No Arabic abstract
Since Wittens seminal 1984 paper on the subject, searches for evidence of strange quark nuggets (SQNs) have proven unsuccessful. In the absence of experimental evidence ruling out SQNs, the validity of theories introducing mechanisms that increase their stability should continue to be tested. To stimulate electromagnetic SQN searches, particularly space searches, we estimate the net charge that would develop on an SQN in space exposed to various radiation baths (and showers) capable of liberating their less strongly bound electrons, taking into account recombination with ambient electrons. We consider, in particular, the cosmic background radiation, radiation from the sun, and diffuse galactic and extragalactic $gamma $-ray backgrounds. A possible dramatic signal of SQNs in explosive astrophysical events is noted.
We have computed the charge that develops on an SQN in space as a result of balance between the rates of ionization by ambient gammas and capture of ambient electrons. We have also computed the times for achieving that equilibrium and binding energy of the least bound SQN electrons. We have done this for seven different settings. We sketch the calculations here and give their results in the Figure and Table II; details are in the Physical Review D.79.023513 (2009).
Bounds on masses and abundances of Strange Quark Nuggets (SQNs) are inferred from a seismic search on Earth. Potential SQN bounds from a possible seismic search on the Moon are reviewed and compared with Earth capabilities. Bounds are derived from the data taken by seismometers implanted on the Moon by the Apollo astronauts. We show that the Apollo data implies that the abundance of SQNs in the region of 10 kg to one ton must be at least an order of magnitude less than would saturate the dark matter in the solar neighborhood.
The axion quark nuggets introduced in cite{zhitnitsky}-cite{zhitnitsky13} are a candidate for cold dark matter which, in addition, may be relevant in baryogenesis scenarios. The present work studies their evolution till they enter in the colour superconducting phase. This evolution was already considered in cite{zhitnitsky5}, where it is concluded that a large chemical potential $mu$ is induced on the bulk of the object. The baryon number accumulated at the domain wall surrounding the object is taken as predominant in cite{zhitnitsky5}, and it is suggested that internal and external fluxes are compensated and can be neglected. In the present work, the possibility that the bulk contribution to the baryon number may be relevant at initial stages and that the object may emit a large amount of neutrinos due to quark-antiquark annihilations is taken into account. The outcome is a more violent contraction of the object and, perhaps, a more effective cooling. Therefore, the resulting objects may have a smaller size. Even taking into account these corrections, it is concluded that the cosmological applications of these objects are not spoiled. These applications are discussed along the text.
In the simulation of QCD with 2+1 flavors of Wilson fermions, the positivity of the fermion determinant is generally assumed. We present evidence that this assumption is in general not justified and discuss the consequences of this finding.
Correlations between the strange quark mass, strange quark condensate $langle bar s srangle$, and the kaon partially conserved axial current (PCAC) relation are developed. The key dimensionless and renormalization-group invariant quantities in these correlations are the ratio of the strange to non-strange quark mass $r_m=m_s/m_q$, the condensate ratio $r_c=langle bar s srangle/langle bar q qrangle$, and the kaon PCAC deviation parameter $r_p=-m_slangle bar s s+bar q qrangle/2f_K^2m_K^2$. The correlations define a self-consistent trajectory in the ${r_m,r_c,r_p}$ parameter space constraining strange quark parameters that can be used to assess the compatibility of different predictions of these parameters. Combining the constraint with Particle Data Group (PDG) values of $r_m$ results in ${r_c,r_p}$ constraint trajectories that are used to asses the self-consistency of various theoretical determinations of ${r_c,r_p}$. The most precise determinations of $r_c$ and $r_p$ are shown to be mutually consistent with the constraint trajectories and provide improved bounds on $r_p$. In general, the constraint trajectories combined with $r_c$ determinations tend to provide more accurate bounds on $r_p$ than direct determinations. The ${r_c,r_p}$ correlations provide a natural identification of a self-consistent set of strange quark mass and strange quark condensate parameters.