New opportunities on diboson

Transcription

1 New opportunities on diboson Marc Riembau IFAE/DESY 8 November 2017 Based on ongoing work with Christophe Grojean and Marc Montull Marc Riembau (IFAE/DESY) 8 November / 25

2 It seems that there is a mass gap between the SM states and the BSM states, so their effect can be encoded in an EFT L = L SM + i c i Λ 2 O(6) i +... D µ H σ i D ν HW i µν (D µ W µν ) 2 H 2 G µν G µν H 2 ( µ H) 2 f γ µ fh D µ H Already nailed by LEP H 2 H f f Only job of the LHC Marc Riembau (IFAE/DESY) 8 November / 25

3 Lepton colliders are for precision, hadron machines for discovery Marc Riembau (IFAE/DESY) 8 November / 25

4 This paradigm has been proven wrong on both sides One particularly interesting way in which it is wrong is that Energy beats accuracy Farina et.al. 16 Marc Riembau (IFAE/DESY) 8 November / 25

5 -If a deformation gets enhanced at high energy σ σ SM ( 1 + c E 2 /Λ 2 ) 0.1% precision on σ at E 200GeV 10% precision on σ at E 2TeV -Previous example, (D µ W µν ) & (D µ B µν ) induce E 2 growth in Drell-Yann -In this talk, we will focus on diboson. Marc Riembau (IFAE/DESY) 8 November / 25

6 Diboson in the SM M γ = i e2 sin θ 2m 2 W s Q f M Z = i e2 sin θ 2m 2 W s (T 3 sw 2 f sw 2 Q f ) M t = +i e2 sin θ 2m 2 W s 2s 2 W Sum does not grow with energy, as expected. However, it is obvious that a generic deviation from the SM relation will be amplified at large energies. Marc Riembau (IFAE/DESY) 8 November / 25

7 LHC diboson analyses LEP2 : δg z 1 = ± 0.031, δκ γ = ± 0.061, λ γ = ± LHC : δg z 1 = ± 0.008, δκ γ = ± 0.028, λ γ = ± Marc Riembau (IFAE/DESY) 8 November / 25

8 This high energy behaviour is whylhc has surpassed LEP bounds on atgc, with % on δκ γ, δg 1z and λ γ. However, this means that LHC is reaching the precision at which Z-pole measurements bounded the Zf f vertices. e.g. M(RR; 00) = i e 2 sinθ 2m 2 W s2 W We will study diboson including atgcs together with vertex corrections δg Zu L s [ ] δg Zq R + (δκ γ δκ z )Q f sw 2 + O(s 0 ) δg 1z, δκ γ, λ γ, δg Zu R, δg Zd L, δg Zd R Corrections to W vertices not independent: δg Wq = δg Zu L δg Zd L. Marc Riembau (IFAE/DESY) 8 November / 25

9 LEP anomalous vertices Model independent bounds on Z coupling to light flavours really bad: Must reconstruct the charge of the jets to distinguish up- from down-quarks, and quarks from antiquarks for the asymmetries: δg Zu R Zu δgl δgl Zd 5%, δgr Zd 15% But being agnostic in flavour is not a good attitude in life: if c ij Λ 2 f i γ µ f j H D µ H offdiagonal c s must be insanely tuned if Λ few TeV. Marc Riembau (IFAE/DESY) 8 November / 25

10 LEP anomalous vertices a) MFV: SU(3) 5 kills offdiagonal corrections and relates different families, e.g. δg Zu δg Zu δg Zd δg Zd ( [δgr Zu ] ij = A + B m ) i δ ij, m 3 L = ± R = ± L = ± R = ± b) Flavour universal: δg Zu δg Zu δg Zd δg Zd L = ± R = ± L = ± R = ± O(m k /m 3 V ik V kj ) for L , ρ = [δgr Zu ] ij = A δ ij , ρ = Efrati et al 15 Marc Riembau (IFAE/DESY) 8 November / 25

