Chou-Yang Model Research Articles

Forward–backward multiplicity distribution with the Chou–Yang model for pp collisions at s = 0.9, 7 and 8 TeV from the CMS experiment

In this paper, a Chou–Yang-type multiplicity distribution comprising a total multiplicity component and a binomial asymmetry component is used to describe charged hadron multiplicity data at [Formula: see text] = 0.9, 7 and 8 TeV from the CMS experiment at CERN. The data was obtained and processed from the CERN Open Data Portal. For the total multiplicity component, it was found that a weighted superposition of a Negative Binomial Distribution (NBD) and a Furry–Yule Distribution (FYD) is able to describe the shoulder-like structure characteristic of Koba–Nielsen–Olesen (KNO) scaling violation well. The mean cluster size produced from collisions was also found to increase with collision energy. A prediction is given for pp collisions at [Formula: see text] = 14 TeV.

Realistic scattering of puffy dark matter

If dark matter has a finite size, the intrinsic interaction responsible for the structure formation is inevitable from the perspective of dark matter self-scattering. To describe the circumstance in which the binding force realizes the finite size dark protons, we first use the Eikonal approximation to simplify the convoluted scattering between dark protons into the case at the $t=0$ limit. The Chou-Yang model is then introduced to reduce the number of input parameters to one based on the simplicity and analyticity principle. A new definition of velocity dependence and the corresponding implications on the small cosmological structures from Chou-Yang dark protons are shown clearly. Even though the parameter space is not fully covered, the numerical findings show that the amplitude coefficient can alter the self-scattering cross-section, allowing us to recover the excluded parameter space without using binding force. Finally, we demonstrate that the correct relic density from thermal freeze-out production prefers super heavy dark protons.

Prediction of Rms Charge Radius of Proton Using Proton–Proton Elastic Scattering Data at TeV

Using proton–proton elastic scattering data at TeV and squared four-momentum transfer 0.36 < -t < 0.76 (GeV/c)2 for 13 σBeam distance and 0.07 < -t < 0.46 (GeV/c)2 for 4.3 σBeam distance, form factor of proton is predicted. Simplest version of Chou–Yang model is employed to extract the form factor by fitting experimental data of differential cross section from TOTEM experiment (for 13σBeamand 4.3 σBeam distance) to a single Gaussian. Root mean square (rms) charge radius of proton is calculated using this form factor. It is found to be equal to 0.91 fm and 0.90 fm respectively. Which is in good agreement with experimental data and theoretically predicted values.

Prediction of rms charge radius of proton using proton-proton elastic scattering data at TeV

Using proton–proton elastic scattering data at TeV and squared four-momentum transfer 0.36 < -t < 0.76 (GeV/c)2 for 13 σBeam distance and 0.07 < -t < 0.46 (GeV/c)2 for 4.3 σBeam distance, form factor of proton is predicted. Simplest version of Chou–Yang model is employed to extract the form factor by fitting experimental data of differential cross section from TOTEM experiment (for 13σBeamand 4.3 σBeam distance) to a single Gaussian. Root mean square (rms) charge radius of proton is calculated using this form factor. It is found to be equal to 0.91 fm and 0.90 fm respectively. Which is in good agreement with experimental data and theoretically predicted values.

Variation in rms charge radii of deuteron and helium nuclei with s\sqrt s

Abstract By considering energy-dependent form factors extracted from generalized Chou–Yang model, root mean square (rms) charge radii of deuteron and helium nuclei (alpha) are predicted at different values of center of mass energy which are in good agreement with theoretical predictions and experimental results. The rms radius is inversely proportional to mass of nuclei. Besides, the relationship between radii and energy are also derived.

Form Factor of Proton Predicted Using the Data of ppbar Elastic Scattering at $$\boldsymbol{\sqrt{s}=1.96}$$ eV

Based on the behavior of elastic scattering of proton and anti-proton at $$\sqrt{s}=1.96$$ TeV for squared four-momentum transfer $$0.26<{-}t<1.2($$ GeV $$/c)^{2}$$ , form factor of proton is predicted. Simplest version of Chou–Yang model is employed for extracting this form factor by fitting experimental data of differential cross section from D0 experiment to a single Gaussian. Root mean square (rms) matter radius of proton is calculated using this form factor. It is found to be equal to 0.89 fm. Which is in good agreement with experimental data and theoretically predicted values from other models.

