We reanalyze the W-boson loop in the amplitude of the Higgs boson decay into two photons to show the absence of decoupling in the limit of massless W bosons, m(W) -> 0. The Higgs coupling to longitudinal polarizations survives in this limit and generates a nonvanishing contribution in the H -> gamma gamma decay. This shows that the recent claim of decoupling by R. Gastmans, S. L. Wu, and T. T. Wu is incorrect, and the old calculations for the two-photon decay well known in the literature are valid.

theoretical physicist of world renown and correspondent member of the Russian Academy of Sciences, died at the age of 70. Born in Moscow, Kaidalov was educated in nuclear and elementary particle physics at the Engineering Physics Institute (MEPhI), from which he graduated in 1963. He completed his diploma thesis under the guidance of I Ya Pomeranchuk, who then headed the Theoretical Department at the Institute of Theoretical and Experimental Physics (ITEP), which Kaidalov joined soon after his graduation from MEPhI and to which he remained devoted to the end of his days. Having started his academic career as a junior researcher, he became the head of a theoretical laboratory. He defended his PhD thesis in 1968 and received the degree of a Doctor of Sciences in 1979. In 2003, Kaidalov was elected a correspondent member of the RussianAcademy of Sciences. Even at the onset of his carrier, the young researcher showed a keen scientific intuition, the ability to see the most essential features of physical phenomena and to offer a suitable theoretical interpretation. At that time, experiments at the ITEP and Protvino accelerators (and later at ISR at CERN) started yielding a plethora of information about high-energy hadron interactions. With basic studies in highenergy physics just gaining momentum at that time, the method of complex angular momenta based on the analyticity and unitarity of the scattering amplitude (the Reggeon theory) marked a real breakthrough in this domain. Kaidalov pioneered the application of this approach to a systematic description of the hadron±hadron interaction dynamics at high energies. His first work investigated the role of moving Regge cuts, a relevant problem at that time. Kaidalov predicted a number of striking qualitative effects arising from the contribution of cuts to the cross sections of two-particle processes, which were later confirmed in experiment. A thorough analysis of diffraction dissociation processes enabled Kaidalov to establish the lower bound for twoPomeron cuts, thereby removing any doubt as to the necessity of taking them into account. His analysis of inelastic diffraction processes was of paramount importance for understanding the structure of the Reggeon field theory. He was the first to derive the triple-Pomeron interaction constant that characterizes the contribution of more complicated (`enhanced') diagrams of the Reggeon field theory. The method of Reggeon dispersion sum rules proposed by Kaidalov was used to predict the exotic baryon resonance with spin and isospin 5/2. Kaidalov made an invaluable contribution to the theory of multiple high-energy processes. When most theorists regarded the first experimental data as a mere haphazard collection of plots and figures, Kaidalov identified the main experimental findings as the effects of multiperipheral dynamics and t-channel quantum numbers. He and his coworkers proposed a model of Reggeized one-pion exchange that permitted systematizing and quantitizing a large number of inclusive and exclusive reactions in a broad energy range. The advent of quantum chromodynamics required the general phenomenological results of the Reggeon theory to be reformulated in terms of quarks and gluons. Kaidalov developed a new approach to the description of multiple processes at high energies (known as the quark±gluon string model) based on fundamental features of the Reggeon method, the topological 1=N expansion of QCD amplitudes, and current views of the confinement mechanism. This model was used to clarify the relationship between different Regge trajectories, to theoretically estimate cross sections of multiple hadron processes, to quantitatively describe a multitude of inclusive processes, and to predict the masses and widths of new hadron resonances, including exotic ones. Moreover, the Uspekhi Fizicheskikh Nauk 181 (3) 341 ± 342 (2011) DOI: 10.3367/UFNr.0181.201103j.0341 Translated by Yu VMorozov PERSONALIA PACS number: 01.60.+q

We try to identify symmetry associated with the topological current of gluon field Kμ. We argue that in the case of supersymmetric Yang-Mills theory the matrix elements of ∂μKμ can be evaluated by varying the effective action with respect to the bare coupling constant. The triangle graph does not obey this relation and represent an anomaly. In the case of pure Yang-Mills fields the notion of conserved chirality is introduced for a special background in one-loop order. In particular the conservation of the chirality implies again the “naive” vanishing of the triangle graph.

