-- BradCox - 2017-06-01

Comments Set 1 Jeff Richman

Title: Search for natural supersymmetry in events with top quark pairs and photos in pp collisions at sqrt s = 8 TeV

Fine!

Comment: Abstract

Results are presented from a search for natural gauge-mediated supersymmetry in a scenario in which the top squark is the lightest squark, the next-to-lightest SUSY particle is a bino-like neutralino, and the lightest SUSY particle is the gravitino. The strong production of top squark pairs can produce events with pairs of top quarks and neutralinos, with each neutralino decaying into a photon and a gravitino. The search is performed using a sample of pp collision data accumulated by the CMS experiment at sqrt s = 8 TeV, corresponding to an integrated luminosity of 19.7 fb^{-1}. The final state consists of a lepton (an electron or muon), jets, and one or two photons. The imbalance in the transverse momentum in the events is compared with expected spectrum from standard model processes. No excess event yield is observed above the expected background, and the result is interpreted in the context of a general model of gauge-mediated SUSY breaking, leading to the exclusion of top squark masses below 650—750 GeV.

-In the original version, the phrase “gravitino as the lightest SUSY particle with a bino-like mixing of the neutralino, the next-to-lightest SUSY particle, seems hard to read.

- In the original version, a comma is definitely needed after “19.7 fb^{-1} . Otherwise, the sentence implies that this lumi applies channel by channel. Having both the data sample and the signature in a single sentence seems like too much.

- In the original version, the phrase “gauge-mediated SUSY breaking that leads to the exclusion is grammatically fine, but I think it isn’t quite the meaning that you want. I think there should be a looser connection between the model and the result.

Response: The wording of the abstract is changed as suggested.

1. Introduction

Comment: L6 ***Suggest changing “and the lightest Higgsino […] to “and the Higgsinos […]

As far as I know (e.g., Papucci et al.) all four Higgsinos are expected to be light in natural SUSY. In fact, in the limit that they are pure Higgsino, they are mass degenerate.

Response: Done

Comment: L6-L8 ***I am not sure that I am following the logic of this sentence. It seems to say start with a theoretical motivation and the says that this indicates that there are many searches left to be done at the LHC. To me these are two separately true statements, but the first one does not imply the second one. Also, why are you referring to the little hierarchy problem here, whereas previously you referred to the hierarchy problem?

Here is a suggestion:

In such SUSY scenarios, the fine-tuning required to maintain low mass of the electroweak scale can be avoided, and many searches for light top squarks are being pursued at the CERN LHC.

I have changed the meaning of the last part of the sentence, and here I think that it would be appropriate to reference the top squark searches from ATLAS and CMS more broadly. Our papers allow reinterpretation in different models, so my guess is that their results could be relevant to this case as well.

Response: We have changed the wording.

Response 2: Brian can you look if some appropriate references for top squark searches form ATLAS and CMS and give them to me to enter. I think you already did a search.

Comment: L15

that decays to a photon and a gravitino leading to photons in the final state. → suggest that decays to a photon and a gravitino, leading to photons in the final state.

Response: Done

Comment: L18

“Furthermore, if the top squark is the only colored particle sufficiently light to be produced at the LHC, SUSY production would proceed through pair production of top squarks.

***This is OK, but I don’t see why you need to go this far…if there were other colored SUSY particles light enough to be produced, you would still have top squark pair production. And natural SUSY certainly allows other light-ish colored particles (~t_2, ~b_L, and ~g). The structure of the paragraph controlled by the fact that you start with the neutralino and gravitino and don’t explain the SUSY production process until the end of the paragraph. So I think that the key role of the sentence here is to state the actual production process assumed — you don’t need to assume that it is the only SUSY production process. How about

“Because top squarks are expected to be relatively light in natural SUSY scenarios, we search for top squark pair production, a strong process. [Then as before] Assuming a bino-like NLSP, each top squark would decay to a top quark and a neutralino, with the neutralino decaying to a photon and a gravitino, leading to a ttbar + gamma gamma + pTmiss topology.

Response: Done

Comment: L23 …final state of the ttbar pair that requires the presence → suggest …final state of the ttbar pair, which requires the presence of

To me, this makes more sense as a non-restrictive clause.

Response: Done

Comment: L25 ***“and an enhanced lepton+jets mode in ttbar decays. Not sure what you are saying here…could you please clarify? How is this different from what you just said?

Response: the phrase you point out is redundant and has been removed.

Comment: L27 “that depend on the presence of one or two selected photons in the event → suggest “, depending on the presence of one or two selected photons in the event

Response: Done

Comment: L30 You define "false photons" on L105, so I don’t see why you also need to do that here. I would just end the sentence at “requirements.

Response: Done

2. The CMS detector

Fine.

3. Event and object reconstruction

Comment: L66 “and have transverse momentum → “and to have transverse momentum [need parallel grammar]

The structure of this sentence is a bit odd. It looks like a 3-time list, but “and appears twice. How about

“Photons are reconstructed… , are required to be …, and must have… or “Photons are reconstructed . They are required to be isolated…and to have [no comma].

