Author:
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Category :
Languages : en
Pages : 10

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Author:
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Category :
Languages : en
Pages :

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We measure the time-dependent CP asymmetry parameters in B° 2!KK−K° based on a data sample of approximately 227 million B-meson pairs recorded at the [Upsilon](4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. We reconstruct two-body B° decays to [phi](1020)K{sub s}° and [phi](1020)K{sub L}°, and the three-body decay KK−K{sub s}° with [phi](1020)K{sub s}° excluded. For the B° 2![phi]K° decays, they measure sin 2[beta]{sub eff}([phi]K°) = +0.50 ± 0.25(stat){sub -0.04}{sup +0.07}(syst). The B° 2!K+K−K{sub s}° decays are dominated by K+K− S-wave, as determined from an angular analysis; they measure sin 2[beta]{sub eff} (K+K−K{sub s}°) = +0.55 ± 0.22(stat) ± 0.04(syst) ± 0.11(CP), where the last error is due to the uncertainty in the fraction of CP-even contributions to the decay amplitude. We find no evidence for direct CP violation.

Author: Paul E. Kutter
Publisher:
ISBN:
Category :
Languages : en
Pages : 4

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The authors present results on time-dependent CP asymmetries in f{sub 0}(980)({yields} {pi}{sup +}{pi}{sup -})K{sub S}{sup 0} and B{sup 0} {yields} K{sup +}K{sup -}K{sup 0}. The measurements use a data sample consisting of approximately 209(f{sub 0}(980)({yields} {pi}{sup +}{pi}{sup -})K{sub S}{sup 0}) and 227(B{sup 0} {yields} K{sup +}K{sup -}K{sup 0}) million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 355

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In this work we presented measurements of CP violation and decay rates of B decays in final states not involving a charm quark in the final state. In particular, the time-dependent CP asymmetries of decays which proceed through b 2!s elementary transition is a particularly sensitive probe of physics beyond the Standard Model. In fact, even if the precise measurements of CP conserving and CP violating processes show the success of the CKM picture of the flavour physics, the sector of b 2!s transitions is still not strongly constrained and leaves room for new physics contributions. In particular, we considered the decays which have the cleanest theoretical prediction within the Standard Model: B° 2![phi]K° and B° 2!K{sub s}°K{sub s}°K{sub s}° [beta]{sub eff}{sup SM} = 0.379. We examined the former with a completely new approach with respect to the past: the study of CP violation in the whole KK−K° phase space through a time-dependent Dalitz plot analysis. With this approach, we simultaneously measured the CP-violating asymmetries of the [phi]KJ°, f0(980)K° resonant and KK−K° non-resonant contributions, avoiding one of the largest uncertainties which affected the previous measurements of B° 2![phi]K°. We find [beta]{sub eff}(B° 2![phi]K°) = 0.06 ± 0.16 ± 0.05, which is lower than the Standard Model expectation, but it is consistent with it within two standard deviations. Moreover, only a recently developed experimental technique, which allows the determination of the position of B decay vertex when no charged tracks are originating from it, has made possible the measurement of the time-dependent CP asymmetry in B° 2!K{sub s}°K{sub s}°K{sub s}° decays. The mixing-induced CP parameter S in the Standard Model should be equal to sin 2[beta] parameter, which is measured with high precision in B 2![c{bar c}]K° decays by the B-factories. This statement is true, in the Standard Model, with excellent approximation for the decays studied in this work. The summary of the measurements in the b 2!s sector is shown in Fig. 9.8 A naive average of the b 2!s penguins, which does not account for the correlations existing among [phi]K°, f0(980)K° and K+K−K°, and that includes also modes with larger theoretical uncertainties, shows that -[eta]{sub CP} x S is lower than sin 2[beta]. This is not an evidence of physics beyond the Standard Model, but the systematic deviation from the expected value is an hint that there is room for it. More compelling evidence for new physics could be obtained measuring significant deviation in each decay channel from Standard Model prediction. Currently all the measurement are statistically limited and therefore an increase in accumulated statistics will shed more light into this quest for New Physics.

Author:
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Category :
Languages : en
Pages :

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The authors present a preliminary measurement of the time-dependent CP asymmetry for the neutral B-meson decay B[sup 0] --> [phi]K[sup 0]. They use a sample of approximately 227 million B-meson pairs recorded at the [Upsilon](4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct the CP eigenstates [phi]K[sub s][sup 0] and [phi]K[sub L][sup 0] where [phi] --> K[sup +]K[sup -], K[sub s][sup 0] --> [pi][sup +][pi][sup -], and K[sub L][sup 0] is observed via its hadronic interactions. The other B meson in the event is tagged as either a B[sup 0] or [bar B][sup 0] from its decay products. The values of the CP-violation parameters deived from the combined [phi]K[sup 0] dataset are S[sub [phi]K] = +0.50 [+-] 0.25(stat.)[sub -0.04][sup +0.07](syst.) and C[sub [phi]K] = 0.00 [+-] 0.23(stat.) [+-]0.05(syst.). In addition, the authors measure the CP-violating charge asymmetry A[sub CP](B[sup +] --> [phi]K[sup +]) = 0.054 [+-] 0.056(stat.) [+-] 0.012(syst.). All results are preliminary.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 18

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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: Emilie Claire Mutsumi Martin
Publisher:
ISBN: 9781109109634
Category :
Languages : en
Pages : 358

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The BABAR experiment at the SLAC National Accelerator Laboratory provides an excellent environment to study CP violation in B decays. A measurement of time-dependent CP-violating asymmetry in neutral B decays to charmonium states, in particular B0, B¯ 0 → J/psi K0L , is presented here. J/psi K0L is the most compelling CP-even final state used to measure the Unitarity Triangle parameter sin2beta at BABAR. The measurements reported here use a data sample of (465 +/- 5) million Upsilon(4 S) → BB¯ decays collected with the BABAR detector at the PEP-II asymmetric energy e +e- storage operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured for the B0 → J/psi K0L decay are: C = -0.033 +/- 0.050(stat) +/- 0.027(syst) and S = -0.694 +/- 0.061(stat) +/- 0.031(syst). These results are in good agreement with the Standard Model predictions.

Author: J. C. Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 19

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The authors present preliminary measurements of the Cp asymmetry parameters and CP content in B{sup 0} {yields} K{sup +}K{sup -}K{sub L}{sup 0} decays, with B{sup 0} {yields} {phi}K{sub L}{sup 0} events excluded. In a sample of 227 M B{bar B} pairs collected by the BABAR detector at the PEP-II B Factory at SLAC, they find the CP parameters to be S = 0.07 {+-} 0.28(stat){sub -0.12}{sup +0.11}(syst); C = 0.54 {+-} 0.22(stat){sub -0.09}{sup +0.08}(syst) where the first error is statistical and the second is systematic. Estimating the fraction of CP-odd final states from angular moments analysis in the K{sup +}K{sup -}K{sub S}{sup 0} CP-conjugate final state, f{sub odd}(K{sup +}K{sup -}K{sub L}{sup 0}) = 0.92 {+-} 0.07(stat) {+-} 0.06(syst), they determine sin2{beta}{sub eff} = 0.09 {+-} 0.33(stat){sub -0.14}{sup +0.13}(syst) {+-} 0.10(syst CP-cont) where the last error is due to uncertainty on the CP content.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 200

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