52 research outputs found
Reggeon Field Theory for Large Pomeron Loops
We analyze the range of applicability of the high energy Reggeon Field Theory
derived in [1]. We show that this theory is valid as long as at any
intermediate value of rapidity throughout the evolution at least one of
the colliding objects is dilute. Importantly, at some values of the
dilute object could be the projectile, while at others it could be the target,
so that does not reduce to either or . 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 [3] and [4]. We also show
that, in its regime of applicability can be simplified. We derive the
simpler version of and in the large limit rewrite it in terms
of the Reggeon creation and annihilation operators. The resulting is
explicitly self dual and provides the generalization of the Pomeron calculus
developed in [4] 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.Comment: 38 pages, 4 figure
KLWMIJ Reggeon Field Theory beyond the large limit
We extend the analysis of KLWMIJ evolution in terms of QCD Reggeon fields
beyond leading order in the expansion. We show that there is only one
type of corrections to the leading order Hamiltonian discussed in \cite{last}.
These are terms linear in original Reggeons and quadratic in conjugate Reggeon
operators. All of these have the interpretation as vertices of the "`merging"'
type , where two Reggeons merge into one. Importantly, the
triple Pomeron merging vertex does not emerge from the KLWMIJ Hamiltonian. We
show that, although in the range of applicability of the KLWMIJ Hamiltonian
these merging terms are subleading in , in the dense-dense regime they all
become of the same (leading) order in . In this regime vertices involving
higher Reggeons are enhanced by inverse powers of the coupling constant.Comment: 25 page
Diffractive Dijet Production in Deep Inelastic Scattering and Photon-Hadron Collisions in the Color Glass Condensate
We study exclusive dijet production in coherent diffractive processes in deep
inelastic scattering and real (and virtual) photon-hadron (-h)
collisions in the Color Glass Condensate formalism at leading order. We show
that the diffractive dijet cross section is sensitive to the color-dipole
orientation in the transverse plane, and is a good probe of possible
correlations between the -dipole transverse separation vector \r
and the dipole impact parameter \b. We also investigate the diffractive dijet
azimuthal angle correlations and -distributions in -h
collisions and show that they are sensitive to gluon saturation effects in the
small- region. In particular, we show that the -distribution of
diffractive dijet photo-production off a proton target exhibits a dip-type
structure in the saturation region. This effect is similar to diffractive
vector meson production. Besides, at variance with the inclusive case, the
effect of saturation leads to stronger azimuthal correlations between the jets.Comment: 15 pages, 10 figures; v2: a clarifying Appendix added, 3 new plots
added, references added. The version to appear in PL
Soft photon and two hard jets forward production in proton-nucleus collisions
We calculate the cross section for production of a soft photon and two hard
jets in the forward rapidity region in proton-nucleus collisions at high
energies. The calculation is performed within the hybrid formalism. The
hardness of the final particles is defined with respect to the saturation scale
of the nucleus. We consider both the correlation limit of small momentum
imbalance and the dilute target limit where the momentum imbalance is of the
order of the hardness of the jets. The results depend on the first two
transverse-momentum-dependent (TMD) gluon distributions of the nucleus.Comment: 39 pages, 4 figure
Bose enhancement and the ridge
We point out that Bose enhancement in a hadronic wave function generically
leads to correlations between produced particles. We show explicitly, by
calculating the projectile density matrix in the Color Glass Condensate
approach to high-energy hadronic collisions, that the Bose enhancement of
gluons in the projectile leads to azimuthal collimation of long range rapidity
correlations of the produced particles, the so-called ridge correlations.Comment: 5 pages, 1 figure; v2: 6 pages, 1 figure, discussions enlarged and
technical details added, figure changed, final versio
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