# What's the potential of the LHC's heavy ion experiment?

RHIC has been the dominant player in heavy ion physics, producing tantalizing evidence in support of the entropy/viscocity formula from AdS/CFT. What's the potential of the LHC's Pb ion collsions? What can it achieve which RHIC can't? What measurements will be improved?

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## 1 Answer

A lot of what the LHC hopes to achieve in this area is described in a paper by Carlos Salgado, so I'd suggest you take a look at that. In summary:

• Collisions of nuclei yield much better data about parton saturation and the color glass condensate than collisions of individual nucleons. LHC p-Pb runs will allows us to study the high-energy behavior of the CGC.
• The kinematic range of high-energy nucleon-nucleus collisions extends down to values of Björken $x$ as small as $10^{-6}$ (compared to $10^{-3}$ for RHIC), which expands our knowledge of the nuclear parton distributions (e.g. whether and how well they factorize into individual nucleon PDFs)
• Asymmetric collisions in particular allow measurements of certain characteristics of the nuclear PDFs independent of uncertainties in the proton/neutron PDFs
• Jet quenching and "quarkonia suppression" (essentially jet quenching where the jet progenitors are bound states of heavy quarks) can be used as a probe of the QGP at higher energies and densities than were accessible at RHIC
• The LHC presents the first opportunity for collisions of multi-hadron systems (i.e. nuclei) with energies exceeding 1 TeV. So in general, if there is anything new and cool to be discovered at those energies, this is where we will find it.
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