A Geometric Approach to CP Violation: Applications to the MCPMFV SUSY Model Jae Sik Lee National Center for Theoretical Sciences, Hsinchu, TAIWAN NCTS HEP Journal Club, November 9, 2010 ∗ based on JHEP 1010:049,2010, arXiv:1006.3087 [hep-ph] and arXiv:1009.1151 [math.OC] with J. Ellis and A. Pilaftsis ♠ Preliminary • The SUSY models such as the MSSM contain many possible sources of flavour and CP violation in the soft SUSY-breaking sector: 30 ⊕ 33 ⊕ 46 = 109 !!! – Gaugino mass terms: 3 ⊕ 3 = 6 1 fW f + M1 B eB e + h.c.) −Lsoft ⊃ (M3 gege + M2 W 2 – Trilinear a terms af ij ≡ hf ij · Af ij : 3 × (3 ⊕ 6 ⊕ 9) = 54 e 2 − de∗R ad QH e 1 − ee∗R ae LH e 1 + h.c.) −Lsoft ⊃ (e u∗R au QH – Sfermion mass terms: 5 × (3 ⊕ 3 ⊕ 3) = 45 2 ∗ e∗ M2 deR + ee∗ M2 eeR e † M2 Q e+L e † M2 L e+u −Lsoft ⊃ Q M u e + d e R R R R e e e e e u e Q L d – Higgs mass terms: 3 ⊕ 1 = 4 † † 2 2 2 −Lsoft ⊃ MH H M H H + H − (m 2 1 H 12H1 H2 + h.c.) 2 u d 1 ♠ Preliminary • Recently, we have suggested MCPMFV framework with the maximal set of flavour-singlet mass scales: J. Ellis, JSL and A. Pilaftsis, Phys. Rev. D 76 (2007) 115011, [arXiv:0708.2079 [hep-ph]] M1,2,3 , 3⊕3 2 2 f 2Q,L,U,D,E = M fQ,L,U,D,E MH , M 13 , Au,d,e = Au,d,e 13 u,d 2 3⊕3 5 13 ⊕ 6 = 19 Parameters ! For related approaches, see, M. Argyrou, A. B. Lahanas and V. C. Spanos, JHEP 0805 (2008) 026; [arXiv:0804.2613 [hep-ph]] G Colangelo, E. Nikolidakis and C. Smith, Eur. Phys. J. C 59 (2009) 75; [arXiv:0807.0801 [hep-ph]] W. Altmannshofer, A. J. Buras and P. Paradisi, Phys. Lett. B 669 (2008) 239; [arXiv:0808.0707 [hep-ph]] L. Mercolli and C. Smith, Nucl. Phys. B 817 (2009) 1; [arXiv:0902.1949 [hep-ph]] A. L. Kagan, G. Perez, T. Volansky and J. Zupan, Phys. Rev. D 80 (2009) 076002; [arXiv:0903.1794 [hep-ph]] R. Zwicky and T. Fischbacher, Phys. Rev. D 80 (2009) 076009; [arXiv:0908.4182 [hep-ph]] J. Ellis, R. N. Hodgkinson, JSL and A. Pilaftsis, JHEP 1002 (2010) 016; [arXiv:0911.3611 [hep-ph]] ♠ Preliminary • Then, who ordered ”more” CP violation beyond the SM CKM phase?A. D. Sakharov, JETP Letters 5(1967)24 CP violation in the SM is too weak to explain the matter dominance of the Universe J. Cline, arXiv:hep-ph/0609145 The matter-dominated Universe did! ♠ Preliminary • Electric Dipole Moments (EDMs): T violation ⇒ CP violation (under CPT ) HEDM = −d E · ŝ |dTl| < 9 × 10−25 e cm , |dHg | < 3.1 × 10−29 e cm , |dn| < 3 × 10−26 e cm B. C. Regan, E. D. Commins, C. J. Schmidt and D. DeMille, PRL88 (2002) 071805; W. C. Griffith, M. D. Swallows, T. H. Loftus, M. V. Romalis, B. R. Heckel and E. N. Fortson, PRL102 (2009) 101601; C. A. Baker et al., PRL97 (2006) 131801 Question: No large CP phases? ♠ Preliminary • A scan method: See, for example, V. D. Barger, T. Falk, T. Han, J. Jiang, T. Li and T. Plehn, Phys. Rev. D 64 (2001) 056007 [arXiv:hep-ph/0101106]. 