31399287
From constituent quark to current quark: Origin of the European Muon Collaboration effect.
We have shown the predictions of the constituent quark model for nuclei are consistent with the New Muon Collaboration data in the {ital x}, {ital Q}{sup 2}, and {ital A} dependences of the European Muon Collaboration effect.
124556870
A New Effect in the QCD Fusion of Nuclear Partons
The parton fusion in nucleus at the leading order of recombination is investigated based on perturbative QCD. We compute various cut diagrams including the nuclear parton fusion, and find that the parton-fusion effects depend on the nuclear QCD structure.
124473583
Partonic Structure of the Pomeron in the Modified GLR Equation
The gluon recombination effect in the pomeron is studied by using the modified Gribov–Levin–Ryskin evolution equation. We find that the measured parton distributions in the pomeron can be generated dynamically from a purely gluonic input on assuming a small size for the pomeron.
18244927
Nuclear Shadowing and Antishadowing in a Unitarized BFKL Equation
The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation. The Q2and x-variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution. In particular, the asymptotical behavior of the unintegrated gluon distribution near the saturation limit in nuclear targets is studied. Our results in the nuclear targets are insensitive to the input distributions if the parameters are fixed by the data of a free proton. PACS numbers: 13.60.Hb; 12.38.Bx. keywords: nuclear shadowing and antishadowing; unintegrated gluon distribution in nuclei; QCD evolution equation Supported by National Natural Science Foundation of China 10135060, 10475028 and 10205004. Corresponding author, E-mail: weizhu @mail.ecnu.edu.cn
119716730
A twist-4 effect in the parton evolution processes
Recently, a research group reported that they can fit the F2 data well by using the Altarelli-Parisi evolution equation with a valence-like initial gluon distribution, which means that we need not consider the high twist effects in the proton. In this letter, we point out that their valence-like initial gluon distribution is unreasonable for the proton structure function. With the reasonable initial distributions, we find that the high twist corrections to the Altarelli-Parisi evolution equation is necessary.
122365434
Bag skin effect for Friedberg-Lee model
Importance of the bag skin effect to determine the parameters of the Friedberg-Lee model is pointed out. The European Muon Collaboration (EMC) effect regarded as a bag skin effect can be used to determine the parameters of this model.
33115967
Upper limit to the diffuse cosmic ultrahigh-energy gamma spectrum.
An upper limit to the diffuse cosmic ultrahigh-energy (UHE) gamma-spectrum from 5 TeV up to 1 PeV is inferred from data on the spectrum of the electromagnetic component of secondary cosmic rays recorded by emulsion-chamber experiments at various atmospheric depths. Our Monte Carlo simulation of the atmospheric propagation and interaction of the photons and protons with primary energies of (5 x 10(12))-10(15) eV shows that the intensity of uncorrelated gamma events with visible energies E-gamma = 5-100 TeV observed in emulsion-chamber experiments is sensitive to the diffuse cosmic UHE gamma-rays at the level of approximately 10(-3) compared to primary cosmic rays in the same energy region. We also discuss the relevance of the UHE gamma-spectrum to topics such as diffuse photons as by-products of the energy loss of extragalactic cosmic rays interacting with the cosmic 2.7 K background radiation, direct photons as a result of possible new production mechanisms, and photons as products of radiative decay of unstable cosmological relic neutrinos of mass approximately 5 TeV-1 PeV.
40623558
High Energy Processes in Clusters of Galaxies and the Origin of Cosmic Rays.
We test the hypothesis of a universal cosmic ray intensity by calculating the secondary electron or positron production in the hadronic interactions of cosmic ray nuclei with intergalactic gas within clusters of galaxies. We find that the spectral characteristics of the radio synchrotron emission by these secondary electrons is not consistent with observations of the Coma cluster. Thus the hypothesis can be ruled out on cluster scales.
42969120
Quark compositeness, new physics, and ultrahigh-energy cosmic-ray double-core gamma -family events.
We find a significant excess of ultrahigh-energy cosmic-ray events at large transverse momenta with respect to the prediction by standard perturbative QCD at E(lab) approximately 10(4)-10(5) TeV, an energy regime beyond the reach of existing colliders but within the range of future hadron colliders. Such a large deviation cannot be accounted for by a compositeness model of quarks with a characteristic energy scale LAMBDA(c) > 1.4 TeV allowed by current collider experiments, pointing towards new physics.
39230762
Exact identities in the Hubbard model and t-J model.
Exact identities among the nth extended s-wave-pairing amplitudes in the Hubbard model are presented. They provide more constraints on the possible symmetries of the superconducting gap in the Hubbard model than that between the on-site and the first extended s-wave pairings pointed out by Zhang. For the t-J model, we also find an exact identity between the on-site and the first extended s-wave-pairing amplitudes, which is essentially consistent with that in the Hubbard model. Besides the s-wave pairings, we discuss the constraints on the other pairing amplitudes