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Posters

Derniers ajouts:
2020-06-05
16:18
LHCb - Open Heavy-Flavour and $J/\psi$ production in peripheral PbPb collisions at LHCb
Reference: Poster-2020-1034
Created: 2020. -1 p
Creator(s): Belin, Samuel

In 2018, LHCb recorded ~210 microbarn$^{-1}$ integrated luminosity of PbPb collisions at $\sqrt(s_{NN})$ = 5.02 TeV. Although limited to peripheral hadronic collisions, this new dataset offers unique opportunities to study simultaneously open and close heavy flavor production, at forward rapidity down to zero pT, at the LHC. Moreover, with an increase of the luminosity by a factor 20 compared to the previous 2015 PbPb dataset, precise measurements on photo-produced charmonia in ultra-peripheral collisions are foreseen. All these measurements are sensitive to and would help to constrain the small-x parton distribution functions (nPDFs) in the target nucleus. Finally, the great momentum resolution of the detector allows to study photo-produced $J/\psi$ in collisions with a nuclear overlap. This new type of prob is sensitive to the geometry of the collisions but also to the electromagnetic field of the Pb nuclei. In this talk, we present the latest results on heavy flavor productions obtained by LHCb measurements in peripheral and ultra-peripheral PbPb collisions. Prospectives on this first results are also discussed.

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Conference - 10th edition of the Hard and Electromagnetic Probes
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2020-02-25
16:16
Lepton universality tests with Rare Decays at LHCb
Reference: Poster-2020-1033
Created: 2020. -1 p
Creator(s): Moise, Razvan-Daniel

Recent measurements of b-hadron decays involving leptons are in tension with the Standard Model (SM). Each of these so-called flavour anomalies diverge by up to 3 standard deviations from their SM predictions. There are various new physics scenarios (e.g. leptoquarks) which can explain the anomalies in a coherent fashion. Although some tensions could be due to theory uncertainties, certain observables are immune to such ambiguities. Such is the case for branching fraction ratios R(H) = B(Xb→H𝜇+𝜇-)/B(Xb→He+e-), where Xb is a beauty hadron, and H is a hadronic system. This poster presents the latest LHCb results on the ratios R(K) [PRL 122 (2019) 191801], R(K*0) [JHEP 08 (2017) 055], and R(pK) [arXiv:1912.08139].

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LHCb poster
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2020-02-25
15:31
Prospects for using sub-nanosecond time information to improve the LHCb RICH performance
Reference: Poster-2020-1032
Created: 2020. -1 p
Creator(s): Keizer, Floris

The increase in luminosity during the LHC upgrade programme causes a rise in particle multiplicity and hit occupancy in the LHCb detector. To mitigate this effect for the Ring-Imaging Cherenkov (RICH) detectors, it is proposed to use the photon detector hit time information. The excellent intrinsic time resolution of the RICH detectors of less than 10 ps was demonstrated in the LHCb simulation framework. The FPGA in the RICH detector readout chain includes a programmable time gate of 3 to 6 ns, which will be fine-tuned with the first data in 2021. This nanosecond time gate within the 25 ns readout is unprecedented in the LHC and will reduce background. During Upgrade Ib, the electronic readout chain can be modified or replaced in order to achieve a time resolution around 300 ps. For the high-luminosity environment during LHC Run 5, a further improvement in time resolution to approximately 50 to 100 ps is foreseen. The clear trend of improving particle ID performance with time resolution is presented in this poster.

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LHCb poster
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2020-02-24
11:37
Flavour Tagging at the LHCb Experiment
Reference: Poster-2020-1031
Created: 2020. -1 p
Creator(s): Fuhring, Quentin

Decay-time-dependent measurements of $B$ mesons require knowledge of the initial $B$ flavour. At LHCb an ensemble of various Flavour Tagging algorithms is used to determine the initial $B$ flavour. The higher luminosity in LHC Run 3 will be challenging for the LHCb Flavour Tagging and is expected to show an impact on the Flavour Tagging performance. As an alternative to the existing ensemble of Flavour Tagging algorithms an inclusive Flavour Tagging algorithm is under development. This inclusive tagger uses a recurrent neural network to estimate the initial $B$ flavour by evaluating all tracks of an event.

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LHCb poster
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2020-02-21
15:09
LHCb - Measurement of CP violation in B0→D∗±D∓ decays at LHCb
Reference: Poster-2020-1030
Created: 2020. -1 p
Creator(s): Ibis, Philipp

The decay-time-dependent \ensuremath{C\!P} asymmetry in $B^0 \to D^{*\pm}D^{\mp}$ decays is measured using a data set corresponding to an integrated luminosity of $9$\ensuremath{\fb^{-1}} recorded by the \lhcb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and $13$\aunit{Te\kern -0.1em V}. The analysis provides the most precise single measurement of \ensuremath{C\!P} violation in this decay channel to date. All parameters are consistent with their current world average values.

