Bethe Subalgebras in Twisted Yangians

We study analogues of the Yangian of the Lie algebra $gl_N$ for the other classical Lie algebras $so_N$ and $sp_N$. We call them twisted Yangians. They are coideal subalgebras in the Yangian $Y(gl_N)$ of $gl_N$ and admit homomorphisms onto the universal enveloping algebras $U(so_N)$ and $U(sp_N)$ respectively. In every twisted Yangian we construct a family of maximal commutative subalgebras parametrized by the regular semisimple elements of the corresponding classical Lie algebra. The images in $U(so_N)$ and $U(sp_N)$ of these subalgebras are also maximal commutative.Comment: 26 pages, amstex, misprints correcte

Atomic Structure in the Vicinity of Nanovoids and Features of These Defects

Many properties of metals are determined by the defects, such as point defects, their complexes and nanovoids, whereas properties of these defects are generally related to the changes in atomic structure in the vicinity of these defects. In this work, recently developed approach is applied to simulate vacancy complexes and nanovoids. A developed model on the basis of Molecular Statics is used to investigate the atomic structure peculiarities in the vicinity of vacancy complexes and nanovoids, and the atomic displacements in the elastic medium surrounding the computational cell are determined in a self-consistent manner. The second part of the work is concerned with the study of atomic structure changes under temperature increasing within the new model based on Molecular Dynamics. Within the scope of this model, coordinates of the atoms in the area nearby of vacancy complex or nanovoid surface are averaged, during a simulation. Obtained mean positions of atoms are used for calculation of averaged interatomic distances; that allows determining lattice-parameter temperature dependence and then temperature-determined changes of atomic structure in the defects’ vicinity. Simulation is performed for various f.c.c. and b.c.c. metals. For these metals, thermal expansion data are obtained, and the change of atomic structure in the defects’ vicinity is determined from temperature increase.Багато властивостей металів визначаються дефектами, їхніми комплексами і нанопорами, тоді як властивості цих дефектів, взагалі кажучи, пов’язані зі змінами атомної структури поблизу цих дефектів. У даній роботі нещодавно запропонований підхід застосовується для симуляції вакансійних комплексів та нанопор. Нещодавно запропонована модель на основі методи молекулярної статики використовується для дослідження особливостей атомної структури в околі вакансійних комплексів і нанопор, а також уможливлює самоузгодженим чином знайти атомні зміщення у пружньому середовищі, яке оточує розрахункову комірку. Другу частину роботи присвячено вивченню змін атомної структури зі зростанням температури, шляхом застосування нової моделі, яка ґрунтується вже на молекулярній динаміці. В рамках даної моделі координати атомів поблизу вакансійних комплексів або поверхні нанопор усереднюються в процесі симуляції. Одержані середні положення атомів використовуються для розрахунку усереднених міжатомних відстаней, що уможливлює спочатку одержати температурну залежність параметра ґратниці, а потім обумовлені температурою зміни атомної структури в околі дефектів. Моделювання проводилося для різних ГЦК- та ОЦК-металів. Для цих металів одержано дані для теплового розширення, а також визначено зміну атомної структури в околі дефектів при зростанні температури.Многие свойства металлов определяются дефектами, их комплексами и нанопорами, тогда как свойства этих дефектов, вообще говоря, связаны с изменениями атомной структуры вблизи этих дефектов. В данной работе недавно предложенный подход применяется для симуляции вакансионных комплексов и нанопор. Недавно предложенная модель на основе метода молекулярной статики используется для исследования особенностей атомной структуры в окрестности вакансионных комплексов и нанопор, а также позволяет самосогласованным образом найти атомные смещения в упругой среде, окружающей расчётную ячейку. Вторая часть работы посвящена изучению изменений атомной структуры с ростом температуры путём применения новой модели, основанной уже на молекулярной динамике. В рамках данной модели координаты атомов вблизи вакансионных комплексов или поверхности нанопор усредняются в процессе симуляции. Полученные средние положения атомов используются для расчёта усреднённых межатомных расстояний, что позволяет сначала получить температурную зависимость параметра решётки, а затем обусловленные температурой изменения атомной структуры в окрестности дефектов. Моделирование проводилось для различных ГЦК- и ОЦК-металлов. Для этих металлов получены данные для теплового расширения, а также определено измен

Mesoscopic fluctuations of Coulomb drag between quasi-ballistic 1D-wires

Quasiballistic 1D quantum wires are known to have a conductance of the order of 2e^2/h, with small sample-to-sample fluctuations. We present a study of the transconductance G_12 of two Coulomb-coupled quasiballistic wires, i.e., we consider the Coulomb drag geometry. We show that the fluctuations in G_12 differ dramatically from those of the diagonal conductance G_ii: the fluctuations are large, and can even exceed the mean value, thus implying a possible reversal of the induced drag current. We report extensive numerical simulations elucidating the fluctuations, both for correlated and uncorrelated disorder. We also present analytic arguments, which fully account for the trends observed numerically.Comment: 10 pages including 7 figures. Minor changes according to referee report. Accepted for PR

Full counting statistics of information content

We review connections between the cumulant generating function of full counting statistics of particle number and the R\'enyi entanglement entropy. We calculate these quantities based on the fermionic and bosonic path-integral defined on multiple Keldysh contours. We relate the R\'enyi entropy with the information generating function, from which the probability distribution function of self-information is obtained in the nonequilibrium steady state. By exploiting the distribution, we analyze the information content carried by a single bosonic particle through a narrow-band quantum communication channel. The ratio of the self-information content to the number of bosons fluctuates. For a small boson occupation number, the average and the fluctuation of the ratio are enhanced.Comment: 16 pages, 5 figure

Quantum-critical dynamics of the Skyrmion lattice

Near to filling fraction nu=1, the quantum Hall ferromagnet contains multiple Skyrmion spin excitations. This multi-Skyrmion system has a tremendously rich quantum-critical structure. This is simplified when Skyrmions are pinned by disorder. We calculate the nuclear relaxation rate in this case and compare the result with experiment. We discuss how such measurements may be used to further probe the quantum-critical structure of the multi-Skyrmion system

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The yield of charged particles associated with high-$p_{\rm T}$ trigger particles ($8 < p_{\rm T} < 15$ GeV/$c$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_{\rm T}> 3$ GeV/$c$ on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/350

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388