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Experimental Particle Physics with the LHCb detector at Cern

English title Experimental Particle Physics with the LHCb detector at Cern
Applicant Straumann Ulrich
Number 159948
Funding scheme Project funding
Research institution Physik-Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Particle Physics
Start/End 01.04.2015 - 31.03.2017
Approved amount 1'104'660.00
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Keywords (9)

pp collisions; LHC; b quark; CP violation; new physics; CKM Matrix; Standard Model; B meson; LHCb

Lay Summary (German)

Das LHCb-Experiment am Large Hadron Collider (LHC) des CERN beschäftigt sich unter anderem mit der Suche nach Unterschieden zwischen Materie und Anti-Materie sowie der indirekten Suche nach neuen Elementarteilchen und der Untersuchung der Struktur von Protonen und Atomkernen.
Lay summary

Das LHCb-Experiment besteht aus einem der vier Detektoren am Large Hadron Collider (LHC) des CERN und wird von einer Kollaboration aus 69 Instituten betrieben. Sein Hauptfokus liegt in der Untersuchung von Teilchen, welche in den Proton-Kollisionen entstehen und Beauty- oder Charm-Quarks enthalten. Solche Teilchen können benutzt werden um die CP-Verletzung, welche den Unterschied zwischen Materie und Anti-Materie beschreibt, sowie Seltene Zerfälle zu untersuchen. 

Die LHCb-Gruppe der Universität Zürich spielt eine Hauptrolle in der Untersuchung dieser Zerfälle. Dabei werden deren Rate und Dynamik gemessen. Diese Messungen können mit theoretischen Vorhersagen des Standard Modells, welches die Dynamik der bekannten Elementarteilchen beschreibt, verglichen werden. Abweichungen zwischen den Messungen und den theoretischen Vorhersagen weisen dabei auf die Existenz zusätzlicher Elementarteilchen hin. 

Weiter führt die Gruppe Messungen durch, welche dazu dienen können, die Struktur des Protons sowie Atomkerne besser zu bestimmen. Hierzu wird die Produktion von W- und Z-Bosonen in Proton-Proton- und Proton-Blei-Kollisionen untersucht. 

Die LHCb-Gruppe der Universität Zürich beteiligt sich auch am Betrieb der siliziumbasierten Spurdetektoren des Experiments, bei deren Aufbau sie eine führende Rolle gespielt hat. Diese Detektoren vermessen die Flugbahn von geladenen Teilchen und dienen der Messung des Teilchenimpulses. Im Hinblick auf die Weiterentwicklung des LHC ist eine Verbesserung dieser Detektoren in LHCb geplant. Dabei soll wiederum ein Detektor aus Siliziumsensoren verwendet werden. Momentan arbeitet die Gruppe an der Evaluierung von möglichen Sensoren sowie der Entwicklung derer Ausleseelektronik. 


Direct link to Lay Summary Last update: 20.04.2015

Responsible applicant and co-applicants



Group / person Country
Types of collaboration
LHCb Kollaboration Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Associated projects

Number Title Start Funding scheme
154217 FLARE: Maintenance & Operation for the LHC Experiments 2014 01.04.2014 FLARE
146644 Experimental Particle Physics with the LHCb detector at Cern 01.04.2013 Project funding
166208 High Precision CP Violation Physics at LHCb 01.04.2016 Project funding
173580 FLARE 2017-2020: Operation and upgrade of the LHCb experiment 01.04.2017 FLARE
178969 LHCb experiment at CERN: Detector Upgrades and Analyses with Electroweak Bosons 01.06.2018 Project funding
172637 Experimental Particle Physics with the LHCb detector at Cern 01.04.2017 Project funding
166915 FLARE 2016: Operation and upgrade of the LHCb experiment 01.04.2016 FLARE
154218 FLARE 2014-2015: Operation and upgrade of the LHCb experiment 01.04.2014 FLARE
146644 Experimental Particle Physics with the LHCb detector at Cern 01.04.2013 Project funding


The LHCb experiment [1] is designed to perform precision measurements of CP violating observablesand rare decays of heavy quarks at the LHC. By measuring numerous decay modes of b and c hadrons,it performs consistency checks of the Standard Model of particle physics and searches for signs ofphysics beyond the Standard Model. Moreover, the unique detector layout and triggering capabilitiesas well as an excellent momentum resolution give access to a wide range of interesting measurementsin the fields of particle production and spectroscopy.The first physics run (run 1) of the LHC has been a great success for LHCb. Data were routinelycollected at twice the design instantaneous luminosity and more than 93% of the luminosity deliveredby the LHC were recorded with high quality. This allowed the experiment to collect samples of protonprotoncollisions good for physics analyses, corresponding to integrated luminosities of 1 fb-1 at theLHC collision energy of 7 TeV in 2011 and 2 fb-1 at 8 TeV in 2012. Smaller data samples of leadprotonand proton-lead collisions at a collision energy of 2.76 TeV per nucleon were collected in 2013.More than 220 scientific papers have already been published or submitted to peer-reviewed scientificjournals. Many more results are expected from ongoing analyses. World-best measurements have beenachieved in many observables, including LHCb’s key analyses. Almost all results obtained so far arein good agreement with predictions from the Standard Model of particle physics and put stringentconstraints on the possible parameter space of New Physics models.LHCb is making use of the currently ongoing long shutdown of the LHC (LS 1) to perform minormaintenance work on detector components and to revise the software trigger (HLT) strategy with aview to collect data even more efficienctly during the upcoming second physics run (run 2). Duringrun 2, which is scheduled to start in 2015 and last for about three years, the LHC is foreseen todeliver proton-proton collisions at a collision energy of 13 TeV. The higher collision energy is expectedto yield a factor of two improvement in the bb production rate. The goal of LHCb for run 2 is tocollect an additional 5 fb-1 in integrated luminosity. As current LHCb results are limited by statisticaluncertainties, significant improvements resulting in more stringent tests of the Standard Model andNew Physics are expected from the analysis of this larger dataset.To reach measurement precisions approaching theory uncertainties in key observables, the LHCb collaborationprepares an upgrade of the experiment, which is foreseen to be installed during the secondlong LHC shutdown (LS 2) in 2018/2019. The upgraded LHCb should collect 50 fb-1 in 10 years, withsignificantly improved trigger efficiencies for hadronic final states.The Zurich group has been actively involved in LHCb since 1999. We made a significant contributionto the design and construction of the current detector, we play a leading role in physics analyses and inthe optimization of reconstruction algorithms, and we make important contributions to the operationof the detector and to the LHCb upgrade effort.Members of our group continue to occupy leadership positions within the collaboration. KatharinaM¨uller currently serves as convener of the QCD, Electroweak and Exotica physics working groupwhile Olaf Steinkamp has recently been appointed as deputy project leader for the new UpstreamTracker. Earlier, Ulrich Straumann served as chair of the LHCb collaboration board from 2008 till 2012, Olaf Steinkamp has been a member of the LHCb Speakers' Bureau since the beginning of 2011 and was chairing it in 2012. Several members of our group have chaired analysis working groups within LHCb,