Higgs and Dark Matter

Yeong Gyun Kim

(GNUE)

The World’s largest accelerator

Over 3000 scientists from 38 countries are taking part in ATLAS alone

A 16 page paper of CMS

More than 10 pages for author list

Integrated luminosity 2010-2012

5 03-14-2013 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 Dalton 1766-1844 원자론은 존 돌턴에 의해 부활되었다. 그는 모든 물질이 원자로 구성되어있다는 가정하에 화학반응을 성공적으로 설명하였다.

Richard Phillips Feynman (1918–1988)

다음 세대에 물려줄 과학적 지식을 단 한 문장으로 요약해야 한다면, 그것은 ‘원자가설’일 것이다.

E. Rutherford

금박실험을 통한 원자핵 발견 (1911) 양성자 발견 (1919)

J.J. Thomson

음극선 실험을 통한 전자의 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 물리학자들이 양성자 내부에 있는 쿼크에 대한 최초의 증거를 발견했다 (1968)

The Nobel prize in 1990

Friedman Kendall Taylor

원자핵 붕괴과정에서 생성되는 전자의 에너지가 연속적인 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 spontaneously 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 towards the SM; in particular data now disfavor the solution with c < 0 which appeared in previous fits and gave an enhanced h γ γ Giardino et al. arXiv:1303.3570

Invisible Higgs Decays

A universal reduction of the rates in all decay channel Severely constrained by Global 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 surrounds the visible matter in a halo. It might be detected through 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 (antiproton, 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 Colliders

Large 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 parameter λ

Relic Density

DM annihilation cross section depends on λ and ms

Relic density constraint requires λ ~ O(0.1) and significantly suppressed near Higgs pole The connection between λ and ms

derived from the density constraint is very predictive

Direct Detection

DM scattering with nuclei is given by t-channel Higgs exchange

Low DM mass region is ruled out by XENON100 constraint A region with very light scalar (mS < 10 GeV) still not yet excluded by 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 to very large invisible branching ratio

A Singlet Scalar DM

arXiv: 1112.3299 Djouadi, Levedev, Mambrini and Quevillon

A Singlet Scalar DM

• Provide definite predictions for DM-proton scattering cross section and invisible Higgs decay rates, when thermal DM relic density constraint imposed

• Low DM mass region (mS <100 GeV) is disfavored 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 hidden and SM sectors

A Singlet Fermionic DM

• The scalar (Higgs) potential develops nontrivial vacuum expectation values for SM Higgs and singlet scalar

• The neutral scalar fields h and s are mixed, and the corresponding 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 GeV mh2 = 500 GeV If mΨ < mh2, Direct detection constraint excludes most of parameter space, except Higgs pole region

YGK, Lee & Shin (2008)

Direct Detection

mh1 = 120 GeV mh2 = 100 GeV If mΨ~mh2 (or mΨ>mh2) large parameter spaces, which gives small DM- proton scattering cross section below XENON 100 limit, are allowed

YGK, Lee & Shin (2008)

Secluded DM

• If singlet-like Higgs mass mh2 is less than or similar to DM mass, dominant contribution for DM annihilation arises from the following process

Singlet-like Higgs doesn’t decay to DM pair since it’s not kinematically allowed, but it decays entirely to SM particles This fixes essentially the coupling gs, while leaving the Higgs mixing angle θ Unconstrained Since the direct detection cross section is proportional to sin2(2θ), essentially any value below the XENON bound can be obtained

Light Fermionic DM

YGK & Shin (2009)

Direct Detection (mh2 < mΨ)

Parameter choices giving rise to a relic density in the WMAP range in the Higgs portal model with mh1 = 125 GeV. Green and red points correspond to mh2 < mΨ with a more (r1 >0.9) or less (r1 < 0.9) SM Higgs-like h1, respectively. The r1 > 0.9 requirement tends to keep the scattering cross section below 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 resonance, 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 spontaneously 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