Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ph/0309173

Gamma rays from the Galactic bulge and large extra dimensions

Michel Casse·Jacques Paul·Gianfranco Bertone·Guenter Sigl
View original source ↗Read source document ↗Export metadata ↓

Abstract

An intriguing feature of extra dimensions is the possible production of Kaluza--Klein gravitons by nucleon-nucleon bremsstrahlung in the course of core collapse of massive stars, as pointed out by Hannestad and Raffelt. In this event Kaluza--Klein gravitons are copiously produced and a significant fraction of them remains trapped around the newly born neutron stars. They slowly decay into 2 gamma rays, making neutron stars gamma-ray sources. In this letter, we strengthen considerably the limits on the radius of compactification of extra-dimensions for small number $n$ of them, or alternatively the fundamental scale of quantum gravity, considering the gamma-ray emission of the whole population of neutron stars sitting in the Galactic bulge, instead of the closest member of this category. For $n=1$ the constraint on the compactification radius is $R<400μ$m, overlapping with the distance ($180μ$m) at which Newtons law is directly measured. In addition, for n=1 and n=2, the fundamental energy scale of quantum gravity is far beyond the collider technology. These results imply that if $n\lesssim4$ and if strong gravity is around a TeV, the compactification topology is to be more complex than that of a torus.

Explore related subjects

hep-phastro-phgr-qchep-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Michel Casse, Jacques Paul, Gianfranco Bertone, Guenter Sigl. 2004-03-24. Gamma rays from the Galactic bulge and large extra dimensions. https://doi.org/10.1103/physrevlett.92.111102

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Higgs-Portal Stueckelberg Dark Matter

We study dark photon dark matter X associated with a dark $U(1)_X$ gauge symmetry. To evade laboratory and cosmological constraints on kinetic mixing with the Standard Model $U(1)_Y$, we assign a $Z_2$-odd dark parity to X that forbids such mixing. The leading interactions then arise from gauge-invariant dimension-6 Higgs-portal operators, including both parity-even and parity-odd terms. We assume that the dark matter mass is generated via the Stueckelberg mechanism. In the interacting Stueckelberg EFT, a gauge-invariant dimension-6 parent reduces in unitary gauge to the nominal dimension-4 Higgs-portal interaction $(H^†H)X_μX^μ$, with its coefficient correlated with $m_X^2/Λ^2$, while additional derivative operators are organized by the same longitudinal-mode power counting. We investigate freeze-in production of X from Higgs-pair annihilations after reheating, incorporating both field-strength and Stueckelberg-allowed operators. First, we consider the case in which the Wilson coefficients of the gauge-invariant dimension-6 operators, C and $\tilde C$, are of order unity. Under a conservative single-cutoff power counting in which the strong-coupling scales of the longitudinal mode lie above the cutoff of the field-strength effective theory, we find that the Stueckelberg contributions remain subdominant in dark matter production. We emphasize that this ordering of scales is an explicit assumption rather than a universal consequence of perturbative unitarity. Next, we explore a more general situation in which C and $\tilde C$ are smaller than unity. In this second case, Stueckelberg-allowed operators can become comparable and generate contributions proportional to $T_{reh}^3$, $T_{reh}^5$, and $T_{reh}^7$, including sign-dependent interference effects. For both cases, we show that there exists a wide parameter space consistent with the observed dark matter relic density.

hep-ph↗
arXiv2026

Scaling laws for amplitude surrogates

Scaling laws describing the dependence of neural network performance on the amount of training data, the spent compute, and the network size have emerged across a huge variety of machine learning task and datasets. In this work, we systematically investigate these scaling laws in the context of amplitude surrogates for particle physics. We show that the scaling coefficients are connected to the number of external particles of the process. Our results demonstrate that scaling laws are a useful tool to achieve desired precision targets.

hep-ph↗
arXiv2026

Analysis of the $D_0^*(2300)$ resonance from lattice QCD under chiral symmetry

We reanalyze the lattice spectra for $I=1/2$ $Dπ$ scattering in the $A_1^+$ irreducible representation from [Phys. Rev. D 111, 014503 (2025)] to investigate the impact of chiral and SU(3) flavor symmetries in $S$-wave $Dπ$ scattering and the $D_0^*(2300)$ resonance. By fitting the phase shifts obtained via Lüscher's formula with both traditional and chirally modified effective-range expansion and $K$-matrix parameterizations, we find that the chiral factor shifts the extracted pole mass closer to the threshold (especially for resonances) and substantially reduces the resonance width. These findings are confirmed by unitarized chiral perturbation theory through a direct fit to the lattice spectra with both the single-channel and the $Dπ$-$Dη$-$D_s\bar{K}$ coupled-channel schemes. Once the coupled channels are incorporated, the two-pole structure of the $D_0^*(2300)$ emerges. The trajectories of the two poles are investigated by varying the pion mass.

hep-ph↗