A study on the isolated photon production in nuclear collisions at the CERN-LHC energies

An analysis of prompt photon production in high energy nuclear collisions at the LHC is performed within the parton saturation picture taking into account the updated phenomenological color dipole models. Comparison between $\langle N_{coll}\rangle$ scaling for hard scattering in heavy-ion collisions and the $N_{part}$-scaling based on geometric scaling arguments has been done. The predictions are parameter free in the first case whereas a dependence on the constant of proportionality $\kappa$ between the number of participants and the nuclear saturation scale appears in the second case. This parameter has been analyzed in the prompt photon spectrum at small transverse momentum even though no fitting procedure was performed. Results are confronted with the measurements made by the ALICE, ATLAS, and CMS experiments in terms of photon transverse momentum at different rapidity bins. We show that the prompt photon production exhibits distinct scalings in $AA$ events associated to geometrical properties of the collision and can be properly addressed in the color dipole formalism. Based on the $N_{part}$-scaling, an analytical parametrization for the invariant cross section is provided and employed to predict the $x_T$-scaling in measurements. For $\kappa$ of order of unit the theoretical scaling curve correctly describes data in the range $x_T\leq 5\times 10^{-2}$.

Cumulative $${\pi}$$-Mesons in $${}^{{12}}{C}{+}{}^{{9}}$$Be-Interactions at 3.2 GeV/Nucleon

In the FRAGM experiment at the heavy-ion accelerator$$-$$accumulator complex ITEP$$-$$TWA, yields of cumulative charged $$\pi$$ mesons have been measured in a fragmentation of carbon ions with the energy of 3.2 GeV/nucleon on a beryllium target. The momentum spectra of $$\pi$$ mesons cover four orders of the invariant cross section magnitude. They demonstrate the exponential fall with increasing energy. The measured inverse slope parameter is compared with similar measurements in nucleon–nucleus interactions and ion–ion collisions at lower energies. The energy dependence of the ratio of the yields of negative to positive $$\pi$$ mesons is presented. This dependence is discussed in a connection with Coulomb and isotopic effects. The obtained data are compared with predictions of several ion–ion interaction models.

The Effect of Rise Angle of V-Hull Non Ballast Ship on Resistance Performance

In this paper a new concept in ship design was used to be alternative of ballast water system, to emerge that remedy the introduction of invasive marine species and the disadvantages of ballast water treatment systems.Thus, the hydrodynamic influences due to hull line variation of this kind of ships were studied, using the invariant cross-section area curve under the design draft to change the rise angle at bottom. Then numerical calculation was used to get the resistance and effective power at each angle. Two 3D models were constructed for 59000 DWT oil tankers and 35000 DWT bulk carriers, where the result of the bulk carrier was exposed.

The Resistance Performance Influences from Hull Line Variation of V-Shaped Non-Ballast Ship (NoBS)

As a New Concept in Ship Design to be Alternative of Ballast Water System, to Emerge that Remedy the Introduction of Invasive Marine Species and the Disadvantages of Ballast Water Treatment Systems. the Non-Ballast Ship has been Studied Abroad, but it is Rarely Mentioned in China. in this Paper, the Hydrodynamic Influences due to Hull Line Variation of this Kind of Ships were Studied, Using the Method of Invariant Cross-Section Area Curve under the Design Draft to Change the Rise Angle at Bottom. then by Using Numerical Calculation, get the Resistance and Effective Power at each Angle.

Correction for Classical Theory of Yarn Cross-Section Shape in Woven Fabric

The cross-section of yarn in plain woven fabric has always been viewed as an invariable shape by academe. However, with visualization technology, problems in the classical model are exposed based on traditional convex model, and when solving the problems with calculus, the rule of yarn cross-section deformation is found. The results show the diversity of yarn cross-section shape in both one-layer and multi-layer woven fabric, instead of unitarity, especially for warps weaving multi-layer wefts, whose convex cross-section alternates with concave one periodically in length. The results take exception to “invariant cross-section assumption” and have theoretical value and guidance for the real shape of yarns and the simulation of fabric appearance.

A-DEPENDENCE OF Z-SCALING

The A-dependence of z-scaling in inclusive hadron production in pA collisions at high transverse momenta is studied. The concept of z-scaling based on the fundamental principles of Nature such as self-similarity, locality, scale relativity and fractality reflecting the general features of particle interactions is applied for the description of processes of hadron production in pA collisions. The scaling function ψ is expressed via the invariant cross-section Ed3σ/dq3 and the average multiplicity density dN/dη of particles produced at pseudorapidity η=0 in the corresponding nucleon–nucleon interaction. The independence of the function ψ(z) on the center-of-mass energy [Formula: see text] for particle production near 90° in the NN c.m. system for different nuclei from D up to Pb is shown. The scale transformation z→az, ψ→a-1ψ is used to determine the A-dependence of the transformation parameter a. Based on the properties of z-scaling the dependence of the cross-sections for the π±, K±, and [Formula: see text] hadrons produced in pA collisions on transverse momentum q⊥ in the central region (η=0) at RHIC energies is predicted.