The results of search for new decays of beauty baryons in the LHCb experiment are presented. In particular the new decays Λ
b
0
→ψ(2
S
)
pπ
−
,
Λ
b
0
→
Λ
c
+
p
p
¯
π
−
, Λ
b
0
→
pK
−
π
+
π
−
, Λ
b
0
...→
pK
−
K
+
K
−
, Ξ
b
0
→
pK
−
π
+
π
−
, Ξ
b
0
→
pK
−
π
+
K
−
are observed and ratios of branching fractions are measured. The results are based on the proton-proton collisions data collected by the LHCb experiment at the Large Hadron Collider.
The first ever observation of the decay process
B
0
→
J
/ψη′ is described. The branching ratios were measured for the decay processes
B
(s)
→ J/ψη(′), and the η–η′ mixing angles were determined on ...this basis. The first indication of the occurrence of the decay process
B
s
→ ψ(2
S
)η′ is presented. The respective analysis was performed on the basis of data accumulated with the LHCb detector in proton–proton collisions at the c.m. collision energies of 7 and 8 TeV and the integrated luminosity of 3 fb
−1
.
The calibration of the LHCb electromagnetic calorimeter is a multistep procedure aimed at reconstructing photon and electron energies to a precision not poorer than 2%. A method based on measuring ...the neutral-pion invariantmass is applied at the last step of this procedure. A regular application of this method makes it possible to improve substantially the resolution for particles that decay through channels featuring electrons and photons in the final state.
Calibration of the electromagnetic calorimeter for the LHCb experiment is aimed at measuring the electron and photon energies with an accuracy of 2% or better. A number of calibration techniques are ...sequentially used for this purpose. One of these techniques is based on reconstruction of the π
0
meson invariant mass in a two-photon decay. Using this procedure, it is possible to calibrate the electromagnetic calorimeter in the transverse energy range of 300–1500 MeV. An important advantage of this technique is its independence of the states of the other LHCb spectrometer systems. Statistics sufficient for attaining the declared purpose can be rapidly acquired owing to the large cross section of neutral pion production in deep inelastic events. The algorithm has been implemented as a part of the LHCb software. The calibration procedure using neutral pions takes no more than 2 weeks and helps achieve the required accuracy.
The reconstruction efficiency of photons and neutral pions is measured using the relative yields of reconstructed
B
+
→
J
/ψ
K
*
+
(→
K
+
π
0
) and
B
+
→
J
/ψ
K
+
decays. The efficiency is studied ...using the data set, corresponding to an integrated luminosity of 3 fb
–1
, collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV.
The precise calibration of an electromagnetic calorimeter is extremely important for flavor tagging and for the study of
B
-mesons decays and therefore is of great importance for implementing the ...physics program of the LHCb experiment. The purpose of the calibration process is to achieve a 2% accuracy when measuring the energies of electrons and photons. At the last step of a multi-stage procedure, the method of restoring the invariant mass of a neutral pion in its decay into two photons is used.
The calibration and performance of the LHCb Calorimeter system in Run 1 and 2 at the LHC are described. After a brief description of the sub-detectors and of their role in the trigger, the ...calibration methods used for each part of the system are reviewed. The changes which occurred with the increase of beam energy in Run 2 are explained. The performances of the calorimetry for \(\gamma\) and \(\pi^0\) are detailed. A few results from collisions recorded at \(\sqrt {s}\) = 7, 8 and 13 TeV are shown.
The results of treatment of data obtained in the SERP-E-184experiment "Investigation of mechanisms of the production of charmed particles in proton-nucleus interactions at 70 GeV and their decays" by ...irradiating the active target of the SVD-2 facility consisting of carbon, silicon, and lead plates, are presented. After separating a signal from the two-particle decay of neutral charmed mesons and estimating the cross section for charm production at a threshold energy {\sigma}(cč)=7.1 \pm 2.4(stat.) \pm 1.4(syst.) \mub/nucleon, some properties of D mesons are investigated. These include the dependence of the cross section on the target mass number (its A dependence); the behavior of the differential cross sections d{\sigma}/dpt2 and d{\sigma}/dxF; and the dependence of the parameter {\alpha} on the kinematical variables xF, pt2, and plab. The experimental results in question are compared with predictions obtained on the basis of the FRITIOF7.02 code.
The results of data handling for E-184 experiment obtained with 70 GeV proton beam irradiation of active target with carbon, silicon and lead plates are presented. Two-prongs neutral charmed D0 and ...Ď0 -mesons decays were selected. Signal / background ratio was (51+/-17) / (38+/-13). Registration efficiency for mesons was defined and evaluation for charm production cross section at threshold energy is presented: sigma(cĉ) = 7.1 +/- 2.4(stat.) +/- 1.4(syst.) (\mu/nucleon).
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