-
Belle Collaboration,
E. Solovieva,
R. Chistov,
I. Adachi,
D. M. Asner,
T. Aushev,
A. M. Bakich,
A. Bala,
V. Bhardwaj,
B. Bhuyan, [......],
Y. Watanabe,
K. M. Williams,
E. Won,
B. D. Yabsley,
Y. Yamashita,
S. Yashchenko,
Y. Yook,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: Using 121.4 fb^{-1} of data collected with the Belle detector at the Y(5S)
resonance at the KEKB asymmetric-energy e^+e^- collider, we report evidence for
the B_s^0 -> Lambda_c^+ Lambda-bar pi^- decay mode with a measured branching
fraction (3.6 +- 1.1[stat.] {+0.3 -0.5}[syst.] +- 0.9[Lambda_c^+] +-
0.7[N_{Bs}]) * 10^{-4} and a significance of 4.4 standard deviations. This is
the first evidence for a baryonic B_s^0 decay.
04/2013;
-
The Belle Collaboration,
V. Gaur, G. B. Mohanty,
T. Aziz,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko,
T. Aushev,
A. M. Bakich, [......],
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
B. D. Yabsley,
Y. Yamashita,
S. Yashchenko,
Y. Yusa,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report a search for charmless hadronic decays of neutral B mesons to the
final state K+K-pi0. The results are based on a 711 fb^-1 data sample that
contains 772x10^6 BB-bar pairs, and was collected at the Y(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We find the
first evidence for this decay with a significance of 3.5 standard deviations
and measure its branching fraction as BF(B0 --> K+K-pi0) = [2.17 +/- 0.60(stat)
+/- 0.24 (syst)]x10^-6.
04/2013;
-
Belle Collaboration,
V. Bhardwaj,
K. Miyabayashi,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko,
T. Aushev,
T. Aziz,
A. M. Bakich, [......],
J. Yamaoka,
Y. Yamashita,
S. Yashchenko,
Y. Yook,
C. Z. Yuan,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
V. Zhulanov,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report measurements of $B \to \chi_{c1} \gamma K$ and $\chi_{c2} \gamma K$
decays using $772 \times 10^{6}$ $B\bar{B}$ events collected at the
$\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy
$e^+e^-$ collider. Evidence of a new resonance in the $\chi_{c1} \gamma$ final
state is found with a statistical significance of $3.8 \sigma$. This state has
a mass of $3823.1 \pm 1.8 {(stat)} \pm 0.7 {(syst)}$ MeV/$c^2$, a value that is
consistent with theoretical expectations for the previously unseen $1^3 D_2$
$c\bar{c}$ meson. We find no other narrow resonance and set upper limits on the
branching fractions of the $X(3872) \to \chi_{c1} \gamma$ and $\chi_{c2}
\gamma$ decays.
04/2013;
-
Belle Collaboration,
Z. Q. Liu,
C. P. Shen,
C. Z. Yuan,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko,
T. Aushev,
T. Aziz, [......],
B. D. Yabsley,
J. Yamaoka,
Y. Yamashita,
S. Yashchenko,
Y. Yook,
Y. Yusa,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: The cross section for $e^+ e^- \to \pi^+ \pi^- J/\psi$ between 3.8 GeV and
5.5 GeV is measured with a 967 fb$^{-1}$ data sample collected by the Belle
detector at or near the $\Upsilon(nS)$ ($n = 1,\ 2,\ ...,\ 5$) resonances. The
Y(4260) state is observed, and its resonance parameters are determined. In
addition, an excess of $\pi^+ \pi^- J/\psi$ production around 4 GeV is
observed. This feature can be described by a Breit-Wigner parameterization with
properties that are consistent with the Y(4008) state that was previously
reported by Belle. In a study of $Y(4260) \to \pi^+ \pi^- J/\psi$ decays, a
structure is observed in the $M(\pi^\pm\jpsi)$ mass spectrum with $5.2\sigma$
significance, with mass $M=(3894.5\pm 6.6\pm 4.5) {\rm MeV}/c^2$ and width
$\Gamma=(63\pm 24\pm 26)$ MeV/$c^{2}$, where the errors are statistical and
systematic, respectively. This structure can be interpreted as a new charged
charmonium-like state.
