Quantum numbers of the X(3872)X(3872) state and orbital angular momentum in its ρ0Jψ\rho^0 J\psi decay

Angular correlations in $B^+\to X(3872) K^+$ decays, with $X(3872)\to \rho^0 J/\psi$, $\rho^0\to\pi^+\pi^-$ and $J/\psi \to\mu^+\mu^-$, are used to measure orbital angular momentum contributions and to determine the $J^{PC}$ value of the $X(3872)$ meson. The data correspond to an integrated luminosity of 3.0 fb$^{-1}$ of proton-proton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be $J^{PC}=1^{++}$. The $X(3872)$ is found to decay predominantly through S wave and an upper limit of $4\%$ at $95\%$ C.L. is set on the fraction of D wave.Comment: 16 pages, 4 figure

First direct mass measurements of stored neutron-rich 129,130,131Cd isotopes with FRS-ESR

A 410 MeV/u 238U projectile beam was used to create cadmium isotopes via abrasion-fission in a beryllium target placed at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated by the FRS and injected into the isochronous storage ring ESR for mass measurements. Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B\u3c1-tagging at the high-resolution central focal plane of the FRS. In the experiment with B\u3c1-tagging the magnetic rigidity of the injected fragments was determined with an accuracy of 2 c510-4. A new method of data analysis, which uses a correlation matrix for the combined data set from both experiments, has provided experimental mass values of 25 rare isotopes for the first time. The high sensitivity and selectivity of the method have given access to nuclides detected with a rate of a few atoms per week. In this letter we present for the 129,130,131Cd isotopes mass values directly measured for the first time. The experimental mass values of cadmium as well as for tellurium and tin isotopes show a pronounced shell effect towards and at N=82. Shell quenching cannot be deduced from a single new mass value, nor by a better agreement with a theoretical model which explicitly takes into account a quenching feature. This is in agreement with the conclusion from \u3b3-ray spectroscopy and confirms modern shell-model calculations

Model-independent evidence for J/ψpJ/\psi p contributions to Λb0→J/ψpK−\Lambda_b^0\to J/\psi p K^- decays

The data sample of $\Lambda_b^0\to J/\psi p K^-$ decays acquired with the LHCb detector from 7 and 8~TeV $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$, is inspected for the presence of $J/\psi p$ or $J/\psi K^-$ contributions with minimal assumptions about $K^- p$ contributions. It is demonstrated at more than 9 standard deviations that $\Lambda_b^0\to J/\psi p K^-$ decays cannot be described with $K^- p$ contributions alone, and that $J/\psi p$ contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for $P_c^+\to J/\psi p$ charmonium-pentaquark states in the same data sample.Comment: 21 pages, 12 figures (including the supplemental section added at the end

Observation of Z production in proton-lead collisions at LHCb

The first observation of Z boson production in proton-lead collisions at a centre-of-mass energy per proton-nucleon pair of root(s) N N = 5TeV is presented. The data sample corresponds to an integrated luminosity of 1.6 nb(-1) collected with the LHCb detector. The Z candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above 20 GeV/c. The invariant dimuon mass is restricted to the range 60-120 GeV/c. The Z production cross-section is measured to be sigma(Z ->mu+mu-) (fwd) = 13.5(-4.0)(+5.4)(stat.) +/- 1.2(syst.) nb in the direction of the proton beam and sigma(Z ->mu+mu-) (bwd) = 10.7(-5.1)(+8.4)(stat.) +/- 1.0(syst.) nb in the direction of the lead beam, where the first uncertainty is statistical and the second systematic

