Pomeron Coupling Research Articles

Phi meson electroproduction at low transferred momentum

The electroproduction of phi meson is analyzed. The amplitude consist of two terms, the soft and the hard pomeron terms. it is assumed, that both pomerons are Regge poles. In the present approach, the two pomeron amplitude for the photoproduction processes is extended to construct an amplitude for the electroproduction processes by introducing the photon virtual mass ( . The residues of the two poles become functions of ( . These functions are extracted by fitting the differential cross section ( ) of the extended model at constant energy to the experimental data using the chi- square method. At each , the hard and the soft terms are multiplied by the factors and to match the data. The vertices of the pomeron coupling to the interacting particles are calculated by the dimensions of the vertices which are related to the masses of the interacting particles at each vertex.

Coherent J/ψ photoproduction in hadronic heavy-ion collisions

Significant excesses of $J/\ensuremath{\psi}$ yield at very low transverse momentum (${p}_{T}<0.3$ GeV/$c$) were observed by the ALICE and STAR collaborations in peripheral hadronic $A+A$ collisions. This is a sign of coherent photoproduction of $J/\ensuremath{\psi}$ in violent hadronic interactions. Theoretically, the photoproduction of $J/\ensuremath{\psi}$ in hadronic collisions raises questions about how spectator and nonspectator nucleons participate in the coherent reaction. We argue that the strong interactions in the overlapping region of incoming nuclei may disturb the coherent production, leaving room for different coupling assumptions. The destructive interference between photoproduction on ions moving in opposite directions also needs to be included. This paper presents calculations of $J/\ensuremath{\psi}$ production from coherent photon-nucleus ($\ensuremath{\gamma}+A\ensuremath{\rightarrow}J/\ensuremath{\psi}+A$) interactions in hadronic $A+A$ collisions at BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider energies with both nucleus and spectator coupling hypotheses. The integrated yield of coherent $J/\ensuremath{\psi}$ as a function of centrality is found to be significantly different, especially towards central collisions, for different coupling scenarios. Differential distributions as a function of transverse momentum, azimuthal angle, and rapidity in different centrality bins are also shown, and found to be more sensitive to the Pomeron coupling than to the photon coupling. These predictions call for future experimental measurements to help better understand the coherent interaction in hadronic heavy-ion collisions.

On Regularized Trace Formula of Gribov Semigroup Generated by the Hamiltonian of Reggeon Field Theory in Bargmann Representation

In Intissar (J Math Anal Appl 305(2):669–689, 2005), the second author have considered the Gribov operator $${\mathbb {H}}_{\lambda '} = \lambda ' \mathbb {S} + {\mathbb {H}}_{\mu ,\lambda }$$ acting on Bargmann space where $$ \mathbb {S} = a^{*2} a^{2}$$ and $$ {\mathbb {H}}_{\mu ,\lambda } =\mu a^*a + i \lambda a^*(a+a^*)a$$ with $$i^{2} = -1$$ and $$(\lambda ^{'}, \mu , \lambda ) \in \mathbb {R}^{3}$$ . Here a and $$a^{*}$$ are the standard Bose annihilation and creation operators satisfying the commutation relation $$[a, a^{*}] = \mathbb {I}$$ . In Reggeon field theory, the real parameters $$\lambda {'}$$ is the four coupling of Pomeron, $$\mu $$ is Pomeron intercept, $$\lambda $$ is the triple coupling of Pomeron and $$i^{2} = -1$$ . He had given an approximation of the semigroup $$e^{-t{\mathbb {H}}_{\lambda '}}$$ generated by the operator $${\mathbb {H}}_{\lambda '}$$ . In particular, he had obtained an estimate approximation in trace norm of this semigroup by the unperturbed semigroup $$e^{-t\lambda '\mathbb {S}}$$ . In Intissar (J Math Anal Appl 437:59–70, 2016), he had regularized the operator $${\mathbb {H}}_{\mu ,\lambda }$$ by $$\lambda ''{\mathbb {G}}$$ where $${\mathbb {G}} = a^{*3} a^{3}$$ , i.e he had considered $${\mathbb {H}}_{\lambda ''} = \lambda '' {\mathbb {G}} + {\mathbb {H}}_{\mu ,\lambda }$$ where $$\lambda ''$$ is the magic coupling of Pomeron. In this case, he had established an exact relation between the degree of subordination of the non-self-adjoint perturbation operator $${\mathbb {H}}_{\mu ,\lambda }$$ to the unperturbed operator $${\mathbb {G}}$$ and the number of corrections necessary for the existence of finite formula of the regularized trace. The goal of the work of the authors in this article consists to study the trace of the semigroup $$e^{-t\mathbb {}H_{\lambda ''}}$$ , in particular to give an asymptotic expansion of this trace as $$t \rightarrow 0^{+}$$ .