11 Process q L q L W ± T Z T q L q L W ± L Z L ū L u L W + T W T d L d L W + T W T ū L u L W + L W L d L d L W + L W L ū R u R W + L W L d L d R W + L W L Higgs basis +λ γ δgl Zu + δgl Zd δg 1z +λ γ λ γ δgl Zd δg 1z δκ γ δgl Zu 0.43δg 1z δκ γ δgr Zu 0.15δg 1z δκ γ δg 1z 0.10δκ γ δg Zd R (Notice accidentally small coefficients for TGCs) We want to perform a global study to answer two questions: 1) Do nonzero Zff affect LHC atgc constraints? 2) Does diboson give us any information on Zff couplings? Marc Riembau (IFAE/DESY) 8 November / 25

12 LHC diboson analyses We did an analisis taking into account several dilepton searches at 7, 8 and 13TeV Detector L[fb 1 ] s Process Obs. Ref. ATLAS 4.6 7TeV WW lνlν p (1) T l ATLAS TeV WW lνlν p (1) T l CMS TeV WW lνlν m ll ATLAS TeV WZ lνll p TZ CMS TeV WZ lνll p TZ ATLAS TeV WZ lνll m WZ ATLAS-CONF Cross check with ATLAS/CMS is ok, e.g. 20 B (WW ATLAS 8TeV) 10 B (WW ATLAS 8TeV) 10 B (WW ATLAS 8TeV) fw 5 fwww 0 fwww fb fb fw Marc Riembau (IFAE/DESY) 8 November / 25

13 Constraints on atgcs Global 7 parameter fit on diboson data has flat directions: δg 1 Z solid: δg Zq LR profiled dashed: δg Zq LR =0 pp WW,WZ (7,8,13TeV) 68%/95% CL δκγ δg R Zu δg R Zu =t W δκγ pp WW,WZ (7,8,13TeV) solid: δg Zq LR profiled δκγ δg L Zu solid: atgc profiled dashed: atgc=0 pp WW,WZ (7,8,13TeV) 68%/95% CL Zu δg R Global fit to diboson / Exclusive fit When including vertex corrections, LHC data cannot fit the TGCs due to flat directions. Must include LEP constraints on Zff vertices. χ 2 = χ 2 diboson + χ2 LEP Marc Riembau (IFAE/DESY) 8 November / 25

14 Constraints on atgcs - diboson, anomalous Zff=0 - diboson, anomalous Zff=MFV - diboson, anomalous Zff=FU Marc Riembau (IFAE/DESY) 8 November / 25

15 Constraints on atgcs Important to remark that there are no model independent fits. Even here, hidden assumptions: L ie δκ γ W + µ W ν A µν + i e m 2 W λ γ W + µνw νρa ρµ Induces magnetic dipole moment δκ γ + λ γ and electric quadrupole δκ γ λ γ, and both must arise at loop level for minimally coupled theories. δκ γ δg 1z λ γ δg 1z 1 16π 2 Profiling over δκ λ and λ γ assumes to be comparable to δg 1z. For a large class of theories, can be set to zero. Marc Riembau (IFAE/DESY) 8 November / 25

16 Constraints on atgcs Marc Riembau (IFAE/DESY) 8 November / 25

17 anomalous Zf LHC diboson only, LEP MFV, LEP FU, Combination Marc Riembau (IFAE/DESY) 8 November / 25

18 A glimpse to the future It is interesting to investigate the capabilities of a HL-LHC phase Number of events with mll>m ll CUT /fb 1000/fb 300/fb pp e + μ - Nevents /fb m ll CUT -We used the m ll observable of pp lνlν channel. -Naive rescaling of the 8 and 13TeV systematics: 15% and 30% in the overflow bin. As a dramatic case, we consider 30%/60%. -The 15%/30% approximately reproduces the ATLAS projections for the TGCs. Marc Riembau (IFAE/DESY) 8 November / 25

19 A glimpse to the future 95%CL for LEP and pp lνlν 13TeV at 3/fb 0.02 dashed: 30%/60% LEP MFV LEP FU solid : 15%/30% 95%CL for LEP and pp lνlν 13TeV at 3/fb 0.02 dashed: 30%/60% LEP MFV LEP FU solid : 15%/30% δg R Zd 0.00 δg R Zu atgc profiled δκγ=λγ=0 δg 1 z=δκγ=λγ= Zd δg L atgc profiled δκγ=λγ=0 δg 1 z=δκγ=λγ= Zu δg L Marc Riembau (IFAE/DESY) 8 November / 25

