The CPLEAR experiment at CERN has directly studied matter and antimatter symmetries via the measu... more The CPLEAR experiment at CERN has directly studied matter and antimatter symmetries via the measurement of the time evolution of K0 and K0. The CPT violation parameter Re(delta) was directly measured with a precision of a few 10-4 while Im(delta) is determined from the Bell-Steinberger relation, with a precision of 10-5. The mass and decay-width equality between the K0 and
A measurement of the ratio of the branching fractions of the B + → K + µ + µ − and B + → K + e + ... more A measurement of the ratio of the branching fractions of the B + → K + µ + µ − and B + → K + e + e − decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb −1 , recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q 2 < 6 GeV 2 /c 4 is measured to be 0.745 +0.090 −0.074 (stat) ± 0.036 (syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the SM prediction within 2.6 standard deviations.
Measurement of the fraction of Υ (1S) originating from χ b (1P ) decays in pp collisions at √ s =... more Measurement of the fraction of Υ (1S) originating from χ b (1P ) decays in pp collisions at √ s = 7 TeV
ABSTRACT A search for CP violation in the phase-space structures of D0 and D0bar decays to the fi... more ABSTRACT A search for CP violation in the phase-space structures of D0 and D0bar decays to the final states K-K+pi-pi+ and pi-pi+pi+pi- is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0fb^-1 collected in 2011 by the LHCb experiment in $pp$ collisions at a centre-of-mass energy of 7TeV. For the K-K+pi-pi+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the pi-pi+pi+pi- final state is partitioned into 128 bins, each bin with approximately 2500 decays. The $p$-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity.
The first observation of the decay B 0 s → K * 0 K * 0 is reported using 35 pb −1 of data collect... more The first observation of the decay B 0 s → K * 0 K * 0 is reported using 35 pb −1 of data collected by LHCb in proton-proton collisions at a centre-of-mass energy of 7 TeV. A total of 49.8 ± 7.5 signal events are observed, with a significance of 10.9 σ. The branching fraction and the CP -averaged K * 0 longitudinal polarization fraction are measured to be B B 0 s → K * 0 K * 0 = (2.81 ± 0.46(stat.) ± 0.45(syst.) ± 0.34 (f s /f d )) × 10 −5 and f L = 0.31 ± 0.12(stat.) ± 0.04(syst.).
A study of indirect CP violation in D 0 mesons through the determination of the parameter AΓ is p... more A study of indirect CP violation in D 0 mesons through the determination of the parameter AΓ is presented using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb −1 , collected with the LHCb detector and recorded at the centre-of-mass energy of 7 TeV at the LHC. The parameter AΓ is the asymmetry of the effective lifetimes measured in decays of D 0 and D 0 mesons to the CP eigenstates K − K + and π − π + . Fits to the data sample yield AΓ(KK) = (−0.35 ± 0.62 ± 0.12) × 10 −3 and AΓ(ππ) = (0.33 ± 1.06 ± 0.14) × 10 −3 , where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in AΓ between the two final states and no indication of CP violation.
We present branching fraction and CP asymmetry measurements as well as angular studies of B → φφK... more We present branching fraction and CP asymmetry measurements as well as angular studies of B → φφK decays using 464 × 10 6 BB events collected by the BABAR experiment. The branching fractions are measured in the φφ invariant mass range below the ηc resonance (m φφ < 2.85 GeV). We find B(B + → φφK + ) = (5.6 ± 0.5 ± 0.3) × 10 −6 and B(B 0 → φφK 0 ) = (4.5 ± 0.8 ± 0.3) × 10 −6 , where the first uncertaintiy is statistical and the second systematic. The measured direct CP asymmetries for the B ± decays are ACP = −0.10 ± 0.08 ± 0.02 below the ηc threshold (m φφ < 2.85 GeV) and ACP = 0.09 ± 0.10 ± 0.02 in the ηc resonance region (m φφ in [2.94,3.02] GeV). Angular distributions are consistent with J P = 0 − in the ηc resonance region and favor J P = 0 + below the ηc resonance.
... P R. Barbosa Marinho, I. Bediaga, G. Cernicchiaro, A. Franca Barbosa, J. Magnin, J. Marques d... more ... P R. Barbosa Marinho, I. Bediaga, G. Cernicchiaro, A. Franca Barbosa, J. Magnin, J. Marques de Miranda, A. Massafferri, A. Reis, R. Silva, S. Amato, P. Colrain, T. Da Silva, JR T. De Mello-Neto, L. De Paula, M. Gandelman, J H. Lopes, B. Marechal, D. Moraes, E. Polycarpo, Z ...
