# The "Ridge" in Proton-Proton Scattering at 7 TeV

Abstract : One of the most important experimental results for proton-proton scattering at the LHC is the observation of a so-called "ridge" structure in the two particle correlation function versus the pseudorapidity difference $\Delta\eta$ and the azimuthal angle difference $\Delta\phi$. One finds a strong correlation around $\Delta\phi=0$, extended over many units in $\Delta\eta$. We show that a hydrodynamical expansion based on flux tube initial conditions leads in a natural way to the observed structure. To get this result, we have to perform an event-by-event calculation, because the effect is due to statistical fluctuations of the initial conditions, together with a subsequent collective expansion. This is a strong point in favour of a fluid-like behavior even in $pp$ scattering, where we have to deal with length scales of the order of 0.1 fm.
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Journal articles
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http://hal.in2p3.fr/in2p3-00837670
Contributor : Sylvie Flores <>
Submitted on : Monday, June 24, 2013 - 9:42:44 AM
Last modification on : Friday, January 3, 2020 - 4:30:07 PM

### Citation

Klaus Werner, Iu. Karpenko, T. Pierog. The "Ridge" in Proton-Proton Scattering at 7 TeV. Physical Review Letters, American Physical Society, 2011, 106, pp.122004. ⟨10.1103/PhysRevLett.106.122004⟩. ⟨in2p3-00837670⟩

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