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The likelihood of GODs' existence: Improving the SN1987a constraint on the size of large compact dimensions

Christoph Hanhart, Jose A. Pons, Daniel R. Phillips, Sanjay Reddy

TL;DR

The paper investigates whether large gravity-only compact dimensions (GODs) can exist by analyzing the SN1987a neutrino signal with self-consistent proto-neutron star simulations that include KK-graviton emissivity. It uses emissivities anchored by the KK-graviton calculations of Hanhart et al. and a Bayesian likelihood framework to marginalize over uncertain PNS mass M and anti-neutrino temperature T_bar_nu, yielding robust constraints on the GOD radii. The main results give 95% CL bounds of R_2 ≤ 0.66 μm for two extra dimensions and R_3 ≤ 8×10^-4 μm for three, corresponding to a_2^0 = 0.022 MeV/baryon/s and a_3^0 = 0.0077 MeV/baryon/s. The bounds are more stringent than current collider or sub-millimeter gravity tests for two extra dimensions and remain robust against key astrophysical uncertainties, offering a principled framework for future galactic supernova analyses.

Abstract

The existence of compact dimensions which are accessible only to gravity represents an intriguing possible solution to the hierarchy problem. At present the strongest constraint on the existence of such compact Gravity-Only Dimensions (GODs) comes from SN1987a. Here we report on the first self-consistent simulations of the early, neutrino-emitting phase of a proto-neutron star which include energy losses due to the coupling of the Kaluza-Klein modes of the graviton which arise in a world with GODs. We compare the neutrino signals from these simulations to that from SN1987a and use a rigorous probabilistic analysis to derive improved bounds for the radii of such GODs. We find that the possibility that there are two compact extra dimensions with radii larger than 0.66 $μ$m is excluded at the 95% confidence level---as is the possibility that there are three compact extra dimensions larger than 0.8 nm.

The likelihood of GODs' existence: Improving the SN1987a constraint on the size of large compact dimensions

TL;DR

The paper investigates whether large gravity-only compact dimensions (GODs) can exist by analyzing the SN1987a neutrino signal with self-consistent proto-neutron star simulations that include KK-graviton emissivity. It uses emissivities anchored by the KK-graviton calculations of Hanhart et al. and a Bayesian likelihood framework to marginalize over uncertain PNS mass M and anti-neutrino temperature T_bar_nu, yielding robust constraints on the GOD radii. The main results give 95% CL bounds of R_2 ≤ 0.66 μm for two extra dimensions and R_3 ≤ 8×10^-4 μm for three, corresponding to a_2^0 = 0.022 MeV/baryon/s and a_3^0 = 0.0077 MeV/baryon/s. The bounds are more stringent than current collider or sub-millimeter gravity tests for two extra dimensions and remain robust against key astrophysical uncertainties, offering a principled framework for future galactic supernova analyses.

Abstract

The existence of compact dimensions which are accessible only to gravity represents an intriguing possible solution to the hierarchy problem. At present the strongest constraint on the existence of such compact Gravity-Only Dimensions (GODs) comes from SN1987a. Here we report on the first self-consistent simulations of the early, neutrino-emitting phase of a proto-neutron star which include energy losses due to the coupling of the Kaluza-Klein modes of the graviton which arise in a world with GODs. We compare the neutrino signals from these simulations to that from SN1987a and use a rigorous probabilistic analysis to derive improved bounds for the radii of such GODs. We find that the possibility that there are two compact extra dimensions with radii larger than 0.66 m is excluded at the 95% confidence level---as is the possibility that there are three compact extra dimensions larger than 0.8 nm.

Paper Structure

This paper contains 4 sections, 9 equations, 2 figures.

Table of Contents

  1. Introduction
  2. PNS Evolution with Additional Sources of Energy Loss and SN 1987a signal
  3. From simulations to bounds: the desirability of a likelihood analysis
  4. Improved bounds and discussion

Figures (2)

  • Figure 1: Comparison of the results of our simulations for a PNS with a baryonic mass of $M=1.6 ~M_\odot$ to the data from SN 1987a. N(t) denotes the integrated number of counts. We show results from a model without graviton emission (solid line), as well as the results with graviton emission for $a_2 = 0.01$ MeV/baryon/s (short-dashed line) and $a_2 = 0.1$ MeV/baryon/s (long-dashed line).
  • Figure 2: Contour levels of the function $q$ defined in Eq. (\ref{['eq:q']}): $(x-M)$ left panel; $(M-\log(a_2))$ middle panel; $(x-\log(a_2))$ right panel.