High-energy Total Cross Sections Research Articles

Comments on high-energy total cross sections in QCD

We discuss how hadronic total cross sections at high energy depend on the details of QCD, namely on the number of colours Nc and the quark masses. We find that while a “Froissart”-type behaviour σtot∼Blog2⁡s is rather general, relying only on the presence of higher-spin stable particles in the spectrum, the value of B depends quite strongly on the quark masses. Moreover, we argue that B is of order O(Nc0) at large Nc, and we discuss a bound for B which does not become singular in the Nf=2 chiral limit, unlike the Froissart–Łukaszuk–Martin bound.

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.

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.

Various total cross-sections for electron impact on , and

Cross-sections for the impact of electrons having energy Ei =50 - 5000 eV are evaluated for polyatomic molecules \(\), \(\), \(\), \(\), \(\) and \(\). Total (complete) cross-sections and total inelastic cross-sections are calculated for these targets by employing the atomic optical potentials and additivity rules. A variant of our previous work, to be called MAR-SC has been developed for molecules such as the present ones, where two approximately independent scattering centres can be identified. We find a good general accord of our theoretical values with various experimental data. Also given presently is an analytical fit \(\), incorporating polarizability \(\), for the high energy total cross-sections for 18-electron targets. Tentative upper and lower limits for the electron molecule total ionization cross-sections are identified and a break-up into elastic and inelastic contributions is exhibited.

Various total cross-sections for electron impact on

Cross-sections for the impact of electrons having energy E i = 50-5000 eV are evaluated for polyatomic molecules C 2 H 2 , C 2 H 4 , C 2 H 6 , CH 3 OH, CH 3 F and CH 3 NH 2 . Total (complete) cross-sections and total inelastic cross-sections are calculated for these targets by employing the atomic optical potentials and additivity rules. A variant of our previous work, to be called MAR-SC has been developed for molecules such as the present ones, where two approximately independent scattering centres can be identified. We find a good general accord of our theoretical values with various experimental data. Also given presently is an analytical fit Q T = A (α o /E i ) B , incorporating polarizability α o , for the high energy total cross-sections for 18-electron targets. Tentative upper and lower limits for the electron molecule total ionization cross-sections are identified and a break-up into elastic and inelastic contributions is exhibited.

Quark-quark scattering contributions to high-energy total cross sections

It is shown that total hadronic cross sections are described well by considering single- and double-scattering contributions from quark-quark scattering. With an energy-dependent form suggested by Regge theory, all high-energy total cross sections can be fitted successfully and efficiently using a small number of free parameters.

T-duality considerations for hadronic strings

We show that a simple account of hadronic high energy total cross sections and of the observed masses and flavor-gauge-like couplings of the familiar vector mesons is obtained in a hadronic string model suggested by QCD in the limit of a large number of colors. Our picture involves a Minkowski space which, in addition to the well-established continuous one time and three space dimensions, is endowed with an extra discrete space dimension involving a minimal two-point lattice with a spacing of order ${10}^{\ensuremath{-}14}$ cm in one of the two $T$-dual pictures. New mesonic states with characteristic decay modes are expected in such a picture.

Non-perturbative QCD treatment of high energy hadron-hadron scattering

The model of the stochastic vacuum is applied in order to evaluate soft high energy hadron-hadron scattering. The parameters determined from hadron spectroscopy and lattice gauge calculations allow to calculate high energy total and elastic cross sections. The same mechanism which leads to confinement gives rise to a string-string interaction in high energy scattering.

On the coherence between high-energy total cross-section data when compared with general principles

We perform an essentially model-independent study of the internal coherence between high-energy total cross-section data by using classes of functions satisfying general principles. Our study is practically independent of the ϱ-parameter values. Our general analysis, made without any fit, reveals certain inconsistencies in the existing set of high-energy data. Some of these inconsistencies are eliminated by giving up arbitrary assumptions sometimes made in “fitology”. We conclude that the ln 2 s increase of total cross-sections at high energies is clearly favoured when compared with the other possible behaviours.

