Measurement of W pair production in e+ e- collisions at 189-GeV.

The ALEPH collaboration Barate, R. ; Decamp, D. ; Ghez, Philippe ; et al.
Phys.Lett.B 484 (2000) 205-217, 2000.
Inspire Record 527492 DOI 10.17182/hepdata.49968

The production of W-pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 174.2 pb^-1. Cross sections are given for different topologies of W decays into leptons or hadrons. Combining all final states and assuming Standard Model branching fractions, the total W-pair cross section is measured to be 15.71 +- 0.34 (stat) +- 0.18 (syst) pb. Using also the W-pair data samples collected by ALEPH at lower centre-of-mass energies, the decay branching fraction of the W boson into hadrons is measured to be BR (W > hadrons) = 66.97 +- 0.65 (stat) +- 0.32 (syst) %, allowing a determination of the CKM matrix element |V(cs)|= 0.951 +- 0.030 (stat) +- 0.015 (syst).

0 data tables match query

Measurement of the inclusive D*+- production in gamma gamma collisions at LEP.

The ALEPH collaboration Heister, A. ; Schael, S. ; Barate, R. ; et al.
Eur.Phys.J.C 28 (2003) 437-449, 2003.
Inspire Record 612223 DOI 10.17182/hepdata.48891

The inclusive production of D$^{*\pm}$ mesons in two-photon collisions is measured with the ALEPH detector at $\epem$ centre-of-mass energies from 183$\unit{GeV}$ to 209$\unit{GeV}$. A total of $360 \pm 27$ D$^{*\pm}$ meson events were observed from an integrated luminosity of 699\unit{pb^{-1}}$. Contributions from direct and single-resolved rocesses are separated using the ratio of the transverse momentum $p_{\rm t}^{\rm D^{*\pm}}$ of the D$^{*\pm}$ to the visible invariant mass $W_{\mathrm{vis}}$ of the event. Differential cross sections of D$^{*\pm}$ production as functions of $p_{\rm t}^{\rm D^{*\pm}}$ and the pseudorapidity $|\eta^{\rm D^{*\pm}}| $ are measured in the range $ 2\unit{GeV}/c < p_{\rm t}^{\rm D^{*\pm}} < 12\unit{GeV}/c $ and $ |\eta^{\rm D^{*\pm}}| < 1.5 $. They are compared to next-to-leading order (NLO)perturbative QCD calculations. The extrapolation of the integrated visible D$^{*\pm}$ cross section to the total charm cross section, based on the Pythia Monte Carlo program, yields $ \sigma (\epem \to \epem \ccbar)_ {=197\unit{GeV}} = 731 \pm 74_{\mathrm{stat}} \pm 47_{\mathrm{syst}} \pm 157_{\mathrm{extr}} \unit{pb} $.

0 data tables match query

Measurement of the D*+- cross-section in two photon collisions at LEP

The ALEPH collaboration Buskulic, D. ; Casper, D. ; De Bonis, I. ; et al.
Phys.Lett.B 355 (1995) 595-605, 1995.
Inspire Record 394752 DOI 10.17182/hepdata.47950

The inclusive production of D ∗± mesons in photon-photon collisions has been measured by the Aleph experiment at LEP with a beam energy of 45 GeV. The D ∗+ are detected in their decay to D 0 π + with the D 0 observed in three separate decay modes: (1) K − π + , (2) K − π + π 0 and (3) K − π + π − π + , and analagously for the D ∗− modes. A total of 33 events was observed from an integrated luminosity of 73 pb −1 which corresponds to a cross section for Σ( e + e − → e + e − D ∗± X ) of 155 ± 33 ± 21 pb. This result is compatible with both the direct production γγ → c c in the Born approximation and with a more complete calculation which includes both radiative QCD corrections and contributions in which one of the photons is first resolved into its quark and gluon constituents. The shapes of distributions for events containing a D ∗+ are found to be better described by the latter.

