SLIDE 11 Model ¡independent ¡coupling ¡extracRon ¡
Sandro ¡De ¡Cecco ¡-‑ ¡LPNHE ¡Paris ¡ 11 ¡
σvis = σ prod×BR(H → f ) σ prod gHi
2
and BR(H → f )= Γ f Γtot gHf
2
Γtot σvis gHi
2 gHf 2
Γtot(gHj, j =1…n)
In general, σ is a complicated ILC: need to measure Γtot in addition to absolute BR´s to extract couplings in a model-independent way
12*
ModelZindependent*determinaEons*of** Higgs*couplings*
ExampleZZconsider*the*following*four*independent** measurements:*
Y1 =σZH = F1 · g2
HZZ
Y2 =σZH × Br(H → b¯ b) = F2 · g2
HZZg2 Hb¯ b
ΓT Y3 =σν¯
νH × Br(H → b¯
b) = F3 · g2
HW W g2 Hb¯ b
ΓT Y4 =σν¯
νH × Br(H → WW ∗) = F4 · g4 HW W
ΓT
ΓT is the Higgs total width, gHZZ, gHWW, and gHb¯
b are
the Higgs couplings to ZZ, WW, and b¯ b, respectively, and F1, F2, F3, F4 are calculable quantities. For example, F2 = ✓ σZH g2
HZZ
◆ ✓ΓH→b¯
b
g2
Hb¯ b
◆ . The couplings are obtained as follows:
⇐ ⇒ gHZZ
⇐ ⇒ gHWW
⇐ ⇒ ΓT
- 4. From gHZZ, gHWW, ΓT and Y2 or Y3
⇐ ⇒ gHb¯
b
Model-independent Global Fit for Couplings
33 σxBR measurements (Yi) and σZH (Y34,35)
χ2 =
35
X
i=1
✓Yi − Y 0
i
∆Yi ◆2
nlock the
◆ ✓
HW W
◆ ✓
Htt
◆
g, gHττ, gHγγ, gHµµ, gHtt, Γ0
- It is the recoil mass measurement that is the key to unlock
✓
HZZ
◆
gHZZ, gHW W , gHbb, gHcc, gHgg, g
10 free parameters:
In ¡reality ¡: ¡