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Title: Measurement of CKM-angle γ with Charmed B 0 Meson Decays

Abstract

This thesis reports measurements of the time-dependent CP asymmetries in fully reconstructed B 0 → (D (*)∓π ± and B 0 → D ρ ± ) decays in approximately 232 million Y(4S) → B$$\bar{B}$$ events, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center in California, as published in Ref. [14]. The phenomenon of CP violation allows one to distinguish between matter and antimatter, and, as such, is one of the essential ingredients needed to explain the apparent abundance of matter over antimatter in the universe. The Standard Model describes the observed elementary particles in terms of three generations of quarks and leptons, as well as the weak, electromagnetic, and strong interactions between them. In the Standard Model, CP violation is incorporated in the Cabibbo-Kobayashi-Maskawa (CKM) matrix, which describes the weak interactions between the quarks. The weak interactions between quarks are described by coupling constants that are functions of three real parameters and one irreducible complex phase. The magnitude of all CP violating effects in the Standard Model is related to this complex phase. The measurement of the CP violating phase of the CKM matrix is an important part of the present scientific program in particle physics. Violation of the CP symmetry manifests itself as a non-zero area of the Unitarity Triangle. The Unitarity Triangle needs to be overconstrained by experimental measurements in order to demonstrate that the CKM mechanism is the correct explanation of this phenomenon. No stringent measurement of the CKM-angle γ is yet available.

Authors:
 [1]
  1. Univ. of Amsterdam (Netherlands)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
922607
Report Number(s):
SLAC-R-858
TRN: US0801166
DOE Contract Number:
AC02-76SF00515
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ABUNDANCE; ANTIMATTER; COUPLING CONSTANTS; ELEMENTARY PARTICLES; LEPTONS; MESONS; PHYSICS; QUARKS; STANDARD MODEL; STRONG INTERACTIONS; SYMMETRY; UNITARITY; UNIVERSE; WEAK INTERACTIONS; Experiment-HEP; HEPEX; HEPPH; HEPTH

Citation Formats

Baak, Max Arjen. Measurement of CKM-angle γ with Charmed B0 Meson Decays. United States: N. p., 2007. Web. doi:10.2172/922607.
Baak, Max Arjen. Measurement of CKM-angle γ with Charmed B0 Meson Decays. United States. doi:10.2172/922607.
Baak, Max Arjen. Mon . "Measurement of CKM-angle γ with Charmed B0 Meson Decays". United States. doi:10.2172/922607. https://www.osti.gov/servlets/purl/922607.
@article{osti_922607,
title = {Measurement of CKM-angle γ with Charmed B0 Meson Decays},
author = {Baak, Max Arjen},
abstractNote = {This thesis reports measurements of the time-dependent CP asymmetries in fully reconstructed B0 → (D (*)∓π± and B0 → D∓ ρ± ) decays in approximately 232 million Y(4S) → B$\bar{B}$ events, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center in California, as published in Ref. [14]. The phenomenon of CP violation allows one to distinguish between matter and antimatter, and, as such, is one of the essential ingredients needed to explain the apparent abundance of matter over antimatter in the universe. The Standard Model describes the observed elementary particles in terms of three generations of quarks and leptons, as well as the weak, electromagnetic, and strong interactions between them. In the Standard Model, CP violation is incorporated in the Cabibbo-Kobayashi-Maskawa (CKM) matrix, which describes the weak interactions between the quarks. The weak interactions between quarks are described by coupling constants that are functions of three real parameters and one irreducible complex phase. The magnitude of all CP violating effects in the Standard Model is related to this complex phase. The measurement of the CP violating phase of the CKM matrix is an important part of the present scientific program in particle physics. Violation of the CP symmetry manifests itself as a non-zero area of the Unitarity Triangle. The Unitarity Triangle needs to be overconstrained by experimental measurements in order to demonstrate that the CKM mechanism is the correct explanation of this phenomenon. No stringent measurement of the CKM-angle γ is yet available.},
doi = {10.2172/922607},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Feb 05 00:00:00 EST 2007},
month = {Mon Feb 05 00:00:00 EST 2007}
}

