Searches in b s ll ll Decays DPF , August, 2017 1 Physics - PowerPoint PPT Presentation

S. Stone New Physics Searches in b → s ll ll Decays DPF , August, 2017 1

Physics rationale n Finding New Particles, arising from New Forces is the goal of High Energy Physics n Motivated by: dark matter, hierarchy problem, particle masses, origin of CKM elements n ATLAS & CMS can detect these directly n LHCb & other flavor physics experiments (Belle II, BES III, DUNE, Muon g-2, µ to e conversion) do this indirectly DPF , August, 2017 2

Effects on M W from quantum loops n FP probes large mass scales via virtual quantum loops. An example, of the importance of such loops are changes in the W mass q M w changes due to m t dM W α m t dm t M w q M w changes due to m H dM W α − dm H dm H M H Gave predictions of m H prior to discovery DPF , August, 2017 3

Lepton flavor universality n In the SM differences between interactions of individual charged leptons can only be due to their masses, which leads to precise predictions n m τ /m µ /m e : 3477 / 207 / 1 n Seemed prudent to makes some tests n Hiller & Kruger suggest order ~10% effects from some NP models ( hep-ph/0310219) DPF , August, 2017 4

Penguin decays n NP may be seen easier in suppressed processes such as penguin decays n SM diagrams: n New particles can appear, augmenting SM ones n Next: experimental tests DPF , August, 2017 5

q 2 = m 2 ( µ + µ - ) b → h µ + µ – d B /dq 2 - LHCb x10 -6 n Data generally below model predictions at low q 2 DPF , August, 2017 6

CMS K* µ + µ – d B /dq 2 � n Same for CMS, good agreement with LHCb, note different models LHCb data DPF , August, 2017 7

B - → K - l + l - B B − → K − µ + µ − n ( ) R K ≡ B B − → K − e + e − ( ) + 0.090 ± 0.036 n LHCb R K = 0.745 − 0.074 for 1<q 2 <6 GeV 2 , 2.6 σ from SM. Actually measure B B − → K − µ + µ − ) / B B − → K − J / ψ , J / ψ → µ + µ − ( ( ) the double ratio: R K ≡ B B − → K − e + e − ) / B B − → K − J / ψ , J / ψ → e + e − ( ( ) n Measured B for Kee J/ ψ Not J/ ψ , 1<q 2 <6 agrees with GeV 2 SM prediction DPF , August, 2017 8

B 0 → K * 0 l + l - n SM expectations B B 0 → K *0 µ + µ − ( ) photon pole R K * ≡ B B 0 → K *0 e + e − ( ) d Γ /dq 2 Also measured as a double ratio Long distance n LHCb data contributions from cc states above arXiv:1705.05802 threshold n + 0.110 ± 0.024, 0.045 < q 2 < 1.1 R K * = 0.660 − 0.070 n + 0.113 ± 0.047,1.1 < q 2 < 6.0 R K * = 0.685 − 0.069 n Each ~2.4 σ from SM DPF , August, 2017 9

B 0 → K * 0 e + e - n Invariant mass spectra, J/ ψ shape is used to model signal arXiv:1705.05802 DPF , August, 2017 10

Angular observables in K* µ + µ – � From Justine Serrano DPF , August, 2017 11

′ The curious case of P 5 n Most angular observables agree with SM n Deviation in P 5 ′ near q 2 =~6 GeV 2 DPF , August, 2017 12

Lepton universality test in P 5 ′ n Belle does both e’s & µ ’s (PRL 118, 111801, 2017) 2.6 σ from SM for µ mode, 1.1 σ for e mode DPF , August, 2017 13

Exp. references DPF , August, 2017 14

Effective Hamiltonian n Integrate out heavy degrees of freedom, then ⎛ 10 ⎞ SM = − G F ℓ + C 2 O 2 ℓ + , where C i ’s are * ℓ O i ℓ V tb V ts C 1 C i H eff ∑ O 1 ∑ ⎜ ⎟ ⎜ ⎟ 2 ⎝ ⎠ ℓ = e , µ i = 3 Wilson coeff. & O i are operators. Can use independent C i µ & C i e . O 1,2 : Current-current O 3,4,5,6 : QCD penguins n Different processes are O 7 : Electromagnetic penguin described by different O i O 8 : Chromo-magnetic penguin O 9,10 : Electroweak penguin n NP can appear in C i ’s n Also include inherently NP chirality flipped operators O 9 ′ & O 10 ′ as additional possibilities. n Allows for a model independent analysis DPF , August, 2017 15