15 parameter MSSM 2 2 θµ/π θµ/π 1.5 1.5 1 1 0.5 0.5 0 0 0.5 1 1.5 2 0 ⋄ 15 parameter MSSM: 100 100 0 0 0 0.5 1 1.5 φ1/π 0 GeV GeV GeV GeV 2 ≤ ≤ ≤ ≤ ≤ ≤ θµ, φ1,3 , θA d,e,u,t µ 2M1 , M2 , M3 |A| mẽR , mũR tan β ≤ ≤ ≤ ≤ ≤ ≤ 2π 1 TeV 1 TeV 1 TeV 1 TeV 10 2 φ3/π 2 2 θµ/π θµ/π 1.5 1.5 1 1 Open circles suffer from parameter tuning ∆X/X worse than 0.5 0.5 0 0 2 4 6 8 10 tan β 1%. Green dots correspond to configurations with a light Higgs mh < 113 GeV. 10 -2 10 -1 tuning ∆X/X 1 ♠ Preliminary • A scan method: See, for example, V. D. Barger, T. Falk, T. Han, J. Jiang, T. Li and T. Plehn, Phys. Rev. D 64 (2001) 056007 [arXiv:hep-ph/0101106]. 23 parameter MSSM 2 2 θµ/π θµ/π 1.5 1.5 1 1 0.5 0.5 0 0 0.5 1 1.5 2 0 ⋄ 23 parameter MSSM: 0 0.5 1 1.5 2 2 θµ/π θµ/π 1.5 1.5 1 1 0.5 0.5 0 2 4 6 8 10 tan β 2 φ3/π 0 GeV ≤ mq̃L ,mũR ,md˜ ≤ 1 TeV 0 GeV ≤ mq̃ 3 ,mt̃ ≤ 1 TeV 2 ≤ 0 10 -2 10 -1 tuning ∆X/X 1 2π 1 TeV 1 TeV 1 TeV 1 TeV θµ , θMi , θAi µ 2M1 , M2 , M3 |Ad,e,u,t | mℓ̃ ,mẽR 100 100 0 0 φ1/π ≤ ≤ ≤ ≤ ≤ ≤ ≤ ≤ ≤ ≤ 0 GeV GeV GeV GeV L L tan β R R ≤ 10 ♠ Preliminary 300 250 CS 10 100 200 dEe 150 100 1 50 10 3 350 E 200 300 10 ΦA [ o ] -1 0 0 100 200 300 0 Φ3 [ o ] 100 200 250 d ΦA [ o ] 350 300 250 200 150 100 G 200 10 Cbd 10 300 | dn(QCD) / dEXP | 100 300 10 2 150 100 ρ=1 o ΦA = 60 1 Φ3 [ o ] 0 C d u,d du,d 50 0 -1 0 10 3 100 ρ=1 10 2 d u,d C ΦA = 60 CS 300 0 Φ3 [ o ] ΦA = 60 o 100 200 10 CP(’) 10 300 ΦA [ o ] 350 300 C d u,d 250 200 10 150 E du,d 100 1 o C4f 1 0 200 ρ=3 10 2 10 3 dEe 50 50 -1 0 10 3 100 200 ρ=3 10 2 300 Φ3 [ o ] ΦA = 60 o C d u,d 10 1 50 0 0 dTl | dHg / dEXP | 150 10 2 350 | dHg / dEXP | 200 o Φ3 [ o ] 250 ΦA = 60 Φ3 [ o ] 300 10 3 | dn(QCD) / dEXP | 350 J. R. Ellis, JSL and A. Pilaftsis, JHEP 0810 (2008) 049 [arXiv:0808.1819 [hep-ph]] Φ3 [ o ] Φ3 [ o ] | dTl / dEXP | • A scan method: 100 200 300 10 ΦA [ ] o -1 0 0 100 QCD dn 200 300 Φ3 [ ] o 0 100 200 300 10 ΦA [ ] o -1 0 100 dHg 200 300 Φ3 [ o ] ♠ Preliminary • A scan method is like “shooting in the dark” ... blind, time consuming, no guiding principle, etc Any analytic, exact, and more effective method? ⇒ A Geometric Approach to CP violation ♠ Optimal Direction • A linear approximation: We consider the case with N CP-violating phases In the N -dimensional CP-phase space, we define N −D phase vector Φ = (Φ1, Φ2, · · ·, ΦN ) and then any CP-odd observable O and any EDM E can be expanded as O = Φ · O + ··· ; E = Φ · E + ··· Formally, we define O ≡ ∇O ; with ∇ ≡ (∂/∂φ1, ∂/∂φ2, · · · , ∂/∂φN ) E ≡ ∇E ♠ Optimal Direction • [Simple 3D example] with 3 CP phases and 1 EDM constraints: EDM-free subspace and Optimal direction in the linear approximation EDM vector An Observable vector ∗ Φ = E × (O × E) An Optimal direction CP-phase space Subspace of EDM-free directions ♠ Optimal Direction • The higher-dimensional generalization with N The CP phases and n EDM constraints N -dimensional vector of the optimal direction ∗ Φ α (1) = ǫαβ1···βnγ1···γ N −n−1 (n) E β1 · · · E βn B γ1···γN −n−1 where (N -n-1)-dimensional B form is B γ1···γN −n−1 = ǫγ1···γ (1) N −n−1 The maximum allowed value of O is: (n) O E · · · E βn σβ1 ···βn σ β1 b∗ · O Omax = (φ∗)max Φ with the b ∗ and φ∗ which may be practically determined by the validity of the small-phase normalized optimal-direction vector Φ approximation of the EDMs. ♠ Optimal Direction • How good is the linear approximation? The quadratic fit to the Thallium EDM that is used to obtain the 6D vector E dTl ≡ ∇(dTl /dEXP eα = 0◦ for the MCPMFV scenario: Tl ) in an expansion around ϕ ˛ ˛ f2 = (100 GeV)2 , |Au | = f2 = M f2 = M f2 = M f2 = M ˛M1,2,3 ˛ = 250 GeV , M 2 = M 2 = M E L D U Q H Hu d 0 -100 500 250 -250 -0.2 10 o Φ2 [ ] -10 0.2 0 0 10 Φ3 [ ] o EXP 0 dTl / dTl EXP 0 -0.4 -10 dTl / dTl 0.01 0.2 0 10 o Φ1 [ ] EXP 0 0.4 0 -500 -10 dTl / dTl EXP 100 dTl / dTl EXP dTl / dTl dTl / dTl EXP |Ad | = |Ae | = 100 GeV , and tan β = 40. 1 0.5 0 -0.5 -0.01 -0.2 -10 0 10 ΦAu [ ] o -1 -10 0 10 ΦAd [ ] o -10 0 10 ΦAe [ ] o ♠ Numerical Illustration • We are considering J. Ellis, JSL, and A. Pilaftsis, JHEP 0810:049,2008, arXiv:0808.1819 [hep-ph] ; K. Cheung, O. C. W. Kong, and JSL, JHEP 0906:020,2009, arXiv:0904.4352 [hep-ph]; J. Ellis, JSL and A. Pilaftsis, Phys. Rev. D 76 (2007) 115011, [arXiv:0708.2079 [hep-ph]] – Thallium EDM – Neutron EDM – Mercury EDM – Deuteron EDM – muon EDM – ACP(b → sγ) These are all implemented in CPsuperH2.2 ♠ Numerical Illustration • Thallium EDM;I.B. Khriplovich and S.K. Lamoreaux, CP Violation Without Strangeness (Springer, New York, 1997); M. Pospelov and A. Ritz, Annals Phys. 318 (2005) 119,[arXiv:hep-ph/0504231] −19 dTl [e cm] = −585 · dE [e cm] · (CS TeV2) + · · · e [e cm] − 8.5 × 10 dE e CS = = E χ̃± E χ̃0 (de ) + (de ) + (CS )4f + (CS )g H (dE e) MeV MeV where (CS )4f = Cde 29m + Cse κ×220 with κ ≡ hN |mss̄s|N i/220 MeV ≃ ms d 0.50 ± 0.25 and 3 S P X g g m H gg H e i i ēe (CS )g = (0.1 GeV) 2 2 v i=1 MH i ♠ Numerical Illustration • Neutron EDM [QCD sum rule techniques (QCD)];M. Pospelov and A. Ritz, Phys. Rev. Lett. 83 (1999) 2526, [arXiv:hep-ph/9904483]; M. Pospelov and A. Ritz, Nucl. Phys. B 