Results are reported from an amplitude analysis of the B+ → D+D− K+ decay. The analysis is carried out using LHCb proton-proton collision data taken at √s = 7, 8, and 13 TeV, corresponding to a total ...integrated luminosity of 9 fb−1. In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the D−K+ channel with masses around 2.9 GeV/c2, and a new spin-0 charmonium resonance in proximity to the spin-2 χc2(3930) state.
Display omitted
Using proton-proton collision data at centre-of-mass energies of s=7,8 and 13TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated ...luminosity of 9fb-1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4GeV/c2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit-Wigner lineshape.
The branching fraction of the rare decay Λ b0 → Λ ( 1520 ) μ+μ- is measured for the first time, in the squared dimuon mass intervals q2 , excluding the J/ψ and ψ ( 2S ) regions. The data sample ...analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb-1 . The result in the highest q2 interval, q2>15.0 GeV2/c4 , where theoretical predictions have the smallest model dependence, agrees with the predictions.
The production of χ_{c1}(3872) and ψ(2S) hadrons is studied as a function of charged particle multiplicity in pp collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated ...luminosity of 2 fb^{-1}. For both states, the fraction that is produced promptly at the collision vertex is found to decrease as charged particle multiplicity increases. The ratio of χ_{c1}(3872) to ψ(2S) cross sections for promptly produced particles is also found to decrease with multiplicity, while no significant dependence on multiplicity is observed for the equivalent ratio of particles produced away from the collision vertex in b-hadron decays. This behavior is consistent with a calculation that models the χ_{c1}(3872) structure as a compact tetraquark. Comparisons with model calculations and implications for the binding energy of the χ_{c1}(3872) state are discussed.
The relative branching fractions of B+ → h+h'+h'− decays, where h(') is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to ...an integrated luminosity of 3.0 fb−1 of pp collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless hadronic decays of B+ mesons.
The mass difference between the Omega -b and Xi -b baryons is measured using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1, and is ...found to be mo Omega -bthorn - mo Xi -bthorn 1/4 248.54? 0.51ostatthorn ? 0.38osystthorn MeV=c2. The mass of the Omega -b baryon is measured to be mo Omega -bthorn 1/4 6045.9 ? 0.5ostatthorn ? 0.6osystthorn MeV=c2. This is the most precise determination of the Omega -b mass to date. In addition, the production rate of Omega -b baryons relative to that of Xi -b baryons is measured for the first time in pp collisions, using an LHCb dataset collected at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 6 fb-1. Reconstructing beauty baryons in the kinematic region 2 < <eta> < 6 and pT < 20 GeV=c with their decays to a J=psi meson and a hyperon, the ratio f Omega- b f Xi- b tation fractions of b quarks into Omega -b and Xi -b baryons, respectively, and B represents the branching fractions of their respective decays.
Search for the radiative Ξb− → Ξ−γ decay Ackernley, T.; Alexander, M.; Anderlini, L. ...
The journal of high energy physics,
01/2022, Letnik:
2022, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A
bstract
The first search for the rare radiative decay
Ξ
b
−
→ Ξ
−
γ
is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, ...corresponding to an integrated luminosity of 5.4 fb
−
1
. The
Ξ
b
−
→ Ξ
−
J/ψ
channel is used as normalization. No
Ξ
b
−
→ Ξ
−
γ
signal is found and an upper limit of
B
(
Ξ
b
−
→ Ξ
−
γ
)
<
1
.
3 × 10
−
4
at 95% confidence level is obtained.
PDF
