• V Gupta

Articles written in Pramana – Journal of Physics

• A model for the multiplicity distribution in pp-collisions from 5 to 300 GeV/c

The multiplicity distribution of charged particles in pp-collisions in the range 5–300 GeV/c is explained on the basis of a dynamical model which leads to a specific mixture of Poisson distributions.

• Correlations in pp-collisions and two-component models

Some general consequences of charge conservation inclusive sum rules for the correlation integralsfkandf0k are given. It is also pointed out that the energy dependence offkorf0k is 〈nk fork≤7 for pp-collisions and that the data suggest all thefk andf0k’s are non-zero. Further, two-component models for the charge multiplicity distribution consistent with charge conservation, are considered and compared with the data for pp-collisions.

• Neutral-charged particle correlations in proton-proton collisions in the framework of a two-component model

The data on$$\bar N_0 \left( {n\_} \right)$$, the average number of neutrals as a function ofn, the number of negatively charged particles produced, is fitted at 69, 205 and 303 GeV/c. The two-component model used for the charged multiplicity distributionPn, is one which envisages two distinct types of collisions and is the simplest such model consistent with charge conservation. We find that the data on$$\bar N_0 \left( {n\_} \right)$$ can be fitted reasonably well. Further, our results, based on this model forPn, suggest that at 50 GeV/c,$$\bar N_0 \left( {n\_} \right)$$ should increase linearly withnand that neutral-negative correlations should be present in the central component.

• Charge transfer inpp collisions according to a mixed two component model

The charge transfer from one hemisphere to the other, observed inpp-collisions is explained on the basis of a ‘mixed two component’ model, which has been proposed previously to account for the multiplicity distribution of charged particles. Results of the calculations, based on the model, for various measurable quantities relating to charge transfer are compared with the available experimental data.

• Sum rules for the baryon20, baryon20′ and meson 16-plet coupling constants in broken SU (4) and SU (3) symmetry

Sum rules for the coupling constants for D (20), B (20′) and P (16) are given taking into account first order breaking of SU (4) and SU (3) symmetries. The D (20) and B (20′) contain the usual 3/2+ baryon decuplet and 1/2+ baryon octet of SU (3), while the P (16) contains the usual pseudoscalar octet of pions, etc. These sum rules generalize the decuplet → octet + octet sum rules of broken SU (3 to a broken SU (4) symmetry scheme, in particular the charm SU (4) for hadrons. It is pointed out that, of the many sum rules, it may be possible to check some of them experimentally (see Section 5) and thus provide a test for an underlying SU (4 symmetry for strong interactions.

• Non-leptonic weak decays of charmed baryons

It is shown that the ΔChS decays of a baryon sextuplet, triplet and singlet of SU (3), into meson and baryon, can provide simple tests of the iscspin and SU (3) transformation properties of the ΔChS non-leptonic interaction in the Glashow Iliopoulos-Maiani scheme.

• Some consequences of neutral current systematics

Two kinds of general consequences of the ΔS=0 weak hadron neutral current independent of a gauge model are presented. Firstly are results which depend on the quark parton model. These involve bounds among neutrino inclusive cross-section and a bound onQ(Z, N) in terms of these inclusive cross-sections. Secondly are results which are independent of the quark-parton model and depend only on the SU(3) structure of the most general ΔS=0 neutral current. These tests of isopin and speciallyU-spin properties of the current are given forv+Nv+hadron+anything,v+Nv+baryon+meson ande+e→baryon+anti-baryon. In addition some conjectures are made with regard to the semi-inclusive neutrino-reactions using the quark parton model.

• Quantum chromodynamics corrections to polarised deep-inelastic electron-nucleon scattering

Quantum chromodynamics corrections to orderαs (the running coupling constant), using the quark-parton approach are calculated for the spin-dependent structure functions in deep-inelastic polarised electron-nucleon scattering. Consequences of these corrections for the Bjorken sum rule and the asymmetry in the case of longitudinally polarised (with respect to the beam) nucleons is discussed which could provide possible tests of quantum chromodynamics. Comparison of our results with the moments of the flavour non-singlet contribution to the structure functions obtained using operator product expansion is also given.

