AbstractA structure is observed in the $${B} ^{\pm }{K} ^{\mp }$$
B
±
K
∓
mass spectrum in a sample of proton–proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9$$\,\text {fb} ^{-1}$$
fb
-
1
. The structure is interpreted as the result of overlapping excited $${B} ^0_{s} $$
B
s
0
states. With high significance, a two-peak hypothesis provides a better description of the data than a single resonance. Under this hypothesis the masses and widths of the two states, assuming they decay directly to $${B} ^{\pm }{K} ^{\mp }$$
B
±
K
∓
, are determined to be $$\begin{aligned} m_1&= 6063.5 \pm 1.2 \text { (stat)} \pm 0.8\text { (syst)}\,\text {Me}\text {V}, \\ \Gamma _1&= 26 \pm 4 \text { (stat)} \pm 4\text { (syst)}\,\text {Me}\text {V}, \\ m_2&= 6114 \pm 3 \text { (stat)} \pm 5\text { (syst)}\,\text {Me}\text {V}, \\ \Gamma _2&= 66 \pm 18 \text { (stat)} \pm 21\text { (syst)}\,\text {Me}\text {V}. \end{aligned}$$
m
1
=
6063.5
±
1.2
(stat)
±
0.8
(syst)
Me
,
Γ
1
=
26
±
4
(stat)
±
4
(syst)
Me
,
m
2
=
6114
±
3
(stat)
±
5
(syst)
Me
,
Γ
2
=
66
±
18
(stat)
±
21
(syst)
Me
.
Alternative values assuming a decay through $${B} ^{*\pm }{K} ^{\mp }$$
B
∗
±
K
∓
, with a missing photon from the $$B^{*\pm } \rightarrow B^{\pm }\gamma $$
B
∗
±
→
B
±
γ
decay, which are shifted by approximately 45$$\,\text {Me}$$
Me
V, are also determined. The possibility of a single state decaying in both channels is also considered. The ratio of the total production cross-section times branching fraction of the new states relative to the previously observed $$B_{s2}^{*0}$$
B
s
2
∗
0
state is determined to be $$0.87 \pm 0.15 \text { (stat)} \pm 0.19 \text { (syst)}$$
0.87
±
0.15
(stat)
±
0.19
(syst)
.
Search for new neutral gauge bosons with the CMS Experiment at the LHC