Response: Sentence has been reworked to address the suggestions.

Comment: L78 “and be → “and to be

Response: Done

Comment: L83-85 problem with parallel structure

“are required to have pT>30 GeV, be within …, and have… → “are required to have pT>30 GeV, to be within…, and to have…

Response: Done

Comment: L85 The phrase “are used to identify extra leptons used to veto… is repetitive. Suggest “are applied to identify extra leptons that are used to veto…

Response: Done

Comment: L88 “thereby increasing sensitivity to signal. → “thereby increasing the signal sensitivity.

Response: Done

Comment: L90 “The efficiency of selection is about… → “The selection efficiency is about…

Response: Done

4. Analysis strategy

Maybe this section should be called “Event selection and analysis strategy ?


The section starts off with a very detailed discussion of triggers, lepton requirements, and photon requirements. It doesn’t seem like a “strategy discussion. I think it could be useful to have a 1-2 sentence overview.

There is a discussion of the trigger pT thresholds for the leptons, but the offline cuts are given in the previous section. Seems a bit odd.

Response: We have changed the name of the section as suggested. We considered moving the trigger requirements for electrons and muons to the previous section but it did not seem to fit there since that deals with object reconstruction not even selection.

Comment: L103 “…more than one photon candidates → “…at least two photon candidates

Response: Done

Comment: L106 “that are used to define two control regions → “and are used to define two control regions

Response: Done

Comment: L107 “one false and no genuine photons passing all requirements → ??? “one false and no genuine photons

Response: Done

Comment: L108 “passing all requirements - again this seems redundant. Or am I missing something?

Response: Unnecessary phrase removed.

Comment: L116 - I don't see anything about GEANT being used to simulate the detector.

Response: Brian, can you see where to add the role of GEANT in simulating the detector for these MC simulations?

Comment: L130 “The Z+jets and Z+gamma events correspond to small backgrounds in the muon+jets channel originating from the negligible misidentification of muons as photons.

It is odd to say that something “small originates from something that is “negligible . This does not sound consistent. How about

“In the muon+jets channel, the background from Z+jets and Z+gamma events is very small [negligible], becaus of the low probability for a muon to be misidentified as a photon. In the electron+jets channel, however, these processes contribute more to the background, especially at low pTmiss, because the probability for an electron to be misidentified as a photon is much higher.

Response: The sentences have been revised as suggested

Comment: L145 “estimate in the number of Z bosons → “estimate of the number of Z bosons

Response: Done

Comment: L146 “to obtain a second scale factor SFegamma to correct the misidentification of electrons as photons → “to obtain a second scale factor, SFegamma, which corrects the MC prediction for the rate of misidentificaiton of electrons as photons

Response: Done

Comment: L156 “each of these SF are listed in Table 1 → “each of these scale factors are listed in Table 1

Response: Done

Comment: Table 1 caption

“Scale factors,…, normalizing Z+jets… backgrounds → “Measured values of the scale factors SFx and SFy, which are used to correct the Monte Carlo predictions for….

Response: Suggested changes on caption made.

Comment: Figure 1 caption

***I am confused about the wording “and (c) has the result of the fit for SF… Maybe “has should be “as ? But the overall wording is awkward. I suggest splitting the discussion of the fit as a separate sentence.

Response: The caption has been reworded to make plane c description clearer

Comment: L181 ***The formula “(1-Data/Background) is awkward. Is there are better way to do this? Do you even need this?

Response: The formula was suggested by the CWR reviewers . Attempts at a statement of what was done were relatively clumsy compared to a simple formula.

5. Results and interpretation

Comment: L194 there is some stray text here: “labelInterpretation .

Response: Latex fixed

L196 “and assumed to be → “and are assumed to be

Response: Done

Comment: L202 The list here is awkward, because there is a sub-list, but only commas are used. Suggest ended sentence after “in MC scale factors. Then start a new sentence

“These include b tagging; electron, muon, and photon identification; and trigger efficiency.

So now you can use the ; for the main list and , for the sublist. This is standard.

Response: Done

Commnent: L204 “shown in Fig. 3 → “as shown in Fig. 3

Response: Done

Comment: ***L207 I don't see anything about whether FastSim or FullSim was used here. Was this privately generated MC?

Response: Brian, what did you use for MC?

Comment: L208 no comma before “and NLO cross sections

Response: Removed comma

Comment: L209 a bit odd to see “top squark written out as text rather than as a symbol. Why not introduce the symbol in the Intro and use it?

Response: Not completely sure what is suggested here. We were told by the Pub chair to use top squark to refer to stops rather than symbols for stops in this paper. This was indicated as standard procedure.

Comment: L213 “are decoupled by setting them to very large masses to force… 
→ “are decoupled by setting their masses to very large values. [then start a new sentence]

Response: Done

Comment: Table 2 caption - "unceraintie" -> "uncertainties"

Response: Done

Comment: Table 3 In expressions like "(460, 175)" need a space after the comma.

