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In this paper we discuss the inclusive \\[J/\\psi \\] production in proton–proton collisions from fusion of three pomerons. We demonstrate that this mechanism gets dominant contribution from the region which can be theoretically described by CGC/saturation approach. Numerically, it gives a substantial contribution to the \\[J/\\psi \\] production, and is able to describe the experimentally observable shapes of the rapidity, momenta and multiplicity distributions. The latter fact provides a natural explanation of the experimentally observed enhancement of multiplicity distribution in \\[J/\\psi \\] production.

A bstract We initiate a study of asymptotic detector operators in weakly-coupled field theories. These operators describe measurements that can be performed at future null infinity in a collider experiment. In a conformal theory they can be identified with light-ray operators, and thus have a direct relation to the spectrum of the theory. After a general discussion of the underlying physical picture, we show how infrared divergences of general detector operators can be renormalized in perturbation theory, and how they give rise to detector anomalous dimensions. We discuss in detail how this renormalization can be performed at the intersections of the Regge trajectories where non-trivial mixing occurs, which is related to the poles in anomalous dimensions at special values of spin. Finally, we discuss novel horizontal trajectories in scalar theories and show how they contribute to correlation functions. Our calculations are done in the example of ϕ 4 theory in d = 4 − ϵ dimensions, but the methods are applicable more broadly. At the Wilson-Fisher fixed point our results include an explicit expression for the Pomeron light-ray operator at two loops, as well as a prediction for the value of the Regge intercept at five loops.

A bstract We generalize Regge theory to correlation functions in conformal field theories. This is done by exploring the analogy between Mellin amplitudes in AdS/CFT and S-matrix elements. In the process, we develop the conformal partial wave expansion in Mellin space, elucidating the analytic structure of the partial amplitudes. We apply the new formalism to the case of four point correlation functions between protected scalar operators in Super Yang Mills, in cases where the Regge limit is controlled by the leading twist operators associated to the pomeron-graviton Regge trajectory. At weak coupling, we are able to predict to arbitrary high order in the ’t Hooft coupling the behaviour near J  = 1 of the OPE coefficients between the external scalars and the spin J leading twist operators. At strong coupling, we use recent results for the anomalous dimension of the leading twist operators to improve current knowledge of the AdS graviton Regge trajectory — in particular, determining the next and next to next leading order corrections to the intercept. Finally, by taking the flat space limit and considering the Virasoro-Shapiro S-matrix element, we compute the strong coupling limit of the OPE coefficient between two Lagrangians and the leading twist operators of spin J .

A bstract Within the colour dipole picture for deep inelastic scattering at small Bjorken x , we study the production of a pair of relatively hard jets via coherent diffraction. By “relatively hard” we mean that the transverse momenta of the two jets — the quark ( q ) and the antiquark ( q ¯ ) generated by the decay of the virtual photon — are much larger than the target saturation momentum Q s ( Y ℙ ) evaluated at the rapidity gap Y ℙ . We argue that the typical final-state configurations are such that the hard q q ¯ dijets are accompanied by a semi-hard gluon jet, with a transverse momentum of the order of Q s ( Y ℙ ). The presence of this third jet ensures that the scattering is strong and thus avoids the strong suppression of exclusive (hard) dijet production due to colour transparency. For such “2+1” jet configurations, we demonstrate that both the emission of the semi-hard gluon and its scattering with the hadronic target can be factorised in terms of an effective gluon-gluon dipole. This effective description, originally proposed in [ 1 – 7 ], builds a bridge between the colour dipole picture and the transverse-momentum dependent (TMD) version of the collinear factorisation: the cross-section for diffractive 2+1 jets can be written as the product between a hard factor describing the q q ¯ dijets and a semi-hard factor expressing the unintegrated gluon distribution of the Pomeron. The latter is controlled by gluon dipole scattering in the black disk limit and hence is strongly sensitive to gluon saturation. By integrating out the kinematics of the 3 jets, we obtain the q q ¯ g contribution to the diffractive structure function in collinearly-factorised form.

In this paper we extend our recent non perturbative functional renormalization group analysis of Reggeon Field Theory to the interactions of Pomeron and Odderon fields. We establish the existence of a fixed point and its universal properties. This analysis, allows to connect the nonperturbative infrared region (large transverse distances) with the UV region of small transverse distances where the high energy limit of perturbative QCD applies. We discuss the implications of result for the existence of an Odderon in high energy scattering.

We present current and ongoing research aimed at identifying Pomeron effects at the LHC in both the weak and strongly coupled regimes of QCD.

In a contribution to the volume {\\it A Passion for Physics}, a collection of essays in honor of Geoffrey Chew's sixtieth birthday, I wrote, together with A. Capella, Uday Sukhatme, and Tran Thanh Van {\\it The Pomeron Story.} This is a follow-up to that contribution. This sequel also serves as an opportunity to acknowledge my gratitude to Geoff as a PhD student under his tutelage.

A bstract The Checkerboard conformal field theory is an interesting representative of a large class of non-unitary, logarithmic Fishnet CFTs (FCFT) in arbitrary dimension which have been intensively studied in the last years. Its planar Feynman graphs have the structure of a regular square lattice with checkerboard colouring. Such graphs are integrable since each coloured cell of the lattice is equal to an R-matrix in the principal series representations of the conformal group. We compute perturbatively and numerically the anomalous dimension of the shortest single-trace operator in two reductions of the Checkerboard CFT: the first one corresponds to the Fishnet limit of the twisted ABJM theory in 3D, whereas the spectrum in the second, 2D reduction contains the energy of the BFKL Pomeron. We derive an analytic expression for the Checkerboard analogues of Basso-Dixon 4-point functions, as well as for the class of Diamond-type 4-point graphs with disc topology. The properties of the latter are studied in terms of OPE for operators with open indices. We prove that the spectrum of the theory receives corrections only at even orders in the loop expansion and we conjecture such a modification of Checkerboard CFT where quantum corrections occur only with a given periodicity in the loop order.

A bstract We initiate the study of Regge theory in a bottom-up holographic model for QCD in the Veneziano limit, where the backreaction of the quarks to the gluon dynamics is included. We determine the parameters of the model by carrying out a precise fit to the meson spectrum in QCD. The spectrum for spin-one and pseudoscalar mesons is well reproduced. We then generalise the model to incluce higher spin fields in the bulk trajectories dual to the Pomeron and meson Regge trajectories at the boundary. With this setting, we fit the masses of the mesons with spins J = 2, 3, and 4, as well as the experimental data of the total cross-sections σ ( γγ → X ), σ ( γp → X ) and σ ( pp → X ). For the cross sections we obtain a χ d . o . f 2 of 0 . 74 for a total of 199 experimental points.

Recently BESIII collaboration discovered a charged strange hidden-charm state Zcs(3985) in the Ds-D∗0+Ds∗-D0 spectrum. A higher Zcs′ state coupling to D¯s∗-D∗0 is expected by SU(3)-flavor symmetry, and their bottom partners are anticipated by heavy quark flavor symmetry. Here we study the photoproduction of these exotic states and investigate carefully the background from Pomeron exchange. Our results indicate that the maximal photoproduction cross section of strange partner is around 1–2 orders of magnitude smaller than that of the corresponding non-strange states. The possibility of searching for them in future electron-ion colliders (EIC) is briefly discussed.