Search for the rare decay Adametz, A.; Adrover, C.; Ajaltouni, Z. ...
The journal of high energy physics,
14/1, Letnik:
2013, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A
bstract
A search for the decay
is performed, based on a data sample of 1.0 fb
−1
of pp collisions at
collected by the LHCb experiment at the Large Hadron Collider. The observed number of candidates ...is consistent with the background-only hypothesis, yielding an upper limit of
< 11(9)
×
10
−9
at 95 (90)% confidence level. This limit is a factor of thirty below the previous measurement.
A
bstract
The production of χ
b
(1
P
) mesons in
pp
collisions at a centre-of-mass energy of 7 TeV is studied using 32 pb
−1
of data collected with the LHCb detector. The χ
b
(1
P
) mesons are ...reconstructed in the decay mode χ
b
(1
P
) →
Υ
(1
S
)γ →
μ
+
μ
−
γ. The fraction of
Υ
(1
S
) originating from χ
b
(1
P
) decays in the
Υ
(1
S
) transverse momentum range 6
<
p
T
Υ
(1
S
)
<
15 GeV
/c
and rapidity range 2
.
0
< y
Υ (1S)
<
4
.
5 is measured to be
, where the first uncertainty is statistical, the second is systematic and the last gives the range of the result due to the unknown
Υ
(1
S
) and χ
b
(1
P
) polarizations.
A
bstract
A study of
and
D
0
K
+
final states is performed in a sample of 1.0 fb
−1
of
pp
collision data collected at a centre-of-mass energy of
with the LHCb detector. We confirm the existence of ...the
and
excited states and measure their masses and widths to be
A
bstract
The production of J/ψ mesons accompanied by open charm, and of pairs of open charm hadrons are observed in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity ...of 355 pb
−1
collected with the LHCb detector. Model independent measurements of absolute cross-sections are given together with ratios to the measured J/ψ and open charm cross-sections. The properties of these events are studied and compared to theoretical predictions.
A
bstract
The decay mode
allows for one of the theoretically cleanest measurements of the CKM angle γ through the study of time-dependent
CP
violation. This paper reports a measurement of its ...branching fraction relative to the Cabibbo-favoured mode
based on a data sample corresponding to 0.37 fb
−1
of proton-proton collisions at
collected in 2011 with the LHCb detector. In addition, the ratio of B meson production fractions
f
s
/f
d
, determined from semileptonic decays, together with the known branching fraction of the control channel
B
0
→
D
−
π
+
, is used to perform an absolute measurement of the branching fractions:
where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to
f
s
/f
d
.
A
bstract
Measurements of inclusive
W
and
Z
boson production cross-sections in
pp
collisions at
using final states containing muons are presented. The data sample corresponds to an integrated ...luminosity of 37 pb
−1
collected with the LHCb detector. The
W
and
Z
bosons are reconstructed from muons with a transverse momentum above 20 GeV/c and pseudorapidity between 2
.
0 and 4
.
5, and, in the case of the
Z
cross-section, a dimuon invariant mass between 60 and 120 GeV/c
2
. The cross-sections are measured to be 831 ± 9 ± 27 ± 29pb for
W
+
, 656 ± 8 ± 19 ± 23 for
W
−
and 76
.
7 ± 1
.
7 ± 3
.
3 ± 2
.
7pb for
Z
, where the first uncertainty is statistical, the second is systematic and the third is due to the luminosity. Differential cross-sections,
W
and
Z
cross-section ratios and the lepton charge asymmetry are also measured in the same kinematic region. The ratios are determined to be
and
. The results are in general agreement with theoretical predictions, performed at next-to-next-to-leading order in QCD using recently calculated parton distribution functions.
A
bstract
The production of
B
±
mesons in proton-proton collisions at
= 7 TeV is studied using 35 pb
−1
of data collected by the LHCb detector. The
B
±
mesons are reconstructed exclusively in the
B
±
...→
J/ψK
±
mode, with
J/ψ
→
μ
+
μ
−
. The differential production cross-section is measured as a function of the
B
±
transverse momentum in the fiducial region 0
< p
T
<
40 GeV
/
c and with rapidity 2
.
0
< y <
4
.
5. The total cross-section, summing up
B
+
and
B
−
, is measured to be
σ
(
pp
→
B
±
X,
0
< p
T
<
40 GeV
/
c
,
2
.
0
< y <
4
.
5) = 41
.
4 ± 1
.
5 (stat
.
) ± 3
.
1 (syst
.
)
μb
.
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