Wed·Aug 22, 2007Wednesday·August 22, 2007

1. 01*

   Energies of B_s meson excited states - a lattice study

   UKQCD Collaboration: J. Koponen🇫🇮

   This is a follow-up to our earlier work on the energies and radial distributions of heavy-light mesons. The heavy quark is taken to be static (infinitely heavy) and the light quark has a mass about that of the strange quark. We now concentrate on the energies of the excited states with higher angular momentum and with a radial node. A new improvement is the use of hypercubic blocking in the time direction. The calculation is carried out with dynamical fermions on a 16 cubed times 32 lattice with a lattice spacing approximately 0.1 fm generated using a non-perturbatively improved clover action. In nature the closest equivalent of this heavy-light system is the B_s meson, which allows us to compare our lattice calculations to experimental results (where available) or to give a prediction where the excited states, particularly P-wave states, should lie. We pay special attention to the spin-orbit splitting, to see which one of the states (for a given angular momentum L) has the lower energy. An attempt is made to understand these results in terms of the Dirac equation.

   hep-lathep-phPRD(2008)·25 citations
2. 02*

   Lattice study of monopoles in the Electroweak theory

   B. L. G. Bakker🇳🇱 · A. I. Veselov🇷🇺 · M. A. Zubkov🇷🇺

   We investigated numerically properties of Nambu monopoles in lattice Electroweak theory at realistic values of $\alpha$ and ${\theta }_W$. Our choice of parameters of lattice Lagrangian corresponds to large values of the Higgs boson mass $M_H>2M_W$. We find that the density of Nambu monopoles cannot be predicted by the choice of the initial parameters of Electroweak theory and should be considered as the new external parameter of the theory. We also investigate the difference between the versions of Electroweak theory with the gauge groups $SU(2)\otimes U(1)$ and $SU(2)\otimes U(1)/Z_2$. We do not detect any difference at $\alpha \sim 1/128$. However, such a difference appears in the strong coupling region and is related to the properties of monopoles constructed of the hypercharge field.

   hep-lathep-phPoS(2007)·5 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.