Rare decays at LHCb. Jibo HE/ 何吉波 (UCAS), for the LHCb collabora=on Presented at CCNU

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1 Jibo HE/ 何吉波 (UCAS), for the LHCb collabora=on Presented at CCNU

2 Introduc=on Flavor-Changing Neutral Current (FCNC) process suppressed in SM. New Physics? Described by effec=ve Hamiltonion Jibo HE (UCAS) 2

3 The LHCb experiment Dedicated to precision study of b/c-hadrons Jibo HE (UCAS) 3

4 Very rare decays B (s) ->μ + μ -, B (s) ->τ + τ -, B (s) ->μ + μ - μ + μ - Lepton flavor viola=on B (s) ->e + μ -, τ + ->μ + μ - μ + Electroweak penguin B->K (*) μ + μ -, Λ b ->μ + μ - pk - (π), LFU (see G. Wormser s talk) Radia=ve B s àφγ, B->Kππγ Rare charm, covered by L. Sun Rare Strange K S ->μ + μ - Jibo HE (UCAS) 4

5 B (s) ->μ + μ - Road to B (s) ->l + l -... Jibo HE (UCAS) 5

6 B (s) ->μ + μ -, latest results from LHCb [PRL 118 (2017) ] With 4.6 k -1 of data, first observa=on of B s ->μ + μ - from a single experiment 7.8σ LHCb alone Jibo HE (UCAS) 6

7 B s ->μ + μ - effec=ve life=me B s mixing => effec=ve τ [PRL 118 (2017) ] A ΔΓ =1 in SM First measurement, not yet sensi=ve to A ΔΓ [De Bruyn et. al., PRL 109 (2012) ] Jibo HE (UCAS) 7

8 B (s) ->τ + τ - B (s) ->τ + τ - not helicity suppressed in SM, predicted BR ~200 higher than B (s) ->μ + μ - BR(B s ->τ + τ - ) enhanced by NP scenarios, previously best limit given by Babar [Babar, PRL 96 (2006) ] Jibo HE (UCAS) 8

9 B (s) ->τ + τ - Using τà3πν (a 1 ) mode Normalized to BàD + D s [PRL 118 (2017) ] Jibo HE (UCAS) 9

10 B(s) + + ->μ μ μ μ [JHEP 03 (2017) 001] Non-resonant BR(Bs->4μ)~ , can be enhanced in, e.g., MSSM (P, S sgolds=no) Upper CL: Jibo HE (UCAS) 10

11 B (s) ->e + μ - [arxiv: ] LFV forbidden in SM. Observa=on of LFV? clear sign of NP! Normalized to B 0 ->K + π -, and B + ->J/ψK + Best upper limits so far: Jibo HE (UCAS) w/o Brem w/ Brem 11

12 B 0 àk *0 μ + μ - Rates and angular distribu=ons sensi=ve to NP Jibo HE (UCAS) 12

13 B 0 àk *0 μ + μ - : P 5 LHCb updated with 3 k -1, anomaly s=ll there Also measured by Belle, ATLAS, CMS [LHCb, JHEP 02 (2016) 104] [Belle, PRL 118 (2017) ] [ATLAS-CONF ] [CMS, arxiv: ] Jibo HE (UCAS) 13

14 Observa=on of Λ b ->pkμ + μ - [JHEP 06 (2017) 108] Also measured CP asymmetry Jibo HE (UCAS) 14

15 Observa=on of Λ b ->pπμ + μ - Measured BR w.r.t. Λ b ->pπj/ψ(μ + μ - ) [JHEP 04 (2017) 029] Jibo HE (UCAS) 15

16 [PRD 95 (2017) (R)] Search for + + B->K χ(μ μ ) Search for the long-lived scalar par=cle χ in the hidden sector Jibo HE (UCAS) 16

17 [PRD 95 (2017) (R)] Search for B->K + χ(μ + μ - ) (cont.) Parameter space of the infla=on model [B. Batell, et. al., PRD 83 (2011) ] [F. Bezrukov et. al., JHEP 05 (2010) 010, JHEP 07 (2013) 140] Jibo HE (UCAS) 17

18 Photon polariza=on in B s àφγ [PRL 118 (2017) ] Photons in b->sγ mainly le-handed Time-dependent signal rate with 24.8k 4.1k Jibo HE (UCAS) 18

19 Photon polariza=on in B s àφγ Ra=o between B 0 /B s as t [PRL 118 (2017) ] Compa=ble with SM in 2σ Jibo HE (UCAS) 19

20 K S ->μ + μ - [EPJC 77 (2017) 678] SM predic=on: BR=(5.0±1.5) 10-12, can be enhanced up to factor 100 K S ->π + π - : control channel, main Bkg Previous limit Jibo HE (UCAS) 20

21 The LHCb upgrades Jibo HE (UCAS) 21

22 LHCb sta=s=cs-=meline LHCb prospects Jibo HE (UCAS) 22

23 Aer the upgrade B (s) ->μ + μ - B 0 àk *0 μ + μ - Jibo HE (UCAS) 23

24 Summary LHCb performed the world-leading measurements of rare decays: Very rare decays, e.g., B (s) ->μ + μ -, B (s) ->τ + τ - LFV, e.g., B (s) ->e + μ - Electroweak penguin, e.g., B->K (*) μ + μ - Radia=ve, e.g., B s àφγ Rare Strange, e.g., K S ->μ + μ - Run-II data-taking ongoing well, upgrade(s) under its way, stay tuned! Jibo HE (UCAS) 24