The recent measurements of the global polarization and vector meson spin alignment along the system orbital momentum in heavy ion collisions are briefly reviewed. A possible connection between the ...global polarization and the chiral anomalous effects is discussed along with possible experimental checks. Future directions, in particular those aimed on the detailed mapping of the vorticity fields, are outlined. The Blast Wave model is used for an estimate of the anisotropic flow effect on the vorticity component along the beam direction. We also point to a possibility of a circular pattern in the vorticity field in asymmetric, e.g. Cu+Au, central collisions.
We show that hadronization via quark coalescence enhances hadron elliptic flow at large p(perpendicular) relative to that of partons at the same transverse momentum. Therefore, compared to earlier ...results based on covariant parton transport theory, more moderate initial parton densities dN/deta(b=0) approximately 1500-3000 can explain the differential elliptic flow v(2)(p(perpendicular)) data for Au+Au reactions at sqrts=130 and 200A GeV from BNL RHIC. In addition, v(2)(p(perpendicular)) could saturate at about 50% higher values for baryons than for mesons. If strange quarks have weaker flow than light quarks, hadron v(2) at high p(perpendicular) decreases with relative strangeness content.
Narrow-linewidth lasers and optical frequency combs generated with mode-locked lasers have revolutionized optical frequency metrology. The advent of soliton Kerr frequency combs in compact ...crystalline or integrated ring optical microresonators has opened new horizons in academic research and industrial applications. These combs, as was naturally assumed, however, require narrow-linewidth, single-frequency pump lasers. We demonstrate that an ordinary cost-effective broadband Fabry–Pérot laser diode at the hundreds of milliwatts level, self-injection-locked to a microresonator, can be efficiently transformed to a powerful single-frequency, ultra-narrow-linewidth light source with further transformation to a coherent soliton comb oscillator. Our findings pave the way to the most compact and inexpensive highly coherent lasers, frequency comb sources, and comb-based devices for mass production.
We present a novel method allowing high-power single-frequency emission with sub-kHz linewidth from a compact multi-frequency diode laser locked to high-Q optical microresonator. Using high-Q MgF
...microresonator and multi-frequency diode laser operating at 1535 nm with the output power of 100 mW and an emission spectrum consisting of approximately 50 lines with MHz linewidth, we observed a spectrum collapse to a single line or several lines with a sub-kHz linewidth and output power power of 50 mW. The Bogatov effect predicted more than 30 years ago was observed and studied in the spectrum of the locked laser. For analysis of the considered effect, original theoretical model taking into account self-injection locking effect, mode competition and Bogatov asymmetric mode interaction was developed and numerical modeling was performed. All numerical results are in a good agreement with our experimental data. Accurate analytical estimations for the parameters critical for the considered effect were obtained. The proposed method may be applied for different types of diode lasers operating in different spectral ranges.
We discuss a specific model of elliptic flow fluctuations due to Gaussian fluctuations in the initial spatial x and y eccentricity components {〈(σy2−σx2)/(σx2+σy2)〉,〈2σxy/(σx2+σy2)〉}. We find that in ...this model v2{4}, elliptic flow determined from 4-particle cumulants, exactly equals the average flow value in the reaction plane coordinate system, 〈vRP〉, the relation which, in an approximate form, was found earlier by Bhalerao and Ollitrault in a more general analysis, but under the same assumption that v2 is proportional to the initial system eccentricity. We further show that in the Gaussian model all higher order cumulants are equal to v2{4}. Analysis of the distribution in the magnitude of the flow vector, the Q-distribution, reveals that it is totally defined by two parameters, v2{2}, the flow from 2-particle cumulants, and v2{4}, thus providing equivalent information compared to the method of cumulants. The flow obtained from the Q-distribution is again v2{4}=〈vRP〉.
At the very first stage of an ultra-relativistic nucleus–nucleus collision new particles are produced in individual nucleon–nucleon collisions. In the transverse plane, all particles from a single NN ...collision are initially located at the same position. The subsequent thermalization and transverse radial expansion of the system create strong position-momentum correlations and lead to characteristic rapidity, transverse momentum, and azimuthal correlations among the produced particles.
Adescription of architecture of real-time software and hardware platform “Digital Twin for Power System” is presented. The hardware of each platform level, as well as the composition of the software ...modules implemented at each level, is considered. The advantages of the modular construction of the platform for the implementation of various options for its use are described.
A quark interaction with topologically nontrivial gluonic fields, instantons and sphalerons, violates P and CP symmetry. In the strong magnetic field of a noncentral nuclear collision such ...interactions lead to the charge separation along the magnetic field, the so-called chiral magnetic effect (CME). Recent results from the STAR collaboration on charge dependent correlations are consistent with theoretical expectations for CME but may have contributions from other effects, which prevents definitive interpretation of the data. Here I propose to use central body-body U+U collisions to disentangle correlations due to CME from possible background correlations due to elliptic flow. Further, more quantitative studies can be performed with collision of isobaric beams.
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