Energy Dependence of String Fragmentation Function and Ф Meson Production

The meson productions in Au+Au and/or Pb+Pb collisions at AGS, SPS, RHIC, and LHC energies have been studied systematically with a hadron and string cascade model LUCIAE. After considering the energy dependence of the model parameter α in string fragmentation function and adjusting it to the experimental data of charged multiplicity to a certain extent, the model predictions for meson yield, rapidity, and transverse mass distributions are compatible with the experimental data at AGS, SPS and RHIC energies. A calculation for Pb+Pb collisions at LHC energy is given as well. The obtained fractional variable in string fragmentation function shows a saturation in energy dependence. It is discussed that the saturation of fractional variable in string fragmentation function might be a qualitative representation of the energy dependence of nuclear transparency.

D^(*) jet fragmentation function paradox and combination mechanism

In the framework of the perturbative Quantum Chromodynamics factorization,the production of a hadron includes contributions from fragmentation as well as combination,with the latter being of higher twist.In particular,the heavy meson production can be via the combination of a heavy quark with a light one,and the cross section can be factorized to be the convolution of the combination matrix element,the light quark distribution function,and the hard partonic sub-cross section of the heavy quark production.The partonic distribution and the combination matrix element are functions of a scaling variable,respectively,which is the momentum fraction of the corresponding quark with respect to the heavy meson.We studied the D^(*±)production in jet via combination in pp collision at the LHC.The total result is comparable with the experimental data.The combination matrix elements can be further studied in various hadron production processes.

FRAGMENTATION FUNCTIONS IN e^+e^-,ep AND pp COLLISIONS

Revised August 2013 by O. Biebel （Ludwig-Maximilians-Universitat Munich, Germany）, D. de Florian （Dep. de Ffsica, FCEyN-UBA, Buenos Aires, Argentina）, D. Milstead （Fysikum, Stockholms Universitet, Sweden）, and A. Vogt （Dep. of Mathematical Sciences, University of Liverpool, UK）.

Relativistic correction to gluon fragmentation function into pseudoscalar quarkonium

Inspired by the recent measurements of the ηc meson production at LHC experiments, we investigate the relativistic correction effect for the fragmentation functions of gluon/charm quark fragmenting into ηc, which constitute the crucial nonperturbative element for the ηc production at high pT. Employing three distinct methods,we calculate the next-to-leading-order（NLO） relativistic correction to g →ηc fragmentation function in the NRQCD factorization framework, as well as verifying the existing NLO result for the c →ηc fragmentation function. We also study the evolution behavior of these fragmentation functions with the aid of the DGLAP equation.

A comparative study on the application of various artificial neural networks to simultaneous prediction of rock fragmentation and backbreak

In blasting operation,the aim is to achieve proper fragmentation and to avoid undesirable events such as backbreak.Therefore,predicting rock fragmentation and backbreak is very important to arrive at a technically and economically successful outcome.Since many parameters affect the blasting results in a complicated mechanism,employment of robust methods such as artificial neural network may be very useful.In this regard,this paper attends to simultaneous prediction of rock fragmentation and backbreak in the blasting operation of Tehran Cement Company limestone mines in Iran.Back propagation neural network（BPNN） and radial basis function neural network（RBFNN） are adopted for the simulation.Also,regression analysis is performed between independent and dependent variables.For the BPNN modeling,a network with architecture 6-10-2 is found to be optimum whereas for the RBFNN,architecture 636-2 with spread factor of 0.79 provides maximum prediction aptitude.Performance comparison of the developed models is fulfilled using value account for（VAF）,root mean square error（RMSE）,determination coefficient（R2） and maximum relative error（MRE）.As such,it is observed that the BPNN model is the most preferable model providing maximum accuracy and minimum error.Also,sensitivity analysis shows that inputs burden and stemming are the most effective parameters on the outputs fragmentation and backbreak,respectively.On the other hand,for both of the outputs,specific charge is the least effective parameter.

Lambda polarization at the Electron-ion collider in China

Lambda polarization can be measured through its self-analyzing weak decay, making it an ideal candidate for studying spin effects in high-energy scattering. In lepton-nucleon deep inelastic scattering(DIS), Lambda polarization measurements can probe polarized parton distribution functions(PDFs) and polarized fragmentation functions(FFs). One of the most promising facilities for high-energy nuclear physics research is the proposed Electron-ion collider in China(EicC). As a next-generation facility, EicC is set to advance our understanding of nuclear physics to new heights. In this article, we study the Lambda production in electron-proton collisions at the EicC energy, in particular the reconstruction of Lambda based on the performance of the designed EicC detector. In addition, taking spontaneous transverse polarization as an example, we provide a theoretical prediction with a statistical projection based on one month of EicC data, offering valuable insights into future research prospects.

Evolution of Shower Parton Distributions in a Jet from Quark Recombination Model

The evolution of shower parton distributions in a jet is investigated in the framework of a quark recombination model. The distributions are parameterized and the Q^2 dependence of the parameters is given by polynomials of In Q^2 for a wide range of Q^2

Next-to-leading-order QCD corrections to gluon fragmentation into ^(1)S_(0)^((1.8)) quarkonia

Within the NRQCD factorization framework,we compute the next-to-leading-order QCD corrections to the gluon fragmentation into the ^(1)S_(0)^((1.8)) Fock components of a quarkonium,at the lowest order in velocity expan-sion.We follow the operator definition of the fragmentation function advanced by Collins and Soper.The key tech-nique underpinning our calculation is the sector decomposition method widely used in the area of multi-loop compu-tation.It is found that the NLO QCD corrections have significant effects,and qualitatively modify the profiles of the corresponding leading-order fragmentation functions.

Charmed-Hadron Production in Υ(1S) Semi-inclusive Decay

In the framework of the NRQCD factorization formalism,we calculate the decay rate for the process Υ(1 S) → ccgg to the next-to-leading order(NLO) in the relative velocity v of the b quark in the bottomonium rest frame.We also study the momentum distributions of the charm quark and the charmed-hadron in the decay.The momentum distribution of the charmed-hadron is obtained by convolving the charm quark momentum distribution with a fragmentation function of the charm quark into the hadron.In addition,we fit the nonperturbative NRQCD matrix element v 2 Υ through comparing the theoretical prediction with the measurement from the BaBar collaboration for the decay rate of Υ(1 S) → D + X.In return,taking this matrix element as an input parameter,we predict the decay rates as well as the momentum distributions for a collection of charmed-hadrons in the process Υ(1S) → ccgg → hX.

Three-dimensional imaging of the nucleon and semi-inclusive high-energy reactions

We present a short overview of studies of the transverse-momentum-dependent parton distribution functions of the nucleon. The aim of such studies is to provide three-dimensional imaging of the nucleon and a comprehensive description of semi-inclusive high-energy reactions. By summarizing what we have done in constructing the theoretical framework for inclusive deep inelastic lepton-nucleon scattering and one-dimensional imaging of the nucleon, we try to sketch out an outline of what we need to do to construct such a comprehensive theoretical framework for semi-inclusive processes in terms of three-dimensional gauge-invariant patton distributions. Next, we present an overview of what we have already achieved, with an emphasis on the theoretical framework for semi-inclusive reactions in leading-order perturbative quantum chromodynamics but with leading and higher twist contributions. We summarize in particular the results for the differential cross section and azimuthal spin asymmetries in terms of the gauge-invariant transverse-momentum-dependent parton distribution functions. We also briefly summarize the available experimental results on semi-inclusive reactions and the parameterizations of transverse-momentum-dependent parton distributions extracted from them and present an outlook for future studies.