CP violation in quark flavor physics Stefania Gori University of Cincinnati Testing CP-violation for baryogengesis University of Massachusetts, Amherst, March 29, 2018
Outline and aim of the talk Outline Aims 1. Phases of the CKM unitary triangle Overview 2. Meson mixing Latest updates on the experimental measurements 3. Kaon rare decays Implications on NP theories CP violation in: B mesons Kaons D mesons b → s, b → d s → d c → u During the rest of the workshop, we will learn its connection to baryogengesis S.Gori 2/21
Standard Model flavor & CP (V CKM ) ij Flavor and CP-violation arising from the CKM matrix (V CKM ) Free parameters: ~ 3 real rotation angles and one (CP-violating) phase ( = Cabibbo angle) ( ) Goal: over-constrain sides and angles by many measurements sensitive to different short distance physics S.Gori 3/21
Its success 2004 1995 2016 1.5 excluded at CL > 0.95 excluded area has CL > 0.95 γ 1.0 m & m ∆ ∆ s d sin 2 β 0.5 m ∆ d ε α K β γ η 0.0 α V α ub -0.5 ε γ K -1.0 (68% CL) CKM sol. w/ cos 2 β < 0 f i t t e r (excl. at CL > 0.95) ICHEP 16 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 ρ Remarkable success of the CKM picture! S.Gori 4/21
Measurement of the γ angle 1.5 e x c excluded area has CL > 0.95 l u d e d γ a t C L > 1.0 0 . m & m 9 ∆ ∆ 5 d s sin 2 β 0.5 ∆ m The CKM angle γ is the least known constraint: d ε α K γ β η 0.0 α V α Direct γ measurement Indirect γ extrapolation ub -0.5 ε γ K -1.0 CKM sol. w/ cos 2 β < 0 f i t t e r ICHEP 16 (excl. at CL > 0.95) -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 LHCb expected precision by 2029 (end of Run 4) < 0.4º ρ S.Gori 5/21
Measurement of the γ angle 1.5 e x c excluded area has CL > 0.95 l u d e d γ a t C L > 1.0 0 . m & m 9 ∆ ∆ 5 d s sin 2 β 0.5 ∆ m The CKM angle γ is the least known constraint: d ε α K γ β η 0.0 α V α Direct γ measurement Indirect γ extrapolation ub -0.5 ε γ K -1.0 CKM sol. w/ cos 2 β < 0 f i t t e r ICHEP 16 (excl. at CL > 0.95) -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 LHCb expected precision by 2029 (end of Run 4) < 0.4º ρ Most precise LHCb-CONF-2017-004 γ can be measured using tree level B decays measurement from (only CKM angle accessible at tree level) 1 experiment only Require interference between b → cW and b → uW to access it: M. Kenzie S.Gori 5/21
Theory for the γ angle γ is known very well in the SM second-order electroweak corrections (other theory errors can eliminated using data) Brod, Zupan, 1308.5663 γ is an good probe of new physics For example, for ∆ C 1 Im( ∆ C 1 ) and Im( ∆ C 2 ) can be of order ±10% without violating any constraints from data (constraints from B → D π and B → D ( ∗ )0 h 0 decays, b → d γ , B → ππ , ρπ , ρρ -decays). New physics in C 1,2 can cause sizeable shifts in γ (| δγ | ≈ 4º) Brod et al., 1412.1446 S.Gori 6/21
2. The physics of meson mixing
CP violation in the meson system Let us consider a meson (M) decay. We define the decay amplitudes to the final state f The mass eigenstates are In general, there are 3 types of CP violation: CP violation in mixing , when the two neutral mass eigenstate admixtures cannot be chosen to be CP-eigenstates CP violation in decay , when the amplitude for a decay and its CP-conjugate process have different magnitudes CP violation in the interference 0 of decays with and without mixing, which occurs in decays into final states that are common to and S.Gori 7/21
Example for the B s meson system B mesons b → s , b → d Mass eigenstates Flavor eigenstates can be affected by NP small number in the SM Interference between mixing and decay S.Gori 8/21
Latest measurements, B mesons B mesons B s b → s, b → d B d LHCb dominates this world average LHCb is comparable to Belle & Babar (latest LHCb (2017): 0.760 ± 0.034) S.Gori 9/21
Latest measurements, D mesons D mesons c → u In the SM, CP violating effects in the D0D0 system are expected to be small, O(10 -3 ) sizeable uncertainties on hadronic form factors cc production ~ 20 bb production at LHCb! Latest determination: LHCb, 5.0 fb -1 recorded in 2011-2016 PHYSICAL REVIEW D 97, 031101 through the decays * Cabibbo- Cabibbo-favored Cabibbo-favored suppressed that follows from the oscillation (“wrong sign” (WS) decay) (“right sign” (RS) decay) (also past determination through the decays to Kaons and pions) * S.Gori 10/21
