Critical behavior of higher cumulants of order parameter in the 3D-Ising universality class

QCD deconfinement phase transition is supposed to be the same universality class as the 3D-Ising model. According to the universality of critical behavior, the Binder-like ratios and ratios of higher cumulants of order parameter near the critical temperature in the 3D-Ising model are studied. The Binder-like ratio is shown to be a step function of temperature. The critical point is the intersection of the ratios of different system sizes between two platforms. The normalized cumulant ratios, like the Skewness and Kurtosis, do not diverge with correlation length, contrary to the corresponding cumulants. Possible applications of these characters in locating critical point in relativistic heavy ion collisions are discussed.     

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 color field is discussed as a new possible mechanism of observed direct photon anisotropy.     

Asymmetric azimuthal distribution of hadrons inside a jet from hadron-hadron collisions

We study the azimuthal asymmetric distribution of hadrons inside a high energy jet in the single-transverse polarized nucleon-nucleon scattering, coming from the Collins effect multiplied by the quark transversity distribution. We argue that the Collins function in this process is the same as that in the semi-inclusive deep inelastic scattering. The experimental study of this process will provide us with important information on the quark transversity distribution and test the universality of the fragmentation functions.     

Beam energy dependence of azimuthal anisotropy at RHIC-PHENIX

Recent PHENIX measurements of the elliptic (?? ₂) and hexadecapole (?? ₄) Fourier flow coefficients for charged hadrons as a function of transverse momentum (p _T ), collision centrality and particle species are presented and compared with results from the PHOBOS and STAR Collaborations respectively. The status of extensions to future PHENIX measurements at lower beam energies is also discussed.     

Influence of anisotropy constants of higher order on the magnetic reversal of uniaxial magnets

Within the framework of a simple model in which only homogeneous states of magnetization are considered, the influence of the constants of magnetic crystallographic anisotropy of higher order on the critical field of domain formation and the hysteresis loops of uniaxial magnets is investigated. It is shown that the critical field depends strongly on both the sign of K₁ and on the ratio of the magnitudes and signs of K₂/K₁ and K₃/K₁. On the basis of stability analysis for the free energy, hysteresis loops of uniaxial magnets as a function of K_i are calculated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 39–43, April, 1990.     

A connection between correlations and the order of bit-number cumulants

Bit-number cumulants have been introduced in earlier papers of the author and were shown to give an ordered system of stochastic measures for correlations between subsystems of a thermodynamic system. It will be shown that in case of the onset of small correlations between the subsystems the bit-number cumulant of ordern is influenced by no higher thann-tuplet correlations.     

The scaling of higher cumulants in a diffusion problem

The scaling properties of higher cumulants for a diffusion problem are examined by means of numerical calculations. The exponent for the higher cumulants are found to be less than that of the first cumulant but larger than that of the second one. The calculations can be used for describing quantum particle diffusion in a random time-dependent potential, domain wall diffusion in a 2D magnet, etc.     

Scaling properties of azimuthal anisotropy of mesons and baryons at RHIC

Detailed measurements of the azimuthal anisotropy (v ₂) for identified charged particles are reported as a function of transverse momentum (pT) and centrality for Au+Au collisions at $\sqrt {s_{NN} } = 200$ GeV. The measurements indicate clear evidence for eccentricity and particle flavor scaling over a broad range of centralities and transverse rapidity yT, indicating a hydrodynamical origin of the fine structure of azimuthal anisotropy at RHIC. The observed scaling supports the picture of a suddenly hadronizing (recombining) fluid of quarks. An apparent breaking of flavor scaling at relatively large values of yT points to an important change in the mechanism for particle emission.     

Azimuthal anisotropy of jet quenching at LHC

We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard partons in quark-gluon plasma, created initially in nuclear overlap zone in collisions with non-zero impact parameter. The calculations are performed for semi-central Pb-Pb collisions at LHC energy.     

On the neglecting of higher‐order cumulants in EXAFS data analysis

The cumulant expansion is one of the most powerful and useful methods for EXAFS data analysis, in which the higher‐order cumulants allow to consider deviations from a simple Gaussian distribution. In this work, analytical expressions have been derived to show the effects of neglecting higher‐order cumulants in EXAFS analysis by the ratio method. The errors in the best‐fitting procedure owing to the omission of the higher‐order cumulants, as well as of the coordination number, can be determined.     

