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Meng Ta-chung

Publications and source records attributed to Meng Ta-chung.

At least 19 recordsLinked to original sources
arXiv2005

Direct evidence for the validity of Hurst's empirical law in hadron production processes

We propose to use the rescaled range analysis to examine the records of rapidity-dependence of multiplicities in high-energy collision processes. We probe event by event the existence of global statistical dependence in the system of produced hadrons, and demonstrate the effectiveness of the above-mentioned statistical method by applying it to the cosmic-ray data of the JACEE collaboration, and by comparing the obtained results with other experimental results for similar reactions at accelerator and collider energies. We present experimental evidence for the validity of Hurst's empirical law, and the evidence for the existence of global statistical dependence, fractal dimension, and scaling behavior in such systems of hadronic matter. None of these features is directly related to the basis of the conventional physical picture. Hence, it is not clear whether (and if yes, how and why) these striking empirical regularities can be understood in terms of the conventional theory.

hep-ph↗
arXiv2004

Power-law behavior observed in $p_{T}$-distributions and its implications in relativistic heavy-ion collisions

Preconception-free analyses of the inclusive invariant transverse-momentum distribution data taken from the measurements of Au+Au collisions at $\sqrt{s_{NN}}=130$ GeV and $\sqrt{s_{NN}}=200$ GeV have been performed. It is observed that the distributions exhibit for $p_{T}\geq 2$ GeV/c remarkably good power-law behavior ($p_{T}$-scaling) with general regularities. This power-law behavior leads us in particular to recognize that the concept of centrality, albeit its simple appearance, is rather complex; its underlying geometrical structure has to be understood in terms of fractal dimensions. Experimental evidences and theoretical arguments are given which show that the observed striking features are mainly due to geometry and self-organized criticality. A simple model is proposed which approximately reproduces the above-mentioned data for the ``suppression'' without any adjustable parameter. Further heavy-ion collision experiments are suggested.

nucl-th↗
arXiv2001

Electron as Spatiotemporal Complexity due to Self-Organized Criticality

The electron, which has been pictured as an elementary particle ever since J.J. Thomson's e/m-measurement in 1897, and the relativistic motion of which is described by the Dirac equation, is discussed in the light of the recent progress made in Science of Complex Systems. Theoretical arguments and experimental evidences are presented which show that such an electron exhibits characteristic properties of spatiotemporal complexities due to Self-Organized Criticality (SOC). This implies in particular that, conceptually and logically, it is neither possible nor meaningful to identify such an object with an ordinary particle, which by definition is something that has a fixed mass (size), a fixed lifetime, and a fixed structure.

hep-ph↗
arXiv2001

Gluons in small-$x_B$ deep-inelastic scattering

The existing data obtained in deep-inelastic scattering (DIS) experiments in the kinematical region $x_B \approxle 10^{-2}$ and $Q^2 \ge 5 {GeV}^2$ are examined to gain further insight into the dynamics of interacting gluons. It is shown that not only the regularities observed in diffractive scattering and those found in large-transverse-momentum jet production, but also the striking features of the structure function $F_2(x_B,Q^2)$ observed in normal DIS-events in this kinematical region can be understood as direct consequences of self-organized criticality. The results explicitly demonstrate the usefulness of concepts and methods of Complex Sciences in understanding the various striking features observed in high-energy collision processes in which ``soft'' gluons play the dominating role.

hep-ph↗
arXiv2000

Criticality in quark-gluon systems far beyond thermal and chemical equilibrium

Experimental evidence and theoretical arguments for the existence of self-organized criticality in systems of gluons and quarks are presented. It is observed that the existing data for high-transverse-momentum jet-production exhibit striking regularities; and it is shown that, together with first-principle considerations, such regularities can be used, not only to probe the possible compositness of quarks, but also to obtain {\em direct evidence} for, or against, the existence of critical temperature and/or critical chemical potential in quark-gluon systems when hadrons are squeezed together.

