Schwanda, C.
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MEASUREMENT OF THE INCLUSIVE BRANCHING FRACTION tau- ---> tau-neutrino pi- pi0 NEUTRAL MESON(S)

The TPC/Two Gamma collaboration Aihara, H. ; Alston-Garnjost, M. ; Avery, R.E. ; et al.
Phys.Rev.Lett. 57 (1986) 1836, 1986.
Inspire Record 233422 DOI 10.17182/hepdata.38106

We measure an inclusive branching fraction of (13.9 ± 2.0−2.2+1.9)% for the decay τ−→ντπ−π0+nh0(n>~1), where h0 is a π0 or an η. The data sample, obtained with the time-projection-chamber detector facility at the SLAC e+e− storage ring PEP, corresponds to an integrated luminosity of 72 pb−1 at 29 GeV center-of-mass energy. The measured branching fraction is somewhat greater than the theoretical prediction and, with errors taken into account, could resolve the present difference between the inclusive and the sum of the exclusive τ± branching fractions into one charged prong.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


2.22-{GeV} $\eta \eta^\prime$ Structure Observed in 38-{GeV}/$c$ and 100-{GeV}/$c \pi^- p$ Collisions

The Serpukhov-Brussels-Los Alamos-Annecy(LAPP) collaboration Alde, D. ; Binon, F. ; Bricman, C. ; et al.
Phys.Lett.B 177 (1986) 120, 1986.
Inspire Record 230300 DOI 10.17182/hepdata.40940

A structure has been observed at 2220 MeV in the mass spectrum of ηη ′ systems produced by 38GeV/ c and 100 GeV/ c ′ negative pions on protons. The angular distribution of the decay products shows that this structure is presumably a spin J ⩾ 2 meson.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


A Precise Measurement of Neutral Pion Photoproduction on the Proton Near Threshold

Mazzucato, E. ; Argan, P. ; Audit, G. ; et al.
Phys.Rev.Lett. 57 (1986) 3144, 1986.
Inspire Record 230501 DOI 10.17182/hepdata.20203

An absolute measurement of π0 photoproduction on the proton has been carried out in the threshold region (from 144.7 to 173 MeV) by use of tagged annihilation photons. The measured cross sections, differential in the recoiling-proton energy, are used to perform a multipole analysis which gives a value & &, in disagreement with low-energy-theorem predictions. Total cross sections and coefficients of the π0 angular distribution are presented.

1 data table
Table 1

No description provided.


A Measurement of the Strong Coupling Constant $\alpha^- s$ to Complete Second Order

The Mark-J collaboration Adeva, B. ; Anderhub, H. ; Ansari, S. ; et al.
Phys.Lett.B 180 (1986) 181-184, 1986.
Inspire Record 231302 DOI 10.17182/hepdata.6535

The strong interaction coupling constant α s has been measured with a new method, the planar triple energy correlation in the reaction e + e - → hadrons at center-of-mass energies ranging from 14 GeV to 46.78 GeV. A complete second-order perturbative QCD calculation was used. Λ MS = 110 ± 30 −55 +70 MeV is found.

3 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.


A Measurement of the Sigma- Magnetic Moment Using the Sigma- ---> n e- anti-neutrino and Sigma- ---> n pi- Decay Modes

Zapalac, G. ; Hsueh, S.Y. ; Muller, D. ; et al.
Phys.Rev.Lett. 57 (1986) 1526, 1986.
Inspire Record 231107 DOI 10.17182/hepdata.42694

We have used the spin-precession technique to measure the Σ− magnetic moment (μΣ). A Σ− beam with a polarization of 22% was produced by a 400-GeV proton beam striking a Cu target at nominal production angles of ±3 mrad. We simultaneously recorded 21 000 Σ−→ne−ν¯ decays and 650 000 Σ−→nπ− decays at Σ− beam momenta of 253 and 308 GeV/c. We find μΣ=−1.166±0.014±0.010 nuclear magnetons, where the quoted errors are statistical and systematic, respectively.

1 data table
Table 1

No description provided.