03/2013;
-
O. Lutz,
S. Neubauer,
M. Heck,
T. Kuhr,
A. Zupanc,
I. Adachi,
H. Aihara,
D. M. Asner,
T. Aushev,
T. Aziz, [......],
P. Wang,
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
H. Yamamoto,
Y. Yamashita,
Z. P. Zhang,
V. Zhilich,
V. Zhulanov
[show abstract]
[hide abstract]
ABSTRACT: We report a search for the rare decays B -> h(*) nu nubar, where h(*) stands
for K+, Ks0, K*+, K*0, pi+, pi0, rho+, rho0 and phi. The results are obtained
from a 711 fb-1 data sample that contains 772 million BB pairs collected at the
Y(4S) resonance with the Belle detector at the KEKB e+e- collider. We search
for signal candidates by fully reconstructing a hadronic decay of the
accompanying B meson and requiring a single h(*) meson left on the signal side.
No significant signal is observed and we set upper limits on the branching
fractions at 90% confidence level. The measurements of B+ -> K*+ nu nubar, B+
-> pi+ nu nubar, B0 -> pi0 nu nubar and B0 -> rho^0 nu nubar provide the
world's currently most restrictive limits.
03/2013;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
R Loveless,
A Mohapatra,
M U Mozer,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb^{-1}, collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2±0.6(stat)±0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.
Physical Review Letters 02/2013; 110(8):081803. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a search for the pair production of third-generation scalar and vector leptoquarks, as well as for top squarks in R-parity-violating supersymmetric models. In either scenario, the new, heavy particle decays into a τ lepton and a b quark. The search is based on a data sample of pp collisions at sqrt[s]=7 TeV, which is collected by the CMS detector at the LHC and corresponds to an integrated luminosity of 4.8 fb^{-1}. The number of observed events is found to be in agreement with the standard model prediction, and exclusion limits on mass parameters are obtained at the 95% confidence level. Vector leptoquarks with masses below 760 GeV are excluded and, if the branching fraction of the scalar leptoquark decay to a τ lepton and a b quark is assumed to be unity, third-generation scalar leptoquarks with masses below 525 GeV are ruled out. Top squarks with masses below 453 GeV are excluded for a typical benchmark scenario, and limits on the coupling between the top squark, τ lepton, and b quark, λ_{333}^{'} are obtained. These results are the most stringent for these scenarios to date.
Physical Review Letters 02/2013; 110(8):081801. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
C Lazaridis,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: The polarizations of the Υ(1S), Υ(2S), and Υ(3S) mesons are measured in proton-proton collisions at sqrt[s]=7 TeV, using a data sample of Υ(nS)→μ^{+}μ^{-} decays collected by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb^{-1}. The dimuon decay angular distributions are analyzed in three different polarization frames. The polarization parameters λ_{ϑ}, λ_{φ}, and λ_{ϑφ}, as well as the frame-invariant quantity λ[over ˜], are presented as a function of the Υ(nS) transverse momentum between 10 and 50 GeV, in the rapidity ranges |y|<0.6 and 0.6<|y|<1.2. No evidence of large transverse or longitudinal polarizations is seen in the explored kinematic region.
Physical Review Letters 02/2013; 110(8):081802. · 7.37 Impact Factor
-
Belle Collaboration,
I. Adachi,
K. Adamczyk,
H. Aihara,
K. Arinstein,
Y. Arita,
D. M. Asner,
T. Aso,
V. Aulchenko,
T. Aushev, [......],
L. M. Zhang,
Z. P. Zhang,
L. Zhao,
V. Zhilich,
P. Zhou,
V. Zhulanov,
T. Zivko,
A. Zupanc,
N. Zwahlen,
O. Zyukova
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the time-dependent CP violation parameters in B0
-> pi+ pi- decays. The results are obtained from the final data sample
containing 772 million BBbar pairs collected at the Upsilon(4S) resonance with
the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the
CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03 (syst) and Scp =
-0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp represent direct and
mixing-induced CP violation, respectively. From an isospin analysis including
results from other Belle measurements, we rule out 23.8 < phi2 < 66.8 degrees
at the 1 sigma level.
02/2013;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Evidence is presented for the associated production of a single top quark and W boson in pp collisions at sqrt[s]=7 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 4.9 fb^{-1}. The measurement is performed using events with two leptons and a jet originated from a b quark. A multivariate analysis based on kinematic properties is utilized to separate the tt[over ¯] background from the signal. The observed signal has a significance of 4.0σ and corresponds to a cross section of 16_{-4}^{+5} pb, in agreement with the standard model expectation of 15.6±0.4_{-1.2}^{+1.0} pb.
