Papers by Giulio Auriemma
Physical Review Letters
We present a measurement of the CP-violating weak mixing phase ϕ_{s} using the decay B[over ¯]_{s... more We present a measurement of the CP-violating weak mixing phase ϕ_{s} using the decay B[over ¯]_{s}^{0}→D_{s}^{+}D_{s}^{-} in a data sample corresponding to 3.0 fb^{-1} of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint |λ|=1 to allow for the presence of CP violation in decay, yields ϕ_{s}=0.02±0.17(stat)±0.02(syst) rad, |λ|=0.91_{-0.15}^{+0.18}(stat)±0.02(syst). This result is consistent with the standard model expectation.
Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ a... more Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $\overline{B}{}^0$ mesons to the $J/\psi K^0_S$ final state. The data sample corresponds to an integrated luminosity of $3.0\,\text{fb}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8\,\text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $\overline{B}{}^0$ decays yields $S = 0.731 \pm 0.035 \, \text{(stat)} \pm 0.020 \,\text{(syst)}$ and $C = -0.038 \pm 0.032 \, \text{(stat)} \pm 0.005\,\text{(syst)}$. In the Standard Model, $S$ equals $\sin(2\beta)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.
A search for the decay $B^0_s\rightarrow J/\psi K^{*0}$ with $K^{*0} \rightarrow K^-\pi^+$ is per... more A search for the decay $B^0_s\rightarrow J/\psi K^{*0}$ with $K^{*0} \rightarrow K^-\pi^+$ is performed with 0.37 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 7 TeV collected by the LHCb experiment, finding a $\Bs \to J\psi K^-\pi^+$ peak of $114 \pm 11$ signal events. The $K^-\pi^+$ mass spectrum of the candidates in the $B^0_s$ peak is dominated by the $K^{*0}$ contribution. Subtracting the non-resonant $K^-\pi^+$ component, the branching fraction of \BsJpsiKst is $(4.4_{-0.4}^{+0.5} \pm 0.8) \times 10^{-5}$, where the first uncertainty is statistical and the second systematic. A fit to the angular distribution of the decay products yields the \Kst polarization fractions $f_L = 0.50 \pm 0.08 \pm 0.02$ and $f_{||} = 0.19^{+0.10}_{-0.08} \pm 0.02$.
Journal of High Energy Physics
A search for charmless three-body decays of B0 and B0s mesons with a K0S meson in the final state... more A search for charmless three-body decays of B0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)->K0Sh+h′- decay modes (h(′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported.
![Research paper thumbnail of Measurement of D^{0}-D[over ¯]^{0} Mixing Parameters and Search for CP Violation Using D^{0}→K^{+}π^{-} Decays](https://a.academia-assets.com/images/blank-paper.jpg)
Physical Review Letters
Measurements of charm mixing parameters from the decay-time-dependent ratio of D^{0}→K^{+}π^{-} t... more Measurements of charm mixing parameters from the decay-time-dependent ratio of D^{0}→K^{+}π^{-} to D^{0}→K^{-}π^{+} rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{-1} of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP ) symmetry, the mixing parameters are determined to be x^{'2}=(5.5±4.9)×10^{-5}, y^{'}=(4.8±1.0)×10^{-3}, and R_{D}=(3.568±0.066)×10^{-3}. Allowing for CP violation, the measurement is performed separately for D^{0} and D[over ¯]^{0} mesons yielding A_{D}=(-0.7±1.9)%, for the direct CP-violating asymmetry, and 0.75<|q/p|<1.24 at the 68.3% confidence level, for the parameter describing CP violation in mixing. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.
Physical review letters, Jan 13, 2015
Two structures are observed close to the kinematic threshold in the Ξ_{b}^{0}π^{-} mass spectrum ... more Two structures are observed close to the kinematic threshold in the Ξ_{b}^{0}π^{-} mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb^{-1}, recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity J^{P}=(1/2)^{+} and J^{P}=(3/2)^{+} states, denoted Ξ_{b}^{'-} and Ξ_{b}^{*-}. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ_{b}^{'-})-m(Ξ_{b}^{0})-m(π^{-})=3.653±0.018±0.006 MeV/c^{2}, m(Ξ_{b}^{*-})-m(Ξ_{b}^{0})-m(π^{-})=23.96±0.12±0.06 MeV/c^{2}, Γ(Ξ_{b}^{*-})=1.65±0.31±0.10 MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of…
Physical review letters, Jan 30, 2015
The semileptonic CP asymmetry in B^{0}-B[over ¯]^{0} mixing, a_{sl}^{d}, is measured in proton-pr... more The semileptonic CP asymmetry in B^{0}-B[over ¯]^{0} mixing, a_{sl}^{d}, is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb^{-1}, recorded by the LHCb experiment. Semileptonic B^{0} decays are reconstructed in the inclusive final states D^{-}μ^{+} and D^{*-}μ^{+}, where the D^{-} meson decays into the K^{+}π^{-}π^{-} final state and the D^{*-} meson into the D[over ¯]^{0}(→K^{+}π^{-})π^{-} final state. The asymmetry between the numbers of D^{(*)-}μ^{+} and D^{(*)+}μ^{-} decays is measured as a function of the decay time of the B^{0} mesons. The CP asymmetry is measured to be a_{sl}^{d}=(-0.02±0.19±0.30)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of a_{sl}^{d} to date and is consistent with the prediction from the standard model.
