Deep Inelastic Region Research Articles

Quark-parton model with pair correlation

A relativistic quark-parton model is used to study the deep-inelastic lepton-hadron scattering phenomena. It is assumed that there is some correlation among the valence quarks, at least near the threshold of the deep-inelastic region. The assumption has been motivated by the observed threshold behavior of the structure functions of the nucleon. The inclusion of the pair correlation leads to an improved agreement between the quark-parton results and the experimental data. The question of the validity of the model has also been studied.

Absorption corrections in a mueller regge analysis of inclusive photo- and electroproduction

We discuss the photon fragmentation region of inclusive pion photo- and electroproduction in terms of a helicity dependent Mueller-Regge model, in which cut contributions are taken into accout. It is shown that the inadequacies of a pure Regge pole expansion can be corrected if certain types of Regge cut contributions are included. The transition from electro-production to the photo-production limit is shown to be non-smooth in the case of charged pions and we point out that normal triple-Regge mechanisms are unlikely to be important in the deep inelastic region.

Deep inelastic two-particle distributions in the two-component parton model

The two-component parton model is used for the description of inclusive two-particle distributions in the deep inelastic region. Simple predictions for the cross sections and correlation functions in electroproduction and in e +e − annihilation are presented.

J = 0 Singularity in Forward Virtual Compton Amplitude

In the approximation that R = σS/σT is a function only of the virtual photon mass squared q2, we write down the ν-variable dispersion relation for Ti(ν, q2). We investigate phenomenologically the contribution of J = 0 singularity to the FESR assuming that the Pomeron and the Regge poles (f0, A20) are expressed by scaling functions except for a region near the photoabsorption threshold. The argument indicates a residue of J = 0 singularity C(q2) ∝ [-q2/a2 - q2]αi(0) + [Born contribution]. Thus the residue of J = 0 singularity is not polynominal in q2 and C(0) is smoothly continued to the deep inelastic electroproduction region.

Nonuniformity of the Adler sum rule in the deep-inelastic region

Nonuniformity of the Adler sum rule in the deep-inelastic region

High-Energy Single-Arm Inelastice−pande−dScattering at 6 and 10°

Differential cross sections for electron scattering from hydrogen and deuterium in the deep-inelastic region show that the neutron cross section is significantly smaller than the proton cross section over a large part of the kinematic region studied. Although $\ensuremath{\nu}{{W}_{2}}^{d}$ differs in magnitude from $\ensuremath{\nu}{{W}_{2}}^{p}$, it exhibits a similar scaling behavior.

Tests of the Three-Triplet Models in the Deep-Inelastic Region

Light-cone algebra is written for the currents transforming like (1,8), (8,1), and (8,8) representations of SU(3)\ensuremath{''} \ensuremath{\bigotimes} SU(3)\ensuremath{'}, and is used to obtain the predictions of the Han-Nambu model and the Cabibbo-Maiani-Preparata model for the Bjorken form factors. Comparison is made with the usual light-cone current-algebra results.

Hadronic Final States of Deep-Inelastic Processes in Simple Quark-Parton Models

Bjorken and Feynman have suggested a quark-parton-model approach to predicting the final-state hadron spectra in deep-inelastic processes. Since the final-state interaction in their approach is characterized by short-range correlations in rapidity, it is natural to ask whether parton models with final-state interactions based on conventional multiperipheral dynamics might provide realizations of their picture. This is found to be untrue. We argue by studying perturbation-theory models (${\ensuremath{\varphi}}^{3}$ and cutoff vector-gluon ladder models) and by formulating a rather general intuitive space-time argument that in naive parton models of this type one cannot avoid the appearance of isolated-quark quantum numbers in the final state. In the $\ensuremath{\lambda}{\ensuremath{\varphi}}^{3}$ models the final-state interaction always vanishes in the deep-inelastic region (as well as in the high-energy annihilation region) regardless of the size of $\ensuremath{\lambda}$. In the vector-gluon model, the final-state interaction does not vanish asymptotically, but the struck quark parton cannot exchange its charge with the target fragments. The character of parton dynamics necessary to realize the Bjorken-Feynman picture is discussed.