Physical Review Letters 01/2013; 110(2):022003. · 7.37 Impact Factor
-
Belle Collaboration,
D. Liventsev,
I. Adachi,
H. Aihara,
K. Arinstein,
D. M. Asner,
V. Aulchenko,
T. Aushev,
A. M. Bakich,
A. Bay, [......],
Y. Watanabe,
K. M. Williams,
E. Won,
B. D. Yabsley,
H. Yamamoto,
Y. Yamashita,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report on a search for heavy neutrinos in B-meson decays. The results are
obtained using a data sample that contains 772x10^6 BB-bar pairs collected at
the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy
e+e- collider. No signal is observed and upper limits are set on mixing of
heavy neutrinos with left-handed neutrinos of the Standard Model in the mass
range 0.5 - 5.0 GeV/c^2.
01/2013;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
C Lazaridis,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: Results are presented from a search for heavy, right-handed muon neutrinos, N_{μ}, and right-handed W_{R} bosons, which arise in the left-right symmetric extensions of the standard model. The analysis is based on a 5.0 fb^{-1} sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected by the CMS detector at the Large Hadron Collider. No evidence is observed for an excess of events over the standard model expectation. For models with exact left-right symmetry, heavy right-handed neutrinos are excluded at 95% confidence level for a range of neutrino masses below the W_{R} mass, dependent on the value of M_{W_{R}}. The excluded region in the two-dimensional (M_{W_{R}}, M_{N_{μ}}) mass plane extends to M_{W_{R}}=2.5 TeV.
Physical Review Letters 12/2012; 109(26):261802. · 7.37 Impact Factor
-
Belle Collaboration,
C. Oswald,
P. Urquijo,
J. Dingfelder,
I. Adachi,
H. Aihara,
K. Arinstein,
D. M. Asner,
T. Aushev,
A. M. Bakich, [......],
M. Watanabe,
Y. Watanabe,
K. M. Williams,
E. Won,
H. Yamamoto,
Y. Yamashita,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We report a measurement of the inclusive semileptonic B_s^0 branching
fraction in a 121 fb^{-1} data sample collected near the Upsilon(5S) resonance
with the Belle detector at the KEKB asymmetric energy e^+ e^- collider. Events
containing B_s^0 pairs are selected by reconstructing a tag side D_s^+ and
identifying a signal side lepton l^+ (l = e, mu) that is required to have the
same-sign charge to ensure that both originate from different B_s^0 mesons. The
B_s^0 -> X^- l^+ nu branching fraction is extracted from the ratio of the
measured yields of D_s^+ mesons and D_s^+ l^+ pairs and the known production
and branching fractions. The inclusive semileptonic branching fraction is
measured to be [10.6 +/- 0.5(stat) +/- 0.7(syst)] %.
12/2012;
-
B. R. Ko,
E. Won,
I. Adachi,
H. Aihara,
K. Arinstein,
D. M. Asner,
T. Aushev,
A. M. Bakich,
K. Belous,
V. Bhardwaj, [......],
G. Varner,
C. H. Wang,
M. -Z. Wang,
P. Wang,
Y. Watanabe,
K. M. Williams,
Y. Yamashita,
C. C. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: We search for CP violation in the decay $D^+\rightarrow K^0_S K^+$ using a
data sample with an integrated luminosity of 977 fb$^{-1}$ collected with the
Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No CP violation
has been observed and the CP asymmetry in $D^+\rightarrow K^0_S K^+$ decay is
measured to be $(-0.25\pm0.28\pm0.14)%$, which is the most sensitive
measurement to date. After subtracting CP violation due to $K^0-\bar{K}^0$
mixing, the CP asymmetry in $D^+\rightarrow\bar{K}^0 K^+$ decay is found to be
$(+0.08\pm0.28\pm0.14)%$.
12/2012;
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: We report an investigation of the invariant mass spectrum of the two jets with highest transverse momentum in pp→W+2-jet and W+3-jet events to look for resonant enhancement. The data sample corresponds to an integrated luminosity of 5.0 fb^{-1} collected with the CMS detector at sqrt[s]=7 TeV. We find no evidence for the anomalous structure reported by the CDF Collaboration, and establish an upper limit of 5.0 pb at 95% confidence level on the production cross section for a generic Gaussian signal with mass near 150 GeV. Additionally, we exclude two theoretical models that predict a CDF-like dijet resonance near 150 GeV.