• Quantum chromodynamics corrections to polarised deep-inelastic electron-nucleon scattering

• Gauge invariance and renormalization schemes in quantum chromodynamics

A general analysis of the Slavnov-Taylor identity connecting the triple gluon and ghost-ghost-gluon vertices and its consequences for two momentum subtraction (symmetric and asymmetric) renormalization schemes are given. It is shown that in the asymmetric scheme proposed in this paper the relation $$Z_3 Z_{1^{ - 1} } = \tilde Z_8 \tilde Z_{1^{ - 1} }$$follows directly from the identity for a simple and natural definition of the renormalization constants. Explicit one-loop expressions for the renormalization constants $$\left( {Z_1 ,Z_3 ,\tilde Z_1 \tilde Z_3 } \right)$$in an arbitrary covariant gauge, including quark masses are given in support of the general analysis.

• Quantum chromodynamics predictions in renormalization scheme invariant perturbation theory

It has recently been shown that any physical quantity ℛ, in perturbation theory, can be obtained as a function of only the renormalization scheme (rs) invariants,ρ0,ρ1,ρ2, … Physical predictions, to any given order, are renormalization scheme independent in this approach. Quantum chromodynamics (qcd) predictions to second order, within thisrs-invariant perturbation theory, are given here for several processes. These lead to some novel relations between experimentally measurable quantities, which do not involve the unknownqcd scale parameter Λ. They can therefore be directly confronted with experiments and this has been done wherever possible. It is suggested that these relations can be used to probe the neglected higher order corrections.

• Some consequences of global horizontal symmetry

It is pointed out that the present SU(3)c×SU(2)L×U(1) gauge interactions with three families have a global horizontal symmetry (denoted hereby SU(3)H) which is broken only by the weak charged hadron currentJh. Also, with (u, c), (d, s), (ve, {ie437-1}) and (e,μ) as doublets of SU(2)H (subgroup of SU(3)H),Jh has simple transformation properties under this subgroup. Amplitude relations, using SU(2)H symmetry, for hadronic leptonic and semileptonic decays are given.

• Supersymmetric preon models with three-fermion generations

A class of supersymmetric preon models is considered in which the hypercolour groupGHC and the unbroken flavour groupGf anomalies are zero without needing spectators. It is shown that forGHC=SU(2) and SU(3) quarks and leptons as composites can be obtained satisfying ’t Hooft’s anomaly matching conditions. For the case ofGHC=SU(3),Gf can accommodate a horizontal symmetry group to describe just three generations.

• An analysis of the mass formulae forS- andP-wave mesons

Mass regularities forS- andP-wave mesons and relations between their masses are discussed. A detailed analysis is given forS-wave mesons which extends the investigations onP-wave mesons reported earlier. Masses for theS- andP-states of all interesting$$q\bar q$$-systems (including toponium states) are predicted. Partial understanding of the mass formulae is obtained within a general potential model approach. Scaling arguments are presented which support the empirical scaling behaviour found for the expectation values determining the spin-splittings in the potential picture.

• Interpretation of the recent Kolar events

We give plausible interpretations of the unusual events seen in the proton decay detector at Kolar Gold Fields indicating the existence of a massive (≳2GeV) long lived (10−8−10−9s) particle. We show that it is possible to accommodate the particle in the standard model as a fourth generation neutrino, or inE6 grand unified theory as a neutral fermion occurring in27 representation or in supersymmetric theory as a scalar neutrino. However, there is a difficulty in explaining the large production rate for the particle.

• Current algebra results for theB - D systems

Using the equal time commutation relations for the components of the vector and axialvector currents and keeping single particle states we obtain relations for the weak form factors for theB - D systems. In the heavy quark effective theory (HQET) limit these relations determine the Isgur-Wise function.

• Pramana – Journal of Physics

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Volume 93 | Issue 5
November 2019

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