The
F
2, F
G, R =
F
L
F
T
proton structure functions are derived in the QCD dipole picture. Assuming
k
T
and renormalization-group factorization, we relate deep-inelastic proton scattering to ...deep-inelastic onium scattering. We get a three-parameter fit of the 1994 H1 data in the low-
x, moderate
Q
2 range. The ratios
F
G
F
2
and
R are predicted without further adjustment. The dipole picture of BFKL dynamics is shown to provide a relevant model for quantitatively describing the proton structure functions at HERA. The predictions for
F
2 and
F
G
are compatible with the next-to-leading order DGLAP analysis, while
R is expected to be significantly lower at very small
x.
Using the QCD dipole picture of the hard BFKL pomeron, we derive the general expressions of the elastic and inelastic components of the proton diffractive structure functions. We obtain a good ...seven-parameter fit (including a secondary reggeon contribution) to data taken at HERA by the H1 and ZEUS Collaborations. The main characteristic features of the model in reproducing the data are discussed, namely the effective pomeron intercept, the scaling violations and the β-dependence. A difference obtained in the separate H1 and ZEUS fits leads us to analyze directly the differences between both measurements. Predictions on
R, the ratio of longitudinal to transverse photon cross sections are performed and lead to very large values at high beta and large virtuality
Q which may lead to a discrimination between models.
We consider the single chargino production at Tevatron
p
p
̄
→
ν
̃
i→
χ
̃
±
1l
i
∓
as induced by the resonant sneutrino production via a dominant R-parity violating coupling of type
λ′
ijk
L
i
Q
j
D
...k
c
. Within a supergravity model, we study the three leptons final state. The comparison with the expected background demonstrate that this signature allows to extend the sensitivity on the supersymmetric mass spectrum beyond the present LEP limits and to probe the relevant R-parity violating coupling down to values one order of magnitude smaller than the most stringent low energy indirect bounds. The trilepton signal offers also the opportunity to reconstruct the neutralino mass in a model independent way with good accuracy.
Using the colour dipole approach of the QCD perturbative (BFKL) Pomeron exchange in onium-onium scattering, we compute the cross section for small but hierarchically different onium sizes. A specific ...term dependent on the size-ratio is generated. In deep inelastic onium scattering it appears as a scaling-violation contribution to the quark structure function near the BFKL singularity. We find that the extension of the formalism for deep inelastic onium scattering to the proton structure function provides a remarkably good 3-parameter fit to HERA data at small
x with a simple physical interpretation in terms of the dipole formulation.
We present and discuss two different topics where Tevatron and HERA data can
be compared directly. A method allowing for a direct comparison of data with
theoretical predictions is proposed for ...forward jet production at HERA. An
application to the determination of the effective Pomeron intercept in the
BFKL-LO parametrization from $d\sigma/dx$ data at HERA leads to a good fit with
a significantly high effective intercept, $\alpha_P= 1.43 \pm 0.025 (stat.) \pm
0.025 (syst.)$. It is less than the value of the pomeron intercept using dijets
with large rapidity intervals obtained at Tevatron. In a second part of this
report, we make comparison between diffractive results at HERA and at Tevatron.
We first give the parton distributions in the pomeron extracted from HERA data,
and compare with hard single diffraction at Tevatron and diffractive dijets
with a leading antiproton data.
The $F_{2}$, $F_{G}$, $R=F_{L}/F_{T}$ proton structure functions are derived
in the QCD dipole picture of BFKL dynamics. We get a three parameter fit
describing the 1994 H1 proton structure function ...$F_{2}$ data in the low $x$,
moderate $Q^{2}$ range. Without any additional parameter, the gluon density and
the longitudinal structure functions are predicted.The diffractive dissociation
processes are also discussed, and a new prediction for the proton diffractive
structure function is obtained.
We present and discuss two different topics where Tevatron and HERA data can be compared directly. A method allowing for a direct comparison of data with theoretical predictions is proposed for ...forward jet production at HERA. An application to the determination of the effective Pomeron intercept in the BFKL-LO parametrization from \(d\sigma/dx\) data at HERA leads to a good fit with a significantly high effective intercept, \(\alpha_P= 1.43 \pm 0.025 (stat.) \pm 0.025 (syst.)\). It is less than the value of the pomeron intercept using dijets with large rapidity intervals obtained at Tevatron. In a second part of this report, we make comparison between diffractive results at HERA and at Tevatron. We first give the parton distributions in the pomeron extracted from HERA data, and compare with hard single diffraction at Tevatron and diffractive dijets with a leading antiproton data.
The \(F_{2}\), \(F_{G}\), \(R=F_{L}/F_{T}\) proton structure functions are derived in the QCD dipole picture of BFKL dynamics. We get a three parameter fit describing the 1994 H1 proton structure ...function \(F_{2}\) data in the low \(x\), moderate \(Q^{2}\) range. Without any additional parameter, the gluon density and the longitudinal structure functions are predicted.The diffractive dissociation processes are also discussed, and a new prediction for the proton diffractive structure function is obtained.
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