I will review a selection of LHCb results on the production of heavy quarkonium states in pp collisions, including recent results on J/psi and Upsilon(nS)(n = 1, 2, 3) production at radicals = 8 TeV, ...as well as preliminary results on J/psi production in proton-lead collisions at radicals sub(NN) = 5 TeV.
A
bstract
The relative production rate of
$ B_s^0 $
and
B
0
mesons is determined with the hadronic decays
$ B_s^0\to D_s^{-}{\pi^{+}} $
and
B
0
→
D
−
K
+
. The measurement uses data corresponding to ...1.0 fb
−1
of
pp
collisions at a centre-of-mass energy of
$ \sqrt{s}=7 $
TeV recorded in the forward region with the LHCb experiment. The ratio of production rates,
f
s
/f
d
, is measured to be 0
.
238 ± 0
.
004 ± 0
.
015 ± 0
.
021, where the first uncertainty is statistical, the second systematic, and the third theoretical. This is combined with a previous LHCb measurement to obtain
f
s
/f
d
= 0
.
256 ± 0
.
020. The dependence of
f
s
/f
d
on the transverse momentum and pseudorapidity of the
B
meson is determined using the decays
$ B_s^0\to D_s^{-}{\pi^{+}} $
and
B
0
→
D
−
π
+
. There is evidence for a decrease with increasing transverse momentum, whereas the ratio remains constant as a function of pseudorapidity. In addition, the ratio of branching fractions of the decays
B
0
→
D
−
K
+
and
B
0
→
D
−
π
+
is measured to be 0
.
0822 ± 0
.
0011 (stat) ± 0
.
0025 (syst).
Observation of the decay → J/ψ K+K−π Adinolfi, M.; Albrecht, J.; Anderlini, L. ...
The journal of high energy physics,
12/11, Letnik:
2013, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
The decay
→
J/ψK
+
K
−
π
+
is observed for the first time, using protonproton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3 fb
−1
. A signal ...yield of 78 ± 14 decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of
→
J/ψK
+
K
−
π
+
decays to that of
→
J/ψπ
+
decays is measured to be 0
.
53 ± 0
.
10 ± 0
.
05, where the first uncertainty is statistical and the second is systematic.
The CP-violating charge asymmetry in B±→ϕK± decays is measured in a sample of pp collisions at 7 TeV centre-of-mass energy, corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb ...experiment. The result is ACP(B±→ϕK±)=0.022±0.021±0.009, where the first uncertainty is statistical and the second systematic. In addition, a search for the B±→ϕπ± decay mode is performed, using the B±→ϕK± decay rate for normalization. An upper limit on the branching fraction B(B±→ϕπ±)<1.5×10−7 is set at 90% confidence level.
The data sample of Λ0b→J/ψpK− decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1, is inspected for the presence of J/ψp or ...J/ψK− contributions with minimal assumptions about K−p contributions. It is demonstrated at more than nine standard deviations that Λ0b→J/ψpK− decays cannot be described with K−p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P+c→J/ψp charmonium-pentaquark states in the same data sample.
A full amplitude analysis of Λ0b→J/ψpπ− decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1. A ...significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ−, either the Pc(4380)+ and Pc(4450)+→J/ψp states, previously observed in Λ0b→J/ψpK− decays, or the Zc(4200)−→J/ψπ− state, previously reported in B0→J/ψK+π− decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the Pc(4380)+ and Pc(4450)+ production rates expected from their previous observation taking account of Cabibbo suppression.
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