573 (2000) 177, [arXiv:hep-ph/9908508]; M. Pospelov and A. Ritz, Phys. Rev. D 63 (2001) 073015, [arXiv:hep-ph/0010037]; D. A. Demir, M. Pospelov and A. Ritz, Phys. Rev. D 67 (2003) 015007,[arXiv:hep-ph/0208257]; D. A. Demir, O. Lebedev, K. A. Olive, M. Pospelov and A. Ritz, Nucl. Phys. B 680 (2004) 339, [arXiv:hep-ph/0311314]; K. A. Olive, M. Pospelov, A. Ritz and Y. Santoso, Phys. Rev. D 72 (2005) 075001, [arXiv:hep-ph/0506106] C G dn = dn(dE q , dq ) + dn (d ) + dn (Cbd ) + · · · , C E E C C dn(dE , d ) = (1.4 ± 0.6) (d − 0.25 d ) + (1.1 ± 0.5) e (d + 0.5 d q q d u d u )/gs , dn(d G) ∼ ± e (20 ± 10) MeV d G , Cdb Cbd + 0.75 dn(Cbd) ∼ ± e 2.6 × 10−3 GeV2 mb mb where dG = dG(1 GeV) ≃ 8.5 dG(EW) ♠ Numerical Illustration • Mercury EDM;D. A. Demir, O. Lebedev, K. A. Olive, M. Pospelov and A. Ritz, Nucl. Phys. B 680 (2004) 339, [arXiv:hep-ph/0311314]; K. A. Olive, M. Pospelov, A. Ritz and Y. Santoso, Phys. Rev. D 72 (2005) 075001, [arXiv:hep-ph/0506106] C −2 E dHg = 7 × 10−3 e (dC de u − dd )/gs + 10 Csd Cbd 2 0.5Cdd −5 + 3.3κ + (1 − 0.25κ) − 1.4 × 10 e GeV md ms mb + (3.5 × 10−3 GeV) e CS " −4 + (4 × 10 GeV) e CP + Z −N A CP′ Hg # where LCP = CP ēe N̄ iγ5N + CP′ ēe N̄ iγ5τ3N with CP = (CP ) 4f ≃ − 375 MeV X q=c,s,t,b CP′ = (CP′ )4f Ceq , mq Ced − 181 MeV ≃ − 806 MeV md X q=c,s,t,b Ceq mq ♠ Numerical Illustration • Deuteron EDM;O. Lebedev, K. A. Olive, M. Pospelov and A. Ritz, Phys. Rev. D 70 (2004) 016003,[arXiv:hepph/0402023] dD ≃ − 5+11 −3 C + (0.6 ± 0.3) e (dC − d u d )/gs C E E −(0.2 ± 0.1) e (dC + d )/g + (0.5 ± 0.3)(d + d s u d u d) 0.5C C C dd sd bd + 3.3κ + (1 − 0.25κ) +(1 ± 0.2) × 10−2 e GeV2 md ms mb ± e (20 ± 10) MeV d G The projective sensitivity: Y. K. Semertzidis et al. [EDM Collaboration], AIP Conf. Proc. 698 (2004) 200, [arXiv:hep-ex/0308063]; Y. F. Orlov, W. M. Morse and Y. K. Semertzidis, Phys. Rev. Lett. 96 (2006) 214802, [arXiv:hep-ex/0605022]; and also see http://www.bnl.gov/edm/deuteron proposal 080423 final.pdf |dD | < 3 × 10−27 − 10−29 e cm For our numerical study, we take 3 × 10−27 e cm as a representative expected value ♠ Numerical Illustration • CP-violating QCD θ-term: O. Lebedev, K. A. Olive, M. Pospelov and A. Ritz, Phys. Rev. D 70 (2004) 016003, [arXiv:hep-ph/0402023]; M. Pospelov and A. Ritz, Annals Phys. 318 (2005) 119, [arXiv:hep-ph/0504231]; J. Ellis, JSL, and A. Pilaftsis, arXiv:1006.3087 [hep-ph] αs L= θ̄ Gaµν G̃µν,a 8π with θ̄ = θQCD + Arg Det Mq |hq̄qi| −16 dn(θ̄) = (1 ± 0.5) θ̄ × 2.5 × 10 e cm (225 MeV)3 dHg(θ̄) ≃ +2.0 × 10−6 θ̄ e GeV−1 ≃ 3.9 × 10−20 θ̄ e cm dD (θ̄) ≃ −e [(3.5 ± 1.4) + (1.4 ± 0.4)] × 10−3 θ̄ GeV−1 ≃ −9.7 × 10−17 θ̄ e cm ♠ Numerical