Reggeon field theory for large Pomeron loops

Abstract

Abstract:We analyze the range of applicability of the high energy Reggeon Field Theory H RFT derived in [1]. We show that this theory is valid as long as at any intermediate value of rapidity η throughout the evolution at least one of the colliding objects is dilute. Importantly, at some values of η the dilute object could be the projectile, while at others it could be the target, so that H RFT does not reduce to either H JIM W LK or H KLW M IJ . When both objects are dense, corrections to the evolution not accounted for in [1] become important. The same limitation applies to other approaches to high energy evolution available today, such as for example [2,3] and [4][5][6]. We also show that, in its regime of applicability H RFT can be simplified. We derive the simpler version of H RFT and in the large N c limit rewrite it in terms of the Reggeon creation and annihilation operators. The resulting H RFT is explicitly self dual and provides the generalization of the Pomeron calculus developed in [4-6] by including higher Reggeons in the evolution. It is applicable for description of 'large' Pomeron loops, namely Reggeon graphs where all the splittings occur close in rapidity to one dilute object (projectile), while all the merging close to the other one (target). Additionally we derive, in the same regime expressions for single and double inclusive gluon production (where the gluons are not separated by a large rapidity interval) in terms of the Reggeon degrees of freedom.

NLO JIMWLK evolution unabridged

“…The prime example is the operator representing the Reggeized gluon, which played a very important role in the development of high energy evolution ideas, especially in the perturbative domain. Another example of an interesting nonsinglet observable, is inclusive gluon production amplitude, which is invariant only under the vector subgroup of SU L (N c ) × SU R (N c ) [35]. Recently ref.…”

“…However some interesting observables, like single gluon inclusive production require the knowledge of observables which are singlets only under the vector subgroup of SU L (N c )×SU R (N c ) [35]. It is thus useful to generalize the Hamiltonian so that it generates correct evolution of such operators.…”

CGC/saturation approach for high energy soft interactions: ‘soft’ Pomeron structure and $$v_{n}$$ v n in hadron and nucleus collisions from Bose–Einstein correlations

“…In building our model we rely on the BFKL Pomeron calculus, since the relation to diffractive physics is more evident in this approach. However, we are aware that the CGC/saturation approach gives a more general pattern [101][102][103][104]. In Refs.…”

“…In addition in Refs. [103,104] it is shown that for such Y , we can safely use the Mueller-Patel-Salam-Iancu (MPSI) approach [106][107][108][109], which allows us to calculate the contribution to the resulting BFKL Pomeron Green function (see Fig. 14a):…”

CGC/saturation approach for soft interactions at high energy: long range rapidity correlations

“…The BFKL Pomeron calculus turns out to be close to the old Reggeon theory [80], so, for calculating the inclusive characteristics of multiparticle production, we can apply the Mueller diagram technique [81]. The relation between these two approaches has not yet been established, but they are equivalent [74][75][76][77] where BFKL denotes the intercept of the BFKL Pomeron.…”