B Lifetimes and X,Y,Z States at the Tevatron Page: 4 of 5
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CDF Run II Preliminary 4.3 fb CDF Run II Preliminary 4.3 fb CDF Run II Preliminary 4.3 fb
E 10 DtEDaaED a
(a) Sigal , (b) Signal (c) SignIl
Signal+Bkg Signal+Bkg Signal+Bkg
Figure 1: Decay time distributions for (a) B+ -> J/ jK+, (b) B0 -> J/ jK*, and (c) A -> J/yA0 candidates.
tions. For the Awe measure r(A ) = [1 .537 +(stat)0.045 +(syst)0.01 4] ps and RA = [1 .020 +
0.030(stat) 0.008(syst)]. This measurement is the most precise measurement of z(A ) and is con-
sistent with the previous CDF measurement in this decay channel of z(A ) = [1. 593 8 (stat)
0.033(syst)] ps [6] but is more than 2u larger than the world average of 1. 383188j ps and the previ-
ous CDF measurement [7], performed on a different decay channel (A-7wT): [1.401 t 0.046(stat)
0.035(syst)] ps . The ratio is also higher than the predicted value of 0.88 0.05 [5] but in agreement
with 1.063 0.027 [8]. These measurements are complemented by the world-leading ZBO measure-
ment from the angular analysis of Bi -> J/ip' decays [9]: [1.530 0.025(stat) 0.012(syst)] PS.
2. X,Y,Z states:
CDF is playing a significant role in the study of exotic X,Y and Z states with the first confir-
mation of X(3872) [10], the measurements of its quantum numbers[11], the precision mass mea-
surement of X(3872) [12] and the Y(4140) evidence [13].
An update [14] on the search for structures in the J/[153 system produced in exclusive B
J/ijtpK+ decays with J/f -> p0 y- and -> K+K is reported here. This analysis is based
on an integrated luminosity of about 6.0 fb . The same requirements applied in [13] are used.
The major points of the analysis are the use of L to separate B vertex from the primary vertex
and the use of kaon particle identification to reduce combinatorial background. Fig. 2 shows the
invariant mass of J/atK+ after the requirements of [13]. A fit with a Gaussian signal function
and a linear background function to the mass spectrum returns a B+ signal of 115 12 events.
We increased the B+ -> J/na K+ statistics by 53 % comparing to previous analysis [13]. The
same model described in reference [13] is used as well, in order to examine the Y(4140) structure.
The enhancement is modelled by an S-wave relativistic Breit-Wigner function [15] convoluted
with a Gaussian resolution function with the r.m.s. fixed to 1.7 MeV/c2 obtained from MC, and a
three-body phase space [4] is used to describe the background shape. An unbinned fit to the AM =
m(p - K+K ) - mda w p ) distribution, as shown in Fig. 2, returns a yield of 19 6 events, a AM
of 1046.72 t 0.6 MeV/c2, an aa width of 15.31[j4 2.5 MeV/c2. The statistical significance of
the signal is over 5u. The mass of Y(4140) is above open charm production and the width favors
a strong decay. The relative branching fraction between B+ -> Y(4140)K+, Y(4140) -> J/2pw and
Bv-> J/ia K+ is 15 5%.
An excess above the three-body phase space background shape appears at approximately 1.18
Gev/c2 in Fig. 2. Since the significance of Y(4140) is greater than 5u, we fit to the data assuming4
Juan Pablo F ERNAENDEZ
On behalf of CDF Collaboration
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Fernandez, Juan Pablo. B Lifetimes and X,Y,Z States at the Tevatron, article, May 25, 2011; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc829530/m1/4/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.