Physical Review Letters
We present a measurement of the ratio of the B[over ¯]_{s}^{0} meson lifetime, in the flavor-spec... more We present a measurement of the ratio of the B[over ¯]_{s}^{0} meson lifetime, in the flavor-specific decay to D_{s}^{+}π^{-}, to that of the B[over ¯]^{0} meson. The pp collision data used correspond to an integrated luminosity of 1 fb^{-1}, collected with the LHCb detector, at a center-of-mass energy of 7 TeV. Combining our measured value of 1.010±0.010±0.008 for this ratio with the known B[over ¯]^{0} lifetime, we determine the flavor-specific B[over ¯]_{s}^{0} lifetime to be τ(B[over ¯]_{s}^{0})=1.535±0.015±0.014 ps, where the uncertainties are statistical and systematic, respectively. This is the most precise measurement to date, and is consistent with previous measurements and theoretical predictions.
Physical Review D, 2012
A search for the X(4140) state in B + → J/ψφK + decays is performed with 0.37 fb −1 of pp collisi... more A search for the X(4140) state in B + → J/ψφK + decays is performed with 0.37 fb −1 of pp collisions at √ s = 7 TeV collected by the LHCb experiment. No evidence for this state is found, in 2.4 σ disagreement with a measurement by CDF. An upper limit on its production rate is set, B(B + → X(4140)K + ) × B(X(4140) → J/ψ φ)/B(B + → J/ψ φK + ) < 0.07 at 90% confidence level.
Physical Review Letters, 2014
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.
Nuclear Physics B, 2014
Evidence for the decay mode X(3872) → ψ(2S)γ in B + → X(3872)K + decays is found with a significa... more Evidence for the decay mode X(3872) → ψ(2S)γ in B + → X(3872)K + decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton-proton collisions, corresponding to an integrated luminosity of 3 fb −1 , collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872) → ψ(2S)γ decay to that of the X(3872) → J/ψ γ decay is measured to be
The Journal of High Energy Physics, 2014
Study of the kinematic dependences of Λ 0 b production in pp collisions and a measurement of the ... more Study of the kinematic dependences of Λ 0 b production in pp collisions and a measurement of the Λ 0 b → Λ + c π − branching fraction
JHEP, 2014
Decays of the form B 0 (s) → J/ψ K 0 S h + h ( )− (h ( ) = K, π) are searched for in protonproton... more Decays of the form B 0 (s) → J/ψ K 0 S h + h ( )− (h ( ) = K, π) are searched for in protonproton collision data corresponding to an integrated luminosity of 1.0 fb −1 recorded with the LHCb detector. The first observation of the B 0 s → J/ψ K 0 S K ± π ∓ decay is reported, with significance in excess of 10 standard deviations. The B 0 → J/ψ K 0 S K + K − decay is also observed for the first time. The branching fraction of B 0 → J/ψ K 0 S π + π − is determined, to significantly better precision than previous measurements, using B 0 → J/ψ K 0 S as a normalisation channel. Branching fractions and upper limits of the other B 0
Journal of Physics G-Nuclear and Particle Physics, 2014
A search is performed for the central exclusive production of pairs of charmonia produced in prot... more A search is performed for the central exclusive production of pairs of charmonia produced in proton-proton collisions. Using data corresponding to an integrated luminosity of 3 fb −1 collected at centre-of-mass energies of 7 and 8 TeV, J/ψJ/ψ and J/ψψ(2S) pairs are observed, which have been produced in the absence of any other activity inside the LHCb acceptance that is sensitive to charged particles in the pseudorapidity ranges (−3.5, −1.5) and (1.5, 5.0). Searches are also performed for pairs of P-wave charmonia and limits are set on their production. The cross-sections for these processes, where the dimeson system has a rapidity between 2.0 and 4.5, are measured to be σ J/ψ J/ψ = 58 ± 10(stat) ± 6(syst) pb, σ J/ψ ψ(2S) = 63 +27 −18 (stat) ± 10(syst) pb, σ ψ(2S)ψ(2S) < 237 pb, σ χ c0 χ c0 < 69 nb, σ χ c1 χ c1 < 45 pb, σ χ c2 χ c2 < 141 pb,
We report on measurements of the time-dependent CP violating observables in B 0 s → D ∓ s K ± dec... more We report on measurements of the time-dependent CP violating observables in B 0 s → D ∓ s K ± decays using a dataset corresponding to 1.0 fb −1 of pp collisions recorded with the LHCb detector. We find the CP violating observables C f = 0.53±0.25±0.04,
Measurement of the B 0 − B 0 and B 0 s − B 0 s production asymmetries in pp collisions at √ s = 7... more Measurement of the B 0 − B 0 and B 0 s − B 0 s production asymmetries in pp collisions at √ s = 7 TeV
Journal of High Energy Physics, 2014
First observations of the rare decays B + → K + π + π − µ + µ − and B + → φK + µ + µ − are presen... more First observations of the rare decays B + → K + π + π − µ + µ − and B + → φK + µ + µ − are presented using data corresponding to an integrated luminosity of 3.0 fb −1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The branching fractions of the decays are
Journal of High Energy Physics, 2012
The production of J/ψ mesons accompanied by open charm, and of pairs of open charm hadrons are ob... more The production of J/ψ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of 355 pb −1 collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured J/ψ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions.
Uploads
Papers by Giulio Auriemma