http://cms.cern.ch/cds/BPH-13-007 **Commenti dell'ARC chair da tenere in considerazione nei commenti che mandiamo** Dear colleagues, Many thanks for your participation to the institutional review of BPH-13-007. You should be aware that the institutional comments in CDS and their responses will be also posted in a twiki page shared with LHCb. This twiki page is open to both CMS and LHCb general mailing lists: https://twiki.cern.ch/twiki/bin/view/Sandbox/BsmumuCombComments Joel Butler for the authors is taking care of filtering the comments that are CMS-specific or may be be perceived as offending for LHCb. There are very few such comments. Please tell us if you wish that your comments -- or part of your comments -- remain CMS-internal, or if you want to rephrase some of them before sharing them with LHCb, or if you want your name to be replaced by your institution, or if you have any other concern about sharing your comments with LHCb. Best regards, Gautier **Commenti dell'ARC chair da tenere in considerazione nei commenti che mandiamo** Dear Institutional Representatives for the IRC of BPH-13-007, thank you for accepting to serve as Institutional Review Committee on the paper draft for BPH-13-007 entitled "Observation of the rare B0s -> mu+mu- decay from the combined analysis of CMS and LHCb data" to be submitted to Nature. For the preparation of your comments, I wanted to point out a few conditions that went along with the approval of the analysis yesterday as well as a few wording changes on the paper draft that were the result of additional negotiations on the text with LHCb. Please keep these issues in mind when composing your comments: * Outcome of the approval meeting: 1) Use the "S/S+B weighted all categories" mass plot in the paper and the "six best categories" in the extended session (swap Figure 2 with Extended Data Figure 2) and modify the text accordingly 2) In all 2d plots (Figure 3 and Extended Data Figure 6) remove the 5 sigma and 6 sigma contours (or smooth them) 3) Include the individual BR results from CMS and LHCb in the extended data section with their uncertainties but without significances 4) In the summary part of the paper emphasize the “2 sigma compatibility” with SM (without reference to the 3.0 sigma “evidence”) 5) As a suggestion the major emphasis should be put on the Feldman-Cousins 3.0 sigma result instead of the 3.2 sigma figure based on the delta-log-likelihood * Wording changes agreed upon with LHCb spokes: @L23: Instead of "It also produces the first 3 standard deviation evidence for B0 -> mu+mu- decay." new text: "It also produces 3 standard deviation evidence for an excess of events in the search for B0 -> mu+mu- decays." @L204: Instead of "It also produces the first $3\sigma$ evidence for B0 -> mu+mu decay." new text: "It also produces $3\sigma$ evidence for an excess of events in the search for B0 -> mu+mu- decays." Thank you for your attention to this matter. We are looking forward to receiving your CWR comments by the deadline of Sept 8, 2014 (sharp). Best, Manfred (ARC chair). **Commenti di Linda F** 13-15: If different rates... it would prove ==> *Any divergency from these predictions* would prove... 16: LHC had the opportunity ==> LHC *has* the opportunnity 23: to date ==> credo sia implicito 23: it also produces ==> it also *yields* (metterei un sinonimo perché c'è una ripetizione) 35-36: neglected but now had to be included ... results ==> neglected*, in order to* match the more precise experimental results 44-45: Many theoretical ... short-coming ==> secondo me c'è qualcosa che non funziona nella costruzione della frase 45: short-coming ==> shortcoming 46: SM predictions to guide ==> SM predictions*,* to guide 48-49: B0 mesons consisting ... d-quark into a dimuon ==> B0 mesons*, *consisting ... d-quark*, *into a dimuon 53: internal loops as ==> internal loops*, *as 56-57: The SM predictions are ... SM predictions ==> The SM predictions are: B()=... and B()=... *, very far, prior to the start of LHC, from *the experimental upper limitis 65-66: uncertainties, would ==> uncertainties would 68: predicted in the SM ==> predicted* by *the SM 69: beyond the SM ==> beyond *this theory* 80-81: toglierei l'ultima frase 84: and and ==> and 85: strategies are different and complementary in the two experiments ==> strategies are different and complementary. (implicito) 105: are expected for the two together ==> are expected. (di nuovo implicito) 132: key ==> *the* key 174: S/(S+B) where S and B are the number of expected signal assuming SM rate, and background events for a given category ==> S/(S+B)*, *where S and B* are the number of expected signal and background events*. 