CP properties of the Higgs at the ILC. Rohini M. Godbole CP property of the Higgs at the ILC. ♦ Introduction. ♦ Two issues: i Determination of CP for a Higgs which is a CP eigen- state. ii Determination of CP mixing in the Higgs sector for a Higgs with indeterminate CP. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. Rohini M. Godbole R.G, S.Kraml, M.Krawczyk, D.J.Miller, P.Niezurawski and A.F.Zarnecki in G. Wei- glein et al., Phys. Rept. 426 (2006) 47 and hep-ph/0404024. hep-ph/0608079 CPNSH report. R.M. Godbole, Pramana 67 (2006) 835. A. Djouadi, hep-ph/0503172, 0503173. Bhupal Dev,A.D.,R.G.,Muhelleitner, Rindani hep-ph/0707.2848 R.G., D. Miller and M. Muehlleitner: hep-ph/0708.0458 September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. � C P and Higgs Importance of Studies of CP Properties of Higgs Boson • Just the discovery of the Higgs boson is not sufficient to validate the minimal SM. • In SM, the only fundamental neutral scalar is a J PC = 0 ++ state arising from an SU (2) L doublet with Y = +1. • Various extensions of the SM can have several Higgs bosons with different CP properties : e.g. MSSM has two CP -even and one CP -odd states. • Therefore, should a neutral spin-0 particle be detected, a study of its CP - properties would be essential to establish it as the SM Higgs boson. • To study the New Physics effects beyond SM, we need to establish the CP eigenvalues for the Higgs states if CP is conserved, and measure the mixing between CP -even and CP -odd states if it is not. • CP violation in the Higgs sector can be an alternative source of CP violation beyond the SM, required to explain the observed baryon asymmetry in our universe. [Accomando et al., CERN 2006-009 (2006)] September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. Link between � C P in SUSY and Higgs sector Effect of SUSY � C P on Higgs phenomenology MSSM � C P phases ⇒ � C P in the Higgs sector: h,H A CP conserving MSSM Three Neutral Higgses CP -even CP -odd φ 1 , φ 2 , φ 3 CP violation : no fixed CP property m φ 1 < m φ 2 < m φ 3 Sum rules exist for φ i f ¯ f , φ i V V (A. Mendez and A. Pomarol, J.Gunion, H. Haber and J. Wudka, B.Grzadkowski, J.Gunion and J. Kalinowski. ) g 2 φ i W W + g 2 φ j W W + g 2 φ k W W = g 2 m 2 W , i � = j � = k First proposed in a model independent way. The h, H, A now all mix and share the couplings with vector boson pair VV. Will affect production rates. Predictions in terms of SUSY � C P phases in the MSSM for this mixing. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. CP studies in the Higgs sector CP Study in the Higgs sector (R.G., Kraml, Krawczyk,Miller et al in LHC/LC study group report.) 1. Determination of the CP properties of the Spin 0 particle(s) which we hope will be discovered at the future colliders. 2. Determination of the CP mixing if discovered scalars ( ≃ Higgses) NOT CP eignestates. Establish tensor structure for φ i f ¯ f , φ i V V vertex. φ i : a generic Higgs. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. CP studies in the Higgs sector General Strategy for CP determination: Couplings with pair of gauge bosons ( ZZ/γγ/WW ) and the pair of heavy fermions ( t/τ ) are the ones which are useful. Study � C P in a model indpendent way (most studies so far) f ( s f + ip f γ 5 ) gm f φ i f ¯ − ¯ f : , 2 m W gm 2 V V V φ i : a V g µν (V = W / Z , g : tree / loop level) m W ηǫ µνρσ p ρ k σ /m 2 : Z (loop level) 1. SM: s f = c V = 1 , p f = 0 ,i = 1. 2. s f = c V = 0 and p f � = 0 for the CP odd Higgs, for general CP conserving multi-Higgs models. 3. Pseudoscalar ǫ µνρσ : only at loop level in MSSM and CP conserving 2HDM. 4. Generically CP mixing is a loop effect, hence small. September 12, 2007 , Florence, GGI.
