$B^\pm$ mass reconstruction in $B^\pm\to J/\psi K^\pm$ decay at ATLAS at 13 TeV $pp$ collisions at the LHC

The performance of the ATLAS detector in reconstructing $B^\pm$ candidates is tested using 3.2 fb$^{−1}$ of $pp$ collision data from the LHC at a centre of mass energy of 13 TeV. The $B^\pm$ invariant mass is determined via the $B^\pm\to J/\psi(\mu^+\mu^-)K^\pm$ decay. The $B^\pm$ mass is extracted in several rapidity intervals and used to test the momentum calibration of Inner Detector tracking at low-to-medium transverse momentum ($p_T$) values. This study of the Inner Detector performance is a necessary prerequisite to future $B$-physics analyses with the ATLAS detector as the tracking performance determines the precision of these measurements.