Date

High-statistics measurement of neutral pion-pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Adachi, I. ; et al.
Phys.Rev.D 78 (2008) 052004, 2008.
Inspire Record 786406 DOI 10.17182/hepdata.50151

We report a high-statistics measurement of differential cross sections for the process gamma gamma -> pi^0 pi^0 in the kinematic range 0.6 GeV <= W <= 4.0 GeV and |cos theta*| <= 0.8, where W and theta* are the energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. Differential cross sections are fitted to obtain information on S, D_0, D_2, G_0 and G_2 waves. The G waves are important above W ~= 1.6 GeV. For W <= 1.6 GeV the D_2 wave is dominated by the f_2(1270) resonance while the S wave requires at least one additional resonance besides the f_0(980), which may be the f_0(1370) or f_0(1500). The differential cross sections are fitted with a simple parameterization to determine the parameters (the mass, total width and Gamma_{gamma gamma}B(f_0 -> pi^0 pi^0)) of this scalar meson as well as the f_0(980). The helicity 0 fraction of the f_2(1270) meson, taking into account interference for the first time, is also obtained.

29 data tables

Differential cross section for W = 0.61, 0.63 and 0.65 GeV.

Differential cross section for W = 0.67, 0.69 and 0.71 GeV.

Differential cross section for W = 0.73, 0.75 and 0.77 GeV.

More…

A study of gamma gamma -> Ks Ks production at energies of 2.4-4.0GeV at Belle

The Belle collaboration Chen, W.T. ; Abe, Kazuo ; Abe, K. ; et al.
Phys.Lett.B 651 (2007) 15-21, 2007.
Inspire Record 726900 DOI 10.17182/hepdata.38419

$K^0_SK^0_S$ production in two-photon collisions has been studied using a 397.6 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+e^-$ collider. For the first time the cross sections are measured in the two-photon center-of-mass energy range between 2.4 GeV and 4.0 GeV and angular range $|\cos\theta^*|<0.6$. Combining the results with measurements of $\gamma\gamma\to K^+K^-$ from Belle, we observe that the cross section ratio $\sigma(K^0_SK^0_S)/\sigma(K^+K^-)$ decreases from ~0.13 to ~0.01 with increasing energy. Signals for the $\chi_{c0}$ and $\chi_{c2}$ charmonium states are also observed.

7 data tables

Total cross section for the process GAMMA GAMMA --> K0S K0S.

Angular distribution of the cross section in the W range 2.4 to 2.5 GeV.

Angular distribution of the cross section in the W range 2.5 to 2.6 GeV.

More…

Proton anti-proton pair production in two photon collisions at LEP

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 571 (2003) 11-20, 2003.
Inspire Record 620433 DOI 10.17182/hepdata.48883

The reaction e^+e^- -> e^+e^- proton antiproton is studied with the L3 detector at LEP. The analysis is based on data collected at e^+e^- center-of-mass energies from 183 GeV to 209 GeV, corresponding to an integrated luminosity of 667 pb^-1. The gamma gamma -> proton antiproton differential cross section is measured in the range of the two-photon center-of-mass energy from 2.1 GeV to 4.5 GeV. The results are compared to the predictions of the three-quark and quark-diquark models.

4 data tables

Total cross section for P PBAR production at a mean centre-of-mass energy of 197 GeV.

The cross section as a function of W for ABS(COS(THETA)) < 0.6.

The differential cross section as a function of COS(THETA*) for three W ranges.

More…

Measurement of the cross-section for the process gamma gamma --> p anti-p at s(ee)**(1/2) = 183-GeV - 189-GeV at LEP.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 28 (2003) 45-54, 2003.
Inspire Record 595836 DOI 10.17182/hepdata.48881

The exclusive production of proton-antiproton pairs in the collisions of two quasi-real photons had been studied using data taken at sqrt(s)_ee=183 GeV and 189 GeV with the OPAL detector at LEP. Results are presented for Ppbar invariant masses, W, in the range 2.15 W< <3.95 GeV. The cross-section measurements are compared with previous data and with recent analytic calculations based on the quark-diquark model.

3 data tables

Cross section as a function of the invariant mass of the pbar-p pair.

Cross section for two photon production of the pbar-p pair.

Angular distributions in 3 W ranges.


A MEASUREMENT OF THE TOTAL HADRONIC CROSS-SECTION IN TAGGED gamma gamma REACTIONS

The TPC/Two Gamma collaboration Aihara, H. ; Alston-Garnjost, M. ; Avery, R.E. ; et al.
Phys.Rev.D 41 (1990) 2667, 1990.
Inspire Record 281351 DOI 10.17182/hepdata.22991

We present a measurement of the total cross section for γγ→hadrons, with one photon quasireal and the other a spacelike photon of mass squared −Q2. Results are presented as a function of Q2 and the γγ center-of-mass energy W, with the Q2 range extending from 0.2 to 60 GeV2, and W in the range from 2 to 10 GeV. The data were taken with the TPC/Two-Gamma facility at the SLAC e+e− storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle falloff with increasing W. Its Q2 dependence is shown to be well described by an incoherent sum of vector-meson and pointlike scattering over most of the observed W range. Agreement at high Q2 is improved if a minimum-pT cutoff (motivated by QCD) is imposed on the pointlike contribution.

