CP violation in quark flavor physics

Transcription

1 CP violation in quark flavor physics Stefania Gori University of Cincinnati Testing CP-violation for baryogengesis University of Massachusetts, Amherst, March 29, 2018

2 Outline and aim of the talk Outline 1. Phases of the CKM unitary triangle 2. Meson mixing 3. Kaon rare decays Aims Overview Latest updates on the experimental measurements Implications on NP theories CP violation in: B mesons b s, b d D mesons c u Kaons s d During the rest of the workshop, we will learn its connection to baryogengesis 2/21

3 Standard Model flavor & CP (VCKM) ij Flavor and CP-violation arising from the CKM matrix (VCKM) 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 3/21

4 Its success excluded area has CL > γ excluded at CL > 0.95 m d & m s sin 2β 0.5 m d ε K α η 0.0 α γ β -0.5 V ub α -1.0 CKM f i t t e r ICHEP 16 γ ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) (68% CL) ρ Remarkable success of the CKM picture! 4/21

5 Measurement of the γ angle 1.5 excluded at CL > 0.95 excluded area has CL > γ & m s m d The CKM angle γ is the least known constraint: Direct γ measurement Indirect γ extrapolation η sin 2β ε K α V ub γ α β α m d -1.0 CKM f i t t e r ICHEP 16 γ ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) LHCb expected precision by 2029 (end of Run 4) < 0.4º ρ 5/21

6 Measurement of the γ angle 1.5 excluded at CL > 0.95 excluded area has CL > γ & m s m d The CKM angle γ is the least known constraint: Direct γ measurement Indirect γ extrapolation η sin 2β ε K α V ub γ α β α m d -1.0 CKM f i t t e r ICHEP 16 γ ε K sol. w/ cos 2β < 0 (excl. at CL > 0.95) LHCb expected precision by 2029 (end of Run 4) < 0.4º ρ γ can be measured using tree level B decays (only CKM angle accessible at tree level) Require interference between b cw and b uw to access it: LHCb-CONF Most precise measurement from 1 experiment only M. Kenzie 5/21

7 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, γ is an good probe of new physics For example, for C1 Im( C1) and Im( C2) can be of order ±10% without violating any constraints from data (constraints from B Dπ and B D ( )0 h 0 decays, b dγ, B ππ, ρπ, ρρ-decays). New physics in C1,2 can cause sizeable shifts in γ ( δγ 4º) Brod et al., /21

8 2. The physics of meson mixing

9 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 of decays with and without mixing, which occurs in decays into final states that are common to and 0 7/21

10 Example for the Bs meson system B mesons b s, b d Flavor eigenstates Mass eigenstates can be affected by NP small number in the SM Interference between mixing and decay 8/21

11 Latest measurements, B mesons Bs B mesons b s, b d Bd LHCb dominates this world average LHCb is comparable to Belle & Babar (latest LHCb (2017): ± 0.034) 9/21

12 Latest measurements, D mesons 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 * * Cabibbo-favored that follows from the oscillation through the decays Cabibbosuppressed ( wrong sign (WS) decay) (also past determination through the decays to Kaons and pions) Cabibbo-favored D mesons c u PHYSICAL REVIEW D 97, ( right sign (RS) decay) 10/21

13 Latest measurements, D mesons 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 * * Cabibbo-favored that follows from the oscillation through the decays Cabibbosuppressed ( wrong sign (WS) decay) (also past determination through the decays to Kaons and pions) Cabibbo-favored D mesons c u PHYSICAL REVIEW D 97, ( right sign (RS) decay) non-vanishing difference between RD + and RD - would imply CP violation No evidence for CP violation in charm mixing is yet observed (68.3% CL.) 10/21

14 Probing high New Physics scales Kamenik, 2014 In the framework of effective field theories present future Altmannshofer, 2017 CP violation in D mixing gives the best bound after εk (Kaon mixing) 11/21

15 Probing high New Physics scales Kamenik, 2014 In the framework of effective field theories O(LHC direct) present future Altmannshofer, 2017 CP violation in D mixing gives the best bound after εk (Kaon mixing) O(LHC direct) 11/21

16 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 12/21

17 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 Generically, O(1) complex coefficients Buras, Carlucci, SG, Isidori, Matrix element for meson mixing: ~2σ bound 12/21

18 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, (analogous structure in the down-quark sector) 13/21

19 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, * * * * * * * O(1) complex coefficients (analogous structure in the down-quark sector) Approximate U(2) symmetry in each sector 2 of the phases Altmannshofer, SG, Robinson, Tuckler, /21

