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Languages : en
Pages : 5

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We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23 million [Upsilon](4S) → B{bar B} decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events where one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2[beta], is derived from the decay time distributions in such events. The result is sin2[beta] = 0.34 ± 0.20 (stat) ± 0.05 (syst).

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Languages : en
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We present updated results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 62 million [Upsilon](4S) [yields] B[bar B] decays collected between 1999 and 2001 by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. In this sample we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2[beta], is derived from the decay time distributions in such events. We measure sin2[beta] = 0.75 [+-] 0.09 (stat) [+-] 0.04 (syst) and lambda = 0.92 [+-] 0.06 (stat) [+-] 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary.

Author:
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Languages : en
Pages : 256

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This dissertation presents a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data sample consists of about 88 million [Upsilon](4S) 2!B{bar B} decays collected between 1999 and 2002. We study events in which one neutral B meson decay to the CP-eigenstates J/[psi] K{sub S}°, [psi](2S)K{sub S}°, [chi]{sub c1}K{sub S}°, and [eta]{sub c}K{sub S}°, or to flavor-eigenstates involving D{sup (*)}[pi]/[rho]/a1 and J/[psi]K*°(K*° 2!K [pi]−), is fully reconstructed. The flavor of the other neutral B meson is tagged at the time of its decay, mainly using the charge of identified leptons and kaons. The proper time elapsed between the meson decays is determined by measuring the distance between the decay vertices. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2[beta], is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor- and CP-eigenstate samples. We measure sin2[beta] = 0.755 ± 0.074 (stat) ± 0.030 (syst).

Author: Thomas E Browder
Publisher: World Scientific
ISBN: 9814602760
Category :
Languages : en
Pages : 528

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CP violation is one of the most subtle effects in the Standard Model of particle physics and may be the first clue to the physics that lies beyond. Charge conjugation, C, and parity, P, are symmetries of particle interactions. C corresponds to the operation of replacing a particle by its antiparticle, while P is the operation of mirror reflection. Before 1956, it was believed that these were also symmetries of the interactions of elementary particles. In 1956, C S Wu found evidence for P violation in the weak interaction. Theorists proposed that the combination of CP would be a symmetry of the weak interaction. In 1964, Christenson, Cronin, Fitch and Turlay found the first evidence for the violation of CP symmetry in the decays of kaons.Although Kobayashi and Maskawa then showed how the Standard Model can accommodate the observed CP violation, Wolfenstein pointed out that it is also possible that there is a new interaction in addition to the usual four, called the superweak interaction, which is responsible for the asymmetry. To test this idea, the observation of a different type of asymmetry, called direct CP violation, is required; in the kaon sector, very precise measurements of the ratio of kaon decay rates are necessary. In B decay modes where a second order weak process whimisically named “penguin” interferes with another suppressed, first order “tree” amplitude, it may also be possible to observe these direct CP-violating effects.B physics and CP violation is now one of the major growth areas in high energy physics. Nearly every major high energy physics laboratory now has a project underway to observe the large CP asymmetries expected in the B sector and to test the consistency of the Standard Model. The unitarity of the Kobayashi-Maskawa mixing matrix in the Standard Model implies the existence of three phases, called alpha, beta and gamma, which can be determined by the measurements of CP asymmetries in B decays. About 200 participants gathered in Hawaii in March 1997 to discuss the progress in the field, and this important book constitutes the proceedings of that conference.

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Languages : en
Pages : 5

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Book Description
We present results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 million [Upsilon](4S) → B{bar B} decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B° or {bar B}° from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2[beta], is derived from the decay-time distributions in such events. We measure sin2[beta] = 0.741 ± 0.067 (stat) ± 0.033 (syst) and.

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Languages : en
Pages : 5

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We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S and C in neutral B decays to the [pi]{sup +-}[pi] CP eigenstate, and an updated preliminary measurement of the charge asymmetry in B 2!K{sup ±}[pi] decays. Event yields and CP-violation parameters are determined simultaneously from a multidimensional unbinned maximum likelihood fit. In a data sample consisting of approximately 33 million [Upsilon](4S) 2!B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 6511{sup +12} [pi]{sup +-}[pi] and 217 ± 18 K{sup ±}[pi] candidates and measure S = 0.030{sup +0} ± 0.11, C = -0.25−0{sup +0} = -0.25−0{sup +0} ± 0.14, and = -0.07 {+-} 0.08 {+-} 0.02, where the first error is statistical and the second is systematic.

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: Ran Liu
Publisher:
ISBN:
Category :
Languages : en
Pages : 258

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Author: Michael Prim
Publisher: Springer Science & Business Media
ISBN: 3319057561
Category : Science
Languages : en
Pages : 111

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This thesis describes the thorough analysis of the rare B meson decay into φ K* on data taken by the Belle Collaboration at the B-meson-factory KEKB over 10 years. This reaction is very interesting, because it in principle allows the observation of CP-violation effects. In the Standard Model however, no CP violation in this reaction is expected. An observation of CP asymmetries thus immediately implies new physics. This thesis presents an amplitude analysis of this decay and the search for CP violation in detail and discusses methods to solve related problems: The quantification of multivariate dependence and the improvement of numeric evaluation speed of normalization integrals in amplitude analysis. In addition it provides an overview of the theory, experimental setup, (blind) statistical data analysis and estimation of systematic uncertainties.

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Languages : en
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We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S and C in neutral B decays to the[pi][sup+-][pi] CP eigenstate, and an updated preliminary measurement of the charge asymmetry in B[yields] K[sup[+-]][pi] decays. Event yields and CP-violation parameters are determined simultaneously from a multidimensional unbinned maximum likelihood fit. In a data sample consisting of approximately 33 million[Upsilon](4S)[yields] B[bar B] decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 65[sub -11][sup+12][pi][sup+-][pi] and 217[+-] 18 K[sup[+-]][pi] candidates and measure S= 0.03[sub -0][sup+0][+-] 0.11, C= -0.25[sub -0][sup+0]= -0.25[sub -0][sup+0][+-] 0.14, and= -0.07[+-] 0.08[+-] 0.02, where the first error is statistical and the second is systematic.