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V. L. Morgunov

Publications and source records attributed to V. L. Morgunov.

10 recordsLinked to original sources
arXiv2003

Selection and reconstruction of the top quarks in the all-hadronic decays at a Linear Collider

A method of reconstruction of the top quarks produced in the process E+E- -> t\bar{t} -> 6 jets at a Linear Collider (LC) is proposed. The approach does not involve a kinematic fit, as well as assumptions on the invariant masses of the dijets originating from the decays of W bosons and, therefore, the method is expected to be less sensitive to theoretical and experimental uncertainties on the top-mass measurement than traditional reconstruction methods. For the first time, the reconstruction of the top quarks was investigated using the full LC detector simulation after taking into account the background arising from QCD multi-jet production.

hep-ex↗
arXiv1999

Rotating QCD string and the meson spectrum

The spectra of light-light and heavy-light mesons are described by spinless Salpeter equation and Dirac equation respectively, which predict linear dependence of the meson mass squared M^2 on angular momentum J and number of radial nodes n. Both spectra are computed by the WKB method and shown to agree with exact numerical data within few percent even for the lowest levels. The drawback of Salpeter and Dirac equation is that (inverse) Regge slopes do not coincide with the string ones, 2πσand πσrespectively, because the string dynamics is not taken into account properly. The lacking string rotation is introduced via effective Hamiltonian derived from QCD which generates linear Regge trajectories for light mesons with the correct string slope.

hep-ph↗
arXiv1999

Fine structure splittings of excited P and D states in charmonium

It is shown that the fine structure splittings of the $2 ^3P_J$ and $3 ^3P_J$ excited states in charmonium are as large as those of the $1^3P_J$ state if the same $α_s(μ)\approx 0.36$ is used. The predicted mass $M(2 ^3P_0)=3.84$ GeV appears to be 120 MeV lower that the center of gravity of the $2 ^3P_J$ multiplet and lies below the $D\bar D^*$ threshold. Our value of $M(2 ^3P_0)$ is approximately 80 MeV lower than that from the paper by Godfrey and Isgur while the differences in the other masses are $\la 20$ MeV. Relativistic kinematics plays an important role in our analysis.

hep-ph↗
arXiv1999

Determination of Alpha_s(1 GeV) from the charmonium fine structure

The strong coupling constant $α_s(μ)$ is extracted from the fits to charmonium spectrum and fine structure splittings. The relativistic kinematics is taken into account and relativistic corrections are shown to increase the matrix elements defining spin effects up to 40%. The value of $α_s(μ)$ at low-energy scale $μ=1.0 \pm 0.2 GeV$ was found to be $α_s(μ) = 0.38 \pm 0.03 (exp.) + 0.04 (theor.)$ which is about 50% lower than standard perturbative two-loop approximation and is in good agreement with the freezing $α_s$ behaviour.

hep-ph↗
arXiv1997

The Light-Cone nonperturbative dynamics of meson wave functions

The light-cone Hamiltonian, incorporating the nonperturbative dynamics of the $q\bar q$ system connected by the string is solved numerically. The spectrum is shown to coincide with that of the center-of-mass Hamiltonian within the accuracy of computation, displaying the expected degeneracies of the string states, but an overall shift due to different treatment of Z-graphs is obtained. The nonperturbative wave functions are calculated directly from the light-cone Hamiltonian for the first time, thus allowing the explicit estimation of nonperturbative effects in the parton model language. In this way one obtains the string contribution to the parton distributions and in the formfactors and structure functions.

hep-ph↗
arXiv1994

The magnitude of the gluon condensate and the masses of $c$ and $b$ quarks from the families of ${\cal J}$/$Ψ$ and $Υ$ mesons

It is shown that the model used in [1] for the description of the experimental function $R_c (s)$ in the form of a sum of $δ$-functions and the plateau contradicts the Wilson operator expansion (O.E.) in the terms due to the gluon condensate. A QCD model with an infinite number of vector mesons [12,13] does satisfy the requirements of the O.E. for masses and electronic widths resonances close to the experimental values. The region of allowable values of the masses of $c$ and $b$-quarks and the gluon condensate compatible with the O.E. is obtained (Figs. 2,3).

hep-ph↗