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Rare Decays in Theories with LGS
Cosimo Bambi
Wayne State University
Based on the paper:C. Bambi, A.D. Dolgov and K. Freese, NPB 763, 91 (2007) [arXiv:hep-ph/0606321]
Search for B and L Number Violations, Berkeley, 22 September 2007
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Outline
• Gravitational Decays• Problems in Theories with LGS• Possible Solution: Classical BH Conjecture• Phenomenology
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Gravitational Decays
• Classical BHs violate global charges• Virtual BHs can mediate proton decay
(Zeldovich, 1976)
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Theories with LGS
• ADD model
• Strong gravity at short (sub-mm?) distances
• QG effects in particle physics
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p-decay in Theories with LGS
• Too fast proton decay!!!
• Solution:
i) No LGS:
ii) New suppression mechanism
(Adams et al., 2001)
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Classical BH Conjecture
Conjecture: virtual BHs satisfy this condition
Classical BHs cannot have arbitrary largeelectric charge and angular momentum
If MBH << MPl, BH must be neutral and have 0 spin
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Assumptions
• BH coupling to 2 or 4 particles is found from dimension arguments (probability of 2 or 4 particles to be inside BH horizon):
• BHs propagate only forward in time, no anti-BHs (Breaking of LI). No Et 1. For example, BHs cannot be in the t-channel of a reaction
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Comments
• In absence of any quantum theory of gravity, this is the simplest possibility
• Predictions are numerous and close to existing bounds
• Breaking of LI and of standard QFT rules is discussed in numerous literature
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Phenomenology
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Muon decay
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Other (Semi)-Leptonic Processes
BR < 10-11 (BRExp < 10-7 – 10-6)
Strongly suppressed
As above
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K–meson decay (1)
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K–meson decay (2)
If BHs are scalars and not pseudo-scalars (i.e. BHs have the quantum numbers of vacuum), 2 body decays are suppressed and not dangerous
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Scalar BHs – Summary
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Proton Decay
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Neutron–Antineutron Oscillation
Experimental bound:
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Neutron–Antineutron Oscillation(SUSY Extension)
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Heavy Quark Decays
• t-quark may not be the best candidate• B-mesons more promising
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Summary
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Conclusions
• Classical BH Conjecture: simple (but very speculative) solution to dangerous gravitationally induced decays in particle physics
• Rich phenomenology, possibly accessible in near future experiments