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Flavor Asymmetry of the Nucleon Sea and the Five-Quark Components of the Nucleons

Wen-Chen Chang, Jen-Chieh Peng

TL;DR

The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons.

Abstract

The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the $\bar d - \bar u$ and $\bar u + \bar d - s -\bar s$ data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the $|uudu\bar{u}>$ and $|uudd\bar{d}>$ Fock states are also extracted.

Flavor Asymmetry of the Nucleon Sea and the Five-Quark Components of the Nucleons

TL;DR

The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons.

Abstract

The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the and data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the and Fock states are also extracted.

Paper Structure

This paper contains 7 equations, 3 figures.

Figures (3)

  • Figure 1: The $x$ distributions of the intrinsic $\bar{Q}$ in the $u u d Q \bar{Q}$ configuration of the proton from the BHPS model brodsky80. The solid curve is plotted using the expression in Eq. \ref{['eq:prob5q_d']} for $\bar{c}$. The other three curves, corresponding to $\bar{c}$, $\bar{s}$, and $\bar{d}$ in the five-quark configurations, are obtained by solving Eq. \ref{['eq:prob5q_a']} numerically. The same probability ${\cal P}^{Q \bar{Q}}_5$ (${\cal P}^{Q \bar{Q}}_5= 0.01$) is used for the three different five-quark states.
  • Figure 2: Comparison of the $\bar{d}(x) - \bar{u}(x)$ data with the calculations based on the BHPS model. The dashed curve corresponds to the calculation using Eq. \ref{['eq:prob5q_a']} and Eq. \ref{['eq:intdbarubar2']}, and the solid and dotted curves are obtained by evolving the BHPS result to $Q^2 = 54.0$ GeV$^2$ using $\mu = 0.5$ GeV and $\mu = 0.3$ GeV, respectively.
  • Figure 3: Comparison of the $x(\bar{d}(x) + \bar{u}(x) - s(x) - \bar{s}(x))$ data with the calculations based on the BHPS model. The dashed curve corresponds to the calculation using Eq. \ref{['eq:prob5q_a']}, and the solid and dotted curves are obtained by evolving the BHPS result to $Q^2 = 2.5$ GeV$^2$ using $\mu = 0.5$ GeV and $\mu = 0.3$ GeV, respectively.