arXiv subjects

Zhenqi Shen

Publications and source records attributed to Zhenqi Shen.

9 recordsLinked to original sources

arXiv2016

The chaotic effects in a nonlinear QCD evolution equation

The corrections of gluon fusion to the DGLAP and BFKL equations are discussed in a united partonic framework. The resulting nonlinear evolution equations are the well-known GLR-MQ-ZRS equation and a new evolution equation. Using the available saturation models as input, we find that the new evolution equation has the chaos solution with positive Lyaponov exponents in the perturbative range. We predict a new kind of shadowing caused by chaos, which blocks the QCD evolution in a critical small $x$ range. The blocking effect in the evolution equation may explain the Abelian gluon assumption and even influence our expectations to the projected Large Hadron Electron Collider (LHeC), Very Large Hadron Collider (VLHC) and the upgrade (CppC) in a circular $e^+e^-$ collider (SppC).

hep-ph↗

arXiv2016

A new perspective on gluon distribution at small x

The corrections of the gluon fusion to the BFKL equation in a unified partonic framework are studied. This modified BFKL equation predicts a stronger shadowing, which suppresses the gluon density and even leads to the gluon disappearance below the saturation region. We suggest that this unexpected effect is caused by a possible chaotic solution of the new equation.

hep-ph↗

arXiv2014

Parton recombination effect in polarized parton distributions

Parton recombination corrections to the standard spin-dependent Altarelli-Parisi evolution equation are considered in a nonlinear evolution equation. The properties of this recombination equation and its relation with the spin-averaged form are discussed.

hep-ph↗

arXiv2013

Properties of the gluon recombination functions

The gluon recombination functions in the twist-4 QCD evolution equations are studied at the leading logarithmic approximation using both the covariant and non-covariant methods. We justify that the infrared singularities in the twist-4 coefficient functions impede us to simply separate the QCD evolution kernels from the coefficient functions at the equivalent particle approximation. In particulary, we point out that the gluon recombination functions in the GLR-MQ evolution equation are unavailable. The methods avoiding the IR divergences are discussed, which can be used in the derivations of the evolution kernels and coefficient functions at the higher twist level.

hep-ph↗

arXiv2008

Can a chaotic solution in the QCD evolution equation restrain high-energy collider physics?

We indicate that the random aperiodic oscillation of the gluon distributions in a modified Balisky--Fadin--Kuraev--Lipatov (BFKL) equation has positive Lyapunov exponents. This first example of chaos in QCD evolution equations, raises the sudden disappearance of the gluon distributions at a critical small value of the Bjorken variable $x$ and may stop the increase of the new particle events in an ultra high energy hadron collider.

hep-ph↗

arXiv2008

Can a chaos term in the QCD evolution equation restrain high-energy collider physics?

We indicate that the random aperiodic oscillation of the gluon distributions in a modified BFKL equation has the positive Lyapunov exponents. This first example of chaos in QCD evolution equations, raises the sudden disappearance of the gluon distributions at a critical small value of the Bjorken variable $x$ and may stop the increase of the new particle events in a ultra high energy hadron collider.

hep-ph↗

arXiv2008

Nuclear Shadowing and Antishadowing in a Unitarized BFKL Equation

The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation. The $Q^2$- and $x$-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.

hep-ph↗

arXiv2006

Antishadowing effects in the unitarized BFKL equation

A unitarized BFKL equation incorporating shadowing and antishadowing corrections of the gluon recombination is proposed. This equation reduces to the Balitsky-Kovchegov evolution equation near the saturation limit. We find that the antishadowing effects have a sizeable influence on the gluon distribution function in the preasymptotic regime.

hep-ph↗

arXiv2006

A unity of QCD evolution dynamics at small $x$ region

The DGLAP, BFKL, modified DGLAP and modified BFKL equations are constructed in a unified partonic framework. The antishadowing effect in the recombination process is emphasized, which leads to two different small $x$ behaviors of gluon distribution. In the meantime, the BFKL equation and modified DGLAP equation are viewed as the corrections of the initial gluon correlations to the evolution dynamics at twist-2 and twist-4, respectively. A partonic explanation of Regge theory for the BFKL dynamics and the relation of the BFKL dynamics with the helicity configuration of the initial gluons are presented.

hep-ph↗