Thesis/Dissertation:
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  • Despite more than thirty years having elapsed since the discovery of CP violation, our understanding about the source and the nature of this phenomenon is still very limited. In the standard model of particle physics, CP violation is due to the presence of an non-irreducible weak phase in the Cabibbo-Kabayashi-Maskawa(CKM) matrix. Up to now, all the experimental results are in good agreement with the standard model. However, it is important for us to over-constrain the CKM quark-mixing matrix and explore the possibility of new physics beyond the standard model. The B meson provides an ideal place to measure CP violation due to its heavy mass and potentially large CP-violating effects. In particular, the angle γ of the Unitary Triangle relating the elements of the CKM matrix is extremely crucial in terms of CP violation and constraints on the new physics models. Various methods using B - → D 0K - decays have been proposed to measure based on the interference between the V cb and V ub amplitudes. Despite the simple concept, the measurement turns out to be experimentally challenging due to the small branching fraction and the small value of τ B, the amplitude ratio between the two contributing Feynman diagrams. In this thesis a novel technique to measure γ in B - → D (*) K - decay using a Dalitz plot analysis of D 0 → K{sub s}π +π - is presented. Until the turn on of LHC b [1] later in the decade, this remains the most promising method to measure γ. This thesis is roughly separated into two parts. The first part involves a study of hadron spectroscopy and the Dalitz plot analysis of the D 0→ Kmore » $$0\atop{S}$$π +π -. The second part of the thesis involves the measurement of γ in B - → D (*) K - using the results of the D 0 → K$$0\atop{S}$$π +π - dalitz plot analysis.« less
  • In the Standard Model, CP violation in weak interactions involving quarks is parameterized by an irreducible complex phase in the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing-matrix. The precise determination of the CKM elements is a necessary ingredient for a stringent test of the Standard Model predictions, and is a crucial input for reducing the theoretical error in many New Physics searches with flavor, e.g., in the kaon sector. The unitarity of the CKM matrix is typically expressed as a triangle relationship among its parameters, where the area of the so-called Unitarity Triangle visually depicts the amount of asymmetry between the decays of B particles and their antimatter counterparts. In the past few years, the BABAR and Belle experiments have been able to measure all three angles of the triangle from CP asymmetry measurements. The first asymmetry measurements in B particle decays, about ten years ago, allowed to determine β, which is now known to better than 5% precision. The angles α and γ, measured in much rarer processes, required several years of data taking before analyses could yield reliable answers. A remarkable feature is that the direct measurement of the angles of the Unitarity Triangle generates an area that is consistent with the area predicted by measurement of the sides. In this thesis we have presented the branching fraction measurements of charged and neutral B meson decays to K 1(1270)π and K 1(1400)π, obtained from a data sample of 454 million Υ(4S) → Bmore » $$\bar{B}$$ events. This analysis is particularly challenging from the experimental side since the branching fractions involved are very low, at the level of 10 -6 - 10 -7, and the signal is characterized by the simultaneous presence of two overlapping resonances, which exhibit sizeable interference effects. The combined K 1(1270)π and K 1(1400)π signal is therefore modeled with a K-matrix formalism, which accounts for the effects of interference between the K 1(1270) and K 1(1400) mesons by introducing two effective parameters. The model is derived from the analysis, performed by the ACCMOR Collaboration, of the diffractive production of strange mesons.« less