Response: Done

Comment; L227 Need to make sure that +- doesn’t separate from 100. Can put the whole thing in math mode.

Response: Done

Comment: L230-L232 It is odd that you do not make any observations or comments about Fig. 4 and Fig. 5.

Response: It was thought that the captions and the plots were sufficient to explain with the conclusions as stated.

Comment: Figure 4 The symbol ~t is used in the figure but not in the text. Actually, it is sometimes used in the figure (in the decay description) and sometimes not (in the inequalities). We need to be consistent in the notation. Note also the x-axis label and the figure caption.

Some symbols seem to be in boldface and others not. I don't see a reason why.

Response: Sasha, can you fix Figure 4 replacing the symbols by top squarks and fix the boldface issue.

******************************************************************************************************************************************************

Comments Set 2: Keith Ulner

type B

Introduction. Are there other relevant searches that you should be citing?

Response: Waiting on Brian to give me a set of references.

Comment -line 16. I don't understand the connection between R parity and strong production. Maybe just drop the "Assuming that R parity is conserved" clause?

Response: The R parity connection is with "pair production", not strong interaction.

Comment: -line 32-35 This sentence is not so clear to me. Perhaps restructure it to say the following. "The normalization of the XXXXXXX background(s) are allowed to float freely in the fit, which helps avoid uncertainty in the tt+jets, tt+gamma, and tt+gamma,gamma production cross sections."

Response: The sentence in question has been restructured. Response 2: You had better check this modified sentence Brian.

Comment -line 58. There's something wrong in the parenthetical list. muons and photons at least should be there, I guess.

Response: Done

Comment -line 66. Should add a reference to something for the photon ID.

Response: Reference 27 for photon reconstruction and ID is a line or two later in the text

Comment -lines 93-95 on the trigger would fit better at the beginning of Sec. 3.

Response: We tried positioning 93-95 st the beginning of section 3 but it fit better in our estimation in section 4 which has been relabeled as Event selection and analysis.

Comment -lines 96-99. Say explicitly that one lepton is required here.

Response:

Comment -lines 96-99. I'd move the sentence about the extra lepton veto to the end of this paragraph.

Response:

Comment -lines 116-129. You should mention GEANT used for the simulation somewhere.

Response:

Comment -line 152. I don't understand "data MC sample." Is it maybe just a typo and should be "data sample?"

Response:

Comment -line 182. Is there a reference for the Kolmogorov-Smirnov test?

Response:

Comment -line 194. Fix the latex here.

Comment -line 205-206. The sentence with the reference to Table 2 should go at the end of the previous paragraph, i.e. at line 202.

Response:

Comment -line 210. I guess "100% bino-like" is meant to signify that the decay is 100% to photon,gravitino. It would be better to also say that explicitly.

Response:

Comment -line 207-216. Give the gravitino mass, too. As it's written now, it looks like it would be decoupled, which certainly isn't what you mean.

Response: Brian, what was the gravitino mass? 1 KeV??

Comment -line 207-216. Mention FastSim, if you are using it (or GEANT if you are not).

Response:

-line 221 "that are integrated over in the analysis" I don't understand this clause.

Response:

type A

Comment -abstract line 3 rewrite as "...with a bono-like neutralino as the next-to-lightest SUSY particle." There is more than one neutralino, so writing "the neutralino" doesn't seem right to me.

Response:

Comment -line 2 remove "is considered to be"

Response:

Comment -line 8 "still remain to be pursued" => "are worth pursuing"

Response:

Comment -line 25 drop ", and an enhanced leptons+jets mode in tt decays." Or else rewrite that to make it more clear what the point is. I don't get what you mean as it is written now.

Response:

Comment -line 30. "false photons" is a strange construction to me. I'd prefer "fake photons," but I'm guessing someone else has already asked to you to change from that. I leave this one up to you at this point.

Response:

Comment -line 59. "PF-particles" => "PF-particle"

Response:

Comment -line 103 "photon candidates" => "photon candidate"

Response:

Comment -line 118. I've never seen LO written as "lowest-order." I think "leading-order" is more common.

Response:

Comment -line 151 "size of" => "statistics available for"

Response:

Comment -line 156 "to each" => "for each"

Response:

Comment -line 164 "distribution" => "shape"

Response:

Comment -Fig. 1 caption "(c) has" => "(c) shows"

Response:

Comment -line 181-182 "(1-Data/Background) percent" => "fractional"

Response:

Comment -line 183. Probably don't need so many significant figures in the 0.6575 number.

Response:

Comment -line 184. "determine uncertainty" => "determine an uncertainty"

Response:

Comment -line 224 "form" => "shape"

Response:

Comment -line 231 "smaller" => "less stringent"

Response:

Comment -line 232 consider adding "with exclusions up to 750 GeV in stop mass."

Response:

Comments Set 3

Comments Set 4

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Topic revision: r4 - 2017-06-04 - BradCox
 
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