Generalized Chou-Yang Model and Hadronic Radii

Generalized Chou-Yang model (GCYM) predicts electromagnetic form factors of several hadrons with varying magnitude of strangeness. By using these form factors, the root mean square (RMS) radii of the hadrons such as (π, p, ϕ, Λ, Σ+, Σ−and Ω−)are computed. It is found that there is consistency among the predicted RMS radii of pion and proton by GCYM (and other models) and experimental results. For all hadrons experimental results are not available. Also we find that results of GCYM and from other models are somewhat inconsistent for hadrons other than pion and proton. Though GCYM and other models do not agree for most of the hadrons but they have one similarity that the computed RMS radii seem decreasing with the increase in the strangeness level, separately for mesons as well as for baryons. The experimental results of hadrons other than pion and proton are needed to check the suitability of GCYM and other models as well as in probing the trend of decreasing radii with increase in strangeness content.

Predictions of the Chou–Yang Model for p-p Scattering at TeV

At low four-momentum transfer squared 0.02 < −t < 0.2 (GeV/c)2, we use the Chou–Yang model to predict the form factor of protons from proton–proton elastic scattering at center-of-mass energy TeV. By fitting differential cross-sectional data from the TOTEM experiment to a single Gaussian, the form factor is extracted. We use this form factor to find the rms matter radius of the proton to be 0.88 fm, which is in good agreement with the experimental data and the theoretically predicted values of the rms radius.

Chou-Yang Model for Forward-Backward Multiplicity Correlations at 7 TeV using Generalized Multiplicity Distribution.

The basis of the Chou-Yang model is made up of a stochastic and non-stochastic distribution and has been successful in describing forward-backward multiplicities.[1] This project examines data drawn from CERN’s 7 TeV run where we revist the Chou-Yang model’s components. It also approaches phenomenological descriptions for cluster sizes from forward-backward multiplicaity correlation strength by the E735 collaboration.[6] For the stochastic binomial component, it examines the variance of the charge asymmetry parameter z with regards to fixed total charged multiplicities n. The fitting of the Generalized Multiplicity distribution along with the linear least square fitting of the forward backward multiplicity is analysed. The parameters for the Generalized Multiplicity Distribution is presented along with an investigation on the cluster size r.[3] This serves as an extention to the work done by W.Y Wang’sWeighted GMD model at7TeV, however the nonweighted GMD model is used here.[7]

Reexamination of Cosmic‐Ray Composition around 1018eV from Fly's Eye Data

The cosmic-ray composition around 1018 eV is reexamined using the Chou-Yang model for the simulation of air showers and comparing with Fly's Eye data. This model is quite different from models previously used. Using this model leads to the same conclusion that the primary cosmic-ray composition gets lighter in the region from 3 × 1017 eV to 1019 eV. This conclusion of a changing composition is not sensitive to the choice of model because it results from the measured elongation rate being greater than that predicted for a constant composition by any reasonable model that can account for the measured depths of shower maxima at the Fly's Eye threshold energy. That constraint on elongation rate for a constant composition also implies that the increased rate of energy dissipation that appears in hadron-nucleus interactions near 1014 eV may continue up to the region of 1019 eV.

Anisotropy Function for Proton-Proton Elastic Scattering

By using the generalized Chou-Yang model and the experimental data on pp elastic scattering at 53 GeV, the anisotropy function which reflects the non-isotropic nature of elastic scattering is computed for the reaction pp →pp.

High energy predictions for ¯pp andpp elastic scattering and total cross sections

Predictions for thes behavior at high energies are made for¯pp andpp: the differential elastic scattering cross section dσ/dt vs.t, the squared 4-momentum transfer; the total elastic cross sectionσel; the nuclear slope parameterB; the curvature parameterC; ϱ, the ratio of the real to the imaginary portion of the forward scattering amplitude; and the total cross sectionσtot. A hybrid approach is employed in order to gain reliable predictions. The energy dependence ofϱ andσtot is fixed by fittingpp and¯pp experimental data forϱ andσtot from 15 GeV toS¯ppS energies, using analytic amplitudes. The other quantities are found using the Chou-Yang model, where the total, cross section is fixed from the fit.

