**
MAIN RESEARCH RESULTS (no update after 2020)**

**In: Cosmology Supersymmetry and Supergravity Strings and Superstrings
Branes and M-Theory Conformal Field theory
Non-linear Sigma-models**

*MAIN ORIGINAL RESULTS IN SCIENTIFIC RESEARCH :*

- First construction of the so-called * N=2 supersymmetric tensor multiplets* in 4D, N=2
projective superspace, first derivation of the manifestly * N=4 supersymmetric Feynman rules *
in 2D, and their use for a proof of the * UV-finiteness * of 2D, N=4 supersymmetric non-linear sigma-models:
S.V. Ketov, *New Self-interaction for N = 2 Multiplets in 4D, and Ultraviolet Finiteness of Two-dimensional
2D, N = 4 Sigma-models,* Intern. Seminar in Group Theory Methods in Physics, Urmala, USSR, 1985;
Nauka, Moscow, Vol. 1, p. 87;

- First explicit construction of all IRREDUCIBLE SU(2)-extended scalar
superfields in 4D, N=2 Superspace: S.V. Ketov, *N=2 Extended Supersymmetry and
Irreducible SU(2) Extended Superfields, * Fortschr. Phys. 36, 361, 1988;

- First explicit calculation of the 3-LOOP renormalization group beta-function and
Zamolodchikov effective action in a generic 2D non-linear sigma-model WITH TORSION:
S.V. Ketov, A.A. Deriglazov and Ya.S. Prager, * Three-loop Beta-function of Two-dimensional
Non-linear Sigma-model with Wess-Zumino-Witten Term, * Nucl. Phys. B332, 447, 1990;

- First explicit construction of the SELF-DUAL supersymmetric Yang-Mills and supergravity
theories in N=1, 2 and 4 Superspace: S.V. Ketov, S.J. Gates Jr., and N. Hishino, *Self-Dual Supersymmetry
and Supergravity, * Nucl. Phys. B393, 149, 1993; *over 80 citations*

- First explicit construction of the PATH INTEGRAL MEASURE and the SPECTRAL FLOW OPERATOR
in N=2 string theory: S.V. Ketov and O. Lechtenfeld, *The string measure and spectral flow of critical N=2 strings,
* Phys. Lett. B353, 463, 1995;

- First explicit construction of the EXCEPTIONAL NON-LINEAR N=7 and N=8 SUPERCONFORMAL ALGEBRAS in terms
of free fields, based on their relation to octonions and 7-sphere, M. Gunaydin and S.V.Ketov, * Seven-Sphere, and the
Exceptional N=7 and N=8 Superconformal Algebras, * Nucl. Phys. B467, 215, 1996;

- First manifestly N=2 supersymmetric calculation of the ONE-LOOP HYPERMULTIPLET low-energy effective action:
E.A Ivanov, S.V. Ketov and B.M. Zupnik, * Induced Hypermultiplet Interactions in N=2 Gauge Theories, *
Nucl. Phys. B509, 53, 1998; *over 65 citations*

- First construction of the N=1 and N=2 SUPERSYMMETRIC Abelian and non-Abelian BORN-INFELD actions in
superspace in 4D and 6D: S.V. Ketov, * Manifestly N=2 Supersymmetric Born-Infeld Action, * Mod.Phys. Lett. A14,
501, 1999; S.V. Ketov,* Born-Infeld-Goldstone Superfield Actions for Gauge-fixed D-5- and D-3-branes in 6d, *
Nucl. Phys. B553, 250, 1999; (known as the "Ketov equation" for the N=2 Born-Infeld theory in the literature)
*over 55 citations*

- First explicit SUMMATION of D-INSTANTONS (from D-branes wrapped over Calabi-Yau cycles): S.V. Ketov,
* Summing up D-instantons, * Nucl. Phys. B649, 365, 2003;

- First explicit construction of the 4D, N=1/2 supersymmetric non-linear sigma models in NON-ANTI-COMMUTATIVE
superspace, with the physical effects of smearing and splitting: T. Hatanaka, S.V. Ketov, Y. Kobayashi and S. Sasaki,
* N=1/2 supersymmetric 4-dimensional non-linear sigma-models from non-anti-commutative superspace,* Nucl. Phys.
B726, 481, 2005;

- First construction of F(R) SUPERGRAVITY in superspace and their application to INFLATION: S. J. Gates Jr. and S.V. Ketov, *Superstring-induced supergravity as the universal source of inflation and quintessence, * Phys. Lett. B674, 2753, 2010; also S.V. Ketov and A.A. Starobinsky, * Embedding (R+R^2) inflation into supergravity,* Phys. Rev. D063512, 2011; *over 85 citations*

- First realization of INFLATION in supergravity with a SINGLE matter superfield:
S.V. Ketov and T. Terada, * Inflation in supergravity with a single chiral superfield,* Phys. Lett. B736,
272, 2014

- First realization of INFLATION with spontaneous SUSY breaking and a dS vacuum after inflation, in supergravity with inflaton in a massive vector multiplet:
Y. Aldabergenov and S.V. Ketov, * SUSY breaking after inflation in supergravity with inflaton in a massive vector
supermultiplet,* Phys. Lett. B761, 115, 2016