Latest measurements, D mesons D mesons c → u In the SM, CP violating effects in the D0D0 system are expected to be small, O(10 -3 ) sizeable uncertainties on hadronic form factors cc production ~ 20 bb production at LHCb! Latest determination: LHCb, 5.0 fb -1 recorded in 2011-2016 PHYSICAL REVIEW D 97, 031101 through the decays * Cabibbo- Cabibbo-favored Cabibbo-favored suppressed that follows from the oscillation (“wrong sign” (WS) decay) (“right sign” (RS) decay) (also past determination through the decays to Kaons and pions) * non-vanishing difference between R D+ and R D- would imply CP violation No evidence for CP violation (68.3% CL.) in charm mixing is yet observed S.Gori 10/21
Probing high New Physics scales In the framework of effective field theories… Kamenik, 2014 present future Altmannshofer, 2017 CP violation in D mixing gives the best bound after ε K (Kaon mixing) S.Gori 11/21
Probing high New Physics scales In the framework of effective field theories… Kamenik, 2014 present future Altmannshofer, 2017 O(LHC direct) O(LHC direct) CP violation in D mixing gives the best bound after ε K (Kaon mixing) S.Gori 11/21
New CPV Higgs bosons (MFV 2HDM) Beyond EFTs, one can set constraints on the (flavor and) CP structure of NP models containing new (~ light) degrees of freedom Example: a 2HDM with Minimal Flavor Violation (MFV) CP violating S.Gori 12/21
New CPV Higgs bosons (MFV 2HDM) Beyond EFTs, one can set constraints on the (flavor and) CP structure of NP models containing new (~ light) degrees of freedom Example: a 2HDM with Minimal Flavor Violation (MFV) CP violating Buras, Carlucci, SG, Generically, Isidori, 1005.5310 O(1) complex coefficients Matrix element for meson mixing: ~2 σ bound S.Gori 12/21
New CPV Higgs bosons (flavorful 2HDM) Beyond EFTs, one can set constraints on the (flavor and) CP structure of NP models containing new (~ light) degrees of freedom MFV is not the full story for 2HDMs A “flavorful” 2HDM Altmannshofer, SG, Kagan, Silvestrini, Zupan, 1507.07927 (analogous structure in the down-quark sector) S.Gori 13/21
New CPV Higgs bosons (flavorful 2HDM) Beyond EFTs, one can set constraints on the (flavor and) CP structure of NP models containing new (~ light) degrees of freedom MFV is not the full story for 2HDMs A “flavorful” 2HDM Altmannshofer, SG, Kagan, Silvestrini, Zupan, 1507.07927 * * * * * * * O(1) complex coefficients (analogous structure in the down-quark sector) Altmannshofer, SG, Robinson, Tuckler, Approximate 1712.01847 U(2) symmetry in each sector 2 of the phases S.Gori 13/21
Complementarity with LHC searches Broad program for searches for new Higgs bosons Most searches (and interpretation of searches) are performed in the context of “type-II-like” 2Higgs doublet models. The typical golden channel is . This is not necessarily true in these new models The LHC tests the absolute value of the free parameters of the theory S.Gori 14/21
Complementarity with LHC searches Broad program for searches for new Higgs bosons Most searches (and interpretation of searches) are performed in the context of “type-II-like” 2Higgs doublet models. The typical golden channel is . This is not necessarily true in these new models MFV exclusion from SG, Haber, Santos, 1703.05873 The LHC tests the absolute value of the free parameters of the theory S.Gori 14/21
Complementarity with LHC searches Broad program for searches for new Higgs bosons Most searches (and interpretation of searches) are performed in the context of “type-II-like” 2Higgs doublet models. The typical golden channel is . This is not necessarily true in these new models Flavorful MFV exclusion from Altmannshofer, Eby, SG, Lotito, Martone, Tuckler, 1610.02398 SG, Haber, Santos, 1703.05873 The LHC tests the absolute value of the free parameters of the theory S.Gori 14/21
New CPV Higgs bosons (SUSY) SUSY Higgs sectors do not bring new sources of flavor violation at the tree level. Nevertheless, many new (Higgs) sources of flavor and CP violation (soft masses, trilinear terms) For example in the squark down sector: off-diagonal soft masses & trilinear terms 6X6 matrix S.Gori 15/21
New CPV Higgs bosons (SUSY) SUSY Higgs sectors do not bring new sources of flavor violation at the tree level. Nevertheless, many new (Higgs) sources of flavor and CP violation (soft masses, trilinear terms) For example in the squark down sector: off-diagonal soft masses & trilinear terms 6X6 matrix Example diagram: S.Gori 15/21 Altmannshofer, Buras, SG, Paradisi, Straub, 0909.1333
3. Kaon rare decays
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