282 research outputs found
Particle physics catalysis of thermal Big Bang Nucleosynthesis
We point out that the existence of metastable, tau > 10^3 s, negatively
charged electroweak-scale particles (X^-) alters the predictions for lithium
and other primordial elemental abundances for A>4 via the formation of bound
states with nuclei during BBN. In particular, we show that the bound states of
X^- with helium, formed at temperatures of about T=10^8K, lead to the catalytic
enhancement of Li6 production, which is eight orders of magnitude more
efficient than the standard channel. In particle physics models where
subsequent decay of X^- does not lead to large non-thermal BBN effects, this
directly translates to the level of sensitivity to the number density of
long-lived X^-, particles (\tau>10^5 s) relative to entropy of n_{X^-}/s <
3\times 10^{-17}, which is one of the most stringent probes of electroweak
scale remnants known to date.Comment: Some typos correcte
Novel direct detection constraints on light dark matter
All attempts to directly detect particle dark matter (DM) scattering on
nuclei suffer from the partial or total loss of sensitivity for DM masses in
the GeV range or below. We derive novel constraints from the inevitable
existence of a subdominant, but highly energetic, component of DM generated
through collisions with cosmic rays. Subsequent scattering inside conventional
DM detectors, as well as neutrino detectors sensitive to nuclear recoils,
limits the DM-nucleon scattering cross section to be below cm
for both spin-independent and spin-dependent scattering of light DM.Comment: 7 pages revtex4, 3 figures. Version to appear in Phys. Rev. Let
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