Chaehyun Yu. in collaboration with P. Ko (KIAS) and Yuji Omura (Nagoya University) The 16 th LHC Physics Monthly Meeting, KIAS, Korea, Jun 01,

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1 Top FCNC Chaehyun Yu (Academia Sinica) in collaboration with P. Ko (KIAS) and Yuji Omura (Nagoya University) The 16 th LHC Physics Monthly Meeting, KIAS, Korea, Jun 01,

2 Flavor changing neutral currents In the SM, FCNCs are absent at the tree level Loop suppressed CKM suppressed GIM supressed FCNCs are good probe of new physics. FCNCs for bound states K K, B B, B B, D D mixing s s Which processes are proper for the test of the top FCNC? top decay same sign top singlet top production t+j resonance 2

3 Top FCNC Snowmass, arxiv: FCNC in the SM cannot be observed at the LHC - Top quark at LHC run II & III: 517 pb3000 fb ~ Any measurement on top FCNC implies the existence of new physics many models introduces tree-level top FCNCs Experimental anomalies might require large top FCNCs 3

4 Top FCNC search results Goldouzian, TOP2014 4

5 FCNH coupling pp thj Wu, arxiv:

6 Top FCNC top decay same sign top singlet top production t+j resonance m X mt any mx any mx mx mt less BG, but small xsec large xsec, but large BG FCNCs change the total cross section for top pair production Ds/s 1.96 TeV 8 TeV 13 TeV Y tu = % -0.3% -0.1% Y tu =1-27% -3.8% -2.5% 6

7 FCNCs can be mediated not only by one particle but also several particles 7

8 Top decay CMS bound CMS bound t hq t Xu( X a, H, Z) h WW, ZZ,, assume Y tu or g=0.1 g =0 Y Y tu tc y but, depends on the decay channel of X 8

9 Same sign top production constructive interference u u t ~ ~ h H t u u t t destructive interference u u t ~ ~ i h a t u u t t 9

10 Same sign top production Y Y Y g h h a tu tu tu H 10

11 Same sign top production Y Y Y g 2 h3 a1 0.1 h tu tu tu H 11

12 thj production pp thj p jet t 100 GeV the same cross section for the thj production, but different for the same sign pair production 12

13 How can we make top special? 13

14 Top 2HDM Z 2 symmetry,,, : 1 lr dr u R 1, 2,,, 3 : 2 LL QL ur The top quark is naturally heavy due to a large VEV of f 2 Flavor changing neutral Higgs couplings U(1) extension ï Flavor-dependent chiral U(1) model (Ko,Omura,Yu) 14

15 Flavor-dependent U(1) model Charge assignment : SM fermions Ko,Omura,Yu, JHEP1201,147 Left-handed quarks and righthanded down-type quarks have universal couplings. Flavor-dependent Higgs H cannot generate mass terms for right-handed up-type quarks 15

16 Flavor-dependent U(1) model Charge assignment : Higgs fields Ko,Omura,Yu, JHEP1201,147 introduce three Higgs doublets charged under U(1) in addition to H uncharged under U(1). The U(1) is spontaneously broken by U(1) charged complex scalar Φ. 16

17 Anomaly Cancelation Anomaly cancelation requires extra fermions: SU(2) doublets one extra generation vector-like pairs a candidate for CDM 17

18 Flavor-dependent U(1) model 2 Higgs doublet model : ( u1, u2, u3) (0,0,1) the fermion mass 18

19 Flavor-dependent U(1) model Gauge coupling in the flavor eigenstates - The 3 X 3 coupling matrix is defined by biunitary matrix diagonalizing the up-type quark mass matrix Gauge coupling in the mass eigenstates - Z interacts only with the right-handed up-type quarks ~0 or d flavor off-diagonal ij ~0 or d ij couplings 19