Supersymmetric gauge theories with Higgs mechanism are considered. After all heavy fields are integrated out we are left with the instanton-induced effective action for light fields. It is demonstrated that the one-loop instanton result is not modified by higher order perturbative corrections. The peculiarity of the case considered is that the background scalar fields do not possess definite chirality, and the bosonic and fermionic modes are not degenerate for this reason.

We consider a gauge antisymmetric tensor field (which is equivalent to a massless scalar field on-mass-shell). We demonstrate that the total chiral current which accounts for the chirality of the vector ghost fields is not anomalous. We also dwell on the relation between the number of zero modes of the antisymmetric tensor field and the anomaly in the chiral current of the vector field.

The notion of chirality for an electromagnetic field which is conserved in interactions with gravitons is formulated. The corresponding chiral current is the one-particle-state analouge of the Pauli-Lubansky vector. The anomaly of this current in an external gravitational field is found. The results obtained are used for the calculation of the electromagnetic radiative correction to the fermionic chiral anomaly in a gravitational field.

A method for calculating the exact ..beta..-function (in all orders in the coupling constant), proposed earlier in supersymmetric electrodynamics, is generalized. The starting point is the observation that the low-energy effective action is exhausted by one loop, provided that the theory is supersymmetrically regularized both in the ultraviolet and in the infrared region in four dimensions. For the ultraviolet regularization the Pauli-Villars method is used, while for the infrared regularization two variants are considered. The first: quantization in a box of finite volume L/sup 3/: is universally applicable to any gauge theory. The second variant is based on an effective Higgs mechanism for generation of mass, and requires the presence of certain matter superfields in the Lagrangian. For the second method a necessary condition is the existence of flat directions: so-called valleys along which the energy of the vacuum vanishes. We quantize the field near a nonzero value of the scalar field from the bottom of the valley. After calculation of the one-loop effective action both variants give for the ..beta..-function the same exact expression which, in addition, coincides with our previous result extracted from instanton calculus. A few remarks on the problem of anomalies in supersymmetric gauge theories aremore » presented.« less

We get an exact relation for the β-function in SQED.

In the framework of supersymmetric theories we discuss correlators of the type , where W is the superfield strength and S is the chiral matter field in a theory with one flavor. As a consequence of the supersymmetry these correlators do not depend on the coordinates and are equal to zero in perturbation theory. We show that even in the limit x ..-->.. 0 not only instantons of size rhoapprox.x give a contribution, as was known before, but also instantons of the characteristic size rhoapprox.v/sup -1/, where v is the vacuum expectation value of the scalar field. We discuss theories in which v>>..lambda.. (..lambda.. is the parameter which determines the effective coupling constant). In this case both contributions can be taken into account consistently. In particular, we show that in terms of a new variable, which it is natural to call the supersymmetric generalization of the instanton size, the answer for the correlator can be expressed in terms of the contribution of instantons of size zero. The factorization property of the correlators and the fact that they are constant in space are obvious in this case.

Within the background field formalism we discuss vacuum loops in supersymmetric gauge theories. A direct connection is revealed between the absence (or presence) of high-order contributions and infrared regularization. A simple explanation is given why the instanton amplitude is exhausted by one loop whilst in the standard supergraph technique the effective action contains terms of all orders in the coupling constant. We present an exact relation between the Gell-Mann-Low function and the anomalous dimensions of matter superfields stemming from instanton calculus.

The exact ..beta.. function is derived in supersymmetric electrodynamics. The relationship between the second-order and higher-order coefficients and the infrared regularization is analyzed.