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2020-02-21
14:08
LHCb - Doubly charmed baryon searches and studies at LHC
Reference: Poster-2020-1029
Created: 2020. -1 p
Creator(s): Seman Bobulska, Dana

We present the latest results on the doubly charmed baryon searches and studies performed at the LHCb experiment. Precise studies of the properties of the doubly charmed baryon $\Xi_{cc}^{++}$, such as its lifetime, production, mass and decays, are presented. Recent search for its isospin partner, $\Xi_{cc}^{+}$ baryon, in $\Lambda_{c}^{+} K^{-} \pi^{+}$ decays using full Run1+Run2 data sample collected by the LHCb experiment, where no significant signal has been observed and upper limit on the production cross section times branching fraction with respect to the $\Xi_{cc}^{++} \rightarrow \Lambda_{c}^{+} K^{-} \pi^{+} \pi^{+}$ decay has been set, is discussed. Finally, ongoing studies and analyses are described, namely searches for the $\Xi_{cc}^{+}$ and $\Omega_{cc}^{+}$ baryons in more decay channels and preparation for Run3 data taking.

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LHCb poster
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2020-02-21
12:14
LHCb - Construction of the Upstream Tracker for the LHCb Upgrade
Reference: Poster-2020-1028
Created: 2020. -1 p
Creator(s): Ely, Scott Edward

The Upstream Tracker (UT) for the LHCb upgrade is currently being constructed. The UT, which sits just upstream of the dipole magnets, will enable a fast determination of track momentum so that slow tracks will not have to be subject to the downstream tracking. This will allow the fully software trigger to speed up by a factor of three. Modules consisting of a silicon sensor, hybrid flex circuit, and SALT ASIC are being fabricated at INFN Milano and at Syracuse University. After testing electronically for quality assurance, completed modules are then mounted on to supporting staves, also built at Syracuse. Finally, the fully populated staves are shipped to CERN to be installed in the experiment.

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LHCb poster
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2020-02-21
11:13
LHCb - Measurement of $|V_{cb}|$ with semileptonic Bs decays at LHCb
Reference: Poster-2020-1027
Created: 2020. -1 p
Creator(s): Manuzzi, Daniele

The measurement of the magnitude of the $V_{cb}$ element of the Cabibbo-Kobayashi-Maskawa matrix is of great importance in the validation of the Standard Model of particle physics. The current world averages for the inclusive and exclusive measurements of $|V_{cb}|$ are approximately three standard deviations apart, representing a long-standing puzzle in flavour physics. This poster presents the measurement of $|V_{cb}|$ using semileptonic $B_s^0$ decays produced in proton-proton collision data collected with the LHCb detector during the Run1 of the LHC. This is the first determination of $|V_{cb}|$ from exclusive decays at a hadron collider and the first using decays of the $B_s^0$ meson.

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LHCb poster
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2020-02-21
10:46
LHCb - Updated measurement of decay-time-dependent CP asymmetries in D0→K+K− and D0→π+π− decays at LHCb
Reference: Poster-2020-1026
Created: 2020. -1 p
Creator(s): Unverzagt, Daniel Joachim

The measurement of the decay-time dependent charge parity (CP) asymmetry in $\D^0 \to \pi^+ \pi^-$ and $\D^0 \to K^+ K^-$ is presented using proton-proton collisions. The data was recorded at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 $fb^{-1}$, with the LHCb detector. Neutral $D$ mesons which arise from semi-leptonic decays of b-flavoured hadrons are used.

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LHCb poster
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2020-02-21
10:41
LHCb - SMOG2 reconstruction performance: fixed-target physics at the LHCb experiment from Run3¶
Reference: Poster-2020-1025
Created: 2020. -1 p
Creator(s): Manuzzi, Daniele

The LHCb experiment started in 2015 a pioneering fixed-target pro- gramstudyingthecollisionsbetweenLHCprotonsandgastargetsinjected into the LHC beam pipe through a system called SMOG. The gas was free to spread between a wide area covering the pp luminous region, limiting the injectable gas species to noble ones. Fixed-target data were mostly acquired during special runs of limited duration to avoid interfering with the pp physics program. The upgrade of the SMOG program, SMOG2, will mainly consist in the installation of a confinement cell for the gas cov- ering a 20 cm long region upstream the nominal pp interaction point. This will allow to increase the gas density by up to two orders of magnitude and to potentially extend the gas species to be injected. Moreover, the large separation between the pp and SMOG2 regions opens the scenario of a simultaneous data-taking, provided that the reconstruction perfor- mance of both fixed-target and pp events is not significantly affected and the tight time constraints for the online reconstruction and selection are met. This poster contains some preliminary results for the efficiencies of the Run3 tracking sub-detectors: the performance are demonstrated to be comparable between pp and SMOG2 collisions and they do not degrade for pp when adding Helium or Argon gas targets

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