Exclusive central production of dijets at hadronic colliders

in AIP Conference Proceedings (2009), 1105

Axions & Polarisation of Quasars

Poster (2008, May 21)

The spin-flip amplitude in the impact-parameter representation

in European Physical Journal. Special Topics (2008)

The impact-parameter representation of the spin-flip amplitude of hadron elastic scattering is examined in different unitarisation schemes, taking the Born term of the spin-flip amplitude from the Dubna ... [more ▼]

The impact-parameter representation of the spin-flip amplitude of hadron elastic scattering is examined in different unitarisation schemes, taking the Born term of the spin-flip amplitude from the Dubna Dynamical Model (DDM). It is shown that the basic properties of the unitarisation schemes are independent of the functional form used for unitarisation but heavily depend on the asymptotic value of the unitarised amplitude. [less ▲]

Unitarisation and black-disk limit at the LHC in the presence of a hard pomeron

in Physics Letters B (2008), 662(5), 417-423

Recent models of soft diffraction include a hard pomeron pole besides the usual soft term. Such models violate the black-disk limit around Tevatron energies, so that they need to be supplemented by a ... [more ▼]

Recent models of soft diffraction include a hard pomeron pole besides the usual soft term. Such models violate the black-disk limit around Tevatron energies, so that they need to be supplemented by a unitarisation scheme. Two standard schemes are considered in this Letter, and we show that they lead to an uncertainty at the LHC much larger than previously estimated. We also examine the signature of unitarisation on various small-t observables, the slope in t of the elastic cross section, or the ratio of the real to imaginary parts of the scattering amplitude, and show that the existence of a unitarised hard pomeron in soft scattering may be confirmed by LHC data. (C) 2008 Elsevier B.V. All rights reserved. [less ▲]

Exclusive J/psi and Upsilon hadroproduction and the QCD odderon

in Physical Review. D (2007), 75(9),

We study pp and pp collisions which lead to the exclusive production of J/psi or Upsilon from the pomeron-odderon and the pomeron-photon fusion. We calculate scattering amplitudes of these processes in ... [more ▼]

We study pp and pp collisions which lead to the exclusive production of J/psi or Upsilon from the pomeron-odderon and the pomeron-photon fusion. We calculate scattering amplitudes of these processes in the lowest-order approximation and in the framework of k(perpendicular to) factorization. We present estimates of cross sections for the kinematic conditions of the Tevatron and of the LHC. [less ▲]

Saturation effects in elastic scattering at the LHC

in Bartels, J.; Borras, K.; Diehl, M. (Eds.) et al 12th International Conference on Elastic and Diffractive Scattering (Blois Workshop) - Forward Physics and QCD (2007)

New contributions to heavy-quarkonium production

in Physics Letters B (2006), 633(2-3), 301-308

We reconsider quarkonium production in a field-theoretical setting and we show that the lowest-order mechanism for heavy-quarkonium production receives in general contributions from two different cuts ... [more ▼]

We reconsider quarkonium production in a field-theoretical setting and we show that the lowest-order mechanism for heavy-quarkonium production receives in general contributions from two different cuts. The first one corresponds to the usual colour-singlet mechanism. The second one has not been considered so far. We treat it in a gauge-invariant manner, and introduce new 4-point vertices, suggestive of the colour-octet mechanism. These new objects enable us to go beyond the static approximation. We show that the contribution of the new cut can be as large as the usual colour-singlet mechanism at high P-T for J/psi. In the psi' case, theoretical uncertainties are shown to be large and agreement with data is possible. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Soft data and the hard pomeron

in Nuclear Physics B-Proceedings Supplements (2006, February), 152

We show that the introduction of an additional, hard, singularity in soft forward amplitudes enables one to improve considerably the fits using a simple-pole structure for the soft pomeron.

Saturation effects in diffractive scattering at LHC energies

in Kolganova, E.; Sissakian, A.; Kozlov, G. (Eds.) ICHEP 2006: Proceedings (2006)

Saturation effects in pp scattering in the impact-parameter representation

in Nuclear Physics B-Proceedings Supplements (2005, September), 146

The impact of unitarity is considered in different approaches to saturation in impact-parameter space. The energy and momentum-transfer dependence of the total and differential cross sections and of the ... [more ▼]

The impact of unitarity is considered in different approaches to saturation in impact-parameter space. The energy and momentum-transfer dependence of the total and differential cross sections and of the ratio of the real to imaginary parts of the scattering amplitude are obtained in a model that includes soft and hard pomeron contributions, coupled to hadrons via the electromagnetic form factor. It is shown that the hard pomeron may significantly contribute to soft physics at the LHC. A similar conclusion can also be reached in the framework of non-linear approaches to unitarisation of the BFKL pomeron. [less ▲]