I often come across the term "background" in particle physics. Could someone explain what it exactly means?
closed as too broad by ZeroTheHero, AccidentalFourierTransform, Jon Custer, Yashas, user259412 Apr 26 '17 at 0:03
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Any general definition is bound to be abstract. I usually go with something like
Everything in a subset of your data where you have (or expect) a signal of some physics that isn't that signal is a background.
What that might consist of depends on the particular case. It is also worth noting that many data sets are subject to multiple analyses, and data that is signal in one may be background in another and vice versa.
Nor is this definition in any way special to particle physics, it's nearly ubiquitous in experimental work.