hep-ph↗
arXiv1999

Formation of color-singlet gluon-clusters and inelastic diffractive scattering

This is the extensive follow-up report of a recent Letter in which the existence of self-organized criticality (SOC) in systems of interacting soft gluons is proposed, and its consequences for inelastic diffractive scattering processes are discussed. It is pointed out, that color-singlet gluon-clusters can be formed in hadrons as a consequence of SOC in systems of interacting soft gluons, and that the properties of such spatiotemporal complexities can be probed experimentally by examing inelastic diffractive scattering. Theoretical arguments and experimental evidences supporting the proposed picture are presented --- together with the result of a systematic analysis of the existing data for inelastic diffractive scattering processes performed at different incident energies, and/or by using different beam-particles. It is shown in particular that the size- and the lifetime-distributions of such gluon-clusters can be directly extracted from the data, and the obtained results exhibit universal power-law behaviors --- in accordance with the expected SOC-fingerprints. As further consequences of SOC in systems of interacting soft gluons, the $t$-dependence and the $(M_x^2/s)$-dependence of the double differential cross-sections for inelastic diffractive scattering off proton-target are discussed. Here $t$ stands for the four-momentum-transfer squared, $M_x$ for the missing mass, and $\sqrt{s}$ for the total c.m.s. energy. It is shown, that the space-time properties of the color-singlet gluon-clusters due to SOC, discussed above, lead to simple analytical formulae for $d^2σ/dt d(M_x^2/s)$ and for $dσ/dt$, and that the obtained results are in good agreement with the existing data. Further experiments are suggested.

hep-ph↗
arXiv1999

Inelastic diffraction and meson radii

It is shown that meson radii can be extracted from diffractive scattering experiments of the type: $m+p\to m + X$, where p stands for the target proton, and m for the incident charged meson $π^+$, $π^-$, $K^+$, or $K^-$. The basis of the method used to perform this extraction is the QCD-based SOC-picture for inelastic diffraction in high-energy hadron-hadron and lepton-hadron collisions proposed in a recent Letter. The obtained results for pion and kaon charge radii are compared with those determined in meson form factor measurements.

hep-ph↗
arXiv1999

Formation of color-singlet gluon-clusters and inelastic diffractive scattering. Part I: Theoretical arguments and experimental indications for self-organized criticality (SOC) in systems of interacting soft gluons

It is proposed, that color-singlet gluon-clusters can be formed in hadrons as a consequence of self-organized criticality (SOC) in systems of interacting soft gluons, and that the properties of such spatiotemporal complexities can be probed experimentally by examing inelastic diffractive scattering. Theoretical arguments and experimental evidences supporting the proposed picture are presented --- together with the result of a systematic analysis of the existing data for inelastic diffractive scattering processes performed at different incident energies, and/or by using different beam-particles. It is shown that the size- and the lifetime-distributions of such gluon-clusters can be directly extracted from the data, and the obtained results exhibit universal power-law behaviors --- in accordance with the expected SOC-fingerprints.

hep-ph↗
arXiv1999

Formation of color-singlet gluon-clusters and inelastic diffractive scattering. Part II: Derivation of the $t$- and $M_x^2/s$-dependence of cross-sections in the SOC-approach

The $t$-dependence and the $(M_x^2/s)$-dependence of the double differential cross-sections for inelastic diffractive scattering off proton-target are discussed. Here $t$ stands for the four-momentum-transfer squared, $M_x$ for the missing mass, and $\sqrt{s}$ for the total c.m.s. energy. It is shown, that the space-time properties of the color-singlet gluon-clusters due to SOC, discussed in Part I, lead to simple analytical formulae for $d^2σ/dt d(M_x^2/s)$ and for $dσ/dt$, and that the obtained results are in good agreement with the existing data. Further experiments are suggested.

hep-ph↗
arXiv1999

Inelastic diffraction and color-singlet gluon-clusters in high-energy hadron-hadron and lepton-hadron collisions

