic Z decays observed by the ALEPH detector. Jets are defined using the Durham algorithm. Gluon jets are identified using an anti-tag on b jets, based on a track impact parameter method. The comparison of gluon and mixed flavour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity, Evidence is presented which shows that the corresponding differences between gluon and b jets are significantly smaller. In a statistically limited comparison the multiplicity in c jets was found to be comparable with that observed for the jets of mixed quark flavour.

2 data tables

B-jets are identified with the lepton-tag analysis.

The same kinematics as in the table 1.


Jet production via strongly interacting color singlet exchange in p anti-p collisions

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.Lett. 76 (1996) 734-739, 1996.
Inspire Record 400107 DOI 10.17182/hepdata.42348

A study of the particle multiplicity between jets with large rapidity separation has been performed using the D\O\ detector at the Fermilab Tevatron $p\bar{p}$ Collider operating at $\sqrt{s}=1.8$\,TeV. A significant excess of low-multiplicity events is observed above the expectation for color-exchange processes. The measured fractional excess is $1.07 \pm 0.10({\rm stat})~{ + 0.25}_{- 0.13}({\rm syst})\%$, which is consistent with a strongly-interacting color-singlet (colorless) exchange process and cannot be explained by electroweak exchange alone. A lower limit of $0.80\%$ (95\% C.L.) is obtained on the fraction of dijet events with color-singlet exchange, independent of the rapidity gap survival probability.

1 data table

'Opposite-side' jets with a large pseudorapidity separation. A cone algorithm with radius R = sqrt(d(etarap)**2+d(phi)**2)=0.7 is used for jet funding. Double negative binomial distribution (NBD) is used to parametrize the color-exchange component of the opposite-side multiplicity distribution betweeb jets. A result of extrapolation to the zero multiplicity point. Quoted systematic error is a result of combining in quadrature of the systematic errors described above.


Measurement of the multiplicity of charm quark pairs from gluons in hadronic Z0 decays

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett.B 353 (1995) 595-605, 1995.
Inspire Record 395451 DOI 10.17182/hepdata.48158

We have measured the multiplicity of charm quark pairs arising from gluon splitting in a sample of about 3.5 million hadronic Z 0 decays. By selecting a 3-jet event topology and tagging charmed hadrons in the lowest energy jet using leptons, we established a signature of heavy quark pair production from gluons. The average number of gluons splitting into a c c pair per hadronic event was measured to be n g→c c =(2.27±0.28±0.41) × 10 −2 .

1 data table

Axis error includes +- 8.4/8.4 contribution (Total generator error for the electron channel due to the uncertainties in parameters of Peterson model of fragmentation, LAMBDA_QCD, ALPHA_S, Lund fragmentation parameters and lepton decay model).