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Search Results: 1 - 10 of 90 matches for " Kuraev "
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QED Radiative Corrections to the Pionium Life Time
E. A. Kuraev
Physics , 1997,
Abstract: The lowest order QED radiative corrections to the cross-section of the recharged process of transition of two charged pions to two neutral ones and to the pionium life time are calculated in frames of scalar QED. It is argued that the ultraviolet cut--off of the loop momentum is to be chosen of order of $\rho$ meson mass. This fact permits to perform the calculation in frames of Effective Chiral Lagrangian theory with vector-meson dominance. The Coulomb factor corresponding to interaction in the initial state, shown, is to be removed to avoid the double counting. Resulting value of the radiative correction to the pionium life time is -0.25%.
Radiative Tail in $π_{e2}$ Decay and Some Comments on $μ-e$ Universality
E. A. Kuraev
Physics , 1996, DOI: 10.1134/1.567302
Abstract: The result of lowest-order perturbation theory calculations of the photon and positron spectra in radiative pion(e2) decay are generalized to all orders of perturbation theory using the structure-function method. An additional source of radiative corrections to the ratio of the positron and muon channels of pion decay, due to emission of virtual and real photons and pairs, is considered. It depends on details of the detection of the final particles and is large enough to be taken into account in theoretical estimates with a level of accuracy of 0.1%.
The two photon exchange amplitude in $ep$ and $e\mu $ elastic scattering: a comparison
Kuraev, E. A.;Tomasi-Gustafsson, E.
High Energy Physics - Phenomenology , 2008,
Abstract: In this note we give arguments in favor of the statement that the contribution of the box diagram calculated for electron muon elastic scattering can be considered an upper limit to electron proton scattering. As an exact QED calculation can be performed, this statement is useful for constraining model calculations involving the proton structure.
Radiative corrections to muon decay in leading and next to leading approximation for electron spectrum
Bartos, E.;Kuraev, E. A.;Secansky, M.
High Energy Physics - Phenomenology , 2008, DOI: 10.1134/S1547477109050033
Abstract: We have noted that the electron spectrum of muon decay in the leading logarithmic approximation calculated in two lowest orders of the perturbation theory in the paper of Berman (1958), can be reproduced by the parton language. This fact permits one to generalize the result to all orders of the perturbation theory using the structure function method.
Radiatively corrected lepton energy distributions in top quark decays $t \to bW^+ \to b(\ell^+ ν_\ell)$ and $t \to bH^+ \to b (τ^+ ν_τ)$ and single charged prong energy distributions from subsequent $τ^+$ decays
Ahmed Ali,Eduard A. Kuraev,Yury Bystritskiy
Physics , 2009, DOI: 10.1140/epjc/s10052-010-1300-z
Abstract: We calculate the QED and QCD radiative corrections to the charged lepton energy distributions in the dominant semileptonic decays of the top quark $t \to b W^+ \to b(\ell^+ \nu_\ell)$ $(\ell=e, \mu, \tau)$ in the standard model(SM), and for the decay $t \to b H^+ \to b(\tau^+ \nu_\tau)$ in an extension of the SM having a charged Higgs boson $H^\pm$ with $m_{H^\pm} < m_t -m_b$. The QCD corrections are calculated in the leading and next-to-leading logarithmic approximations, but the QED corrections are considered in the leading logarithmic approximation only. These corrections are numerically important for precisely testing the universality of the charged current weak interactions in $t$-quark decays. As the $\tau^+$ leptons arising from the decays $W^+ \to \tau^+ \nu_\tau$ and $H^+\to \tau^+ \nu_\tau$ are predominantly left- and right-polarised, respectively, influencing the energy distributions of the decay products in the subsequent decays of the $\tau^+$, we work out the effect of the radiative corrections on such distributions in the dominant (one-charged prong) decay channels $ \tau^+ \to \pi^+ \bar{\nu}_\tau, \rho^+ \bar{\nu}_\tau, a_1^+ \bar{\nu}_\tau$ and $\ell^+ \nu_\ell \bar{\nu}_\tau$. The inclusive $\pi^+$ energy spectra in the decay chains $t \to b(W^+,H^+) \to b (\tau^+ \nu_\tau) \to b (\pi^+ \bar{\nu}_\tau \nu_\tau +X)$ are calculated, which can help in searching for the induced $H^\pm$ effects at the Tevatron and the LHC.
Once more about the $ω\to 3π$ contact term
E. A. Kuraev,Z. K. Silagadze
Physics , 1995,
Abstract: The manifestations of the $\omega \to 3\pi$ contact term and its unitary partners are investigated in the framework of the chiral effective lagrangian theory with vector mesons. We conclude that nowadays the existence and magnitude of the contact term can be extracted neither from theory, nor experiment. The theoretical uncertainty is caused by the one-loop corrections. Some speculations about them lead to the generalized KSRF relation $\frac{f_\pi^2g^2_{\rho \pi \pi}}{m_\rho^2}=\frac{m_K}{2\sqrt{2} \pi f_\pi}$.
Evolution of chiral-odd spin-independent fracture functions in Quantum Cromodynamics
A. V. Belitsky,E. A. Kuraev
Physics , 1996, DOI: 10.1016/S0550-3213(97)00306-4
Abstract: We construct the evolution equations for the twist-3 chiral-odd spin independent fracture functions in QCD. The Gribov-Lipatov reciprocity relation is fulfilled at the one-loop level for the quasi-partonic two-particle cut vertices only. It is found that the rang of the anomalous dimensions matrix is infinite for any given moment of the three-parton fracture function as distinguished from the case of DIS-distributions where the rang of the matrix was finite and increases with the number of the moment. In the multicolour limit $N_c \to \infty$ the evolution equation for the quark-gluon-quark correlation function decouples from another equation in the system and becomes homogeneous provided we discard the quark mass effects. This fact provides an opportunity to find its analytic solution explicitly in nonlocal form similarly to the DIS.
Multiplicity distribution tails at high energies
E. A. Kuraev,J. Manjavidze,A. Sissakian
Physics , 2000,
Abstract: The idea that the hard channels may dominate in the very high multiplicity processes is investigated. Quantitative realization of the `hard Pomeron', deep inelastic scattering and large-angle annihilation mechanism combinations are considered in the pQCD frame for this purpose.
Multiplicity distribution tails at high eneries energies
E. A. Kuraev,J. Manjavidze,A. Sissakian
Physics , 2000,
Abstract: The idea that the hard channels may dominate in the very high multiplicity processes is investigated. Quantitative realization of the `hard Pomeron', deep inelastic scattering and large-angle annihilation mechanism combinations are considered in the pQCD frame for this purpose.
QED correction to radiative tail from elastic peak in DIS
I. Akushevich,E. Kuraev,B. Shaikhatdenov
Physics , 2000, DOI: 10.1103/PhysRevD.62.053016
Abstract: We calculate DIS cross section under kinematical requirements when a final hadron state is a single proton. The process in the lowest order is known as radiative tail from elastic peak. We take into account correction, coming from emission of virtual and soft real photons, to the amplitude of this process as well as the one, induced by emission of additional hard photon and a hard pair. Resulting contributions of these channels are presented in the leading and, partly, next-to-leading logarithmic approximations. Some general expressions for the photon contributions are given. Numerical results are presented for kinematical conditions of the current experiments on DIS.
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