Electroproduction on nucleons of a muon pair as a test of the bilocal algebra

We present a full calculation of the cross section for eN→e+( μ + μ −)+ hadrons in the deep inelastic region using light-cone algebra.

Unified Model of Current-Hadronic Interactions

A model for current-hadronic interactions is constructed which satisfies (a) Mandelstam analyticity, (b) crossing symmetry, (c) scale invariance in the deep-inelastic region, (d) Regge behavior in all channels, (e) resonance poles in the unphysical sheet, (f) generalized vector-meson dominance, and (g) SU(3) structure of the currents. There is a fixed pole in the charged photon-proton scattering amplitude, so that the Dashen-Fubini-Gell-Mann and Adler sum rules are satisfied. Good fits are obtained for Compton scattering at energies above 5 GeV for all experimentally available values of ---${q}^{2}$, and also for all deep-inelastic electroproduction data. By fixing all parameters with these fits, and with preliminary data obtained from deep-inelastic experiments on production by neutrinos, we are able to make parameter-free predictions of ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\omega}}^{0}$ photoproduction and electroproduction, which agree well with the data.

New Approach to Relations Between Deep-Inelastic Structure Functions

It is argued that symmetry properties available from experiments outside deep-inelastic physics can provide guidance for understanding the structure functions in the deep-inelastic region. In particular, it is suggested that the component of the current that transforms like the "$\ensuremath{\varphi}$" is more weakly coupled to nonstrange hadrons than the components which transform like the "$\ensuremath{\rho}$" or "$\ensuremath{\omega}$" This leads to a stringent upper bound for the sum of the electromagnetic structure functions, ${F}_{2}^{\ensuremath{\gamma}p}+{F}_{2}^{\ensuremath{\gamma}n}$, which can be tested by experiments.

Internal symmetries and an analysis of bilocal operators and partons with three-triplet currents

Three-triplet quark currents for the weak and electromagnetic interactions are examined in the context of different internal symmetry groups. Parton models constructed out of these currents are then applied to investigate the usual deep inelastic region of eN→μN and\(\left( {\nu ,{\mathbf{ }}\bar \nu } \right)\mathcal{N} \to \mu X\). The relevant bilocal current algebra on the light-cone is examined and correspondence with parton models demonstrated. To test these hypotheses of internal symmetries and the full bilocal current algebra based on them, we study the semi-inclusive processes lH→l’(l+l−)X (l, l’ are leptons, l+, l− the lepton pair and H is any hadron target) in a generalized Bjorken limit. In particular, sum rules are derived to test the symmetries in the process eN→e(μ+μ−)X. The implications of these hypotheses on π0→2ψ, e+e−→ hadrons, e+e−→(p, n)X, and deep inelastic ψp→(μ+μ−)X are also discussed.

Testing gauge theories of weak interactions in the deep inelastic region

The analogs of the Adler sum rule and the Llewellyn-Smith relation for the Georgi-Glashow and Lee-Prentki-Zumino models for weak interactions, are derived. It is suggested that these could provide useful tests of the models.

Hardonic Final States of Deep-Inelastic Processes in Simple Quark-Parton Models

Bjorken and Feynman have suggested a quark-parton-model approach to predicting the final-state hadron spectra in deep-inelastic processes. Since the final-state interaction in their approach is characterized by short-range correlations in rapidity, it is natural to ask whether parton models with final-state interactions based on conventional multiperipheral dynamics might provide realizations of their picture. This is found to be untrue. We argue by studying perturbation-theory models (${\ensuremath{\varphi}}^{3}$ and cutoff vector-gluon ladder models) and by formulating a rather general intuitive space-time argument that in naive parton models of this type one cannot avoid the appearance of isolated-quark quantum numbers in the final state. In the $\ensuremath{\lambda}{\ensuremath{\varphi}}^{3}$ models the final-state interaction always vanishes in the deep-inelastic region (as well as in the high-energy annihilation region) regardless of the size of $\ensuremath{\lambda}$. In the vector-gluon model, the final-state interaction does not vanish asymptotically, but the struck quark parton cannot exchange its charge with the target fragments. The character of parton dynamics necessary to realize the Bjorken-Feynman picture is discussed.

