Date post: | 17-Jan-2016 |
Category: |
Documents |
Upload: | edwina-wade |
View: | 214 times |
Download: | 1 times |
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
11
1. RESONANCE SHAPE
12
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
13
1. RESONANCE SHAPE
After Gaussian smearing
Real-part Interference is pure odd function:
Interference only S. Martin (2012) PRD
14
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
15
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
16
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
18
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 :
19
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
20
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
21
𝑔𝑔→𝐴 /𝐻→𝛾𝛾
Sizable C factor. Mostly peak shape
Nothingness
Pure Peak
Pure PeakFor aligned 2HDM
22
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