20 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 14/21

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, The LHC tests the absolute value of the free parameters of the theory 14/21

22 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 Flavorful exclusion from SG, Haber, Santos, Altmannshofer, Eby, SG, Lotito, Martone, Tuckler, The LHC tests the absolute value of the free parameters of the theory 14/21

23 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: 6X6 matrix off-diagonal soft masses & trilinear terms 15/21

24 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: 6X6 matrix off-diagonal soft masses & trilinear terms Example diagram: Altmannshofer, Buras, SG, Paradisi, Straub, /21

25 3. Kaon rare decays

26 Kaon rare decays in the SM Kaons s d Very clean decays (mainly short distance contribution) Dominant uncertainties originate from the CKM parameters Vcb, Vub and γ. Only operator in the SM Buras, Buttazzo, Girbach-Noe, Knegjens, box diagrams 16/21

27 Kaon rare decays in the SM Kaons s d Very clean decays (mainly short distance contribution) Dominant uncertainties originate from the CKM parameters Vcb, Vub and γ. Only operator in the SM CP-conserving Long-distance contributions Buras, Buttazzo, Girbach-Noe, Knegjens, CP-violating Very rare! Access to NP + box diagrams Brod, Gorbahn, Stamou ; Buras, Buttazzo, Girbach-Noe, Knegjens, NA62 and KOTO are beginning their experimental program 16/21

28 News from NA62 (K + ) Kaons s d Predecessor: NA62 has started data taking in Sept BNL measurement, 2009 (4 BNL-949; 3 BNL-787) CERN-SPSC Exploratory analysis with 5% of 2016 data set 0 signal event found Moriond 2018 Talk by Marchevski 400 GeV SPS protons Kaon pion neutrinos 17/21

29 News from NA62 (K + ) Kaons s d Predecessor: NA62 has started data taking in Sept BNL measurement, 2009 (4 BNL-949; 3 BNL-787) CERN-SPSC Exploratory analysis with 5% of 2016 data set 0 signal event found Moriond 2018 Talk by Marchevski Analysis of the full 2016 data announced at Moriond Optimized to suppress backgrounds from leading Kaon decay modes 400 GeV SPS protons Kaon pion neutrinos 1 event seen! (0.3 expected) Data taking until the end of 2018 Running after 2018 is approved Aim: Measurement of the SM BR at the ~10% level 17/21

30 News from KOTO (KL) Kaons s d Predecessor: Indirect bound: (using Grossmann-Nir) Grossman-Nir bound (model independent): KEK E391a bound, 2010 (0 events seen) Moriond 2018 Talk by Marchevski Experimental challenges associated to the signature (2 photons+nothing) 18/21

31 Predecessor: Indirect bound: (using Grossmann-Nir) News from KOTO (KL) Grossman-Nir bound (model independent): KEK E391a bound, 2010 (0 events seen) Kaons s d Moriond 2018 Talk by Marchevski Experimental challenges associated to the signature (2 photons+nothing) initial physics data taken in 2013 ( ) 1 event observed (0.34 expected) hermetic veto 2015 run: ~ 20 times more data Preliminary analysis discussed at Moriond (still to be optimized) expectation: improvement on the bound by a factor of ~10 Final Aim: 10% measurement of the BR 18/21

32 CKM fit from Kaon measurements! Putting together future NA62 and KOTO analyses, one can reconstruct the unitary triangle (just using Kaon physics) Kaons s d 3 constraint on the BR 10% measurement with 10% measurement 19/21

33 Implications on New Physics theories Many NP models induce sizable NP effects in the BRs: Custodial Randall-Sundrum [Blanke, Buras, Duling, Gemmler, SG, ] Simplified Z, Z' models [Buras, Buttazzo, Knegjens, ] Lepton flavor universality violation models [Bordone, et al., ] v sl,r dl,r Kaons s d 20/21

34 Implications on New Physics theories Many NP models induce sizable NP effects in the BRs: Custodial Randall-Sundrum [Blanke, Buras, Duling, Gemmler, SG, ] Simplified Z, Z' models [Buras, Buttazzo, Knegjens, ] Lepton flavor universality violation models [Bordone, et al., ] sl,r dl,r Kaons s d At the operator level: Buras, Buttazzo, Knegjens, SM operator Region for Minimal Flavor Violating models 20/21

35 Conclusions & Outlook Interesting times for flavor / CPV physics Plethora of new data in the last few years and even more data to come (LHCb, BelleII, NA62, KOTO, ) Complementarity between different systems b s, b d, c u, s d to test the flavor and CP structure of nature 21/21