The CPLEAR experiment at CERN has directly studied matter and antimatter symmetries via the measu... more The CPLEAR experiment at CERN has directly studied matter and antimatter symmetries via the measurement of the time evolution of K0 and K0. The CPT violation parameter Re(delta) was directly measured with a precision of a few 10-4 while Im(delta) is determined from the Bell-Steinberger relation, with a precision of 10-5. The mass and decay-width equality between the K0 and
A measurement of the ratio of the branching fractions of the B + → K + µ + µ − and B + → K + e + ... more A measurement of the ratio of the branching fractions of the B + → K + µ + µ − and B + → K + e + e − decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb −1 , recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q 2 < 6 GeV 2 /c 4 is measured to be 0.745 +0.090 −0.074 (stat) ± 0.036 (syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the SM prediction within 2.6 standard deviations.
Measurement of the fraction of Υ (1S) originating from χ b (1P ) decays in pp collisions at √ s =... more Measurement of the fraction of Υ (1S) originating from χ b (1P ) decays in pp collisions at √ s = 7 TeV
ABSTRACT A search for CP violation in the phase-space structures of D0 and D0bar decays to the fi... more ABSTRACT A search for CP violation in the phase-space structures of D0 and D0bar decays to the final states K-K+pi-pi+ and pi-pi+pi+pi- is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0fb^-1 collected in 2011 by the LHCb experiment in $pp$ collisions at a centre-of-mass energy of 7TeV. For the K-K+pi-pi+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the pi-pi+pi+pi- final state is partitioned into 128 bins, each bin with approximately 2500 decays. The $p$-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity.
The first observation of the decay B 0 s → K * 0 K * 0 is reported using 35 pb −1 of data collect... more The first observation of the decay B 0 s → K * 0 K * 0 is reported using 35 pb −1 of data collected by LHCb in proton-proton collisions at a centre-of-mass energy of 7 TeV. A total of 49.8 ± 7.5 signal events are observed, with a significance of 10.9 σ. The branching fraction and the CP -averaged K * 0 longitudinal polarization fraction are measured to be B B 0 s → K * 0 K * 0 = (2.81 ± 0.46(stat.) ± 0.45(syst.) ± 0.34 (f s /f d )) × 10 −5 and f L = 0.31 ± 0.12(stat.) ± 0.04(syst.).
A study of indirect CP violation in D 0 mesons through the determination of the parameter AΓ is p... more A study of indirect CP violation in D 0 mesons through the determination of the parameter AΓ is presented using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb −1 , collected with the LHCb detector and recorded at the centre-of-mass energy of 7 TeV at the LHC. The parameter AΓ is the asymmetry of the effective lifetimes measured in decays of D 0 and D 0 mesons to the CP eigenstates K − K + and π − π + . Fits to the data sample yield AΓ(KK) = (−0.35 ± 0.62 ± 0.12) × 10 −3 and AΓ(ππ) = (0.33 ± 1.06 ± 0.14) × 10 −3 , where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in AΓ between the two final states and no indication of CP violation.
We present branching fraction and CP asymmetry measurements as well as angular studies of B → φφK... more We present branching fraction and CP asymmetry measurements as well as angular studies of B → φφK decays using 464 × 10 6 BB events collected by the BABAR experiment. The branching fractions are measured in the φφ invariant mass range below the ηc resonance (m φφ < 2.85 GeV). We find B(B + → φφK + ) = (5.6 ± 0.5 ± 0.3) × 10 −6 and B(B 0 → φφK 0 ) = (4.5 ± 0.8 ± 0.3) × 10 −6 , where the first uncertaintiy is statistical and the second systematic. The measured direct CP asymmetries for the B ± decays are ACP = −0.10 ± 0.08 ± 0.02 below the ηc threshold (m φφ < 2.85 GeV) and ACP = 0.09 ± 0.10 ± 0.02 in the ηc resonance region (m φφ in [2.94,3.02] GeV). Angular distributions are consistent with J P = 0 − in the ηc resonance region and favor J P = 0 + below the ηc resonance.
... P R. Barbosa Marinho, I. Bediaga, G. Cernicchiaro, A. Franca Barbosa, J. Magnin, J. Marques d... more ... P R. Barbosa Marinho, I. Bediaga, G. Cernicchiaro, A. Franca Barbosa, J. Magnin, J. Marques de Miranda, A. Massafferri, A. Reis, R. Silva, S. Amato, P. Colrain, T. Da Silva, JR T. De Mello-Neto, L. De Paula, M. Gandelman, J H. Lopes, B. Marechal, D. Moraes, E. Polycarpo, Z ...
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