Composite Higgs and Flavor

Transcription

1 Composite Higgs and Flavor Xiaohong Wu East China University of Science and Technology ICTS, Jun. 6, 2013

2 125GeV SM-like Higgs Discovered p Combined observed γγ observed llll observed γ γ+llll observed γγ+llll+lvlv observed Combined expected ATLAS Preliminary s = 7TeV, Ldt = fb s = 8TeV, Ldt = 13 fb m H [GeV] 0 1σσ 2 3σ 4σ 5σ 6σ 7σ Local p-value 1 CMS Preliminary s = 7 TeV, L = 5.1 fb s = 8 TeV, L = 12.2 fb σ Combined obs. Exp. for SM H H bb H ττ H γγ H WW H ZZ m H (GeV) 1 2σ 3σ 4σ 5σ 6σ 7σ 8σ Now, 125GeV Higgs-like particle found Electroweak symmetry breaking mechanism Higgs mechanism, a possible solution ICTS, Jun. 6, 2013 Xiaohong Wu 1/15

3 125GeV SM-like Higgs Discovered, cont d ATLAS Preliminary W,Z H bb H ττ s = 7 TeV: Ldt = 4.6 fb s = 8 TeV: Ldt = 13 fb (*) H WW s = 8 TeV: Ldt = 13 fb s = 7 TeV: Ldt = 4.7 fb s = 8 TeV: Ldt = 13 fb lνlν m H = GeV H γγ s = 7 TeV: Ldt = 4.8 fb s = 8 TeV: Ldt = 20.7 fb (*) H ZZ 4l s = 7 TeV: Ldt = 4.6 fb s = 8 TeV: Ldt = 20.7 fb Combined s = 7 TeV: Ldt = fb s = 8 TeV: Ldt = fb µ = 1.43 ± Signal strength (µ) Higgs couplings SM-like, H-gauge-gauge, H-fermion-fermion Should also probe Higgs self-interactions to confirm Higgs mechanism New physics should contain SM as an effective theory, at least for Higgsgauge, Higgs-fermion interactions, e.g. MSSM ICTS, Jun. 6, 2013 Xiaohong Wu 2/15

4 Stabilization of the Fermi scale Higgs mass, δm 2 H g2 Λ 2 16π 2 δm 2 H m2 H indicates Λ 1TeV, naturalness 3 paths to proceed unnatural theory, huge fine-tuning of O(MP 2/m2 H ), hierarchy problem natural theory 1: supersymmetry, weakly coupled theory MSSM in danger (little hierarchy), NMSSM=MSSM+singlet natural theory 2: compositeness, strongly coupled theory Higgs as a composite state generated by strong dynamics, similar to π in QCD a light Higgs, pseudo-goldstone boson of a spontaneously broken global symmetry common feature of natural theory: light top partners around TeV scale (scalar or fermion) ICTS, Jun. 6, 2013 Xiaohong Wu 3/15

5 Outline Composite Higgs model partial compositeness Electroweak precision tests S, T, Z b L b L coupling Flavor Confront with direct CPV in D decays Summary ICTS, Jun. 6, 2013 Xiaohong Wu 4/15

6 Partial Compositeness massless elementary particle interacts with composite operator with a linear mass term, D. B. Kaplan, 1991, similar to γ ρ mixing in QCD SM fermion Yukawa matrix, (ǫ = λ/g ρ ) y u = ǫ ul Y u ǫ ur y d = ǫ dl Y d ǫ dr same mechanism for weak gauge boson W ±, Z mass generation Higgs as pgb in strong sector of spontaneously broken global symmetry, mass generated via explicitly breaking global symmetry, e.g. heavy top ICTS, Jun. 6, 2013 Xiaohong Wu 5/15

7 Composite Higgs model in 5D the minimal composite Higgs model in AdS 5, Agashe, Contino, Pomarol, 2005 calculable via AdS/CFT correspondence ICTS, Jun. 6, 2013 Xiaohong Wu 6/15

8 Composite Higgs model two-sector model with partial compositeness (linear mixing with mass term), Contino, Kramer, Son, Sundrum, 2007 mass spectra Barbieri, Buttazzo, Sala, Straub, Tesi, 2013 simplified assumptions for composite sector: common g ρ, Y, m ρ, m ψ m ρ 3TeV (spin) m ψ 1TeV (spin/2), LHC direct search bounds around GeV m H = 125GeV (spin-0), pgb ICTS, Jun. 6, 2013 Xiaohong Wu 7/15

9 Electroweak Precision Tests S parameter tree-level contribution S = 8πv2 m m 2 ρ 3TeV ρ T parameter, depend on fermion rep. custodial symmetry to protect T parameter SU(2) L SU(2)R SU(2) C SU(3) C SU(2)L SU(2)R U(1)X in composite sector Z b L b L coupling precisely measured at LEP, need to be protected, SU(2) L SU(2)R PLR, Agashe, Contino, Da Rold, Pomarol, 2006 choices of rep. 1. (2,2) 2/3( 1/3) (1,1)2/3( 1/3) 2. (2,2) 2/3 (1,3)2/3 (3,1)2/3 In the former case, left up mixing and left down mixing can be seperated, convenient for flavor model ICTS, Jun. 6, 2013 Xiaohong Wu 8/15

