A
bstract
The forward-backward charge asymmetry for the process
q
q
¯
→
Z
/
γ
∗
→
μ
+
μ
−
is measured as a function of the invariant mass of the dimuon system. Measurements are performed using proton ...proton collision data collected with the LHCb detector at
s
=
7
and 8 TeV, corresponding to integrated luminosities of 1 fb
−1
and 2 fb
−1
respectively. Within the Standard Model the results constrain the effective electroweak mixing angle to be
sin
2
θ
W
eff
=
0.23142
±
0.00073
±
0.00052
±
0.00056
,
where the first uncertainty is statistical, the second systematic and the third theoretical. This result is in agreement with the current world average, and is one of the most precise determinations at hadron colliders to date.
The LHCb measurement of the lifetime ratio of the Λb0 baryon to the B¯0 meson is updated using data corresponding to an integrated luminosity of 3.0 fb−1 collected using 7 and 8 TeV centre-of-mass ...energy pp collisions at the LHC. The decay modes used are Λb0→J/ψpK− and B¯0→J/ψπ+K−, where the π+K− mass is consistent with that of the K¯⁎0(892) meson. The lifetime ratio is determined with unprecedented precision to be 0.974±0.006±0.004, where the first uncertainty is statistical and the second systematic. This result is in agreement with original theoretical predictions based on the heavy quark expansion. Using the current world average of the B¯0 lifetime, the Λb0 lifetime is found to be 1.479±0.009±0.010 ps.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).Measurements are presented of electroweak boson production using data from pp collisions at a centre-of-mass energy of ... ...TeV. The analysis is based on an integrated luminosity of 2.0 fb super(-1) recorded with the LHCb detector. The bosons are identified in the W arrow right mu nu and Z arrow right mu super(+) mu super(-) decay channels. The cross-sections are measured for muons in the pseudorapidity range 2.0 < eta < 4.5, with transverse momenta p sub(T) > 20 GeV/c and, in the case of the Z boson, a dimuon mass within ... GeV/c super(2). The results are ... ... ... ... ... ... ... ... where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. The evolution of the W and Z boson cross-sections with centre-of-mass energy is studied using previously reported measurements with 1.0 fb super(-1) of data at 7 TeV. Differential distributions are also presented. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Figure not available: see fulltext.
A search for CP violation in D± → η'π± and Ds± → η'π± decays is performed using proton–proton collision data, corresponding to an integrated luminosity of 3 fb–1, recorded by the LHCb experiment at ...centre-of-mass energies of 7 and 8 TeV.
A
bstract
The differential branching fraction with respect to the dimuon invariant mass squared, and the
CP
asymmetry of the
B
±
→
π
±
μ
+
μ
−
decay are measured for the first time. The CKM matrix ...elements |
V
td
| and |
V
ts
|, and the ratio |
V
td
/V
ts
| are determined. The analysis is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb
−1
, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The total branching fraction and
CP
asymmetry of
B
±
→
π
±
μ
+
μ
−
decays are measured to be
ℬ
B
±
→
π
±
μ
+
μ
−
=
1.83
±
0.24
±
0.05
×
10
−
8
and
A
C
P
B
±
→
π
±
μ
+
μ
−
=
−
0.11
±
0.12
±
0.01
,
where the first uncertainties are statistical and the second are systematic. These are the most precise measurements of these observables to date, and they are compatible with the predictions of the Standard Model.
The ratio of branching fractions RK/π≡B(B+c→J/ψK+)/B(B+c→J/ψπ+) is measured with pp collision data collected by the LHCb experiment at centre-of-mass energies of 7 TeV and 8 TeV, corresponding to an ...integrated luminosity of 3 fb−1. It is found to be R K/π = 0.079 ± 0.007 ± 0.003, where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the previous LHCb result, while the uncertainties are significantly reduced.
A
bstract
The ratio of branching fractions and the difference in
CP
asymmetries of the decays
B
+
→
J/ψπ
+
and
B
+
→
J/ψK
+
are measured using a data sample of
pp
collisions collected by the LHCb ...experiment, corresponding to an integrated luminosity of 3 fb
−1
at centre-of-mass energies of 7 and 8 TeV. The results are
ℬ
B
+
→
J
/
ψ
π
+
ℬ
B
+
→
J
/
ψ
K
+
=
3.83
±
0.03
±
0.03
×
10
−
2
,
A
C
P
B
+
→
J
/
ψ
π
+
−
A
C
P
B
+
→
J
/
ψ
K
+
=
1.82
±
0.86
±
0.14
×
10
−
2
,
where the first uncertainties are statistical and the second are systematic. Combining this result with a recent LHCb measurement of
A
C
P
B
+
→
J
/
ψ
K
+
provides the most precise estimate to date of
CP
violation in the decay
B
+
→
J/ψπ
+
,
A
C
P
B
+
→
J
/
ψ
π
+
=
1.91
±
0.89
±
0.16
×
1
0
−
2
.
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