HEPData Search

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Observation of the p wave singlet state of charmonium

Armstrong, T.A. ; Bettoni, D. ; Bharadwaj, V. ; et al.

Phys.Rev.Lett. 69 (1992) 2337-2340, 1992.

Inspire Record 338054 DOI 10.17182/hepdata.42562

We have performed a search for the 1P1 state of charmonium resonantly formed in p¯p annihilations, close to the center of gravity of the 3PJ states. We report results from the study of the J/ψ+π0 and J/ψ+2π final states. We have observed a statistically significant enhancement in the p¯+p→J/ψ+π0 cross section at √s ≃3526.2 MeV. This enhancement has the characteristics of a narrow resonance of mass, total width, and production cross section consistent with what is expected for the 1P1 state. In our search we have found no candidates for the reactions p¯+p→J/ψ+π0+π0 and p¯+p→J/ψ+π++π−.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Near threshold photoproduction of eta mesons from He-4.

Hejny, V. ; Achenbach, P. ; Ahrens, J. ; et al.

Eur.Phys.J.A 6 (1999) 83-89, 1999.

Inspire Record 509583 DOI 10.17182/hepdata.43494

None

1 data table

Table 1

SIG(Q=N) and SIG(Q=P) ratio is extracted from the data of scattering on HE4.

Near-threshold eta production in the p d --> p d eta reaction.

Hibou, F. ; Wilkin, Colin ; Bergdolt, A.M. ; et al.

Eur.Phys.J.A 7 (2000) 537-541, 2000.

Inspire Record 523315 DOI 10.17182/hepdata.43410

The total cross section of the p d -> p d eta reaction has been measured at two energies near threshold by detecting the final proton and deuteron in a magneti spectrometer. The values are somewhat larger than expected on the basis of two simple theoretical estimates.

1 data table

Table 1

The first quoted error includes statistical and normalization uncertainties, the scond is that induced by the uncertainty in the excess energy.

Near threshold eta meson production in the d d --> He-4 eta reaction.

Wrońska, A. ; Hejny, V. ; Wilkin, C. ; et al.

Eur.Phys.J.A 26 (2005) 421-428, 2005.

Inspire Record 695766 DOI 10.17182/hepdata.43489

The d+d->alpha+eta reaction has been investigated near threshold using the ANKE facility at COSY-Juelich. Both total and differential cross sections have been measured at two excess energies, Q=2.6 MeV and 7.7 MeV, with a subthreshold measurement being undertaken at Q=-2.6 MeV to study the physical background. While consistent with isotropy at the lower energy, the angular distribution reveals a pronounced anisotropy at the higher one, indicating the presence of higher partial waves. Options for the decomposition into partial amplitudes and their consequences for determination of the s-wave eta-alpha scattering length are discussed.

3 data tables

Table 1

Measured cross sections. Systematic (DSYS) error does not include the luminosity uncertainty.

Table 2

Experimental angular distribution at excess energy 2.6 MeV.

Table 3

Experimental angular distribution at excess energy 7.7 MeV.

Kaon production in nucleus nucleus collisions at 92-MeV per nucleon.

Legrain, R. ; Lecolley, J.F. ; Lecolley, F.R. ; et al.

Phys.Rev.C 59 (1999) 1464-1471, 1999.

Inspire Record 450061 DOI 10.17182/hepdata.47065

K+ production far below the free nucleon-nucleon threshold has been investigated in collisions of 36Ar on 12C, natTi, and 181Ta targets at an incident energy of 92 MeV per nucleon. The cross sections for K+ production have been inferred from the observed muon decays of positive kaons. The results are discussed in the framework of a participant-spectator model and are compared to proton induced K+ production and to subthreshold pion production experiments.

1 data table

Table 1

Three different production modes are assumed: (C=ISOTROPIC) isotropic emmision inthe lab frame with a kinetic energy EKIN(K) = 35 MeV, (C=SPECTRUM) isotropic emmision inthe lab frame with a kinetic energy spectrum from S. Gosh, PR C45,R518, (C=FIREBALL) isotropic emmision in the fireball frame with a kinetic ener gy EKIN(K) = 35 MeV.

