Pomeron Coupling Research Articles

Reggeon exchange in the quark model

A formalism is presented for obtaining Regge-pole exchange amplitudes in the quark model. The Reggeon-quark couplings are determined by the electromagnetic and weak couplings of the quarks, through the vector dominance of the quark currents, exchange degeneracy and, for diffractive processes, f dominance of the pomeron coupling. The magnitudes of the Reggeon couplings are thus fixed by the vector-meson-photon coupling constant fomega gamma . It is shown that given fomega gamma a wide variety of successful predictions can be made, both of particle decay rates and of hadronic scattering amplitudes. The theoretical implications of the success of the scheme are examined briefly.

Dual unitarization scheme with several trajectories

Consequences of bootstrap with several input Regge trajectories are investigated. We find that in a general (without the duality-diagrams constraints) treatment of bootstrap, consistency requires the intercept of the output Pomeron pole in the one-dimensional case to be larger than one: ${\ensuremath{\alpha}}_{P}(0)>1$, a situation reminiscent of the one in Reggeon field theory. Symmetry breakings of the Pomeron couplings are discussed. These couplings coincide with those of the $f$-dominated Pomeron model of Carlitz, Green, and Zee (CGZ). The case when in the unitarity loops all possible trajectories are exchanged is also considered. Predictions of the dual unitary model for the slopes of differential cross sections for diffractive scattering are made which differ from those of the CGZ model. A comparison with the experimentally available data is performed.

A theoretical approach to low multiplicity diffractive dissociation

We investigate the dynamics of low mass inelastic diffractive production in the framework of the “1/N dual unitarization” scheme. The smallness of inelastic diffractive dissociation is explicitly demonstrated by incorporating a Deck type mechanism with the crucial planar bootstrap equation. Although both inelastic and elastic pomeron couplings are of the same order in 1/N, the origin for their smallness, however, is not identical. Our work further confirms the validity of the iterative procedure, where the elastic amplitude is first generated from only non-diffractive intermediate states (except possibly for central collisions). Using a previous study of the “Cylinder” strength, we present also a semi-quantitative results for the integrated cross-section for low multiplicity diffractive production and compare it with the elastic cross-section at very high energies.

Low mass diffractive dissociation in a simple t-dependent dual bootstrap model

The smallness of inelastic diffractive dissociation is explicitly demonstrated, in the framework of the “ 1 N dual unitarization” scheme, by incorporating a Deck type mechanism with the crucial planar bootstrap equation. Although both inelastic and elastic pomeron couplings are of the same order in 1 N , the origin for their smallness, however, is not identical.

Relative strengths of pomeron and other particle couplings

Relative strengths of pomeron and other particle couplings

Fdominance and final-state counting in multiperipheral cluster models

We discuss several problems associated with the formulation and use of multiperipheral cluster models and the closely related Reggeon-loop expansion in dual models. We present a method which unambiguously and uniquely counts final states, and combine it with conventional factorization to obtain a t-channel integral equation with Regge-pole solutions. These correctly counted solutions are used to estimate the error induced by various incorrect counting schemes. We then consider the relation between Reggeon and Pomeron poles, assuming the latter originate from crossed-loop or cylinder diagrams, and emphasize the tacit assumptions needed to obtain f-dominated Pomeron couplings. We find a Pomeron intercept of about 0.8. (AIP)

Model-independent bound on the triple-Pomeron pole coupling

We derive an upper bound on the triple-Pomeron coupling $g_{P}^{}{}_{}{}^{2}(0)$ assuming the actual Pomeron is a pole below one. Our result corresponds to an estimate of $g_{P}^{}{}_{}{}^{2}(0)$ obtained by Abarbanel, Chew, Goldberger, and Saunders on the basis of a multiperipheral model. We show that if indeed the bound is an estimate of $g_{P}^{}{}_{}{}^{2}(0)$, Pomeron exchange in multiparticle production should constitute a significant fraction of the total cross section. We indicate how this can be true even in the limit of vanishing Pomeron couplings. It is also shown how our calculation can be applied to obtain a bound on the "bare" triple-Pomeron coupling.

