Singlet axial-vector coupling constant of the nucleon in QCD without instantons

We have analyzed axial-vector current-current correlation functions between one-nucleon states to calculate the singlet axial-vector coupling constant of the nucleon. The octet-octet and the octet-singlet current correlators, investigated in this work, do not require any use of instanton effects. The QCD and hadronic parameters used for the evaluation of correlators have been varied by (10 - 20)%. The value of the singlet axial-vector coupling constant of the nucleon obtained from this analysis is consistent with its current determination from experiments and QCD theory.Comment: A slightly modified version to be published in Physics Letters B; 14 pages with 6 figures and 1 tabl

Eta-nucleon and eta-prime-nucleon coupling constants in QCD and the role of gluons

Coupling constants of $\eta$ and $\eta^{\prime}$ mesons with nucleons have been calculated using the method of QCD sum rules. Starting from vacuum-to-meson correlation function of interpolating fields of two nucleons, its matrix element with respect to nucleon spinors has been considered. Coupling constants at the physical points have been estimated from extrapolation of results obtained at two other points. Anomalous glue has been found to give substantial contribution to the coupling constants and also accounts for a significant OZI-rule violation.Comment: 6 pages, 3 figures and 2 table

Eta-nucleon coupling constant in QCD with SU(3) symmetry breaking

We study the $\eta$NN coupling constant using the method of QCD sum rules starting from the vacuum-to-eta correlation function of the interpolating fields of two nucleons. The matrix element of this correlation has been taken with respect to nucleon spinors to avoid unwanted pole contribution. The SU(3)-flavor symmetry breaking effects have been accounted for via the $\eta$-mass, s-quark mass and eta decay constant to leading order. Out of the four sum rules obtained by taking the ratios of the two sum rules in conjunction with the two sum rules in nucleon mass, three are found to give mutually consistent results. We find the SU(3) breaking effects significant, as large as 50% of the SU(3) symmetric part.Comment: 13 pages, 12 figure

Axial and pseudoscalar current correlators and their couplings to eta and etaprime mesons

Correlators of singlet and octet axial currents, as well as anomaly and pseudoscalar densities have been studied using QCD sum rules. Several of these sum rules are used to determine the couplings f^8_eta, f^0_eta, f^8_etaprime and f^0_etaprime. We find mutually consistent values which are also in agreement with phenomenological values obtained from data on various decay and production rates. While most of the sum rules studied by us are independent of the contributions of direct instantons and screening correction, the singlet-singlet current correlator and the anomaly-anomaly correlator improve by their inclusion.Comment: 31 pages, 11 figure

History of Indian asceticism in pre-Buddhistic times.

This study is concerned with the origins and the development of Indian asceticism before the time of the Buddha. In: the first chapter we have tried to define the concept of asceticism and fix its typology. We have included the practices of Upasana and Yoga in asceticism. The second chapter is devoted to the study of asceticism in the Indus Civilisation and in the Samhitas. We have taken each Samhita separately and studied tapas. vata, svama and other terms which may have a bearing on the subject in the context of the cultural material as revealed in that particular samhita. We have studied also such personalities as the muni, yati and vatya. In dealing with the vatya We have concentrated only on the book XV of the Av, leaving aside the materials found in the Brahmanas for the second chapter. This has involved a general criticism of the views of the scholars who have worked on the subject, and a re-appraisal of the AV.XV. which has led to quite different results. In the third chapter we have again dealt with the terms seen in the Brahmanas. Along with this we have studied the sacrificial practises involving austerities such as fasting, dietary regulations, keeping vigil and so forth. These regulations are not only observed separately but axe gathered together in the Diksa ritual which has been treated exhaustively. We have suggested that the diksa was the arche-type of later austerities. In this period new ascetic personalities such as the Carakas and the Vaikhanasas appeared. The Vatyas-have, been again dealt with exhaustively and have been found to be an organised community containing shaman-like priests. It has been ten-tatively suggested that they might be identified with the people of the copper hoards of the Gangetic valley. In the fourth chapter we have treated the material found in the Aranyakas and the Upanisads together. We find new developments in the ascetic mode of living. Asceticism comes predominantly to mean self-discipline, beside the earlier conception of asceticism as self-mortification. Though the ascetic mode of living was accepted in later Vedic society, had not been integrated as a social institution in the framework of the aszama system. The practices of Upasana and Yoga are seen to be well-developed by the end of this period. The fifth chapter gives a short summary of the views put forward in the earlier chapters and a short comparison of the conclusions arrived at: with the Jaina and the Buddhist evidence

Axial and pseudoscalar current correlators and their couplings to eta and eta(') mesons

Correlators of singlet and octet axial currents, as well as anomaly and pseudoscalar densities have been studied using QCD sum rules. Several of these sum rules are used to determine the couplings f(eta)(8),f(eta)(0), f(eta)('8) and f(eta)('0). We find mutually consistent values which are also in agreement with phenomenological values obtained from data on various decay and production rates. While most of the sum rules studied by us are independent of the contributions of direct instantons and screening correction, the singlet-singlet current correlator and the anomaly-anomaly correlator improve by their inclusion

Electromagnetic quark mass difference and dynamical symmetry breaking

By considering the effect of QCD feedback on electromagnetic self-energy, we analyze the up- and down-quark mass difference taken as the difference of electromagnetic self-energies, in a dynamically broken chiral-invariant QCD. We find that this does not remove the wrong sign of (mu-md) for any reasonable value of momenta