0 data tables match query

Measurement of the W mass in e+ e- collisions at production threshold

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 401 (1997) 347-362, 1997.
Inspire Record 441188 DOI 10.17182/hepdata.47488

In June 1996, the LEP centre-of-mass energy was raised to 161 GeV. Pair production of W bosons in e + e − collisions was observed for the first time by the LEP experiments. An integrated luminosity of 11 pb −1 was recorded in the ALEPH detector, in which WW candidate events were observed. In 6 events both Ws decay leptonically. In 16 events, one W decays leptonically, the other into hadrons. In the channel where both Ws decay into hadrons, a signal was separated from the large background by means of several multi-variate analyses. The W pair cross-section is measured to be σ WW = 4.23 ± 0.73 (stat.) ± 0.19 (syst.) pb. From this cross-section, the W mass is derived within the framework of the Standard Model: m W = 80.14 ± 0.34 (stat.) ± 0.09 (syst.) ± 0.03 (LEP energy) GeV/ c 2

0 data tables match query

Measurement of W pair production in e+ e- collisions at 183-GeV.

The ALEPH collaboration Barate, R. ; Decamp, D. ; Ghez, Philippe ; et al.
Phys.Lett.B 453 (1999) 107-120, 1999.
Inspire Record 497105 DOI 10.17182/hepdata.49130

The production of W+W- pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 182.7 GeV, corresponding to an integrated luminosity of 57 pb-1. Cross sections are given for different topologies of W decays into leptons or hadrons. Under Standard Model assumptions for the W-pair production and decay, the W-pair cross section is measured to be 15.57+-0.62(stat.)+-0.29(syst.) pb. Using also the W-pair data samples collected by ALEPH at lower centre-of-mass energies, the decay branching ratio of the W boson into hadrons is measured to be B(W->hadrons)= 68.93+-1.21(stat.)+-0.51(syst.)%, allowing a determination of the CKM matrix element |Vcs|= 1.043 +- 0.058(stat.) +- 0.026(syst.). The agreement of the cross sections with the Standard Model prediction allows a limit to be set on the W decay rate to undetectable final states.

0 data tables match query

Exclusive production of pion and kaon meson pairs in two photon collisions at LEP.

The ALEPH collaboration Heister, A. ; Schael, S. ; Barate, R. ; et al.
Phys.Lett.B 569 (2003) 140-150, 2003.
Inspire Record 626022 DOI 10.17182/hepdata.49730

Exclusive production of π and K meson pairs in two photon collisions is measured with ALEPH data collected between 1992 and 2000. Cross-sections are presented as a function of cos θ ∗ and invariant mass, for | cos θ ∗ |<0.6 and invariant masses between 2.0 and 6.0 GeV/ c 2 (2.25 and 4.0 GeV/ c 2 ) for pions (kaons). The shape of the distributions are found to be well described by QCD predictions but the data have a significantly higher normalization.

0 data tables match query

Deuteron production in alpha nucleus collisions from 200-MeV to 800-MeV per nucleon

Montarou, G. ; Alard, J.P. ; Augerat, J. ; et al.
Phys.Rev.C 44 (1991) 365-383, 1991.
Inspire Record 28947 DOI 10.17182/hepdata.26158

Deuteron spectra at laboratory angles from 30° to 90° were measured in α+(Pb, Cu, and C) collisions at 800, 600, and 200 MeV/nucleon, and α+(Pb and C) collisions at 400 MeV/nucleon. The coalescence relation between protons and deuterons was examined for the inclusive part of the spectra. The size of the interacting region was evaluated from the observed coalescence coefficients. The rms radius is typically 4–5 fm, depending of the target mass. The proton and deuteron energy spectra corresponding to central collisions were fitted assuming emission from a single source moving with a velocity intermediate between that of the projectile and the target. The extracted ‘‘temperatures’’ are independent of the nature of the emitted particle, indicating that the fragments have a common source. The best fits were achieved for 200- and 400-MeV/nucleon reactions. Spectra of deuteron-like pairs, including real deuterons and neutron-proton pairs that may be contained in a larger nuclear cluster, are compared to the prediction of an intranuclear cascade model incorporating a clustering algorithm based on a classical coalescence prescription. Best agreements between experimental and predicted deuteron-like spectra occur for 800- and 600-MeV/nucleon collisions.

