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A. M. Snigirev

Publications and source records attributed to A. M. Snigirev.

At least 37 records · Page 2Linked to original sources
arXiv2015

Angular dihadron correlations as interplay of elliptic and triangular flows

The hybrid model HYDJET++, which combines soft and hard components, is employed for the analysis of dihadron angular correlations measured in PbPb collisions at center-of-mass energy sqrt(s_NN) = 2.76 TeV. The model allows for study both individual contributions and mutual influence of lower flow harmonics, v_2 and v_3, on higher harmonics and dihadron angular correlations. It is shown that the typical structure called ridge in dihadron angular correlations in a broad pseudorapidity range could appear just as interplay of v_2 and v_3. Central, semi-central and semi-peripheral collisions were investigated. Comparison of model results with the experimental data on dihadron angular correlations is presented for different centralities and transverse momenta p_T.

hep-ph↗
arXiv2015

On jet structure in heavy ion collisions

The LHC data on jet fragmentation function and jet shapes in PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the frameworks of PYQUEN jet quenching model. A specific modification of longitudinal and radial jet profiles in most central PbPb collisions as compared with pp data is close to that obtained with PYQUEN simulations taking into account wide-angle radiative and collisional partonic energy loss. The contribution of radiative and collisional loss to the medium-modified intra-jet structure is estimated.

hep-ph↗
arXiv2015

Associated $W^{\pm}D^{(*)}$ production at the LHC and prospects to observe double parton interactions

Associated production of charged gauge bosons and charged charmed mesons at the LHC is considered in the framework of $k_T$-factorization approach. Theoretical predictions are compared with ATLAS data, and reasonably good agreement is found. Predictions on the same-sign $W^{\pm}D^{\pm}$ configurations are presented including single parton scattering and double parton scattering contributions. The latter are shown to dominate over the former, thus giving evidence that the proposed process can serve as another indicator of double parton interactions.

hep-ph↗
arXiv2014

Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model

The LHC data on azimuthal anisotropy harmonics from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in the framework of the HYDJET++ model. The cross-talk of elliptic $v_2$ and triangular $v_3$ flow in the model generates both even and odd harmonics of higher order. Comparison with the experimental data shows that this mechanism is able to reproduce the $p_{\rm T}$ and centrality dependencies of quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ flows.

nucl-th↗
arXiv2014

Hexagonal flow v_6 as a superposition of elliptic v_2 and triangular v_3 flows

Partial contributions of elliptic v_2 and triangular v_3 flows to the hexagonal v_6 flow are studied within the HYDJET++ model for Pb+Pb collisions at sqrt{s}=2.76 TeV. Scaling of the ratio v_6^{1/6}{Psi_2} / v_2^{1/2}{Psi_2} in the elliptic flow plane, Psi_2, is predicted in the range 1 < p_T < 4 GeV/c for semicentral and semiperipheral collisions. Jets increase this ratio by about 10% and also cause its rise at p_T > 3.5 GeV/c. The part of v_6 coming from v_2 is instantly increasing as the reaction becomes more peripheral, whereas the contribution of v_3 to v_6 drops. This behavior explains the experimentally observed increase of correlations between second and sixth harmonics and decrease of correlations between third and sixth harmonics with rising impact parameter $b$. Our study favors the idea that basic features of the hexagonal flow can be understood in terms of the interplay of elliptic and triangular flows.

hep-ph↗
arXiv2013

Non-Abelian color fields from relativistic color charge configurations in the classical limit

We study the dynamics of color fields as generated by simple configurations of relativistic particles with Abelian and non-Abelian (SU(2)) charges in the classical limit. We find that chromodynamic (non-Abelian) systems generally show Coulomb-like features by analogy with electrodynamics. A peculiar feature in the non-Abelian case is the additional strength of the chromoelectric and chromomagnetic fields caused by the contribution of changing the color charge. This change of color SU(2) charges results in a rotation of the color vector which is getting very fast at close partonic distances. The presence of this non-Abelian additional term in the chromoelectric and chromomagnetic fields creates a 'color charge glow', which is manifested as a distinct color wave disturbance arising due to the finite distance at which the color interaction becomes active. This situation may be relevant to the hadronization phase in ultrarelativistic heavy-ion collisions, where the partonic state is governed by strong local color fluctuations.

