Dimuon asymmetry and electroweak precision with Z

Transcription

1 Dimuon asymmetry and electroweak precision with Z Seodong Shin Seoul National University, Seoul, Korea TeV 2011, 20 May 2011 Work in progress with H.D. Kim and R. Dermisek

2 Outline Introduction : Same charge dimuon asymmetry by D0 New CP violation source in a Z model Electroweak precision with Z Conclusions

3 Busy days with news from Tevatron Reason of this workshop!! Lots of 2-3σ deviations... Top forward-backward asymmetry Dijet excess : single lepton + missing minv ET Boosted top, Multi-b events... Same charge dimuon asymmetry from D0 (1 year ago)

4 Some anomalies can be washed out... Underestimated SM effects Re-analysis of the data Change in the calibrations Such research already exist...

5 A new neutral gauge boson Z??? Many papers exist to explain the CDF results : Today s talks!!!!! Z from SU(6)XSU(2) GUT arxiv: by Jihn E. Kim and Seodong Shin No leptophobic Z from GUT E6 Z to explain the dimuon asymmetry from D0 Phys. Rev. D 83, (2010) [arxiv: ] by Jihn E. Kim, Min-Seok Seo and Seodong Shin arxiv: by A.K. Alok, S. Baek and D. London

6 Same-charge dimuon asymmetry in D0 Asymmetry in semi-leptonic decays of Bs,d meson A b s = N ++ N N ++ + N N++ : # of events μ+μ+ N : # of events μ μ As 0 : CP from mixing D arxiv: PR D fb ¹ A b s = (9.52 ± 2.51 ± 1.46) σ deviation from the SM value A bsm s =( ) 10 4 Additional CP violation source in Bs,d mixing

7 Obtain A b s from Bd mixing + Bs mixing a d s Γ(B d µ + X) Γ(B d µ X) Γ(B d µ + X) + Γ(B d µ X) a s s Γ(B s µ + X) Γ(B s µ X) Γ(B s µ + X) + Γ(B s µ X) where the relation at 1.96 TeV is A b s =(0.506 ± 0.043)a d s +(0.494 ± 0.043)a s s From the B factories a d s = (4.7 ± 4.6) 10 3 CDF result of 1.6 fb ¹ & direct measure (a s s) ave = (12.7 ± 5.0) 10 3 a s s by D0 2.5σ from a ssm s =(2.1 ± 0.6) 10 5

8 Bs,d - Bs,d mixing B 0 B 0 i d dt B 0 = M i Γ 2 B 0 M and Γ : 2 2 hermitian mass and decay matrices Mixing via off-shell (dispersive) intermediate states and on-shell (absorptive) intermediate states M q =2 M q 12 Γ q =2 Γ q 12 cos φ q φ q = Arg. M q 12 Γ q 12 φ SM d =( ) 10 2 φ SM s =( ) 10 3

9 a q s =ImΓq 12 M q 12 = Γq 12 M q 12 sin φ q = Γ q M q tan φ q M s = ± 0.10(stat.) ± 0.07(sys.) ps 1 = (11.7 ± 0.07 ± 0.05) GeV CDF measurement 1.6 fb ¹ With Γ s s, SM 12 =Γ only even with sin φ 12 s =1 It is impossible to obtain the central value of (a s s) ave For convenience, let s define Γ q NP 12 Γ q SM 12 h q e i2 σ q, M q NP 12 M q SM 12 h q e i2σ q

10 New CP violation source from Z Tree level mixing : M₁₂ What about Γ₁₂? Remind that ( bs)( ττ) V,A is safe from various exp. C.W.Bauer and N.D. Dunn, arxiv: Br.( B s τ + τ ) < 5% Br.( B X s τ + τ ) < 5% Not so severe constraints O(1) h s

11 h s 0.3 for every σ s h s < 2.5 for some σ s hs 1 is safely obtained (With the constraints of Ms, s, sinφs ) Z of a non-anomalous extra U(1) gauge symmetry can be obtained when the U(1) charge is assigned to be flavor non-universal in left-handed quarks. Possible to construct a model not violating the present constraints such as b s and Bs μ+μ

12 Mass of Z boson? Couplings? In general, assume (g sb) L,R : Z s L,R b L,R (g ττ ) L,R : Z τ L,R τ L,R With (gsb)l only h s = ρ sb 2 L ρ sb L = (g sb ) L g M Z M Z h s ρ sb L V cb M Z M Z (gττ ) L +(g ττ ) R g 2 Upper limit Fixed as 0.04 M Z M Z g ττ lower limit

13 Even in the case (g ττ ) L =(g ττ ) R and MZ = MZ Large coupling Perturbativity problem? Heavier Z increases the coupling allowed by the asymmetry

14 What happens if we consider g bb g ee and? Constraints from mesons such as decay Constraints of the Electroweak Precision data from LEP and SLC Explain some discrepancies in the Z-pole observables by Z with the above couplings PRL (2000) by J. Erler and P. Langacker PLB (1995) by F. Caravaglios and G.G. Ross arxiv: by R. Dermisek, S.G. Kim and A. Raval Case MZ MZ

15 Z pole observables Quantity Value Standard Model Pull Dev. M Z [GeV] ± ± Γ Z [GeV] ± ± Γ(had) [GeV] ± ± Γ(inv) [MeV] ± ± 0.07 Γ(l + l )[MeV] ± ± σ had [nb] ± ± R e ± ± R µ ± ± R τ ± ± R b ± ± R c ± ± A (0,e) FB ± ± A (0,µ) FB ± A (0,τ) FB ± A (0,b) FB ± ± A (0,c) FB ± ± A (0,s) FB ± ± s 2 l (A(0,q) FB ) ± ± ± A e ± ± ± ± A µ ± A τ ± ± A b ± ± A c ± ± A s ± ± Pull : Free input of mh Dev. : input of = 117 GeV mh With MZ MZ Strong constraint Explain these LR-asymmetry for hadronic final states

16 Goal : Explain the same-charge dimuon asymmetry and the EW precision data simultaneously with Z With g sb g ττ g bb g ee Upper bound by EW precision?

17 Conclusions Additional neutral gauge boson Z is being focussed on due to several Tevatron results The same-charge dimuon asymmetry can be also explained by Z We will see if the dimuon asymmetry and the EW precision data can be simultaneously explained by a Z model

18 Thank you