The Measurement of CP Asymmetries in the Three-Body Charmless Decay Neutral B Meson Decays to Neutral Kaon(S) Neutral Kaon(S) Neutral Kaon(S). PDF Download
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Author: Haleh K. Hadavand
Publisher:
ISBN:
Category :
Languages : en
Pages : 170
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In this dissertation, a measurement of CP-violating effects in decays of neutral B mesons is presented. The data sample for this measurement consists of about 272 million {Upsilon}(4S) {yields} B{bar B} decays collected between 1999 and 2004 with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider, located at the Stanford Linear Accelerator Center. One neutral B meson is fully reconstructed in the CP eigenstate B{sup 0} {yields} K{sub S}{sup 0} K{sub S}{sup 0} K{sub S}{sup 0}. The other B meson is determined to be either a B{sup 0} or a {bar B}{sup 0}, at the time of its decay, from the properties of its decay products. The proper time {Delta}t elapsed between the decay of the two mesons is determined by reconstructing their decay vertices, and by measuring the distance between them. A novel technique for determining the B vertex of the decay to the CP eigenstate B{sup 0} {yields} K{sub S}{sup 0} K{sub S}{sup 0} K{sub S}{sup 0} has been applied since the tracks in the final state do not originate from the B decay vertex. The time-dependent CP asymmetry amplitudes are determined by the distributions of {Delta}t in events with a reconstructed B meson in the CP eigenstate. The detector resolution and the b flavor tagging parameters are constrained by the {Delta}t distributions of events with a fully reconstructed flavor eigenstate. Because of the special topology of this decay, the detector resolution on {Delta}t must be checked for consistency with decays with tracks which originate from the B decay. From a maximum likelihood fit to the {Delta}t distributions of all selected events, the value of the CP violating asymmetries are measured to be S{sub 3K{sub S}{sup 0}} = -0.71{sub -0.32}{sup +0.38} {+-} 0.04 and C{sub 3K{sub S}{sup 0}} = -0.34{sub -0.25}{sup +0.28} {+-} 0.05. Fixing C = 0 we measure the time-dependent CP asymmetry amplitude sin 2{beta} = -S{sub 3K{sub S}{sup 0}} = 0.79{sub -0.36}{sup +0.39} {+-} 0.04. The value of sin 2{beta} is in agreement with Standard Model predictions.
Author: Haleh K. Hadavand
Publisher:
ISBN:
Category :
Languages : en
Pages : 170
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Book Description
In this dissertation, a measurement of CP-violating effects in decays of neutral B mesons is presented. The data sample for this measurement consists of about 272 million {Upsilon}(4S) {yields} B{bar B} decays collected between 1999 and 2004 with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider, located at the Stanford Linear Accelerator Center. One neutral B meson is fully reconstructed in the CP eigenstate B{sup 0} {yields} K{sub S}{sup 0} K{sub S}{sup 0} K{sub S}{sup 0}. The other B meson is determined to be either a B{sup 0} or a {bar B}{sup 0}, at the time of its decay, from the properties of its decay products. The proper time {Delta}t elapsed between the decay of the two mesons is determined by reconstructing their decay vertices, and by measuring the distance between them. A novel technique for determining the B vertex of the decay to the CP eigenstate B{sup 0} {yields} K{sub S}{sup 0} K{sub S}{sup 0} K{sub S}{sup 0} has been applied since the tracks in the final state do not originate from the B decay vertex. The time-dependent CP asymmetry amplitudes are determined by the distributions of {Delta}t in events with a reconstructed B meson in the CP eigenstate. The detector resolution and the b flavor tagging parameters are constrained by the {Delta}t distributions of events with a fully reconstructed flavor eigenstate. Because of the special topology of this decay, the detector resolution on {Delta}t must be checked for consistency with decays with tracks which originate from the B decay. From a maximum likelihood fit to the {Delta}t distributions of all selected events, the value of the CP violating asymmetries are measured to be S{sub 3K{sub S}{sup 0}} = -0.71{sub -0.32}{sup +0.38} {+-} 0.04 and C{sub 3K{sub S}{sup 0}} = -0.34{sub -0.25}{sup +0.28} {+-} 0.05. Fixing C = 0 we measure the time-dependent CP asymmetry amplitude sin 2{beta} = -S{sub 3K{sub S}{sup 0}} = 0.79{sub -0.36}{sup +0.39} {+-} 0.04. The value of sin 2{beta} is in agreement with Standard Model predictions.
