Flavour Opportunities at the Intensity Frontier

Transcription

1 Flavour Opportunities at the Intensity Frontier INFN, Rome Introduction Where we stand and where we are heading to in flavour physics Future scenarios & interplay with LHC Conclusions

2 INTRODUCTION The Standard Model works beautifully up to a few hundred GeV's, but it must be an effective theory valid up to a scale Λ Mplanck: EW scale Violates accidental symmetries Has accidental symmetries Page 2

3 INTRODUCTION - II Two accidental symmetries of the SM are crucial for our discussion: 1) Absence of tree-level flavour changing neutral currents, GIM suppression of the loop level 2) No CP tree level Flavour physics extremely sensitive to NP!! Page 3

4 EXPRESS REVIEW OF THE SM All flavour violation from charged current coupling: CKM matrix V 2 V CKM = A i 1 2 A 2 2 A 1 i A O Top quark exchange dominates FCNC loops: third row (Vtq) determines FCNC's Page 4

5 Flavour summarized on the plane BR(b ul ), BR(B l ) CC mq (Bq-Bq mass diff.) _ ACP(b ccs) (J/ K,...) ACP(b sss, dds) ( K, K,...) ACP(b ddd, uud) (, ) BR(b cud, cus) (DK,...) NC BR(B ) CC BR(B )/BR(B ) NC K NC K+ NC CC NC CC/NC CC Page 5

6 Where we stand: UTA & NP in F=2 Consider ratios of (SM+NP)/SM F=2 amplitudes Determine C's and 's using generalized UT analysis Derive bounds on NP scale and/or couplings Page 6

7 Our present knowledge: Page 7

8 SUMMARY OF CONSTRAINTS No deviation seen in K physics, slight tension in phase of Bd mixing, ample room for NP in phase of Bs mixing (might become solid evidence w. Tevatron & LHCb) Page 8

9 Ratio of NP/SM contributions is < 95% prob. in Bd mixing, and ~60% in Bs mixing (but compatible with zero at 2 ). Page 9

10 THE SCALE OF NP The constraints we obtained can be used to put lower bounds on the scale of NP models with a given flavour structure: ANP/ASM ~C/CSM Ki numeric coefficient of O(1), Fi flavour structure, L loop coefficient, NP scale Page 10

11 BOUNDS ON THE NP SCALE To be relevant for the hierarchy problem, NP must have a highly nontrivial flavour structure!! Page 11

12 Two broad flavour scenarios 1) Minimal Flavour Violation (i.e. no new source of flavour violation beyond Yukawa couplings) effectively holds at least at the level seen in K and Bd mixing, i.e. < 40%. 2) New sources of Flavour & CPV are at work in transitions between 2nd and 3rd families, but strongly suppressed elsewhere. Nonabelian flavour symmetries? Guts +? Tevatron and LHCb will tell us soon! Page 12

13 What we are aiming at Being able to determine the flavour structure of whatever NP seen at the LHC Being able to derive info on the full spectrum of NP if LHC only sees part of it Being able to cover indirectly the region of NP masses just above the LHC reach, pushing the indirect bound on as high as possible Page 13

14 How do we get there - I A few % error on CKM parameters in the generalized UTA; Determining NP contributions to F=2 and F=1 transitions in all sectors (K, Bd, Bs, D) at the few percent level; Improving Lepton Flavour Violation and Lepton Universality bounds by more than one order of magnitude Page 14

15 How do we get there - II CKM parameters in the presence of loopmediated NP: Vcb,ubincl,excl, (B DK) NP contributions to F=2 amplitudes: (b ccs), s(b ccs), D0 ASLd,s, ( )d,s Page 15

16 How do we get there - III NP contributions to F=1 amplitudes: b s: (B S S S S,...), Bs K*0K*0 (penguins), B K(*) (penguins & ewp), B Xs (ewp) B Xs (BR&ACP) (photon peng), B Xsll (BR&AFB) (photon & ewp), (B Ks ) (RH ops), Bs (scalar peng) b d: B (ewp) B Xd (ewp) B Xd (BR&ACP) (photon peng), B Xdll (BR&AFB) (photon & ewp), S(B ) (RH ops), Bd (scalar peng) s d: KL K+ (ewp) KL ll (photon & ewp) Page 16

17 How do we get there - IV LFV: e e (photon peng), ll ell eee, e (photon, ewp & boxes), e (photon, ewp, boxes & Higgs) Lepton Universality: K e K B B (Higgs) Charged current scalar interactions: B (Higgs) Page 17

18 Experimental... B (4S) Charm physics physics + FC physics (CPV,... ) K physics B (5S) K Page 18

19 ...and theoretical efforts needed! no theory improvements needed (J/ K), (DK),, lepton FV & UV, CPV in B->X, D and decays, zero of FB asymmetry B->Xsl+l- SM already known with the required accuracy improved lattice QCD meson mixing, B->D(*)l,B-> ( )l, B->K*, B->, B->l Bs-> target error: ~1-2% Feasible (see SuperB CDR) improved OPE+HQE B->Xu,cl target error: ~2-3% Feasible getting exp. rid of annihilation & shape function (see arxiv: ) improved QCDF or SCET or flavour symmetries or data driven methods S's from TD ACP in b -> s transitions target error: ~2-3% need either breakthrough in computing power corrections or data-driven approaches (Dalitz analyses particularly favourable) Page 19

20 FUTURE SCENARIOS AND COMPLEMENTARITY W. LHC Page 20

21 Let's begin with the worst case... Let's assume that LHC finds the Higgs and nothing else (including no deviation in Bs mixing). Were naturalness arguments wrong or is the Higgs sector just a bit fine-tuned? Flavour physics gives us the chance to reach for higher scales! Page 21