Physical Review Letters 12/2012; 109(25):251801. · 7.37 Impact Factor
-
D. Abbaneo,
G. Abbiendi,
M. Abbrescia,
S. Abdullin,
A. Abdulsalam,
B.S. Acharya,
D. Acosta,
J.G. Acosta,
A. Adair,
W. Adam, [......],
M.H. Zoeller,
O. Zorba,
P. Zotto,
W. Zou,
G. Zumerle,
M. Zupan,
A. Zuranski,
R. Zuyeuski,
M. Zvada,
P. Zych
[show abstract]
[hide abstract]
ABSTRACT: The Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and
has been the subject of numerous searches at accelerators around the world. Its discovery would verify the existence of a
complex scalar field thought to give mass to three of the carriers of the electroweak force—the W+, W–, and Z0 bosons—as well as to the fundamental quarks and leptons. The CMS Collaboration has observed, with a statistical significance
of five standard deviations, a new particle produced in proton-proton collisions at the Large Hadron Collider at CERN. The
evidence is strongest in the diphoton and four-lepton (electrons and/or muons) final states, which provide the best mass resolution
in the CMS detector. The probability of the observed signal being due to a random fluctuation of the background is about 1
in 3 × 106. The new particle is a boson with spin not equal to 1 and has a mass of about 1.25 giga–electron volts. Although its measured
properties are, within the uncertainties of the present data, consistent with those expected of the Higgs boson, more data
are needed to elucidate the precise nature of the new particle.
Science 12/2012; 338(6114):1569-1575. · 31.20 Impact Factor
-
I. Adachi,
K. Adamczyk,
H. Aihara,
K. Arinstein,
Y. Arita,
D. M. Asner,
T. Aso,
V. Aulchenko,
T. Aushev,
T. Aziz, [......],
L. M. Zhang,
Z. P. Zhang,
L. Zhao,
V. Zhilich,
P. Zhou,
V. Zhulanov,
T. Zivko,
A. Zupanc,
N. Zwahlen,
O. Zyukova
[show abstract]
[hide abstract]
ABSTRACT: We present a study of the branching fraction of the decay B^0 -> rho^0 rho^0
and the fraction of longitudinally polarized \rho^0 mesons in this decay. The
results are obtained from the final data sample containing $772 \times 10^{6}$
$B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle
detector at the KEKB asymmetric-energy e^+e^- collider. We find $166 \pm 59$
B^0 -> rho^0 rho^0 events, corresponding to a branching fraction of ${\cal
B}(B^0 -> rho^0 rho^0) = (1.02\pm 0.30 (\rm stat) \pm 0.22 (\rm syst))\times
10^{-6} $ with a longitudinally polarization fraction $f_L =
0.21^{+0.18}_{-0.22} (\rm stat) \pm 0.11 (\rm syst)$. The branching fraction's
upper limit is ${\cal B}(B^0 -> rho^0 rho^0) < 1.5 \times 10^{-6}$ at 90%
confidence level. We use the longitudinal polarization fraction to determine
the Cabibbo-Kobayashi-Maskawa matrix angle $\phi_2 = (91.0 \pm 7.2)^{\circ}$
through an isospin analysis in the $B\to\rho\rho$ system. We furthermore obtain
${\cal B}(B^0 -> rho^0 f_0) \times {\cal B}(f_0 -> \pi^+\pi^-) = (0.86 \pm 0.27
(\rm stat) \pm 0.15 (\rm syst))\times 10^{-6}$, corresponding to $149 \pm 49$
$B^0 -> rho^0 f_0$ events with a significance of 3.0 standard deviations and
upper limits at 90% confidence level on the (product) branching fractions for
possible decays with the same final state, ${\cal B}(B^0 -> pi^+\pi^-pi^+\pi^-)
< 11.7 \times 10^{-6} $, ${\cal B}(B^0 -> rho^0 pi^+\pi^-) < 12.2 \times
10^{-6}$, ${\cal B}(B^0 -> f_0 pi^+\pi^-) \times {\cal B}(f_0->\pi^+\pi^-) <
3.1 \times 10^{-6}$ and ${\cal B}(B^0 -> f_0 f_0) \times {\cal
B}(f_0->\pi^+\pi^-)^{2} < 0.2 \times 10^{-6}$.
