Opportunities for heavy-ion physics at the large hadron collider LHC

Abstract

Abstract. This talk discusses extrapolations to the LHC of several, apparently universal trends, seen in the data on relativistic nucleus-nucleus collisions up to RHIC energies. In the soft physics sector, such extrapolations to the LHC are typically at odds with LHC predictions of the dynamical models, advocated to underlie multiparticle production up to RHIC energies. I argue that due to this, LHC is likely to be a discovery machine not only in the hard, but also in the soft physics sector.

Heavy-ion collisions at the LHC—Last call for predictions

“…This correspond to ≈17.5 produced charged hadrons per participant pair. These values are higher than those obtained by requiring that both limiting fragmentation and the trapezoidal shape of the pseudorapidity distribution persist at the LHC [28]. Our model predicts a characteristic violation of the apparently universal trend, seen up to maximum RHIC energy.…”

“…At LHC energies, due to higher initial energy density (or temperature) we expect an increase of the mean value of the string tension (κ) (see this section). The day 1 measurements at the LHC will include results on multiplicity distributions with important consequences for our understanding of matter produced in the collisions [27,28]. From our model calculations one expects dN ch PbPb dη ≈ 3500 at η = 0 in central (0-5%) Pb+Pb collision.…”

“…It should be noticed that b may be larger than 1 and that a color glass condensate (CGC) model calculation [192] shows a structure similar to (28): b = A[1 + B] −1 (for a discussion on general properties of (28) and on the CGC model, see [191]).…”

“…A simple way of testing ( 28) is by fixing the backward rapidity window, or n B , in the region of high particle density and move the forward window along the rapidity axis. We can rewrite equation (28)…”

Alice

“…When extrapolating from existing data to LHC energies we see the striking difference between the results obtained applying a saturation model or a fit in ln 2 √s . As discussed in detail in [18] and [19], the multiplicity measurement will by itself force us to either revisit the central ideas used to explain particle production at RHIC or face a violation of the universal structure observed in multiparticle production at lower energies. In either case, the very first nucleus-nucleus collisions at the LHC will already profoundly influence our understanding of the field.…”