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LHCb Posters

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2022-12-09
17:13
LHCb - Search for the decay Ξ−b(Ω−b)Λh−h′− at LHCb
Reference: Poster-2022-1094
Created: 2022. -1 p
Creator(s): Pagare, Bhagyashree

It is of great interest to search for the phenomenon of CP violation in the decays of b baryons given that a significant amount of CP violation has been observed in b meson decays. This motivates searches for new decay modes of the Xib and Omegab baryons and studies of their production properties. In this analysis we search for decays that will be helpful to control the systematics in future CP violation studies. The results would help to increase the knowledge about b baryon production and decays. In addition, studies of the resonant structure of the multibody decays provide new insights into charm baryon spectroscopy

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
16:03
LHCb - Luminosity measurements and PLUME detector at LHCb
Reference: Poster-2022-1093
Created: 2022. -1 p
Creator(s): Spedicato, Eugenia

Luminosity measurement is a fundamental parameter for all the experiments. The LHCb detector works at a lower luminosity with respect to CMS and ATLAS. It is done by tuning the distance between the two colliding beams according to the measurement of instantaneous luminosity from hardware-based trigger counters. The upgraded LHCb detector operates at fivefold instantaneous luminosity compared to the previous runs, and it has a fully software-based trigger. Consequently, a new approach to the luminosity measurement is adopted. New counters have been introduced for Run 33. Additionally, in order to verify linearity from calibration to data taking conditions, per-fill emittance scans are performed. For the first time, a new detector capable of measuring the LHC luminosity has been installed at the interaction point of LHCb. It is named Probe for LUminosity MEasurement - PLUME. It enables real time monitoring of beam condition parameters and it provides both online and offline luminosity measurements

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:27
LHCb - Search for W/Z boson rare deacy at LHCb
Reference: Poster-2022-1092
Created: 2022. -1 p
Creator(s): Han, Qundong

The large production cross-sections of W and Z bosons at hadron colliders offer unique opportunities to search for their rare decays. W/Z boson rare decay can be used to test the Standard Model(SM) and probe for physics beyond SM, and provide stringent tests of the quantum chromodynamics(QCD) factorization formalism. Predictions of their branching fractions using the QCD factorization range from $10^{-6}$ to $10^{-12}$. A search for the rare decays $W^{+}→D^{+}_{s} \gamma$ and $Z→D^{0} \gamma$ is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 2.0 fb^{-1}. No significant signal is observed for either decay mode and upper limits on their branching fractions are set.

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:25
LHCb - The VELO Looks for Vertices but Who Looks after the VELO?
Reference: Poster-2022-1091
Created: 2022. -1 p
Creator(s): Mohammed, Rizwaan Adeeb

The Vertex Locator (VELO) is the innermost part of the LHCb detector, positioned around 3.5mm from the collision region, inside the LHC vacuum. For safety, both halves are held away from the beams during injection. Then, each half reconstructs the position of the primary vertices, allowing the VELO to close and centre around the colliding beams. The VELO closes in several stages, with safety criteria being automatically checked at each stage. The VELO was closed for the first time in Run 3 in October. Using initial data taken from the first closing, we can study the shape of the RF foil from hadronic interactions with the material. This can be compared to the design position, and can also be used to verify that the VELO is well centred around the beams

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:21
LHCb - The LHCb RICH System Upgrade Commissioning
Reference: Poster-2022-1090
Created: 2022. -1 p
Creator(s): Franzoso, Edoardo

The LHCb Ring-Imaging Cherenkov (RICH) system is essential for Particle Identification (PID) of charged hadrons in the momentum range 2–100 GeV/c: it consists of an upstream detector (RICH 1), located close to the interaction point, and a downstream detector (RICH 2), placed after the tracking system. The LHCb experiment has been upgraded to deal with a five-fold increase in instantaneous luminosity, up to $2 \times 10^{33}\; cm^{-2}\; s^{-1}$, and to read out data at a rate of 40 MHz during RUN3. Both RICH detectors have been upgraded to maintain and excellent PID with a redesigned opto-electronic chain and new photon detectors. In addition, RICH 1 has a modified layout with new mechanics and spherical mirrors to reduce the maximum occupancy. The RICH system has taken part in all stable beams collisions throughout 2022. The RICH detectors are currently fully functional, time aligned, and integrated into the run control with all the other LHCb sub-detectors. The first data taken in the nominal RUN3 conditions seem promising and preliminary studies show an improved or equal PID performance compared to the one achieved in RUN2. An overview of the LHCb RICH system commissioning campaign is given, following all the steps from the first quality assurance measurements up to the current status of the detectors in the LHCb cavern

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:17
LHCb - Commissioning of the LHCb’s first level trigger
Reference: Poster-2022-1089
Created: 2022. -1 p
Creator(s): Scarabotto, Alessandro

The LHCb’s Upgrade 1 aims to record 25 $fb^{-1}$ in Run3-4 with an increased luminosity of $2 \times 10^{33} cm^{-2} s^{-1}$, a factor 5 compared to Run1-2. The upgrade features a completely new DAQ system with a full software trigger. The reconstruction of events is performed at 30 MHz LHC non-empty pp collision rate, with around 5 TB/s of input data. To cope with this very high amount of input, the first high level trigger (HLT1) is fully based on Graphics Processing Units (GPU) in order to exploit their parallelisation power and achieve an output rate of 1 MHz. The poster presents the first year of the HLT1 commissioning with its many achievements.

