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I. V. Anikin

Publications and source records attributed to I. V. Anikin.

At least 73 records · Page 4Linked to original sources
arXiv2009

On the description of exclusive processes beyond the leading twist approximation

We describe hard exclusive processes beyond the leading twist approximation in a framework based on the Taylor expansion of the amplitude around the dominant light-cone directions. This naturally introduces an appropriate set of non-perturbative correlators whose number is minimalized after taking into account QCD equations of motion and the invariance under rotation on the light-cone. We examplify this method at the twist 3 level and show that the coordinate and momentum space descriptions are fully equivalent.

hep-ph↗
arXiv2009

Hard diffractive processes and non-perturbative matrix elements beyond leading twist: rhoT-meson production

Within the kt-factorization approach, we evaluate the impact factor of the transition gamma* -> rhoT taking into account the twist 3 contributions. We show that a gauge invariant expression is obtained with the help of QCD equations of motion. More generally, relying on these equations and on the invariance under rotation on the light-cone of the factorized amplitude, the non-perturbative Distribution Amplitudes can be reduced to a minimal set. This opens the way to a consistent treatment of factorization for exclusive processes with a transversally polarized vector meson. We prove the equivalence of two proposed parametrizations of the rhoT distribution amplitudes.

hep-ph↗
arXiv2009

Photon-photon collision: ambiguity and duality in QCD factorization theorem

We discuss duality in ``two-photon''-like processes in the scalar $φ^3_E$ model and also in the process $γ^*γ\toππ$ in QCD. Duality implies the equivalence between two distinct nonperturbative mechanisms. These two mechanisms, one involving a twist-3 Generalized Distribution Amplitude, the other employing a leading-twist Transition Distribution Amplitude, are associated with different regimes of factorization. In the kinematical region, where the two mechanisms overlap, duality is observed for the scalar $φ^3_E$ model, while in the QCD case the appearance of duality turns out to be sensitive to the particular nonperturbative model applied and can, therefore, be used as a tool for selecting the most appropriate one.

hep-ph↗
arXiv2008

Duality between different mechanisms of QCD factorization in γ^*γcollisions

We study the phenomenon of duality in hard exclusive reactions to which QCD factorization applies. Considering "two-photon"-like processes in the scalar $ϕ^3_E$ model and also hadron-pair production from the collisions of a real (transversely polarized) and a highly virtual, longitudinally polarized, photon in QCD, we identify two regimes of factorization each of them associated with a distinct nonperturbative mechanism. One mechanism involves twist-3 Generalized Distribution Amplitudes, whereas the other one employs leading-twist Transition Distribution Amplitudes. In the case of the scalar $ϕ^3_E$ model, we find duality in that kinematical region where the two mechanisms overlap. In the QCD case, the appearance of duality is sensitive to the particular nonperturbative model applied and can, therefore, be used as an additional adjudicator.

hep-ph↗
arXiv2008

Duality and Factorization Theorem in QCD

We find that in "two-photon"-like processes in the scalar $φ^3_E$ model and also in hadron-pair production arising from the collisions of a real (transversely polarized) and a highly virtual, longitudinally polarized, photon in QCD, there is duality between two distinct nonperturbative mechanisms. These two mechanisms, one involving a twist-3 Generalized Distribution Amplitude, the other employing a leading-twist Transition Distribution Amplitude, are associated with different regimes of factorization. In the kinematical region, where the two mechanisms overlap, duality is observed for the scalar $φ^3_E$ model, while in the QCD case the appearance of duality turns out to be sensitive to the particular nonperturbative model applied and can, therefore, be used as a tool for selecting the most appropriate one.

hep-ph↗
arXiv2008

gamma* -> rhoT impact factor with twist three accuracy

We evaluate the impact factor of the transition gamma* -> rhoT taking into account the twist 3 contributions. We show that a gauge invariant expression is obtained with the help of QCD equations of motion. Our results are free of end-point singularities. This opens the way to a consistent treatment of factorization for exclusive processes with a transversally polarized vector meson.