0 data tables match query

Production of Pions and Light Fragments at Large Angles in High-Energy Nuclear Collisions

Nagamiya, S. ; Lemaire, M.C. ; Moller, E. ; et al.
Phys.Rev.C 24 (1981) 971-1009, 1981.
Inspire Record 169971 DOI 10.17182/hepdata.26341

Inclusive cross sections for production of π+, π−, p, d, H3, He3, and He4 have been measured at laboratory angles from 10° to 145° in nuclear collisions of Ne + Naf, Ne + Cu, and Ne + Pb at 400 MeV/nucleon, C + C, C + Pb, Ne + NaF, Ne + Cu, Ne + Pb, Ar + KCl, and Ar + Pb at 800 MeV/nucleon, and Ne + NaF and Ne + Pb at 2.1 GeV/nucleon. The production of light fragments in proton induced collisions at beam energies of 800 MeV and 2.1 GeV has also been measured in order to allow us to compare these processes. For equal-mass nuclear collisions the total integrated yields of nuclear charges are well explained by a simple participant-spectator model. For 800 MeV/nucleon beams the energy spectra of protons at c.m. 90° are characterized by a "shoulder-arm" type of spectrum shape with an exponential falloff at high energies, whereas those of pions are of a simple exponential type. The inverse of the exponential slope, E0, for protons is systematically larger than that for pions. This value of E0 is larger for heavier-mass projectiles and targets. It also increases monotonically with the beam energy. The angular anisotropy of protons is larger than that of pions. The yield ratio of π− to total nuclear charge goes up with the beam energy, whereas the yields of composite fragments decrease. The ratio of low-energy π− to π+, as well as that of H3 to He3, is larger than the neutron to proton ratio of the system. The spectrum shape of the composite fragments with mass number A is explained very well by the Ath power of the observed proton spectra. The sizes of the interaction region are evaluated from the observed coalescence coefficients. The radius obtained is typically 3-4 fm. The yield ratio of composite fragments to protons strongly depends on the projectile and target masses and the beam energy, but not on the emission angle of the fragments. These results are compared with currently available theoretical models. NUCLEAR REACTIONS Ne + NaF, Ne + Cu, Ne + Pb, EA=400 MeV/nucleon; C + C, C + Pb, Ne + NaF, Ne + Cu, Ne + Pb, Ar + KCl, Ar + Pb, EA=800 MeV/nucleon; Ne + NaF, Ne + Pb, EA=2100 MeV/nucleon; p + C, p+ NaF, p + KCl, p + Cu, p + Pb, E=800 MeV; p + C, p + NaF, p + KCl, p + Cu, p + Pb, E=2100 MeV; measured σ(p,θ) for π+, π−, p, d, H3, He3, and He4.

0 data tables match query

Measurement of the W pair cross section in e+ e- collisions at 172-GeV.

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 415 (1997) 435-444, 1997.
Inspire Record 446940 DOI 10.17182/hepdata.47408

The e + e − → W + W − cross section is measured in a data sample collected by ALEPH at a mean centre-of-mass energy of 172.09 GeV, corresponding to an integrated luminosity of 10.65 pb −1 . Cross sections are given for the three topologies, fully leptonic, semi-leptonic and hadronic of a W-pair decay. Under the assumption that no other decay modes are present, the W-pair cross section is measured to be 11.7±1.2 (stat.) ±0.3 (syst.) pb . The existence of the triple gauge boson vertex of the Standard Model is clearly preferred by the data. The decay branching ratio of the W boson into hadrons is measured to be B(W→hadrons) =67.7±3.1 (stat.) ±0.7 (syst.) % , allowing a determination of the CKM matrix element | V cs |=0.98±0.14(stat.)±0.03(syst.).

0 data tables match query

Study of fermion pair production in e+ e- collisions at 130-GeV to 183-GeV

The ALEPH collaboration Barate, R. ; Decamp, D. ; Ghez, Philippe ; et al.
Eur.Phys.J.C 12 (2000) 183-207, 2000.
Inspire Record 498072 DOI 10.17182/hepdata.49128

The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e+e- collisions at centre-of-mass energies of 130-183 GeV are presented. Results for ee, mumu, tautau, qq, bb and cc production show no significant deviation from the Standard Model predictions. This enable constraints to be set upon physics beyond the Standard Model such as four-fermion contact interactions, leptoquarks, Z' bosons and R-parity violating squarks and sneutrinos. Limits on the energy scale Lambda of eeff contact interactions are typically in the range from 2-10 TeV. Limits on R-parity violating sneutrinos reach masses of a few hundred GeV for large values of their Yukawa couplings.

0 data tables match query