SU(6) W on the light cone

Using a transformation recently introduced by Melosh, the consequences of SU(6) W for the electro- and neutrino-production structure functions in the deep-inelastic region are investigated.

The bilocal algebra and the parton model in vμ + p → μ + e + + e − + hadrons

We calculated the cross section for v μ + p → μ − + e + + e − + hadrons in the deep-inelastic region using the Fritzsch and Gell-Mann light-cone algebra. The connection with the parton model is made.

Applications of the quark parton model in one-particle inclusive leptonic-induced reactions

The quark parton model is applied to the deep-inelastic region of single-particle inclusive lepton-hadron processes. The current-fragmentation region is mainly discussed. Various conclusions concerning experimentally observable quantities such as single-particle distribution functions and average multiplicities are reached. Sum rules such as the Bjorken and Adler sum rules are generalized to this case. The average multiplicities of current-fragment pions in neutrino reactions are found to be independent of the target and of x. They are related to electroproduction multiplicities. A relationship is established between the x → 0 limit of the latter, and pion multiplicities in e +e − annihilation. Assuming SU(3) invariance, relations among π and K multiplicities are derived.

New duality results for the proton-neutron electroproduction structure function difference

It is shown that the s-channel resonance contributions build up the I t = 1 Compton amplitude in the deep inelastic region. This is done by using ω W-scaling to relate the low energy photo- and electropriduction data and theory to the SLAC-MIT proton-neutron structure function difference measurements.

SU(2) Mass Splitting in the Vector Mixing Model

The SU(2) mass .splitting and mixing of the pseudoscalar and vector mesons are investi­ gated in connection with SU (3) breaking, under the assumption that the divergent self-energies caused by the vector mixing ,p and ifJ/OJ,P(SJ yield the tadpole-like mass splitting. The calculated values of JI = 1 mass splitting and mixing are in good agreement with experiment. It is remarkable . that our model unlike the conventionaL tadpole model gives a consistent value of m%,-mi,., and that the decay rates ~~37! and w~2rr estimated by using the calcu­ lated transitiOI1 masses are consistent with experiment. The observed value of m%.,-mi, •. and the tendency m~.-m~.>O are reproduced by a large value· of the magnetic moment. § 1. Introduction · The signs and magnitudes of the JI = 1 mass splitting and illixmg have not yet been explained satisfactorily; 1l A tadpole mbdePl was proposed to explain qualitatively the JI = 1 and SU(3) mass splittings. A common mechanism of the octet dominance is represented simply in this model. The tadpole together with the low energy contribution resulting from a few low-lying intermediate states has given a qualitative explanation of the SU(2) mass splitting. Many attempts to evaluate the tadpole term compared with the low-energy term have been carried out. It has been pointed out by Harari 3l that the JI = 2 parts of the ·mass difference may allow an unsubtracted dispersion relation, while an unknown subtraction term which· may be interpreted as the tadpole is needed for the 4T==1 mass splitting. Successively, the idea of tadpole has been given a somewhat differentinterpretation by Okubo, 4l namely that Reggeized tadpole may dominate the high-energy contribution for the JI = 1 mass splitting. The recent estimation6l of the contribution :from the deep inelastic region, based upon the parton model, showed that the high energy contribution seems to be important for the JI = 1 mass difference, but not for the JI = 2 one. On the other hand, in the case of the JI=2 mass splitting like ~;.-m;, alld ms.+ms--2mso, convergent results with the correct order of magnitude are derived by using the electro­ magnetic form factors in the Born approximation or by evaluation of the Cotting­ ham' formula 6l usillg simple pole donitnance in a dispersion relation. From these observations, it is plausible that the tadpole term of the SU(2) mass splitting represents the high energy behaviour of hadrons induced by the electromagnetic interaction. In spite of the qualitative success, it is found difficult to explain quantitatively

Measurements of inclusive hadron momentum distributions in deep inelastic electroproduction

In the deep inelastic region of electron scattering the distribution of hadrons in the direction of the virtual photon has been investigated. At q 2 = 1.16 GeV 2 and W = 2.63 GeV coincidence measurements between the scattered electron and photon, π ± and K ± have been made. Momentum and missing mass distributions are presented. They are compared with other electroproduction measurements, with photoproduction, and with hadronic reactions.