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B Meson Decays and Lepton Flavour Universality Violation

English title B Meson Decays and Lepton Flavour Universality Violation
Applicant Crivellin Andreas
Number 176884
Funding scheme SNSF Professorships
Research institution Physik-Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Theoretical Physics
Start/End 01.01.2019 - 31.12.2022
Approved amount 1'516'179.00
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All Disciplines (2)

Discipline
Theoretical Physics
Particle Physics

Keywords (9)

Lepton flavour violation; Lepton Flavour Universality Violation; Higher dimensional operators; Physics beyond the Standard Model; Loop calculations; B meson decays; Flavour; Dark Matter; Effective Field Theories

Lay Summary (German)

Lead
Die fundamentalen Bausteine der Materie (Fermionen) kommen in drei Generationen genannt "Flavour" vor. Teilchen unterschiedlichen Flavours unterscheiden sich nur durch ihre Masse, ansonsten haben sie identische Eigenschaften. Z.B. das Muon welches in der kosmischen Strahlung vorkommt, ist die schwere Version des Elektrons. Die Flavourphysik untersucht die Übergänge zwischen verschiedenen Generationen. Dazu werden die Vorhersagen des Standardmodells der Teilchenphysik mit den experimentellen Messungen verglichen. Eventuelle Differenzen deuten dabei auf neue Physik, also auf neue, noch unentdeckte Teilchen hin.
Lay summary

Ziel und Inhalt des Forschungsprojekts

Das übergeordnete Ziel des Forschungsprojekts ist ein detaillierteres Verständnis des Einflusses neuer Physik in Flavourobservablen sowohl im Lepton- als auch im Quarksektor. Das Forschungsprojekt beschäftigt sich hierbei besonders mit den Hinweisen auf neue Physik welche in den letzten Jahren in B Meson Zerfallen gefunden wurden. Zum einen werden Modelle neuer Physik konstruiert. Zum anderen werden in diesen Modellen Observablen berechnet und eine phänomenologische Analyse durchgeführt. Eine Verknüpfung mit Dunkler Materie ist angedacht.

Wissenschaftlicher und Gesellschaftlicher Kontext

Dieses Projekt trägt zum tieferen wissenschaftlichen Verständnis der fundamentalen Wechselwirkungen zwischen den Materieteilchen bei. Dadurch können die experimentellen Ergebnisse der Hochenergie- (LHC) und der Präzisions-Teilchenphysik (MEG, BELLE II, etc.) gedeutet werden, was einen signifikanten Einfluss auf unser Weltbild hat.

