No Arabic abstract
We study in detail the main features of the unitarized Regge model (CFKS), recently proposed to describe the small-$Q^2$ domain. It takes into account a two-component description with two types of unitarized contributions: one is the multiple Pomeron exchanges contribution, interacting with the large dipole size configurations, and the other one consists on a unitarized dipole cross section, describing the interaction with the small size dipoles. We compare the resulting dipole cross section to that from the saturation model (GBW).
In the neutrino DIS diffraction the charged current non-conservation gives rise to sizable corrections to the longitudinal structure function, $F_L$. These corrections is a higher twist effect enhanced at small-$x$ by the rapidly growing gluon density. The phenomenon manifests itself in abundant production of charm and strangeness by longitudinally polarized W bosons of moderate virtualities $Q^2lsim m_c^2$.
The contributions at the DIS2008 workshop in the working group on Diffraction and Vector Mesons are summarised.
High energy inclusive hadron production in the central kinematical region is analyzed within the models of unitarized pomeron. It is shown that the sum of multipomeron exchanges with intercept $alpha_P(0)>1$ reproduce qualitatively contribution of the triple pole (at $t=0$) pomeron to inclusive cross section. Basing on this analogy we then suggest a general form of unitarized pomeron contributions (in particular the dipole or tripole pomeron) to inclusive cross section. They lead to a parabolic form of the rapidity distribution giving $<n>propto ln^3s$ (tripole) or $<n>propto ln^2s$ (dipole). The models considered with suggested parametrization of $p_t$-dependence for cross sections well describe the rapidity distributions data in $pp$ and $bar pp$ interactions at energy $sqrt{s}geq 200$ GeV. The predictions for one particle inclusive production at LHC energies are given.
Higgs Effective Field Theory (HEFT) is deployed to study elastic vector-boson scattering at the high LHC energies. The interaction is strong over most of the parameter space, with the minimal Standard Model being a remarkable exception. One-loop HEFT complemented with dispersion relations and the Equivalence Theorem leads to two different unitarization methods which produce analytical amplitudes corresponding to different approximate solutions to the dispersion relations: the Inverse Amplitude method (IAM) and the N/D method. The partial waves obtained can show poles in the second Riemann sheet whose natural interpretation is that of dynamical resonances with masses and widths depending on the starting HEFT parameters. Different unitarizations yield qualitatively, and in many cases quantitatively, very similar results. The amplitudes obtained provide realistic resonant and nonresonant cross sections to be compared with and to be used for a proper interpretation of the LHC data.
In the framework of our model (GLM) for soft interaction with $alpha_{pom}(0)=0$, we propose a procedure based on Gribovs partonic interpretation of the Pomeron, which enables one to calculate the diffractive mass distributions in hadron-hadron scattering. Using the analogy with deep-inelastic scattering, we associate the Pomeron-quark interaction with the Good-Walker sector of the hadron-hadron scattering, and the Pomeron-gluon sector with the t-channel Pomeron interactions. We present predicted mass distributions for the LHC energies