Quasi-long-range order in the random anisotropy Heisenberg model

The random field and random anisotropy N-vector models are studied with the functional renormalization group in 4−ε dimensions. The random anisotropy Heisenberg (N=3) model has a phase with an infinite correlation length at low temperatures and weak disorder. The correlation function of the magnetization obeys a power law 〈m(r ₁)m(r ₂)〉∼|r ₁−r ₂|^{− 0.62ε}. The magnetic susceptibility diverges at low fields as χ∼H ^−1+0.15ε. In the random field N-vector model the correlation length is finite at arbitrarily weak disorder for any N>3. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 2, 130–135 (25 July 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Extracting anisotropy energy barrier distributions of nanomagnetic systems from magnetization/susceptibility measurements

Anisotropy barrier distributions of single domain particle systems are an important issue in the nanomagnetism and its applications. Different methods to extract the distribution from temperature, field, or time-dependent magnetization/susceptibility are reviewed and compared. A single domain particle system is measured to test the methods.     

On the incorporation of cubic and hexagonal interfacial energy anisotropy in phase field models using higher order tensor terms

In this paper, we show how to incorporate cubic and hexagonal anisotropies in interfacial energies in phase field models; this incorporation is achieved by including up to sixth rank tensor terms in the free energy expansion, assuming that the free energy is only a function of coarse-grained composition, its gradient, curvature and aberration. We derive the number of non-zero and independent components of these tensors. Further, by demanding that the resultant interfacial energy is positive definite for inclusion of each of the tensor terms individually, we identify the constraints imposed on the independent components of these tensors. The existing results in the invariant group theory literature can be used to simplify the process of construction of some (but not all) of the higher order tensors. Finally, we derive the relevant phase field evolution equations and describe some preliminary results from our 1D simulations.     

Ring and jet study on the azimuthal substructure of pions at CERN SPS energy

We have presented an investigation on the ring- and jet-like azimuthal angle substructures in the emission of secondary charged hadrons coming from ³²S–Ag/Br interactions at 200 A GeV/c. Nuclear photographic emulsion technique has been employed to collect the experimental data. The presence of such substructures, their average behaviour, their size, and their position of occurrence have been examined. The experimental results have also been compared with the results simulated by Monte-Carlo method. The analysis strongly indicates the presence of ring- and jet-like structures in the experimental distributions of particles beyond statistical noise. The experimental results are in good agreement with I M Dremin idea, that the phenomenon is similar to the emission of Cherenkov electromagnetic radiation.     

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 $p_\mathrm{T}$ and centrality dependencies of quadrangular flow $v_4$ , and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ flows.     

Extracting uniaxial anisotropy of ferromagnetic layer in exchange-biased system

Effective anisotropy of the ferromagnetic pinned layer of ferro(FM)-antiferromagnetic (AF)-coupled NiFe(FM)/FeMn(AF) exchange-biased system was investigated in a broad frequency range (100 MHz-5 GHz) using a complex permeability spectrum. The exchange bias and effective uniaxial anisotropy fields of the thin film have been computed theoretically using the Landau-Lifschitz-Gilbert (LLG) equation. From the measurements, uniaxial anisotropy of the pinned FM layer has been extracted to understand the nature of the exchange bias in the system. It is found that the uniaxial anisotropy field of NiFe layer when exchange biased with the AF layer increases from 5 to 15 Oe at different external magnetic fields.     

Visualization of the vortical structure of a circular jet excited by axial and azimuthal perturbations

The vortical structure of a circular water jet was investigated by a flow visualization technique. The jet was excited by axial and azimuthal perturbations to stabilize and enhance the large-scale axisymmetric and streamwise vortices. A laser fluorescent dye and a laser light sheet were used to visualize the vortical structure, and the whole view of the structure was captured by applying the Taylor hypothesis to the cross-sectional images and by scanning a laser light sheet in the streamwise direction. The visualized images reveal the details of the complicated structure of axisymmetric and streamwise vortices, and it is confirmed that the streamwise vortices have fundamental effect on the entrainment of ambient fluid. From the images, the length of jet boundary was calculated to estimate the mixing effect. The result suggests that the jet mixing is significantly increased by the break-down of the vortices enhanced by axial and azimuthal perturbations. We also discussed the jet diffusion effect in consideration of the jet widths obtained by velocity measurement. The result indicates that the vortical structure including streamwise vortices plays an important role to enhance diffusion.     

Probing TMDs through azimuthal distributions of pions inside a jet in hadronic collisions

The azimuthal distributions around the jet axis of leading pions produced in the jet fragmentation process in pp collisions are studied within the framework of the so-called generalized parton model. The observable leading-twist azimuthal asymmetries are estimated in kinematic configurations presently investigated at RHIC. It is shown how the main contributions coming from the Collins and Sivers effects can be disentangled. In addition, a test of the process dependence of the Sivers function is provided.