On Two-Ridge Structure in Two-Particle Azimuthal Correlations in Proton-Lead Collisions at Large Hadron Collider Energy

Two-particle azimuthal correlations are studied in the framework of a multisource thermal model. Each source is assumed to produce many particles. Each particle pair measured in final state is considered to be produced at two emission points (subsources) in a single or two sources. The first emission point corresponds to the production of “trigger” particle and the second one corresponds to that of “associated” particle. There are oscillations and other interactions between the two emission points. In the rest frame of the “associated” particle's emission point, the oscillations and other interactions cause the momentum of the “trigger” particle to depart from the original value. The modelling results are in agreement with the experimental data of proton-lead (p-Pb) collisions at <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><mrow><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt></mrow></math> = 5.02 TeV, one of the Large Hadron Collider energies, measured by the ALICE and ATLAS Collaborations

On Descriptions of Particle Transverse Momentum Spectra in High Energy Collisions

The transverse momentum spectra obtained in the frame of an isotropic emission source are compared in terms of Tsallis, Boltzmann, Fermi-Dirac, and Bose-Einstein distributions and the Tsallis forms of the latter three standard distributions. It is obtained that, at a given set of parameters, the standard distributions show a narrower shape than their Tsallis forms which result in wide and/or multicomponent spectra with the Tsallis distribution in between. A comparison among the temperatures obtained from the distributions is made with a possible relation to the Boltzmann temperature. An example of the angular distributions of projectile fragments in nuclear collisions is given

Comparing Multicomponent Erlang Distribution and Lévy Distribution of Particle Transverse Momentums

The transverse momentum spectrums of final-state products produced in nucleus-nucleus and proton-proton collisions at different center-of-mass energies are analyzed by using a multicomponent Erlang distribution and the Lévy distribution. The results calculated by the two models are found in most cases to be in agreement with experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The multicomponent Erlang distribution that resulted from a multisource thermal model seems to give a better description as compared with the Lévy distribution. The temperature parameters of interacting system corresponding to different types of final-state products are obtained. Light particles correspond to a low temperature emission, and heavy particles correspond to a high temperature emission. Extracted temperature from central collisions is higher than that from peripheral collisions

Transverse Momentum and Pseudorapidity Distributions of Charged Particles and Spatial Shapes of Interacting Events in Pb-Pb Collisions at 2.76 TeV

The transverse momentum and pseudorapidity distributions of charged particles produced in Pb-Pb collisions with different centrality intervals at center-of-mass energy per nucleon pair <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><msqrt><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>2.76</mn></math>  TeV have been analyzed by using the improved multisource thermal model in which the whole interacting system and then the sources are described by the Tsallis statistics. The modelling results are in agreement with experimental data of the ALICE Collaboration. The rapidity distributions of charged particles are obtained according to the extracted parameter values. The shapes of interacting events (the dispersion plots of charged particles) are given in the momentum, rapidity, velocity, and coordinate spaces. Meanwhile, the event shapes in different spaces consisted by different transverse quantities and longitudinal quantities are presented

Enhanced tensile ductility and strength of electrodeposited ultrafine-grained nickel with a desired bimodal microstructure

This work aims to use surfactant-assisted direct current electrodeposition technique to prepare four types of bimodal nickel, under different current densities. Bimodal Ni is obtained with different grain size and spatial distribution of CG and UFG areas showing a big disparity in mechanical properties. As a result of small population of coarse-grained surrounded by quite a lot of ultrafine-grained forming a unique shell-and-core bimodal structure, bimodal one present the best comprehensive mechanical properties with an ultrahigh tensile strength (similar to 847 MPa) and a considerable plastic strain (similar to 16.7%). Deformation initial, bimodal structures display more positive strain hardening to meaningful strains than unimodal structure of UFG and CG. Particularly bimodal one work-hardening rate is the highest thanks to its structure (UFG occupy 76.7% in total number fraction) and the distribution of growth twins. Growth twins in this article are referred to Sigma 3(111) coherent twins playing an important role in improving high strength, enhancing uniform plastic deformation ability

Double-Differential Production Cross Sections of Charged Pions in Charged Pion Induced Nuclear Reactions at High Momentums

The double-differential <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mrow><mi>π</mi></mrow><mrow><mo>±</mo></mrow></msup></mrow></math> production cross sections in interactions of charged pions on targets at high momentums are analyzed by using a multicomponent Erlang distribution which is obtained in the framework of a multisource thermal model. The calculated results are compared and found to be in agreement with the experimental data at the incident momentums of 3, 5, 8, and 12 GeV/c measured by the HARP Collaboration. It is found that the source contributions to the mean momentum of charged particles and to the distribution width of particle momentums decrease with increase of the emission angle, and the source number and temperature do not show an obvious dependence on the emission angle of the considered particle

B0 – B¯0 mixing in supersymmetry with gauged baryon and lepton numbers

We perform an analysis on B0 – B¯0 mixing in the extension of the minimal supersymmetric standard model where baryon and lepton numbers are local gauge symmetries (BLMSSM) by using the effective Hamiltonian method. And the constraint of a 125 GeV Higgs to the parameter space has also been considered. The numerical results indicate that the contributions of the extra particles can be sizeable in B0 – B¯0 mixing. For certain parameter sets, the theoretical prediction of mass differences ΔmB agrees with the current experimental result. Furthermore B0 – B¯0 mixing in the BLMSSM can preliminarily constrain the parameter space. With the development of more precise theoretical analysis and experimental determinations, the B0 – B¯0 mixing in the BLMSSM will have a clearer picture and the parameter space in this model will also be further constrained

Pseudorapidity Distribution of Charged Particles and Square Speed of Sound Parameter in <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mi>p</mi><mtext>-</mtext><mi>p</mi></math> or <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mi>p</mi><mtext>-</mtext><mover accent="true"><mrow><mi>p</mi></mrow><mo>-</mo></mover></math> Collisions over an Energy Range from 0.053 to 7 TeV

Pseudorapidity distributions of charged particles produced in proton-proton ( <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><mi>p</mi><mtext>-</mtext><mi>p</mi></math> ) or proton-antiproton ( <math id="M4" xmlns="http://www.w3.org/1998/Math/MathML"><mi>p</mi><mtext>-</mtext><mover accent="true"><mrow><mi>p</mi></mrow><mtext>-</mtext></mover></math> ) collisions over an energy range from 0.053 to 7 TeV are studied by using the four-component Landau hydrodynamic model. The results calculated by the model are in agreement with the experimental data of the UA5, PHOBOS, UA1, P238, CDF, ALICE, and CMS Collaborations which present orderly from low to high energies. According to the distribution widths of different components, the values and some features of square speed of sound parameter <math id="M5" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msubsup><mrow><mi>c</mi></mrow><mrow><mi>s</mi></mrow><mrow><mn>2</mn></mrow></msubsup></mrow></math> for “participant” and “spectator” quark components are obtained. It is shown that the speed of sound for “participant” quark components agrees approximately with that for “spectator” quark components in the error ranges. The present work is useful for studying nucleus-nucleus collisions in the related energy range