Local Loop Dominance in the Dual Unitarity Scheme

The unitary equation in the dual approach can be written as a sum over reggeon loop diagrams. We assume that in some definite regions in energy, only one diagram, with a definite number of loops dominates the sum. As consequences we obtain SU(M) symmetry for coupling constants, Gell-Mann Okubo formulae for mass breaking and exchange degeneracy for reggeon trajectories. We also derive relations connecting the Pomeron and reggeon intercepts with quantities referring to production of clusters. Predictions are given for the breaking of Pomeron couplings in reactions involving strange and charmed particles.

Symmetry breaking and duality diagrams in a multiparticle production model

Symmetry breaking is studied systematically in a multi-Regge resonance production model. Consistency of the planar bootstrap with broken symmetry requires ideal nonets to have equal spacing between ϱ, K ∗ and φ trajectories. Non-planar diagrams generate a leading vacuum singularity near one. Formulae relating symmetry breaking of the pomeron couplings and of produced particle multiplicities are given.

Pp Total Cross Section Rise with a Renormalized Romeron

The single-loop Pomeron diagram connected through the generalized optical theorem to two-cluster production is used to construct an integral equation. The infinite class . of Pomeron loop diagrams taken into account by this equation effectively renormalizes the Pomeron singularity. A simple pole Pomeron·at IXo=l is renormalized by this procedure into a j-plane pole-doublet and leads to a rising pp total cross section. Single or double-particle diffrac:tive dissociation has been one of several mechanisms proposed to account for the observed proton-proton total cross section rise above PL=50 Ge V / c.u- 4> It is found, however, that quantitative predictions from either one are insufficient5'- 7' to explain this experimental feature, although numerical results vary according to the chosen functional form and strength at t=O of the triple Pomeron coupling.8'· 9' In this work we start from a bare Pomeron trajectory a ( t) = a 0 +a' t ex­ changed between two diffractively produced fireballs, and assumed to control the triple-Regge region. 10' An integral equ~tion is then constructed to sum the class of (bare) Pomeron loop-diagrams that correspond to diffractive production of an unrestricted number of fireballs. This equation is (approximately) solved and the contribution to the elastic amplitude of the resulting renormalized Pomeron is obtained and compared to pp total cross section data. One secondary term rvs- 1/ 2 is added to extend the description of data down to PL=10GeV/c. Proton-proton scattering may produce an event with at least one large repidity gap separating groups of particles. If the energy is larger than some certain threshold, a minimum separation in rapidity is ensured between the fireballs. The cross section for two fireballs with masses squared s1 and s2 is given in the Regge asymptotic limit by1n' 12'

Bootstrap model with a bare Pomeron

The resolvent-kernel technique is used to obtain the inclusive distributions in a one-dimensional bootstrap model containing both pionization and diffraction. In the case where diffraction is described by a bare Pomeron with intercept less than one, we obtain an exact solution of the bootstrap equation for the single-particle distribution, which can display correct double- Regge behavior near x=0. For a Pomeron with intercept exactly one, we obtain a multifireball expansion for the inclusive distribution in powers of the Pomeron coupling constant. Comparison of the multifireball expansion for the bare Pomeron, with the exact solution, indicates that the expansion does not correctly describe the distribution near x=0. We discuss the solution of the n trajectory, one-dimensional bootstrap model and its relation to conventional treatments of the n-trajectory Chew-Pignotti model.

Pomeron couplings and the decays of ψ and ψ'

Assuming that the ψ(3095) and ψ'(3685) are φ c mesons, we estimate the effects on their decay modes of the dual model loop graphs which contain the quark line disconnected Pomeron contributions.

Is theψa "ring" state?

We propose that the newly discovered $\ensuremath{\psi}$ mesons lie on $C=\ensuremath{-}1$ partners of the daughter trajectories of the Pomeron. Consequently we consider them as excited closed string or ring states of dual or non-Abelian gauge theories. We obtain the mass formula ${{m}_{n}}^{2}=\frac{4n}{{\ensuremath{\alpha}}^{\ensuremath{'}}}$ for the spin 1 daughters of the Pomeron in terms of the universal Regge slope ${\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{\simeq}0.85$ Ge${\mathrm{V}}^{\ensuremath{-}2}$, and note that no new mass scale is needed to account for the $\ensuremath{\psi}$ masses (${m}_{\ensuremath{\psi}}\ensuremath{\simeq}{m}_{2}, {m}_{{\ensuremath{\psi}}^{\ensuremath{'}}}\ensuremath{\simeq}{m}_{3}$). Our model requires a new symmetry group such as color to account for the narrow width of the observed $\ensuremath{\psi}'\mathrm{s}$. However, the zero quark content of the ring states and the weakness of Pomeron couplings gives further suppression to $\ensuremath{\psi}$ photoproduction, hadronic $\ensuremath{\psi}$ production, and some decay modes.

