Higgs Top couplings. Zhen Liu. Based on work with Ian Low and Lian-Tao Wang, to appear

Transcription

1 Higgs Top couplings Zhen Liu Based on work with Ian Low and Lian-Tao Wang, to appear

2 Key to many Puzzles Higgs boson discovery substantiates (more) many big questions in nature. It could well be the key to unlock some of nature s secrets. All connections could be revealed in Higgs measurements. Electroweak baryogenesis Hierarchy (Naturalness) Higgs Dark Matter Neutrino mass

3 Key to many Puzzles Higgs boson discovery substantiates (more) many big questions in nature. It could well be the key to unlock some of nature s secrets. Top quark plays special roles in Higgs physics All connections could be revealed in Higgs measurements.

4 Top quark and Higgs EFT Overview Top-quark and Higgs couplings are the key driver of the hierarchy problem (and subsequent naturalness problem). Solutions to such problem are likely to induce corrections to these couplings. Important to consider the CEPC sensitivity to Higgs and top EFT, even though the operational energy is below ttbar+higgs threshold.

5 Top quark and Higgs EFT Overview Top-quark and Higgs couplings are the key driver of the hierarchy problem (and subsequent naturalness problem). Solutions to such problem are likely to induce corrections to these couplings. Important to consider the CEPC sensitivity to Higgs and top EFT, even though the operational energy is below ttbar+higgs threshold. Here we choose a (minimal-)complete set of relevant operators, can be obtain by integrating out heavy particles and EOM. J. Aguilar-Saavedra, arxiv: , arxiv: C. Degrande, J. Gerard, C. Grojean, F. Maltoni, and G. Servant arxiv: , B. A. Kniehl and O. L. Veretin arxiv: , A. Hayreter and G. Valencia arxiv:

6 Top quark and Higgs EFT Overview Top-quark and Higgs couplings are the key driver of the hierarchy problem (and subsequent naturalness problem). Solutions to such problem are likely to induce corrections to these couplings. Here we choose a (minimal-)complete set of relevant operators, can be obtain by integrating out heavy particles and EOM. J. Aguilar-Saavedra, arxiv: , arxiv: C. Degrande, J. Gerard, C. Grojean, F. Maltoni, and G. Servant arxiv: , B. A. Kniehl and O. L. Veretin arxiv: , A. Hayreter and G. Valencia arxiv: Important to consider the CEPC sensitivity to Higgs and top EFT, even though the operational energy is far below ttbar+higgs threshold. I will go through the physics probes for these operators individually and by groups

7 Top quark and Higgs EFT O th CP-even and CP-odd type of Yukawas, asymmetries too tiny below ttbar threshold. Sensitivity from loop process. Gluon-gluon and diphoton drives the limits, though the precision of corresponding coupling is worse than κ " measurement. Better than HL-LHC tth direct production. Assuming no new HGG and HFF operators; In cases where HGG and HFF are of the same order, e.g., top partners with mixing, a correlation presents and the constraints on new physics scales are generically still be the same order

8 Top quark and Higgs EFT O bh Direct constraints from H b&b precision. CEPC projection of 1.5% on bottom Yukawaà9 TeV on Λ But that is not all the story.

9 Strong Phase in SM Higgs 2.0 I(τ) Absolute Real Imaginary Top loop τ Bottom loop Charm loop A strong phase in the gluon-gluon fusion production at hadron colliders (imaginary part) All quark contributions normalized the same way, the plot represents the relative contributions Numerically: t-loop b-loop i c-loop i

10 Top quark and Higgs EFT O bh Direct constraints from H b&b precision. Sensitivity to CP-phase phase through interference with top loop for the gluon-gluon-higgs coupling.

11 Joint Analysis O bh and O th Key measurements (CEPC): Higgs to diphoton Higgs to digluon Higgs to bb (tth@lhc) Four d.o.f., bottom and top Yukawa: Strengths (x-axes) and phases (y-axes)

12 Joint Analysis O bh and O th Key measurements (CEPC): Higgs to diphoton Higgs to digluon Higgs to bb (tth@lhc) Bottom Yukawa: H to bb constraints the strength H to digluon constraints the phase through interference Four d.o.f., bottom and top Yukawa: Strengths (x-axes) and phases (y-axes)