12/2012;
-
R Mizuk,
D M Asner,
A Bondar,
T K Pedlar,
I Adachi,
H Aihara,
K Arinstein,
V Aulchenko,
T Aushev,
T Aziz, [......],
M Watanabe,
Y Watanabe,
K M Williams,
E Won,
B D Yabsley,
J Yamaoka,
Y Yamashita,
C Z Yuan,
Z P Zhang,
V Zhilich
[show abstract]
[hide abstract]
ABSTRACT: We report the first evidence for the η_{b}(2S) using the h_{b}(2P)→η_{b}(2S)γ transition and the first observation of the h_{b}(1P)→η_{b}(1S)γ and h_{b}(2P)→η_{b}(1S)γ transitions. The mass and width of the η_{b}(1S) and η_{b}(2S) are measured to be m_{η_{b}(1S)}=(9402.4±1.5±1.8) MeV/c^{2}, m_{η_{b}(2S)}=(9999.0±3.5_{-1.9}^{+2.8}) MeV/c^{2}, and Γ_{η_{b}(1S)}=(10.8_{-3.7-2.0}^{+4.0+4.5}) MeV. We also update the h_{b}(1P) and h_{b}(2P) mass measurements. We use a 133.4 fb^{-1} data sample collected at energies near the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider.
Physical Review Letters 12/2012; 109(23):232002. · 7.37 Impact Factor
-
S Chatrchyan,
V Khachatryan,
A M Sirunyan,
A Tumasyan,
W Adam,
E Aguilo,
T Bergauer,
M Dragicevic,
J Erö,
C Fabjan, [......],
J Leonard,
R Loveless,
A Mohapatra,
I Ojalvo,
F Palmonari,
G A Pierro,
I Ross,
A Savin,
W H Smith,
J Swanson
[show abstract]
[hide abstract]
ABSTRACT: The suppression of the individual Υ(nS) states in PbPb collisions with respect to their yields in pp data has been measured. The PbPb and pp data sets used in the analysis correspond to integrated luminosities of 150 μb^{-1} and 230 nb^{-1}, respectively, collected in 2011 by the CMS experiment at the LHC, at a center-of-mass energy per nucleon pair of 2.76 TeV. The Υ(nS) yields are measured from the dimuon invariant mass spectra. The suppression of the Υ(nS) yields in PbPb relative to the yields in pp, scaled by the number of nucleon-nucleon collisions, R_{AA}, is measured as a function of the collision centrality. Integrated over centrality, the R_{AA} values are 0.56±0.08(stat)±0.07(syst), 0.12±0.04(stat)±0.02(syst), and lower than 0.10 (at 95% confidence level), for the Υ(1S), Υ(2S), and Υ(3S) states, respectively. The results demonstrate the sequential suppression of the Υ(nS) states in PbPb collisions at LHC energies.
Physical Review Letters 11/2012; 109(22):222301. · 7.37 Impact Factor
-
Belle Collaboration,
X. L. Wang,
Y. L. Han,
C. Z. Yuan,
C. P. Shen,
P. Wang,
I. Adachi,
H. Aihara,
D. M. Asner,
V. Aulchenko, [......],
C. H. Wang,
J. Wang,
M. -Z. Wang,
K. M. Williams,
E. Won,
Y. Yamashita,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
A. Zupanc
[show abstract]
[hide abstract]
ABSTRACT: The cross section for e^+e^- \to \eta J/\psi between \sqrt{s}=3.8 GeV/c^2 and
5.3 GeV/c^2 is measured via initial state radiation using 980 fb^{-1} of data
on and around the \Upsilon(nS)(n=1,2,3,4,5) resonances collected with the Belle
detector at KEKB. Two resonant structures at the \psi(4040) and \psi(4160) are
observed in the \eta J/\psi invariant mass distribution. Fitting the mass
spectrum with the coherent sum of two Breit-Wigner functions, one obtains
BR(\psi(4040)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4040)} = (4.8\pm0.9\pm1.4)
eV and BR(\psi(4160)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4160)} =
(4.0\pm0.8\pm1.4) eV for one solution and BR(\psi(4040)\to\eta
J/\psi)\cdot\Gamma_{ee}^{\psi(4040)} = (11.2\pm1.3\pm1.9) eV and
BR(\psi(4160)\to\eta J/\psi)\cdot\Gamma_{ee}^{\psi(4160)} = (13.8\pm1.3\pm2.0)
eV for the other solution, where the first errors are statistical and the
second are systematic. This is the first measurement of this hadronic
transition mode of these two states, and the partial widths to \eta J/\psi are
found to be about 1 MeV. There is no evidence for the Y(4260), Y(4360),
\psi(4415), or Y(4660) in the \eta J/\psi final state, and upper limits of
their production rates in e^+e^- annihilation are determined.
10/2012;
