Search for New Physics Using Radiative B Meson Decays and Lifetime Measurment of the B Meson with the Belle II Experiment
Search for New Physics Using Radiative B Meson Decays and Lifetime Measurment of the B Meson with the Belle II Experiment

Author: Reem Rasheed

Publisher:

Published: 2020

Total Pages: 0

ISBN-13:

DOWNLOAD EBOOK

After the Big Bang matter and antimatter were present in equal amounts. Today, however, everything we see, is made almost entirely of matter. A fundamental ingredient to explain this asymmetry between matter and antimatter is the violation of the CP (Charge Parity) symmetry. CP violation has been observed but quantitatively not enough to explain the huge asymmetry. The Belle II experiment in Japan studies the particles produced in electron-positron collisions at the SuperKEKB collider, the highest intensity collider in the World, allowing a high precision measurements of the known sources of CP violation and looking for new ones. In my PhD, I worked on measuring the CP violation in B meson radiative decays (decays with photon in final state) particularly promising thanks to their high sensitivity to possible new processes. Following this analysis, I started a new measurement of the B mesons lifetime where I could verify the robustness of the tools used in the CP violation measurement.

A Search for the Rare Decay [B Meson to Two Photons]
A Search for the Rare Decay [B Meson to Two Photons]

Author: Andrew Michael Ruland

Publisher:

Published: 2010

Total Pages: 362

ISBN-13:

DOWNLOAD EBOOK

This thesis describes a search for the rare radiative decay of a B meson to two photons. where the charged congugate mode is implied throughout. These decays are highly suppressed in the Standard Model where the branching fraction is expected to be of order 10^-8. In some new physics scenarios this could be enhanced by up to an order of magnitude to 10^-7. Therefore an observation of a significant signal above the Standard Model prediction could be a sign of new physics. The search for this rare decay was performed using the data collected with the BaBar detector at the SLAC National Accelerator Laboratory PEP-II storage ring operating at the Upsilon(4S) resonance. The analysis uses a dataset with an integrated luminosity of 425.7 fb-1 corresponding to 467 million BB pairs. A signal yield of 21.3 +12.8 -11.8 events with a significance of 1.88 sigma was measured using an unbinned extended maximum likelihood fit. An upper limit on the branching fraction is set at the 90% confidence level of less than 3.2 times 10^-7. This is about two times more stringent than the best upper limit of less than 6.2 times 10^-7 published by the Belle collaboration.

Radiative and Leptonic B-meson Decays from the B-factories
Radiative and Leptonic B-meson Decays from the B-factories

Author:

Publisher:

Published: 2011

Total Pages: 7

ISBN-13:

DOWNLOAD EBOOK

Radiative and leptonic decays of B-mesons represent an excellent laboratory for the search for New Physics. I present here recent results on radiative and leptonic decays from the Belle and BABAR collaborations. Radiative penguin and leptonic B-meson decays are excellent probes for investigating the effects of New Physics. Although current measurements are in agreement with the Standard Model expectations, they are still quite useful for setting bounds on possible NP models. The B → X{sub s}[gamma] and B → [tau][nu] measurements, for example, put strong constraints on the mass of charged Higgs bosons in Type II two-Higgs double models. The B → X{sub s}[gamma] branching fraction measurements also constrain models with universal extra dimensions.

Radiative B Meson Decay as a Probe of Physics Beyond the Standard Model
Radiative B Meson Decay as a Probe of Physics Beyond the Standard Model

Author:

Publisher:

Published: 2009

Total Pages: 158

ISBN-13:

DOWNLOAD EBOOK

The author presents measurements of radiative B meson decays to the final states Ks0?0? and K?? based on data collected at the ?(4S) resonance with the BABAR detector at the PEP-II e+e- collider at SLAC. In a data sample of 467 million B$ar{B}$ pairs, the time-dependent CP asymmetry in B0 → Ks0?0? decays is measured in two regions of Ks0-?0 invariant mass. In the K* region, 0.8 m(Ksubs/subsup0/sup?sup0/sup) 1.0 GeV/csup2/sup, we find SsubK*?/sub = -0.03 ± 0.29 ± 0.03 and CsubK*?/sub = -0.14 ± 0.16 ± 0.03; in the range 1.1 m(Ksubs/subsup0/sup?sup0/sup) 1.8 GeV/csup2/sup, they find SsubKsubs/subsup0/sup/sub?sup0/sup? = -0.78 ± 0.59 ± 0.09 and C subKsubs/subsup0/sup/sub?sup0/sup? = -0.36 ± 0.33 ± 0.04. With a sample of 228 million B$ar{B}$ pairs they measure the branching fraction ?(Bsup+/sup → Ksup+/sup??) = (3.5 ± 0.6 ± 0.4) x 10sup-6/sup and set the limit ?(Bsup0/sup→ Ksup0/sup??) 2.7 x 10sup-6/sup at 90% confidence level. The direct CP asymmetry in Bsup+

Radiative Leptonic B Decays
Radiative Leptonic B Decays

Author:

Publisher:

Published: 2007

Total Pages: 312

ISBN-13:

DOWNLOAD EBOOK

We present the results of a search for B+ meson decays into [gamma]l+vl, where l = e, [mu]. We use a sample of 232 million B$\bar{B}$ meson pairs recorded at the [Upsilon](4S) resonance with the BABAR detector at the PEP-II B factory. We measure a partial branching fraction [Delta][beta] in a restricted region of phase space that reduces the effect of theoretical uncertainties, requiring the lepton energy to be in the range 1.875 and 2.850 GeV, the photon energy to be in the range 0.45 and 2.35 GeV, and the cosine of the angle between the lepton and photon momenta to be less than -0.36, with all quantities computed in the [Upsilon](4S) center-of-mass frame. We find [Delta][beta](B+ 2![gamma]l+vl) = ( -0.31.5+1.3(statistical) -0.6+0.6(systematic) ± 0.1(theoretical)) x 10-6, under the assumption of lepton universality. Interpreted as a 90% confidence-level Bayesian upper limit, the result corresponds to 1.7 x 10-6 for a prior at in amplitude, and 2.3 x 10-6 for a prior at in branching fraction.