Tagging $b$ quarks at extreme energies without tracks
  We describe a new hit-based $b$-tagging technique for high energy jets and study its performance with a Geant4-based simulation. The technique uses the fact that at sufficiently high energy a B meson or baryon can live long enough to traverse the inner layers of pixel detectors such as those in the ATLAS, ALICE, or CMS experiments prior to decay. By first defining a "jet" via the calorimeter, and then counting hits within that jet between pixel layers at increasing radii, we show it is possible to identify jets that contain $b$-quarks by detecting a jump in the number of hits. We show that the technique maintains its efficiency at energies beyond the range of conventional $b$-taggers. 
B. Todd Huffman (1), Charles Jackson (1) and Jeff Tseng (1) ((1)   Oxford University)
hep-ex hep-ph