Higgs and Dark Matter
Yeong Gyun Kim (GNUE)
The World’s largest acceler-ator
Over 3000 scientists from 38 coun-tries are taking part in ATLAS alone
A 16 page paper of CMS
More than 10 pages for author list
Integrated luminosity 2010-2012
503-14-2013 Moriond QCD 2013
Fundamental Questions• What are the most basic building
blocks of the universe?• How do they interact with each
other?
원자 가설 (atomic hypothesis)모든 물질은 원자로 이루어져 있으며 , 이들은 영원히 운동을 계속하는 작은 입자이다 .
John Dalton1766-1844
원자론은 존 돌턴에의해 부활되었다 .그는 모든 물질이 원자로구성되어있다는가정하에 화학반응을성공적으로 설명하였다 .
Richard Phillips Feynman (1918–1988)
다음 세대에 물려줄 과학적 지식을단 한 문장으로 요약해야 한다면 ,그것은 ‘원자가설’일 것이다 .
E. Rutherford
금박실험을 통한 원자핵 발견 (1911)양성자 발견 (1919)
J.J. Thomson
음극선 실험을 통한전자의 발견 (1897)
The Nobel prize in 1906
The Nobel prize in 1908
러더포드의 원자모형
J. Chadwick
중성자 발견 (1932)
The Nobel prize in 1935“for the discovery of the neutron”
원자핵은 양성자와 중성자로 이루어져 있다
양성자 중성자
그 후 , ‘ 양성자와 중성자는 쿼크로 이루어져 있다’는 것이 밝혀진다
SLAC 연구소의 물리학자들이양성자 내부에 있는 쿼크에대한 최초의 증거를 발견했다(1968)
The Nobel prize in 1990
Friedman Kendall Taylor
원자핵 붕괴과정에서 생성되는 전자의 에너지가연속적인 분포를 갖는 것이 관측됨
N. Bohr
에너지 , 운동량이 보존되지 않는가 ?
W. Pauli
새로운 가벼운 중성입자가 필요한가 ?(1930)
중성미자 (neutrino) 의 발견 (Cowan and Reines, 1956)
Fred Reines The Nobel prize in 1995“for the detection of the neutrino”
(observation of inverse beta decay)
Standard Model Particles
& Higgs boson
God(damn) Particle• In the Standard Model, particle interactions are
dictated by a local gauge symmetry SU(3)c x SU(2)L x U(1)Y.
• Electroweak gauge symmetry is broken sponta-neously by the vacuum value of a scalar (Higgs) field, giving masses to weak gauge bosons and matter particles.
• This implies the existence of a new scalar particle (Higgs particle, aka God particle).
Higgs at the LHC
Higgs at the LHC• The most important SM Higgs boson
production processes at the LHC
The SM Higgs production cross section at 7 TeV
The SM Higgs branching ratio
For mH = 125 GeV,
BR(h bb) ~ 58 %BR(h WW*) ~ 21.6 %BR(h ZZ*) ~ 2.7 %BR(h ττ) ~ 6.4 %BR(h γγ) ~ 0.22 %BR(h gg) ~ 8.5 %
Search Channels for Higgs
For All production mode
For WH/ZH production
Leptons/Photons essential for any search
ATLAS at Moriond 2013
CMS at Moriond 2013
Higgs at Moriond 2013
CMS at HCP 2012
Global Fit to Higgs data
Best fit converged towardsthe SM; in particular datanow disfavor the solution with c < 0 which appearedin previous fits and gave anenhanced h γ γ
Giardino et al. arXiv:1303.3570
Invisible Higgs Decays
A universal reductionof the rates in all decaychannel
Severely constrained byGlobal fits
Giardino et al. arXiv:1303.3570
Invisible Higgs Decays
Galactic Rotation Curves
중력렌즈효과를 통한 은하단 질량분석
An image of the cluster Abell 2218(taken with the Hubble space telescope)
Cosmic Microwave Background Anisotropies
,
,.
Brayon
Matter
Totaletc
WMAP satellite
Dark Matter Halo
Dark Matter in a galaxy surroundsthe visible matterin a halo.
It might be detectedthrough various ways.
Direct Detection• Dark Matter particles in the halo might
be detected by its elastic scattering with terrestrial nuclear target.
