Tagging b-jets using low-p_T electrons

This note presents a study of b-jet tagging in ATLAS using soft electrons from semileptonic b-quark decays. Both Inner Detector and EM Calorimeter information is used by the b-tagging algorithm to identify signal electrons inside jets. The performance of this algorithm in terms of expected b-tagging efficiency and non-b jet rejection is discussed in detail over the small central rapidity range and for low luminosity operation. For an algorithm efficiency of 50%$ (and an overall efficiency of 7.2% taking into account the branching ratio of b to e decays), rejections of 554 against u-jets, 192 against gluon jets and of 47 against c-jets can be achieved. Such a soft-electron b-tagging algorithm can be combined with the higher-efficiency vertexing algorithm to improve the b-jet tagging performance.