Updated Determination of D⁰–D¯⁰Mixing and CP Violation Parameters with D⁰→K⁺π⁻ Decays

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D⁰→K⁺π⁻ to D⁰→K⁻π⁺ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0  fb⁻¹ recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x′²=(3.9±2.7)×10⁻⁵, y′=(5.28±0.52)×10⁻³, and R[subscript D]=(3.454±0.031)×10⁻³. Without this assumption, the measurement is performed separately for D⁰ and D[over ¯]⁰ mesons, yielding a direct CP-violating asymmetry A[subscript D]=(-0.1±9.1)×10⁻³, and magnitude of the ratio of mixing parameters 1.00<|q/p|<1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed

Observation of D⁰ Meson Decays to Π⁺π⁻μ⁺μ⁻ and K⁺K⁻μ⁺μ⁻ Final States

The first observation of the D⁰→π⁺π⁻μ⁺μ⁻ and D⁰→K⁺K⁻μ⁺μ⁻ decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2  fb⁻¹ of integrated luminosity. The corresponding branching fractions are measured using as normalization the decay D⁰→K⁻π⁺[μ⁺μ⁻][subscript ρ⁰/ω], where the two muons are consistent with coming from the decay of a ρ⁰ or ω meson. The results are B(D⁰→π⁺π⁻μ⁺μ⁻)=(9.64±0.48±0.51±0.97)×10⁻⁷ and B(D⁰→K⁺K⁻μ⁺μ⁻)=(1.54±0.27±0.09±0.16)×10⁻⁷, where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalization branching fraction. The dependence of the branching fraction on the dimuon mass is also investigated

Updated determination of D 0 - D 0 mixing and C P violation parameters with D 0 → K + π -

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D0→K+π- to D0→K-π+ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0 fb-1 recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x′2=(3.9±2.7)×10-5, y′=(5.28±0.52)×10-3, and RD=(3.454±0.031)×10-3. Without this assumption, the measurement is performed separately for D0 and D0 mesons, yielding a direct CP-violating asymmetry AD=(-0.1±9.1)×10-3, and magnitude of the ratio of mixing parameters 1.00<|q/p|<1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed

Updated determination of D-0-(D)over-bar(0) mixing and CP violation parameters with D-0 -> K+ pi(-) decays

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of $D^0\to K^+\pi^-$ to $D^0\to K^-\pi^+$ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of $5.0$ fb$^{-1}$ recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be $x'^2=(3.9 \pm 2.7) \times10^{-5}$, $y'=(5.28 \pm 0.52) \times 10^{-3}$, and $R_D=(3.454 \pm 0.031)\times10^{-3}$. Without this assumption, the measurement is performed separately for $D^0$ and $\overline{D}{}^0$ mesons, yielding a direct CP-violating asymmetry $A_D =(-0.1\pm9.1)\times10^{-3}$, and magnitude of the ratio of mixing parameters $1.00< |q/p| <1.35$ at the $68.3\%$ confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-046.htm

Measurement of CP observables in B± → D(⁎)K± and B± → D(⁎)π± decays

Measurements of CP observables in B± → D(∗)K ± and B± → D(∗) π± decays are presented, where D(∗) indicates a neutral D or D∗ meson that is an admixture of D(∗)0 and D¯ (∗)0 states. Decays of the D∗ meson to the Dπ0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K ±π∓, K + K − and π+π− final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb−1 taken at centre-of-mass energies of √s = 7, 8 and 13 TeV, respectively. The study of B± → D∗K ± and B± → D∗π± decays using a partial reconstruction method is the first of its kind, while the measurement of B± → D K ± and B± → Dπ± decays is an update of previous LHCb measurements. The B± → D K ± results are the most precise to date

Measurement of the B ± production cross-section in pp collisions at √{s}=7 and 13 TeV

The production of B ± mesons is studied in pp collisions at centre-of-mass energies of 7 and 13 TeV, using B ± → J/ ψ K ± decays and data samples corresponding to 1.0 fb-1 and 0.3 fb-1, respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range 0 < p T < 40 GeV/ c and the rapidity range 2.0 < y < 4.5 are measured to be σ ( pp\to {B}^{± }X,√{s}=7 TeV)=43.0± 0.2± 2.5± 1.7 μ b, σ ( pp\to {B}^{± }X,√{s}=13 TeV)=86.6± 0.5± 5.4± 3.4 μ b, where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the B ± → J/ ψ K ± branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be 2.02 ± 0.02 (stat) ± 0.12 (syst). Differential cross-sections are also reported as functions of p T and y. All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamic

Search for the rare decays B0 → J=ψγ and B0s → J=ψγ

A search for the rare decay of a B0 or Bs0 meson into the final state J/ψγ is performed, using data collected by the LHCb experiment in pp collisions at s=7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than 1.5×10-6 for the B0→J/ψγ decay mode are excluded at 90% confidence level. For the Bs0→J/ψγ decay mode, branching fraction values larger than 7.3×10-6 are excluded at 90% confidence level; this is the first branching fraction limit for this decay

Search for the rare decays B0 → J=ψγ and B0s → J=ψγ

A search for the rare decay of a B0 or Bs0 meson into the final state J/ψγ is performed, using data collected by the LHCb experiment in pp collisions at s=7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than 1.5×10-6 for the B0→J/ψγ decay mode are excluded at 90% confidence level. For the Bs0→J/ψγ decay mode, branching fraction values larger than 7.3×10-6 are excluded at 90% confidence level; this is the first branching fraction limit for this decay

Updated determination of D

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of $D^0\to K^+\pi^-$ to $D^0\to K^-\pi^+$ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of $5.0$ fb$^{-1}$ recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be $x'^2=(3.9 \pm 2.7) \times10^{-5}$, $y'=(5.28 \pm 0.52) \times 10^{-3}$, and $R_D=(3.454 \pm 0.031)\times10^{-3}$. Without this assumption, the measurement is performed separately for $D^0$ and $\overline{D}{}^0$ mesons, yielding a direct CP-violating asymmetry $A_D =(-0.1\pm9.1)\times10^{-3}$, and magnitude of the ratio of mixing parameters $1.00< |q/p| <1.35$ at the $68.3\%$ confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-046.htm