Fermilab group review of qcd 10 019 measurement of the isolated photon production cross section
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Fermilab Group Review of : QCD-10-019, Measurement of the Isolated Photon Production Cross Section. Compilers: Jim Hirschauer & Don Lincoln. Comments received from: Jim Hirschauer, Don Lincoln, Kalanand Mishra , Lenny Spiegel & Fan Yang. General Observations.

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Compilers: Jim Hirschauer & Don Lincoln

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Fermilab group review of qcd 10 019 measurement of the isolated photon production cross section

Fermilab Group Review of: QCD-10-019, Measurement of the Isolated Photon Production Cross Section

Compilers: Jim Hirschauer & Don Lincoln

Comments received from: Jim Hirschauer, Don Lincoln,

KalanandMishra, Lenny Spiegel & Fan Yang


General observations

General Observations

  • Paper essentially in good shape

    • Scientifically

    • Grammatically

  • No show stoppers


Bigger comments

“Bigger” comments

  • Title “Isolated Photon” is a topological concept, while paper is aiming for “Direct Photon.” Phrasing in text interchanges “isolated, “prompt,” “isolated prompt” & “direct”. [Spiegel]


Line 39 vertex selection

Line 39: Vertex Selection

  • [Hirschauer] Quoting four degrees of freedom here does not make sense unless you describe the primary vertex fit. Just state that you require a primary vertex consistent with a real pp collision and cite the Trk POG PAS. (You already choose not to mention that, if you follow the POG recommendations, you require |z|<24 cm for the primary vertex.)

  • [Spiegel] The offline event selection requires a primary interaction vertex with at least four degrees of freedom. Does this mean the selection is on one and only one primary? Is a correction made in the cross-section analysis for events with no reconstructed primary or more than one reconstructed primary?..Degrees of freedom?


Lines 47 49 photon electron separation

Lines 47-49: Photon/Electron Separation

  • [Hirschauer] How do you quantitatively define "compatible with the observed location of the photon candidate" or "compatible with the energy of the photon candidate"? Here "behind the photon candidate" means only "within R < 0.15," right? Or does "behind the photon candidate" imply additional requirements that you leave out? If the former, you should drop "behind the photon candidate." If the latter, please specify the additional requirements.

  • [Spiegel] Electrons are rejected by requiring the absence of a track. The next sentence introduces a small contradiction: One could have a track without hits from the first two (barrel) layers..I think you can assume that the reader will appreciate the difference from a detector perspective between electrons and photons, and jump immediately to the pixel hit criterion.


Lines 56 57 photon isolation

Lines 56-57: Photon Isolation

  • [Hirschauer] Why do you use an annulus instead of a simple radius for IsoHCAL? In fact, even though it would be clear to many readers, we think it would be nice to explicitly describe the motivation for the topology of IsoTRK and IsoECAL isolation criteria,

  • [Lincoln] Maybe need some words for the delta eta and delta phi disparity?


Lines 94 100 photon efficiency

Lines 94-100: Photon Efficiency

  • [Hirschauer] What is the efficiency correction?

  • [Lincoln] Sounds scary and could be reworded. It sounds like all of the efficiencies are determined in Pythia+GEANT, and some are corrected for data/MC differences. But it doesn't sound like all are corrected for the differences, so shouldn't there be a systematic uncertainty and/or some discussion as to why the simulation is super good or something?


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