arXiv subjects

G. Bell

Publications and source records attributed to G. Bell.

40 records · Page 3Linked to original sources

arXiv2005

Heavy-to-light form factors for non-relativistic bound states

We investigate transition form factors between non-relativistic QCD bound states at large recoil energy. Assuming the decaying quark to be much heavier than its decay product, the relativistic dynamics can be treated according to the factorization formula for heavy-to-light form factors obtained from the heavy-quark expansion in QCD. The non-relativistic expansion determines the bound-state wave functions to be Coulomb-like. As a consequence, one can explicitly calculate the so-called ``soft-overlap'' contribution to the transition form factor.

hep-ph↗

arXiv2005

Asymptotic dimension in Bedlewo

This survey was compiled from lectures and problem sessions at the International Conference on Geometric Topology at the Mathematical Research and Conference Center in Bedlewo, Poland in July 2005.

math.GR↗

arXiv2002

On asymptotic dimension of groups acting on trees

We prove the following theorem: Let $π$ be the fundamental group of a finite graph of groups with finitely generated vertex groups $G_v$ having asdim $G_v\le n$ for all vertices $v$. Then asdim$π\le n+1$. This gives the best possible estimate for the asymptotic dimension of an HNN extension and the amalgamated product.

math.GR↗

arXiv2001

On asymptotic dimension of groups

We prove a version of the countable union theorem for asymptotic dimension and we apply it to groups acting on asymptotically finite dimensional metric spaces. As a consequence we obtain the following finite dimensionality theorems. A) An amalgamated product of asymptotically finite dimensional groups has finite asymptotic dimension: asdim A *_C B < infinity. B) Suppose that G' is an HNN extension of a group G with asdim G < infinity. Then asdim G'< infinity. C) Suppose that Γis Davis' group constructed from a group πwith asdimπ< infinity. Then asdimΓ< infinity.

math.GR↗