Illustration • [Summary] EDMs and Observables under consideration dTl/dEXP , dn/dEXP , dHg /dEXP Tl n Hg , , ACP(b → sγ)[%] , , dµ/dEXP dD/dEXP µ D where we choose the following normalization factors −29 −26 EXP −25 EXP = 3.1 × 10 e cm , = 3 × 10 e cm , d = 9 × 10 e cm , d dEXP Hg n Tl = 1 × 10−24 e cm = 3 × 10−27 e cm , dEXP dEXP µ D ♠ Numerical Illustration • The EDMs and Observables under consideration are functions of 7 parameters : Φ1 , Φ2 , Φ3 , ΦAu , ΦAd , ΦAe , θ̄ and then ∇α ≡ ∂ ∂ ∂ ∂ ∂ ∂ ∂ , , , , , , ∂Φ1 ∂Φ2 ∂Φ3 ∂ΦAu ∂ΦAd ∂ΦAe ∂ θb The CP-violating phases Φ1,2,3 and ΦAu ,Ad,Ae are specified in degrees and we normalize θ̄ in units of 10−10: θb ≡ θ̄ × 1010 ♠ Numerical Illustration • A scenario: We consider CP-violating variants of a typical CMSSM scenario with |M1,2,3| = 250 GeV , 2 2 2 2 fQ fU2 = M fD fL2 = M fE2 = (100 GeV)2 , MH = M = M = M = M H u d |Au| = |Ad| = |Ae| = 100 GeV , at the GUT scale, varying tan β (MSUSY ) We adopt the convention that Φµ = 0◦, and we vary independently the following six MCPMFV phases at the GUT scale: Φ1 , Φ2 , Φ3 , ΦAu , ΦAd , ΦAe in addition to the QCD θ term: θ̄ This scenario becomes the SPS1a point when tan β = 10, Φ1,2,3 = 0◦ and ΦAu ,A ,Ae = 180◦ d ♠ Numerical Illustration b∗ • Components of the vectors E ≡ ∇E , O ≡ ∇O ; Φ ∧ -3 10 1 10 10 10 -1 10 1 10 -3 20 40 tanβ 2 10 -1 -3 20 40 tanβ 10 10 10 | [ ACP optimal ] α | [ dµ optimal ] -2 10 40 |Φ ∧* |Φ 20 ∧* α | [ dD optimal ] α -3 10 -3 20 tanβ 40 1 10 10 10 -1 -2 -3 20 tanβ 40 tanβ ∧ 1 10 -2 10 40 10 1 -1 -2 -3 -4 20 40 10 10 -1 -2 ∧ : | Φ*2| 10 ∧ : | Φ*3| -1 ∧ − − − : | Φ*Au| 10 -2 ∧ − − − : | Φ*Ad| ∧ − − − : | Φ*Ae| 10 -3 20 tanβ d : | Φ*1| 1 ∧ 10 10 -2 20 -2 tanβ | Oα | [ ACP ( % ) ] EXP 10 2 -3 tanβ | Oα | [ dµ / dµ ] EXP | Oα | [ dD / dD ] tanβ 10 40 -2 10 | [ ∆Φ2,3 = θ = 0 ] 20 -1 -1 1 α 10 40 -1 ∧ 20 10 10 ∧* -3 -2 10 1 |Φ 10 -1 ∧* 10 1 |Φ 1 10 | [ ∆Φ1,Ae = θ = 0 ] 10 -2 10 10 2 α 10 -1 10 2 ∧* 1 − − − : ΦAd |Φ 10 − − − : ΦAu EXP EXP 10 2 10 : Φ3 | Eα | [ dHg / dHg ] : Φ2 | Eα | [ dn(QCD) / dn ] EXP | Eα | [ dTl / dTl ] : Φ1 −−−:θ − − − : ΦAe 40 10 -3 20 tanβ 40 ∧ −−− :|θ| tanβ dTl dn dHg ∗ b Φ α = N εαβγδµνρ Eβ Eγ Eδ Bµνρ dHg with the 3-form Bµνρ = εµνρλστ ω Oλ EσTl Eτdn Eω (1) (2) (3) or Nµ Nν Nρ for some reference directions ♠ Numerical Illustration b∗ · O • The products Φ b∗ · O Recall the relation O max = (φ∗)max Φ ∧ ∧ -2 ∼ φ =0 EXP α 1 o α 10 -3 10 10 -1 10 -2 20 40 tanβ ∼ φ =0 10 -4 -5 20 40 tanβ o α 10 ∧* ∧ ∧* | Φ ⋅ O [ dD / | Φ* ⋅ O [ dµ / dµ ] | ∼ φ = 0o 10 | Φ ⋅ O [ ACP ( % ) ] | 10 EXP dD ] | : dD dir. − − : dµ dir. ⋅ ⋅ ⋅ ⋅ : ACP dir. : ∆Φ1,Ae=θ=0 dir. : ∆Φ2,3=θ=0 