20 A glimpse to the future δg 1 Z %CL; pp WW lνlν s =13TeV at 3ab -1 δg Zq LR =0 δg Zq LR =LEP(MFV) solid: σ syst=15%/30% dashed: σ syst=30%/60% δκγ λγ %CL; pp WW lνlν s =13TeV at 3ab -1 δg Zq LR =0 δg Zq LR =LEP(MFV) solid: σ syst=15%/30% dashed: σ syst=30%/60% δg 1 Z λγ %CL; pp WW lνlν s =13TeV at 3ab -1 δg Zq LR =0 δg Zq LR =LEP(MFV) solid: σ syst=15%/30% dashed: σ syst=30%/60% δκγ Marc Riembau (IFAE/DESY) 8 November / 25

21 Interpretation LHC sets bounds %. This means that is probing scales δg Zu c v 2 Λ 2 Λ/ c 2TeV For c 1, Λ 2TeV and E/Λ 1 thus the EFT expansion makes sense. At the same time, σ σ SM 1 + c 6 g SM E 2 Λ 2 + ( c2 6 g 2 SM + c 8 ) E 4 g SM Λ 4 We are sensitive to c 2 6 terms. To neglect dimension 8 terms, if c 8 c 6, we require c 6 g SM. Currently, E Λ guarantees c 2 6 g SMc 8. This also means that we are only testing strongly coupled theories. Marc Riembau (IFAE/DESY) 8 November / 25

22 Interpretation A simple toy model: vector custodial triplets L µ, R µ L int = L a µ + R 0 µ + [ γ H g Jµ Ha g + γ V Jµ a + g F [ δ H g Jµ H g + δ V g J µ + F 1 2 (δ H g R + µ J H µ + h.c.) γ F g J Fa µ δ F g J F µ ] ] Biektter et al Marc Riembau (IFAE/DESY) 8 November / 25

23 Interpretation Assuming m E, one can integrate out the heavy vectors and match with the EFT: δg 1z = g 2 + g 2 g 2 [ 2 mw chw g 2 m 2 16π g 2 g 2 (g 2 γ H γ V + g 2 δ H δ V ) +... δκ γ = g 2 2 mw 16π 2 m 2 (c HW + c HB ) λ γ = 6g 2 2 mw 16π 2 m 2 c 3W δg Zu mw 2 g 2 [ L = m 2 g 2 γ H γ Q + g 2 ( g 2 +γ Q γ V 2 g 2 ) 3 g 2 g 2 (γ H γ V + δ H δ V ) + O( g 4 ] g 4 ) δg Zd L =... Even the simplest model leads to a hierarchy of couplings: δg Zu,d L,R : δg 1z : δκ γ : λ γ g 2 g 2 : 1 : g 2 16π 2 : g 2 16π 2 for 4π g g, realization of previous assumptions: ] δg Zu,d L,R δg 1z δκ γ λ γ Marc Riembau (IFAE/DESY) 8 November / 25

24 Interpretation Complementarity among different physics: dijets (g δ Q) 2 m 2 e.g., composite q L, g = 4π,, higgs (g δ H) 2 m 2, diboson g 2 δ Q δ H m 2 dijets : m δ Q 40TeV higgs : m δ Q 8TeV dijets + higgs : m 2 δ Q δ H (18TeV ) 2 diboson : m 2 δ Qδ H (14TeV ) 2, δ Q δ H < 0 δ Q δ H (20TeV ) 2, δ Q δ H > 0 Marc Riembau (IFAE/DESY) 8 November / 25

25 Conclusions - Diboson offers a window to precision physics at LHC - Current diboson data can be used to improve some LEP Z-pole constraints. - In the future, not including the vertex corrections in diboson analyses will not be an option. Huge impact on TGCs and potential improvement with respect LEP. Marc Riembau (IFAE/DESY) 8 November / 25