Precision measurement of the Ξcc++Ξcc++ {\varXi}_{cc}^{++} mass

A measurement of the Ξ++cc mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb−1. The Ξ++cc candidates are reconstructed via the decay modes Ξ++cc→Λ+cK−π+π+ and Ξ++cc→Ξ+cπ+. The result, 3621.55 ± 0.23 (stat) ± 0.30 (syst) MeV/c2, is the most precise measurement of the Ξ++cc mass to date

Amplitude analysis of the B+→π+π+π− decay

The results of an amplitude analysis of the charmless three-body decay B + → π + π + π − , in which C P -violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of 3     fb − 1 of p p collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description of the behavior of the π + π −     S -wave contribution, which is achieved by using three complementary approaches based on the isobar model, the K -matrix formalism, and a quasi-model-independent procedure. Additional resonant contributions for all three methods are described using a common isobar model, and include the ρ ( 770 ) 0 , ω ( 782 ) and ρ ( 1450 ) 0 resonances in the π + π − P -wave, the f 2 ( 1270 ) resonance in the π + π − D -wave, and the ρ 3 ( 1690 ) 0 resonance in the π + π − F -wave. Significant C P -violation effects are observed in both S - and D -waves, as well as in the interference between the S - and P -waves. The results from all three approaches agree and provide new insight into the dynamics and the origin of C P -violation effects in B + → π + π + π − decays

Measurement of psi (2S) production cross-sections in proton-proton collisions at v s=7 and 13 TeV

The cross-sections of \u3c8(2 S) meson production in proton-proton collisions at s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275pb-1. The production cross-sections for prompt \u3c8(2 S) mesons and those for \u3c8(2 S) mesons from b-hadron decays (\u3c8(2S)-from-b) are determined as functions of the transverse momentum, pT, and the rapidity, y, of the \u3c8(2 S) meson in the kinematic range 2<20GeV/c and 2.0 < y< 4.5. The production cross-sections integrated over this kinematic region are \u3c3(prompt\u3c8(2S),13TeV)=1.430\ub10.005(stat)\ub10.099(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,13TeV)=0.426\ub10.002(stat)\ub10.030(syst)\u3bcb.A new measurement of \u3c8(2 S) production cross-sections in pp collisions at s=7TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614pb-1. The integrated production cross-sections in the kinematic range 3.5<14GeV/c and 2.0 < y< 4.5 are \u3c3(prompt\u3c8(2S),7TeV)=0.471\ub10.001(stat)\ub10.025(syst)\u3bcb,\u3c3(\u3c8(2S)-from-b,7TeV)=0.126\ub10.001(stat)\ub10.008(syst)\u3bcb.All results show reasonable agreement with theoretical calculations

Erratum to: Measurement of ψ(2 S) meson production in pp collisions at s = 7 TeV (The European Physical Journal C, (2012), 72, 8, (2100), 10.1140/epjc/s10052-012-2100-4)

This erratum corrects measurements of the prompt and secondary (from-b).</jats:p

Erratum to: Study of ϒ production in p Pb collisions at s NN = 8. 16 TeV

In figure 11 of the original paper

Measurement of psi (2S) production cross-sections in proton-proton collisions at v s=7 and 13 TeV

The cross-sections of.(2S) meson production in proton-proton collisions at v s = 13 TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275 pb-1. The production cross-sections for prompt.(2S) mesons and those for.(2S) mesons from b-hadron decays (.(2S)-from-b) are determined as functions of the transverse momentum, pT, and the rapidity, y, of the.(2S) meson in the kinematic range 2 < pT < 20 GeV/c and 2.0 < y < 4.5. The production cross-sections integrated over this kinematic region are s(prompt.(2S), 13 TeV) = 1.430 +/- 0.005 (stat) +/- 0.099 (syst) mu b, s(.(2S)-from-b, 13 TeV) = 0.426 +/- 0.002 (stat) +/- 0.030 (syst) mu b. A new measurement of.(2S) production cross-sections in pp collisions at v s = 7 TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614 pb-1. The integrated production cross-sections in the kinematic range 3.5 < pT < 14 GeV/c and 2.0 < y < 4.5 are s(prompt.(2S), 7 TeV) = 0.471 +/- 0.001 (stat) +/- 0.025 (syst) mu b, s(.(2S)-from-b, 7 TeV) = 0.126 +/- 0.001 (stat) +/- 0.008 (syst) mu b. All results show reasonable agreement with theoretical calculations

