Prediction of the bottomonium D-wave spectrum from full lattice QCD

We calculate the full spectrum of D-wave states in the Upsilon system in lattice QCD for the first time, using an improved version of NonRelativistic QCD on coarse and fine "second generation" gluon field configurations from the MILC collaboration that include the effect of up, down, strange and charm quarks in the sea. Taking the 2S-1S splitting to set the lattice spacing, we determine the ^3D_2 - 1S splitting to 2.3%, and find agreement with experiment. Our prediction of the fine structure relative to the ^3D_2 gives the ^3D_3 at 10.181(5) GeV and the ^3D_1 at 10.147(6) GeV. We also discuss the overlap of ^3D_1 operators with ^3S_1 states.Comment: 4 pages, 5 figure

Collective hydrogen-bond rearrangement dynamics in liquid water

We investigate barrier-crossing processes corresponding to collective hydrogen-bond rearrangements in liquid water using Markov state modeling techniques. The analysis is based on trajectories from classical molecular dynamics simulations and accounts for the full dynamics of relative angular and separation coordinates of water clusters and requires no predefined hydrogen bond criterium. We account for the complete 12-dimensional conformational subspace of three water molecules and distinguish five well-separated slow dynamic processes with relaxation times in the picosecond range, followed by a quasi-continuum spectrum of faster modes. By analysis of the Markov eigenstates, these processes are shown to correspond to different collective interchanges of hydrogen-bond donors and acceptors. Using a projection onto hydrogen-bond states, we also analyze the switching of one hydrogen bond between two acceptor water molecules and derive the complete transition network. The most probable pathway corresponds to a direct switch without an intermediate, in agreement with previous studies. However, a considerable fraction of paths proceeds along alternative routes that involve different intermediate states with short-lived alternative hydrogen bonds or weakly bound states