Measurement of Upsilon production in pp collisions at \sqrt{s} = 7 TeV

The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons in proton-proton collisions at the centre-of-mass energy of sqrt(s)=7 TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb-1 collected at the Large Hadron Collider. The Upsilon mesons are reconstructed in the decay mode Upsilon -> mu+ mu- and the signal yields are extracted from a fit to the mu+ mu- invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the Upsilon transverse momentum pT and rapidity y, over the range pT < 15 GeV/c and 2.0 < y < 4.5. The cross-sections times branching fractions, integrated over these kinematic ranges, are measured to be sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S)->mu+ mu-) = 2.29 {\pm} 0.01 {\pm} 0.10 -0.37 +0.19 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S)->mu+ mu-) = 0.562 {\pm} 0.007 {\pm} 0.023 -0.092 +0.048 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S)->mu+ mu-) = 0.283 {\pm} 0.005 {\pm} 0.012 -0.048 +0.025 nb, where the first uncertainty is statistical, the second systematic and the third is due to the unknown polarisation of the three Upsilon states.Comment: 22 pages, 7 figure

Measurement of the Bs0→J/ψK∗0B^0_s\rightarrow J/\psi K^{*0} branching fraction and angular amplitudes

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 $f_{||} = 0.19^{+0.10}_{-0.08} \pm 0.02$

Evidence for CP violation in time-integrated D0 -> h-h+ decay rates

A search for time-integrated CP violation in D0 -> h-h+ (h=K, pi) decays is presented using 0.62 fb^-1 of data collected by LHCb in 2011. The flavor of the charm meson is determined by the charge of the slow pion in the D*+ -> D0 pi+ and D*- -> D0bar pi- decay chains. The difference in CP asymmetry between D0 -> K-K+ and D0 -> pi-pi+, Delta ACP = ACP(K-K+) - ACP(pi-pi+), is measured to be [-0.82 \pm 0.21(stat.) \pm 0.11(syst.)]%. This differs from the hypothesis of CP conservation by 3.5 standard deviations.Comment: 8 pages, 3 figures, 2 tables; v2 minor updates after journal revie

Mass and Lifetime Measurements in Storage Rings

Masses of nuclides covering a large area of the chart of nuclides can be measured in storage rings where many ions circulate at the same time. In this paper the recent progress in the analysis of Schottky mass spectrometry data is presented as well as the technical improvements leading to higher accuracy for isochronous mass measurements with a time\u2010of\u2010flight detector. The high sensitivity of the Schottky method down to single ions allows to measure lifetimes of nuclides by observing mother and daughter nucleus simultaneously. In this way we investigated the decay of bare and H\u2010like 140Pr. As we could show the lifetime can be even shortened compared to those of atomic nuclei despite of a lower number of electrons available for internal conversion or electron capture. All these techniques will be implemented with further improvements at the storage rings of the new FAIR facility at GSI in the future

Half-life measurement of stored fully ionized and hydrogen-like 122I ions

The half-lives of fully ionized and hydrogen-like (H-like) 122I ions have been measured in a heavy-ion storage ring. The \u3b2+-decay constants for both charge states and the electron capture (EC) decay constant of H-like ions have been determined. The EC-decay constant in H-like 122I ions \u3bbH-like EC = 7.35(33) \ub7 10 124 s 121 is, within the uncertainty, the same as the one in neutral atoms. This result is in agreement with the estimates of recent theoretical considerations on the EC-decay of few-electron ions that explicitly take into account the conservation of the total angular momentum of the nucleus plus lepton(s) system and its projections. No firm confirmation could be concluded from our results on the predicted effect that allowed Gamow-Teller transitions become forbidden if the initial and final total angular momenta are not equal

New Developments for Isochronous Mass Measurements of Short-Lived Nuclei

The combination of the in\u2010flight separator FRS and the storage\u2010ring ESR at GSI offers unique possibilities for high accuracy mass and lifetime measurements of bare and few\u2010electron fragments. Operating the ESR in the isochronous mode allows for measurements of revolution frequencies of stored ions without cooling. Isochronous Mass Spectrometry (IMS) can be applied to fragments with half\u2010lives as short as several tens of microseconds. Newly developed magnetic rigidity tagging increases the resolving power of IMS to about 500000. IMS can be used to measure masses of nuclei with rates even lower than one ion per day, a property also needed for the purpose of the ILIMA project at the future facility FAIR