Total cross section measurement of the gamma n --> p pi- pi0 reaction.

Zabrodin, A. ; Audit, G. ; Beck, R. ; et al.

Phys.Rev.C 55 (1997) R1617-R1620, 1997.

Inspire Record 439886 DOI 10.17182/hepdata.47015

The total cross section for the γn→pπ−π0 reaction has been measured over the photon energy range 450–800 MeV at the 855 MeV MAMI Microtron in Mainz with the large acceptance detector DAPHNE and using a deuterium target. As expected, this reaction has a very similar cross section to the γp→nπ+π0 channel and its amplitude is strongly underestimated by the existing double pion photoproduction models.

1 data table

Table 1

No description provided.

The reaction ${n} {p} \to {p} {p} \pi^{-}$ from threshold up to 570 MeV

Daum, M. ; Finger, M. ; Finger, Michael, Jr. ; et al.

Eur.Phys.J.C 23 (2002) 43-59, 2002.

Inspire Record 561221 DOI 10.17182/hepdata.43221

The reaction ${n} {p} \to {p} {p} \pi^{-}$ has been studied in a kinematically complete measurement with a large acceptance time-of-flight spectrometer for incident neutron energies between threshold and 570 MeV. The proton-proton invariant mass distributions show a strong enhancement due to the pp($^{1}{S}_{0}$) final state interaction. A large anisotropy was found in the pion angular distributions in contrast to the reaction ${p}{p} \to {p}{p} \pi^{0}$. At small energies, a large forward/backward asymmetry has been observed. From the measured integrated cross section $\sigma({n}{p} \to {\rm p}{p} \pi^{-})$, the isoscalar cross section $\sigma_{01}$ has been extracted. Its energy dependence indicates that mainly partial waves with Sp final states contribute. Note: Due to a coding error, the differential cross sections ${d \sigma}/{d M_{pp}}$ as shown in Fig. 9 are too small by a factor of two, and inn Table 3 the differential cross sections ${d \sigma}/{d \Omega_{\pi}^{*}}$ are too large by a factor of $10/2\pi$. The integrated cross sections and all conclusions remain unchanged. A corresponding erratum has been submitted and accepted by European Physics Journal.

4 data tables

Table 1

Differential cross sections DSIG/DOMEGA for excusive PI- production in N P interactions at incident kinetic energies 315, 345 and 375 Mev after background subtraction and efficiency correction.

Table 2

Differential cross sections DSIG/DOMEGA for exclusive PI- production in N Pinteractions at incident kinetic energies 405, 435 and 465 Mev after background subtraction and efficiency correction.

Table 3

Differential cross sections DSIG/DOMEGA for exclusive PI- production in N Pinteractions at incident kinetic energies 495, 525 and 550 Mev after background subtraction and efficiency correction.

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A measurement of the photonuclear interactions of 180-GeV muons in iron

Alexa, C. ; Anderson, K. ; Antonaki, A. ; et al.

Eur.Phys.J.C 28 (2003) 297-304, 2003.

Inspire Record 621812 DOI 10.17182/hepdata.43173

The energy spectrum and the cross section of photonuclear interactions of 180 GeV muons in iron were measured at the CERN SPS using prototype modules of the ATLAS hadron calorimeter. The differential

2 data tables

Table 1

Measured differential cross section for fractional photonuclear muon energy loss.

Table 2

Total photonuclear cross section which gives best agreement of energy loss with theory. See text of paper for details.

Electroproduction of $\rho^0$ Mesons

Cohen, I. ; Erickson, R. ; Messing, F. ; et al.

Phys.Rev.D 25 (1982) 634, 1982.

Inspire Record 152921 DOI 10.17182/hepdata.47139

Cross sections for ρ0 electroproduction measured in a streamer-chamber experiment are separated into elastic (ep→epρ0) and inelastic production channels. For the elastic channel, the total cross section and t dependence are presented. For the inelastic channel (1σ)dσdz, (1σ)dσdpT2, and a density matrix element are shown and compared to quark-parton-model predictions. The ratio of ρ0 to direct π0 production is found to be 2.0±0.5±0.3, where the first error is statistical, and the second error is systematic.

8 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.