Mass and Width Measurement of Orbitally Excited (L=1) B**0 Mesons

Mass and Width Measurement of Orbitally Excited (L=1) B^**0 Mesons

Primary authors: Andreas Gessler, Jen Pursley, Petar Maksimovic, Thomas Kuhr, Michal Kreps, Michael Feindt

This webpage summarizes the blessed results for the observation of the orbitally excited (L = 1) B^**0 mesons in the fully reconstructed decay B^**0 → B⁺ π^- or in the decay B^**0 → B^+* π^- (B^+* → B⁺ γ), where we do not detect the γ.

The B⁺ mesons are fully reconstructed in three decay channels:
B⁺ → J/ψ K⁺ (J/ψ → μ⁺ μ^- ),
B⁺ → D⁰ π⁺ (D⁰ → K⁺ π^- ), and
B⁺ → D⁰ 3π⁺ (D⁰ → K⁺ π^- ).

The results have been produced for the summer conferences 2007 and were blessed in the B Physcis Meeting on Thursday July 26, 2007. Updates to these results were blessed in the B Physcis Meeting on Thursday July 3, 2008.

We measure Q values ( m(B⁺ π^-) - m(B⁺) - m(π^-) ) of:

Q(B₂^*0) = 321.5^+1.7_-1.8 (stat.) ^+0.9_-0.7 (syst.) MeV/c²
m(B₂^*0) - m(B₁⁰) = 14.9^+2.2_-2.5 (stat.) ^+1.2_-1.4 (syst.) MeV/c²
And Γ(B₂^*0)
Γ(B₂^*0) = 22.7^+3.8_-3.2 (stat.) ^+3.2_-10.2 (syst.) MeV/c²

The resulting mass measurements of this analysis are:

m(B₁⁰) = 5725.3^+1.6_-2.2 (stat.) ^+1.4_-1.5 (syst.) MeV/c²
m(B₂^*0) = 5740.2^+1.7_-1.8 (stat.) ^+0.9_-0.8 (syst.) MeV/c²

A more detailed summary of the results can be found in this public note.

Below are all blessed figures for downloads.

Figure 1 ( gif ): Transition diagram of B^** states
Figure 2a ( gif ): Invariant mass distribution of B⁺ candidates m(K ⁺ J/ψ)
Figure 2b ( gif ): Invariant mass distribution of B⁺ candidates m(D π ⁺)
Figure 2c ( gif ): Invariant mass distribution of B⁺ candidates m(D 3π ⁺)

Bellow are plots with some more details showing data in separate B⁺ channels, with and without fit and NN output distribution to demonstrate separation between signal and background.

Figure 3a ( gif ): The distribution of the Neural Network output for background(data) and signal(MC simulation) trained for B^**0 for the decay channel including B⁺ → J/ψ K⁺
Figure 3b ( gif ): The distribution of the Neural Network output for background(data) and signal(MC simulation) trained for B^**0 for the decay channel including B⁺ → D π⁺
Figure 3c ( gif ): The distribution of the Neural Network output for background(data) and signal(MC simulation) trained for B^**0 for the decay channel including B⁺ → D 3π⁺
Plots with cut optimized on single channel
Figure 4a ( gif ): Q value distribution of the B^**0 candidates with B⁺ → J/ψ K⁺ decay
Figure 4b ( gif ): Q value distribution of the B^**0 candidates with B⁺ → D π⁺ decay
Figure 4c ( gif ): Q value distribution of the B^**0 candidates with B⁺ → D 3π⁺ decay
Figure 4d ( gif ): Q value distribution of the B^**0 candidates with all three B⁺ decays summed together
Plots with cuts optimized in 3D scan over channels
Figure 5a ( gif ): Q value distribution of the B^**0 candidates with B⁺ → J/ψ K⁺ decay
Figure 5b ( gif ): Q value distribution of the B^**0 candidates with B⁺ → D π⁺ decay
Figure 5c ( gif ): Q value distribution of the B^**0 candidates with B⁺ → D 3π⁺ decay
Figure 5d ( gif ): Q value distribution of the B^**0 candidates with all three B⁺ decays summed together
Fits to individual channels, optimized on a single channel
Figure 6a ( gif ): Fit to Q value distribution of the B^**0 candidates with B⁺ → J/ψ K⁺ decay
Figure 6b ( gif ): Fit to Q value distribution of the B^**0 candidates with B⁺ → D π⁺ decay
Figure 6c ( gif ): Fit to Q value distribution of the B^**0 candidates with B⁺ → D 3π⁺ decay
Final fit to combined channels
Figure 7 ( gif ): Fit to the Q value distribution of the B^**0 candidates with all three B⁺ decays summed together using 3D scan over channels for optimal selection