Kaon bag parameter B_K at the physical mass point

A summary of the recent determination of the kaon bag parameter B_K by the Budapest-Marseille-Wuppertal collaboration is given. We use a subset of our new 2+1 flavor ensembles with tree-level Symanzik glue and 2-step HEX-smeared clover fermions, featuring pion masses between 120 MeV and 380 MeV, a total of 4 lattice spacings (at 2 of which the physical mass point is reached) and large volumes (up to 6 fm). We use the RI/MOM scheme with trace subtraction to renormalize the data non-perturbatively. We find B^RI _K (3.5 GeV) = 0.5308(56)(23) at the physical mass point, in the continuum and in infinite volume, with all systematics accounted for. Finally, the details of the conversion to RGI and MS conventions are discussed.