CP violation in h Z UMass Amherst May 2, 2015 Marco Farina - - PowerPoint PPT Presentation

▶
cp violation in
SMART_READER_LITE
LIVE PREVIEW

CP violation in h Z UMass Amherst May 2, 2015 Marco Farina - - PowerPoint PPT Presentation

Sep 06, 2022 32 likes •283 views

CP violation in h Z UMass Amherst May 2, 2015 Marco Farina Cornell University First look The Higgs looks quite SM like PDG Review (Nov 2013) Introduction How well at the end of LHC? Snowmass Higgs Working Group Report 1310.8361

slide-1
SLIDE 1

CP violation in h → Z ɣ

Marco Farina Cornell University

UMass Amherst May 2, 2015

slide-2
SLIDE 2

First look

The Higgs looks quite SM like

PDG Review (Nov 2013)

slide-3
SLIDE 3

Introduction

How well at the end of LHC?

Snowmass Higgs Working Group Report 1310.8361

slide-4
SLIDE 4

Introduction

How well at the end of LHC?

Snowmass Higgs Working Group Report 1310.8361

?

slide-5
SLIDE 5

FB asymmetry

  • Only one angle.

Claim: you can construct a FB asymmetry

  • Just Zɣ itself?
  • Interference with ɣɣ
  • HL-LHC might not be enough
  • A. K orchin, V. Kovalchuk 1303.0365
slide-6
SLIDE 6

FB asymmetry

  • Only one angle.

Claim: you can construct a FB asymmetry

  • Just Zɣ itself?
  • Interference with ɣɣ
  • HL-LHC might not be enough

Y Chen et al. 1405.6723

  • A. K orchin, V. Kovalchuk 1303.0365
slide-7
SLIDE 7

4 leptons

  • Intereference with ZZ
  • HL-LHC necessary

few % precision

  • How to disentangle

different effects? (not a smoking gun)

  • Y. Chen, R. Harnik, R. Vega-Morales 1404.1336
slide-8
SLIDE 8

4 leptons

  • Intereference with ZZ
  • HL-LHC necessary

(few % precision)

  • How to disentangle

different effects? (not a smoking gun)

  • Y. Chen, R. Harnik, R. Vega-Morales 1404.1336
slide-9
SLIDE 9

Lepton colliders?

Felix’s Presentation

slide-10
SLIDE 10

Lepton colliders?

Felix’s Presentation

slide-11
SLIDE 11

Converted photons?

  • Same idea of ɣɣ, photons converting to e+e- pairs
  • Even more challenging
  • F. Bishara et al. 1312.2955
slide-12
SLIDE 12

Our proposal

  • What else can you interefere with?
  • “QCD” Background!
  • Different set of Higgs couplings involved

MF, Y. Grossman, D. Robinson 1503.06470

slide-13
SLIDE 13

Interlude

It is a well known effect in the ɣɣ case

  • L. Dixon, MS. Siu hep-ph(0302233
  • S. Martin 1303.3342
slide-14
SLIDE 14

Interlude

  • L. Dixon, MS. Siu hep-ph(0302233
  • S. Martin 1303.3342

It is a well known effect in the ɣɣ case

slide-15
SLIDE 15

Kinematics

Back to Zɣ: 5 independent variables in a 2 → 3 process. 4 in our narrow width, on shell Z approximation

slide-16
SLIDE 16

Kinematics

Back to Zɣ: 5 independent variables in a 2 → 3 process. 4 in our narrow width, on shell Z approximation

slide-17
SLIDE 17

Kinematics

Under CP Back to Zɣ: 5 independent variables in a 2 → 3 process. 4 in our narrow width, on shell Z approximation

slide-18
SLIDE 18

Massaging

...

slide-19
SLIDE 19

Massaging

...

slide-20
SLIDE 20

Main result

How can we get the coefficients?

  • Do the full computation
  • Quick and painless: MCFM (custom)
slide-21
SLIDE 21

Fitting main result

How can we get the coefficients?

  • Do the full computation
  • Quick and painless: MCFM (custom)
slide-22
SLIDE 22

Doomed?

x 1 x 30

Very small effect O(1%)

slide-23
SLIDE 23

Doomed!

“Easy” observable SM (ξ=0) hypothesis rejection at 95% C.L. requires

x 1 x 30

slide-24
SLIDE 24

Future colliders?

  • One could use VBF at lepton colliders

(not competitive?)

  • What about a 100TeV collider?

x 1 x 30

slide-25
SLIDE 25

Conclusions

  • H → Zɣ is hard!
  • At least HL-LHC is mandatory: yet very challenging

measurements

  • Do we need better ideas?