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Makeenko Y.,Institute of Theoretical and Experimental Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Lüscher term, and discuss an application to meson scattering amplitudes in QCD. © 2011 American Physical Society.


Barabash A.S.,Institute of Theoretical and Experimental Physics
Physical Review C - Nuclear Physics | Year: 2010

All existing positive results on two-neutrino double-β decay in different nuclei were analyzed. Using the procedure recommended by the Particle Data Group, weighted average values for half-lives of Ca48, Ge76, Se82, Zr96, Mo100, Mo100-Ru100 (01+), Cd116, Te130, Nd150, Nd150-Sm150 (01+), and U238 were obtained. Existing geochemical data were analyzed, and recommended values for half-lives of Te128, Te130, and Ba130 are proposed. Given the measured half-life values, nuclear matrix elements were calculated. I recommend the use of these results as the most currently reliable values for the half-lives and nuclear matrix elements. © 2010 The American Physical Society.


Simonov Yu.A.,Institute of Theoretical and Experimental Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Wave functions and energy eigenvalues of the path integral Hamiltonian are studied in the Lorentz frame moving with velocity v. The instantaneous interaction produced by the Wilson loop is shown to be reduced by an overall factor 1-(vc)2. As a result, one obtains the boosted energy eigenvalues in the Lorentz covariant form E=P2+M02, where M0 is the c.m. energy, and this form is tested for two free particles and for the Coulomb and linear interaction. Using Lorentz-contracted wave functions of the bound states, one obtains the scaled-parton wave functions and valence quark distributions for large P. Matrix elements containing wave functions moving with different velocities strongly decrease with growing relative momentum; e.g., for the timelike form factors, one obtains Fh(Q0)∼(MhQ0)2nh with nh=1 and 2 for mesons and baryons, as in the "quark counting rule." © 2015 American Physical Society.


Barabash A.S.,Institute of Theoretical and Experimental Physics
Nuclear Physics A | Year: 2015

All existing positive results on two-neutrino double beta decay in different nuclei were analyzed. Using the procedure recommended by the Particle Data Group, weighted average values for half-lives of 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 100Mo-100Ru (01+), 116Cd, 130Te, 136Xe, 150Nd, 150Nd-150Sm (01+) and 238U were obtained. Existing geochemical data were analyzed and recommended values for half-lives of 128Te and 130Ba are proposed. Given the measured half-life values, nuclear matrix elements were calculated using latest (more reliable and precise) values for phase space factor. Finally, previous results (PRC 81 (2010) 035501) were updated and results for 136Xe were added. © 2015 Elsevier B.V.


Akhmedov E.T.,Institute of Theoretical and Experimental Physics
Journal of High Energy Physics | Year: 2012

We explicitly show that the one loop IR correction to the two-point function in de Sitter space scalar QFT does not reduce just to the mass renormalization. The proper interpretation of the loop corrections is via particle creation revealing itself through the generation of the quantum averages a + p ap, a pa -p and a + a + -p, which slowly change in time. We show that this observation in particular means that loop corrections to correla- tion functions in de Sitter space can not be obtained via analytical continuation of those calculated on the sphere. We find harmonics for which the particle number ha+ p api dominates over the anoma- lous expectation values apa-p and a + p a +-p. For these harmonics the Dyson-Schwinger equation reduces in the IR limit to the kinetic equation. We solve the latter equation, which allows us to sum up all loop leading IR contributions to the Whiteman function. We perform the calculation for the principle series real scalar fields both in expanding and contracting Poincare patches. © SISSA 2012.


Simonov Y.A.,Institute of Theoretical and Experimental Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The proper-time 4D path integral is used as a starting point to derive the new explicit parametric form of the quark-antiquark Green's function in gluonic and QED fields entering as a common Wilson loop. The subsequent vacuum averaging of the latter allows us to derive the instantaneous Hamiltonian. The explicit form and solutions are given in the case of the qq̄ mesons in magnetic field. © 2013 American Physical Society.


Simonov Y.A.,Institute of Theoretical and Experimental Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Spin interactions in a relativistic quark-antiquark system in a magnetic field is considered in the framework of the relativistic Hamiltonian, derived from the QCD path integral. The formalism allows us to separate spin-dependent terms from the basic spin-independent interaction contained in the Wilson loop, and produce confining and gluon exchange interaction. As a result, one obtains a relativistic spin-spin interaction Vss generalizing its nonrelativistic analog. It is shown that in a large magnetic field eB, V ss modifies and produces hyperfine shifts which grow linearly with eB and preclude the use of perturbation theory. We also show that tensor forces for eB≠0 are active in all meson states but do not grow with eB. © 2013 American Physical Society.


Zenkevich Y.,Institute of Theoretical and Experimental Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

Nekrasov functions were conjectured in Mironov and Morozov (2009) [1] to be related to exact Bohr-Sommerfeld periods of quantum integrable systems. This statement was thoroughly checked for the case of the pure SU(Nc) gauge theory in Mironov and Morozov (2009) [2] and Popolitov (2010) [3]. Here we successfully perform a set of checks in the case of gauge group SU(Nc) with additional Nf fundamental hypermultiplets. We show that the Baxter equation for the spin chain gives the same quantum periods as the one for the Gaudin system in this case. © 2011 Elsevier B.V.


Simonov Y.,Institute of Theoretical and Experimental Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

Neutral systems containing two identical particles, in homogeneous magnetic field are shown to obey exact factorizable solutions both in nonrelativistic and relativistic formalism, similarly to the neutral two-body systems. Concrete examples of the helium atom and the neutron as a (ddu) system are considered. © 2013.


Bork L.V.,Institute of Theoretical and Experimental Physics
Journal of High Energy Physics | Year: 2013

In this paper a supersymmetric version of a generalized unitarity cut method in application to MHV and NMHV for form factors of operators from the N=4 SYM stress-tensor current supermultiplet T AB at one loop is discussed. The explicit answers for 3 and 4 point NMHV form factors at tree and one loop level are obtained. The general structure of n-point NMHV form factor at one loop is discussed as well as the relation between form factor with super momentum equal to zero and the logarithmic derivative of the superamplitude with respect to the coupling constant. © 2012 SISSA, Trieste, Italy.

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