flavor physics: lecture 2 Jure Zupan u. of cincinnati 13th Hadron Collider Physics Summer School 2018 , Aug 29 2018 � 1
review of lecture 1 • have looked at the flavor structure in the SM • experiments show it is predominantly due to Kobayashi-Maskawa mechnism J. Zupan Flavor physis: lecture 2 � 2 HCPSS, Aug 29 2018
outline lecture 2 • meson mixing (left-over from lecture 1) • searching for new physics • B physics anomalies • Higgs and flavor J. Zupan Flavor physis: lecture 2 � 3 HCPSS, Aug 29 2018
measurements • two types of measurements shown in the CKM triangle plot D 0 • tree level transitions u u c • less likely to be affected B − b u by new physics K − s • loop level transitions • more likely to be affected by new physics J. Zupan Flavor physics: lecture 2 � 4 HCPSS 2018, Aug 29 2018
measurements • two types of measurements shown in the CKM triangle plot D 0 • tree level transitions u u c • less likely to be affected B − b u by new physics K − s • loop level transitions • more likely to be affected by new physics J. Zupan Flavor physics: lecture 2 � 4 HCPSS 2018, Aug 29 2018
measuring beta J. Zupan Flavor physics: lecture 2 � 5 HCPSS 2018, Aug 29 2018
CP violation • 3 categories of CPV observables • CPV in the decay : interf. between oscill. decay amplitudes • CPV in mixing : interf. between M 12 and Γ 12 (different ways to oscillate B 0 ↔ B ̄ 0 ) • CPV in interference between decays with and without mixing J. Zupan Flavor physics: lecture 2 � 6 HCPSS 2018, Aug 29 2018
B meson mixing • for f that is a CP eigenstate, e.g., f=J/ ψ K S • time dependent CP asymmetry Γ (B 0 (t) → J/ ψ K S ) Γ (B ̄ 0 (t) → J/ ψ K S ) J. Zupan Flavor physics: lecture 2 � 7 HCPSS 2018, Aug 29 2018
B meson mixing • for f that is a CP eigenstate, e.g., f=J/ ψ K S • time dependent CP asymmetry Γ (B 0 (t) → J/ ψ K S ) Γ (B ̄ 0 (t) → J/ ψ K S ) J. Zupan Flavor physics: lecture 2 � 7 HCPSS 2018, Aug 29 2018
B meson mixing • for f that is a CP eigenstate, e.g., f=J/ ψ K S • time dependent CP asymmetry Belle, 1201.4643 Γ (B 0 (t) → J/ ψ K S ) Γ (B ̄ 0 (t) → J/ ψ K S ) J. Zupan Flavor physics: lecture 2 � 7 HCPSS 2018, Aug 29 2018
B meson mixing • S f measures CPV in interference between decays with and without mixing • C f is direct CPV asymmetry oscill. J. Zupan Flavor physics: lecture 2 � 8 HCPSS 2018, Aug 29 2018
B meson mixing • q/p is universal for all final states f • in the SM • for B → J/ ψ K S in the SM • so that the CPV parameter in the SM J. Zupan Flavor physics: lecture 2 � 9 HCPSS 2018, Aug 29 2018
the upshot • CPV an inherently quantum mechanical effect • governed by a phase in Lagrangian • KM mechanism the dominant origin of CPV • measurements point to a consistent picture • since ρ̄ ≲ η̄ the CKM weak phase is large, O(1) • tests will be significantly improved in the near future J. Zupan Flavor physics: Lecture 1 � 10 HCPSS 2018, Aug 28 2018
the future: tree processes @ belle 2 Charles et al, 1309.2293 J. Zupan Flavor physics: Lecture 1 � 11 HCPSS 2018, Aug 28 2018
the future: tree processes @ belle 2 Charles et al, 1309.2293 SM standard candle J. Zupan Flavor physics: Lecture 1 � 11 HCPSS 2018, Aug 28 2018
searching for new physics � 12
two ways of searching for bsm in flavor • measuring rare decays • e.g., b → sl + l - • measuring meson mixing amplitudes • e.g., B d -B ̄ d mixing J. Zupan The Mysteries of Flavor (I) � 13 SSI 2018, Aug 8 2018
two ways of searching for bsm in flavor • measuring rare decays • e.g., b → sl + l - • measuring meson mixing amplitudes • e.g., B d -B ̄ d mixing J. Zupan The Mysteries of Flavor (I) � 13 SSI 2018, Aug 8 2018
effective hamiltonian • effective hamiltonian for B mixing } 1.26 QCD corrections + loop function ( λ 3 ) 2 • for B s mixing instead ( λ 2 ) 2 J. Zupan The Mysteries of Flavor (I) � 14 SSI 2018, Aug 8 2018
new physics in mixing • measuring mixing amplitude precisely can probe for new physics • can parametrize the new physics contributions as J. Zupan Flavor physis: lecture 2 � 15 HCPSS, Aug 29 2018
bounds on new physics in mixing • ~20% corrections relative to the SM allowed at present • to be reduced to ~5% B 0 -B ̄ 0 B s -B ̄ s Charles et al, 1309.2293 ~now ~now J. Zupan Flavor physis: lecture 2 � 16 HCPSS, Aug 29 2018
