The Similarity Renormalization Group for three bosons in a momentum-space partial-wave basis
Ladda ner
Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Fundamental physics, MSc
Publicerad
2012
Författare
Carlsson, Boris
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The Similarity Renormalization Group (SRG) flow equation is explored for systems of two and three spinless bosons in a momentum-space partial-wave basis. The two- and three-body binding energies as well as the phaseshifts are used to gauge that the transformation is unitary and to study how well the SRG decouples high- and low-energy physics. I consider four different potentials with different characteristics: Two simplied nucleon potentials and two inter-atomic helium potentials (a soft-core potential and the state-of-the-art LM2M2 potential that is fitted to a wealth of experimental data). An initial three-body force is included for two of these potentials. Even with only two-body terms in the initial hamiltonian, SRG induced many-body forces are shown to arise during the transformation. These induced forces are computed for the three-body system and their evolution is studied as a function of the flow parameter. In all cases the SRG transformed potentials display greatly improved decoupling. This is achieved with a three-body binding-energy deviation of less than 0.1% in all cases except for the soft-core helium potential.
Beskrivning
Ämne/nyckelord
Grundläggande vetenskaper , Lågenergifysik , Atomfysik , Beräkningsfysik , Basic Sciences , Low energy physics , Atomic physics , Computational physics