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.
In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, |Vub| and |Vcb|, are governed by the coupling of the quarks to the Higgs boson. Using ...data from the LHCb experiment at the Large Hadron Collider, the probability for the Λb0 baryon to decay into the p final state relative to the final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of |Vcb|, the first |Vub| measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of |Vub| using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states.
A search for CP violation in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays is performed using pp collision data, corresponding to an integrated luminosity of 3 fb(-1), collected using the LHCb detector at ...center-of-mass energies of 7 and 8 TeV. The flavor of the charm meson is inferred from the charge of the pion in D*(+) -> D-0 pi(+) and D*(-) -> (D) over bar (0)pi(-) decays. The difference between the CP asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays, Delta A(CP) A(CP)(K-K+) - A(CP)(pi(-)pi(+)), is measured to be -0.10 +/- 0.08(stat) +/- 0.03(syst)%. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.
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