Demierre, Ph.
H1
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A Direct determination of the gluon density in the proton at low x

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Nucl.Phys.B 449 (1995) 3-21, 1995.
Inspire Record 395643 DOI 10.17182/hepdata.44979

A leading order determination of the gluon density in the proton has been performed in the fractional momentum range $1.9 \cdot 10~{-3} < x_{g/p} < 0.18$ by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a kinematic region previously not accessible. The data show a considerable increase of the gluon density with decreasing fractional momenta of the gluons.

1 data table
Table 1

FG is gluon structure function. XPARTON here means the X of the gluon. For the experimental definitions of the XPARTON see paper.


rivet Analysis
A Study of the fragmentation of quarks in e- p collisions at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Nucl.Phys.B 445 (1995) 3-21, 1995.
Inspire Record 394793 DOI 10.17182/hepdata.44978

Deep inelastic scattering (DIS) events, selected from 1993 data taken by the H1 experiment at HERA, are studied in the Breit frame of reference. The fragmentation function of the quark is compared with those of \ee data. It is shown that certain aspects of the quarks emerging from within the proton in \ep interactions are essentially the same as those of quarks pair-created from the vacuum in \ee annihilation. The measured area, peak position and widthof the fragmentation function show that the kinematic evolution variable, equivalent to the \ee squared centre of mass energy, is in the Breit frame the invariant square of the four-momentum transfer. We comment on the extent to which we have evidence for coherence effects in parton showers.

6 data tables
Table 1

Distribution of the cosine of the Breit frame polar angle for data with the Breit frame energy flow selection. Statistical errors only.

Table 2

Distribution of the cosine of the Breit frame polar angle for data before the Breit frame energy flow selection. Statistical errors only.

Table 3

The fragmentation function for the current hemisphere of the Breit frame. Data are Breit frame energy flow selected only. Statistical errors only.

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Determination of the strong coupling constant from jet rates in deep inelastic scattering

The H1 collaboration Ahmed, T. ; Aid, S. ; Andreev, V. ; et al.
Phys.Lett.B 346 (1995) 415-425, 1995.
Inspire Record 380945 DOI 10.17182/hepdata.45050

Jet rates in deep inelastic electron proton scattering are studied with the H1 detector at HERA for momentum transfers squared between 10 and 4000 GeV 2 . It is shown that they can be quantitatively described by perturbative QCD in next to leading order making use of the parton densities of the proton and with the strong coupling constant α s as a free parameter. The measured value, α s ( M Z 2 ) = 0.123 ± 0.018, is in agreement both with determinations from e + e − annihilation at LEP using the same observable and with the world average.

1 data table
Table 1

Determination of ALP_S(MZ**2). Error contains both statistics and systematics.