Measurement of Time-dependent CP Asymmetry in the Decay of a Neutral B Meson to a J/Psi and a Long-lived Neutral Kaon at BABAR PDF Download

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2009 2009

Measurement of Time-dependent CP Asymmetry in the Decay of a Neutral B Meson to a J/Psi and a Long-lived Neutral Kaon at BABAR

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

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Book Description
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.

Measurement of Time-dependent CP Asymmetry in the Decay of a Neutral B Meson to a J/Psi and a Long-lived Neutral Kaon at BABAR

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

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Measurement of Time-Dependent CP Asymmetry in the Decay of a Neutral B Meson to a J/Psi and a Long-Lived Neutral Kaon at BaBar

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

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Study of Time-dependent CP Asymmetries with Partial Reconstruction of B-]D*pi

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 27

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Book Description
The authors present a preliminary measurement of the time-dependent CP asymmetries in decays of neutral B mesons to the final states D*{sup {-+}}[pi]{sup ±}, using approximately 82 million B{bar B} events collected by the BABAR experiment at the PEP-II storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high momentum [pi]{sup ±} and the low momentum pion from the D*{sup {-+}} decay are reconstructed. The flavor of the other B meson in the event is tagged using the information from kaon and lepton candidates. They measure the time-dependent CP asymmetry [Alpha] = -0.063 {+-} 0.024 (stat.) {+-} 0.017 (syst.). They interpret these results in terms of the angles of the unitarity triangle to set a bound on

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).

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.

Update of Time-Dependent CP Asymmetry Measurements in B to C-cbar-s Decays

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 19

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We present updated measurements of time-dependent CP asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465 ± 5) x 106 [Upsilon](4S) → B{bar B} decays collected with the BABAR detector at the PEP-II B factory. The time-dependent CP asymmetry parameters measured from J/[psi]K{sub S}°, J/[psi]K{sub L}°, [psi](2S)K{sub S}°, [chi]{sub c1}K{sub S}°, [eta]{sub c}K{sub S}°, and J/[psi]K*° decays are: (1) C{sub f} = 0.026 ± 0.020(stat) ± 0.016(syst); and (2) S{sub f} = 0.691 ± 0.029(stat) ± 0.014(syst).

Measurement of Time-Dependent CP Asymmetry in B0-]ccbar K(*)0 Decays

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15

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Book Description
The authors present updated measurements of time-dependent Cp asymmetries in fully reconstructed neutral B decays containing a charmonium meson. The measurements reported here use a data sample of (465 ± 5) x 106 [Upsilon](4S) 2!B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric energy ee− storage rings operating at the SLAC National Accelerator Laboratory. The time-dependent CP asymmetry parameters measured from J/[psi] K{sub S}°, J/[psi]K{sub L}°, [psi](2S)K{sub S}°, [eta]{sub c}K{sub S}°, [chi]{sub c1}K{sub S}° and J/[psi] K*(892)° decays are: C{sub f} = 0.024 ± 0.020(stat) ± 0.016(syst) and -[eta]{sub f}S{sub f} = 0.687 ± 0.028(stat) ± 0.012(syst).

BRANCHING FRACTION AND TIME-DEPENDENT CP ASYMMETRY IN NEUTRAL B DECAYS TO PSI AND A NEUTRAL PION.

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

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Book Description
The invariance of physical laws under the combination of exchange of particles with antiparticles (charge conjugation, C) and reversal of coordinates (parity, P) is called CP symmetry. The violation of CP symmetry was first discovered in 1964 in the neutral kaon system, and is in general one of the great puzzles of particle physics. The recent observation of CP violation in the B meson system has been a simultaneous success for model predictions and experiment. The opportunity now exists to probe details of the underlying mechanisms. This thesis presents measurements of the branching fraction and time-dependent CP-violating asymmetry in neutral B decays to J/[psi][pi][sup 0]. The decay amplitude for this channel features both tree and penguin diagram contributions, the interference of which can yield a result for the asymmetry differing from that found in the ''golden mode'' B[sup 0][yields] J/[psi] K[sub s][sup 0]. Using the measured branching fraction and CP asymmetry, constraints are placed on the ratio of penguin to tree amplitudes in B[sup 0][yields] J/[psi][pi][sup 0]. In addition, the impact on the CP asymmetry measurement in B[sup 0][yields] J/[psi] K[sub s][sup 0] is discussed. The results are presented for e[sup+]e[sup -] annihilation data collected with the BABAR detector on the[Upsilon](4S) resonance at the PEP-II asymmetric-energy B Factory at SLAC. The measurement of the branching fraction, based on about 23 million B[bar B] pairs collected between October 1999 and October 2000, yields BF(B[sup 0][yields] J/[psi][pi][sup 0])= (2.0[+-] 0.6 (stat)[+-] 0.2(syst)) x 10[sup -5]. With about 88 million B[bar B] pairs collected during the years 1999-2002, our results for the coefficients of the cosine and sine terms of the CP asymmetry are C[sub J/[psi][pi][sup 0]]= 0.38[+-] 0.41 (stat)[+-] 0.09 (syst) and S[sub J/[psi][pi][sup 0]]= 0.05[+-] 0.49 (stat)[+-] 0.16 (syst).

Measurement of the Time-Dependent CP Asymmetry in the B0-]Phi K0 Decay

Author:
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ISBN:
Category :
Languages : en
Pages : 7

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The authors present a measurement of the time-dependent CP asymmetry for the neutral B-meson decay B° →? K°. They use a sample of approximately 114 million B-meson pairs taken at the?(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct the CP eigenstates?K{sub S}° and?K{sub L}° where? → KK−, K{sub S}° →?+?−, and K{sub L}° is observed via its hadronic interactions. The other B meson in the event is tagged as either a B° or {bar B}° from its decay products. The values of the CP-violation parameters are S{sub {phi}K} = 0.47 ± 0.34(stat){sub -0.06}{sup +0.08}(syst) and C{sub {phi}K} = 0.01 ± 0.33(stat) ± 0.10(syst).

The Measurement of Time-Dependent CP-Violating Asymmetries in Loop-Dominated B Decays with BABAR.

Author: A. Hoecker
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
We report on preliminary measurements of time-dependent CP asymmetries in neutral B decays to CP eigenstates with transition amplitudes that are dominated by penguin-type loops. The results are obtained from a data sample of up to 227 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson Factory at SLAC. The amplitudes of the effective mixing-induced CP asymmetries, sin2{beta}{sub eff}, are derived from decay-time distributions of events in which one neutral B meson is fully reconstructed in a final state without charm and the other B meson is determined to be either a B{sup 0} or {bar B}{sup 0} from its decay products.

A Study of Time-dependent CP-violating Asymmetries in B0-]J/psiK0S and B0-]psi(2S)K0S Decays

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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Book Description
We present a preliminary measurement of time-dependent CP-violating asymmetries in B° → J/[psi] K{sub S}° and B° → [psi](2S)K{sub S}° decays recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The data sample consists of 9.0 fb−1 collected at the [Upsilon](4S) resonance and 0.8 fb−1 off-resonance. One of the neutral B mesons, produced in pairs at the [Upsilon](4S), is fully reconstructed. The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The time difference between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities and the time resolution function are measured with samples of fully-reconstructed semileptonic and hadronic neutral B final states. The value of the asymmetry amplitude, sin2[beta], is determined from a maximum likelihood fit to the time distribution of 120 tagged B° → J/[psi] K{sub S}° and B° → [psi](2S) K{sub S}° candidates to be sin2[beta] = 0.12 ± 0.37(stat) ± 0.09(syst) (preliminary).