Femtoscopy of Pb-Pb and pp collisions at the LHC with the ALICE experiment

We report on the results of femtoscopic analysis of Pb-Pb collisions at sqrt(s_NN)=2.76 TeV and pp collisions at sqrt(s)=0.9, 2.76 and 7 TeV with identical pions and kaons. Detailed femtoscopy studies in heavy-ion collisions at SPS and RHIC have shown that emission region sizes ("HBT radii") decrease with increasing pair transverse momentum k_T, which is understood as a manifestation of the collective behavior of matter. The trend was predicted to persist at the LHC. The data from Pb-Pb collisions confirm the existence of a flowing medium and provide strict constraints on the dynamical models. Similar analysis is carried out for pp collisions for pions and kaons and qualitative similarities to heavy-ion data are seen, especially in collisions producing large number of particles. The observed trends give insight into the soft particle production mechanism in pp collisions. 3D radii were also found to universally scale with event multiplicity in heavy-ion collisions. We extend the range of multiplicities both upwards with the Pb-Pb data and downwards with the pp data to test the scaling in new areas. In particular the high multiplicity pp collisions reach particle densities comparable to the ones measured in peripheral Cu-Cu and Au-Au collisions at RHIC. This allows for the first time to directly compare freeze-out sizes for systems with very different initial states.Comment: 8 pages, 5 figures, Proceedings of the Quark Matter 2011 plenary tal

Evidence for Hydrodynamic Evolution in Proton-Proton Scattering at LHC Energies

In $pp$ scattering at LHC energies, large numbers of elementary scatterings will contribute significantly, and the corresponding high multiplicity events will be of particular interest. Elementary scatterings are parton ladders, identified with color flux-tubes. In high multiplicity events, many of these flux tubes are produced in the same space region, creating high energy densities. We argue that there are good reasons to employ the successful procedure used for heavy ion collisions: matter is assumed to thermalizes quickly, such that the energy from the flux-tubes can be taken as initial condition for a hydrodynamic expansion. This scenario gets spectacular support from very recent results on Bose-Einstein correlations in $pp$ scattering at 900 GeV at LHC.Comment: 11 pages, 20 figure

Разработка унифицированного программного алгоритма подготовки к перевозке крупногабаритных грузов

Improving the processes of cargo transportation leads to expansion of capabilities of carriers, manufacturers, and customers, which in turn results in an increase in the need for transportation of goods.Increasing the speed and quality of operations at the stages of preparation for oversized cargo delivery will reduce the cost of delivering such cargo, will attract investment in various sectors of the economy.Hence, relevant is the research topic considered as the purpose of the study described in the paper and inspired by the need to develop and apply a harmonised software algorithm for preparing to transport the oversized cargo.The study was based on theoretical methods of analysis of domestic and foreign sources of information on preparation for transportation of oversized cargo. Aspects related to preparation for delivery of oversized cargo were sequentially considered, and a draft algorithm was developed to automate the planning of the stages of transportation of oversized cargo.The application of the proposed automated unified algorithm for preparing for the transport process is expected to reduce the labour and time costs of the process of displacement of oversized cargo as a whole and the risks of making a technological error at the stages of preparing for transporting oversized cargo, which might result in financial and reputational losses.Совершенствование процесса транспортировки приво­дит к расширению возможностей перевозчиков, производи­телей и заказчиков, что в свою очередь ведёт к увеличению потребности в перевозке грузов.Повышение скорости и качества прохождения этапов подготовки к перевозке крупногабаритных грузов позволит снизить затраты на доставку такого груза, приведёт к привлечению инвестиций в различные отрасли экономики.В этой связи актуальной научной проблемой, рассмот­рение которой составляет цель исследования, является необходимость разработки и применения унифицированного программного алгоритма подготовки к перевозке крупнога­баритных грузов.Использовались теоретические методы изучения и анализа отечественных и зарубежных источников ин­формации о подготовке к транспортировке крупногаба­ритных грузов.В ходе исследования последовательно рассмотрены аспекты, касающиеся подготовки к транспортировке круп­ногабаритного груза, и разработан проект алгоритма для автоматизации планирования этапов перевозки крупнога­баритных грузов.При использовании предлагаемого автоматизированно­го унифицированного алгоритма подготовки к транспорт­ному процессу предполагается снижение трудовых, времен­ных затрат процесса транспортировки крупногабаритного груза в целом и снижение рисков допущения технологической ошибки на этапах подготовки к транспортировке крупнога­баритного груза, которая может привести к финансовым и репутационным потерям

Hanbury Brown-Twiss interferometry and second-order correlations of inflaton quanta

The quantum theory of optical coherence is applied to the scrutiny of the statistical properties of the relic inflaton quanta. After adapting the description of the quantized scalar and tensor modes of the geometry to the analysis of intensity correlations, the normalized degrees of first-order and second-order coherence are computed in the concordance paradigm and are shown to encode faithfully the statistical properties of the initial quantum state. The strongly bunched curvature phonons are not only super-Poissonian but also super-chaotic. Testable inequalities are derived in the limit of large angular scales and can be physically interpreted in the light of the tenets of Hanbury Brown-Twiss interferometry. The quantum mechanical results are compared and contrasted with different situations including the one where intensity correlations are the result of a classical stochastic process. The survival of second-order correlations (not necessarily related to the purity of the initial quantum state) is addressed by defining a generalized ensemble where super-Poissonian statistics is an intrinsic property of the density matrix and turns out to be associated with finite volume effects which are expected to vanish in the thermodynamic limit.Comment: 42 pages, 3 included figures; corrected typos; to appear in Physical Review

Imaging Three Dimensional Two-particle Correlations for Heavy-Ion Reaction Studies

We report an extension of the source imaging method for analyzing three-dimensional sources from three-dimensional correlations. Our technique consists of expanding the correlation data and the underlying source function in spherical harmonics and inverting the resulting system of one-dimensional integral equations. With this strategy, we can image the source function quickly, even with the finely binned data sets common in three-dimensional analyses.Comment: 13 pages, 11 figures, submitted to Physical Review

Deciphering nonfemtoscopic two-pion correlations in p+pp+p collisions with simple analytical models

A simple model of nonfemtoscopic particle correlations in proton-proton collisions is proposed. The model takes into account correlations induced by the conservation laws as well as correlations induced by minijets. It reproduces well the two-pion nonfemtoscopic correlations of like-sign and unlike-sign pions in proton-proton collision events at $\sqrt{s} = 900$ GeV analyzed by the ALICE Collaboration. We also argue that similar nonfemtoscopic correlations can appear in the hydrodynamic picture with event-by-event fluctuating nonsymmetric initial conditions that are typically associated with nonzero higher-order flow harmonics.Comment: 21 pages, 10 figures, misprints correcte

Anomalously strong pinning of the filling factor nu=2 in epitaxial graphene

We explore the robust quantization of the Hall resistance in epitaxial graphene grown on Si-terminated SiC. Uniquely to this system, the dominance of quantum over classical capacitance in the charge transfer between the substrate and graphene is such that Landau levels (in particular, the one at exactly zero energy) remain completely filled over an extraordinarily broad range of magnetic fields. One important implication of this pinning of the filling factor is that the system can sustain a very high nondissipative current. This makes epitaxial graphene ideally suited for quantum resistance metrology, and we have achieved a precision of 3 parts in 10^10 in the Hall resistance quantization measurements