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ADD Large Extra Dimensions vs Randall-Sundrum

Braneworld & the Bulk· within family

	ADD Large Extra Dimensions Speculative	Randall-Sundrum Speculative
Proposed	1998	1999
Key figures	Nima Arkani-Hamed, Savas Dimopoulos, Gia Dvali	Lisa Randall, Raman Sundrum
In one sentence	The hierarchy problem is solved by allowing gravity to dilute into up to seven large extra dimensions.	Our universe is a 3-brane in a 5D Anti-de-Sitter bulk. The exponential warp factor explains why gravity is so weak.
Predictions	Deviations from Newton's law at the size of the extra dimensions Production of microscopic black holes at TeV colliders Kaluza-Klein graviton emission in scattering experiments	Gravity weakens at very short distances (sub-millimeter scale) Kaluza-Klein graviton modes at TeV scale Telltale signatures at high-energy colliders like the LHC: resonance peaks where graviton modes decay into pairs of particles, or missing-energy events where gravitons escape the detector
Where it breaks	Sub-millimeter gravity tests have not seen deviations LHC has not produced microscopic black holes Simplest ADD scenarios excluded by collider searches Astrophysical constraints (supernova energy loss) further constrain it	No KK gravitons or short-distance gravity deviations seen at LHC Original RS1 requires fine-tuning
Key unresolved problem	The ruled-out problem: short-range gravity experiments and LHC collider searches have already excluded the simplest ADD large-extra-dimension scenarios, leaving no natural settings still standing.	The moduli stabilization problem: nothing in the model pins down the gap between the two branes, so this distance is a free dial you set by hand rather than something the theory predicts.
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ADD Large Extra Dimensions

1998 · Speculative

Randall-Sundrum

1999 · Speculative

Proposed

1998

1999

Key figures

Nima Arkani-Hamed, Savas Dimopoulos, Gia Dvali

Lisa Randall, Raman Sundrum

In one sentence

The hierarchy problem is solved by allowing gravity to dilute into up to seven large extra dimensions.

Our universe is a 3-brane in a 5D Anti-de-Sitter bulk. The exponential warp factor explains why gravity is so weak.

Predictions

Deviations from Newton's law at the size of the extra dimensions
Production of microscopic black holes at TeV colliders
Kaluza-Klein graviton emission in scattering experiments

Gravity weakens at very short distances (sub-millimeter scale)
Kaluza-Klein graviton modes at TeV scale
Telltale signatures at high-energy colliders like the LHC: resonance peaks where graviton modes decay into pairs of particles, or missing-energy events where gravitons escape the detector

Where it breaks

Sub-millimeter gravity tests have not seen deviations
LHC has not produced microscopic black holes
Simplest ADD scenarios excluded by collider searches
Astrophysical constraints (supernova energy loss) further constrain it

No KK gravitons or short-distance gravity deviations seen at LHC
Original RS1 requires fine-tuning

Key unresolved problem

The ruled-out problem: short-range gravity experiments and LHC collider searches have already excluded the simplest ADD large-extra-dimension scenarios, leaving no natural settings still standing.

The moduli stabilization problem: nothing in the model pins down the gap between the two branes, so this distance is a free dial you set by hand rather than something the theory predicts.

Reader vote

No votes yet