176: Fig. 2 where ==> Fig 2*, *where 180: LHCb can be ==> LHCb*, *can be 183: deviations, σ, and ==> deviations* (σ) *and 186: Fig 3 where ==> Fig 3*, *where 221: in the data while ==> in the data*, *while 227: vertex; and variables ==> vertex; variables 234: published results each experiment ==> publish results*, *each experiments **Commenti di Gian Luca P** Line 30: Could be useful specify that the observation is a consequence of a 5 sigma statistical significance? e.g. ...decay could be observed. -> ...decay could be observed reaching 5 sigma statistical significance needed to declare the discovery. Line 84: and and -> and Line 90: ...with high mass, 100 GeV to a few.. -> ..with high mass, from 100 GeV to a few.. Line 92: CMS is designed to be able to study B decays -> CMS is automatically designed to be able to study B decays . Line 93: they instrument complementary geometrical volume -> they work on complementary geometrical volume. I didn't find the use of instrument as a verb anywhere. >From 151 to 155: I will reconstruct the sentence in order to be more immediately understood. Both analyses include in the MVA the displacement between the production and decay vertices of the B meson to discriminate against combinatorial background. Therefore the efficiency as a function of lifetime has a model dependent correction [22], which is estimated through simulations assuming SM dynamics. -> Since both analyses include in the MVA the displacement between the production and decay vertices of the B meson the eefficiency, as a function of lifetime, has a model dependent correction [22], which is estimated through simulations assuming SM dynamics. (Or something like that...) Line 161: I guess the data-taking periods means to 2011 2012 and consequently the energy in the centre-of-mass. I will replace data-taking periods with the energy in the centre-of-mass. Figure 3: I will add the SM prediction also to the two plots on the left as in Figure 4. Line 396: Same problem as line 93. Extended data figure 6: I will add the SM model prediction. **Commenti di Stefano A.** The Torino group wishes to congratulate the authors for this achievement and for the very well written paper. Below we have a few small comments. Type B 1. There is no mention on how the backgrounds are treated in the extraction of the BR until L484. We suggest to move the explanation to the "analyses" section. 2. In the introduction, the shortcomings of the SM are described at length (L40-47). This puts the reader in expectation of a measurement in disagreement with it. Unfortunately this analysis does not show any evidence of deviation from the SM. We therefore suggest to give less emphasis to the shortcomings and perhaps higlight the successes of the SM ! Type A L26-30 : consider removing from “The LHC experiments “ to the end of the paragraph. The point is already made in L209 and it does not say anything about the content of the present paper, so there is no need to make it in the summary. L41: keeping in mind comment 1. above, we don’t understand the choice of references here. L41 says “recent years”, yet Refs [6,7] are from 1995. Perhaps in L41 [6,7] should be replaced by [8], and [6,7] should be moved to right after “(CP violation)”. L46: replace “mounted “ with prepared/designed/devised/envisaged L50: a large space is present between the period and “In the SM" L53: remove the word “complicated” L53: "diagrams with" -> diagrams featuring L57: “there was a large gap” -> The precision achievable by experiments was too low to enable a confirmation of SM predictions L84: “deviations due to physics outside of it” -> deviations from it L85-L92: wonder if this blabla on the strategies for the search for NP isn’t a bit outside the scope of the present work L118: “multivariate analysis (MVA) discrimination variables that combine ..” The variables are just variables, not MVA variables. Suggest : “m_mumu, and a set of kinematic and topological variables combined using MVA analysis techniques.” . Optionally add “These techniques allow superior S/B discriminating power and and efficiency “ L123-126: consider removing “The invariant mass … not detected” L126: "There is also “ -> “Another source of " L131: remove the word “dangerous” L135: “direction of the muons relative to the beam direction” ->”relative to the beam axis" (avoid repetition) L258: the link of Ref [6] is broken L262: “A&A” -> replace with suitable abbreviation L288: link of Ref [19] does not work L382: "to a few tens of mm” : most lifetime plots have ranges up to a few mm, not tens of mm. One can argue that a tiny fraction of B will fly for “few tens of mm” (= centimeters), yet we wonder if the words “tens of” are a typo. L397: we believe the symbol for radian is “rad” rather than “r” L408: “translates to” -> “translates into” L492: mixing degrees and radians sounds awkward. Symbol for radians is “rad” L433: “at the particle momenta in this analysis” -> for the momentum range of interest for this analysis L441: “look for heavy objects decaying into two muons” -> remove the word “two” L450: reference -> references L521: References -> Refs. L528: “this channel’s efficiency” -> the efficiency of this channel **Fine commenti Stefano A. **