Direct link to Lay Summary Last update: 23.10.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Modified lepton couplings and the Cabibbo-angle anomaly
Manzari Claudio Andrea, Coutinho Antonio M., Crivellin Andreas (2021), Modified lepton couplings and the Cabibbo-angle anomaly, in PoS, LHCP2020, 242-242, PoS, Trieste LHCP2020, 242-242.
A new precision process at FCC-hh: the diphoton leptonic Wh channel
Bishara Fady, Englert Philipp, Grojean Christophe, Montull Marc, Panico Giuliano, Rossia Alejo N. (2020), A new precision process at FCC-hh: the diphoton leptonic Wh channel, in Journal of High Energy Physics, 2020(7), 75-75.
$Z^\prime$ models with less-minimal flavour violation
Calibbi Lorenzo, Crivellin Andreas, Kirk Fiona, Manzari Claudio Andrea, Vernazza Leonardo (2020), $Z^\prime$ models with less-minimal flavour violation, in Phys. Rev. D, 101(9), 095003-095003.
Correlating $ε^\prime/ε$ to hadronic $B$ decays via $U(2)^3$ flavour symmetry
Crivellin Andreas, Gross Christian, Pokorski Stefan, Vernazza Leonardo (2020), Correlating $ε^\prime/ε$ to hadronic $B$ decays via $U(2)^3$ flavour symmetry, in Phys. Rev. D, 101(1), 015022-015022.
Flavor Phenomenology of the Leptoquark Singlet-Triplet Model
Crivellin Andreas, Müller Dario, Saturnino Francesco (2020), Flavor Phenomenology of the Leptoquark Singlet-Triplet Model, in JHEP, 06, 020-020.
Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly
Coutinho Antonio M., Crivellin Andreas, Manzari Claudio Andrea (2020), Global Fit to Modified Neutrino Couplings and the Cabibbo-Angle Anomaly, in Phys. Rev. Lett., 125(7), 071802-071802.
Hadronic Vacuum Polarization: $(g-2)_μ$ versus Global Electroweak Fits
Crivellin Andreas, Hoferichter Martin, Manzari Claudio Andrea, Montull Marc (2020), Hadronic Vacuum Polarization: $(g-2)_μ$ versus Global Electroweak Fits, in Phys. Rev. Lett., 125(9), 091801-091801.
Leptoquarks in oblique corrections and Higgs signal strength: status and prospects
Crivellin Andreas, Müller Dario, Saturnino Francesco (2020), Leptoquarks in oblique corrections and Higgs signal strength: status and prospects, in JHEP, 11, 094-094.
The anomalous magnetic moment of the muon in the Standard Model
Aoyama T., others (2020), The anomalous magnetic moment of the muon in the Standard Model, in Phys. Rept., 887, 1-166.
β Decays as Sensitive Probes of Lepton Flavor Universality
Crivellin Andreas, Hoferichter Martin (2020), β Decays as Sensitive Probes of Lepton Flavor Universality, in Phys. Rev. Lett., 125(11), 111801-111801.
$b\to s\ell^+\ell^-$ transitions in two-Higgs-doublet models
Crivellin Andreas, Müller Dario, Wiegand Christoph (2019), $b\to s\ell^+\ell^-$ transitions in two-Higgs-doublet models, in JHEP, 06, 119-119.
Addendum to Impact of polarization observables and $B_c\to τ ν$ on new physics explanations of the $b\to c τ ν$ anomaly''
Blanke Monika, Crivellin Andreas, Kitahara Teppei, Moscati Marta, Nierste Ulrich, Nišandžić Ivan (2019), Addendum to Impact of polarization observables and $B_c\to τ ν$ on new physics explanations of the $b\to c τ ν$ anomaly'', in Phys.Rev.D, 035035.
Combined explanations of $(g-2)_μ$, $(g-2)_e$ and implications for a large muon EDM
Crivellin Andreas, Hoferichter M. (2019), Combined explanations of $(g-2)_μ$, $(g-2)_e$ and implications for a large muon EDM, in An Alpine LHC Physics Summit 2019, 29-34, Nuovo Cim., Pisa29-34.
Correlating tauonic $B$ decays with the neutron electric dipole moment via a scalar leptoquark
Crivellin Andreas, Saturnino Francesco (2019), Correlating tauonic $B$ decays with the neutron electric dipole moment via a scalar leptoquark, in Phys. Rev. D, 100(11), 115014-115014.
CP Violation in Higgs-Gauge Interactions: From Tabletop Experiments to the LHC
Cirigliano Vincenzo, Crivellin Andreas, Dekens Wouter, de Vries Jordy, Hoferichter Martin, Mereghetti Emanuele (2019), CP Violation in Higgs-Gauge Interactions: From Tabletop Experiments to the LHC, in Phys. Rev. Lett., 123(5), 051801-051801.
Emerging patterns of New Physics with and without Lepton Flavour Universal contributions
Algueró Marcel, Capdevila Bernat, Crivellin Andreas, Descotes-Genon Sébastien, Masjuan Pere, Matias Joaquim, Novoa Brunet Martín, Virto Javier (2019), Emerging patterns of New Physics with and without Lepton Flavour Universal contributions, in Eur. Phys. J. C, 79(8), 714-714.
Explaining the Flavor Anomalies with a Vector Leptoquark
Crivellin Andreas (2019), Explaining the Flavor Anomalies with a Vector Leptoquark, in 54th Rencontres de Moriond on QCD and High Energy Interactions, 85-90, ARISF, Trieste85-90.
Generic loop effects of new scalars and fermions in $b\to s\ell^+\ell^-$ and a vector-like $4^{\rm th}$ generation
Arnan Pere, Crivellin Andreas, Fedele Marco, Mescia Federico (2019), Generic loop effects of new scalars and fermions in $b\to s\ell^+\ell^-$ and a vector-like $4^{\rm th}$ generation, in JHEP, 06, 118-118.