The ground state of the Pomeron and its decays to light mesons and photons

The problem of the timelike Pomeron coupling to light mesons and photons is considered in light of available data on high-energy meson-proton scattering. Possible correspondence of $f_2(1950)$ resonance to the ground state of the Pomeron is argued.

Regularized trace formula of magic Gribov operator on Bargmann space

In this article, we obtain a regularized trace formula for magic Gribov operator H=λ″G+Hμ,λ acting on Bargmann space whereG=a⁎3a3 and Hμ,λ=μa⁎a+iλa⁎(a+a⁎)a Here a and a⁎ are the standard Bose annihilation and creation operators and in Reggeon field theory, the real parameters λ″ is the magic coupling of Pomeron, μ is Pomeron intercept, λ is the triple coupling of Pomeron and i2=−1. By applying some abstract results of Sadovnichii–Podol'skii (2002) [23], we give the number of corrections sufficient for the existence of finite formula of the trace of concrete magic Gribov's operator.

The next-to-leading order vertex for a forward jet plus a rapidity gap at high energies

We present the results for the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the Balitsky–Fadin–Kuraev–Lipatov (BFKL) formalism at next-to-leading order (NLO). We handle the real emission contributions making use of the high energy effective action proposed by Lipatov, valid for multi-Regge and quasi-multi-Regge kinematics. This result is important since it allows, together with the NLO non-forward gluon Green function, to perform NLO studies of jet production in diffractive events (Mueller–Tang dijets, as a well-known example).

Diffraction at the LHC

We show that the diffractive pp (and p\bar{p}) data (on \sigma_tot, d\sigma_el/dt, proton dissociation into low-mass systems, \sigma^D(low M), and high-mass dissociation, d\sigma/d(\Delta\eta)) in a wide energy range from CERN-ISR to LHC energies, may be described in a two-channel eikonal model with only one `effective' pomeron. By allowing the pomeron coupling to the diffractive eigenstates to depend on the collider energy (as is expected theoretically) we are able to explain the low value of \sigma^D(low M) measured at the LHC. We calculate the survival probability, S^2, of a rapidity gap to survive `soft rescattering'. We emphasize that the values found for S^2 are particularly sensitive to the detailed structure of the diffractive eigenstates.

PHOTON – POMERON COUPLING IN HADRONIC INTERACTIONS

Pomeron coupling to photons has been analyzed. As the pomeron assumed to couple to hadrons through their constituent quarks and since the photon has no constituent quarks it's coupling to the pomeron is not well known. We proposed that the pomeron may couple to two photons in away similar to that of pseudo scalar particles (π0, η, ή ). To justify our model we have calculated the photon-proton total cross section in the region where a single pomeron is dominated. For completeness the contribution from reggeons exchange at low energies has been included. A comparison with the data shows a good agreement .

Role of Anomalous Quark-Gluon Chromomagnetic Interaction in Hadron Physics

We calculate the contribution arising from nonperturbative quark-gluon chro- momagnetic interaction to the high energy total quark-quark cross section. The estimation obtained within the instanton model of QCD vacuum leads to the conclusion that this type of interaction gives the dominating contribution to the Pomeron coupling with the light quarks and to gluon distribution in light hadrons at small virtualities of quarks and gluons.

