LHCLHC: the unbelievable in pursuit of the : the unbelievable in pursuit of the unimaginableunimaginable

Kajari MazumdarDepartment of Experimental High Energy Physics

Tata Institute of Fundamental ResearchMumbai

What principles govern energy, matter, space and time at the most elementary level?

• What is the world made up of? What is the world made up of? • How does it work?How does it work?High Energy Physics tries to answer them all!High Energy Physics tries to answer them all!

Eternal Questions

92 Elements Atoms

Nuclei (and Electrons) protons & neutrons

quarks ?

What lies within…?What lies within…?

?

The probe wavelength should be smaller than the distance scale to be probed: << h/p = hc/E

xE

41 mm 10 eV

20 1310 m 10 eV10 TeV

ToolTool

21 nm 10 eV (1 TeV = 1012 electronVolt = 1.6 * 10 -7 Joule)

8.6 Km

Price Tag: US $ 9.1 billion

No of scientists: 8000+

LHC is the Biggest and most Expensive Science Experiment ever

attempted

Technological progress pushes frontiers of basic science research and there are important spin offs.Eg. World Wide Web!

Working Principle of a Collider Machine

What will happen in LHC

Mammoth detectors will register signals

• LHC takes us back in time towards the beginning of the universe!at an epoch of 10-12 sec. after the big bang.

•Earlier experiments have probed the prevailing situation upto a time t ≈ 10-10 s, when the world was as hot as 1015 K

•Protons and neutrons formed around: t ≈ 10-4 s, 1013 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!

Cosmic Recipe: How we understand the universe

• 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!

Standard Model (SM) of Particle Physics as of today

• 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!

Relative strengths: 10 -40: 10 -5: 10-2: 1

We got to unravel the mystery of mass!

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!

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.

Typical LHC Event

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

About 25 faculty, 20 students from Indiaat present

Installation of detector components built in India (2006)

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 10-12 years.

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

Extra Dimensions: String theory with Radical ideas!

• Different particles and forces are just different oscillation modes of tiny strings, of length ~ 10-33 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 10 -25 sec after creation due toHawking Radiation!

No threat whatsoever of any kind.

Like asking what a new continent is going to be like when we can just glimpse the shore….

What do we expect the LHC to find?Many good reasons to discover Higgs boson and more

For the rest…

Four possible scenarios (J. Bagger et al hep-ex/0007022)

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

THANK YOU

TransPlanckian phenomenon: Laboratory Black Holes

S.B. Giddings, S. Thomas, PRL 65 (2002) 056010 S. Dimopoulos, G. Landsberg, PRL 87 (2001) 161602

Hawking radiation

Black Hole production

In large extra dimensions Schwarzchild radius of proton increases from 10-33 to 10-17 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 10-25 s spewing out many particles isotropically in the detector.