522 research outputs found
Lessons from LHC elastic and diffractive data
In the light of LHC data, we discuss the global description of all high
energy elastic and diffractive data, using a one-pomeron model, but including
multi-pomeron interactions. The LHC data indicate the need of a
behaviour, where is the gluon transverse momentum along the partonic
ladder structure which describes the pomeron. We also discuss tensions in the
data, as well as the dependence of the slope of in the
small domain.Comment: 5 pages, 3 figures, Proceedings of Diffraction 2014, Primosten,
Croatia, Sept. 10-1
Checking formalism for central exclusive production in the first LHC runs
We discuss how the early LHC data runs can provide crucial tests of the
formalism used to predict the cross sections of central exclusive production.Comment: 7 pages, 6 figures; Based on a talk by A.D. Martin at the CERN - DESY
Workshop "HERA and the LHC", 26 - 30 May 2008, CER
Information from leading neutrons at HERA
In principle, leading neutrons produced in photoproduction and deep-inelastic
scattering at HERA have the potential to determine the pion structure function,
the neutron absorptive cross section and the form of the pion flux. To explore
this potential we compare theoretical predictions for the x_L and p_t spectra
of leading neutrons, and the Q^2 dependence of the cross section, with the
existing ZEUS data.Comment: 17 pages, 8 figure
Photon-Photon Collisions with SuperChic
The SuperChic Monte Carlo generator provides a common platform for
QCD-mediated, photoproduction and photon-induced Central Exclusive Production
(CEP), with a fully differential treatment of soft survival effects. In these
proceedings we summarise the processes generated, before discussing in more
detail those due to photon-photon collisions, paying special attention to the
correct treatment of the survival factor. We briefly consider the
light-by-light scattering process as an example, before discussing planned
extensions and refinements for the generator.Comment: 6 pages, 2 figures. Submitted to proceedings of the PHOTON 2017
conferenc
Luminosity monitors at the LHC
We study the theoretical accuracy of various methods that have been proposed
to measure the luminosity of the LHC pp collider, as well as for Run II of the
Tevatron p barp collider. In particular we consider methods based on
(i) the total and forward elastic data, (ii) lepton-pair production and (iii)
W and Z production.Comment: 23 pages, Latex, 9 figure
Publisher Erratum: The Low soft-photon theorem again
It is shown that contrary to claims of Lebiedowicz et al. (Phys Rev D 105(1):014022, 2022) the formulated in the proper physical variables Low theorem (Low in Phys Rev 110(4):974–977, 1958) for soft photon emission does not require any modification. We also reject the criticism in Lebiedowicz et al. (2022) of the papers (Burnett and Kroll in Phys. Rev. Lett. 20:86–88,1968; Lipatov in Nucl Phys B 307:705–720, 1988). At the same time, we identify some inaccuracies in Burnett and Kroll (1968) in the presentation of the soft-photon theorem for the case of spin-one-half particles. We also point out shortcomings in consideration of the Low theorem in the classic textbooks (Berestetskii et al. in Quantum electrodynamics. Pergamon Press, Oxford, 1982; Lifshitz and Pitaevsky in Relativistic quantum theory, part 2, Fizmatlit, 2002)
Perturbative QCD Approach to Multiparticle Production
In this review we discuss the analytical perturbative approach, based on
perturbative QCD and Local Parton Hadron Duality (LPHD), and its application to
multiparticle production in jets in the semisoft region. Analytical formulae
are presented for various observables within the accuracy of the Modified
Leading Logarithmic Approximation (MLLA), i.e. with terms of relative order
taken into account systematically, and in some cases with
even higher accuracy. These predictions are confronted with existing
experimental data. Many details of the perturbative approach to multiple
hadroproduction have been consolidated in recent years, and the overall picture
is remarkably healthy. The prospects of future studies of the semisoft jet
physics are also discussed.Comment: LaTex, 153 pages, 54 figures available from the authors; to be publ.
by Int. Journal of Modern Physics
- …