Operators contributing to LFU ( ' ) = α EM ( ' ) = α EM n , ( ) ℓ γ µ ℓ ( ) ℓ γ µ γ 5 ℓ ( ) , ( ) s γ µ P s γ µ P O 9 L ( R ) b O 10 L ( R ) b 4 π 4 π where P L & P R are left & right handed projection operators n B (B s → µ + µ - ) provides a constraint on C 10 µ + C 10 µ ′ ; other constraints from B s mixing n K* longitudinal part of the rate is similar to K ll but with chirally flipped operators that interfere with reversed sign with the SM n As a consequence, different C i variations have different effects on R K & R K* DPF , August, 2017 16

Correlated variations in C i ’s n Parametric Geng et al., dependence of [arXiv:1704.05446] R K vs R K* allowing a single C i µ to vary (not C i e ) µ µ n Decreases in both R K & R K* µ can be explained µ by C 9 µ or C 10 µ , not C 9 ′ µ or C 10 ′ µ DPF , August, 2017 17

Example fits n Two separate fits Altmannshofer, Stangl & Straub [arXiv:1704.05435] q 1) LFU observables: R K , R K* , Re C 10 µ Contours for Δχ 2 =2.3, . Belle e- µ differences in angular 6.2 & 11.8 observables SM q 2) b → s µµ global fit observables: K* µµ B & angular, K µµ B , φ µµ B & angular, B (b → X s µµ ) from BaBar; dashed lines with Re ʹ C 9 µ . hadronic uncertainties x5 SM Contours n Here ReC 9(10) µ is diff wrt SM. for Δχ 2 =2.3, 6.2 & 11.8 Prefers ReC 9 µ ~-1, (SM is 0) DPF , August, 2017 18

Should we believe LFU violation? No, not yet Yes n R measurements are double n Statistics are marginal in ratio’s to J/ ψ , check with each measurement K*J/ ψ → e + e - / µ + µ - n Need confirming evidence =1.043±0.006±0.045 in other experiments for R K n B (B - → K - e + e - ) agrees with & R K* SM prediction puts onus on n Disturbing that R K* is not muon mode which is well ~1 in lowest q 2 bin, which it measured and low should be, because of the n Both R K & R K* are different photon pole than ~1 n Angular distribution n Supporting evidence of evidence can be effected effects in angular by hadronic uncertainties distributions DPF , August, 2017 19

R D ( * ) = B (B → D ( * ) τν )/ B (B → D ( * ) µ ν ) See Siddi’s talk SM τ mode is difficult to measure as there are at least 2 missing neutrinos DPF , August, 2017 20

Conclusions n We may be seeing the first hints of physics beyond the SM in a failure of lepton flavor universality n This implies lepton flavor violation, e.g. may be able to see B - → K - τ ± µ ∓ (Glashow, Guadagnoli & Lane arXiv:1411.0565) n Viable models include: q Z ′ : not just a heavy Z, different couplings, e.g. Z ′→ bs q Leptoquarks Can these be seen in direct production at the LHC? DPF , August, 2017 21

The End The End DPF , August, 2017 22

Backup slides DPF , August, 2017 23

B → X s ℓ + ℓ - n Define two q 2 regions: low 1-6, high >14.4 GeV 2 n Low again probes C 7 , while high C 9 & C 10 n Data Belle BaBar Only 140/fb? Only 82/fb? n High q 2 : B (B → X s ℓ + ℓ - )=(4.3±1.2)x10 -7 , SM 2.3x10 -7 n Low q 2 : B (B → X s ℓ + ℓ - )=(1.63±0.50)x10 -6 , SM 1.59x10 -7 n B o → K* o ℓ + ℓ - , is also sensitive to C 7 at low q 2 , C 9 & C 10 at high q 2 DPF , August, 2017 24

Kee mass distributions DPF , August, 2017 25

R K* DPF , August, 2017 26

Another fit n arXiv:1704.05446 DPF , August, 2017 27

Seeking New Physics n Flavor Physics as a tool for NP discovery q The main purpose of FP is to find and/or define the properties of physics beyond the Standard Model (SM) q FP probes large mass scales via virtual quantum loops. An example, of the importance of such loops is the Lamb shift in atomic hydrogen q A small difference in energy between 2S 1/2 & 2P 1 /2 levels that should be of equal energy at lowest order DPF , August, 2017 28