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:10
LHCb - Commissioning of the LHCb Scintillating Fibre Tracker
Reference: Poster-2022-1088
Created: 2022. -1 p
Creator(s): Wang, Chishuai

During upgrade 1 of the LHCb detector, the Scintillating Fibre (SciFi) Tracker was installed downstream of LHCb's dipole magnet. The SciFi tracker consists of three stations with four layers for each. It uses scintillating fibres for the active area and silicon photomultiplier arrays for the readout. Its front-end electronics has been designed to support the 40 MHz readout. The commissioning of the SciFi tracker is currently ongoing. This poster provides a brief description of the SciFi tracker, its working principle and its front-end electronics. First commissioning results are presented.

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
15:07
LHCb - HLTs & Alignment and Calibration at LHCb
Reference: Poster-2022-1087
Created: 2022. -1 p
Creator(s): Valls Canudas, Nuria

The data volume generated from the LHCb detector reaches 5TB/s in Run 3 conditions. In order to record data to permanent storage, this volume needs to be reduced by a factor 400. To achieve this, the trigger system makes a full reconstruction of events and a selection of specific signals of interest in an approach called real-time analysis. After the first stage of the trigger (HLT1), the second stage (HLT2) performs an offline-quality reconstruction and selection of physics signatures. There are four main components in this reconstruction phase: charged particle pattern recognition, Kalman fit, calorimeter reconstruction and particle identification. After the reconstruction is performed, the selection is made using different selection algorithms tuned for a specific signal topology or analysis. This process is enabled thanks to the quasi-real-time alignment and calibration, which provides the most accurate parameters for reconstruction and selections to provide the best possible resolution of physics parameters and maximize the selection efficiency.

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
14:56
LHCb - Angular analyses of $b\rightarrow s\ell^+ \ell^-$ decays at LHCb
Reference: Poster-2022-1086
Created: 2022. -1 p
Creator(s): Volle, Felicia Carolin

The Standard Model (SM) of Particle Physics is in contradiction with cosmological observables as it does not provide a dark matter candidate or provide a description of the observed matter-antimatter asymmetry in the universe. In order to address these puzzles, New Physics is required and the study of processes at higher scales could help to reveal their nature and interaction mechanisms. Therefore, it is important to shape the landscape of possible NP scenarios. While the direct searches at colliders are limited by the center-of-mass energy, rare processes are suitable for indirect searches of NP. Among them, the $b \to s \ell^+ \ell^-$ transitions are highly sensitive to NP effects and they are accessible with the existing data. The LHCb experiment reported tensions with the SM in $b \to s \ell^+ \ell^-$ transitions, observing a coherent and consistent pattern in different exclusive decay modes of $b$-hadrons produced at the LHC. Those measurements have been performed in $B^+$, $B^0$ and $B_s^0$ decays and the study of $b$-baryon decays can provide additional and complementary information. Angular analyses of $b \to s \ell^+ \ell^-$ transitions allow the characterization of potential NP affecting the decay properties. The ongoing angular analysis in the $\Lambda_b \to \Lambda(1520)\mu^+\mu^-$ decay is presented. An angular fit to the decay is presented to extract observables sensitive to NP. The decay mode with available LHCb data is statistically limited and It would greatly benefit from the increase of the luminosity expected in the coming years with the Run III data taking at the LHCb experiment.

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Conference - 12th LHC students poster session, CERN, Geneva
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2022-12-09
14:46
LHCb - Charm mixing in D0 → K±π∓π±π∓
Reference: Poster-2022-1085
Created: 2022. -1 p
Creator(s): Smallwood, Jennifer Clare

Measurements of the charm-meson mixing and CP-violation parameters are important tests of the Standard Model and any deviations observed could hint at New Physics. A measurement of the time-dependent ratio of $D^0 \rightarrow K^+ \pi^- \pi^+ \pi^-$ to $D^0 \rightarrow K^- \pi^+ \pi^- \pi^+$ decays using prompt LHCb data would improve the precision on these observables. Moreover, knowledge can be gained about the hadronic parameters that describe the $D^0 \rightarrow K^\pm \pi^\mp \pi^\pm \pi^\mp$ decays, which are important inputs in a measurement of the CKM angle using $B \rightarrow D K, D^0 \rightarrow K^\pm \pi^\mp \pi^\pm \pi^\mp$ decays. This poster presents the methodology of the study, and the expected sensitivity to the parameters of interest.

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Conference - 12th LHC students poster session, CERN, Geneva
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