bfys-physics July 2013

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[Bfys-physics] Reminder Bfys paper discussion started in H311 now
by Tjeerd Ketel 09 Jul '13

09 Jul '13

Reminder Bfys paper discussion started in H311 now

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[Bfys-physics] Comments on BDphi
by Veerle Heijne 07 Jul '13

07 Jul '13

Dear all, Thank you for sending your comments. I added the issues raised in the meeting. If you have any remaining comments, please send them to me before tomorrow, Tuesday 9 July. Cheers, Veerle Comments on "Observation of the decay Bs -> Dphi" === Title/Abstract: === As a byproduct of the analysis of the normalisation sample, you also give an measurement of the Bs->DbK*b/B->DbK*b ratio of branching fractions, but this is not reflected in the title. That update might therefore go by unnoticed, which would be a pity. Why not: Observation of the decay Bs->Dbphi and updated of the Bs->DbK*b branching fraction. === Introduction: === The current description of the physics case is misleading. As written, it is suggested that by simply collecting a larger sample of Bs->Dbphi one will be able to measure the CKM angle gamma unambiguously, which is not the case. In fact, the mode Bs->Dbphi itself is not sensitive to gamma. One needs the combined information from Bs->Dbphi and Bs->Dphi to extract gamma and in addition also Bs->D(CP)phi to get an unambiguous solution. We think the presentation of the physics case would benefit: - when showing Feynman diagrams - from a discussion of the modes involved and their differences - from a clear explanation of which modes you are and are not measuring, and why. [Are you distinguishing between the D and Dbar? Why is Bs->Dphi not measured?] As this is only a branching ratio measurement, some of the details regarding the determination of gamma [like time-integrated vs time-dependent] could be left out and/or replaced by references only. L.29: eigenstates L.33: "sufficient number of different D final states" could you say how many? === Event Selection: === L. 69: "high sum of the pt of the tracks", could you specify the cut more precisely, or reference to the trigger document [12] which has the required information on the topo lines? L. 89: For the cut on the flight distance of B->Dbar K*, you probably corrected for the acceptance. How large was this correction? L.122: larger than 0.2 is irrelevant to the reader as no distributions are given. Please remove. L.124: which assumptions on the BF? Why did you not use the Punzi FoM that avoids the problem? Line 123: Why did you chose S/Sqrt(S+B) as the optimisation criteria. The Punzi FoM is better suited for optimising for first observations. Line 124: Please give the "assumptions on the decay branching fraction". Line 126: Please specify what you define as the signal region. Is it the whole mass range 5150 to 5600 MeV? === Signal Yield: === Figure 2: - Why are there no red data points between -0.4 and 0.3? If the cut at 0.4 is already applied, you would not expect to see an event at 0.3. - If bins with zero events where suppressed, why is there a partial red line in the -0.3 to -0.2 bin? - the difference between the red/blue is very difficult to distinguish in a black and white printout. Can the colors be changed? L.133: You decide not to use the information of whether you have a DbarK* or a DbarK*bar final state and hence are loosing information. With that info you would have 2 mass plots with the same B, resp Bs signal but half the background. Why don't you do that? Figure 1: - Bs->DbarK*bar (bar missing) - The fit for the partially reconstructed background in pink does not look very convinding. Maybe the RooKeysPdf tuning is too fine? L.173: is -> are L.201 and later : ^{bkg} -> ^{\rm bkg} Line 164: Change "Figure" to "Fig." Line 203: Does this result on fs/fd already contain the latest improvements from CLEO-c? === Systematic uncertainties: === L.219: contribution->'contributions' or 'the contribution' L.226: could you explain why you have a fit bias? L.237-242: you account for DCS decays but not for double mis-ID which give you a broader D mass. How are they treated? Line 237: It would be helpful to write (part of) the information in this paragraph already in the introduction. === Results and Conclusions: === - Line 246+9: Change reference [20] to [8] as the LHCb result is the only entry in the PDG. - f_s/f_d should be in math mode. Are you using the latest error with the new CLEO measurement? - "... compared to a previous measurement [20]" : If it's one measurement cite it and not the PDG. === References: === Line 266: The arxiv link is broken. Remove "hep-ph/"

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[Bfys-physics] B->K*mumu paper
by Marcel Merk 05 Jul '13

