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A. Dymarsky

Publications and source records attributed to A. Dymarsky.

8 recordsLinked to original sources
arXiv2015

Can Froissart Bound Explain Hadron Cross-Sections at High Energies?

Experimentally observed slow growth of hadron cross-sections at high energies is a very intriguing but poorly understood property of QCD. It is tempting to explain the slow growth by saturation of Froissart bound or another similar universal mechanism. We reconsider derivation of Froissart bound in QCD in chiral limit and argue it can not justify experimentally observed behavior. Although the conventional Froissart-Martin bound should impose non-trivial constraint on the growth of hadron cross-sections, because of the small value of pion masses it will become restrictive only at currently unaccessible center-of-mass energies exceeding $10^5-10^6$ GeV.

hep-ph↗
arXiv2008

Gravity Multiplet on KS and BB Backgrounds

In this paper we study the spectra of glueballs on the Klebanov-Strassler background and its extension to the baryonic branch. We numerically calculate the mass spectrum of glueballs from the spin 2 ``gravity'' multiplet, which contains the traceless part of the stress-energy tensor and the transverse part of the U(1) R-current. The mass spectra of the corresponding fluctuations in supergravity coincide due to supersymmetry, which is manifest in the effective five-dimensional theory through a Supersymmetric Quantum Mechanics transformation. We show that the glueball spectra grow as m^2 ~ Un^2 for large values of the baryonic branch parameter U.

hep-th↗
arXiv2006

Calibrated Surfaces and Supersymmetric Wilson Loops

We study the dual gravity description of supersymmetric Wilson loops whose expectation value is unity. They are described by calibrated surfaces that end on the boundary of anti de-Sitter space and are pseudo-holomorphic with respect to an almost complex structure on an eight-dimensional slice of AdS_5 x S^5. The regularized area of these surfaces vanishes, in agreement with field theory non-renormalization theorems for the corresponding operators.

hep-th↗
arXiv2005

Perturbative Gauge Theory and Closed String Tachyons

We find an interesting connection between perturbative large N gauge theory and closed superstrings. The gauge theory in question is found on N D3-branes placed at the tip of the cone R^6/Gamma. In our previous work we showed that, when the orbifold group Gamma breaks all supersymmetry, then typically the gauge theory is not conformal because of double-trace couplings whose one-loop beta functions do not possess real zeros. In this paper we observe a precise correspondence between the instabilities caused by the flow of these double-trace couplings and the presence of tachyons in the twisted sectors of type IIB theory on orbifolds R^{3,1}x R^6/Gamma. For each twisted sectors that does not contain tachyons, we show that the corresponding double-trace coupling flows to a fixed point and does not cause an instability. However, whenever a twisted sector is tachyonic, we find that the corresponding one-loop beta function does not have a real zero, hence an instability is likely to exist in the gauge theory. We demonstrate explicitly the one-to-one correspondence between the regions of stability/instability in the space of charges under Gamma that arise in the perturbative gauge theory and in the free string theory. Possible implications of this remarkably simple gauge/string correspondence are discussed.

hep-th↗
arXiv2005

Perturbative Search for Fixed Lines in Large N Gauge Theories

The logarithmic running of marginal double-trace operators is a general feature of 4-d field theories containing scalar fields in the adjoint or bifundamental representation. Such operators provide leading contributions in the large N limit; therefore, the leading terms in their beta functions must vanish for a theory to be large N conformal. We calculate the one-loop beta functions in orbifolds of the N=4 SYM theory by a discrete subgroup Gamma of the SU(4) R-symmetry, which are dual to string theory on AdS_5 x S^5/Gamma. We present a general strategy for determining whether there is a fixed line passing through the origin of the coupling constant space. Then we study in detail some classes of non-supersymmetric orbifold theories, and emphasize the importance of decoupling the U(1) factors. Among our examples, which include orbifolds acting freely on the S^5, we do not find any large N non-supersymmetric theories with fixed lines passing through the origin. Connection of these results with closed string tachyon condensation in AdS_5 x S^5/Gamma is discussed.

hep-th↗
arXiv2002

String theory derivation of RR couplings to D-branes

We derive the couplings of D-branes to the RR fields from the first principles, i.e. from the nonlinear sigma-model. We suggest a procedure to extract poles from string amplitudes, before the eventual formula for the couplings is obtained. Using the fact that the parts of amplitudes with poles are irrelevant for the effective action this procedure ultimately simplify the derivation since it allows us to omit these poles already from the very beginning. We also use the vertex for the RR fields in the (-3/2,-1/2) ghost picture as the useful tool for the calculation of such string amplitudes. We carry out the calculations in all orders of brane massless excitations and obtain the Myers-Chern-Simons action. Our goal is to present the calculations in full technical details and specify the approximation in which one obtains the action in question.

hep-th↗
arXiv2001

Noncommutative field theory in formalism of first quantization

We present a first-quantized formulation of the quadratic non-commutative field theory in the background of abelian (gauge) field. Even in this simple case the Hamiltonian of a propagating particle depends non-trivially on the momentum (since external fields depend on location of the Landau orbit) so that one can not integrate out momentum to obtain a local theory in the second order formalism. The cases of scalar and spinning particles are considered. A representation for exact propagators is found and the result is applied to description of the Schwinger-type processes (pair-production in homogenous external field).

hep-th↗