Astrophysical constraints on large extra dimensions

Abstract

In the Kaluza-Klein (KK) scenario with n large extra dimensions where gravity propagates in the 4+n dimensional bulk of spacetime while gauge and matter fields are confined to a four dimensional subspace, the light graviton KK modes can be produced in the Sun, red giants and supernovae. We study the energy-loss rates through photon-photon annihilation, electron-positron annihilation, gravi-Compton-Primakoff scattering, gravi-bremsstrahlung and nucleon-nucleon bremsstrahlung, and derive lower limits to the string scale M S . The most stringent lower limit obtained from SN1987A leads to M S > 30−130 TeV (2.1−9.3 TeV) for the case of two (three) large extra dimensions.

TESTS OF THE GRAVITATIONAL INVERSE-SQUARE LAW

“…The case n = 2, R * = 0.3 mm, is inconsistent with the results of Reference (71). This case is even more strongly constrained by the observation of the neutrinos from supernova 1987A (72,73,74,75,76). Gravitational radiation into the extra dimensions would rapidly cool the supernova before the neutrinos could be emitted, imposing a con-straint R * < 0.7 µm.…”

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

“…Although this latter bound is easily evaded for the small-hierarchy models considered here, they provide a stronger test for the large-hierarchy case since they robustly require M 6D > ∼ 10 TeV. Much more stringent bounds are also possible if the extra-dimensional KK modes have significant branching fractions into observable particles, like photons or gluons [116][117][118][119][120]. In this case the absence of a γ-ray signal in the EGRET satellite implies M 6D > ∼ 40 TeV for the large-hierarchy case (dropping to M 10D > ∼ 40 GeV when all six dimensions are similar in size).…”

“…Astrophysical systems provide strong constraints on large extra dimensions due to the new energy-loss channels such dimensions would provide for stellar systems and supernovae [3,4,[116][117][118][119][120]. Perhaps surprisingly, these bounds are even stronger than collider limits despite the much lower energies to which they have access: ambient temperatures set the typical energies as E ∼ T ∼ 10 MeV.…”

Relaxing cosmological constraints on large extra dimensions

“…We then find that the above constraints are significantly ameliorated by such decays. Note also that astrophysical constraints [17,18,19,20] will be relaxed too, since in our scenario the fundamental scale of gravity is larger then in previous analyses (For another way to avoid these constraints see [21]). However, new constraints become significant, the most stringent one coming from the requirement that the graviton decay products do not destroy the predictions of the abundances of light elements created during Big-Bang Nucleosynthesis (BBN).…”