05 Jul '13

Dear bfys-physics friend, This is to let you know that I collect comments to the paper below. To stimulate you to read it: we claim that the probability that the measurement is consistent with the Standard Model is only 0.5%. A local discrepancy of 3.7 sigma is observed. LHCb PAPER-2013-037: "Measurement of form factor independent observables in the decay $B^0\to K^{*0}\mu^+\mu^-$" Link : https://cds.cern.ch/record/**1557918<https://cds.cern.ch/record/1557918> Deadline : 09-Jul-2013 best regards, - Marcel

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[Bfys-physics] Dphi paper
by Patrick Koppenburg 05 Jul '13

05 Jul '13

Dear Veerle, Here are my comments on the Dphi paper. L.29: eigenstates L.33: "sufficient number of different D final states" could you say how many? L.122: larger than 0.2 is irrelevant to the reader as no distributions are given. Please remove. L.124: which assumptions on the BF? Why did you not use the Punzi FoM that avoids the problem? L.133: You decide not to use the information of whether you have a DbarK* or a DbarK*bar final state and hence are loosing information. With that info you would have 2 mass plots with the same B, resp Bs signal but half the background. Why don't you do that? Fig. 1: Bs->DbarK*bar (bar missing) L.173: is -> are L.201 and later : ^{bkg} -> ^{\rm bkg} L.226: could you explain why you have a fit bias? L.237-242: you account for DCS decays but not for double mis-ID which give you a broader D mass. How are they treated? Section 5: f_s/f_d should be in math mode. Are you using the latest error with the new CLEO measurement? "... compared to a previous measurement [20]" : If it's one measurement cite it and not the PDG. Cheers, Patrick -- ======================================================================== Patrick Koppenburg Nikhef, Amsterdam http://www.koppenburg.org/address.html

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[Bfys-physics] Bfys Meetings Friday 5 July and Tuesday 9 July
by Tjeerd Ketel 02 Jul '13

02 Jul '13

Dear colleagues, I reserved Friday morning and early afternoon 5 July for two papers. The other two papers will be discussed at Tuesday morning 9 July. A long meeting on Friday morning is not possible due to a meeting of the permanent staff at 9-10h, the colloquium of Max Baak at 11h, and the VELO meeting at 14h. Please, send your comments to the speaker of the paper. Best regards, Tjeerd Bfys Meeting Friday 5 July 10-11h in N328 (and Vidyo) LHCb PAPER-2013-035 by Veerle Heijne "Observation of the decay $B_s^0\to\bar{D}^0\phi$" Link : https://cds.cern.ch/record/1558181 Deadline : 10-Jul-2013 13-14h in H331 !!! (and Vidyo) LHCb PAPER-2013-037 by Marcel Merk "Measurement of form factor independent observables in the decay $B^0\to K^{*0}\mu^+\mu^-$" Link : https://cds.cern.ch/record/1557918 Deadline : 09-Jul-2013 Bfys Meeting Tuesday 9 July 10-11h in N328 (and Vidyo) LHCb PAPER-2013-034 by Tjeerd Ketel "Branching fraction ratio and $CP$ asymmetry measurements of the $B^+ \to K_S^0 \pi^{+}$ and $B^{+} \to K_S^0 K^+$ decays" Link : https://cds.cern.ch/record/1557920 Deadline : 09-Jul-2013 11-12h in N328 (and Vidyo) LHCb PAPER-2013-042 by Rob Lambert "First observation of the decays $B_s^0 \to K_S^0 K^\pm \pi^\mp$ and $B_s^0 \to K_S^0 \pi^+ \pi^-$ and branching fraction measurements of $B_{(s)}^0$ decays to $K_S^0\pi^+\pi^-$, $K_S^0K^\pm \pi^\mp$ and $K_S^0 K^+ K^-$ final states" Link : https://cds.cern.ch/record/1558155 Deadline : 10-Jul-2013 Presentations can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2535 and will be protected by lhcb, etc. Vidyo link in Nikhef Bfys Meeting at LHCb meetings of the week on Friday 21 June 2013 (our previous meeting!!!) protected by PIN 1328. https://indico.cern.ch/conferenceDisplay.py?confId=255991 Best regards, Tjeerd

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bfys-physics July 2013