Author: Joshua M. Thompson
Publisher:
ISBN:
Category :
Languages : en
Pages : 182
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Author: Morris Nicholas Danielson
Publisher:
ISBN:
Category :
Languages : en
Pages : 286
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Author: Ran Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 258
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Author: Mauro Savrié
Publisher:
ISBN:
Category : CP violation (Nuclear physics)
Languages : en
Pages : 384
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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This dissertation presents a measurement of CP asymmetries and branching fractions for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 88 million?(4S) → B{bar B} decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory located at the Stanford Linear Accelerator Center. A fit to kinematic, topological, and particle identification information measures the charge-averaged branching fractions?(B° →??−) = (4.7 ± 0.6 ± 0.2) x 10−6 and?(B° → K+?−) = (17.9 ± 0.9 ± 0.7) x 10−6; the 90% confidence level upper limit?(B° → K+K−)
Author:
Publisher:
ISBN:
Category : Nuclear physics
Languages : en
Pages : 388
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Author: Markus Röhrken
Publisher: Springer Science & Business Media
ISBN: 3319007262
Category : Science
Languages : en
Pages : 205
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This thesis describes a high-quality, high-precision method for the data analysis of an interesting elementary particle reaction. The data was collected at the Japanese B-meson factory KEKB with the Belle detector, one of the most successful large-scale experiments worldwide. CP violation is a subtle quantum effect that makes the world look different when simultaneously left and right and matter and antimatter are exchanged. This being a prerequisite for our own world to have developed from the big bang, there are only a few experimental indications of such effects, and their detection requires very intricate techniques. The discovery of CP violation in B meson decays garnered Kobayashi and Maskawa, who had predicted these findings as early as 1973, the 2008 Nobel prize in physics. This thesis describes in great detail what are by far the best measurements of branching ratios and CP violation parameters in two special reactions with two charm mesons in the final state. It presents an in-depth but accessible overview of the theory, phenomenology, experimental setup, data collection, Monte Carlo simulations, (blind) statistical data analysis, and systematic uncertainty studies.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 208
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The Standard Model (SM) of particle physics successfully describes all of the observed interactions of the fundamental particles (with the exception of non-zero neutrino mass). Despite this enormous success, the SM is widely viewed as an incomplete theory. For example, the size of the asymmetry between matter and antimatter is not nearly large enough to account for the abundance of matter observed throughout the universe. It is thus believed that as-yet-unknown physical phenomena must exist that introduce new asymmetries between matter and antimatter. In this thesis, by studying decays that happen only rarely in the SM, we make measurements of asymmetries between matter and antimatter that are potentially sensitive to the existence of processes beyond the SM. At the PEP-II asymmetric-energy B Factory at SLAC, electrons and positrons are collided at the [Upsilon](4S) resonance to create pairs of B mesons. The BABAR detector is used to measure the subsequent decay products. Using 383 million [Upsilon](4S) 2!B$\bar{B}$ decays, we study the decay B0 2!K+K-K0. In the SM, this decay is dominated by loop amplitudes. Asymmetries between matter and antimatter (CP asymmetries) are extracted by measuring the time-dependence of the complex amplitudes describing the B0 and $\bar{B}$0 decays as functions of their kinematics. The interference between decays with and without the mixing of neutral B mesons allows for the measurement of the angle [beta]eff, which is a measure of CP violation. We also measure the direct CP asymmetry ACP. Data samples reconstructed from three K0 modes (KS0 2![pi]+[pi]-, KS0 2![pi]0[pi]0, and KL0) are fit simultaneously. They find ACP = -0.015 ± 0.077 ± 0.053 and [beta]eff = 0.352 ± 0.076 ± 0.026 rad, corresponding to a CP violation significance of 4.8[sigma]. A second solution near [pi]/2-[beta]eff is disfavored with a significance of 4.5[sigma]. In a subsequent fit to the region with mK+K-> 1.1 GeV/c2, they find ACP = -0.054 ± 0.102 ± 0.060 and [beta]eff = 0.436 ± 0.087-0.031+0.055 rad, excluding the possibility that [beta]eff = 0 at 5.1[sigma]. They use the data with msub K+K-
Author: Stephan Narison
Publisher:
ISBN:
Category : Particles (Nuclear physics)
Languages : en
Pages : 348
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