Chou-Yang Model and Pion-Nucleus Elastic Scattering at High Energies

The Chou-Yang model has been used to explain, in the diffraction peak region, the differential cross section and the slope parameter for the pion-deuteron and the pionhelium elastic scattering at high energies.

Description of diffraction scattering on nuclei at all momentum transfers

The Glauber model, assumed valid for low momentum transfersq2→0, combines with the Chou-Yang model, assumed valid forq2→∞, to provide a good description of elastic diffraction scattering on nuclei at all momentum transfers. Comparison is with data on the processes αN→αN, N≡α, d,3He.

GENERALIZED CHOU-YANG MODEL AND MESON-PROTON ELASTIC SCATTERING AT HIGH ENERGIES

The various characteristics of meson-proton elastic scattering at high energies are explained by using the generalized Chou-Yang model which takes into consideration the anisotropic scattering of objects constituting pions(kaons) and protons. A new parametrization of the proton form factor consistent with the recent experimental data is proposed. It is then shown that all the data for meson-proton elastic scattering at 200 and 250 GeV/c are in agreement with theoretical computations. The physical picture of generalized Chou-Yang model which is based on multiple scattering theory is given in detail.

Hyperon-Neutron Elastic Scattering

It is shown that the Chou-Yang model can be extended to hyperon-neutron elastic reactions at high energies by assuming that the hadronic form factor of neutron is proportional to its magnetic form factor. It is also predicted that the scaling of magnetic form factor of neutron with charge as well as magnetic form factors of proton implies that the differential cross sections of corresponding hyperon-proton and hyperon-neutron reactions should be equal.

Energy fraction of the central region in the Chou-Yang model.

For the energy fraction of the central region in the Chou-Yang model we investigate dependencies on the total center-of-mass energy, multiplicity of charged particles, partition temperature, and average transverse momentum. Upper and lower bounds are obtained for the energy fraction. It is shown that the energy fraction approaches zero in the high-energy limit if the partition temperature is given by the empirical formula obtained through the analysis of experimental data of the pseudorapidity distribution via the Chou-Yang model. We examine the connection with the inelasticity distribution in hadron-hadron collision derived by Fowler and collaborators.

Implications of the Chou-Yang model fore+e−→hh¯

Analyses of ${P}_{\ensuremath{\perp}}$ and x,z distributions of inclusive ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}hh\ifmmode\bar\else\textasciimacron\fi{} from experiments at the SLAC storage ring PEP at 29 GeV confirm that there is only one temperature T=196\ifmmode\pm\else\textpm\fi{}7 MeV of ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation for various hadrons, as predicted by Chou and Yang. It is found that T\ensuremath{\propto}${E}^{1/4}$ according to the TASSO data; its relationship with the impact parameter b sets a lower limit (for b=0) ${T}_{0}$\ensuremath{\sim}106 MeV related to the effective light-quark mass ${m}_{q}$=3,${T}_{0}$\ensuremath{\simeq}318 MeV. Hadron multiplicities from PEP experiments, covering \ensuremath{\sim}3 orders of magnitude, are accounted for by a semiempirical formula derived from the Boltzmann factor with quark contents and a unique temperature T=196 MeV for all hadrons under investigation.

High energy limit of the energy fraction of the central region in the Chou-Yang model

The high energy behavior of the energy fraction of the central region in the Chou-Yang model is investigated. Bounds are obtained for the energy fraction. If the partition temperature is given by the empirical formula obtained via the analysis of experimental data for the pseudorapidity distribution, the energy fraction vanishes in the high energy limit. The connection between this result and the inelasticity distribution of Fowler et al. is discussed.

Anisotropy function for pion-proton elastic scattering

By using the generalised Chou-Yang model and the experimental data on pi -p elastic scattering at 200 GeV/c, the anisotropic function which reflects the non-isotropic nature of elastic scattering is compared for the reaction pi -p to pi -p.