13 Joint Analysis O bh and O th Key measurements (CEPC): Higgs to diphoton Higgs to digluon Higgs to bb (tth@lhc) Four d.o.f., bottom and top Yukawa: Strengths (x-axes) and phases (y-axes) Top Yukawa: H to gg constraints the strength and phase (due to loop function differences) H to gamma gamma constraints the phase through interference with dominant W-loop

14 Joint Analysis O bh and O th Bottom Yukawa and top Yukawa: Black: no CP violation; Essentially independent determination of top and bottom Yukawa from H->gg and H->bb process; Blue: common CP phase for top and bottom Yukawa; Having top CP phase allows for a same H->gg a smaller top Yukawa due to loop function differences and less destructive interference between top-loop and W-loop. Brown: general CP phase Allows one to turn destructive interference between top and bottom for H->gg process to constructive. Allows for lower top Yukawa.

15 Joint Analysis O bh and O th Bottom Yukawa: H to bb constraints the strength H to digluon constraints the phase through interference Joint analysis of these two operators, results in faint shaded regions: Relaxing the phase constrain on bottom Yukawa; Relaxing the magnitude and phase constraints on top Yukawa. These are through the modification to the destructive interference between the bottom and top loop to the Higgs to gluon pair couplings. Top Yukawa: H to gg constraints the strength and phase (due to loop function differences) H to gamma gamma constraints the phase through interference with dominant W-loop

16 Top quark and Higgs EFT (7) (:), O45, O4;, O 4< O 45

17 Top quark and Higgs EFT (7) (:) O 45, O45, O4;, O 4< Three-point functions only qqv Higgs modification starting at the four-point function qqvh *little impact on the Higgs coupling precision fitsat tree-level (since most Higgs decay are two-body) **No photon, only Z and W

18 (7) (:) Top quark and Higgs EFT O 45, O45, O4< Δg L b /g L b (%) CEPC/FCC-ee 240 GeV ee 5 ab -1 95% & 68% (TeV 2 /Λ 2 ) (1) C Hb Current Z-pole 95% & 68% e+e- Z-pole (unpol.) 5σ Z Z (%) /g R t Δg R t (1) (TeV 2 /Λ 2 ) C (3) Hq +C Hq Z-pole provides very high precision on these coupling. Z-pole result from S. Gori, J. Gu, and L.-T. Wang

19 (7) (:) Top quark and Higgs EFT O 45, O45, O4< Δg L b /g L b (%) CEPC/FCC-ee 240 GeV ee 5 ab -1 95% & 68% HVbb vertex ee Z bb&h h Zbb Exotic production might provide us useful information about these operators. (TeV 2 /Λ 2 ) (1) C Hb Current Z-pole 95% & 68% (1) (TeV 2 /Λ 2 ) C (3) Hq +C Hq e+e- Z-pole (unpol.) 5σ Z Z Z-pole provides very high precision on these coupling. (%) /g R t Δg R t Z-pole result from S. Gori, J. Gu, and L.-T. Wang

20 (7) (:) Top quark and Higgs EFT O 45, O45, O4; LHC-DY-ttbar is buried under the QCD ttbar production Need ttz, ttw final states ttw(4j)@lhc 3000 fb -1 Δg L t /g L t (%) ttz@lhc 300, 3000 fb (TeV 2 /Λ 2 ) (1) C Ht 0 ttw(3j)@lhc 3000 fb -1 e + e GeV (%) t t Δg R /g R C (3) Hq -C (1) Hq (TeV 2 /Λ 2 ) R. Rontsch and M. Schulze, , J. Dror, M. Farina, E. Salvioni, J. Serra,

21 (7) (:) Top quark and Higgs EFT O 45, O45, O4; LHC-DY-ttbar is buried under the QCD ttbar production Why 365 GeV? Unpolarized Beam ttw(4j)@lhc 3000 fb -1 Δg L t /g L t (%) ttz@lhc 300, 3000 fb σ(e + e - tt)(pb) σ(e + e - tt) σ(e + e - tt) ( s 0 2 s 2 ) Lumi-suppression factor s (GeV) (TeV 2 /Λ 2 ) (1) C Ht ttw(3j)@lhc 3000 fb -1 e + e GeV C (3) Hq -C (1) Hq (TeV 2 /Λ 2 ) (%) /g R t Δg R t R. Rontsch and M. Schulze, , J. Dror, M. Farina, E. Salvioni, J. Serra,

