1. LHC: the unbelievable in pursuit of the unimaginable
Kajari Mazumdar
Department of Experimental High Energy Physics
Tata Institute of Fundamental Research
Mumbai

2. Eternal Questions
What principles govern energy, matter, space and time at the most elementary level?
What is the world made up of?
How does it work?
High Energy Physics tries to answer them all!

3. 92 Elements
Atoms
Nuclei (and Electrons)
protons & neutrons
quarks ?
What lies within…?
Tool
The probe wavelength should be smaller than the distance scale to be probed: l<< h/p = hc/E
(1 TeV = 1012 electronVolt
= 1.6 * Joule)

4. Technological progress pushes frontiers of basic
LHC is the Biggest and most Expensive Science Experiment ever attempted
Price Tag: US $ 9.1 billion
No of scientists:
8.6 Km
Technological progress
pushes frontiers of basic
science research and there are important spin offs.
Eg. World Wide Web!

5. Working Principle of a Collider Machine

6. What will happen in LHC
Mammoth detectors will register signals

7. Cosmic Recipe: How we understand the universe
LHC takes us back in time towards the beginning of the universe!
at an epoch of sec. after the big bang.
Earlier experiments have probed the prevailing situation upto a time t ≈ s, when the world was as hot as 1015 K
Protons and neutrons formed around: t ≈ 10-4 s, K
Nuclei are formed after t = 3 minutes, 109 K
(equivalent energy density ~0.1 MeV, distance scale ~10-12 m)
Today: t = 14 Billion years since the beginning, 3 K
Present wisdom: Behaviour of matter particles can be explained in terms of very few fundamental interactions, which might have evolved over time as the universe cooled down from a single unified one.
GRAND UNIFIED THEORY!

8. Standard Model (SM) of Particle Physics as of today
4 types of basic forces :
Gravitational, Weak, Electromagnetic, Strong.
And 2 types of fundamental particles :
(i) fermions (matter particles like electron, quarks)
(ii) bosons (carrier particles, like photon)
Almost all the predictions of SM match very well, till date, with
experimental observations.SM is still not a satisfactory Theory!
Relative strengths:
10 -40: 10 -5: 10-2: 1
One of the most disturbing fault of our understanding as of today, is, we can’t explain the origin and the mass patterns of particles.
Theoretically, in an unified description, massless particles can be described very well.
But, in nature, we do encounter mass of elementary particles. Introduction of mass in the theory causes complications!

9. We got to unravel the mystery of mass!
Most plausible: all fundamental particles acquire mass by interacting with an all pervading field, as a consequence, this idea also evokes another fundamental particle, the Higgs Boson!
Higgs particle not yet seen have to hunt it out in experiment. e f==a
Strategy: Heavy particles (by nature unstable) of interesting properties should show up if enough energy is gathered to produce them. (E=mc2). They were produced, existed when universe was hot.
LHC is an exploratory, high energy, high intensity machine which can produce heavy particles of mass upto few TeV.
Need accelerators for high energy in a controlled fashion in the laboratory.
The primary goal of the LHC is to find the Higgs boson…
… if it isn’t found, to find out why it isn’t there!

10. Most sophisticated and complex detectors with size of big buildings.
Unprecedented computing challenge to be met by GRID technology.
TIFR, Mumbai is preparing to host one of the GRID computing centres for regional scientists
Typical LHC Event

11. About 25 faculty,
20 students from India
at present

12. Installation of detector components built in India (2006)

13. LHC Timeline First LHC studies were done in 1982
Project was approved in 1994 ; final decision in 1996
Construction started in 2002
First beams sent around the storage ring: September 10, 2008
Helium leak caused by electric short-circuit delayed start
Official inauguration: October 21, 2008
First collisions will start around summer 2009
By October 2009 collision energy should reach 10 TeV
Energy upgrade to 14 TeV by mid 2010
Higgs boson discovery (?) by 2012
Several Indian groups working for LHC accelerator and experiments for last years.

14. Interesting factoids about LHC:
LHC when running will consume as much power as a medium-sized European town
LHC budget is comparable to the GDP of a small country, e.g. Fiji or Mongolia
LHC vacuum is 100 times more tenuous then the medium in which typical communications satellites move
LHC magnetic fields of 8.4 Tesla are 100,000 times the Earth’s
LHC magnets will use 700,000 litres of liquid Helium and 12,000,000 litres of liquid Nitrogen
LHC protons will have energies comparable to that of a flying mosquito
LHC optical grid at 1.5 Gb/s could eventually make the Internet 300 times faster

15. Extra Dimensions: String theory with Radical ideas!
Different particles and forces are just different oscillation modes of tiny strings, of length ~ cm.
Instead of usual 3 spatial dimensions, there may be additional ones, which are curled up too small to be observed!
Gravity may appear weak only because its force is being shared with (or leaks into) other spatial dimensions.
Or, LHC may produce almost 10 Million completely harmless Micro Quantum Black Holes per year!
The Black Hole will disappear within sec after creation due to
Hawking Radiation!
No threat whatsoever of any kind.

16. What do we expect the LHC to find?
Many good reasons to discover Higgs boson and more
For the rest…
Like asking what a new continent is going to be like when we can just glimpse the shore….
Four possible scenarios
(J. Bagger et al hep-ex/ )

17. There is always the possibility that one may find something really exotic….

18. THANK YOU

20. TransPlanckian phenomenon: Laboratory Black Holes
S.B. Giddings, S. Thomas, PRL 65 (2002) S. Dimopoulos, G. Landsberg, PRL 87 (2001)
Hawking radiation

21. Black Hole production In large extra dimensions Schwarzchild
radius of proton increases from to cm
If the impact parameter of two colliding protons is smaller than this distance, they coalesce into a micro blackhole .
It evaporates, via Hawking radiation, within s spewing out many particles isotropically in the detector.