ILC: e + e − and γγ . CP properties of the Higgs at the ILC. Collider CP determination Measurement of Mixing f ¯ f ¯ ILC f Higgs final state f Higgs final state V V, f ¯ V V, f ¯ f final states f final state γγ VV final state Best for study VV fusion of mixing V V and f ¯ f final state angular distributions show striking differences due to the differences in the tensor structure. Most important advanatge for t ¯ tH final state and γγ colliders: Production channel treats both the scalar and the pseudscalar the same way. Then use all the same methods as at other colliders. The most unambigious way to measure CP mixing. γγ colliders possible with backscattered lasers at a parent e + e − collider. Likely to be in the far future. M. Krawczyk’s talk? September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. CP diganostics • Use kinematic distribution of the decay products of the Higgs: H → ff ′ ¯ f ( f = t, τ ), H → ZZ ( Z ∗ ) → f ¯ f ′ . f ¯ • What distributions: Angular distributions, invariant mass distribu- tions, angular correlations. • Kinematics of the production process, threshold rise. • Spin information of the fermions produced in the decay of Higgs or the fermions which are produced in association with the Higgs. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. Importance of t/τ in Higgs Phys. • For the τ decay products carry the spin information of the decaying τ . Due to its large decay width (Γ t ∼ 1 . 5 GeV), top also decays much before hadronization; hence its spin information is translated to the decay distribution before being t, φ → τ + τ − and e + e − → t ¯ contaminated by hadronisation effects. Hence φ → t ¯ tφ carry information on CP character of Φ. • The decay lepton angular distribution for the t is independent of any non- standard effects in the top decay vertex. Thus this distribution is a pure probe of new physics associated with the t -production [e.g. Godbole, Rindani, and Singh, JHEP 12 , 021 (2006)]. Lepton angular distribution a good po- lariometer. Measuring decay lepton angular distribution asymmetries can give information on produced top polarisation asymmetries. September 12, 2007 , Florence, GGI.
Light Higgs CP properties of the Higgs at the ILC. For a light Higgs, most promising, at an ILC, is to exploit the ZZ ( Z ∗ ) coupling for production , H → ZZ ( ∗ ) → f ¯ ff ′ ¯ f ′ , H → τ + τ − . a)Energy dependecne of the total production cross-section in Hig- gsstahlung. b)Production angular distribution. c)Angular correlations. Zerwas, Djouadi, Barger, Kniehl, Keung, Choi, Miller, Osland,Kraemer,Was, Desch, Worek,Choi, J.S. Lee, Pilaftsis.... September 12, 2007 , Florence, GGI.
Threshold behaviour e + e − → Zφ CP properties of the Higgs at the ILC. � σ ( e + e − → HZ ) ∼ λ 1 / 2 ∼ s − ( M H + M Z ) 2 σ ( e + e − → ZA ) = η 2 G 2 µ M 6 λ 3 / 2 Z a 2 v 2 (ˆ e + ˆ e ) 48 πM 4 (1 − M 2 Z /s ) 2 A 100 � = H 10 � = A + � 1 � ( e e ! Z �) [fb℄ 15 M = 120 GeV � cross section (fb) 0.1 J=0 10 J=1 0.01 210 212 214 216 218 220 p s [GeV℄ J=2 5 0 210 220 230 240 250 s (GeV) Threshold rise can determine spin, and can discriminate against 0 − , 1 − etc. Angular distributions sensitive to Parity as well. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. Angular distributions & correlations d σ ( e + e − → ZH ) ∼ λ 2 sin 2 θ + 8 M 2 Z /s d cos θ d σ ( e + e − → ZA ) ∼ 1 + cos 2 θ 1 d cos θ p s = 500 GeV (1 =� )d � = d os � M = 120 GeV H 0.8 + � e e ! Z H 0.6 0.2 1.7 < O > SM tot + � σ tot ( η )/ σ e e ! Z A 0.15 1.6 0.4 0.1 < O > 1.5 + � 0.2 e e ! Z Z 0.05 1.4 0 0 1.3 -1 -0.5 0 0.5 1 os � -0.05 1.2 -0.1 1.1 SM -0.15 σ tot ( η )/ σ 1 tot -0.2 0.9 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 η Even CP mixing can be measured using this. Next is angular correla- tions and azimuthal distributions. September 12, 2007 , Florence, GGI.
CP properties of the Higgs at the ILC. Angular correlations θ ∗ Z θ e + e − H d σ ( e + e − → ZH ) ∼ 1 + a 1 cos φ ∗ + a 2 cos 2 φ ∗ d φ ∗ d σ ( e + e − → ZA ) ∼ 1 − 1 4 cos 2 φ ∗ d φ ∗ φ ∗ azimuthal angle of the plane of Z → f ¯ f decay and Higgs decay products. September 12, 2007 , Florence, GGI.
CP information from H → ZZ ( Z ∗ ) CP properties of the Higgs at the ILC. The definition of the polar angles θ i ( i = 1 , 2) and the azimuthal angle ϕ for the ' f f 2 1 sequential decay H → Z ( ∗ ) Z → ( f 1 ¯ f 1 )( f 2 ¯ f 2 ) in the rest frame of the Higgs boson. � � 2 1 Z H Z � � f f 2 1 Need to distinguish between f 1 and ¯ f 1 . One Z decays to f 1 ¯ f 1 and other two f 2 ¯ f 2 . In the SM d Γ 0.5 dϕ ∼ 1 + A cos ϕ + B cos 2 ϕ 1, 0, 0 (SM) 0.45 0, 0, 1 1, 0, 2 0.4 1, 0, 1 A, B are funtions of M H , M Z . the φ 1 d Γ __ __ Γ d φ 0.35 dependence will vanish for larger Higgs 0.3 masses. 0.25 For CP odd case 0.2 π 0 π /4 π /2 3 π /4 φ d Γ dϕ ∼ 1 − 1 4 cos 2 ϕ September 12, 2007 , Florence, GGI.
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