Finding the Higgs Boson pdgusers.lbl/~pequenao/camelia/index2.html

1. Finding the Higgs Boson http://pdgusers.lbl.gov/~pequenao/camelia/index2.html

2. LHC Practical Session - Intro • Who am I. Who are we? • What are we looking at/for? • Accelerating Particles • Detectors • The Higgs • The Benefits

3. Who am I? PhD Student at University of Liverpool Get paid a tax free allowance by the government After 3-4 years I write a thesis and become a Dr Lived in Geneva for 18 months * I hope, fingers crossed

4. What is CERN and the LHC? CERN: ConseilEuropéen pour la RechercheNucléaire An International Organisation (like UN, WHO, etc) for physics research, non Europeans are heavily involved as observers. More than 10000 users The Large Hadron Collider (LHC) is an apparatus to accelerate protons to be collided at four experiments The 2010 Budget was 1.1 billion CHF (730 million £), spread amongst member states. One cup of coffee per European citizen per year

5. What is CERN and the LHC?

6. The ‘Standard Model’ of Physics These quarks make protons and neutrons! These are our everyday particles that we are made of. We have extra Generations, similar to this but heavier

7. The ‘Standard Model’ of Physics These heavier generations do not occur in our usual lives, we need to use high energy colliders to make them. BUT we also need force carrying particles

8. The ‘Standard Model’ of Physics We are missing gravity here, we can’t fit it in this picture as Einstein described it

9. The ‘Standard Model’ of Physics We think Gravity should have a force carrying particle too, the Gravition but we can’t see it at our current energies!

11. As a Higgs analogy imagine a party. A celebrity enters & a huddle forms around him/her, making it hard to move, this is like the Higgs Particle Now a rumour circulates the celebrity is in the room, everyone asks each other about it. Soon a huddle of people forms, more join as they think the celebrity must be there, it again becomes hard to move. This is like the action of the Higgs field, giving particles mass, making it harder to move them.

12. Methods of Particle Physics 1) Concentrate energy on particles (accelerator) 2) Collide particles (recreate conditions after Big Bang) 3) Identify created particles in Detectors (search for new clues) 12

13. Accelerate charged particles using electric fields • Bend and focus the charged particles using magnetic fields In the LHC particles are accelerated to 7 000 000 000 000 volts (7 TeV) p p

14. CERN's mission: to build particle accelerators The Large Hadron Collider (LHC) is the most powerful instrument ever built to investigate particle properties. • Four gigantic underground caverns to host the huge detectors • The highest energy of any accelerator in the world • The most intense beams of colliding particles • It operates at a temperature colder than outer space

15. Computing • Huge amounts of data • Need lots of computing hours to process all of this • CERN created the GRID, linking computing clusters around the world for parellel processing

16. CERN: where the Web was born! Sir Tim Berners-Lee

17. How to x-ray a lorry ! Using wire chambers, invented at CERN

18. Medical applications PET scanners, MRIs 18

19. Medical applications AD-4 experiment trying to improve on proton therapy for cancer with anti-proton therapy 19

20. Summary: CERN is the largest laboratory for particle physics research in the world Basic research: study how the most basic matter we know (or theorise) behaves to describe how mass and forces work Summary Now for the Practical Part

21. Interactively finding the Higgs http://pdgusers.lbl.gov/~pequenao/camelia/index2.html Today, using real events from the LHC, you are going to be looking for the Higgs ,

22. Finding the Higgs We expect only 1 Higgs in 1,000,000,000,000 events • Unfortunately the Higgs decays in less than a millionth of a second • Have to detect the mundane things it decays into • However, we get these signatures million times more often from non Higgs events • Have to distinguish the Higgs from background, looking for a needle in a massive haystack!

23. Finding the Higgs Today you are going to try and look for Higgs decaying into four muons, via two Z particles

24. Finding the Higgs

25. Finding the Higgs Boson Time Charge Energy Position

26. Finding the Higgs

27. ATLAS A General Purpose Detector • Full coverage, meaning particles detected in virtually every direction, • Magnets, electronics and structural support inside detector

28. Finding the Higgs Boson Time Charge Energy Position

29. Interactively finding the Higgs http://pdgusers.lbl.gov/~pequenao/camelia/index2.html Pt = Momentum Transverse to the incoming beam GeV = Giga electronVolts, our units of Energy (We use Energy and Momentum interchangeably) Higgs Mass = 125GeV, Z mass = 91 GeV Invariant Mass = If a particle decays into two others, we can sum up their energy/momentum in the viewpoint of the original particle to tell us it’s mass

30. LHCb: Precision over small angles • Only detects particles going forward in 14 degree angle • High precision, detector only 5mm from collision point