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A. Sissakian

Publications and source records attributed to A. Sissakian.

At least 19 recordsLinked to original sources
arXiv2012

Recent advances in Ti and Nb explosion welding with stainless steel for 2K operating (ILC Program)- To the proceedings of LCWS11

The world first samples 0f Ti+SS and Nb+SS joints were manufactured by an explosion welding technology demonstrating a high mechanic properties and leak absence at 4.6 x 10^{-9} atm-cc/sec. Residual stresses in bimetallic joints resulting from explosion welding measured by neutron diffraction method are quite high (~1000 MPa). Thermal tempering of explosion welded Ti+SS and Nb+SS specimens leads to complete relaxation of internal stresses in Ti,Nb and Stainless steel and makes the transition elements quite serviceable.

physics.ins-det↗
arXiv2009

Polarized parton distributions from NLO QCD analysis of world DIS and SIDIS data

The combined analysis of polarized DIS and SIDIS data is performed in NLO QCD. The new parametrization on polarized PDFs is constructed. The uncertainties on PDFs and their first moments are estimated applying the modified Hessian method. The especial attention is paid to the impact of novel SIDIS data on the polarized distributions of light sea and strange quarks. In particular, the important question of polarized sea symmetry is studied in comparison with the latest results on this subject.

hep-ph↗
arXiv2008

Transversity and T-odd PDFs from Drell-Yan processes with $pp$, $pD$ and $DD$ collisions

We estimate the single-spin asymmetries (SSA) which provide the access to transversity as well as to Boer-Mulders and Sivers PDFs via investigation of the single-polarized Drell-Yan (DY) processes with $ pp$, $pD$ and $DD$ collisions available to RHIC, NICA, COMPASS, and J-PARC. The feasibility of these SSA is studied with the new generator of polarized DY events. The performed estimations demonstrate that there exist the such kinematical regions where SSA are presumably measurable. The most useful for PDFs extraction are the limiting kinematical ranges, where one can neglect the sea PDFs contributions which occur at large values of Bjorken x. It is of interest that on the contrary to the Sivers PDF, the transversity PDF is presumably accessible only in the especial kinematical region. On the contrary to the option with the symmetric collider mode (RHIC, NICA), this is of importance for the COMPASS experiment and the future J-PARC facility where the fixed target mode is available.

hep-ph↗
arXiv2008

On the First Order Phase Transitions Signal in Multiple Production Processes

We offer the parameter, interpreted as the "chemical potential", which is sensitive to the first order phase transition: it must decrease with number of evaporating (produced) particles (hadrons) if the (interacting hadron or/and QCD plasma) medium is boiling and it increase if no phase transition occur. The main part of the paper is devoted to the question: how one can measure the "chemical potential" in the hadron inelastic processes. Our definition of this parameter is quite general but assumes that the hadron multiplicity is sufficiently large. The simple transparent phenomenological lattice gas model is considered for sake of clarity only.

hep-ph↗
arXiv2007

On duality of Drell-Yan and J/psi production processes

It is studied the model on J/psi production allowing to extract parton distribution functions (PDFs) from the combined analysis with both data on Drell-Yan and J/psi production processes. It is shown that this, so attractive from theoretical point of view, model, can be safely used in the low energy region E<100 GeV. The significance of gluon contributions to the J/psi cross-sections is investigated. The obtained results in the high energy region occur to be rather surprising.

hep-ph↗
arXiv2006

Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1

An ensemble of multi-layer scintillators is discussed as an option of the high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic measurements of neutrino-less double beta decays. A prototype detector MOON-1, which consists of 6 layer plastic-scintillator plates, was built to study the sensitivity of the MOON-type detector. The scintillation photon collection and the energy resolution, which are key elements for the high-sensitivity experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region, respectively. The multi-layer plastic-scintillator structure with good energy resolution as well as good background suppression of beta-gamma rays is crucial for the MOON-type detector to achieve the inverted hierarchy neutrino mass sensitivity.

