CMS-BPH-13-009

CMS-BPH-13-009 ; CERN-EP-2016-161
Observation of the decay $\mathrm{B}^+ \to \psi( 2 \mathrm{S} ) \phi(1020) \mathrm{ K }^+$ in pp collisions at $\sqrt{s} = $ 8 TeV
CMS Collaboration
10 July 2016
Phys. Lett. B 764 (2017) 66
Abstract: The decay $\mathrm{B}^+ \to \psi( 2 \mathrm{S} ) \phi(1020) \mathrm{ K }^+$ is observed for the first time using data collected from pp collisions at $\sqrt{s} = $ 8 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.6 fb$^{-1}$. The branching fraction of this decay is measured, using the mode $\mathrm{B}^+\to \psi( 2 \mathrm{S} ) \mathrm{ K }^+$ as normalization, to be ( 4.0 $\pm$ 0.4 (stat) $\pm$ 0.6 (syst) $\pm$ 0.2 ($\mathcal{B})$ )$\times$ 10$^{-6}$, where the third uncertainty is from the imprecision in the normalization channel.
Links: e-print arXiv:1607.02638 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: The $\psi( 2 \mathrm{S} ) \phi \mathrm{ K }^+ $ mass distribution after the selection requirements. The solid curve shows the result of fitting this distribution to a signal represented by two Gaussian functions and a first-order polynomial for the background. The shaded area represents the signal component, while the dotted line shows the fitted background contribution.
png pdf	Figure 2: The distributions of the $\mathrm{ K }^+ \mathrm{ K }^- $ invariant mass closest to the nominal $\phi $ mass within (a) and outside (b) the $\mathrm{B}^+ $ mass window. The results show the total fit, as well as the four components: $\phi $ signal, non-$\mathrm{B}^+ $ background, non-$\phi $ signal, and in (b) the Crystal Ball function component of the non-$\mathrm{B}^+ $ background.
png pdf	Figure 2-a: The distributions of the $\mathrm{ K }^+ \mathrm{ K }^- $ invariant mass closest to the nominal $\phi $ mass within (a) and outside (b) the $\mathrm{B}^+ $ mass window. The results show the total fit, as well as the four components: $\phi $ signal, non-$\mathrm{B}^+ $ background, non-$\phi $ signal, and in (b) the Crystal Ball function component of the non-$\mathrm{B}^+ $ background.
png pdf	Figure 2-b: The distributions of the $\mathrm{ K }^+ \mathrm{ K }^- $ invariant mass closest to the nominal $\phi $ mass within (a) and outside (b) the $\mathrm{B}^+ $ mass window. The results show the total fit, as well as the four components: $\phi $ signal, non-$\mathrm{B}^+ $ background, non-$\phi $ signal, and in (b) the Crystal Ball function component of the non-$\mathrm{B}^+ $ background.
png pdf	Figure 3: The $\psi( 2 \mathrm{S} ) \mathrm{ K }^+ $ invariant mass distribution after implementing all the event selection requirements. The solid curve shows the result of fitting this distribution to a signal corresponding to two Gaussian functions and a first-order polynomial for the background. The shaded area represents the contribution from the $\mathrm{B}^+ \to \psi( 2 \mathrm{S} )\mathrm{ K }^+ $ channel, while the dotted line shows the fitted background contribution.
png pdf	Figure 4: The $\psi( 2 \mathrm{S} ) \mathrm{ K }^+ \mathrm{ K }^- \mathrm{ K }^+ $ invariant mass distribution with no $\phi $ mass selection. The solid curve shows the result of fitting this distribution to a signal represented by two Gaussian functions and a second-order polynomial for the background. The shaded area represents the signal component, while the dotted line shows the fitted background contribution.

Tables
png pdf	Table 1: The selection criteria derived from the optimization procedure.
png pdf	Table 2: Relative systematic uncertainties in the measurement of $\mathcal {B}(\mathrm{B}^+ \to \psi( 2 \mathrm{S} ) \phi \mathrm{ K }^+ )$ in percent. The total systematic uncertainty corresponds to the sum in quadrature of the listed uncertainties.