  • The author presents measurements of radiative B meson decays to the final states K s 0π 0γ and KΦγ based on data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e +e - collider at SLAC. In a data sample of 467 million Bmore » $$\bar{B}$$ pairs, the time-dependent CP asymmetry in B 0 → K s 0π 0γ decays is measured in two regions of K s 00 invariant mass. In the K* region, 0.8 < m(K s 0π 0) < 1.0 GeV/c 2, we find S K*γ = -0.03 ± 0.29 ± 0.03 and C K*γ = -0.14 ± 0.16 ± 0.03; in the range 1.1 < m(K s 0π 0) < 1.8 GeV/c 2, they find S Ks0π 0γ = -0.78 ± 0.59 ± 0.09 and C Ks0π 0γ = -0.36 ± 0.33 ± 0.04. With a sample of 228 million B$$\bar{B}$$ pairs they measure the branching fraction β(B + → K +Φγ) = (3.5 ± 0.6 ± 0.4) x 10 -6 and set the limit β(B 0→ K 0Φγ) < 2.7 x 10 -6 at 90% confidence level. The direct CP asymmetry in B + → K +Φγ is found to be A CP = (-26 ±14 ± 5)%. In each case the uncertainties are statistical and systematic, respectively.« less
  • This study reports measurements of the branching fractions of B meson decays to {eta}{prime}K{sup +}, {eta}{prime}K{sup 0}, {omega}{pi}{sup +}, {omega}K{sup +}, and {omega}K{sup 0}. Charge asymmetries are measured for the charged modes and the time-dependent CP-violation parameters S and C are measured for the neutral modes. The results are based on a data sample of 347 fb{sup -1} containing 383 million B{bar B} pairs recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring located at the Stanford Linear Accelerator Center. Statistically significant signals are observed for all channels with the following results: B(B{sup +} {yields} {eta}{prime}K{sup +})more » = (70.0{+-}1.5{+-}2.8)x10{sup -6}, B(B{sup 0} {yields} {eta}{prime}K{sup 0}) = (66.6{+-}2.6{+-}2.8)x10{sup -6}, B(B{sup +} {yields} {omega}{pi}{sup +}) = (6.7{+-}0.5{+-}0.4)x10{sup -6}, B(B{sup +} {yields} {omega}K{sup +}) = (6.3{+-}0.5{+-}0.3)x10-6, and B(B{sup 0} {yields} ?K0) = (5.6{+-}0.8{+-}0.3)x10-6, where the first uncertainty is statistical and the second is systematic. We measure A{sub ch}({eta}{prime}K{sup +}) = +0.010{+-}0.022{+-}0.006, A{sub ch}({omega}{pi}{sup +}) = -0.02{+-}0.08{+-}0.01, A{sub ch}({omega}K{sup +}) = -0.01{+-}0.07{+-}0.01, S{sub {eta}{prime}K{sup 0}{sub S}} = 0.56{+-}0.12{+-}0.02, C{sub {eta}{prime}K{sup 0}{sub S}} = -0.24 {+-} 0.08 {+-} 0.03, S{sub {omega}{prime}K{sup 0}{sub S}} = 0.62+0.25 -0.29 {+-} 0.02, and C{sub {omega}{prime}K{sup 0}{sub S}} = -0.39+0.25 -0.24 {+-} 0.03. The result in S{sub {eta}{prime}K{sup 0}{sub S}} contributes to the published measurement from BABAR, which differs from zero by 5.5 standard deviations and is the first observation of mixing-induced CP-violation in a charmless B decay.« less
  • Over the last few years, the B factories have established the Cabbibo-Kobayashi-Maskawa mechanism of CP violation in the Standard Model through the study of the decays of B mesons. The focus of Belle and BaBar has now expanded to the search for signatures of new physics beyond the Standard Model, particularly through examination of flavor-changing neutral-current transitions, which proceed through diagrams involving virtual loops. These decays are suppressed in the Standard Model, increasing sensitivity to new-physics effects but decreasing branching fractions. Exploiting large and growing datasets, BaBar and Belle have made many measurements in loop decays where a b quarkmore » transitions to an s quark, observing hints of possible deviations from Standard Model expectations in CP-violating measurements.« less