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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 172637
Funding scheme Project funding
Research institution Physik-Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Particle Physics
Start/End 01.04.2017 - 30.09.2018
Approved amount 502'593.00
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Keywords (10)

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

Lay Summary (German)

Lead
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. Die Designphase dieses neun Detektors ist mehr oder weniger abgeschlossen, die eigentliche Konstruktion wird in diesem Jahr starten.

 

 

Direct link to Lay Summary Last update: 26.04.2017

Responsible applicant and co-applicants

Employees

Publications

Publication
Testing lepton flavour universality in semileptonic Λb → Λc* decays
Böer Philipp, Bordone Marzia, Graverini Elena, Owen Patrick, Rotondo Marcello, van Dyk Danny (2018), Testing lepton flavour universality in semileptonic Λb → Λc* decays, in Journal of High Energy Physics, 2018(6), 155-155.
First measurement of the CP-violating phase ϕ s d d ¯ $$ {\phi}_s^{d\overline{d}} $$ in Bs0 → (K+π−)(K−π+) decays
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Appleby R. B., Archilli F., d’Argent P., et al. (2018), First measurement of the CP-violating phase ϕ s d d ¯ $$ {\phi}_s^{d\overline{d}} $$ in Bs0 → (K+π−)(K−π+) decays, in Journal of High Energy Physics, 2018(3), 140-140.
First observation of forward Z→bb¯ production in pp collisions at s=8 TeV
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A.A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J.E., Appleby R.B., Archilli F., d'Argent P., et al. (2018), First observation of forward Z→bb¯ production in pp collisions at s=8 TeV, in Physics Letters B, 776, 430-439.
Test of lepton universality with B 0 → K *0 ℓ + ℓ − decays
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A. A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J. E., Appleby R. B., Archilli F., d’Argent P., Arnau Romeu J., et al. (2017), Test of lepton universality with B 0 → K *0 ℓ + ℓ − decays, in Journal of High Energy Physics, 2017(8), 55-55.
Measurement of forward tt‾ , W+bb¯ and W+cc¯ production in pp collisions at s=8 TeV
Aaij R., Adeva B., Adinolfi M., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Ali S., Alkhazov G., Alvarez Cartelle P., Alves A.A., Amato S., Amerio S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Andrews J.E., Appleby R.B., Archilli F., d'Argent P., Arnau Romeu J., et al. (2017), Measurement of forward tt‾ , W+bb¯ and W+cc¯ production in pp collisions at s=8 TeV, in Physics Letters B, 767, 110-120.

Communication with the public

Communication Title Media Place Year
Other activities Particle physics master classes for Gymnasium pupils German-speaking Switzerland 2018

Associated projects

Number Title Start Funding scheme
173580 FLARE 2017-2020: Operation and upgrade of the LHCb experiment 01.04.2017 FLARE
166915 FLARE 2016: Operation and upgrade of the LHCb experiment 01.04.2016 FLARE
159948 Experimental Particle Physics with the LHCb detector at Cern 01.04.2015 Project funding
166914 FLARE: Maintenance & Operation for the LHC Experiments 2016 01.04.2016 FLARE

Abstract

In contrast to direct searches at colliders, which are excluding several of what we thought were the best candidates to complete the Standard Model (SM), at present there are three anomalies in the flavour sector which are attracting large attention in the particle physics community. These anomalies might have a common new physics explanation. They consist of the angular observable P5' in the decay B->K*mm, measured by LHCb; the ratio of branching ratios RK, measured by LHCb; and the ratio of branching ratios of the semileptonic decays R(D(*)) , measured by the BaBar, Belle and LHCb collaborations. It is evident that the LHCb experiment is having a huge impact in the field. In addition to rapidly improving the measurements of the B-factories, LHCb is now exploring new intriguing territories in the landscape of flavour physics. Our group is one of the leading groups in the LHCb experiment in physics analysis, operation of the detector and hardware. For this reason we have had several important management roles within the collaboration during the years, including several working group convenerships and chair of collaboration board and speaker bureau.We were involved in the analysis of P5' (in collaboration with the Group of Prof. Serra at UZH). We had a major role in the electroweak forward physics at LHCb, thanks to the effort of Dr. K. Muller. In addition, we had an important role in the measurement of the branching ratio of the decay Bs->mm, which was one of the most anticipated measurements at LHC. The main focus of the coming years concerning the analysis will be a set of measurements that will allow to shed light into one of the most intriguing puzzles of experimental particle physics at the moment, i.e. the R(D()) anomaly, which at present deviates from the SM prediction about 4sigmas. Concerning the operation of the LHCb detector, we are deeply involved in the running of the current LHCb experiment. First of all Dr. B. Storaci is the Operation Coordinator (OC) of the LHCb experiment which is a key responsibility. The OC has to assure that all the acquisition chain of data in the experiment functions properly. They supervise all steps of the data taking, from the raw data taken in the pit to the calibration and the preselection (known as “stripping” inside the LHCb experiment) that delivers the data for all analyses. Therefore, it is often the case that problems of various nature have to be solved in a timely and efficient way. In addition, being the group that built the Tracker Turicensis (TT), we are participating in the operation and continuous monitoring of the Silicon Tracker of LHCb. We will continue with these responsibilities for the rest of RUN2. Finally, we are involved in the upgrade of the LHCb experiment, in particular in the design and construction of the Upstream Tracker (UT), which will be crucial for the trigger. In the UT project we are involved in tests of silicon sensors and readout electronics.With this SNF request we ask for the prolongation of our two postdoctoral researchers (Dr. M. Chrzaszcz and Dr. B. Storaci) and funding for four Ph.D. students. This will allow Mr. A. Weiden and Ms. E. Graverini to complete their Ph.D. and will allow the replacement of Mr. E. Bowen and Mr. M. Tresch who will graduate by the end of 2017. This request will not only allow us to keep the commitments we have in the LHCb experiment, but also to have a large impact in the physics analysis. In particular, we will focus on a set of measurements that will clarify the current = anomaly in semileptonic decays (R(D)). It is important to mention Prof. U. Straumann will retire the 31st July 2018, the Department of Physics of the University of Zurich is actively looking for a successor who will continue this LHCb research program. A candidate has already been selected and the procedure will shortly conclude, presumably early in 2017. This will assure continuity to the group and to the research program of LHCb at University of Zurich. This SNF funding request is therefore crucial to guarantee that our group does not lose the leading role in the LHCb experiment that we achieved during the years.
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