Related Clues:

• It's little matter
• It may be positive or negative
• Half the dictionary?
• Powerful mite
• Something to smash
• Label on the first of two file drawers, maybe
• Lepton's locale
• Quantum physics particle
• Particle with a 'flavor'
• Physicist's subject
• Small matter?
• Small bit
• It's always charged
• Bit of nuclear physics
• Supercollider projectile