hep-ph↗
arXiv2008

Dispersion relations and QCD factorization in hard reactions

We study analytical properties of the hard exclusive process amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with the subtraction constant determined by the Polyakov-Weiss $D$-term.

hep-ph↗
arXiv2007

Dispersion relations and subtractions in hard exclusive processes

We study analytical properties of the hard exclusive processes amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with the subtraction constant determined by the Polyakov-Weiss $D$-term. The relation of this constant to the fixed pole contribution found by Brodsky, Close and Gunion and defined by parton distributions is proved, while its manifestation is spoiled by the small $x$ divergence. The continuation to the real photons limit is considered and the numerical correspondence between lattice simulations of $D$-term and low energy Thomson amplitude is found.

hep-ph↗
arXiv2006

Recent and future experimental evidences for exotic mesons in hard reactions

The QCD analysis of the recent experimental data (L3@LEP) of the hard exclusive $ρρ$ production in two photon collisions shows that these data can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$. We also argue that hard exclusive reactions are a powerful tool for an experimental study of exotic hybrid mesons with $J^{PC}=1^{-+}$.

hep-ph↗
arXiv2006

Hard Electroproduction of Hybrid Mesons

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic $J^{PC}=1^{-+}$ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, {\it i.e.} as $1/Q^2$. This is due to the non-vanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next--to--leading order in $α_{S}$ and we explore the consequences of fixing the renormalization scale ambiguity through the BLM procedure.

hep-ph↗
arXiv2006

On exotic hybrid meson production in gamma* gamma collisions

We present a theoretical study of exotic hybrid meson (JPC=1-+) production in photon-photon collisions where one of the photons is deeply virtual, including twist 2 and twist 3 contributions. We calculate the cross section of this process which turns out to be large enough to imply sizeable counting rates in the present high luminosity electron-positron colliders. We emphasize theimportance of the pi eta decay channel for the detection of the hybrid meson candidate pi_1(1400) and calculate the cross section and the angular distribution for pi eta pair production in the unpolarized case. This angular distribution is a useful tool for disentangling the hybrid meson signal from the background. Finally, we calculate the single spin asymmetry associated with one initial longitudinally polarized lepton.

hep-ph↗
arXiv2005

Do L3 data indicate the existence of an isotensor meson ?

The QCD analysis of the hard exclusive production of $ρ^+ρ^-$ and $ρ^0ρ^0$ mesons in two photon collisions shows that the recent experimental data obtained by the L3 Collaboration at LEP can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$.

hep-ph↗
arXiv2005

Search for isotensor exotic meson and twist 4 contribution to $γ^*γ\toρρ$

We present a theoretical estimate for the cross-section of exclusive $ρ^+ρ^-$ and $ρ^0ρ^0$-meson production in two photon collisions when one of the initial photons is highly virtual. We focus on the discussion of the twist 4 contributions which are related to the production of an exotic isospin 2 resonance of two $ρ$ mesons. Our analysis shows that the recent experimental data obtained by the L3 Collaboration at LEP can be understood as a signal for the existence of an exotic isotensor resonance with a mass around $1.5 {\rm GeV}$.

hep-ph↗
arXiv2005

On BLM scale fixing in exclusive processes

We discuss the BLM scale fixing procedure in exclusive electroproduction processes in the Bjorken regime. We show that in the case of vector meson production the usual way to aplly the BLM method fails due to singularities present in equations fixing the BLM scale. We argue that the BLM scale should be extracted from the squared amplitudes which are directly related to observables.

hep-ph↗
arXiv2005

$πη$ pair hard electroproduction and exotic hybrid mesons

We show that hard electroproduction is a promising way to study exotic hybrid mesons, in particular through the hybrid decay channel $H \to πη$. We discuss the $πη$ generalized distribution amplitude, calculate the production amplitude and propose a forward-backward asymmetry as a signal for the hybrid meson production.

hep-ph↗