High-energy photon-hadron scattering in holographic QCD

This article provides an in-depth look at hadron high-energy scattering by using gravity dual descriptions of strongly coupled gauge theories. Just like deeply inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) serve as clean experimental probes into nonperturbative internal structure of hadrons, elastic scattering amplitude of a hadron and a (virtual) photon in gravity dual can be exploited as a theoretical probe. Since the scattering amplitude at sufficiently high energy (small Bjorken $x$) is dominated by parton contributions ($=\mathrm{\text{Pomeron contributions}}$) even in strong coupling regime, there is a chance to learn a lesson for generalized parton distribution (GPD) by using gravity dual models. We begin with refining derivation of the Brower--Polchinski--Strassler--Tan (BPST) Pomeron kernel in gravity dual, paying particular attention to the role played by the complex spin variable $j$. The BPST Pomeron on warped spacetime consists of a Kaluza--Klein tower of 4D Pomerons with nonlinear trajectories, and we clarify the relation between Pomeron couplings and the Pomeron form factor. We emphasize that the saddle-point value ${j}^{*}$ of the scattering amplitude in the complex $j$-plane representation is a very important concept in understanding qualitative behavior of the scattering amplitude. The total Pomeron contribution to the scattering is decomposed into the saddle-point contribution and at most a finite number of pole contributions, and when the pole contributions are absent (which we call saddle-point phase), kinematical variable $(q,x,t)$-dependence of $\mathrm{ln}(1/q)$ evolution and $\mathrm{ln}(1/x)$ evolution parameters ${\ensuremath{\gamma}}_{\mathrm{eff}}$ and ${\ensuremath{\lambda}}_{\mathrm{eff}}$ in DIS and $t$-slope parameter $B$ of DVCS in HERA experiment are all reproduced qualitatively in gravity dual. All of these observations shed a new light on modeling of GPD. Straightforward application of those results to other hadron high-energy scattering is also discussed.

All-loop calculation of the Reggeon field theory amplitudes via stochastic model

The evolution equations for Green functions of the Reggeon Field Theory (RFT) are equivalent to those of the inclusive distributions for the reaction–diffusion system of classical particles. We use this equivalence to obtain numerically Green functions and amplitudes of the RFT with all loop contributions included. The numerical realization of the approach is described and some important applications including total and elastic proton–proton cross sections are studied. It is shown that the loop diagram contribution is essential but can be imitated in the eikonal cross section description by changing the Pomeron intercept. A role of the quartic Pomeron coupling which is an inherent part of the stochastic model is shown to be negligible for available energies.

Role of anomalous chromomagnetic interaction in Pomeron and Odderon structures and in gluon distribution

We calculate the contribution arising from nonperturbative quark-gluon chromomagnetic interaction to the high-energy total quark-quark cross section and to gluon distributions in nucleon. The estimation obtained within the instanton model of QCD vacuum leads to the conclusion that this type of interaction gives the dominating contribution to the Pomeron coupling with the light quarks and to gluon distribution in light hadrons at small virtualities of quarks and gluons. We argue that the Odderon, which is the P = C = −1 partner of the Pomeron, is governed by the spin-flip component related to nonperturbative three-gluon exchange induced by anomalous quark-gluon chromomagnetic interaction.

QCD motivated approach to soft interactions at high energies: Nucleus–nucleus and hadron–nucleus collisions

In this paper we consider nucleus–nucleus and hadron–nucleus reactions in the kinematic region: g A 1 / 3 G 3 P exp ( Δ P Y ) ⩾ 1 and G 3 P 2 exp ( Δ P Y ) < 1 , where G 3 P is the triple Pomeron coupling, g is the vertex of Pomeron nucleon interaction, and 1 + Δ P denotes the Pomeron intercept. We find that in this kinematic region the traditional Glauber–Gribov eikonal approach is inadequate. We show that it is necessary to take into account inelastic Glauber corrections, which cannot be expressed in terms of the nucleon–nucleon scattering amplitudes. We derive the nucleus–nucleus scattering amplitude in the wide range of energies where α P ′ Y ≪ R A 2 , where this amplitude does not depend on the details of the nucleon–nucleon interaction at high energy. In the formalism we present, the only (correlated) parameters that are required to describe the data are Δ P , G 3 P and g. These parameters were taken from our description of the nucleon–nucleon data at high energies Gotsman et al. (2008) [1]. The predicted nucleus modification factor is compared with RHIC Au–Au data at W = 200 GeV . Estimates for LHC energies are presented and discussed.

Pomeron-Quark Coupling from Charge ConjugationInvariance

Based on the charge conjugation invariance and the vacuum propertyof the Pomeron, we point out that the commonly used vector vertexof the Pomeron coupling to quark is incorrect since it contradictswith the Pomeron property. We also claim that the soft Pomeroncould be a tensor glueball ξ(2230) with quantum numbersIGJPC = 0+2++ and total decay widthΓtot≃100 MeV, which lies on the soft Pomerontrajectory αp = 1.08+0.20t. Therefore, the couplingvertex of the soft Pomeron to quark should be tensorial which isinvariant under the charge conjugation and can explain why theinadequate vector coupling, γμ, of the soft Pomeron toquark is successful in dealing with Pomeron physics.