Collaboration

Group / person Country
Types of collaboration
University of Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Exchange of personnel
Institute of Theoretical Physics, Chinese Academy of Sciences China (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
TU München Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Warsaw Poland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
KIT Karlsruhe Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Institute for Nuclear Theory, University of Washington United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
University of Barcelona and Universitat Autonoma (IFEA) Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
From the Planck Scale to the Electroweak Scale (PLANCK) Talk given at a conference Explaining the Flavour Anomalies 03.06.2019 Granada, Spain Crivellin Andreas;
MIAPP workshop: Beyond the Standard Model with Precision Flavour Experiments Talk given at a conference New physics models for the flavour anomalies 13.05.2019 Garching, Germany Crivellin Andreas;
Alps 2019: Fourth Alpine LHC Physics Summit Talk given at a conference The magnetic moments of muon and electron and implications for a large muon EDM 22.04.2019 Obergurl, Austria Crivellin Andreas;
Precision era in High Energy Physics Talk given at a conference b->sll in Two-Higgs-Doublet Models 07.04.2019 Portoroz, Slovenia Crivellin Andreas;
XILV Rencontres de Moriond QCD Talk given at a conference Explaining the Flavour Anomalies with the Pati-Salam Leptoquark 23.03.2019 La Thuile, Italy Crivellin Andreas;
Les Rencontres de Physique de la Vallee d’Aoste Talk given at a conference g-2 Anomalies 17.03.2019 La Thuile, Italy Crivellin Andreas;


Self-organised

Title Date Place
Heavy-Quark Physics and Fundamental Symmetries 12.08.2019 Seattle, United States of America

Awards

Title Year
Premio "Vito Volterra" 2020

Associated projects

Number Title Start Funding scheme
175449 Flavourphysik im Standardmodell und dessen Erweiterungen 01.11.2017 Project funding
154834 Flavour Physics beyond the Standard Model 01.01.2016 Ambizione

Abstract

The ultimate goal of particle physics is to uncover the fundamental constituents and interactions of matter. Currently, this is described by the Standard Model (SM) which has been tested extensively in the last decades and its last missing piece, the famous Higgs particle, was discovered at CERN in 2012. Now the focus of High Energy Physics is on the discovery of new particles and new laws of physics beyond the SM. In this way one hopes to answer great open questions, e.g. why our universe consists of matter and not antimatter or the origin and nature of Dark Matter.In addition to direct searches for new physics (NP) at the LHC searching for new resonances, precision experiments are searching for quantum effects of new particles. In this context flavour experiments are especially interesting: matter particles appear in three generations which differ by their flavour quantum number, i.e. while being otherwise identical, they differ in mass. All matter particles are grouped into three . Flavour physics studies the transitions between these three generations. In the SM the only source of flavour violation in the quark sector is the Cabibbo-Kobayashi-Maskawa (CKM) matrix while in the limit of vanishing neutrino masses, lepton flavour is exactly conserved and lepton flavour universality (LFU) violation originates only from tiny couplings of leptons to the Higgs. Therefore, flavour violation is highly suppressed in the SM and thus very sensitive to NP.For generic NP, flavour observables probe much higher energy scales than LHC searches and one can expect to find NP here, before discovering it directly in high energy collisions. In fact, while the LHC did not directly observe new particles so far, in the last years, several experiments accumulated very interesting indications for NP in semi-leptonic B meson (bound states involving a heavy bottom quark) decays. In b->c tau nu processes a combined deviation from the SM prediction of ~4 sigma has been observed and a global fit to b->s mu mu observables even prefers NP compared to the SM with a significance above the 5 sigma level. Furthermore, there is the long standing anomaly in the anomalous magnetic moment of the muon (a_mu) at the 3 sigma level. In my view, these measurements are the most compelling indication for a breakdown of the SM at high energies (disregarding neutrino masses and dark matter which can be accommodated in the SM context without significantly affecting collider observables) since its foundation over 40 years ago.The goal of this proposal is to study the implications of these intriguing hints for LFU violating NP in great detail. The model independent effective field theory approach, in which the SM is supplemented with higher dimensional operators, already uncovered possible patterns of NP contributions but has of course to be continuously updated with forthcoming experimental data. Concerning concrete models, leptoquarks (LQs), i.e. hypothetical new particles which couple quarks to leptons, provide a natural explanation of measured data in B and also for a_mu. Such LQs occur for example in Grand Unified Theories and a large part of this proposal is devoted to a comprehensive study of the effects of these particles. Models with Z' bosons will be examined in detail since they provide a valid explanation to the b->s mu mu anomalies, but alternative solutions will also be pursued. This research plan is thus divided into seven sub-projects: A) Leptoquarks, B) Z' models, C) Flavour in extended Pati-Salam models, D) Loop effects in b-> s mu mu and a_mu, E) Leptoquarks and Supersymmetry, F) alpha_s corrections to mu->e gamma, G) Review article: ``New Physics in the Flavour Sector''. By examining the intriguing hints for LFU violation using model building, precision calculations and phenomenological analysis, this project has the unique potential of uncovering the model of NP superseding the SM.
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