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Generating hierarchy and inflation in supergravity

Generating hierarchy and inflation in supergravity. Tirthabir Biswas IGC, Penn-State University With A. Notari, hep-ph/0511207 With A. Notari, S. Alexander & N. Okada in prep. The Hierarchy Problem. Fundamental scales are widely seperated Why is gravity so much weaker than Electro-weak?

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Generating hierarchy and inflation in supergravity

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  1. Generating hierarchy and inflation in supergravity Tirthabir Biswas IGC, Penn-State University With A. Notari, hep-ph/0511207 With A. Notari, S. Alexander & N. Okada in prep.

  2. The Hierarchy Problem Fundamental scales are widely seperated Why is gravity so much weaker than Electro-weak? Related (?) hierarchies: • Little hierarchy problem: • Hierarchy in quark masses: few MeV to Tev Attempts at solving the Hierarchy problem: • SUSY: if broken at ~ Tev can protect the hierarchy • Extra dimensions: Single fundamental mass scale (Mew) Mpl is derived, depends on extra-dimensions. Ratio can be made small by having them warped [RS] or large [ADD]

  3. Old Inflation (Guth) Slow-roll Inflation very successful, but • Concrete realization in ST or PP have been difficult • Typical scenarios involve fine tuning issues Inflation from false vacuum energy Why can’t it work? • If tunneling rate , the Hubble rate not enough inflation • If , never-ending inflation

  4. “Graceful” Old Inflation f(Φ) has a minimum, e.g. • Non-minimal coupling implies Φ & effective Mpl evolves during inflation from false vacuum • Even if initially Hubble rate decreases as Planck scale increases Inflation ends when • At this point bubbles nucleate and collide and reheats the universe • Einstein frame: hill top inflation with & reproduces observed tilt & amplitude

  5. Generating Hierarchy • When exponential inflation ends, & f(Φ) ~ O(1) • Universe expands as power law still driven by false energy as long as f(Φ) > Φ2 f(Φ) starts to grow • Finally the universe tunnels from the false vacuum having generated

  6. Future Research Signatures • Fundamental scale ~ Tev, new physics at LHC • Reheat temperature ~ Tev, gravity waves detectable at LISA. Accurate calculation required. Missing • Concrete PP or ST (supergravity) set-up • Requires a small hierarchy • A small “unprotected” parameter β • Quasi-periodic potential to stabilize Φ after tunneling to avoid 5th force constraints • Why SM doesn’t couple to Φ?

  7. Supergravity Embedding Advantages • Non-minimal coupling: Naturally given by Kahler potential But, it also determines kinetic piece. What works? & • Hierarchy: power law phase inflating • False vacuum: In SQCD such non-susy vacuum exists[Intrilligator et. al] Moreover, & one can have[Dine et. al] One can have long lived metastable vacua • Periodic potential: A coupling of Φ to the SQCD sector generates an F F† term which generates a periodic potential for Φ via chiral condensation of fermions.

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