Measurement of the photon structure function at high Q**2 at LEP

The L3 collaboration Acciarri, M. ; Achard, P. ; Adriani, O. ; et al.
Phys.Lett.B 483 (2000) 373-386, 2000.
Inspire Record 525764 DOI 10.17182/hepdata.49964

The structure functions of real and virtual photons are derived from cross section measurements of the reaction e^+e^ -> e^+e^- + hadrons at LEP. The reaction is studied at \sqrt{s} ~ 91 GeV with the L3 detector. One of the final state electrons is detected at a large angle relative to the beam direction, leading to Q^2 values between 40 GeV^2 and 500 GeV^2. The other final state electron is either undetected or it is detected at a four-momentum transfer squared P^2 between 1 GeV^2 and 8 GeV^2. These measurements are compared with predictions of the Quark Parton Model and other QCD based models.

4 data tables

Measured values of F2 for the single-tag data as a function of X for the full Q**2 range.

Measured values of F2 for the single-tag data as a function of Q**2 for different X ranges.

The effective F2 measured in double-tag events as a function of X.

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The Q**2 evolution of the hadronic photon structure function F2(gamma) at LEP.

The L3 collaboration Acciarri, M. ; Achard, P. ; Adriani, O. ; et al.
Phys.Lett.B 447 (1999) 147-156, 1999.
Inspire Record 479052 DOI 10.17182/hepdata.49323

New measurements at a centre-of-mass energy s ≃183 GeV of the hadronic photon structure function F γ 2 ( x ) in the Q 2 interval, 9 GeV 2 ≤ Q 2 ≤30 GeV 2 , are presented. The data, collected in 1997 with the L3 detector, correspond to an integrated luminosity of 51.9 pb −1 . Combining with the data taken at a centre-of-mass energy of 91 GeV, the evolution of F γ 2 with Q 2 is measured in the Q 2 range from 1.2 GeV 2 to 30 GeV 2 . F γ 2 shows a linear growth with ln Q 2 ; the value of the slope α −1 d F γ 2 ( Q 2 )/dln Q 2 is measured in two x bins from 0.01 to 0.2 and is somewhat higher than predicted.

1 data table

Measured values of F2/ALPHA as a function of x. The second systematic error (DSYS) is that due to the model dependence and is the difference between the results obtained with PHOJET and TWOGAM. The full systematic error is the quadrature sum of the two systematic errors.


Study of the hadronic photon structure function F2(gamma) at LEP.

The L3 collaboration Acciarri, M. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 436 (1998) 403-416, 1998.
Inspire Record 472644 DOI 10.17182/hepdata.49392

The hadronic photon structure function F γ 2 is studied in the reaction e + e − →e + e − hadrons at LEP with the L3 detector. The data, collected from 1991 to 1995 at a centre-of-mass energy s ≃91 GeV, correspond to an integrated luminosity of 140 pb −1 . The photon structure function F γ 2 is measured in the Q 2 interval 1.2 GeV 2 ≤ Q 2 ≤9.0 GeV 2 and the x interval 0.002< x <0.2. F γ 2 shows a linear growth with ln Q 2 . The value of the slope α −1 d F γ 2 ( Q 2 )/dln Q 2 is measured to be 0.079±0.011±0.009.

3 data tables

No description provided.

No description provided.

No description provided.


A measurement of the photon structure function F2(gamma) at Q**2 = 6.8-GeV**2.

The AMY collaboration Kojima, T. ; Nozaki, T. ; Abe, K. ; et al.
Phys.Lett.B 400 (1997) 395-400, 1997.
Inspire Record 441558 DOI 10.17182/hepdata.28320

The photon structure function F 2 γ has been measured at an average Q 2 value of 6.8 GeV 2 using data collected by the AMY detector at the TRISTAN e + e − collider. The measured F 2 γ is compared with several QCD-based parton density models.

1 data table

No description provided.


A Measurement of the photon structure function F2(gamma) at an average Q**2 of 12-GeV**2/c**4

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys.C 69 (1996) 223-234, 1996.
Inspire Record 396884 DOI 10.17182/hepdata.47867

None

2 data tables

No description provided.

Low x domain.


A High Q**2 measurement of the photon structure function F2(gamma)

The AMY collaboration Sahu, S.K. ; Ebara, S. ; Nozaki, T. ; et al.
Phys.Lett.B 346 (1995) 208-216, 1995.
Inspire Record 392701 DOI 10.17182/hepdata.38361

The photon structure function F 2 γ has been measured at average Q 2 values of 73 and 390 GeV 2 using data collected by the AMY detector at the TRISTAN e + e − collider. F 2 γ is observed to be increasing as ln Q 2 . The x -dependence of F 2 γ , where x is the momentum fraction carried by the parton inside the photon, is also measured. The measurements are compared with several parton density models.