22 The basic step: CKM matrix at the % the dream _ KL -> π ν ν 0 error budget Generalized UT fits: today SuperB CKM at % in the 0.177± ±0.005 presence of NP! 0.360±0.031 ±0.005 Will detect deviations from the SM at the level of 3% in CBd and of 0.5 in Bd the nightmare U. Haisch, Kaon '07 Page 22

23 The NP reach we can obtain depends on the NP flavour structure: MFV small tan : won't go beyond the TeV region, although b s will cut a lot MFV large tan : can reach several TeV's with B l : MSSM 2HDMII SuperB CDR Page 23

24 The situation improves considerably if new sources of FV are present: can reach 3 evidence for gluino masses up to 10 TeV for maximal b-d squark mixing, and go beyond the TeV for Cabibbo-like mixings. SuperB CDR Page 24

25 The case of WED Warped extra dimensions/minimal composite Higgs could solve the hierarchy problem and explain SM flavour structure via fermion localization/degree of compositeness However they generate chirality-flipping contributions to F=2 amplitudes at tree level very strong constraints from K Page 25

26 Csaki et al. '08; Buras et al. '08; Agashe et al. '08 A moderately fine-tuned WED model should lie above the LHC reach, but should give visible effects in flavour physics at the few % level ( K, S(KS ),...). Page 26

27 A less pessimistic scenario... Let's assume that ATLAS and CMS see some good candidates for SUSY particles. We should try and reconstruct the whole SUSY Lagrangian, but probably we won't know the whole spectrum and most probably we won't be able to measure flavour couplings at high-pt Page 27

28 Reconstructing LSUSY (Some of the) Diagonal sfermion masses will be LHC; off-diagonal terms to be determined from flavour (relevant parameters: ( dij)ab= ( dij)ab/(mii)aa(mjj)bb) Page 28

29 SuperB CDR Reconstructing ( d13)ll=0.085 ei /4 and ( d23)lr=0.028 ei /4 for msusy=1tev Page 29

30 For a full reconstruction of the hadronic part of the SUSY Lagrangian, need % knowledge of meson mixings (including D) and FCNC decays Agreement with the SM as useful as disagreement If deviation from SM in Bs confirmed, effort in measuring b s decays mandatory ~ ~ mixing could Notice that a large b s invalidate standard LHC strategies to search for SUSY LHC Workshop, arxiv: Page 30

31 Lepton Flavour Violation For slepton masses in the LHC range LFV becomes extremely interesting! In SUSY-GUTs: can identify the neutrino Yukawa flavour structure (CKM or PMNS) by studying & ; interesting correlations with b s transitions Interesting correlations also in MFV case: LFV from CKM LFV from PMNS Isidori, 4th SuperB workshop Page 31

32 LFV in an SO(10) SUSY-GUT Calibbi et al. 06 li ljll and li ljp useful to constrain Higgs and box contributions Page 32

33 OVERALL SUSY ASSESSMENT Combining high-pt and flavour data we can constrain LSUSY and thus get hints on: the SUSY-breaking mediation mechanism the flavour breaking mechanism the underlying presence of a GUT structure the origin of neutrino mixing p Okada et al. '07 large deviation expected detectable deviation possible Page 33

34 An optimistic scenario... Let's assume extra dimensions are seen at the LHC For warped extra dimensions this implies some mechanism to suppress tree-level contribution to K Fitzpatrick et al '07; Cacciapaglia et al. '07; Santiago '08; Csaki et al. '08; Improved precision on flavour physics necessary to establish flavour structure and identify suppression mechanism Page 34

35 The nonperturbative scenario... Let's assume there is no Higgs and nothing else to unitarize WW scattering at 1 TeV Perturbative unitarity of weak interactions is lost: electroweak chiral Lagrangian, Technicolour and all that... Not calculable or, when calculable, incompatible with electroweak data Barbieri '08 Not much can be said except that great fun would be guaranteed in all sectors! Page 35

36 CONCLUSIONS: PRESENT Present status: control CKM + NP F=2 at the 20-30% level, except for Bs mixing where O(1) NP is favoured Bounds on NP scale tell us that NP can be within the LHC reach only if it is MFV-like within at most 40% or it contributes O(1) to b s and <40% elsewhere Page 36

37 CONCLUSIONS: FUTURE Control CKM + NP in F=1,2 at the % level; push down searches for LFV by two orders of magnitude or lower; improve tests of LU Ensure determination of flavour structure of whatever NP seen at the LHC Ensure sensitivity to moderately finetuned NP above the LHC reach Requires covering the full spectrum of B(s), D, K and LFV observables Page 37

38 BACKUP SLIDES Page 38

39 - lattice QCD can reach the O(1%) precision goal in time - extrapolation assuming no improvement in algorithms, just increase in computing power V. Lubicz, 4th SuperB Workshop and SuperB CDR Page 39

40 The importance of gathering 75 ab-1 Page 40

41 Okada et al '07 Page 41

42 Okada et al '07 Page 42

43 Okada et al '07 Page 43

44 Okada et al '07 Page 44

45 F. FPCP08 Page 45

46 F. FPCP08 Page 46

47 Proceedings of Superb VI, arxiv: Page 47

48 Proceedings of Superb VI, arxiv: Page 48

49 Results for a typical flavour configuration with sizable mixings and splittings. _ Many _ experimental ~ ~ ~ ~+ ~ strategies affected: e.g. g->bbj->bb k, t-> 1b Page 49