Observational legacy of preon stars: Probing new physics beyond the CERN LHC

We discuss possible ways to observationally detect the superdense cosmic objects composed of hypothetical subconstituent fermions beneath the quark/lepton level, recently proposed by us. The characteristic mass and size of such objects depend on the compositeness scale, and their huge density cannot arise within a context of quarks and leptons alone. Their eventual observation would therefore be a direct vindication of physics beyond the standard model of particle physics, possibly far beyond the reach of the Large Hadron Collider (LHC), in a relatively simple and inexpensive manner. If relic objects of this type exist, they can possibly be detected by present and future x-ray observatories, high-frequency gravitational wave detectors, and seismological detectors. To have a realistic detection rate, i.e., to be observable, they must necessarily constitute a significant fraction of cold dark matter.

Figure 1

Constraints on the mass of compact preon dark matter (CPDM) objects vs. the compositeness energy scale, $\Lambda$, which is related to the length-scale of a composite top quark by $\hslash c/\Lambda$. The estimate for the maximum mass of objects formed in the early universe, $M_H(\Lambda ,g_{\mathrm{eff}})$, is the mass within the horizon at the time of the preon phase transition, where $g_{\mathrm{eff}}$ is the effective number of degrees of freedom in the preon phase. The LHC will probe compositeness scales up to about $40\mathrm{TeV}$. The maximal mass of unobserved compact dark matter objects is $\sim {10}^{23}\mathrm{kg}$ and femtolensing searches rule out $\sim {10}^{14}<M<{10}^{15}\mathrm{kg}$. No observational technique can presently resolve objects with masses below ${10}^{14}\mathrm{kg}$. See the text for details.

Figure 2

Femtolensing of a gamma-ray burst (GRB) with model spectrum $(E/E_0{)}^{-1}$, for three different widths of the source, ${\sigma }_s$. The GRB has a fixed position relative to the optical axis, $r_s=0.5$, see text. These spectra were calculated with the online interface [38].

Figure 3

Ginga spectral data of GRB 880205 for a power law model of the incoming spectrum (dashed line), which is ruled out at more than 99.99% confidence level [28]. The observed spectrum has line features at $h\nu \simeq 20$ and $40\mathrm{keV}$, which could be due to gravitational lensing (diffraction) of a Gaussian source by a $\sim {10}^{16}\mathrm{kg}$ object at redshift $z\sim 1$ (solid line). The spectral data depend on the model used and should not be directly compared to the diffraction spectrum, which therefore has been shifted downwards to enhance viewing [29]. The main concern here is the location of the line features.

Figure 4

Amplitude vs frequency for gravitational waves emitted from an equal-mass binary system in circular orbit. The distance is such that 10 coalescence events per year is expected within that range, i.e., $N_c=10$ in (17). The solid lines denote the frequency-amplitude relation for different masses, $M$, of the CPDM objects, in steps of 1 order of magnitude. The coalescence time (14) is denoted by the dotted lines, also in steps of 1 order of magnitude. The dash-dotted line corresponds to an orbital velocity of 10% of the speed of light. Dashed lines denote the lower sensitivity curves for an observational time of 5 years with EURO, according to two different design specifications (shot-noise limited antenna with a knee-frequency of 1000 Hz and a xylophone-type interferometer). The sensitivity of the first prototype 100 MHz detector in the UK [45] is presently insufficient to detect CPDM coalescence events. The shaded region, $h<{10}^{-30}$, apparently is beyond reach of experiments and could be polluted by the relic gravitational wave background, see 43 and references therein.