bfys-physics

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520 discussions

[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] Master Thesis Presentation of Jesse Mesman
by Wouter Hulsbergen 27 Jun '13

27 Jun '13

Dear all, On behalf of Jesse, I would like to invite you to his master thesis presentation tomorrow at 1pm in room *H220*. Please see below for details and abstract! Cheers, Wouter > > Dear all, > > I am very happy to announce that I will be doing my master thesis > presentation this friday the 28th at 13:00 in room H220 at Nikhef. The > abstract is down below and I hope to see you all there! > > Cheers Jesse > > If the weak phase in $B_{s}^{0}-\overline{B_{s}^{0} > }$ mixing (2$\beta_{s}$) is found to be significantly different from the > Standard Model prediction it would be a clear sign of new physics. One > possible method of determining this angle is through the $B_{s}^{0} \to > \overline{D^{0}}K^{0}_{S}$ decay. This specific decay channel is chosen > due to its similarity to the $B_{s}^{0} \to J/\psi\phi$ decay which is > normally used for determining $\beta_{s}$. To investigate this > possibility the $B_{s}^{0} \to \overline{D^{0}}K^{0}$ branching fraction > is determined relative to the known $B^{0} \to \overline{D^{0}}K^{0}$ > branching fraction. The $B^{0}_{s} \to \overline{D^{0}}K^{0}_{S}$ decay > is searched for in data samples of 1.0 and 2.0 fb$^{-1}$ collected with > the LHCb detector during 2011 and 2012 respectively. A significant > signal is observed and the branching fraction ratio is determined to be > $\frac{BF(B^{0}_{s} \to \overline{D^{0}}K^{0}_{S}, \overline{D^{0}} \to > K\pi, K^{0}_{S} \to \pi^{+}\pi^{-})}{BF(B^{0} \to > \overline{D^{0}}K^{0}_{S}, \overline{D^{0}} \to K\pi, K^{0}_{S} \to > \pi^{+}\pi^{-})}=4.95 \pm 0.81$ (stat) $ \pm$ $0.38$ (syst). This > corresponds to a branching fraction of $BF(B^{0}_{s} \to > \overline{D^{0}}K^{0})=(2.6 \pm 0.6$ (stat) $\pm$ $0.2$ (syst) > $)\cdot10^{-4}$. This is the first observation of this decay channel. > The $B^{0}_{s} \to \overline{D^{0}}K^{0}_{S}$ decay channel is probably > not a suitable channel for $\beta_{s}$ determination and time dependent > CP asymmetry measurements because insufficient signal is found in this > paper and due to the lower proper time resolution of the decay channel > in comparison to $B_{s}^{0} \to J/\psi\phi$.

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[Bfys-physics] Bfys Meeting Friday 14 June 10:00 in N328 (and Vydeo)
by Tjeerd Ketel 20 Jun '13

20 Jun '13

Bfys Meeting Friday 14 June 10:00 in N328 (and Vydeo) 10:00 Introduction and short discussion by Francesco Dettori of LHCb PAPER-2013-030: "Search for the lepton-flavour violating decays $B_{s}^{0} \to e^{\pm} \mu^{\mp}$ and $B^{0} \to e^{\pm} \mu^{\mp}$" Link : http://cds.cern.ch/record/1553520 Deadline : 19-Jun-2013 Presentation can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2525 and will be protected by lhcb, etc. Vydeo link in Nikhef Bfys Meeting at LHCb meetings of the week after (21 June - to save me a new name): https://indico.cern.ch/conferenceDisplay.py?confId=255161 protected by PIN 1328 Best regards, Tjeerd

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[Bfys-physics] Master Thesis Presentation
by Suzanne Klaver 18 Jun '13

18 Jun '13

Dear all, I am very happy to tell you that I will be presenting my master thesis on Thursday June 20! I have searched for long-lived neutralinos and, unfortunately, not found any. Nevertheless, I would very much appreciate your presence during the presentation at 15:00 in H331 at Nikhef. Cheers, Suzanne *A Search for Long-Lived Neutralinos at LHCb:* Supersymmetric (SUSY) extensions of the Standard Model (SM) predict the existence of neutral fermions called neutralinos. A search is performed for neutralinos in the scenario of an R-parity violating model, in which supersymmetry is broken through gravitational interactions (BRpV-mSUGRA). The LSP is the neutralino and has a 71.2 ps lifetime, decaying into SM particles. We present the search for long-lived neutralinos using the 2011 data set of the LHCb detector at CERN in pp collisions at \sqrt{s}=7 TeV, with an integrated luminosity of 1.0 fb^{-1}. We look for a signature with a displaced vertex with two jets and a muon. By performing a cut-based analysis, an upper limit is set on 2 \times \sigma \times BR < 3.3 pb at 95% confidence level, with a relative systematic uncertainty of 8.3%. This corresponds to approximately 7 times the predicted SUSY cross section.

