CERN Accelerating science

LHCb Note
Report number	LHCb-CONF-2011-035 ; CERN-LHCb-CONF-2011-035
Title	Analysis of $\bar{B}^0_s\to J/\psi \left(\pi^+\pi^-~{\rm and~}K^+K^-\right)$ and the first observation of $J/\psi f'_2(1525)$
Corporate author(s)	The LHCb Collaboration
Collaboration	LHCb Collaboration
Note	LHCb-ANA-2011-049
Submitted to	2011 Europhysics Conference on High Energy Physics, Grenoble, France, 21 - 27 Jul 2011
Submitted by	[email protected] on 08 Jul 2011
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; LHCb
Free keywords	flavour physics ; B physics ; CP violation
Abstract	Measurement of mixing induced CP violation in $\bar{B}^0_s$ decays is of prime importance in probing new physics. So far only the channel $\bar{B}^0_s \to J/\psi\phi$ has been used. Here we investigate $\bar{B}^0_s $ decays into CP eigenstates and other modes in the $J/\psi \pi^+\pi^-$ and $J/\psi K^+ K^-$ final states. The $\pi^+\pi^-$mass spectrum has a relatively narrow structure peaking near 980 MeV first found by LHCb, that we identify as the $f_0(980)$, and show that it is consistent with being pure S-wave. Thus, this is a CP-odd eigenstate. The ratio of rates for $J/\psi f_0(980)$ to $J/\psi \phi$, with $f_0(980)\to\pi^+\pi^-$ in a $\pm$90 MeV mass window around the $f_0(980)$ and $\phi\to K^+K^-$ is $R^{f_0}_{\rm effective}=(21.7\pm1.1\pm$0.7)%. Other structures at higher mass are shown to contain D-wave. The $K^+K^-$ spectrum besides a large $\phi$ component has significant $f'_2(1525)$. The ratio of rates for $J/\psi f'_2(1525)$ to $J/\psi \phi$, with $f'_2(1525)\to K^+K^-$ in a $\pm$125 MeV mass window around the $f'_2(1525)$ is $R^{f'_2}_{\rm effective}=(19.4\pm1.8\pm1.1$)%. These new channels may be useful for different aspects of CP violation measurements.
Copyright/License	Preprint: (License: CC-BY-4.0)
Related document	Superseded by LHCB-PAPER-2011-026

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