Summary

In summary, the $\mathrm{B}^+\to \psi( 2 \mathrm{S} )\phi \mathrm{ K }^+$ decay has been observed for the first time by the CMS Collaboration. The result has been achieved using data from pp collisions at $\sqrt{s} =$ 8 TeV, corresponding to an integrated luminosity of 19.6 fb$^{-1}$. The branching fraction $\mathcal{B}(\mathrm{B}^+\to \psi( 2 \mathrm{S} )\phi\mathrm{ K }^+)$ is determined to be (4.0 $\pm$ 0.4 (stat) $\pm$ 0.6 (syst) $\pm$ 0.2 ($\mathcal{B}$))$\times$ 10$^{-6}$, where the third uncertainty reflects the imprecision in the value of $\mathcal{B}(\mathrm{B}^+\to \psi( 2 \mathrm{S} )\mathrm{ K }^+)$. The upper limit on the fraction of $\mathrm{B}^+\to \psi( 2 \mathrm{S} ) (\text{non-}\phi)\mathrm{ K }^+$ decays in $\mathrm{B}^+ \to \psi( 2 \mathrm{S} ) \mathrm{ K }^+\mathrm{ K }^+\mathrm{ K }^+$ channel is found to be 0.26 at 95% confidence. The observation of $\mathrm{B}^+\to \psi( 2 \mathrm{S} )\phi \mathrm{ K }^+$ offers future opportunities in searches for resonances in the $\psi( 2 \mathrm{S} )\phi$ mass spectrum.

References
1	CDF Collaboration	Evidence for a Narrow Near-Threshold Structure in the $ \mathrm{J}/\psi\phi $ Mass Spectrum in $ B^+\to \mathrm{J}/\psi\phi K^+ $ Decays	PRL 102 (2009) 242002	0903.2229
2	LHCb Collaboration	Search for the $ X(4140) $ state in $ B^+ \to \mathrm{J}/\psi \phi K^+ $ decays	PRD 85 (2012) 091103	1202.5087
3	D0 Collaboration	Search for the X(4140) state in $ B^{+}\rightarrow \mathrm{J}/\psi \phi K^+ $ decays with the D0 detector	PRD 89 (2014) 012004	1309.6580
4	CMS Collaboration	Observation of a peaking structure in the $ \mathrm{J}/\psi \phi $ mass spectrum from $ B^{\pm} \to \mathrm{J}/\psi \phi K^{\pm} $ decays	PLB 734 (2014) 261	CMS-BPH-11-026 1309.6920
5	BaBar Collaboration	Study of $ B^{\pm,0} \to \mathrm{J}/\psi K^+ K^- K^{\pm,0} $ and search for $ B^0 \to \mathrm{J}/\psi\phi $ at BaBar	PRD 91 (2015) 012003	1407.7244
6	LHCb Collaboration	Observation of $ \mathrm{J}/\psi\phi $ structures consistent with exotic states from amplitude analysis of $ B^+\to\mathrm{J}/\psi \phi K^+ $ decays		1606.07895
7	LHCb Collaboration	Amplitude analysis of $ B^+\to \mathrm{J}/\psi \phi K^+ $ decays		1606.07898
8	CMS Collaboration	Description and performance of track and primary-vertex reconstruction with the CMS tracker	JINST 9 (2014) P10009	CMS-TRK-11-001 1405.6569
9	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
10	T. Sjostrand, S. Mrenna, and P. Skands	PYTHIA 6.4 physics and manual	JHEP 05 (2006) 026	hep-ph/0603175
11	D. J. Lange	The EvtGen particle decay simulation package	NIMA 462 (2001) 152
12	GEANT4 Collaboration	GEANT4: A simulation toolkit	NIMA 506 (2003) 250
13	Particle Data Group, K. A. Olive et al.	Review of Particle Physics	CPC 38 (2014) 090001
14	CMS Collaboration	CMS tracking performance results from early LHC operation	EPJC 70 (2010) 1165	CMS-TRK-10-001 1007.1988
15	G. Punzi	Sensitivity of searches for new signals and its optimization	in Proceedings of PHYSTAT 2003, Statistical problems in particle physics, astrophysics and cosmology, L. Lyons, R. P. Mount, and R. Reitmeyer, eds Stanford, USA	physics/0308063
16	W. Verkerke and D. P. Kirkby	The RooFit toolkit for data modeling	in Proceedings of PHYSTAT 05: Statistical problems in particle physics, astrophysics and cosmology, L. Lyons and M. Karagoz, eds Oxford, 2005	physics/0306116
17	S. M.Flatt\'e et al.	Analysis of the observed anomaly in $ \pi\pi $ s-wave scattering near $ \mathrm{K \bar{K}} $ threshold	PLB 38 (1972) 232
18	M. J. Oreglia	A study of the reactions $\psi' \to \gamma\gamma \psi$	PhD thesis, Stanford University, 1980 SLAC Report SLAC-R-236, see Appendix D
19	T. Junk	Confidence level computation for combining searches with small statistics	NIMA 434 (1999) 435	hep-ex/9902006
20	A. L. Read	Presentation of search results: the $ \it{CL}_{s} $ technique	JPG 28 (2002) 2693
21	G. Cowan, K. Cranmer, E. Gross, and O. Vitells	Asymptotic formulae for likelihood-based tests of new physics	EPJC 71 (2011) 1554	1007.1727