dir. 10 10 -2 -3 -4 20 40 tanβ ♠ Numerical Illustration • The maximum values of the observables along the optimal directions tan β = 10 b∗ · O Again, recall the relation O max = (φ∗ )max Φ ∧ ∧ o α 6 4 o α 0.3 0.2 4 3 1 0 0 0 -2 -0.1 -1 -4 -0.2 -6 -0.3 -8 -0.4 0 0 o α 60 0.4 ~ φ =0 o 0.2 40 0 0 0 -0.1 -0.02 -0.2 -0.04 -0.3 -0.06 -50 0 50 φ* -0.4 -50 0 50 φ* 50 ~ ⋄ The maximum values of the observables o α 0.04 -20 -100 0 φ =0 0.06 0.02 -80 -50 0.08 0.1 -60 which are mainly constrained by dTl , dTl , dTl , dHg , and dTl , respectively. φ* 20 -40 e * α 0.3 -4 50 φ EXP ~ φ =0 80 -50 for each ` ∗ ´max φ ∼ 25 (dD -optimal) , 25 (dµ -optimal) , 50 (ACP -optimal) , 40 (∆Φ1,A = θb = 0) , and 45 (∆Φ2,3 = θb = 0), -3 * dµ / dµ 100 -0.5 50 ⋄ The maximum values of φ∗ EDM-free direction from the figure: o α -2 ACP [ % ] -50 ∼ φ =0 2 0.1 φ EXP ∼ φ =0 : ∆Φ2,3=θ=0 dir. 2 -10 dD / dD 0.4 EXP φ =0 8 0.5 dHg / dHg ∼ EXP 10 dn(QCD) / dn dTl / dTl EXP : dD dir. − − : dµ dir. ⋅⋅⋅⋅⋅ : ACP dir. : ∆Φ1,Ae=θ=0 dir. -0.08 -50 0 50 φ* ♠ Numerical Illustration • The maximum values of the CP phases along the optimal directions tan β = 10 ∧ 20 o Φ3 [ ] 10 o Φ2 [ ] 40 o Φ1 [ ] : dD dir. − − : dµ dir. ⋅⋅⋅⋅⋅ : ACP dir. : ∆Φ1,Ae=θ=0 dir. 5 ∧ : ∆Φ2,3=θ=0 dir. 2 1 0 0 0 -20 -5 -1 In the top panels we see that Φ1 and Φ2` can´ be as large max as ∼ 20◦ and ∼ 5◦, respectively, for φ∗ ∼ 25 along the dD - and dµ -optimal directions denoted by the thick solid and dashed lines. -2 -50 0 50 * φ -50 o o 20 40 20 0 0 -20 -20 -40 -40 -40 50 * φ -50 0 50 * φ 181 180 179 We also note in the middle and bottom panels that the phases of Ad,u,e could be are large, in general, though they are suppressed at the MSUSY scale. -50 ΦAτ ( MSUSY )[ ] 190 0 50 * φ 220 o o 182 50 * φ 20 0 0 0 40 -20 ΦAb ( MSUSY )[ ] o -10 50 * φ 40 -50 ΦAt ( MSUSY )[ ] 0 ΦAe [ ] -50 ΦAd [ ] o ΦAu [ ] -40 185 180 175 200 Finally, we note (not shown) that θ̄ could be as large as 180 160 178 -50 0 50 * φ 170 -50 0 50 * φ 140 -50 0 50 * φ ∼ 2 × 10−9 along the dD- and dµ-optimal directions ` ´max with φ∗ ∼ 25. ♠ Summary • We are proposing a geometric method which provides an accurate parametric determination of the optimal cancellation regions where any given physical observable is maximized in the linear approximation • Our geometric approach is exact, efficient and less computationally-intensive than a naive scan of a multi-dimensional space • This constitutes an analytic solution to the so-called linear programming problem • You may want to apply this method to your problem if you are trying to achieve the best outcome in a given requirements expressed in linear equations