Forward Jet Production Research Articles

Forward jet production in deep inelastic scattering at HERA

Forward jet production in deep inelastic scattering at HERA

Forward jet and particle production at HERA

Single particles and jets in deeply inelastic scattering at low x are measured with the H1 detector in the region away from the current jet and towards the proton remnant, known as the forward region. Hadronic final state measurements in this region are expected to be particularly sensitive to QCD evolution effects. Jet cross sections are presented as a function of Bjorken- x for forward jets produced with a polar angle to the proton direction, θ jet, in the range 7° < θ jet < 20°. Azimuthal correlations are studied between the forward jet and the scattered lepton. Charged and neutral single particle production in the forward region are measured as a function of Bjorken- x, in the range 5° < θ < 25°, for particle transverse momenta larger than 1 GeV. QCD based Monte Carlo predictions and analytical calculations based on BFKL, CCFM and DGLAP evolution are compared to the data. Predictions based on the DGLAP approach fail to describe the data, except for those which allow for a resolved photon contribution.

BFKL physics in dijet production at the LHC

The production in hadron-hadron collisions of jet pairs with large rapidity separation and comparable modest transverse momentum is, in principle, described by the perturbative QCD BFKL equation. The measurement of such jet pairs appears well suited to the LHC detectors, with their ability to detect forward jets. We present predictions for dijet cross sections and correlations obtained using a BFKL Monte Carlo which allows kinematic and other subleading effects to be incorporated. The enhanced phase space for gluon emission at the LHC makes the BFKL behavior somewhat easier to observe than at the Tevatron, although kinematic effects are still important. The production of forward jets in association with heavy Higgs bosons via the gauge boson fusion mechanism is also studied and compared with QCD dijet production.

Azimuthal dependence of forward-jet production in DIS in the high-energy limit

As a signal for the BFKL Pomeron in small-x deep inelastic $ep$ scattering, we calculate the azimuthal dependence of the inclusive cross section of forward jets relative to the outgoing electron. For not very large differences in rapidity between the current jet and the forward jet the cross section peaks at $\pi/2$. For increasing rapidity BFKL dynamics predicts a decorrelation in the azimuthal dependence between the electron and the forward jet.

Forward Jet Production at DESY HERA in the LowxRegime in Next-to-Leading Order

The production of forward jets of transverse momentum ${p}_{T}(j)\ensuremath{\approx}Q$ and large momentum fraction ${x}_{\mathrm{jet}}\ensuremath{\gg}x$ probes the onset of Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics at DESY HERA. A full $O({\ensuremath{\alpha}}_{s}^{2})$ calculation of the inclusive forward jet cross section is presented and compared to the expected BFKL cross section. The kinematical region populated by these events and the scale dependence of the fixed order perturbative QCD cross sections are discussed.

QCD corrections to jet cross sections in DIS

Next-to-leading order corrections to jet cross sections in deep inelastic scattering at HERA are studied. The predicted jet rates allow for a precise determination of $\alpha_s(\mu_R)$ at HERA over a wide range of $\mu_R$. We argue, that the ``natural'' renormalization and factorization scale is set by the average $k_T^B$ of the jets in the Breit frame and suggest to divide the data in corresponding $<k_T^B>$ intervals. Some implications for the determination of the gluon density and the associated forward jet production in the low $x$ regime at HERA are briefly discussed.

QCD corrections to jet cross sections in DIS*

Next-to-leading order corrections to jet cross sections in deep inelastic scattering at HERA are studied. The predicted jet rates allow for a precise determination of α ,( μ R ) at HERA over a wide range of μ R . We argue that the “natural” renormalization and factorization scale is set by the average k T B of the jets in the Breit frame and suggest dividing the data into corresponding 〈 k T B 〉 intervals. Some implications for the determination of the gluon density and the associated forward jet production in the low x regime at HERA are briefly discussed.

Associated jet production at HERA

We compare the BFKL prediction for the associated production of forward jets at HERA with fixed-order matrix element calculations taking into account the kinematical cuts imposed by experimental conditions. Comparison with H1 data of the 1993 run favours the BFKL prediction. As a further signal of BFKL dynamics, we propose to look for the azimuthal dependence of the forward jets.

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

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.