Study of the doubly charmed tetraquark Tcc Abdelmotteleb, A. S. W; Ajaltouni, Z; Andreianov, A ...
Nature communications,
12/2022, Letnik:
13, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and ...mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar Tcc+ tetraquark with a quark content of ccu¯d¯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector Tcc+ state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the Tcc+ state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.The existence and properties of tetraquark states with two heavy quarks and two light antiquarks have been widely debated. Here, the authors use a unitarized model to study the properties of an exotic narrow state compatible with a doubly charmed tetraquark.
LHCb is the dedicated heavy flavour experiment at the Large Hadron Collider at CERN. The partially assembled silicon vertex locator (VELO) of the LHCb experiment has been tested in a beam test. The ...data from this beam test have been used to determine the performance of the VELO alignment algorithm. The relative alignment of the two silicon sensors in a module and the relative alignment of the modules has been extracted. This alignment is shown to be accurate at a level of approximately
2
μ
m
and
0.1
mrad
for translations and rotations, respectively, in the plane of the sensors. A single hit precision at normal track incidence of about
10
μ
m
is obtained for the sensors. The alignment of the system is shown to be stable at better than the
10
μ
m
level under air to vacuum pressure changes and mechanical movements of the assembled system.
A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450
GeV/
c protons were collided on a beam absorber during the LHC synchronisation tests of the ...anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of
5
μ
m
in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than
10
μ
m
.
The modules for the Vertex Locator detector of the LHCb experiment represent a technical challenge for their complexity. The design of the sensors uses a complex double metal routing of the ...connection to the read-out strips and a high density of metal lines has to be accommodated in the module. The detectors are n-side read-out to be able to survive the highest radiation damage of any micro-strip sensor used in LHC experiments. The present choice is n-strips on n-type substrates (n-in-n geometry). Double-sided lithography is required, which impact on the cost of the devices and on the module construction. Moreover, the compact size of the hybrid imposes sophisticated technical solutions for cooling the electronics and the detector. The module construction and the possible benefits offered by the choice of p-type substrate detectors compared to the present n-in-n devices are here discussed in details.
First LHC beam induced tracks reconstructed in the LHCb VELO Parkes, C.; Borghi, S.; Bates, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2009, Letnik:
604, Številka:
1
Journal Article
Recenzirano
The Vertex Locator of the LHCb experiment has been used to fully reconstruct beam induced tracks at the LHC. A beam of protons was collided with a beam absorber during the LHC synchronisation test of ...the anti-clockwise beam on the weekend 22nd–24th August 2008. The resulting particles have been observed by the Vertex Locator. The LHCb Vertex Locator is a silicon micro-strip detector containing 21 planes of modules. Tracks were observed passing through up to 19 modules (38 silicon sensors). A total of over 700 tracks were reconstructed, and are being used to study the calibration and alignment of the detector.
A
bstract
Coherent production of
J/ψ
mesons is studied in ultraperipheral lead-lead collisions at a nucleon-nucleon centre-of-mass energy of 5 TeV, using a data sample collected by the LHCb ...experiment corresponding to an integrated luminosity of about 10 μb
−1
. The
J/ψ
mesons are reconstructed in the dimuon final state and are required to have transverse momentum below 1 GeV. The cross-section within the rapidity range of 2
.
0
< y <
4
.
5 is measured to be 4
.
45 ± 0
.
24 ± 0
.
18 ± 0
.
58 mb, where the first uncertainty is statistical, the second systematic and the third originates from the luminosity determination. The cross-section is also measured in
J/ψ
rapidity intervals. The results are compared to predictions from phenomenological models.
The LHCb vertex detector Bowcock, T.; Parkes, C.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/1999, Letnik:
435, Številka:
1
Journal Article
Recenzirano
LHCb is a dedicated LHC experiment for precision measurements of CP-violation and rare decays in the B meson sector. Achieving excellent resolution on the production and decay vertices of b-hadrons ...is vital to this programme. The design of the vertex detector is reviewed, the development programme outlined, and results from the first prototype detectors are provided.
A
bstract
A precision measurement of the
Z
boson production cross-section at
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
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.
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