3 data tables

No description provided.

No description provided.

Errors contain both statistics and systematics.


Measurement of the photon structure function F2(gamma) and jet production at TRISTAN

The TOPAZ collaboration Muramatsu, K. ; Hayashii, H. ; Noguchi, S. ; et al.
Phys.Lett.B 332 (1994) 477-487, 1994.
Inspire Record 373856 DOI 10.17182/hepdata.38377

We have measured the photon structure function F 2 γ in the reaction e + e − → e + e − hadrons for average Q 2 values from 5.1 to 338 GeV 2 by using data collected by the TOPAZ detector at TRISTAN. The data have been corrected for detector effects and are compared with theoretical expectations based on QCD. The structure function F 2 γ increases as ln Q 2 , as expected. A sample of events with one or two distinct jets has been identified in the final state. Although two-jet events can be explained solely by the point-like perturbative part, one-jet events require a significant hadron-like part in addition.

7 data tables

No description provided.

No description provided.

No description provided.

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OBSERVATION OF SCALING OF THE PHOTON STRUCTURE FUNCTION F2 (gamma) AT LOW Q**2

The TPC/Two Gamma collaboration Aihara, H. ; Alston-Garnjost, M. ; Avery, R.E. ; et al.
Phys.Rev.Lett. 58 (1987) 97, 1987.
Inspire Record 233595 DOI 10.17182/hepdata.20136

The structure function F2γ for a quasireal photon has been measured in the reaction ee→eeX for Q2 in the range 0.2<Q2<7 GeV2, by use of 9200 multihadron events obtained with the TPC/Two-Gamma detector at the SLAC storage ring PEP. The data have been corrected for detector effects by a regularized unfolding procedure and are presented as F2γ(x,Q2). The structure function shows scaling in the region 0.3<Q2<1.6 GeV2, x<0.3, and rises for higher Q2 and x>0.1. Below Q2=0.3 GeV2, scaling breaks down in accordance with the finite cross-section bound for real photons.

4 data tables

Data read from graph.

Data read from graph.

Data read from graph.

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Measurement and QCD Analysis of the Photon Structure Function F2 (x, Q**2)

The PLUTO collaboration Berger, Christoph ; Genzel, H. ; Lackas, W. ; et al.
Nucl.Phys.B 281 (1987) 365, 1987.
Inspire Record 230592 DOI 10.17182/hepdata.33588

We present a measurement of the hadronic structure function F 2 γ ( x , Q 2 ) of the photon in the Q 2 range from 10 to 100 GeV 2 . Data were taken with the PLUTO detector at the e + e - storage ring PETRA. This measurement and previous PLUTO measurements in the Q 2 range of 1.5 to 16 GeV 2 are compared with higher order QCD calculations. The structure function is consistent with the predicted log Q 2 behaviour when charm contributions are subtracted. The x dependence can be well described for 0.1 < x < 0.9 by the regularization scheme of Antoniadis and Grunberg. Within their scheme the data yield a value of Λ MS = 183 + 65/ −40( stat. ) + 46/ −36( sys. ) MeV for the QCD scale parameter.

5 data tables

Data read from graph.

Data read from graph.

Data read from graph.

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Measurement of the photon structure function F2 (gamma) in the reaction e+ e- ---> e+ e- + hadrons at LEP

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, John ; et al.
Z.Phys.C 61 (1994) 199-208, 1994.
Inspire Record 358863 DOI 10.17182/hepdata.48474

We present measurements of the hadronic photon structure functionF2γ(x), in twoQ2 ranges with mean values of 5.9 GeV2 and 14.7 GeV2. The data were taken by the OPAL experiment at LEP, with\(\sqrt s\) close to theZ0 mass and correspond to an integratede+e− luminosity of 44.8 pb−1. In the context of a QCD-based model we find the quark transverse momentum cutoff separating the vector meson dominance (VMD) and perturbative QCD regions to be 0.27±0.10 GeV. We confirm that there is a significant pointlike component of the photon when the probe photon hasQ2>4 GeV2. Our measurements extend to lower values ofx than any previous experiment, and no increase ofF2γ(x) is observed.

2 data tables

Additional overall systematic error 5.9% not included.

Additional overall systematic error 5.9% not included.