Flavour Physics in and beyond the Standard Model Andreas Crivellin Flavour Physics in and beyond the Standard Model Supported by a Marie Curie Intra-European Fellowship of the European Community's 7th Framework Programme under contract number (PIEF-GA-2012-326948).

“Missing Energy” Decays Let’s now discuss “missing energy decays” and the excitement in this area. Thanks to Tom Browder!

Outline: Introduction: The Standard Model of Particle Physics Particle content Interactions Flavour physics in the SM CKM Matrix Flavour changing neutral currents Hints for New Physics in flavor observables Implications for New Physics 3

What are the smallest building blocks of matter and which forces act between them? 4

Fundamental Matter Particles Electrons Quarks Neutrinos Super-Kamiokande Point-like

Forces Gauge Theory (local symmetry) Interaction particles Quantum field theory Interaction particles

Feynman diagrams Visualize Interactions in Quantum Field Theory Tree-level 1-loop

Quantum Electro Dynamics (QED) U(1) gauge theory Force Particle: Photon Tested to extreme precision E.g. anomalous magnetic moment of the muon calculated up to the 5-loop level (Kinoshita et al.) 2-loop Feynman diagrams for the anomalous magnetic moment

Quantum Chromo Dynamics (QCD) Charge: color (only for quarks) Force particle: gluon SU(3) → 8 gluons Asymptotic freedom Prediction meson and hadrons Essential for hadron colliders like the LHC Pertubative and non-perturbative effects in flavor physics

Gravitation (General Relativity) Force is curvature of space time How to quantize it? Graviton? Not part of the Standard Model (and this talk)

The weak force SU(2) gauge group acting only on left-handed fermions Charge: component of the SU(2) doublets Charged (W) and neutral (Z) currents Weak because the gauge bosons are massive

The Higgs Boson and Electroweak (EW) Symmetry Breaking One complex scalar doublet in the standard model (4 degrees of freedom) Three components give masses to Z and W Only one physical component remains: The Higgs particle Generates masses after EW symmetry breaking

The Higgs boson Couples to EW gauge bosons and fermions proportional to their masses Tree-level production in proton-proton collisions suppressed The first and only particle ever observed produced via quantum loop effects. Standard Model of particle physics in now complete

The Standard Model

New Physcis? The Standard Model works up to the 100 GeV scale (10-18 cm) But: Why are neutrinos nearly massless? Are fermions, the Higgs and the gauge bosons fundamental particles? Why is the electric charged quantized? What about gravitation? More CP violation to generate (anti) matter asymmetry? Hierarchy Problem: SUSY? Extra dimensions? Are there new heavy particles?

Flavour Physics in the SM 16

Light Mesons

Bottom Mesons

Yukawa Interactions and fermion masses Interactions of the Higgs particle with fermions The quarks acquire masses after electroweak symmetry breaking Diagonalized by biunitray transformations Only the charged W vertex is flavor changing

The CKM matrix CKM matrix The mass matrices are diagonalized by (bi) unitary transformations Neutral gauge interactions are proportional to the unit matrix etc. Only the W vertex is flavour changing in the SM. CKM matrix

Tree-level determination of the CKM elements Vub Vcb Vus Kaon decays

NP in CKM elements? Inclusive and exclusive determinations of the Vub and Vcb do not agree well. Right-handed W-b-u coupling? Update of AC, S. Pokorski, PRL (2014)  No new physics in CKM elements, i.e. SM problem

Magnitude of the CKM elements (tree-level) Vud from beta decay Vcd and Vcs from D decays Vtb, Vtd and Vts determined by CKM unitarity Vtb also from t→Wb but not competitive

Flavour Changing Neutral Current (FCNC) processes 24

FCNCs Absent in the SM at tree-level as all flavor violation comes from the CKM matrix in the charged the W-quark Involve small off-diagonal CKM elements Induced at the 1-loop level by quantum fluctuations suppressed by the large W mass Very suppressed in the SM Maybe large in theories beyond the SM Excellent place to search for heavy New Physics

ΔF=2 processes Particle anti-particle oscillations Mass difference CP violation Agree well with the SM within uncertainties Test NP up to 10,000 TeV

Global CKM Fit Indirect and direct determinations agree very well

B→Xsγ Inclusive decay Complete perturbative calculation Misiak et al. 1503.01789 SM and experiment agree very well Test of chirality changing new physics

Hints for New Physics in the Flavour Sector 29

B→K*µµ Semi-leptonic decay form factor dependence Clean observables are (approximately) free of hadronic uncertainties 27 2-3 σ deviation from the SM mostly in P5’

B→K*µµ Can be explained by a NP contribution to the operator New physics explanation is not easy (MSSM, 2HDM do not work). Most natural explanation: Neutral gauge boson (Z’) Leptoquarks Subleading hadronic effects might be larger than expected… Further supported by Bs→ϕμμ R. Horgan, Z. Liu, S. Meinel, and M. Wingate (2015), 1501.00367.  arXiv:1307.5683 28

R(K) = B→Kµµ/B→Kee Lepton flavour universality violation 2.6 σ deviation from the theoretically rather clean SM expectation Also lepton flavour violation? 29

Global fit to b→sμμ data Global analysis give a very good fit to data Symmetry based solutions give a very good fit to data: W. Altmannshofer, D. M. Straub, arXiv:1503.06199. T. Hurth, F. Mahmoudi, and S. Neshatpour, 1410.4545. Descotes-Genon et al. 1501.04239 30 Fit is 4-5 σ better than in the SM

Tauonic B decays Explained by a charged Higgs or leptoquarks Tree-level decays in the SM via W-boson Lepton flavor violation in the charged current Explained by a charged Higgs or leptoquarks 34

Extended Higgs sector at the EW scale CMS and ATLAS finds 2.6 σ difference from zero Lepton flavour violation Large branching ratio Extended Higgs sector at the EW scale 8

Explanations of the Flavour Anomalies Additional neutral gauge bosons (Z’) Extended Higgs sector Leptoquarks 5

Z’ models with gauged AC, G. D‘Ambrosio and J. Heeck Explaining B→K*μμ, R(K) and h→τμ in a two-Higgs-doublet model with gauged Lμ-Lτ arXiv:1501.00993, PRL 114 (2015) 151801 Adressing the LHC flavour anomalies with horizontal gauge symmetries Phys.Rev. D91 (2015) 7, 075006 37

B→K*µµ, R(K) Bs mixing allowed regions 38

and 39

LHC limits 40

Conclusions The CKM mechanism of flavor violation has been confirmed with high precision Flavor physics is an excellent testing ground for physics beyond the SM: It test NP indirectly via quantum fluctuations Complementary to direct LHC searches Deviations from the SM were observed in B and Higgs decays. Is lepton flavor (universality) violated? Extended Higgs sector? Leptoquarks? New gauge bosons? 41

Type X 2HDM with perturbations 42

2HDM of type X + corrections Allow for additional couplings The parameters describe flavor-changing neutral Higgs interactions which we assume to be of the form

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Branching ratio can even reach the percent level 46

No simultaneous explanation without fine-tuning 47