Matter, antimatter, colour and flavour in particle physics

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1 Matter, antimatter, colour and flavour in particle physics Sébastien Descotes-Genon Laboratoire de Physique Théorique CNRS & Univ. Paris-Sud, Université Paris-Saclay, Orsay, France RBI, Zagreb, 5 Feb 2016 LPT Orsay Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 1

2 Particle physics Probing matter at smaller and smaller distances = higher and higher E Subatomic regime: relativistic and quantum effects are important Energy collision does not break matter in smaller pieces... but is converted into new (pairs of) particles and antiparticles Prob(particle production or decay) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 2

3 H Hi ggs The Standard Model Fermions (spin 1/2) : constituents 1st generation: ordinary matter 2 other copies: 2nd and 3rd generations same interactions, but more massive, instable and decaying quickly into the first 3génér at i ons several flavours of quarks (u, d, s...) and leptons Bosons (spin 1) : interactions electromagnetic, strong, weak interactions due to the exchange of gauge bosons (photon, gluons, W and Z ) Se bastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 3

4 H Hi ggs The Standard Model Fermions (spin 1/2) : constituents 1st generation: ordinary matter 2 other copies: 2nd and 3rd generations same interactions, but more massive, instable and decaying quickly into the first 3génér at i ons several flavours of quarks (u, d, s...) and leptons Bosons (spin 1) : interactions electromagnetic, strong, weak interactions due to the exchange of gauge bosons (photon, gluons, W and Z ) electromagnetic interaction binds electrons and nuclei into atoms strong interaction binds coloured quarks into composite hadrons weak interaction triggers heavy quark decays into lighter quarks Se bastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 3

5 H boson Standard Model well tested in colliders (LEP, SLAC, KEK, Tevatron, LHC... ) 2012: discovery of scalar particle, corresponding to the H boson needed for consistent description of electromag and weak interactions Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 4

6 H boson Standard Model well tested in colliders (LEP, SLAC, KEK, Tevatron, LHC... ) 2012: discovery of scalar particle, corresponding to the H boson needed for consistent description of electromag and weak interactions Interaction of H boson with fermions (Yukawa interactions) related to the description of masses for the fermions the stronger the coupling, the heavier the mass leads to particle-antiparticle asymmetry in weak interactions CP asymmetry, constrained by quark decays Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 4

7 An accurate description of flavour m v V κ V or m v F κ F ATLAS Preliminary 1 s = 7 TeV, fb 1 s = 8 TeV, 20.3 fb Observed SM Expected W Z t excluded area has CL > 0.95 sin 2β ε K α γ excluded at CL > 0.95 & m s m d m d µ τ b η α V ub CKM f i t t e r EPS 15 τ ν γ V ub Λ b γ V ub SL β α ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) Particle mass [GeV] H couplings proportional to masses CP asymmetry in CKM matrix parametrised by ρ, η ρ Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 5

8 An accurate description of flavour m v V κ V or m v F κ F ATLAS Preliminary 1 s = 7 TeV, fb 1 s = 8 TeV, 20.3 fb Observed SM Expected W Z t excluded area has CL > 0.95 sin 2β ε K α γ excluded at CL > 0.95 & m s m d m d µ τ b η α V ub CKM f i t t e r EPS 15 τ ν γ V ub Λ b γ V ub SL β α ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) Particle mass [GeV] H couplings proportional to masses CP asymmetry in CKM matrix parametrised by ρ, η Many SM parameters linked to its flavour structure, i.e. fermions with different couplings to H (fermion masses, 9 parameters if m ν = 0) different couplings to W (CP asymmetry, 4 parameters) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 5 ρ

9 What next? γg ν i eud μ s c τ b W Z φ t NP? Gauge Higgs Fermions Standard Model a good description, but a real explanation? 19 parameters (for m ν = 0), 3 generations, 3 separate interactions particle-antiparticle asymmetry too small for cosmology low-energy effective theory of a larger more fundamental theory leading to New Physics (NP) waiting for us to be discovered? Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 6

10 What next? γg W Z φ Gauge Higgs ν i eud μ s c τ b t NP? Fermions Standard Model a good description, but a real explanation? 19 parameters (for m ν = 0), 3 generations, 3 separate interactions particle-antiparticle asymmetry too small for cosmology low-energy effective theory of a larger more fundamental theory leading to New Physics (NP) waiting for us to be discovered? Two ways of exploring NP Open the box: High energies (ATLAS, CMS) directly generate new particles at high E probe H couplings including self-couplings (scalar potential) Shake the box: High intensity (LHCb, Belle-II, NA62... ) rare processes involving lighter fermions quantum sensitivity to probe higher scales as intermediate states Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 6

