Jets and energy flow in photon - proton collisions at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Z.Phys.C 70 (1996) 17-30, 1996.
Inspire Record 402890 DOI 10.17182/hepdata.44935

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to $\overline{p}p$ data and QCD calculations. The comparisons show that the $\gamma p$ events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections $d\sigma/dE_T~{jet}$ and $d\sigma/d\eta~{jet}$ are measured.

3 data tables

No description provided.

Additional overall systematic error of 26 pct.

Additional overall systematic error of 26 pct.


Measurement of the total photon-proton cross-section and its decomposition at 200-GeV center-of-mass energy

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Z.Phys.C 69 (1995) 27-38, 1995.
Inspire Record 399015 DOI 10.17182/hepdata.44969

We present a new measurement of the total photoproduction cross section performed with the H1 detector at HERA. For an average centre of mass energy of 200GeV a value of $\sigma_{tot}~{\gamma{p}}= 165\pm2\pm11\mu$b has been obtained. A detailed analysis of the data in adequate kinematic regions enabled a decomposition of the total cross section in its elastic, single diffractive dissociation and remaining non-diffractive parts, based on safe assumptions on the double diffractive dissociation contribution.

2 data tables

No description provided.

Total GAMMA P cross section.


Transverse energy and forward jet production in the low x regime at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Phys.Lett.B 356 (1995) 118-128, 1995.
Inspire Record 396365 DOI 10.17182/hepdata.44901

The production of transverse energy in deep inelastic scattering is measured as a function of the kinematic variables $x$ and $Q~2$ using the H1 detector at the ep collider HERA. The results are compared to the different predictions based upon two alternative QCD evolution equations, namely the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) and the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equations. In a pseudorapidity interval which is central in the hadronic centre of mass system between the current and the proton remnant fragmentation region the produced transverse energy increases with decreasing $x$ for constant $Q~2$. Such a behaviour can be explained with a QCD calculation based upon the BFKL ansatz. The rate of forward jets, proposed as a signature for BFKL dynamics, has been measured.

10 data tables

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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

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


Measurement of the e+ and e- induced charged current cross-sections at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Z.Phys.C 67 (1995) 565-576, 1995.
Inspire Record 395960 DOI 10.17182/hepdata.44972

The cross sections for the charged current processes ${e~{-}p}\rightarrow{\nu_e+hadrons}$ and, for the first time, ${e~{+}p}\rightarrow{\overline{\nu}_e+hadrons}$ are measured at HERA for transverse momenta larger than 25 GeV.

2 data tables

No description provided.

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The Gluon density of the proton at low x from a QCD analysis of F2

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Phys.Lett.B 354 (1995) 494-505, 1995.
Inspire Record 395814 DOI 10.17182/hepdata.44945

We present a QCD analysis of the proton structure function $F_2$ measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of $F_2$ in the range $2\cdot 10~{-4}<x<3\cdot 10~{-2}$ and compared with an approximate solution of the QCD evolution equations. The gluon density is found to rise steeply with decreasing $x$.

3 data tables

No description provided.

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Leptoquarks and compositeness scales from a contact interaction analysis of deep inelastic e+- p scattering at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.
Phys.Lett.B 353 (1995) 578-588, 1995.
Inspire Record 394404 DOI 10.17182/hepdata.44997

A contact interaction analysis is presented to search for new phenomena beyond the Standard Model in deep inelastic $e~\pm p \rightarrow e~\pm \, hadrons$ scattering. The data are collected with the H1 detector at HERA and correspond to integrated luminosities of $0.909 \ {\rm pb}~{-1}$ and $2.947 \ {\rm pb}~{-1}$ for electron and positron beams, respectively. The differential cross sections $d\sigma / dQ~2$ are measured in the $Q~2$ range bet\-ween $160 \ \GeV~2$ and $20,000 \ \GeV~2$. The absence of any significant deviation from the Standard Model prediction is used to constrain the couplings and masses of new leptoquarks and to set limits on electron--quark compositeness scales and on the radius of light quarks.

2 data tables

Additional overall normalization error of 3.5 pct due to systematic errors of the luminosity measurement.

Additional overall normalization error of 1.8 pct due to systematic errors of the luminosity measurement.


Inclusive parton cross-sections in photoproduction and photon structure

The H1 collaboration Ahmed, T. ; Aid, S. ; Andreev, V. ; et al.
Nucl.Phys.B 445 (1995) 195-218, 1995.
Inspire Record 394176 DOI 10.17182/hepdata.44975

Photoproduction of 2-jet events is studied with the H1 detector at HERA. Parton cross sections are extracted from the data by an unfolding method using leading order parton-jet correlations of a QCD generator. The gluon distribution in the photon is derived in the fractional momentum range $0.04\le x_\gamma \le 1$ at the average factorization scale $75$ GeV$~2$.

3 data tables

No description provided.

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Gluon density of the photon (alpha is the fine structure constant).


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

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

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

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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First Measurement of the Deep--Inelastic Structure of Proton Diffraction

The H1 collaboration Ahmed, T. ; Aid, S. ; Andreev, V. ; et al.
Phys.Lett.B 348 (1995) 681-696, 1995.
Inspire Record 393286 DOI 10.17182/hepdata.45003

A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton scattering. The diffractive contribution to the proton structure function is evaluated as a function of the appropriate deep-inelastic scattering variables using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. The dependence of this contribution on x-pomeron is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of a factorised structure function is presented. This structure function is observed to be consistent with scale invariance.

19 data tables

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