WG4 (Flavour) Summary

Transcription

1 WG4 (Flavour) Summary Vladimir V. Gligorov, CNRS/LPNHE HL-LHC Workshop, CERN,

2 Why flavour physics? I first used this slide around 9 years ago, wasn t original then and is still relevant now 2

3 Theory & models Spectroscopy & QCD Rare processes & BSM CKM metrology The pillars of flavour physics 3

4 WG structure & business Twiki : Productive joint sessions with both BSM and SM WGs, allow links to HE-LHC studies most WG activity on HL-LHC side. Global reminder of lumi assumptions for HL-LHC : 3000fb -1 for ATLAS/CMS, 300 fb -1 for LHCb Upgrade II. WG report outline in place & people have been tasked with filling the sections, end of July as a deadline for the 0 th drafts. A big thank you to all our speakers this week, my co-conveners, and apologies to everyone whose material was not used! 4

5 Theory & models Spectroscopy & QCD Rare processes & BSM CKM metrology CKM metrology 5

6 The endurance of CKM metrology Test consistency of SM picture of quark mixing, breakdown in consistency indicates NP

7 CKM metrology today Entering the precision regime, SM picture solid but still room for O(10%) NP effects!

8 CKM metrology gives hard constraints RK* Δm s constraint! Model prefers An example from Hiller & Nišandžić (arxiv ) but applies generally

9 dels and CKM! The absence of FCNC already now sets strong constraints on the multi TeV-scale Fig. 1. Leading order diagrams for neutral meson mixing in the SM. predictions (a) physics (higher than those found in direct searches so far, even foreseeable at LHC)! metrology gives hard constraints Beauty mixing phenomenology in a nutshell grams of the SM processes contributing to Bs0! µ+ µ decays, involving top quarks and W bosons: Z0 rams on the left and box diagram on the right. Self energy (gluonic) corrections and contributions Excellent pedagogical introductions to Higgs neutral meson onsidered. 4 5,6 7,8 mixing can be found in auge symmetry, as we expect from general arguments, textbooks, recent reviews and lecture notes. An up-to-date review of exper9 imental constraintsin onthe B meson mixing cangeneral also be found in the PDG. The folplitudes can be written following form y calculate a decay rate, one needs to account for the fact that quarks are conlowing discussion applies to neutral mesons of any kind. However, we shall denote e hadrons, bound by the exchange of soft gluons. The case of the B 0( )! µ+ µ the flavour eigenstate with the symbol B for beauty meson and use numerical he cleanest possible exclusive B-decay: due to the0 purely leptonic final state, all 0 c c that apply to Bs and NP d. rbative effects cansm be estimates confined to a single parameter, the B B-meson decay constant, = A +, (3.1) 0 2 a the axial-vector current matrix element [28]: 2 MW 0 0 arxiv: ! 0 s d 2.1. Time-evolution of the B -B system µ g5 b Bq ( p) = ipµ FBq, 0 qg 0 (11) of freedom. This structure is completely general: the KM factors and eventually a 1/(16 ) suppression if ance about the c, the values of the scale probed by ecay amplitude a meson Mresult i (e.g. K, D, B)Eq. into a (3.1) final stateallows F i (e.g. pp, µµ), wever, theforgeneral in us to predict Since the meson decays and we do not consider the wave function of final states, the y 1/4 G is not hermitian. periments: the sensitivity on scale as N where Hamiltonian H However, like any other, complex matrix, it can be A( M! F ) = h F H Mi = p  C (µ) h F Q (µ) Mi. (13) 2 decomposed in terms of two hermitian matrices, which we label by M and, observable. This implies that is not easy to increase i This technique has been since a long time in particle physics with great success!3" H = Mused (3) 2. searches only. Moreover, from Eq. (3.1) it is also clear Since M and are hermitian, their diagonal elements are real and we have M21 = above the TeV where (csm Mc11NP= ),M22namely M12for and models = T invariance requires and 11 = 22. Ignoring CP 4 for the moment the interference with phases in the final state, the common phase 0 0 the symmetry-breaking pattern of the SM. of B and B is arbitrary such we can choose either the phase of M12 or 12 and their phase di erence matters. Consequently, the mixing can be parametrized A been moreshown general (and older) erators haveonly already in Table 1.1. Asway can of seeing the same thing by five real parameters, which are conventionally chosen to be Consider the wave function B (t) for a neutral meson that is the superposition of 0 s the four-momentum of the initial B-meson 0and q represents the d or s quark. flavour eigenstates B and B. The time-evolution of its projections into flavour ical calculations of hadronic decay rates are based on effective Hamiltonians of 2 eigenstates is given by a Schr odinger equation 9]:!! 0 0 GF i hb H11 H12 (12)hB B(t)i Heff = p  C (µd) Qi (µ ), B(t)i NP2 i i =. (2) 0 0 H H dt hb B(t)i hb B(t)i eff F i i i

