Recent content by crackjack

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    Java Suitability of Java for computational physics, as compared with C or F

    I wouldn't read too much into it. That SE community has been in beta, and does not have tags for charm++ or CAF or Julia or fault-tolerance either, none of which means anything about the current/future potential of these tools/languages/concepts in HPC. Dont mistake me - I am more comfortable...
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    Java Suitability of Java for computational physics, as compared with C or F

    In addition to my earlier reply, let me also pass on what I have been generally told/read over time: Real world constraints: Given unlimited resources (time, money, access to enough top-skilled programmer etc), a C/C++/FORTRAN program can certainly be tuned to perform better than a similarly...
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    Java Suitability of Java for computational physics, as compared with C or F

    I am debating with myself on this Java VM versus C/C++ question for a while now. I had also asked a related question at SciComp SE on this (I should have known better than asking it there when the scicomp SE did not even have a 'java' tag). A 2007 blog post ran some of those benchmarks, but...
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    Am I seeing the right stats for this forum?

    ignore[Approximately when were those numbers reset?] It would be nice to know the time trends for those metrics, like how data.stackexchange provides.
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    Am I seeing the right stats for this forum?

    The homepage of this forum gives the following stats: Threads: 638,474 Posts: 4,515,531 Members: 205,067 Are these the aggregates since the very first day this forum was founded (ie. 2001)? May I know what has been the trends for these metrics over time?
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    Usefulness of SUSY models when it cant exist at non-zero temperatures

    PS: I have also posted this question at the physics stackexchange You should read that review paper I posted above. Under non-zero temperatures, SUSY is always (spontaneously) broken, along with a goldstino associated with this breaking. But yes, since this is spontaneous breaking, the...
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    Usefulness of SUSY models when it cant exist at non-zero temperatures

    I too think, for the same reason (that people are still studying SUSY), thermal effects probably don't upset the advantages of SUSY much. The section above that paper's conclusion heuristically discusses how the goldstino from thermal breaking of SUSY mixes with the goldstino from the usual SUSY...
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    Usefulness of SUSY models when it cant exist at non-zero temperatures

    Unlike other symmetries (like electroweak symmetry), SUSY is spontaneously broken at any non-zero temperature due to some variation of the fact that the boundary conditions on bosons and fermions in thermal QFT are different. If this is the case, what is the rationale for considering SUSY...
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    Does Noether theorem apply to gauge symmetry?

    http://www.osti.gov/bridge/servlets/purl/6129984-GWXEJY/6129984.pdf The conserved charge in local gauge theories is not truly conserved. But local gauge symmetry is unphysical and has to be removed (gauge fixed), unlike global gauge symmetry. This "fixes" the local gauge charge into the a...
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    [Holography] Global symmetry in boundary corresponds to gauge symmetry in bulk?

    Thanks for the clarification! I still have a few questions, but that is because I lack a good intuitive understanding. Ah ok. I see what you mean (the integrated Ward identity). But I have never gone beyond the leading term - I always though it doesn't work for the exponential map. For...
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    [Holography] Global symmetry in boundary corresponds to gauge symmetry in bulk?

    I am very sorry - I still do not understand it. I understand this (from usual Noether's theorem), but not the rest of the first para. For example, I don't understand what is the current vector doing on the gauge group element effecting gauge transformations and why is it integrated over all...
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    Wilson Lattice Action and the Strong-Coupling Expansion

    Lets assume the gauge fields are sufficiently regular. Can we then look at this process of taking lattice spacing to zero, "a" -> 0, as running the theory from IR to UV? In this sense, the higher-dimensional operators (~ those of higher orders in "a") resemble irrelevant operators in...
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    [Holography] Global symmetry in boundary corresponds to gauge symmetry in bulk?

    what = May be the induced metric (~ Gibbons-Hawking surface term)? In the Hamiltonian formalism, this surface term gives the total energy of the (non-compact) spacetime. Ref: http://arxiv.org/abs/gr-qc/9501014
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    Wilson Lattice Action and the Strong-Coupling Expansion

    Thanks for the fast reply! (I will keep this in mind when editing. Sorry about the editing mess in my last post) Is it true that, theoretically speaking, the lattice Wilson action will exactly coincide with the Yang-Mills action in the continuum limit only when the Wilson action includes sum...
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    Wilson Lattice Action and the Strong-Coupling Expansion

    True, but I have also read that, while the simplest Wilson action (like in the paper I quoted) consists of 1x1 Wilson loops as fundamental excitations, there are more complicated Wilson actions (~ Symanzik's improvement) with longer Wilson loops that further reduce the error when taking the...
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