Experimental Study of the Reactions $e^+ e^- \to e^+ e^-$ and $e^+ e^- \to \gamma \gamma$ at 29-{GeV}

Derrick, M. ; Gan, K.K. ; Kooijman, P. ; et al.
Phys.Rev.D 34 (1986) 3286, 1986.
Inspire Record 18585 DOI 10.17182/hepdata.23442

This paper reports measurements of the differential cross sections for the reactions e+e−→e+e− (Bhabha scattering) and e+e−→γγ (γ-pair production). The reactions are studied at a center-of-mass energy of 29 GeV and in the polar-angular region ‖costheta‖<0.55. A direct cross-section comparison between these two reactions provides a sensitive test of the predictions of quantum electrodynamics (QED) to order α3. When the ratio of γ-pair to Bhabha experimental cross sections, integrated over ‖costheta‖<0.55, is divided by the same ratio predicted from α3 QED theory, the result is 1.007±0.009±0.008. The 95%-confidence limits on the QED-cutoff parameters are Λ+>154 GeV and Λ−>220 GeV for Bhabha scattering, and Λ+>59 GeV and Λ−>59 GeV for γ-pair production.

1 data table
Table 1

No description provided.


Inclusive $\eta$ Production at Low Transverse Momentum in 63-{GeV} $p p$ Collisions at the {CERN} Intersecting Storage Rings

The Axial Field Spectrometer collaboration Akesson, T. ; Albrow, M.G. ; Almehed, S. ; et al.
Phys.Lett.B 178 (1986) 447, 1986.
Inspire Record 230636 DOI 10.17182/hepdata.30230

The inclusive production of η-mesons in pp collisions at √ s =63GeV and ϑ CM =90° has been measured for p T <1.5GeV/c. The η/π ratio decreases from its previously measured asymptotic value of η/π ∼ 0.5 at high transverse momentum, to η/π ≈0.3 at P T = 750MeV/c and η/π ≈ 0.01 at P T =300MeV/c, in a way that consistent with phase-space considerations, e.g. m T scaling. The η/π ratio, integrated from 0.2–1.5 GeV/ c , is found to be η/π=0.07±0.055.

1 data table
Table 1

No description provided.


A Measurement of the Kaon Charge Radius

Amendolia, S.R. ; Batignani, G. ; Beck, G.A. ; et al.
Phys.Lett.B 178 (1986) 435-440, 1986.
Inspire Record 231129 DOI 10.17182/hepdata.30242

The negative kaon electromagnetic form factor has been measured in the space-like q 2 range 0.015–0.10 (GeV/ c ) 2 by the direct scattering of 250 GeV kaons from electrons at the CERN SPS. It is found that the kaon mean square charge radius 〈 r 2 K 〉 = 0.34 ± 0.05 fm 2 . From data collected simultaneously for πe scattering, the difference between the charged pion and kaon mean square radii (which is less sensitive to systematic errors) is found to be 〈 r 2 π 〉 − 〈 r 2 K = 0.1 0 ± 0.045 fm 2 .

1 data table
Table 1

Ratio is assumed free of systematic error.


Angular Distributions for High Mass Jet Pairs and a Limit on the Energy Scale of Compositeness for Quarks from the CERN p anti-p Collider

The UA1 collaboration Arnison, G. ; Albajar, C. ; Albrow, M.G. ; et al.
Phys.Lett.B 177 (1986) 244-250, 1986.
Inspire Record 230633 DOI 10.17182/hepdata.30248

Angular distributions of high-mass jet pairs (180< m 2 J <350 GeV) have been measured in the UA1 experiment at the CERN pp̄ Collider ( s =630 GeV ) . We show that angular distributions are independent of the subprocess centre-of-mass (CM) energy over this range, and use the data to put constraints on the definition of the Q 2 scale. The distribution for the very high mass jet pairs (240< m 2 J <300 GeV) has also been used to obtain a lower limit on the energy scale Λ c of compositeness of quarks. We find Λ c >415 GeV at 95% confidence level.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


COMPARISON OF THE PARTICLE FLOW IN q anti-q g AND q anti-q gamma EVENTS IN e+ e- ANNIHILATION

The TPC/Two Gamma collaboration Aihara, H. ; Alston-Garnjost, M. ; Avery, R.E. ; et al.
Phys.Rev.Lett. 57 (1986) 945, 1986.
Inspire Record 230224 DOI 10.17182/hepdata.38183

We compare the particle flow in the event plane of three-jet qq¯g (quark-antiquark-gluon) events with the particle flow in radiative annihilation events qq¯γ (quark-antiquark-photon) for similar kinematic configurations. In the angular region between quark and antiquark jet, we find a significant decrease in particle density for qq¯g as compared to qq¯γ. This effect is predicted in QCD as a result of destructive interference between soft-gluon radiation from quark, antiquark, and hard gluon.

2 data tables
Table 1

No description provided.

Table 2

No description provided.