The Ne-Ne interatomic potential revisited

The neon-neon interaction has been re-examined in the light of new data, both theoretical and experimental. Because of recent interest in solids at very high pressures, a new accurate potential is presented with particular interest paid to its highly repulsive region. A potential in HFD-B form incorporating the most recent dispersion coefficients was fitted to accurate viscosity data and high-energy scattering beam data. The potential is able to predict a wide range of macroscopic (second virial coefficients, viscosity, thermal conductivity, diffusion and 0 K binding energy) and microscopic properties (spectroscopic differential and high-energy total cross sections). The potential is extended to very short range by extrapolating to united atom perturbation results.

The neon–argon potential revisited

The neon–argon interaction has been reexamined in the light of new data, both theoretical and experimental. Two recent potentials have been analyzed as to their ability to predict both macro- and microscopic properties. Both of these fail to give a complete description of the interaction. A new simple potential is presented which accurately predicts a wide range of properties including high and low energy total cross sections, differential cross section, as well as second virials, viscosity, and diffusion. New combining rules have been tested and are found to be consistent with the new potential.

A temporarily freeSU 6 gauge field theory model for strong interactions

An analysis of experimental facts in low- and high-energy hadron interactions and theoretical results in gauge field theory leads to the conclusion that theSU6 totally spontaneously broken, temporary free gauge field model is a natural candidate for a description of strong hadron interactions. The model is based on the observed massive vector mesons and fermions. It is shown that the Higgs sector can be chosen in such a manner that—even after totalSU6 symmetry breaking—there survives a global symmetrySU2×U 1 s ×U 1 c ×U 1 b ×U 1 t which coincides with the observed isospin, strangeness, charm, beauty and top symmetry. The renormalization group analysis indicates that the model is temporarily free. It is shown that all vector mesons reggeize and their parent and daughter Regge trajectories are calculated in the leading-logarithm approximation. It is shown also that all fundamental fermions which can be taken either in vector or adjoint representation also reggeize. Due to temporary freedom the model possesses the scaling properties and enables a perturbative analysis of high-energy of processes. Since the model is based on observed hadrons the analysis of exclusive processes is considerably facilitated. It is shown, in particular, that the model predicts a new form of baryon-baryon and baryon-antibaryon high-energy total cross-section: it is noteworthy that the obtained cross sections are decreasing for moderately high energy and increasing for higher energies in a remarkable agreement with experimental data in the energy interval 10 GeV\(\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{< } \sqrt s \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle\thicksim}$}}{< } \)30 000 GeV.

An improved potential for Ar–Kr

An accurate intermolecular potential of the HFD-C form is proposed which appears to be the best representation of the Ar–Kr interaction. The potential, which possesses the correct long range behavior, predicts a wide variety of macroscopic and microscopic data. It is consistent with accurate second virial, viscosity, and diffusion coefficients. Differential scattering and low as well as high energy total cross section data are accurately predicted.

Heavy quarks and the measured surplus in the high-energy total photoproduction cross section

A recent experiment at Fermilab with tagged photon beam has extended the total-cross-section measurements ${\ensuremath{\sigma}}_{T}(\ensuremath{\gamma}p)$ to ${E}_{\ensuremath{\gamma}}=180$ GeV. In an earlier work, we have applied the core-valence quark model, using light quarks only, together with vector-meson dominance to describe ${\ensuremath{\sigma}}_{T}(\ensuremath{\gamma}p)$ up to 10 GeV. We have now extended our model by including the heavy-quark contribution, and in spite of this addition we find a definiency of 2-5 \ensuremath{\mu}b in ${\ensuremath{\sigma}}_{T}(\ensuremath{\gamma}p)$ in the high-energy region. Calculations within the framework of other models fail to account for the surplus in the experimental data. On extending the model to electroproduction we again encounter normalization difficulties.

