12 research outputs found
First observation of a doubly charged tetraquark and its neutral partner
A combined amplitude analysis is performed for the decays and , which are
related by isospin symmetry. The analysis is based on data collected by the
LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8
and 13. The full data sample corresponds to an integrated
luminosity of 9. Two new resonant states with masses of
and widths of
are observed, which decay to and
respectively. The former state indicates the first observation of
a doubly charged open-charm tetraquark state with minimal quark content
, and the latter state is a neutral tetraquark composed of
quarks. Both states are found to have spin-parity ,
and their resonant parameters are consistent with each other, which suggests
that they belong to an isospin triplet.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-026.html (LHCb
public pages
Search for the doubly heavy baryon decaying to
A first search for the
decay is performed by the LHCb experiment with a data sample of proton-proton
collisions, corresponding to an integrated luminosity of
recorded at centre-of-mass energies of 7, 8, and . Two peaking structures are seen with a local (global) significance of
and standard deviations at masses of
and , respectively. Upper limits are set on the baryon
production cross-section times the branching fraction relative to that of the
decay at centre-of-mass energies of 8 and
, in the and in the
rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to
, respectively. Upper limits are presented
as a function of the mass and lifetime.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-005.html (LHCb
public pages
Amplitude analysis of and decays
Resonant contributions in and
decays are determined with an amplitude
analysis, which is performed both separately and simultaneously, where in the
latter case isospin symmetry between the decays is assumed. The analysis is
based on data collected by the LHCb detector in proton-proton collisions at
center-of-mass energies of 7, 8 and 13 . The full data sample
corresponds to an integrated luminosity of 9 . A doubly charged
spin-0 open-charm tetraquark candidate together with a neutral partner, both
with masses near , are observed in the decay channel.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-027.html (LHCb
public pages
Searches for rare B-s(0) and B-0 decays into four muons
Searches for rare and decays into four muons are performed
using proton-proton collision data recorded by the LHCb experiment,
corresponding to an integrated luminosity of 9 . Direct decays
and decays via light scalar and resonances are considered. No evidence
for the six decays searched for is found and upper limits at the 95% confidence
level on their branching fractions ranging between and
are set
Two-component bacterial regulation systems: Targets of a search for new antibacterial drugs
Constraints on the CKM angle gamma from B-+/- -> Dh(+/-) decays using D -> h(+/-)h'(-/+)pi(0) final states
A data sample collected with the LHCb detector corresponding to an integrated luminosity of 9 fb(-1) is used to measure eleven CP violation observables in B-+/- -> Dh(+/-) decays, where h is either a kaon or a pion. The neutral D meson decay is reconstructed in the three-body final states: K-+/-pi(-/+)pi(0); pi(+)pi(-)pi(0); K+ K- pi(0) and the suppressed pi K-+(-/+)pi(0) combination. The mode where a large CP asymmetry is expected, B-+/- -> [K-+/-pi(-/+)pi(0)] K-D(+/-), is observed with a significance greater than seven standard deviations. The ratio of the partial width of this mode relative to that of the favoured mode, B-+/- -> [K-+/-pi(-/+)pi(0)] K-D(+/-), is R-ADS(K) = (1.27 +/- 0.16 +/- 0.02) x 10(-2). Evidence for a large CP asymmetry is also seen: A(ADS(K)) = - 0.38 +/- 0.12 +/- 0.02. Constraints on the CKM angle gamma are calculated from the eleven reported observables
Precision measurement of forward boson production in proton-proton collisions at TeV
A precision measurement of the boson production cross-section at TeV in the forward region is presented, using collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb. The production cross-section is measured using events within the fiducial region defined as pseudorapidity GeV/ for both muons and dimuon invariant mass GeV/. The integrated cross-section is determined to be \begin{equation*} \sigma(Z\rightarrow\mu^+\mu^-) = 195.3 \pm 0.2 \pm 1.5 \pm 3.9~pb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions, including a prediction at next-to-next-to-leading order in perturbative quantum chromodynamics and a prediction with resummation
Observation of → D+pπ−π− and → D*+pπ−π− decays
AbstractThe multihadron decays
Λ
b
0
→ D+pπ−π− and
Λ
b
0
→ D*+pπ−π− are observed in data corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay
Λ
b
0
→
Λ
c
+
π+π−π− as a normalisation channel, the ratio of branching fractions is measured to be
B
Λ
b
0
→
D
+
p
π
−
π
−
B
Λ
b
0
→
Λ
c
0
π
+
π
−
π
−
×
B
D
+
→
K
−
π
+
π
+
B
Λ
c
0
→
pK
−
π
−
=
5.35
±
0.21
±
0.16
%
,
where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the
Λ
b
0
→ D*+pπ−π− and
Λ
b
0
→ D+pπ−π− decays is found to be
B
Λ
b
0
→
D
∗
+
p
π
−
π
−
B
Λ
b
0
→
D
+
p
π
−
π
−
×
B
D
∗
+
→
D
+
π
0
+
B
D
∗
+
→
D
+
γ
=
61.3
±
4.3
±
4.0
%
.
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