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Randall-Sundrum vs ADD Large Extra Dimensions

Braneworld & the Bulk· within family

	Randall-Sundrum Speculative	ADD Large Extra Dimensions Speculative
Proposed	1999	1998
Key figures	Lisa Randall, Raman Sundrum	Nima Arkani-Hamed, Savas Dimopoulos, Gia Dvali
In one sentence	Our universe is a 3-brane in a 5D Anti-de-Sitter bulk. The exponential warp factor explains why gravity is so weak.	The hierarchy problem is solved by allowing gravity to dilute into up to seven large extra dimensions.
Predictions	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	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
Where it breaks	No KK gravitons or short-distance gravity deviations seen at LHC Original RS1 requires fine-tuning	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
Key unresolved problem	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.	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.
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Randall-Sundrum

1999 · Speculative

ADD Large Extra Dimensions

1998 · Speculative

Proposed

1999

1998

Key figures

Lisa Randall, Raman Sundrum

Nima Arkani-Hamed, Savas Dimopoulos, Gia Dvali

In one sentence

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

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

Predictions

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

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

Where it breaks

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

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

Key unresolved problem

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.

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.

Reader vote

No votes yet