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OUTLINE o Brief introduction o What can we already or hope to explain about the physical universe? o Is string theory likely to provide new interconnected ...
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-- greatly improved understanding
Gordy Kane, Michigan Center for Theoretical Physics, Physics Department
NOT 10 DIMENSIONS TESTABLE
NO PREDICTIONS
PREDICTION OF HIGGS BOSON MASS AND PROPERTIES FROM STRING THEORY!!
Particle physics is entering a very exciting era โ data from CERN LHC , (and from dark matter satellite and laboratory detection experiments), is beginning to emerge
Today finally a consistent theoretical framework to address basic questions physicists want to ask
String theory hard โ we try to find ways to make contact with experiment by using general arguments and properties, and work around some difficult issues โ can do this in certain areas!
String theorists โ study theory for its own sake
String phenomenologists โ traditional physics, find our string vacuum โ growing subfield for decade โ 11th international conference at Newton Institute, Cambridge June 2012; NSF SVP
String theory is exciting because it allows us to address many questions we want to understand
โ GENERIC โ ยป perhaps not theorem, but holds very generally โ just calculate naturally without special assumptions โ have to work hard to find or construct (non-generic) exceptions (if possible), and to show possible exceptions donโt have problems that exclude them
COMPACTIFY (small extra dimensions)
EMBED MSSM, study spectrum, masses of quarks and leptons, gauge group of forces โ now many examples of successful embeddings
Stabilize moduli, generate TeV scale from Planck scale, calculate supersymmetry breaking Lagrangian, study Higgs and LHC and DM predictions
We focus here, try to work around issues that are problems
Want to know our string vacuum
EXCITING THAT STRING THEORY ADDRESSES THE QUESTIONS -- but
Fortunately, increasingly active subfield of โ string phenomenology โ -- focuses on formulating testable string-based description of our world (formal string theorists study string theory for its own sake)
NSF has funded the โ String Vacuum Project โ, SVP, consortium of 8- universities โ support for PHD students in string phenomenology http://www.northeastern.edu/svp
2010 international string phenomenology meeting, Paris, http://stringpheno.cpht.polytechnique.fr/
2011 Madison http://conferencing.uwex.edu/conferences/stringpheno2011/index.cfm
2012 University of Cambridge (England), June, http://www.newton.ac.uk/programmes/BSM/bsmw05.html
String theory is too important to be left to string theorists
Vacuum is ground state, lowest energy state, of universe
Surprisingly some people have claimed that because string theories are naturally formulated at Planck scale high energies or small distances they cannot be tested!
Obviously collisions will never probe energy scales such as the Planck energy 10 16 TeV (about 10 15 times LHC), or see distances as small as 10-33^ cm
More fundamentally, what does it mean to test theories?
In what sense is F=ma testable?
-- claim about actual relation between forces and particle behavior -- might not have been correct -- can test it for any particular force, but not in general
In what sense is string theory testable? Same!!!
Predictions from F=ma Predictions from string theory
-- pick F, pick m -- compactify to 4D, choose manifold
-- find solutions -- find solutions
-- calculate acceleration a -- calculate Higgs boson mass, etc
โtheoryโ
Theories are Lagrangians, Hamiltonians โ they have many solutions โ the world, physical systems, are described by the solutions
Normally the system relaxes to the lowest energy state, where we study its properties
String theory like having Lagrangian, many solutions โ physical systems described by compactified string theories, in vacuum state
We want to describe our string vacuum
Can we do better than tests in particular compactifications?
10/11D theory to ANY manifold!
๏ Predictions for squark masses, cosmological history, Higgs boson mass and properties
DESCRIBE HIGGS PREDICTION โ somewhat technical
HIGGS MASS PREDICTION โ more detailed physics argument โ 3 slides
o Compactify to 4D โ generically have moduli fields that parameterize curled up space โ all corners of string/M-theory
o Moduli generically stabilized (get a potential energy, settle at minimum) by non-perturbative contributions to superpotential โ any moduli interactions ok, donโt need to be able to calculate them
o Moduli quanta couple universally via gravity to everything โ can write operators for widths, ฮโผM (^3) mod /M (^2) pl with coefficient โผ unity โ can check coefficient in model, calculate moduli lifetime
o Generically, to avoid cosmology problems such as destroying good nucleosynthesis results, or overclosing universe, moduli must decay before nucleosynthesis โ [any possible ways out less likely as more studied, non-generic โ no workable example โ for late inflation see Fan Reece Wang]๏ M (^) mod ๏ 30 TeV
