Magnetic distortion calibration for LHCb RICH detectors Xing, Funai
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
The LHCb experiment will search for new physics in CP violation and rare decays from heavy flavour production at the LHC. Particle identification is provided by two Ring Imaging Cherenkov (RICH) ...detectors, which incorporate a total of 484 Hybrid Photon Detectors (HPDs).
The RICH detectors are located in the fringe field of the LHCb dipole magnet and fields as large as 2.5
mT have been measured in some regions occupied by the RICH 1 photodetectors. It is necessary to make corrections for the distortion of the ring-images measured by the HPDs. RICH 1 incorporates a magnetic calibration system comprising a series of collimated LEDs mounted on
x–
y stages which scan over the front-faces of the HPD arrays. A similar system based on commercial projectors is used on RICH 2. The calibration is performed in dedicated runs with dipole field on and off. The calibration parameters are then stored in the Conditions Database and applied to the LHC collision data reconstruction. This report will present the improvement in Cherenkov angular resolutions with the magnetic calibration.
A
bstract
A precision measurement of the
Z
boson production cross-section at
$$ \sqrt{\mathrm{s}} $$
s
= 13 TeV in the forward region is presented, using
pp
collision data collected by the LHCb ...detector, corresponding to an integrated luminosity of 5.1 fb
−
1
. The production cross-section is measured using
Z → μ
+
μ
−
events within the fiducial region defined as pseudorapidity 2
.
0
< η <
4
.
5 and transverse momentum
p
T
>
20 GeV
/c
for both muons and dimuon invariant mass 60
< M
μμ
<
120 GeV
/c
2
. The integrated cross-section is determined to be
$$ \sigma \left(Z\to {\mu}^{+}{\mu}^{-}\right)=196.4\pm 0.2\pm 1.6\pm 3.9\ \mathrm{pb}, $$
σ
Z
→
μ
+
μ
−
=
196.4
±
0.2
±
1.6
±
3.9
pb
,
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 within uncertainties.
Search for the decay B0→ ϕμ+μ Alfonso Albero, A.; Anderlini, L.; Bachmayer, M. ...
The journal of high energy physics,
11/5, Letnik:
2022, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
A search for the decay
B
0
→ ϕμ
+
μ
−
is performed using proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV collected by the LHCb experiment and corresponding to an ...integrated luminosity of 9 fb
−
1
. No evidence for the
B
0
→ ϕμ
+
μ
−
decay is found and an upper limit on the branching fraction, excluding the
ϕ
and charmonium regions in the dimuon spectrum, of 4
.
4
×
10
−
3
at a 90% credibility level, relative to that of the
B
s
0
→ ϕμ
+
μ
−
decay, is established. Using the measured
B
s
0
→ ϕμ
+
μ
−
branching fraction and assuming a phase-space model, the absolute branching fraction of the decay
B
0
→ ϕμ
+
μ
−
in the full
q
2
range is determined to be less than 3
.
2
×
10
−
9
at a 90% credibility level.
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