Probing the Heavy Quark Content of the Photon Using b Tagging at High   Energy $e\gamma$ and $e^+e^-$ Colliders
  We suggest a method for probing the quark content of the photon using $b$ tagging at high energy $e^+e^-$ and $e\gamma$ colliders. We find that heavy quark tagging provides a sensitive and effective probe of the quark content of the photon especially in the low $x$-region where the various models differ the most. This process is complementary to others that have been studied in the literature and can contribute to more precise determinations of quark and gluon distributions inside the photon. 
Michael A. Doncheski, Stephen Godfrey and K. Andrew Peterson