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[Bfys-physics] My comments on the emu paper
by Patrick Koppenburg 14 Jun '13

14 Jun '13

Dear Francesco, Here are my comments on the emu paper (not about the bird). Francesco, could you please check what was the original notation in the paper? In 1974 they certainly did not write M_LQ(B->emu) as the B was not even predicted. To me it looks like the mass is a property of the decay, while it's the other way round. In any case, we agreed that should be explained better. The text from the justification could be used. My personal opinion is that we should not force them to go to a long paper. But some things can be shortened, others need expanding. 175: the supersymmetry models -> sumpersymmetric models (remove the) 194: is the mention of 2 fb^-1 meaningful if the energy and collision is not given? I'd remove. 204-207: That should go much later. But here one should explain the strategy, introecue the concept of normalisation and control channels. Else the rest is really hard to read. 244: B is undefined. 246: bremsstrahlung 254: $b$-decays 256-259: This is just wrong 301: invariant mass for background? 308: in 256 you said B->Kpi 330: It depends on event multiplicity and you use nSPD as a measure of it. But the signal shape does not depend on nSPD. Replace by event multiplicity everywhere. 358-363: remove and replace by a mass plot 368: fluctuating with toy experiments -> toy experiments fluctuating 381: why do you need f_u ? It only becomes clear later, write it there. 399: Use trigger paper instead of [30]. 407: This sentence repeats the one in 282. 413: are the signal regions defined? 451-453: Move that to 442. 469-471: repeats 456 473: remove carefully 513: do you need to give the B masses? 524: ... and the Z and the top? Fig 1 could go to additional material and be replaced by a mass plot. Cheers, Patrick -- ======================================================================== Patrick Koppenburg Nikhef, Amsterdam http://www.koppenburg.org/address.html

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[Bfys-physics] Fwd: LHCB-PAPER-2013-028-001-COMMENT-010 (a comment has been made on your comment)
by Hella Snoek 12 Jun '13

12 Jun '13

Hi All, Please find the answers to our comments we made to the Chi_c paper in the link below. Cheers, Hella Begin forwarded message: > From: CERN Document Server Submission Engine <cds.support(a)cern.ch> > Subject: LHCB-PAPER-2013-028-001-COMMENT-010 (a comment has been made on your comment) > Date: June 12, 2013 3:21:50 PM GMT+02:00 > To: <hella.snoek(a)cern.ch> > > Dear LHCb Colleague, > The comment (LHCB-PAPER-2013-028-001-COMMENT-005) that you made on LHCB-PAPER-2013-028-001 > (entitled: 'Measurement of the relative rate of prompt $\chi_{c1}$, $\chi_{c2}$ and $\chi_{c0}$ production at $\sqrt{s}=7$\,TeV') has itself been commented on by Edwige Tournefier [CERN - PH/ULB] (tournefi(a)lapp.in2p3.fr). > > This new comment (LHCB-PAPER-2013-028-001-COMMENT-010) may be seen at > http://cds.cern.ch/record/1554788 > > > Best regards, > The CERN Document Server Server support Team

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[Bfys-physics] Fwd: LHCB-PAPER-2013-023-001-COMMENT-012 (a comment has been made on your comment)
by Jeroen van Leerdam 06 Jun '13

06 Jun '13

The B0->J/psiK*0 angular analysis proponents responded to our comments. They are completely ignoring everything we said. Should I insist on implementation of some of the comments or do we agree with what they say here? Jeroen -------- Original Message -------- Subject: LHCB-PAPER-2013-023-001-COMMENT-012 (a comment has been made on your comment) Date: Wed, 5 Jun 2013 16:09:16 +0200 From: CERN Document Server Submission Engine <cds.support(a)cern.ch> To: <jeroen.van.leerdam(a)cern.ch> Dear LHCb Colleague, The comment (LHCB-PAPER-2013-023-001-COMMENT-006) that you made on LHCB-PAPER-2013-023-001 (entitled: 'A Measurement of the polarisation amplitudes in $B^0 \to J/\psi K^{*}(892)^{0}$ decays') has itself been commented on by Alexander Markus Bien [CERN - PH/ULB] (abien(a)physi.uni-heidelberg.de). This new comment (LHCB-PAPER-2013-023-001-COMMENT-012) may be seen at http://cds.cern.ch/record/1553550 Best regards, The CERN Document Server Server support Team

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