20 B physics Charged Higgs contributes to B physics. Neutral (pseudo)scalar ( a) ( a) ( a) Yuu Yuc Yut ur ( a) ( a) ( a) ( ul cl tl ) Ycu Ycc Yct cr h ( ia ) ( a) ( a) ( a) Ytu Ytc Y tt t R Top mass enhance Top FCNC strong relation Y V Y u * au ij 2( CKM ) li lj Charged Higgs sector Ydu Ydc Ydt ur ( d L s L b L) Y su Y sc Y st c R h Ybu Ybc Y bt t R B (*) B D b s in one loop 20

21 B (*) D B (*) D * RD ( ) RD ( ) BABAR SM BABAR, Fajfer,Kamenik,Nisandzic, Mescia combined

22 * R ( D ) and R ( D ) in 2HDM (type-ii) BABAR 2HDM b q h c q mm b tan m 2 2 H Allowed regions: tan / m fo r RD ( ) H tan / m for H *.04 RD ( ) SM BABAR, * Combination of RD ( ) and RD ( ) excludes full parameter space with 99.8% probability. 22

23 R(D (*) ) at Belle Kuhr, FPCP2015 consistent with the SM and BABAR both results are larger than SM predictions 23

24 R(D (*) ) at Belle Kuhr, FPCP2015 consistent with type-ii 2HDM at 2 tan / m H

25 R(D * ) at LHCb Ciezarek, FPCP2015 Agreement with the SM at 2.1s level In good agreement with the Belle and BABAR results 25

26 average Ligeti, FPCP2015 RD ( ) RD ( ) RD ( ) 1. 8 RD BABAR * ( ) BABAR 2.7 RD BELLE * ( ) BELLE 1.0 RD tot 8 ( *. tot ) 32 * (*) LHCb R( D ) 2.1 R( D ) 3 7 tot. 26

27 B b q BR( B ) (*) B D B W, h b W, h c (*) B D q u (b,c) coupling (b,u) coupling Y.Horii, Tau

28 Effective Hamiltonian Effective Hamiltonian Charged Higgs 28

29 Wilson coefficients Flavor-independent New terms in flavor-dependent U(1) model diagonalization matrix g R : the same as the type-ii 2HDM. : generate non-mfv interactions. 29

30 2HDM The BABAR discrepancies require large charged Higgs contribution B tn requires small (t,u) coupling, 30

31 Same sign top production in 2HDM tqh tqa 31

32 Summary FCNCs are good probe of new physics. There are several top FCNC observables, and they are complementary to each other. A few particles which have FCNC couplings can exist in the model and their effects may be interfered constructively or destructively. BTD(*)tn anomaly may be resolved by flavor-dependent U(1) model, but it predicts large FCNCs. In particular, a lot of parameter spaces may be tested by the same sign top pair production at LHC run 2. 32

33 R(D (*) ) at Belle (non-official) From A. Bozek s slide at FPCP

34 Mono-top Andrea,Fuks,Maltoni,,, arxiv: CMS, arxiv:

35 Top FCNC search results Br( t Zq) 0.05% Br( t hq) 0.56%(0.79%) at 95% C.L. Goldouzian, TOP

36 ppt X Single top production p jet t 100 GeV 36

37 Chiral U(1) model 3 Higgs doublet model: ( u1, u2, u3) ( q,0, q) 37

38 2HDM Large C L with C R =0 could explain data. Large C R is not capable of achieving i R(D (*) ) without t sizable C L. Type-II 2HDM (or 2HDM III with MFV) generate only C R. could not explain R(D (*) ) at BABAR. RD ( ) * RD ( ) Crivellin,Greub,Kokulu,

39 3HDM 2 pairs of charged Higgs + 2 CP-odd pseudoscalars. parameter spaces are large not difficult to find the allowed region without fine-tuning. ex) degenerate case m 1 h 2 h m 39

40 Wilson coefficients Type-II 2HDM ~ 0 only C R has sizable contribution. 40

41 ppt X Single top production p jet t 100 GeV 41