Abstract
Invariant mass distributions of B+pi- and B0pi+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb-1 of pp collision data, recorded by the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B_1(5721)^(0,+) and B_2*(5747)^(0,+) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 5850--6000 MeV in both B+pi- and B0pi+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B_J(5840)^(0,+) and B_J(5960)^(0,+), whose masses and widths are obtained under different hypotheses for their quantum numbers.
Highlights
Detector and datasetThe LHCb detector [23, 24] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks
A wide range of values, as shown in figure 1 [3,4,5,6,7,8,9,10]
While in the D meson system amplitude analyses of excited states produced in B decays can be used to determine their spin and parity, in the B meson system it is very difficult to assign with certainty quantum numbers to observed states
Summary
The LHCb detector [23, 24] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks. The detector includes a high-precision tracking system consisting of a silicon-strip vertex detector [25] surrounding the pp interaction region, a large-area silicon-strip detector located upstream of a dipole magnet with a bending power of about 4 Tm, and three stations of silicon-strip detectors and straw drift tubes [26] placed downstream of the magnet. The trigger [29] consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which uses information from the vertex detector and tracking system. Decays of hadronic particles are described by EvtGen [32], in which final-state radiation is generated using Photos [33]. The interaction of the generated particles with the detector, and its response, are implemented using the Geant toolkit [34, 35] as described in ref. The interaction of the generated particles with the detector, and its response, are implemented using the Geant toolkit [34, 35] as described in ref. [36]
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