Indirect Detection• Neutrino Telescopes (e.g IceCube)
High Energy Neutrinos from DM annihilation at the core of SUN can be detected, via ν μ conversion
Indirect Detection• Search for DM annihilation into
gamma rays, antiparticles (antipro-ton, positron)
Positron Excess
Positron Excess• Pulsars remain the best explanation
of PAMELA/Fermi excess
• Dark Matter Explanations are tough- Large rates into e+e-- Low rates into antiprotons- But, viable scenarios exist
A Gamma-ray Line• Positrons are too messy• The observation of gamma-ray line in the
cosmic-ray fluxes would be a smoking-gun signature for dark matter annihilation in the universe
• Weniger found such gamma-ray signatures in the data of Fermi-LAT
A Gamma-ray Line
A Gamma-ray Line
DM production at CollidersLarge Missing Energy (+ jets, leptons etc)
The Higgs Portal
A Singlet Scalar DM• Silveira & Zee (85); McDonald (94); Burgess, Pospelov, ter Veldhuis
(00)
- A real scalar S, singlet under the SM gauge group- S -S symmetry, No <S> vacuum expectation value
S stable and neutral- Couplings to all SM fields are controlled by single pa-
rameter λ
Relic Density
DM annihilation cross sectiondepends on λ and ms
Relic density constraint requiresλ ~ O(0.1) and significantlysuppressed near Higgs pole
The connection between λ and ms derived from the density constraintis very predictive
Direct Detection
DM scattering with nuclei is given by t-channel Higgs exchange
Low DM mass region is ruled outby XENON100 constraint
A region with very light scalar(mS < 10 GeV) still not yet excludedby the precision of XENON100 due to its high threshold
Collider Signatures
R =
Over most of parameter space λ ~ O(0.1)
Higgs production might frequently be associated with S production, potentially leading to strong missing energy signals
A region with very light scalar (mS < 10 GeV) corresponds tovery large invisible branching ratio
A Singlet Scalar DM
arXiv: 1112.3299 Djouadi, Levedev, Mambrini and Quevil-lon
A Singlet Scalar DM• Provide definite predictions for DM-proton
scattering cross section and invisible Higgs decay rates, when thermal DM relic den-sity constraint imposed
• Low DM mass region (mS <100 GeV) is dis-favored by XENON100 experiment and LHC discovery of SM-like Higgs, except Higgs pole region
A Singlet Fermionic DM• YGK & Lee (07); YGK, Lee & Shin (08); Baek, Ko & Park
(11); Lopez-Honorez, Schwetz & Zupan (12)
Hidden sector
Connection between hiddenand SM sectors
A Singlet Fermionic DM• The scalar (Higgs) potential develops nontrivial vacuum expecta-
tion values for SM Higgs and singlet scalar
• The neutral scalar fields h and s are mixed, and the correspond-ing mass eigenstates h1 and h2 are given by
• Mixing between h and s makes the physical Higgs boson h1 and h2 have reduced couplings with the SM fermions and the SM weak gauge bosons
Direct Detection
mh1 = 120 GeVmh2 = 500 GeV
If mΨ < mh2,Direct detectionconstraint excludesmost of parameterspace, except Higgspole region
YGK, Lee & Shin (2008)
Direct Detection
mh1 = 120 GeVmh2 = 100 GeV
If mΨ~mh2 (or mΨ>mh2)large parameter spaces,which gives small DM-proton scattering crosssection below XENON100 limit, are allowed
YGK, Lee & Shin (2008)
Secluded DM• If singlet-like Higgs mass mh2 is less than or simi-
lar to DM mass, dominant contribution for DM an-nihilation arises from the following process
Singlet-like Higgs doesn’t decayto DM pair since it’s not kinematicallyallowed, but it decays entirely to SMparticles
This fixes essentially the coupling gs,while leaving the Higgs mixing angle θUnconstrained
Since the direct detection cross sectionis proportional to sin2(2θ), essentially any value below the XENON boundcan be obtained
Light Fermionic DMYGK & Shin (2009)
Direct Detection (mh2 < mΨ)Parameter choices giving rise toa relic density in the WMAP rangein the Higgs portal model withmh1 = 125 GeV.
Green and red points correspondto mh2 < mΨ with a more (r1 >0.9)or less (r1 < 0.9) SM Higgs-like h1,respectively.
The r1 > 0.9 requirement tends tokeep the scattering cross sectionbelow the XENON100 limit.
(signal strength reduction factor)
Lopez-Honorez, Schwetz & Zupan(2012)
Conclusions• Identified two simple ways to make thermal ferminonic DM consistent
with a SM-like Higgs at 125 GeV and XENON100 bounds
- Resonant Higgs portal. If the DM mass is close to half of the Higgs mass, then the annihilation cross section is enhanced by an s-channel reso-nance, allowing small couplings and a suppressed direct detection cross section.
- Indirect Higgs portal. If the mediator Ф is lighter than the DM, the relic density can be obtained by ΨΨ→ФФ annihilation, where the diagrams are independent of the Higgs portal strength. The Higgs portal only acts indirectly to provide thermal contact between the dark and the visible sector thermal baths.
• In all cases it is possible to have a SM-like Higgs, with an LHC signal strength modifier r1 > 0.9 (where r1 =1 corresponds to the SM Higgs).
Large Hadron Collider
God(damn) Particle• In the Standard Model, particle interactions are
dictated by a local gauge symmetry SU(3)c x SU(2)L x U(1)Y.
• Electroweak gauge symmetry is broken sponta-neously by the vacuum value of a scalar (Higgs) field, giving masses to weak gauge bosons and matter particles.
• This implies the existence of a new scalar particle (Higgs particle, aka God particle).
CMS at HCP 2012
CMS at HCP 2012
CMS at HCP 2012