Morgado, R.E.
ZEUS
E- P --> 2JET E- X
Max results
Sort by Reverse order

Showing 2 of 2 results

Measurement of $\alpha_S$ from Jet Rates in Deep Inelastic Scattering at HERA

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 363 (1995) 201-216, 1995.
Inspire Record 400436 DOI 10.17182/hepdata.44947

Jet production in deep inelastic scattering for $120<Q~2<3600$GeV$~2$ has been studied using data from an integrated luminosity of 3.2pb$~{-1}$ collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the $\gamma~*$-parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to ${\cal O}$($\alpha_{s}$~2$) perturbative QCD calculations, allow a precise determination of $\alpha_{s}(Q)$ in three $Q~2$-intervals. The values are consistent with a running of $\alpha_{s}(Q)$, as expected from QCD. Extrapolating to $Q=M_{Z~0}$ yields $\alpha_{s}(M_{Z~0}) = 0.117\pm0.005(stat)~{+0.004}_{-0.005}(syst_{exp}) {\pm0.007}(syst_{theory})$.

3 data tables
Table 1

2+1 jet rate as a function of ycut the jet algorithm cut-off value. Statistical errors only.

Table 2

Measured values of Lambda-QCD in the MS Bar scheme and alpha_s as a function of Q**2. The second systematic uncertainty is related to the theoretical uncertainties .

Table 3

Strong coupling constant alpha_s extrapolated to the Z0 mass.


Dijet cross-sections in photoproduction at HERA

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 348 (1995) 665-680, 1995.
Inspire Record 392980 DOI 10.17182/hepdata.44999

Dijet production by almost real photons has been studied at HERA with the ZEUS detector. Jets have been identified using the cone algorithm. A cut on xg, the fraction of the photon energy participating in the production of the two jets of highest transverse energy, is used to define cross sections sensitive to the parton distributions in the proton and in the photon. The dependence of the dijet cross sections on pseudorapidity has been measured for xg $\ge 0.75$ and xg $< 0.75$. The former is sensitive to the gluon momentum density in the proton. The latter is sensitive to the gluon in the photon. The cross sections are corrected for detector acceptance and compared to leading order QCD calculations.

2 data tables
Table 1

Direct photon di-jet cross section.. Data are for two (or more) jets.. Second systematic error is due to energy scale uncertainty.

Table 2

Resolved photon di-jet cross section.. Data are for two (or more) jets.. Second systematic error is due to energy scale uncertainty.