GRANIITTI: A Monte Carlo Event Generator for High Energy Diffraction

Abstract

We describe the physics and computational power of GRANIITTI Monte Carlo event generator, a new fully multithreaded engine designed for high energy diffraction, written in modern C++. The emphasis is especially on the low-mass domain of central exclusive processes of the S-matrix, where exotic QCD phenomena such as glueballs are expected and holographic dualities with gravity may be tested. The generator includes photon-photon, photon-pomeron, pomeron-pomeron, Durham QCD model and Tensor pomeron model type scattering amplitudes and advanced spin analysis tools. The generator combines a full parametric resonance spectrum with continuum interference and forward + central spin correlations together with event-by-event eikonal screening loop and forward proton excitation kinematics. We demonstrate the state-of-the-art capabilities and show how the enigmatic `glueball filter' observable is driven by spin polarization.

81 pages, 25 figures, v2: minor modifications

References in corpus (6)

• LHAPDF6: parton density access in the LHC precision era
• The Pomeron and Gauge/String Duality
• Event-by-event gluon multiplicity, energy density and eccentricities at RHIC and LHC
• Measurement of diffraction dissociation cross sections in pp collisions at sqrt(s) = 7 TeV
• Measurement of the exclusive $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$ process in proton--proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Longitudinal structure function from logarithmic slopes of $F_2$ at low $x$