arXiv subjects

Chengdong Han

Publications and source records attributed to Chengdong Han.

26 records · Page 2Linked to original sources

arXiv2021

Simulation of the neutron-tagged deep inelastic scattering at EicC

Measuring the pionic structure function is of high interests as it provides a new area for understanding the strong interaction among quarks and testing the QCD predictions. To this purpose, we investigate the feasibility and the expected impacts of a possible experiment on EicC. We show the simulation results on the statistical precision of an EicC measurement, based on the model of leading neutron tagged DIS process and the parton distribution functions of the pion from JAM18 global analysis. The simulation shows that at EicC, the kinematics cover $x_π$ range from 0.01 to 1, and $Q^2$ range from 1 GeV$^2$ to 50 GeV$^2$, within the acceptable statistical uncertainty. Assuming an integrated luminosity of 50 fb$^{-1}$, in the low-$Q^{2}$ region ($<10$ GeV$^2$), the MC data show that the suggested measurement in the whole $x_{\rmπ}$ range reaches very high precision ($<3$\%). To perform such an experiment, only the addition of a far-forward neutron calorimeter is needed.

hep-ph↗

arXiv2021

An Analysis of Parton Distribution Functions of the Pion and the Kaon with the Maximum Entropy Input

We present pion and kaon parton distribution functions from a global QCD analysis of the experimental data within the framework of dynamical parton model. We use the DGLAP equations with parton-parton recombination corrections and the valence input of uniform distribution which maximizes the information entropy. At our input scale $Q_0^2$, there are no sea quark and gluon distributions. All the sea quarks and gluons of the pion and the kaon are completely generated from the parton splitting processes. The mass-dependent parton splitting kernel is applied for the strange quark distribution in the kaon. The obtained valence quark and sea quark distributions at high $Q^{2}$ ($Q^2>5$ GeV$^2$) are compatible with the existed experimental measurements. Furthermore, the asymptotic behaviours of parton distribution functions at small and large $x$ have been studied for both the pion and the kaon. Lastly, the first three moments of parton distributions at high $Q^{2}$ scale are calculated, which are consistent with other theoretical predictions.

hep-ph↗

arXiv2021

Electron-Ion Collider in China

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of $\sim$80%) and protons (with a polarization of $\sim$70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2-3) $\times$ 10$^{33}$ cm$^{-2}$ s$^{-1}$. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC. The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies. This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.

nucl-ex↗

arXiv2019

Pion Valence Quark Distributions from Maximum Entropy Method

Valence quark distributions of pion at very low resolution scale $Q^{2}_0 \sim 0.1~GeV^2$ are deduced from a maximum entropy method, under the assumption that pion consists of only a valence quark and a valence anti-quark at such a low scale. Taking the obtained initial quark distributions as the nonperturbative input in the modified Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (with the GLR-MQ-ZRS corrections) evolution, the generated valence quark distribution functions at high $Q^2$ are consistent with the measured ones from a Drell-Yan experiment. The maximum entropy method is also applied to estimate the valence quark distributions at relatively higher $Q^2$ = 0.26 GeV$^{2}$. At this higher scale, other components (sea quarks and gluons) should be considered in order to match the experimental data. The first three moments of pion quark distributions at high $Q^2$ are calculated and compared with the other theoretical predictions.

hep-ph↗

arXiv2018

Gottfried sum rule from maximum entropy method quark distributions with DGLAP evolution and DGLAP evolution with GLR-MQ-ZRS corrections

A new method to test the valence quark distribution of nucleon obtained from the maximum entropy method using Gottfried sum rule by performing DGLAP equations with the GLR-MQ-ZRS corrections and original LO~/~NLO DGLAP equations are outlined. The test relies on a knowledge of the unpolarized electron-proton structure function $F_2^{ep}$ and electron-neutron structure function $F_2^{en}$ and the assumption that Bjorken scaling is satisfied. In this work, the original Gottfried summation value obtained by the integrals of the structure function at different Q$^{2}$ is in accordance with the theoretical value 1/3 under the premise of light-quark flavour symmetry of nucleon sea, whether it is the result from the dynamics evolution equations or the result from global QCD fits of PDFs. Finally, we present the summation value of the LO / NLO DGLAP global fits of PDFs under the premise of light-quark flavour asymmetry of nucleon sea. According to analysis the original Gottfried summation value with two evolution equations at different $Q^{2}$, we can know that the valence quark distributions of nucleon obtained by the maximum entropy method are effective and reliable.

hep-ph↗

arXiv2018

A Generalized Model for Light Transport in Scintillators

Transported light in the medium usually shows as an exponential decay tendency. In the DAMPE strip scintillators, however, the phenomenon of light attenuation as the hit position approaches the end of the scintillator can not be described by the simple exponential decay model. The spread angle of PMT relative to hit position is distance-dependent, so the larger the angle, the larger the proportion $η$ of emitted light to becomes the effective input light. We consider the contribution of the spread angle, and propose a generalized model: $f(x)=I_0η_{a}(x)e^{-x/λ}+I_0η_{b}(x)e^{-(2L-x)/λ}$. The model well describes the light attenuation in the scintillator, reducing the maximum deviation of the sample from the fit function from 29\% to below 2\%. Moreover, our model contains most of the traditional models, so the experimental data that traditional models can fit and our models fit well.

physics.ins-det↗

arXiv2017

Estimating proton radius and proportion of other non-perturbative components in the proton by the Maximum Entropy Method

In this paper, we apply the Maximum Entropy Method to estimate the proton radius and determine the valence quark distributions in the proton at extremely low resolution scale Q$^{2}_{0}$. Using the simplest functional form of the valence quark distribution and standard deviations of quark distribution functions in the estimation of the proton radius, we obtain a quadratic polynomial for the relationship between the proton radius and the momentum fraction of other non-perturbative components in the proton. The proton radii are approximately equal to the muonic hydrogen experimental result $r_p$ = 0.841~fm and the CODATA analysis $r_p$ = 0.877 fm when the other non-perturbative components account for 17.5\% and 22.3\% respectively. We propose $"ghost~~matter"$ to explain the difference in other non-perturbative components (4.8\%) that the electron can detect.

hep-ph↗

arXiv2015

IsoDAR Neutrino Experiment Simulation with Proton and Deuteron Beams

In this paper we consider high-intensity source of electron antineutrinos from the production and subsequent decay of 8Li. It opens a wide range of possible searches for beyond standard model physics via studies of the inverse beta decay interaction. In IsoDAR experiments Lithium 8 is a short lived beta emitter producing a high intensity anti-neutrinos, which is very suitable for making several important neutrino experiments. In this paper we used the GEANT4 program. to simulate neutrino production using proton and deuteron beams. We find that the neutrino production rate is about 3 times from deuteron beam than from proton beam in low energy region.

physics.ins-det↗