Bell inequalities resistant to detector inefficiency

We derive both numerically and analytically Bell inequalities and quantum measurements that present enhanced resistance to detector inefficiency. In particular, we describe several Bell inequalities which appear to be optimal with respect to inefficient detectors for small dimensionality d=2, 3, 4 and two or more measurement settings at each side. We also generalize the family of Bell inequalities described by Collins et al. Phys. Rev. Lett. 88, 040404 (2002) to take into account the inefficiency of detectors. In addition, we consider the possibility for pairs of entangled particles to be produced with probability less than 1. We show that when the pair production probability is small, one should in general use different Bell inequalities than when the pair production probability is high.