4 data tables

Errors are statistical only.

Errors are statistical only.

Errors are statistical only.

More…

Vector Meson Production in the Final State $K^+ K^- \pi^+ \pi^-$ Photon-photon Collisions

The TASSO collaboration Althoff, M. ; Braunschweig, W. ; Gerhards, R. ; et al.
Z.Phys.C 32 (1986) 11, 1986.
Inspire Record 228250 DOI 10.17182/hepdata.15846

Vector meson production is studied in the reaction γγ→K+K−π+π−. A clear Φ(1020) signal is seen in theK+K− mass distribution and aK*0 (890) signal is visible in theK±π∓ one. Both do not seem to be strongly correlated with quasi two body final states. Cross sections for the processes γγ→K+K−π+π−, γγ→Φπ+π−, γγ→K+0K±π∓ and upper limits for the production of Φp, ΦΦ andK*0\(\overline {K^{ * 0} } \) are given as function of the invariant γγ mass.

5 data tables

No description provided.

First data point is sum of (K* K PI) and (K* AK*).

Non resonant phase space.

More…

Charged Meson Pair Production in $\gamma \gamma$ Interactions

Boyer, J. ; Burke, D.L. ; Butler, F. ; et al.
Phys.Rev.Lett. 56 (1986) 207, 1986.
Inspire Record 220003 DOI 10.17182/hepdata.20236

The cross section for the production of π+π− or K+K− pairs in γγ interactions is measured for mππ between 1.7 and 3.5 GeV/c2 and for two intervals of γγ center-of-mass scattering angle. Results are compared with predictions of a QCD model.

2 data tables

Data read off graph.

Data read off graph.


Study of the Reaction $\gamma \gamma \to 2 \pi^+ 2 \pi^- \pi^0$ and Upper Limits on the Production of $\gamma \gamma \to \omega \omega$ and $\gamma \gamma \to \rho^0 \omega$

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Lackas, W. ; et al.
Z.Phys.C 29 (1985) 183, 1985.
Inspire Record 220911 DOI 10.17182/hepdata.15911

A search for the reactionsγγ→ωω andγγ→ρ0ω has been carried out at an averagee+e− CM energy of 34.6 GeV with an integrated luminosity of 45 pb−1. Upper limits are set for these two channels over the γγ CM Energy range of 1.6 to 2.5 GeV. The cross section is determined for the exclusive channelγγ→π+2π−π0.

3 data tables

Data read from graph.

Data read from graph.

Data read from graph.


EXCLUSIVE PRODUCTION OF K+ K- pi+ pi- IN PHOTON-PHOTON COLLISIONS

The TPC/Two Gamma collaboration Aihara, H. ; Alston-Garnjost, M. ; Armitage, J.C. ; et al.
Phys.Rev.Lett. 54 (1985) 2564, 1985.
Inspire Record 213402 DOI 10.17182/hepdata.20345

We report a measurement of the reaction γγ→K+K−π+π− in both tagged and untagged events at PEP. The cross section rises with invariant γγ mass to about 15 nb at 2 GeV and falls slowly at higher masses. We find clear evidence for the processes γγ→φπ+π− and γγ→K*0(892)Kπ. Upper limits (95% C.L.) of 1.5 and 5.7 nb in the mass range from 1.7 to 3.7 GeV are obtained for φρ0 and K*0K¯*0 production, respectively.

8 data tables

No description provided.

No description provided.

Untagged sample, (non-resonant).

More…

MEASUREMENT OF THE REACTION gamma p ---> p anti-p p AT PHOTON ENERGIES 4.7-GeV <= E (gamma) <= 6.6-GeV

Bodenkamp, J. ; Fries, D.C. ; Markou, A. ; et al.
Nucl.Phys.B 255 (1985) 717-746, 1985.
Inspire Record 15090 DOI 10.17182/hepdata.33786

An experimental investigation of the reaction γ p → p p p at photon energies 4.7 ⩽ E γ ⩽ 6.6 GeV is described. The main results are the measurement of the cross section as a function of energy, a discussion of the main dynamical features of the reaction and the observation of a narrow p p mass state at 2.024 ± 0.005 GeV with a width of 29 ± 13 MeV.

3 data tables

OBSERVATION OF THIS CHANNEL AS A CONSISTENCY CHECK ON THE NORMALIZATION.

No description provided.

MEASUREMENTS OF CROSS SECTIONS OF MASS SIGNALS AT 1.94 AND 2.024 GEV, EVALUATE BY FITTING TWO BREIT WIGNERS AND CONSTANT BACKGROUND TO (AP P) MASS SPECTRUM. ERRORS ARE STATISTICAL ONLY.