A broken SU(4) scheme for pomeron couplings and the diffractive photo- and neutrino-production of charmed vector mesons

Conjecturing the existence of f c, the sixteenth member of the ideally mixed hexa-decimet tensor trajectories, we extend from SU(3) to SU(4) the idea of the f and f′ dominance of Pomeron couplings. Relations between diffractive cross-sections for processes with and without charmed particles are derived. These relations involve the intercepts of f, f′ and f c trajectories and are estimated in a model of exchange degenerate linear φ c-f c trajectory incorporating the new particles of mass 3.1 and 3.7 GeV. The low f c intercept leads to a strong suppression of cross-sections for φ c photo-production and F ∗ neutrino-production compared to ϱ production.

The peripheral impact parameter description of inelastic diffraction dissociation at very high energies

A simple peripheral impact parameter model for inelastic diffraction dissociation is used to describe both the very high energy exclusive process pp → p π +n and the inclusive process pp → pX. It is found that the width of the impact parameter profile has a small dependence on s/ M 2 which is compatible with a Regge shrinkage factor of the form ( s/ M 2) 0.17 t . It is suggested that the profile is independent of the number of particles produced, and that the non-vanishing of the triple pomeron coupling and the sharp t-behaviour of the inclusive distributions at small M 2 values is the generalization of the slope-mass correlation effect observed in exclusive processes.

A multi-pomeron model with zeros in the couplings

The violation of the Froissart bound resulting from repeated exchanges of pomerons in a multi-Regge model is avoided by assuming that some pomeron couplings vanish. The couplings can be chosen such that an input pomeron can produce an output pole coinciding with the input pomeron, and a two-pomeron cut. The main aim is to show that the structure of pomeron couplings can play an important role in calculations involving many pomerons

Behaviour of the proton-proton total cross section at ISR energies in the reggeon calculus

We study the behaviour of σ pp T at ISR energies in the Reggeon calculus with a bare triple Pomeron coupling non vanishing at q 2 = 0. The parameters are determined from elastic and inclusive data. A sizable increase of σ T with s can only be obtained when the bare Pomeron intercept is such that the renormalized Pomeron singularity is above one, in the forward direction.

Proton diffraction dissociation studies at the CERN ISR

Proton diffraction dissociation was studied at the ISR with a double-arm magnetic spectrometer close to the forward directions of the two ISR beams. Events with a single charged particle in one spectrometer and a jet in the opposite direction were found to be predominantly diffraction dissociation. In these events a positive correlation was observed between the mass and decay multiplicity of the fireball. The shape of the diffractive mass spectrum and its consistency with triple pomeron coupling were investigated at s = 31 GeV, 45 GeV and 53.4 GeV .

Models for high-energy inclusive processes and screening in deuterium

The screening correction to the high energy ( p lab > 10 GeV/ c) elastic hadron-deuteron scattering amplitude is discussed. It is found that the correction cannot completely be calculated using as input only the data for cross sections of inclusive reactions on free nucleons. Nevertheless measurements of high energy screening corrections provide sensitive tests for models of inclusive processes. In particular elastic screening does not dominate over the inelastic screening if, as indicated by recent fits, the triple pomeron coupling does not vanish for three mass-zero pomerons. If this is the case, the theory of high energy elastic scattering on heavier nuclei would have to be reconsidered. The discussion is illustrated by a numerical calculation for elastic πd scattering in the 10GeV–2000 GeV energy range.

On the self-consistent Pomeron pole

A model is considered in which a Pomeron is regarded as a self-consistent intercept one Regge pole resulting from a Bethe-Salpeter-like equation in Reggeon theory. The absorptive nature of a two Pomeron cut is crucial for realization of self-consistency. For zero mass Pomerons the model predicts the vanishing of the triple Pomeron coupling and softening of Pomeron cut contributions to inclusive reactions in triple and di-triple Regge regions.