22 (7) (:) Top quark and Higgs EFT O 45, O45, O4; Cross section and forward-backward asymmetry 1.5 Δg L t /g L t (%) dσ(e + e - tt)/dz (pb) ILC 0.5 ab -1 with polarization better than 1.5 ab -1 unpolarized e L - e R + e R - e L + average cosθ (TeV 2 /Λ 2 ) (1) C Ht e + e GeV 0.5 ab -1 4 ab (1) (TeV 2 /Λ 2 ) C (3) Hq -C Hq e + e GeV 1.5 ab ab ab -1 opt. obs (%) /g R t Δg R t

23 (7) (:) Top quark and Higgs EFT O 45, O45, O4; Cross section and forward-backward asymmetry 1.5 Δg L t /g L t (%) dσ(e + e - tt)/dz (pb) ILC 0.5 ab -1 with polarization better than 1.5 ab -1 unpolarized e L - e R + e R - e L + average cosθ Little asymmetry for unpolarized beam (TeV 2 /Λ 2 ) (1) C Ht e + e GeV 0.5 ab -1 4 ab (1) (TeV 2 /Λ 2 ) C (3) Hq -C Hq e + e GeV 1.5 ab ab ab -1 opt. obs (%) /g R t Δg R t

24 (7) (:) Top quark and Higgs EFT O 45, O45, O4; At or above tt threshold at lepton colliders, one immediately again great sensitivities to the top gauge couplings. Optimal observable estimates: P. Janot 15 G.Durieux, M. Perello, M. Vos, C. Zhang Patrick Janot

25 (7) (:) Top quark and Higgs EFT O 45, O45, O4; At or above tt threshold at lepton colliders, one immediately again great sensitivities to the top gauge couplings. (TeV 2 /Λ 2 ) (1) C Ht e + e GeV 0.5 ab -1 4 ab -1 Δg L t /g L t (%) e + e GeV 1.5 ab (%) /g R t Δg R t ab ab -1 opt. obs (1) (TeV 2 /Λ 2 ) C (3) Hq -C Hq Patrick Janot

26 sign(c) Λ/ c (TeV) Top quark and Higgs EFT summary Δy t (O th ) 95% C.L. exclusion on new physics scale Λ Higgs Precision driven 5 HL-LHC+LEP e+e- 250GeV@5ab -1 ( Z) e+e- 250GeV@5ab GeV@1.5ab -1 ( Z) Δy b (O bh ) 10 (3) (1) O Hq +OHq Z-pole driven 10 (1) O Hb (3) (1) O Hq -OHq tt-pair driven (1) O Ht Naturally divide into groups, where the correlations between the measurements are not large at linear level.

27 Top quark and Higgs EFT summary sign(c) Λ/ c (TeV) Δy t (O th ) 95% C.L. exclusion on new physics scale Λ Higgs Precision driven 5 HL-LHC+LEP e+e- 250GeV@5ab -1 ( Z) e+e- 250GeV@5ab GeV@1.5ab -1 ( Z) Δy b (O bh ) 10 (3) (1) O Hq +OHq Z-pole driven 10 Naturally divide into groups, where the correlations between the measurements are not large at linear level. (1) O Hb (3) (1) O Hq -OHq tt-pair driven (1) O Ht Higgs-Top couplings important and interesting. We try to develop some comprehensive understanding of the minimal Higgs Top anomalous coupling EFT set. Higgs precision, Z-pole precision, ttbar (365 GeV) all needed to complete the picture. Might be interesting to consider the synergy and physics outcome of larger ring (100 km) and larger energy (350~400 GeV).

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30 Loop-level constraints from precision Zh measurements

31 Top quark and Higgs EFT DHq-DHq(3), DHt At or above tt threshold at lepton colliders, one immediately again huge sensitivities to the top gauge couplings. Top quark loop can also induce some operator mixing and enter the Z-pole precisions (Altarelli, Barbieri, Caravaglios, 93 ) ε 7, ε <

32 Top quark and Higgs EFT DHq-DHq(3), DHt At or above tt threshold at lepton colliders, one immediately again huge sensitivities to the top gauge couplings. Top quark loop can also induce some operator mixing and enter the Z-pole precisions (Altarelli, Barbieri, Caravaglios, 93 ) ε 7, ε < However, these are essentially R < and A GH. To use them, one have to assume extreme cases of DHq+DHq(3) and DHb both are zero at the same time. Only known example is custodial Zbb Agashe, Contino, De Rold, Pomarol, 06. In addition, there are some controversies about finite pieces in these relations.