11 Flavour-Changing Currents Flavour-Changing Charged currents: weak decays at tree level dominated by SM (W exchange) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 7

12 Flavour-Changing Currents Flavour-Changing Charged currents: weak decays at tree level dominated by SM (W exchange) Flavour-Changing Neutral Currents: forbidden in SM at tree level so good place for NP to show up (tree or loops) F = 2: B s mixing b u,c,t s F = 1: B s µµ W W s b u,c,t u,c,t b s H W s u,c,t b Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 7

13 Different processes for different goals SM NP SM NP SM NP SM expected to be dominant (tree-dominated processes) Metrology of SM SM and NP competing (loop-dominated processes) Constraints on NP SM zero or very small (SM symmetry forbidden proc.) Smoking guns of NP Separation between the last two categories hinge on theorists beliefs concerning the size of NP, theoretical accuracy of SM prediction and experimental measurements... Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 8

14 The good, the bad, the ugly At low energies, point-like interaction (like Fermi theory) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 9

15 The good, the bad, the ugly At low energies, point-like interaction (like Fermi theory) L = L SM + d 5 c n O(d) Λd 4 n NP operators O n suppr. by Λ mass scale of new particles Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 9

16 The good, the bad, the ugly At low energies, point-like interaction (like Fermi theory) L = L SM + d 5 c n O(d) Λd 4 n NP operators O n suppr. by Λ mass scale of new particles The good sensitivity to higher scales through low-energy processes interaction structure (spin-0 or spin-1, parity, charge conj... ) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 9

17 The good, the bad, the ugly At low energies, point-like interaction (like Fermi theory) L = L SM + d 5 c n O(d) Λd 4 n NP operators O n suppr. by Λ mass scale of new particles The good sensitivity to higher scales through low-energy processes interaction structure (spin-0 or spin-1, parity, charge conj... ) The bad Only indirect evidence, to be interpreted in models Mixture of information on couplings c n and mass scale Λ Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 9

18 The good, the bad, the ugly At low energies, point-like interaction (like Fermi theory) L = L SM + d 5 c n O(d) Λd 4 n NP operators O n suppr. by Λ mass scale of new particles The good sensitivity to higher scales through low-energy processes interaction structure (spin-0 or spin-1, parity, charge conj... ) The bad Only indirect evidence, to be interpreted in models Mixture of information on couplings c n and mass scale Λ The ugly Theory in terms of quarks, experiment in terms of hadrons Strong interaction not treated via perturbation theory α s 1 Various analytical and numerical methods : hadronic uncertainties Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 9

19 b sll (l = e, µ) Large set of potential channels (hadron spin, mass), depending on how quarks are dressed into hadrons (source of hadronic unc.) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 10

20 b sll (l = e, µ) Large set of potential channels (hadron spin, mass), depending on how quarks are dressed into hadrons (source of hadronic unc.) Analysed in a model-independent effective theory separating short distances (weak + NP) and long distances (strong) 10 H VtsV tb C i Q i +... i=1 Q 7 b sγ [real or soft γ emission] Q 9 b sll [via Z /hard γ] Q 10 b sll [via Z only] Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 10

21 b sll (l = e, µ) Large set of potential channels (hadron spin, mass), depending on how quarks are dressed into hadrons (source of hadronic unc.) Analysed in a model-independent effective theory separating short distances (weak + NP) and long distances (strong) 10 H VtsV tb C i Q i +... i=1 Q 7 b sγ [real or soft γ emission] Q 9 b sll [via Z /hard γ] Q 10 b sll [via Z only] NP adds to short-distance C i, enhancing new operators Q i? Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 10

22 B s µµ 80 CKM f i t t e r Summer 14 p value ] µµ) [10 Br(B d NNLO NLO Br(B µµ) [10 ] s 0.0 LHCb+CMS: Br(B s µµ) = ( ) 10 9 SM C 10, but also to NP (scalar and/or right-handed interactions) Br(B s µµ) in very good agreement with SM Br(B d µµ) not observed with enough significance (yet), but interesting to see how it will evolve in the future Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 11