nucl-ex↗
arXiv2005

Transversity and its accompanying T-odd distribution from Drell-Yan processes with pion-proton collisions

It is studied the possibility of direct extraction of the transversity and its accompanying T-odd parton distribution function (PDF) from Drell-Yan (DY) processes with unpolarized pion beam and with both unpolarized and transversely polarized proton targets. At present, such a measurement can be performed on the COMPASS experiment at CERN. The preliminary estimations performed for COMPASS kinematic region demonstrate that it is quite real to extract both transversity and its accompanying T-odd PDF in the COMPASS conditions

hep-ph↗
arXiv2004

On elimination of the Gribov ambiguity

We find a strong coupling expansion around the non-trivial extremum of the Yang-Mills action. It is shown that the developed formalism is the Gribov ambiguity free since each order of the developed perturbation theory is transparently gauge invariant. The success is a consequence of the restriction: calculations are not going beyond the norm of the $S$-matrix element.

hep-th↗
arXiv2002

QCD multi-jet processes and the multiplicity asymptotics

We will offer the formal arguments that the very high multiplicity (VHM) events are defined by the heavy QCD jets and, with exponential over multiplicity accuracy, the number of jets must decrease with the increasing multiplicity. This must rise the mean transverse momentum of secondaries with multiplicity. The effectiveness of the LLA in the VHM domain is also discussed.

hep-ph↗
arXiv2002

Symmetries, Variational Principles and Quantum Dynamics

The role of symmetries in formation of quantum dynamics is discussed. A quantum version of the d'Alambert's principle is proposed to take into account symmetry constrains for quantum case. It is noted that in this approach one can find, in four space-time dimensions, the free of divergences quantum field theory.

hep-ph↗
arXiv2001

Why the Very High Multiplicity events are rare

The possibility to suppress the nonperturbative effects choosing the vary high multiplicity final state is discussed. The theoretical uncertainties and the experimental observable consequence of this choice are discussed.

hep-ph↗
arXiv2001

Very High Multiplicity Hadron Processes

The paper contains a description of a first attempt to understand the extremely inelastic high energy hadron collisions, when the multiplicity of produced hadrons considerably exceeds its mean value. Problems with existing model predictions are discussed. The real-time finite-temperature $S$-matrix theory is built to have a possibility to find model-free predictions. This allows to include the statistical effects into consideration and build the phenomenology. The questions to experiment are formulated at the very end of the paper.

hep-ph↗
arXiv2001

Quantization of Solitons in Coset Space

The perturbation theory around the soliton fields of the sin-Gordon model is developed in the coset space. It is shown by explicit calculations that all corrections to the topological soliton contribution are canceled exactly.

hep-ph↗
arXiv2001

Yang-Mills Fields Quantization in the Factor Space

The perturbation theory over inverse interaction constant $1/g$ is constructed for Yang-Mills theory. It is shown that the new perturbation theory is free from the gauge ghosts and Gribov's ambiguities, each order over $1/g$ presents the gauge-invariant quantity. It is remarkable that offered perturbation theory did not contain divergences, at least in the vector fields sector, and no renormalization procedure is necessary for it.

hep-ph↗
arXiv2000

Multiplicity distribution tails at high eneries energies

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.

hep-ph↗
arXiv2000

Multiplicity distribution tails at high energies

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.

hep-ph↗
arXiv2000

Dual-Resonance Model and Multiple Production

The very high multiplicity (VHM) processes are considered to investigate consequences of the dual resonance models reach (exponential) mass spectrum. The virial decomposition is developed for description of the produced particles short-rang (resonance) correlations. It is shown that the reach mass spectrum is able to do more flat the VHM distribution: $\s_n=O(e^{-n})$ up to multiplicities $n\simeq\bar{n}^2$, $\bar{n}$ is the mean multiplicity. But for $n>>\bar{n}^2$ one should expect $\s_n<O(e^{-n})$.

hep-ph↗