recent atlas higgs results and koria

Recent ATLAS Higgs Results and KoRIA2nd AKPA Physics Symposium

January 20, 2012Dr. Jaehoon Yu

Outline

• What is High Energy Physics?• Where are we at present with Higgs?• What have we seen in Higgs at the LHC?• What can we do with KoRIA?• Conclusions

Jan. 20, 2012 ATLAS Higgs, HEP and KoRIA Dr. Jaehoon Yu

High Energy Physics• Definition: A field of physics that pursues understanding

the fundamental constituents of matter and basic principles of interactions between them.

• Known interactions (forces):– Gravitational– Electro-Weak– Strong

• Current theory: The Standard Model of Particle Physics– Unified Weak and Electromagnetic: SU(2)xU(1)– Strong Interaction: SU(3)– Currently:SU(3)xSU(2)xU(1)– Meaning: 8+4 mediators for forces

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The Standard Model of Particle Physics • Prescribes the following fundamental structure:

• Three families of leptons and quarks together with 12 force mediators Simple and elegant!!!

• Tested to a precision of 1 part per million!

~0.1mp

Family

Discovered in 1995, ~175mp

Directly observed in 2000

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Good, but still lots we don’t know…• Why are there three families of quarks and leptons?• Why is the mass range so large (0.1mp – 175 mp)?• How do matters acquire mass?

– Higgs mechanism but where is the Higgs, the God particle?• Why is the matter in the universe made only of particles?

– What happened to anti-particles? Or anti-matters?• Why are there only three apparent forces?• Is the picture we present the real thing?

– What makes up the 96% of the universe?– How about extra-dimensions?

• How is the universe created? • Are there any other theories that describe the universe better?

– Does the super-symmetry exist?

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Fermilab Tevatron and LHC at CERN• World’s Highest Energy proton-anti-proton collider

– 4km circumference– Ecm=1.96 TeV (=6.3x10-7J/p 13M Joules on the

area smaller than 10-4m2)– Equivalent to the kinetic energy of a 20t truck at the

speed 81mi/hr 130km/hr• ~100,000 times the energy density at the ground 0 of the

Hiroshima atom bomb– Was shut down at 2pm CDT, Sept. 30, 2011

• Other parts of the complex is still running!!

Chicago

Tevatron p

p CDF DØ

• World’s Highest Energy p-p collider– 27km circumference, 100m underground– Design Ecm=14 TeV (=44x10-7J/p 362M

Joules on the area smaller than 10-4m2) Equivalent to the kinetic energy of a B727

(80tons) at the speed 193mi/hr 312km/hr ~3M times the energy density at the ground 0 of the

Hiroshima atom bomb• First 7TeV collisions on 3/30/10 The highest energy

humans ever achieved!!• First collisions in 2012 in mid March, 2012

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ATLAS Higgs, HEP and KoRIA Dr. Jaehoon Yu

ATLAS Detector

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• Weighs 7000 tons and 10 story tall• Can inspect 1,000,000,000 collisions/second• Records 200 – 400 collisions/second• Records approximately 350,000,000 bytes/second• Record 2x1015 (2,000,000,000,000,000) bytes each year (2

PetaByte). 200*Printed material of the US Lib. of Congress

Jan. 20, 2012


7

ATLAS Integrated Luminosity in 2011

LHC delivered 2010 - 2011: 5615 pb-1

ATLAS recorded 2010 - 2011: 5252pb-1

ATLAS data taking ε: 94%About 160 times the data taken in 2010!!1700pb-1 in one month!! 2012 expects close to 10,000pb-1


Pixel module

Cooling pipe

Cables

C-fibershell

Data Simulation

Step one: Understanding the ATLAS Detector

Allows detailed understanding of the detector material via location of interactions.

Jan. 20, 2012 8

ATLAS Higgs, HEP and KoRIA Dr. Jaehoon Yu 9

• Important first steps are the verification of the Standard Model physics at √s = 7 TeV • W/Z weak vector boson are powerful tools to constrain PDF’s and to understand detector

Step two: Verify SM Weak Bosons

Jan. 20, 20129


Of course, we see Z ee and μμ!!Z ee candidate

Total efficiency : ~ 30% Main background: QCD S/B ~ 100

Z μμ candidate

Total efficiency: ~ 40%Main background: tt, Z ττ S/B ~ 400

Jan. 20, 2012 10


Step 3: Understanding SM background to Higgs!!

Jan. 20, 2012 11

W x-sec vs CMS EnergyW+Njet x-sec

Validation of theoretical predictions!!


12Jan. 20, 2012

Higgs x-sec and Branching Ratio130GeV


13Jan. 20, 2012

ATLAS Higgs Search Strategy• Use production

– MH<130GeV• dominant decay

– High QCD background• cleanest but low BR• with leptonic decays of t Small branching ratio

– 130GeV<MH<2MZ:– MH>2MZ:

• Use multi-lepton final state from decays of bosons• final state dominated by QCD production of top.

• Use WH or ZH production at low mass (MH<120GeV)– Use leptonic decay of bosons with two b-jets.

H bb

gg H

* *, H WW H ZZ

H H t t

, , H WW H ZZ H tt

tt


LEP EWWG:http://www.cern.ch/LEPEWWG 114<MH<300+700-186 GeV

What do we know on Higgs before LHC?