High-energy cross sections fore−e+→μ−μ+andqq¯in the Salam-Ward-Weinberg model

Explicit formulas are given for the high-energy total cross section and angular distribution (asymmetry) in $\overline{e}e\ensuremath{\rightarrow}\overline{\ensuremath{\mu}}\ensuremath{\mu}$, $\overline{q}q$ in models of the Salam-Ward and Weinberg type in the three approximation. As expected, the pure weak terms cannot be neglected as the center-of-momentum energy approaches the mass of the neutral heavy vector boson $Z$.

Inelastic screening and total nuclear cross sections

We calculate high-energy neutron-lead total cross sections in the range of laboratory momenta from 5 to 400 GeV/c including inelastic-screening effects to all orders. Lowest-order screening corrections are seen to be dominant. The results are compared with experiment.

Intermolecular potentials obtained from high-energy alkali scattering

Intermolecular potentials have been obtained from high-energy total cross sections for several alkali metal systems: CS + He, Ne, Ar, CH 3NO 2; K + CH 4, C(CH 3) 4, C 6H 6, c-C 6H 12, CH 3I, CCl 4, SF 6, N 2. For the CS-rare gas cases and K + N 2 only the repulsive part was determined. For the rest both attractive and repulsive parts were seen.

SU(4) × SU(4) analysis of high energy cross-sections and photoproduction

Formulas for high energy total cross-sections are obtained using the method of Cabibbo, Horwitz and Ne'eman to compute the vector and tensor Regge exchange couplings in the framework of SU(4) × Su(4). Inequalities and identities between cross-sections found for SU(3) × SU(3) remain valid and some new relations are obtained which involve charmed particles. A fit to high energy total cross-sections is constructed and, with the assumption of vector dominance, this fit is consistent with photoproduction data above threshold.

High-energy total cross sections on nuclei

We discuss some features of the description of hadron-nucleus total and inelastic cross sections at present and foreseeable energies within the framework of Reggeon calculus. In the first (theoretical) part we discuss the Amati-Stanghellini-Fubini cancellation, emphasizing the analytic features involved, especially the consistency with unitarity in the Reggeon-particle channel. In the second (phenomenological) part we show that the observed triple-Pomeron coupling is so small that effects of Reggeon interactions can probably be ignored both at Fermilab energies and for observations of extensive air showers. It follows that the Glauber formula should describe all current experiments with only small corrections for inelastic intermediate states. (AIP)

Does the Pomeron have vacuum quantum numbers?

From general arguments, the imaginary part of every elastic scattering amplitude at sufficiently large impact parameter is governed by the two-pion exchange cut in the $t$ channel. Consequently, the large-impact-parameter tail of the Pomeron is not an SU(3) singlet. We calculate the contribution of the tail (typically about ${\ensuremath{\sigma}}_{\mathrm{tot}}$) approximately, and thereby predict observable differences between high-energy total cross sections for $\ensuremath{\pi}p$ and $Kp$, and between $pp$, $\ensuremath{\Lambda}p$, $\ensuremath{\Sigma}p$, and $\ensuremath{\Xi}p$. We estimate the asymptotic difference between $\ensuremath{\pi}p$ and $pp$ cross sections. We also obtain nonzero estimates for the diffractive helicity-flip component of elastic scattering and for diffractive contributions to processes such as $\ensuremath{\pi}p\ensuremath{\rightarrow}{A}_{2}p$ and $Kp\ensuremath{\rightarrow}{K}^{*}(890)p$. We predict cross sections for ${A}_{2}$ and ${K}^{*}$ at Fermilab, and elastic polarizations, e.g., in $pp\ensuremath{\rightarrow}pp$ and $\ensuremath{\Lambda}p\ensuremath{\rightarrow}\ensuremath{\Lambda}p$, at asymptotic energies.