Measurement of ψ ( 2 S ) production cross-sections in proton-proton collisions at s = 7 and 13 TeV

Abstract: The cross-sections of ψ(2S) meson production in proton-proton collisions at s=13TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275pb-1. The production cross-sections for prompt ψ(2S) mesons and those for ψ(2S) mesons from b-hadron decays (ψ(2S)-from-b) are determined as functions of the transverse momentum, pT, and the rapidity, y, of the ψ(2S) meson in the kinematic range 2<pT<20GeV/c and 2.0<y<4.5. The production cross-sections integrated over this kinematic region are σ(promptψ(2S), 13TeV)=1.430±0.005(stat)±0.099(syst)μb, σ(ψ(2S)-from-b, 13TeV)=0.426±0.002(stat)±0.030(syst)μb.A new measurement of ψ(2S) production cross-sections in pp collisions at s=7TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614pb-1. The integrated production cross-sections in the kinematic range 3.5<pT<14GeV/c and 2.0<y<4.5 are σ(promptψ(2S), 7TeV)=0.471±0.001(stat)±0.025(syst)μb, σ(ψ(2S)-from-b, 7TeV)=0.126±0.001(stat)±0.008(syst)μb.All results show reasonable agreement with theoretical calculations

Precision measurement of the Ξ cc + + mass

Abstract: A measurement of the Ξcc++ mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb−1. The Ξcc++ candidates are reconstructed via the decay modes Ξcc++→Λc+K−π+π+ and Ξcc++→Ξc+π+. The result, 3621.55 ± 0.23 (stat) ± 0.30 (syst) MeV/c2, is the most precise measurement of the Ξcc++ mass to date

Search for the doubly charmed baryon Ξ cc + in the Ξ c + π − π + final state

Abstract: A search for the doubly charmed baryon Ξcc+ is performed in the Ξc+π−π+ invariant-mass spectrum, where the Ξc+ baryon is reconstructed in the pK−π+ final state. The study uses proton-proton collision data collected with the LHCb detector at a centre- of-mass energy of 13 TeV, corresponding to a total integrated luminosity of 5.4 fb−1. No significant signal is observed in the invariant-mass range of 3.4–3.8 GeV/c2. Upper limits are set on the ratio of branching fractions multiplied by the production cross-section with respect to the Ξcc++→ (Ξc+→ pK−π+)π+ decay for different Ξcc+ mass and lifetime hypotheses in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2.5 to 25 GeV/c. The results from this search are combined with a previously published search for the Ξcc+→Λc+K−π+ decay mode, yielding a maximum local significance of 4.0 standard deviations around the mass of 3620 MeV/c2, including systematic uncertainties. Taking into account the look-elsewhere effect in the 3.5–3.7 GeV/c2 mass window, the combined global significance is 2.9 standard deviations including systematic uncertainties

Development of a new experimental method for studies of muon capture in hydrogen

A new experiment is under preparation with the aim to improve considerably the present knowledge of the rate Lambda(s), which should be measured on a level of 1% or better, for the basic electroweak capture reaction of a negative muon on the free proton mup(1s) --> n + nu(mu). The capture rate will be determined by measuring the lifetime of mu(-) stopped in ultra pure hydrogen at 10 bar pressure and comparing it with the lifetime of the unbound mu(+). A new experimental method was developed for this project which should allow measuring the mu(-) lifetime with at least 10 ppm precision. The basic element of the detector is operating in the hydrogen gas time projection chamber (TPC) surrounded by multi-wire proportional chambers (MWPCs) and scintillator counters. The arrival times and trajectories of the incoming muons and the outgoing decay electrons are measured with this device providing effective suppression of background. Using the TPC as an active target, we can monitor on-line the protium contamination by impurities with a sensitivity better than 10(-8). This can be done by detecting the charged products of the muon capture reaction on these impurities. It was demonstrated that the TPC and MWPCs can operate in pure hydrogen under 10 bar pressure providing gas gain up to 10 000