The Forward-Backward Top Asymmetry in a Singlet Extension of the MSSM

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1 The Forward-Backward Top Asymmetry in a Singlet Extension of the MSSM Alejandro de la Puente University of Notre Dame PASI 2012 University of Buenos Aires March 5, 2012 Based on JHEP 1202 (2012) 016 [arxiv: [hep-ph}]

2 MSSM W MSSM = µ H ˆ u Ĥ d + yu ij û c ˆ ih u ˆQ Lj y ij ˆd c d iĥd ˆQ Lj yτ ij ê c iĥd ÊLj What can it do: It can alleviate the amount of fine tuning that is present in the Standard Model Light Higgs mimics SM Higgs in production and decay Bound on light Higgs mass proportional to gauge couplings M h 0 M Z cos 2β Remaining Higgs can be arbitrarily large

3 A more natural solution to the LHP S-MSSM: W = W Y ukawa +(µ + λs)h u H d µ ss 2

4 A more natural solution to the LHP S-MSSM: W = W Y ukawa +(µ + λs)h u H d µ ss 2 The scalar potential of the S-MSSM V = (µ 2 + m 2 H u ) H u 2 +(µ 2 + m 2 H d ) H d 2 +(m 2 s + µ 2 s) S 2 +(B s S 2 + h.c.) + [(λµ s S + B µ + A λ λs)h u H d + λµs ( H u 2 + H d 2 )+h.c.] + λ 2 (H u H d )(H u H d ) + λ 2 S 2 ( H u 2 + H d 2 ) λ 2 A λ (g2 + g 2 )( H u 2 H d 2 ) g2 H uh d 2 m 2 s B s

5 In a nutshell... We are able to push the SM-like Higgs mass above the LEP bound for a wide range of µ s 1TeV, tan β 10 and m t 300 GeV In the large µ s limit, singlet cannot be seen at LHC, but we expect a lighter SUSY spectrum. Small µ s and unseen at LEP. limit, lightest states are mostly singlets

6 The Forward-Backward Top Asymmetry within the context of the S-MSSM CDF and D0 have reported a new measurement of the inclusive forward-backward top asymmetry A t t FB = ± ± (CDF with 5.3 fb 1 ), A t t FB = ± (DØ with 5.4 fb 1 ).

7 The Forward-Backward Top Asymmetry within the context of the S-MSSM CDF and D0 have reported a new measurement of the inclusive forward-backward top asymmetry A t t FB = ± ± (CDF with 5.3 fb 1 ), A t t FB = ± (DØ with 5.4 fb 1 ). The S-MSSM is extended by dimension-five operators in the superpotential in order to study their contributions to the asymmetry

8 A simple extension is given by: W = W S MSSM + Λ ij M Ŝ ˆ H u û c i ˆQ j Σ ij M ŜĤd ˆd c i ˆQ j. Allow for t-channel contributions to mediated by Higgs particles. q q scattering Scale M dictates where these operators arise.

9 A simple extension is given by: W = W S MSSM + Λ ij M Ŝ ˆ H u û c i ˆQ j Σ ij M ŜĤd ˆd c i ˆQ j. Assume a fermion basis where SM up-type Yukawa couplings are diagonal. Consider Λ = 0 0 Λ Λ We assume that Σ ij 0 since compared to effects, corrections arising from Σ are suppressed. Λ

10 For scalars/pseudoscalars, Lagrangian given by: L u,t i F i R,H H i if i R,AA i ūl t R + F i L,HH i + if i L,AA i ūr t L + h.c. where F i R,(H,A) = Λ 31 2M (v sin β O (H,A) i,s F i L,(H,A) = Λ 13 2M (v sin β O (H,A) i,s + v s O (H,A) i,h u ), + v s O (H,A) i,h u ) Additionally, for charged scalars: L d,t v s M Λ 31 cos β d L t R H + h.c

11 Asymmetry Define the total NP contribution to the differential cross section by: M NP total = M NP + M SM LO, NP INT Then, the asymmetry can be defined by: A total FB = A NP FB R + A SM FB (1 R) where A NP FB = σnp F σf NP A SM FB = σsm F σf SM R = σ NP B + σ NP B σ SM B + σ SM B σ NP total σ SM total + σnp total,,.

12 Constraints I u-t mass mixing: M 2 U = Λ13 v s v u 2 M v Λ13 s v u M mt,0 v Λ13 s v u M mt,0 v Λ31 s v u M 2 + m 2 t,0 Imposing that m u 3.1 MeV constraints the product Λ 13 Λ 31 Meson-mixing ( K 0 K 0 ): Λ = v s 2M Λ cos β 1 32π 2 TeV m H ± 2 i F (x i ) V Λ 2 1i V Λ 2 2i < 10 6 New top decay channels: Impose that Γ (t φ i u)= m t 32π Γ total 7.6 GeV 1 m2 φ i m 2 t 2 F i2 L + FR i2

13 Constraints II (Collider) Same sign-top production: g tt (Λ 13 Λ 31 ) 2 Single-top production: Recent D0 measurement: σ (p p tqb + X) =2.90 ± 0.59 pb g t g t t t u (a) H i,a i d H ± (b) Suppression of (b) by making either Λ 13 or Λ 31 small. Suppression of (a) a bit more trickier... Due to complexity of final states direct comparison with D0 measurement difficult to make

14 Small µ s limit: 11 For all curves µ s = 20 GeV and µ, B µ =0! (pp " tt) (pb) v s = 130 GeV v s = 20 GeV v s = 200 GeV v s = 300 GeV # 31 = 0 except for small v s where µ, B µ = 180, 500 GeV A FB

15 Small µ s limit: A FB v s = 20 GeV v s = 130 GeV For all curves µ s = 20 GeV and µ, B µ =0 except for small v s where µ, B µ =0, 500 GeV ! v s = 20 GeV v s = 130 GeV "(pp # tt) (pb) ! 31

16 Large µ s limit: Singlet decouples and only light scalar is SM-like Higgs. Coupling to up and top quarks proportional to (Λ 13,31 ) v sin β M O H 1,S µ s =1.5 TeV,µ= 500 GeV,A λ = 1. TeV and B µ = 500 GeV A FB ! 31 " (pp # tt) (pb) ! 31 Large tension between minimizing negative interference contributions to the cross section and obtaining a large asymmetry

17 Conclusions: S-MSSM provides a natural solution to the LHP. Can be extended to address recent results from Colliders. In this work we address the large forwardbackward top asymmetry reported by CDF and D0. Small µ s more promising with Λ couplings below 4π and regions where effective approach holds. Large µ s, needs both Λ 13, Λ 31. Constraints can be easily satisfied since v s is small. but... Cross section too large