10 CKM metrology with HL-LHC SM desert NP dream Understanding the flavour structure of quark mixing is critical whether NP is found or not

11 CKM metrology with HL-LHC With HL-LHC statistics can make precision determinations of UT apex with subsets of observables => powerful test of CKM consistency and check against systematic effects!

12 Interpreting at tree level CKM angle gamma still solid forever, other tree-level observables require more work!

13 Interpreting at loop level Penguin effects need work but should be controllable throughout HL-LHC period. Important that lattice is able to keep up with Δm s and Δm d for precision interpretation!

14 Key measurement : CKM angle γ LHCb s HL-LHC precision on γ will dominate world average. Unique opportunity to measure either γ or φs at 1 level using D s K, only pure tree-level measurement of φ s!

15 Key measurement : φ s With HL-LHC stats LHCb has at least 5 independent ways of resolving the SM φ s CMS L1 track trigger hugely exciting! If B s φφ is possible why not B s φγ? ATLAS & CMS projections for φ s are being worked on for the yellow report chapter

16 HL-LHC

17 HL-LHC Charm theory is notoriously difficult A Lenz If you want an easy life go sell internet ads V V Gligorov HL-LHC is a potentially unique opportunity to probe charm CPV and mixing at the 10-5 level, will require a lot of work and progress on the theory side to interpret it properly!

18 HL-LHC Many other observables also available, opportunities abound also in rare charm decays

19 Unique opportunities in metrology LHC experiments may be able to resolve SM ΔΓ d LHCb in a unique position to precisely map out CPV in baryonic decays for the first time, as well as making unprecedented studies in B c sector.

20 Theory & models Spectroscopy & QCD Rare processes & BSM CKM metrology Rare processes & BSM 20

21 Anomalies here, anomalies there

22 HL-LHC with muons ATLAS and CMS studies for K * μμ are ongoing for HL-LHC

23 HL-LHC with electrons What can ATLAS and CMS do for K * ee?

24 Connection to B s μμ Naively : probes C10. But additional observables become available with HL-LHC stats!

25 B s μμ at CMS Probably can t harmonize systematics but should discuss combination qualitatively

26 B s μμ at ATLAS & combination Big job done in last months to concretize alternative trigger strategies!

27 NP scale HL-LHC

28 From discovery to interpretation Angular observables and interplay between different R measurements very important

29 Angular observables in upgrade II

30 Connection to high-p T searches

31 Connection to high-p T searches

32 Connection to LFV (i.e. τ 3μ) searches O(10-9 )

33 Strange rare decays LHC production & LHCb geometry give great reach for strange physics if trigger works!

34 Strange observables unique to HL-LHC

35 Theory & models Spectroscopy & QCD Rare processes & BSM CKM metrology Spectroscopy & QCD 35

36 LHC is a unique tool for spectroscopy

37 Illustration of the power of HL-LHC From discovery to precise characterization of exotic hadrons!

38 How heavy can HL-LHC let us probe?

39 DAQ is the critical experimental point Rate (MHz) Partially reconstructed signals BEAUTY CHARM STRANGE (τ > 0.2 ps) (circa 2032) econstructible) signal rates as a function of Every bunch crossing contains signal relevant to spectroscopy : real-time analysis only way

40 Theory & models Spectroscopy & QCD Rare processes & BSM CKM metrology Theory & models & conclusions 40

41 HL-LHC : discovery understanding HL-LHC datasets give numerous complementary observables which are not theoretically limited. This is true in both CKM metrology and in the study of rare decays and processes. Global interpretation allows characterization of any observed NP! Connects to and can guide direct high-p T searches. Crucial to continue exploring not only beauty but also baryonic, charm, and strange sectors, complementary information and unique opportunities.

42 LHC

43 Backups 43

44 NP model predictions in Kaon physics As in other areas, complementary observables very important

45 From measurement to interpetation