No, visible light beams cannot appear black in color. Black is the absence of light or the absence of any color. In order for an object or a light beam to appear black, it must absorb or scatter all the incoming light without reflecting or transmitting any significant amount of it.
Visible light is composed of a range of wavelengths, from approximately 400 to 700 nanometers, which our eyes perceive as different colors. When all the wavelengths within the visible spectrum are present, we perceive the light as white. On the other hand, when an object or a beam of light absorbs all the wavelengths within the visible spectrum, it appears black because no light is being reflected or transmitted.
However, if a visible light beam is present, it means that light is being emitted or reflected by a source. Even if the light beam is very dim or has a low intensity, it still carries photons that contribute to its color. So, while a visible light beam can be very faint or close to darkness, it cannot be truly black in color.