It is proposed, that ``the colorless objects'' which manifest themselves in large-rapidity-gap events are color-singlet gluon-clusters due to self-organized criticality (SOC), and that optical-geometrical concepts and methods are useful in examing the space-time properties of such objects. A simple analytical expression for the $t$-dependence of the inelastic single diffractive cross section $dσ/dt$ ($t$ is the four-momentum transfer squared) is derived. Comparison with the existing data and predictions for future experiments are presented. The main differences and similarities between the SOC-approach and the ``Partons in the Pomeron (Pomeron and Reggeon)''-approach are discussed.

hep-ph↗
arXiv1997

What can the final state particles in diffractive lepton-nucleon scattering tell us?

The colorless objects(s) in diffractive lepton-nucleon scattering in the small-$x_B$ region can be probed by examing the final state particles in such processes: (A) Perform multiplicity and/or energy factorial moment analyses, and check especially the $x_B$- and $Q^2$-dependence of the intermittency-indices. (B) Examine the diffractive structure function $F_2^{D(3)}(β,Q^2;x_P)$ as function of $x_P$ for different $β$ and $Q^2$. It is shown that such analyses and measurements can yield useful information on the hadronization process and on the intrinsic properties of the colorless objects. In particular, the observation of power-law distributions of $F_2^{D(3)}(β,Q^2;x_P)$ with respect to $x_P$ and with respect to $x_B$ --- independent of $β$ and $Q^2$-values may be considered as strong indication for the existence of self-organized criticality in gluon-cluster formation processes.

hep-ph↗
arXiv1997

Probing the exchanged object(s) in diffractive scattering

The reaction mechanisms of the following proton diffractive scattering processes are studied and compared with one another: $γ^* p\to Vp,γ^* p\to Xp, pp\to (ΛK^+)p$ and $pA\to ΛK^+A$ (Here, $γ^*$ stands for the space-like photon in inelastic electron-proton scattering, $V$ for the vector mesons $ρ,ω,ϕ,J/ψ$, and $A$ for a target nucleus.) It is shown that, by taking parity, and C--parity conservation into account, the existing data for these reactions strongly suggest the following: A considerable part of the objects exchanged between projectile and target in the above-mentioned processes are virtual quark-antiquark pairs in color-singlet states with $J^{PC}=0^{-+}$, $I^G=0^+$, where $J$ stands for total angular momentum, $I$ for isospin, $P$, $C$ and $G$ stand for parity, C-parity and G-parity respectively. Such quark-antiquark pairs are created by soft-gluon interactions. New experiments are suggested; and predictions for such experiments are made.

hep-ph↗
arXiv1996

Colorless and colored gluon-clusters in nucleon?

It is suggested that virtual gluon-clusters exist in nucleon, and that such colorless and colored objects manifest themselves in the small $x_B$ region of inelastic lepton-nucleon scattering processes. The relationship between the space-time properties of such clusters and the striking features observed in these scattering processes is discussed. A phase-space model is used to show how quantitative results can be obtained in such an approach. The results of this model-calculation are in reasonable agreement with the existing data. Further experiments are suggested.

hep-ph↗
arXiv1996

Probing dissociation of space-like photons in deep-inelastic lepton-nucleon scattering

It is shown that the hadronic dissociation of space-like $(Q^2>0)$ photons can be directly probed by performing measurements in the fragmentation region of transversely polarized and unpolarized proton beams at the electron-proton collider HERA. Measurements of momentum-distributions in the photon-fragmentation region in normal and in LRG (large rapidity gap) events are also suggested --- especially when the scattered proton or neutron in the proton-beam direction is tagged. It is pointed out that such distributions can yield useful information on the mechanisms of hadronic fragmentation in general, and answer the following questions in particular: Is the well-known hypothesis of limiting fragmentation (HFL) valid in color-exchange, in flavor-exchange, or only in vacuum-quantum-number-exchange processes ?

hep-ph↗