Search

The goal of this white paper is to give a comprehensive overview of the rich field of forward physics. We discuss the occurrences of BFKL re-summation effects in special final states, such as Mueller-Navelet jets, jet-gap-jets, and heavy quarkonium production. It further addresses TMD factorization at low x and the manifestation of a semi-hard saturation scale in (generalized) TMD PDFs. More theoretical aspects of low-x physics, probes of the quark-gluon plasma, as well as the possibility to use photon-hadron collisions at the LHC to constrain hadronic structure at low x, and the resulting complementarity between LHC and the EIC are also presented. We also briefly discuss diffraction at colliders as well as the possibility to explore further the electroweak theory in central exclusive events using the LHC as a photon-photon collider. [ABSTRACT FROM AUTHOR]

We present a review of the recent theoretical and experimental developments related to the field of diffraction, parton saturation, and forward physics. We first discuss our present understanding of the proton structure in terms of quarks and gluons, the degrees of freedom of quantum chromodynamics. We then focus on some of the main results on diffraction at the HERA electron–proton collider in DESY, Germany, at the Tevatron proton–antiproton collider at Fermilab, Batavia, US, and at the CERN Large Hadron Collider (LHC) proton–proton and nucleus–nucleus collider, which is located in Geneva, Switzerland. We also present a selected amount of results on diffraction and photon exchanges that can be done at the LHC experiments and at a future Electron Ion Collider (EIC) to be built in the US at Brookhaven National Laboratory, New York. [ABSTRACT FROM AUTHOR]

We describe some of the future measurements to be performed by the CMS, TOTEM and ATLAS collaborations on hard diffraction in order to understand better the structure of the Pomeron. We also describe the prospects concerning the search for quartic γγγγ anomalous couplings and discuss a possible interpretation for the existence of a new particle decaying into two photons at a mass of about 750 GeV. [ABSTRACT FROM AUTHOR]

We present some physics topics that will allow us to constrain the Pomeron structure at the LHC in terms of gluon and quark densities using the dijet and γ+ events and tagged protons in AFP (ATLAS) and CMS-TOTEM. We also discuss the possibility to test the BFKL dynamics using jet-gap-jet events. [ABSTRACT FROM AUTHOR]

We present possible measurements on forward physics and diffraction that can be accomplished at the LHC. [ABSTRACT FROM AUTHOR]

We present the project to install new forward proton detectors in the CMS and ATLAS experiments called CT-PPS and AFP respectively. [ABSTRACT FROM AUTHOR]

In this short review, we describe some of the results on diffraction from the Tevatron and give some prospects for the LHC. In particular, we discuss the search for exclusive events at the Tevatron and their importance for the LHC program. We finish by presenting the project of installing forward detectors in the ATLAS Collaboration at 220 and 420 m. [ABSTRACT FROM AUTHOR]

I give a brief introduction to diffraction in lepton-hadron and hadron-hadron collisions, the subject of this special issue of the International Journal of Modern Physics A. [ABSTRACT FROM AUTHOR]

A recently proposed parametrization for the deep inelastic diffractive cross-section is used to describe the H1 '94 data. We find two possible solutions and discuss them in details. [ABSTRACT FROM AUTHOR]

We discuss the different models of central diffractive production of the Higgs boson at the Tevatron and the LHC. We also describe how the models can be tested using diffractive production data being taken at the Tevatron. We finally discuss the advantages of using diffractive events to reconstruct the mass of the Higgs boson especially at the LHC. PACS: 12.38.-t – 12.38.Qk [ABSTRACT FROM AUTHOR]

We present the full next-to-leading order (NLO) prediction for the jet-gap-jet cross section at the LHC within the BFKL approach. We implement, for the first time, the NLO impact factors in the calculation of the cross section. We provide results for differential cross sections as a function of the difference in rapidity and azimuthal angle betwen the two jets and the second leading jet transverse momentum. The NLO corrections of the impact factors induce an overall reduction of the cross section with respect to the corresponding predictions with only LO impact factors. We note that NLO impact factors feature a logarithmic dependence of the cross section on the total center of mass energy which formally violates BFKL factorization. We show that such term is one order of magnitude smaller than the total contribution, and thus can be safely included in the current prediction without a need of further resummation of such logarithmic terms. Fixing the renormalization scale μR according to the principle of minimal sensitivity, suggests μR about 4 times the sum of the transverse jet energies and provides smaller theroretical uncertainties with respect to the leading order case. [ABSTRACT FROM AUTHOR]

We study the LHC sensitivity to new broad neutral resonances produced in two-photon fusion and decaying to a top quark pair, γγ → t t ¯ . This is probed in central exclusive t t ¯ production in proton-proton collisions, pp → pt t ¯ p . We use the tagging of the intact protons by PPS (CMS) and AFP (ATLAS) and consider the semi-leptonic t t ¯ channel. The sensitivity is also mapped onto a set of dimension-8 γγt t ¯ operators in the large mass limit. Using the kinematical correlations between the intact protons and the reconstructed t t ¯ system, we obtain a sensitivity to the couplings of the dimension-8 operators of 1.4 10−11 GeV−4 at 95% CL. The sensitivity to the anomalous couplings is significantly improved down to about 7 10−12 GeV−4 if the proton time-of-flight is known with a precision of 20 ps in future measurements. The 95% CL sensitivity to broad neutral resonances reaches masses of order 1500 GeV when using timing information. [ABSTRACT FROM AUTHOR]