23 B K µµ (1) K µ l µ + B 0 K db(b->k*μμ)/ds x 10 (GeV ) γ pole Large recoil Charmonia Low recoil 2 s (GeV ) 12 angular coeffs I i for kinematics of B K ( K π)µ + µ depending on 8 ampl. describing polarisation of final particles kinematic regimes according to s, energy carried by µ + µ significant hadronic uncertainties from strong interactions (form factors, describing the binding of quarks into hadrons) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 12

24 B K µµ (2) hierarchy of scales Λ QCD m b separating soft/hard strong inter. allowing one to disentangle soft and hard strong effects and to define observables P i with reduced hadronic uncertainties Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 13

25 B K µµ (2) hierarchy of scales Λ QCD m b separating soft/hard strong inter. allowing one to disentangle soft and hard strong effects and to define observables P i with reduced hadronic uncertainties P P q GeV q GeV Measured at LHCb with 1 fb 1 (2013) and 3 fb 1 (2015) Discrepancies for some (but not all) observables Two bins for P 5 deviating from SM by 2.9 σ each Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 13

26 B K µµ ] db/dq 2-7 c 4 /GeV 2 [10 Theory LHCb Binned theory LHCb Simpler kinematics: only branching ratio brings information Br(B K µµ) too low compared to SM q 2 [GeV /c 4 ] Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 14

27 B K µµ ] db/dq 2-7 c 4 /GeV 2 [10 Theory Binned theory LHCb 0.6 LHCb q 2 [GeV /c 4 ] Simpler kinematics: only branching ratio brings information Br(B K µµ) too low compared to SM R K = Br(B K µµ) Br(B Kee) = [1,6] ± equals to 1 in SM (universality of lepton coupling) deviation cannot be mimicked by a hadronic effect would require NP coupling differently to µ and e Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 14

28 One coefficient to rule them all Determine C i = Ci SM + Ci NP for b sµ + µ (assume no NP in b se + e ) χ 2 fit with B K µµ, B + K + µµ, B 0 K 0 µµ, B X s γ, B X s µµ, B s µµ, B K γ Large NP in C 9 ( 1/4 SM) favoured by all SM deviations P5' SM charm C 9 NP 1.1 C NP 9 C NP Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 15

29 One coefficient to rule them all Determine C i = Ci SM + Ci NP for b sµ + µ (assume no NP in b se + e ) χ 2 fit with B K µµ, B + K + µµ, B 0 K 0 µµ, B X s γ, B X s µµ, B s µµ, B K γ Large NP in C 9 ( 1/4 SM) favoured by all SM deviations P5' SM charm C 9 NP 1.1 C NP 9 C NP Coefficient Best fit 3σ conf. interval Pull SM p-value (%) SM 16.0 C7 NP 0.02 [ 0.07, 0.04] C9 NP 1.11 [ 1.71, 0.40] C10 NP 0.58 [ 0.11, 1.41] C9 NP = C10 NP 0.69 [ 1.27, 0.18] C9 NP = C9 NP 1.09 [ 1.62, 0.42] Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 15

30 Interpretations SM explanations seem contrived hadronic effects (for B K µµ, B s φµµ) statistical fluctuation (for R K ) bad luck (C 9 can accomodate all discrepancies by chance) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 16

31 Interpretations SM explanations seem contrived hadronic effects (for B K µµ, B s φµµ) statistical fluctuation (for R K ) bad luck (C 9 can accomodate all discrepancies by chance) NP models quite successful Z boson (additional interaction?) Parial compositeness (mixing between known and extra quarks) Leptoquarks (particles able to decay into a quark and a lepton) with new particles of masses of a few hundred GeV to a few TeV and specific patterns of couplings with fermions (b, s) and leptons (µ, e) Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 16

32 Outlook Flavour physics Powerful test of the Standard Model (H dynamics, masses, matter-antimatter asymmetry) Low-energy window on physics at much higher scale through quantum effects Powerful probe of New Physics beyond the SM But strong interaction difficult to tame! b sll decays Interesting patterns of deviation from SM in LHCb data Model-independent analysis favour short-distance contrib to C 9 No simple SM explanation, but various NP model explanation Waiting for confirmation with the Run-II results for LHCb, but also CMS, ATLAS (as well as for Belle-II and NA62)! Sébastien Descotes-Genon (LPT-Orsay) Matter, antimatter, colours and flavours 5/2/16 17

b sll 2015 and New Physics

b sll 2015 and New Physics b sll 15 and New Physics much ado about... something? Sébastien Descotes-Genon Laboratoire de Physique Théorique CNRS & Université Paris-Sud, 9145 Orsay, France in collaboration with L.Hofer, J. Matias,