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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeDec 23rd 2019

    starting something – not done yet

    v1, current

    • CommentRowNumber2.
    • CommentAuthorUrs
    • CommentTimeJul 2nd 2024

    added pointer to:

    diff, v5, current

    • CommentRowNumber3.
    • CommentAuthorDavid_Corfield
    • CommentTimeJul 2nd 2024

    What does the “nearly” mean? Presumably something is missing.

    • CommentRowNumber4.
    • CommentAuthorUrs
    • CommentTimeJul 2nd 2024

    In these low dimensions the spacetimes are not quite AdS and the field theories are not quite conformal.

    The established term for this situation is “nearly AdS/CFT” (cf. search results for “nearly AdS” and “nearly AdS/CFT”)

    • CommentRowNumber5.
    • CommentAuthorDavid_Corfield
    • CommentTimeJul 2nd 2024

    Thanks!

    • CommentRowNumber6.
    • CommentAuthorDavidRoberts
    • CommentTimeJul 2nd 2024

    Is it nearly AdS because you don’t need to impose that asymptotic condition (and it might indeed be), or because it can’t be so?

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeJul 2nd 2024
    • (edited Jul 2nd 2024)

    from Maldacena, Stanford & Yang 2016 (“Conformal symmetry and its breaking in two-dimensional nearly anti-de Sitter space”):

    pure gravity in AdS 2AdS_2 is inconsistent with the existence of finite energy excitations above the AdS 2AdS_2 vacuum [1, 2, 3]. Nevertheless, there is a sense in which nearly AdS 2AdS_2 gravity is well defined.

    • CommentRowNumber8.
    • CommentAuthorDavidRoberts
    • CommentTimeJul 2nd 2024

    That doesn’t quite answer my question. Does “pure gravity in AdS 2AdS_2” mean in a 2d spacetime that’s asymptotically AdS, or literally just AdS? I presume you are trying to tell me that the answer to my question is the second option? I don’t care about a citation, because I’m not a physicist and I can’t do anything with it.

    • CommentRowNumber9.
    • CommentAuthorUrs
    • CommentTimeJul 3rd 2024
    • (edited Jul 3rd 2024)

    The qualifier “nearly” is about something different than “asymptotically”.

    People generally consider spacetimes that are “both”: asymptotically nearly AdS 2AdS_2, e.g. Gao, Jafferis & Kolchmeyer 2022.

    • CommentRowNumber10.
    • CommentAuthorDavidRoberts
    • CommentTimeJul 4th 2024

    I understand that. Here’s the article intro:

    The special case of AdS/CFT duality in dimensions 2/1. is called “nearly” AdS2/CFT1 because in these degenerate low dimensions the quantum field theory in duality is not quite conformal and the ambient spacetime is not quite asymptotically anti de Sitter.

    Is it “not quite asymptotically anti de Sitter” because it is impossible (due to physical, or mathematical, reasons) to have the duality while being asymptotically anti de Sitter. Or is it more of a red herring principle type thing, like how non-commutative algebra includes commutative algebra, and so one just has additional freedom and can allow asymptotically AdS as well as not quite asymptotically AdS?

    pure gravity in AdS 2AdS_2 is inconsistent with the existence of finite energy excitations

    By “in AdS 2AdS_2” do they mean any asymptotically AdS spacetime? Is this physicist imprecision?

    • CommentRowNumber11.
    • CommentAuthorDavidRoberts
    • CommentTimeJul 4th 2024

    I’m sorry to be pedantic, but if I can’t tell what the intro sentence is implying, even with additional clarifying remarks, then I believe it needs to be tweaked.