nucl-th↗
arXiv2013

Towards azimuthal anisotropy of direct photons

Intensive radiation of magnetic bremsstrahlung type (synchrotron radiation) resulting from the interaction of escaping quarks with the collective confining colour field is discussed as a new possible mechanism of observed direct photon anisotropy.

hep-ph↗
arXiv2013

Interparticle correlations in the production of J/ψpairs in proton-proton collisions

We focus on the problem of disentangling the single (SPS) and double (DPS) parton scattering modes in the production of \J pairs at the LHC conditions. Our analysis is based on comparing the shapes of the differential cross sections and on studying their behavior under imposing kinematical cuts. On the SPS side, we consider the leading-order ${\cal O}(α_s^4)$ contribution with radiative corrections (taken into account in the framework of the \ktf approach) and the subleading ${\cal O}(α_s^6)$ contribution from \pd ~gluon-gluon scattering represented by one gluon exchange and two gluon exchange mechanisms. We come to the conclusion that disentangling the SPS and DPS modes is rather difficult on the basis of azimuthal correlations, while the rapidity difference looks more promising, provided the acceptance of the experimental detectors has enough rapidity range.

hep-ph↗
arXiv2012

Double parton scattering in double logarithm approximation of perturbative QCD

Using the explicit form of the known single distribution functions (the Green's functions) in the double logarithm approximation of perturbative QCD, we analyze the structure of splitting diagrams as a source of double parton perturbative correlations in the proton. The related phenomenological effects are discussed for the conditions of the LHC experiments.

hep-ph↗
arXiv2012

Hadron spectra, flow and correlations in PbPb collisions at the LHC: interplay between soft and hard physics

The started LHC heavy ion program makes it possible to probe new frontiers of the high temperature Quantum Chromodynamics. It is expected that the role of hard and semi-hard particle production processes may be significant at ultra-high energies even for bulk properties of the created matter. In this paper, the LHC data on multiplicity, hadron spectra, elliptic flow and femtoscopic correlations from PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed in the framework of the HYDJET++ model. The influence of the jet production mechanism on these observables is discussed.

hep-ph↗
arXiv2011

Jet quenching pattern at LHC in PYQUEN model

The first LHC data on high transverse momentum hadron and dijet spectra in PbPb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed in the frameworks of PYQUEN jet quenching model. The presented studies for the nuclear modification factor of high-pT hadrons and the imbalance in dijet transverse energy support the supposition that the intensive wide-angular ("out-of-cone") medium-induced partonic energy loss is seen in central PbPb collisions at the LHC.

hep-ph↗
arXiv2011

A fresh look at double parton scattering

A revised formula for the inclusive cross section for double parton scattering in terms of the modified collinear two-parton distributions extracted from deep inelastic scattering is suggested. The possible phenomenological issues are discussed.

hep-ph↗
arXiv2010

Asymptotic behavior of double parton distribution functions

The double parton distribution functions are investigated in the region of small longitudinal momentum fractions in the leading logarithm approximation of perturbative QCD. It is shown that these functions have the factorization property in the case of one slow and one fast parton.

hep-ph↗
arXiv2010

Modeling the jet quenching, thermal resonance production and hydrodynamical flow in relativistic heavy ion collisions

The event topology in relativistic heavy ion collisions is determined by various multi-particle production mechanisms. The simultaneous model treatment of different collective nuclear effects at high energies (such as a hard multi-parton fragmentation in hot QCD-matter, thermal resonance production, hydrodynamical flows, etc.) is actual but rather complicated task. We discuss the simulation of the above effects by means of Monte-Carlo model HYDJET++.

hep-ph↗
arXiv2010

Possible indication to the QCD evolution of double parton distributions?

For the first time the process-independent parameter of double parton scattering, $σ_{\rm eff}^{\rm exp}$, has been measured newly in the D0 experiment at the three different resolution scales.If we interpret the measurement as a decrease of the effective cross section with a growth of the resolution scale it can indicate the QCD evolution of double parton distributions.

hep-ph↗