yeo woong yoon (konkuk univ.) 2015/6/2, 16 th lhc meeting @ kias based on 1505.00291 in...

HEAVY HIGGS RESO-NANCE DIP PART I- FORMALISM

Yeo Woong Yoon (Konkuk Univ.)

2015/6/2, 16th LHC meeting @ KIAS

Based on 1505.00291

In collaboration with

Jeonghyeon Song(Konkuk Univ.), Sunghoon Jung (KIAS)

2

INTERLUDE - RESONANCE

𝑑�̂�= 12𝑠|ℳ𝑝𝑟𝑜𝑑|

2| 1

𝑝2−𝑀 2+𝑖𝑀 Γ |2

|ℳ𝑑𝑒𝑐|2𝑑𝜙𝐶𝐷

| 1

𝑝2−𝑀 2+𝑖𝑀 Γ |2

≅ 𝜋𝑀 Γ

𝛿(𝑝2−𝑀 2)

Using the Narrow Width Approximation (NWA)

: The area is

Production • BW2 • Decay

𝜎 ( 𝐴𝐵→Φ→𝐶𝐷 )=𝜎𝑝𝑟𝑜𝑑 ⋅Br

Φ

𝐵

𝐴 𝐶

𝐷

3

E598, PRL (1974), SLAC, PRL (1974)

Very excited moment in particle physics was when we discover a resonance peak for a new particle

h0

𝐽 /Ψ( Γ𝑀=3. 0×10− 5)

( Γ𝑀=3.4×10−5)

ATLAS, PLB (2012), CMS, PLB (2012)

What if th

e interference

effect is stro

ng?

4

HEAVY HIGGS SEARCH STRATEGY

2𝑚𝑡

and are promising

dominant region

Small tanbeta region Higgs Production rate is huge Largely con-strained by and 𝜏𝜏

Allmost 100% decay into for small tanbeta. reso-nance search is available from 500 GeV. Small tanbeta region is constrained by search.

Large tanbeta region Bottom and lepton Yukawa couplings are much in-hanced. Constrained by . 𝜏𝜏

Desert region. Currently, no experimental search for this region is avail-able.

Perturbaive is broken

Interference effect is important

Sizable decay width

For aligned 2HDM

Interference, one of the most striking phenomena in Quantum Mechanics..

ELECTRON GUN

Roger Bach et al, New Journal of Physics (2013)

1 2

5

At the LHC

CONTINUUM RESONANCE

Invariant Mass Distribution

DipNothingPeakPeak-Dip

?

6

7

GENERAL FORMALISM FOR THE INTERFERENCE EFFECT

8

CONTINUUM RESONANCE

9

BW-Res. Imaginary-partInterference

Real-partInterference

10

Interference effectively change

WHAT DOES IT AFFECT PHENOMENOLOGY?

Mainly..

1. Resonance shape changes

2. NWA should be modified

Also we need to consider following subtleties.

• Kinematic distribution of final state may be changed• Smearing effect might be significant

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1. RESONANCE SHAPE

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Real-Part Interference ()

1. RESONANCE SHAPE

We meet this case for the 125GeV SM Higgs production with diphoton decay channel

No complex phase in the resonance signalComplex phase in continuum affect beginning at 2loop

Dixon, Siu (2003) PRL

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1. RESONANCE SHAPE

After Gaussian smearing

Real-part Interference is pure odd function:

Interference only S. Martin (2012) PRD

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1. RESONANCE SHAPE

S. Martin (2012) PRD

* The Interference effect is quite small mainly due to the smalldecay width ().

Res. signal onlyRes. signal + Interference

Slight shift (150 MeV)of mass peak

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1. RESONANCE SHAPEImaginary-Part Interference ()

“Pure Dip”

BW-shape is preserved

(1+ 2𝑤𝑅

𝑠𝜙)<0

Pure Dip prefers sizable width and small R value (small signal to bg ratio).

𝜙=−90∘ ,𝑤𝑅

=0.7

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1. RESONANCE SHAPEImaginary-Part Interference ()

BW-shape is preserved

(1+ 2𝑤𝑅

𝑠𝜙)=0

“Nothing-ness”

𝜙=−90∘ ,𝑤𝑅

=0.5

17

1. RESONANCE SHAPEImaginary-Part Interference ()

BW-shape is preserved

(1+ 2𝑤𝑅

𝑠𝜙)>0

𝜙=𝜋2,

“Pure Peak”

𝜙=−𝜋2,𝑤𝑅

<0.5

: enhanced

: suppressed

𝜙=90∘ ,𝑤𝑅

=0.4

𝜙=−90∘ ,𝑤𝑅

=0.4

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2. MODIFIED NWA

Transient Estimated by NWA

𝐶=(1+ 2𝑤𝑅

𝑠𝜙)

We propose modified NWA as

𝜎 ⋅Br ∙𝐶

Correction factor, and simple measure of resonance shape

Cross section for production and decays :

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PREVIOUS DISCUSSIONS ON

INTERFERENCE EFFECT1. Photon collider study

Asakawa, Kamoshita, Sugamoto, Watanabe (2000) EPJC

Dixon, Sofianatos (2009) PRD

Niezurawski, Zarnecki, Krawczyk (2002) JHEP

Morris, Truong, Zappala (1994) PLB

Continuum bg is tree-level, Res. signal is loop level, so R is naturally loop suppressed. Dips can arise

Morris, Truong, Zappala (1994) PLB

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PREVIOUS DISCUSSIONS ON

INTERFERENCE EFFECT2. Hadron collider study

Dicus, Willenbrock, (1988) PRD

Glover, Bij (1989) NPB, Kauer, Brien 1502.04113

Campbell, Ellis, Williams (2011) JHEP

Both Res. signal and continuum are loop processes. R is order 1 (quite big) Small Im-part Interference Mostly peak (excess)

Campbell, Ellis, Williams (2011) JHEP

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𝑔𝑔→𝐴 /𝐻→𝛾𝛾

Sizable C factor. Mostly peak shape

Nothingness

Pure Peak

Pure PeakFor aligned 2HDM

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SUMMARYVery simple and powerful parametrization for the in-

terference effect and resonance shape.

Heavy Higgs search with must be a Dip (or deficit) search.

Even nothingness can happen in which Higgs can hide.

Modified NWA: The correction factor must be included for the interference effect.

Detailed resonance shape analyses of ,, Z, , - working in progress