10 An example of Composite Higgs model elementary sector, SU(2) L U(1)Y, massless SM particles q L (2) 1/6, u R (1) 2/3, d R (1) 1/3, g, W µ ±, A µ, Z µ composite sector, SU(2) L SU(2)R U(1)X, massive gauge bosons H(2,2) 0 [ ] T T5/3 Q = = (2,2) B T 2/3, T = (1,1)2/3 2/3 [ ] Q B 1/3 T 1/3 = B 4/3 B = (2,2) 1/3, B = (1,1) 1/3 the Lagrangian, Vignaroli, 2012 L = q i Li q i L+ū i Ri u i R+ d i Ri d i R +Tr { Q(i MQ )Q } + T (i M T ) T +Y U Tr { QH } T +Tr { Q ( i M Q ) Q } + B(i M B ) B +Y D Tr { Q H } B L1 q 3 L(T,B) R1 t R T L2 q 3 L(T,B ) R2 br B +h.c. ICTS, Jun. 6, 2013 Xiaohong Wu 9/15

11 Flavor Anarchy, yukawa couplings y u = ǫ ul Y u ǫ ur y d = ǫ dl Y d ǫ dr Y u,d are anarchic, light fermion with small yukawa coupling from small mixing light quarks are elementary, top strongly composite tree-level FCNC, but suppressed by light quark mass Flavor changing Z Couplings, K L (B S ) µ + µ not enough for Kaon, from Q LR S, m ρ > TeV need flavor symmetry, e.g. SU(3), SU(2) ICTS, Jun. 6, 2013 Xiaohong Wu /15

12 Flavor symmetry Yukawa couplings SU(3) y u = ǫ ul Y u ǫ ur y d = ǫ dl Y d ǫ dr large compositeness of light generation due to heavy top Collider constraint, composite u, d quark within proton MFV setup, no flavor problem SU(2) heavy top not connected to light quarks tree-level FCNC, e.g. Z exchange, heavy gauge boson exchange Redi, Weiler, 2011; Redi, 2012; Barbieri, Buttazzo, Sala, Straub, 2012; Barbieri, Buttazzo, Sala, Straub, Tesi, 2013 ICTS, Jun. 6, 2013 Xiaohong Wu 11/15

13 Direct CPV in D decays Direct CPV in C = 1 c u transition processes D 0 K K + (π π + ) A CP = A CP (D 0 K K + ) A CP (D 0 π π + ) world average (HFAG) by LHCb, CDF, Belle, BaBar before 2013 A CP = [ 0.678±0.147]% LHCb pion tagged analysis, LHCb-CONF A CP = [ 0.34±0.15±0.]% LHCb muon-tagged analysis, A CP = [+0.49±0.30±0.14]% Discussion in SM or NP, from QCD chromomagnetic operator O 8g in NP O 8g = g s m 8π 2 c [ūσ µν T a (1+γ 5 )c]g µν a SUSY, Extra Dimension, Isidori, Kamenik, Ligeti, Perez, 2012; Giudice, Isidori, Paradisi, 2012; Hai-Yang Cheng 2012; Keren-Zur, Lodone, Nardecchia, Pappadopulo, Rattazzi, Vecchi, 2012; Delaunay, Kamenik, Perez, Randall, 2012;... Discussion in a 2HDM and SUSY version, Chao-Shang Huang, Tianjun Li, Xiao-Chuan Wang, XHW, 2013 ICTS, Jun. 6, 2013 Xiaohong Wu 12/15

14 Direct CPV in D decays, cont d Contribution from 4-fermion QCD operators O 4,6 = (ū α c β ) V+A q ( q βq α ) V±A a K + K 0.1% C 4(m c ), with C 4(m c ) 2 gρ 2 G F λ ǫ b m 2 ur ǫ cr ǫ 2 s ρ R g2 ρ ǫ m 2 ur ǫ cr ǫ 2 s ρ R To accomodate A CP, u R, c R, s R (or d R ) should be largely composite Constraints from c = 2 process D 0 D 0 mixing ǫ ur ǫ cr 2 4 s R (or d R ) should be fully composite for A CP a viable model in progress XHW π 2 (3TeV) 2 ICTS, Jun. 6, 2013 Xiaohong Wu 13/15

15 Summary Composite Higgs model is a natural theory beyond the SM. With proper choices of fermion rep. to survive EWPT and flavor symmetry to survive flavor constraints, e.g. B, K Interesting phenomenology in up-type quark sector. ICTS, Jun. 6, 2013 Xiaohong Wu 14/15

16 Thank you for your attention! ICTS, Jun. 6, 2013 Xiaohong Wu 15/15