Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

146 submissions , 123 unreviewed
3,961 questions , 1,408 unanswered
4,890 answers , 20,766 comments
1,470 users with positive rep
506 active unimported users
More ...

what is QCD Background?

+ 5 like - 0 dislike
41 views

I am looking at some papers in particle physics and came across 2 terms called QCD Background and ABCD method (control region and signal region). When I searched them on Google, could not get much information about them. Could someone either of those terms in a simple way for a non-physicist?

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user Damian Dulkawie
asked Apr 9, 2014 in Theoretical Physics by Damian Dulkawie (25 points) [ no revision ]

1 Answer

+ 4 like - 0 dislike

In simple terms QCD as a "background" usually refers to LHC research where hadronic jets create a lot of particles that clutter up the results you're trying to see. I think it has become a slang term and the use is discouraged.

ABCD method is a tool used to separate the particles of interest (signal) from the "other stuff" (background) made by the jets. It is a set of boundaries that relies on the fact that you have two independent distributions to distinguish between signal and background. See section 5.3 here http://dare.uva.nl/document/221955

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user user6972
answered Apr 10, 2014 by user6972 (40 points) [ no revision ]
First of all thanks for your reply. So, can I say that everything other than what I am looking for in the final state is a background?

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user Damian Dulkawie
The term "background" is not discouraged, at least not that I've ever heard. Its use is ubiquitous in the particle physics community.

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user David Z
@DavidZ I meant the mix of terms "QCD Background" where QCD is a theory and background don't really go together. I think the CMS doesn't like it used in publications.

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user user6972
@DamianDulkawie Yes, "background is a blanket term that covers the non-signal". We used to say "this year's signal next year's background" :). 30 years ago QCD was the sought for signal and the parton model provided the background.

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user anna v
@user6972 well, that may be something CMS does, but in particle physics in general, "QCD backgrounds" is still a reasonably common phrase.

This post imported from StackExchange Physics at 2014-04-13 14:34 (UCT), posted by SE-user David Z

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
p$\hbar$ysicsOve$\varnothing$flow
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
To avoid this verification in future, please log in or register.




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...