The process $\gamma(^*) + p \to \eta_c + X$ : a test for the perturbative QCD odderon

The rates of inclusive photo- and electroproduction of the eta_c meson: gamma* + p -> eta_c + X are calculated in the triple Regge region, integrated over the diffractive mass X. For the Regge exchanges we use the hard Pomeron and Odderon, both being calculated in the framework of perturbative QCD. The integrated cross-section depends upon the coupling of the BFKL pomeron to two $C=-1$ odderons, and it is found to be of the order 60 pb for photoproduction and 1.5 pb at Q^2=25 GeV^2.

On the triple-Pomeron vertex in perturbative QCD

We estimate the size of the triple Pomeron vertex in perturbative QCD and compare with the phenomenological value extracted from Regge fits to experimental data. For simplicity, the results of the QCD analysis are taken in the large-N_c limit. We find that the perturbative triple Pomeron coupling is of the same order of magnitude as the observed one. We also estimate the size of the Pomeron self energy and its contribution to the renormalization of the Pomeron intercept. The effect is very small, in agreement with previous nonperturbative estimates.

Chirality violation in QCD Reggeon interactions

The appearance of the triangle graph infra-red axial anomaly in reduced quark loops contributing to QCD triple-regge interactions is studied. In a dispersion relation formalism, the anomaly can only be present in the contributions of unphysical triple discontinuities. In this paper an asymptotic discontinuity analysis is applied to high-order feynman diagrams to show that the anomaly does indeed occur in sufficiently high-order reggeized gluon interactions. The reggeon states involved must contain reggeized gluon combinations with the quantum numbers of the anomaly (winding-number) current. A direct connection with the well-known U(1) problem is thus established. Closely related diagrams that contribute to the pion/pomeron and triple pomeron couplings in color superconducting QCD are also discussed.

Deeply virtual Compton scattering at smallx

The authors calculate the cross section of the deeply virtual Compton scattering at large energies and intermediate momentum transfers. In recent years the study of the deeply virtual Compton scattering (DVCS) became one of the most popular topics in QCD due to the fact that it is determined by skewed parton distributions which generalize usual parton densities introduced by Feynman. These new probes of the nucleon structure are accessible in exclusive processes such as DVCS and potentially they can give more information than the traditional parton densities. In this paper the authors consider the small-x DVCS where the energy of the incoming virtual photon E is very large in comparison to its virtuality Q{sup 2}. To be specific, they calculate the DVCS amplitude in the region s >> Q{sup 2} >> -t >> m{sup 2} where s = 2mE, m is the nucleon mass, and t is the momentum transfer. The DVCS in this region is a semihard process which can be described by the BFKL (Balitsky-Fadin-Kuraev-Lipatov) pomeron. It turns out that at large momentum transfer the coupling of the BFKL pomeron to the nucleon is essentially equal to the Dirac form factor of the nucleon F{sub 1}(t), so themore » DVCS amplitude in the region can be calculated without any model assumptions. The results obtained in this region can be used for the estimates of the amplitude at experimentally accessible energies where one or more conditions in Eq. (1) are relaxed. To be specific, they have in mind the HERA kinematics where x {approx} 10{sup -2} {divided_by} 10{sup -4}, Q{sup 2} {ge} 6 GeV{sup 2}, and -t {approx} 1 {divided_by} 5 GeV{sup 2}. Since there are only model predictions for the small-x DVCS in current literature, even the approximate calculations of the cross section in QCD are very timely.« less

Spin effects in diffractive Q $$\bar Q$$ production and compass experimentproduction and compass experiment

We calculate the double spin asymmetry of the diffractive Q $$\bar Q$$ and vector meson leptoproduction at COMPASS energies. We analyze dependences of the asymmetry on the structure of the Pomeron-proton coupling. It is shown that it is difficult to study the spin structure of the Pomeron coupling with the proton from the A ll asymmetry. The A lT asymmetry might be an appropriate object for this investigation.

Spin effects in diffractive J/ $\Psi$ leptoproduction and the structure of Pomeron coupling

We calculate the cross section and \(A_{\mathrm{ll}}\) asymmetry of the diffractive J/\(\Psi\) leptoproduction for a simple model of a Pomeron coupling with a proton, which contains the \(\gamma^{\alpha}\) term and a spin-dependent part. It is shown that the asymmetry caused by the Pomeron coupling \(\propto \gamma^{\alpha}\) does not vanish for nonzero \(|t|\). The sensitivity of the polarized diffractive J/\(\Psi\) production to the spin-dependent part of the Pomeron coupling is found to be rather weak. As a result, it is difficult to study the structure of the Pomeron coupling with the proton in future polarized diffractive experiments on the J/\(\Psi\) production.