bounds on new physics in mixing • ~20% corrections relative to the SM allowed at present • to be reduced to ~5% B 0 -B ̄ 0 B s -B ̄ s Charles et al, 1309.2293 ~in 10 years ~now ~in 10 years ~now J. Zupan Flavor physis: lecture 2 � 16 HCPSS, Aug 29 2018
what scale? • what does this mean in terms of bounds on NP masses? • assume for instance, that NP has the same (V-A)x(V-A) structure as the SM • e.g., could be due to Z' exchange • h d <20% correction to the SM gives, for C NP = 1 • the difference entirely due to V ts ≃ 5V td J. Zupan Flavor physis: lecture 2 � 17 HCPSS, Aug 29 2018
low energy precision bounds UTFit 0707.0636, 1411.7233 for latest charm see also Bazavov et al, 1706.04622 UTFit 0707.0636, 1411.7233 • an impressive 2007 → ~now progress on flavor bounds in last 10 years c ū b ̄ s • in D, B s mixing • also from ε K d ̄ s 1 Λ 2 (¯ b L γ µ d L )(¯ b L γ µ d L ) J. Zupan The Mysteries of Flavor (I) � 18 SSI 2018, Aug 8 2018
low energy precision bounds UTFit 0707.0636, 1411.7233 for latest charm see also Bazavov et al, 1706.04622 UTFit 0707.0636, 1411.7233 • an impressive 2007 → ~now progress on flavor bounds in last 10 years c ū b ̄ s • in D, B s mixing • also from ε K d ̄ s 1 Λ 2 (¯ b L γ µ d L )(¯ b L γ µ d L ) J. Zupan The Mysteries of Flavor (I) � 18 SSI 2018, Aug 8 2018
two ways of searching for bsm in flavor • measuring rare decays • e.g., b → sl + l - • measuring meson mixing amplitudes • e.g., B d -B ̄ d mixing J. Zupan Lecture 1: ... flavor physics � 19 ESHEP 2018, Jun 24 2018
present experimental situation • many different transitions measured • two sets of quark level transitions show ~4 σ deviations from the SM* b → sµ + µ − b → c τν Λ NP ∼ 3 TeV Λ NP ∼ 30 TeV * there are other interesting deviations, e.g., ~3 σ deviation in ε '/ ε , see, e.g., Buras et al, 1507.06345; RBC-UKQCD, 1502.00263 J. Zupan Flavor physics: lecture 2 � 20 HCPSS, Aug 29 2018
b → sµµ � 21
upshot • b → sll flavor anomaly • theoretically clean, ~4 σ excess • does it make sense from new physics perspective? • reasonable scale for NP models* *mostly face the I. I. Rabi's muon question: "Who ordered that?" J. Zupan Flavor physis: lecture 2 � 22 HCPSS, Aug 29 2018
experimental situation • b → sll : generated at 1-loop in the SM ↵ s L � µ b L ¯ G F V tb V ∗ 4 ⇡ C 9(10) ¯ `� µ ( � 5 ) ` ts • in the SM b → see the same as b → s μμ • Lepton Flavor Universality in the SM J. Zupan Flavor physis: lecture 2 � 23 HCPSS, Aug 29 2018
b → sll : experiment • three clean observables: R K and R K* two bins � R K = Br ( B → Kµµ ) � � Br ( B → Kee ) � [1 , 6]GeV 2 • 2.6 σ anomaly in R K Bordone, Isidori, Pattori, 1605.07633 R K = 1 . 00 ± 0 . 01 SM: R K = 0 . 745 ± 0 . 082 exp: LHCb,1406.6482 (3.0 fb -1 @7+8TeV) J. Zupan Flavor physis: lecture 2 � 24 HCPSS, Aug 29 2018
b → sll : experiment • 2 bins in R K* • 2.2-2.5 σ deviation in each experiment: LHCb, 1705.05802 (3.0 fb -1 @7+8TeV) LHCb, 1705.05802 J. Zupan Flavor physis: lecture 2 � 25 HCPSS, Aug 29 2018
global fits • in principle much more info • Br(B → K ( ∗ ) μμ ) , Br(B s → φμμ ) , Br(B → X s μμ ) • angular obs. in B 0 → K ∗ 0 μμ , B s → φμμ LHCb, 1403.8044 • sensitive to hadronic inputs S. Jager, May 2017 • require form factors predict. (QCD sum rules), charm loops, nonfactor. contribs. • prefer NP in muons J. Zupan Flavor physis: lecture 2 � 26 HCPSS, Aug 29 2018
Altmannshofer, Stangl, Straub, 1704.05435 global fits • in principle much more info • Br(B → K ( ∗ ) μμ ) , Br(B s → φμμ ) , Br(B → X s μμ ) • angular obs. in B 0 → K ∗ 0 μμ , B s → φμμ LHCb, 1403.8044 • sensitive to hadronic inputs S. Jager, May 2017 • require form factors predict. (QCD sum rules), charm loops, nonfactor. contribs. • prefer NP in muons J. Zupan Flavor physis: lecture 2 � 26 HCPSS, Aug 29 2018
what kind of NP? • from now on will assume that NP in b → s μμ • what is the NP scale? • the Wilson coeffs. in previous slide C INP ~O(1) • types of NP • tree level (heavy or light) • loop level J. Zupan Flavor physis: lecture 2 � 27 HCPSS, Aug 29 2018
Recommend
More recommend
