Branching ratio measurement for rare annihilation decay
| dc.contributor.advisor | Rajeev Kumar | |
| dc.contributor.author | Dua, Titiksha | |
| dc.date.accessioned | 2019-04-22T14:01:27Z | |
| dc.date.available | 2019-04-22T14:01:27Z | |
| dc.date.issued | 2019 | |
| dc.description.abstract | The research is based on study of the rare radiative decay B^0→J/ψγ, using data collected (corresponding to 772×〖10〗^6 BB ̅ pairs) by the Belle detector at Υ(4S) resonance at asymmetric e^+ e^- collider at KEK, Japan during its long run. In this annihilation decay, there is potential sign of New Physics from the possibility of (V+A) charged current admixture to the standard (V−A) current. Branching ratio measurement will help test the validity of various QCD models. A large Monte Carlo sample is generated to determine the signal reconstruction efficiency, which is obtained as 33.9±0.19%. The energy difference, ΔE=E_B^*-E_beam^*, the beam-constrained mass M_bc=√(E_beam^(*2)-p_B^(*2) ) and helicity (cosθ) of J/ψ are used for signal extraction, where E_beam^* is the run dependent beam energy, E_B^* and p_B^* are the reconstructed energy and momentum, respectively of the B meson candidates in the center-of-mass frame. The peaking background in the signal region is dominated by B^0→J/ψ π^0 (π^0→ γγ), B^0→J/ψη (η→ γγ) mainly and also B^0→J/ψ K_L (K_L→3π^0 or 6γ) and B^0→J/ψ K_S and other combinatorial backgrounds. To suppress these backgrounds, we vetoed these photons that when combine with another photon of energy E_γ> 60 MeV and form a π^0 (η) candidate. Whereas, B→J/ψK_S and B→J/ψK_L are not peaking in ΔE but are peaking in M_bc signal region. The peaking backgrounds B→J/ψη and B→J/ψπ^0 correspond to 103.56±3.29 events. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810100817 | |
| dc.keywords | Belle detector, KEK, B mesons, V+A current, helicity | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 77 | en_US |
| dc.publisher | Punjab Agricultural University, Ludhiana | en_US |
| dc.research.problem | Branching ratio measurement for rare annihilation decay | en_US |
| dc.sub | Mathematics | en_US |
| dc.subject | null | en_US |
| dc.theme | Branching ratio measurement for rare annihilation decay | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | Branching ratio measurement for rare annihilation decay | en_US |
| dc.type | Thesis | en_US |