MW ~ M t2 ln MH

2( )

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http://www.cern.ch/LEPEWWG


15Jan. 20, 2012

• Higgs boson is a ramification of the mass generation mechanism Highest priority in HEP and the last standing mystery

• Higgs decays in to various final states – H ZZ* 4e, 2e2μ and 2e2n – Very clean signal w/ modest background– Narrow mass peak– High PT electron identification key

Golden Channels in Higgs Searches

e- (μ-)e+ (μ+)

e-

e+

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After all selections: kinematic cuts, γ identification and isolation

22489 events with 100 < mγγ < 160 GeV observed in the data expected signal efficiency: ~ 35% for mH=125 GeV

mγγ spectrum fit with exponential function for background plus Crystal Ball + Gaussian for signalbackground determined directly from data

Main systematic uncertainties

Expected signal yield : ~ 20%H γγ mass resolution : ~ 14%H γγ pT modeling : ~ 8% Background modeling : ±0.1-5.6 events

Systematic uncertainties on signal expectation


Maximum deviation from background-onlyexpectation observed for mH~126 GeV: local p0-value: 0.27% or 2.8σ expected from SM Higgs: ~ 1.4σ local global p0-value: includes probability for such an excess to appear anywhere in the investigated mass range 110-150 GeV (“Look-Elsewhere-Effect”): ~7% (1.5σ)

Consistency of the data with thebackground-only expectation

Excluded (95% CL):114 ≤ mH ≤ 115 GeV, 135 ≤ mH≤ 136 GeV

Expected from SMHiggs at given mH

Where are we with Higgs searches?LEP

ATLAS+CMSCombination

ATLAStoday

Higgs could be discovered this year!!

Jan. 20, 2012 18ATLAS Higgs, HEP and KoRIA Dr. Jaehoon Yu

ATLAS Higgs in 2012??


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We could find the Higgs particle at the LHC this year!!Once found, the precision measurement of the Higgs becomes very important!!

Jan. 20, 2012

A Future Linear Collider• An electron-positron collider on a straight line for precision

measurements• CMS Energy: 0.5 – 1 TeV• 10~15 years from now (Japanese PM announced that they would bid

for a LC in Japan)• Takes 10 years to build the accelerator and the detector

L~31km


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Circumference ~6.6km~300 soccer fields

From CERN-open-2000-344, A. Sharma

GEM foil etching

70μm140μm

Gas Electron Multipliers (GEM)

GEM field and multiplication

Gains


21

100cmx100cm GEM Planes!!CERN GDD Workshop delivered the first 5 of 33cmx100cm GEM foils in 2010 Qualification completed!!

GEM DHCAL, J. Yu 22

Each of the GEM 100cmx100cm planes will consist of three 33cmx100cm unit chambers

Sept. 29, 2011


GEM Application Potential FAST X-RAY IMAGING

Using the lower GEM signal, the readout can be self-triggered with energy discrimination:

A. Bressan et al, Nucl. Instr. and Meth. A 425(1999)254F. Sauli, Nucl. Instr. and Meth.A 461(2001)47

9 keV absorption radiography of a small mammal (image size ~ 60 x 30 mm2)

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Radioactive Source Run with Internal Trigger

Jan. 20, 2012 24ATLAS Higgs, HEP and KoRIA Dr. Jaehoon Yu

Noisy channels masked out!

Can you see what the object is?

And in not too distant future, we could do …

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KoRIA, A World-class Accelerator Facility• Future high priority high energy physics topics will require

even higher energy and higher flux– Searching and precisely measuring the properties of SUSY

particles, dark matter, dark Energy and extra dimensions– Massive detailed studies of quark-gluon plasma!– Creating and accumulating anti-matters in mass!!

• KoRIA is a great starting point for establishing a versatile world-class accelerator facility in Korea

• Attract large number of scientists and promote advancement of accelerator related technologies

• Advance significantly the understanding the origin of the universe and help the whole human race in the long runJan. 20, 2012 26ATLAS Higgs, HEP

and KoRIA Dr. Jaehoon Yu

So how can KORIA get there?• The current KoRIA must be solidly established and carry out

its mission successfully • A clear vision for the long-term future of KoRIA must be

established from the get-go• Phased plan must be established to shape the future of

KoRIA even as the current KoRIA is being constructed• Build up manpower through the strong collaboration with

existing labs, such as Fermilab and CERN– Train domestically to increase technical manpower

• A stage for a historic future is set!• Need to get organized now to make it happen in 30yrs!

Jan. 20, 2012 27ATLAS Higgs, HEP and KoRIA Dr.

Jaehoon Yu

Conclusions• The LHC opened up a whole new kinematic regime

– The LHC performed extremely well this year• 1fb-1 expected but obtained over 5fb-1

• Latest results on Higgs show some hints of its existence – We expect over 10fb-1 additional data expected 2012

• We could find the Higgs particle this year or disprove its existence– In 2013 – 2014, an 18 month work on the accelerator toward the designed 14TeV

• Linear collider and advanced detectors are being developed for future precision measurements of Higgs and other newly discovered particles

• Outcome and the bi-product of HEP research impacts our daily lives – WWW came from HEP– GEM will make a large screen low dosage X-ray imaging possible

• KoRIA is a fruit of aspiration for excellence in basic sciences– Need to plan now to shape KoRIA to its long term future and to realize the dream

• Strong US-Korea collaboration will help this happen


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KoRIA in 30 years?

Jan. 20, 2012 29ATLAS Higgs, HEP and KoRIA Dr.

Jaehoon Yu

15 kilometers

Booster complex

recent atlas higgs results and koria

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