bfys-physics June 2013

bfys-physics@nikhef.nl

9 participants
9 discussions

[Bfys-physics] Bfys Meeting Friday 18 january at 9:30 in N328 and on EVO
by Tjeerd Ketel 09 Jun '14

09 Jun '14

Bfys Meeting Friday 18 january at 9:30 in N328 and on EVO* Paper introduction and discussion: 9:30 "A search for D+(s) to pi+mu+mu- and D+(s) to pi-mu+mu+ decays" by Francesco Dettori http://cds.cern.ch/record/1504407 Veldhoven rehearsals: 10:30 "A new window for new physics in Bs decays to two muons" by Rob Knegjens 11:00 "The Bs meson decay in two muons: a search for rare beauty" by Serena Oggero 11:30 "Measurement of the angle gamma in the unitary triangle in time-dependent Bs to DsK decays at the LHCb experiment" by Manuel Schiller The presentations will be available (protected under lhcb, etc.) on the Nikhef agenda page and comments can be directly mailed to the speakers. Best regards, Tjeerd *)Today Vidyo could not provide the same service as EVO in our meeting room at Nikhef, therefore I decided to book this meeting again on EVO. Universe is the community, as LHCb has been removed. As a test we can open a room in Vidyo on Friday at 12:00. ========================================================= http://agenda.nikhef.nl/conferenceDisplay.py?confId=2361 ========================================================= You have BOOKED a meeting in SeeVogh Research Network (http://research.seevogh.com). Title: Nikhef Description: Bfys Meeting 9:30-12:00 Community: Universe Password: n328 Meeting Access Information: - Meeting URL SeeVogh R.N. http://research.seevogh.com/join?meeting=MsMiMI2u2IDnDe999aDt9s EVO International http://evo.caltech.edu/evoNext/koala.jnlp?meeting=MsMiMI2u2IDnDe999aDt9s - Password: n328 - Phone Bridge ID: 627 7875 Password: 6287 =========================================================

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[Bfys-physics] Bfys Meeting Friday 5 July 9:30 in N328 (and Vidyo)
by Tjeerd Ketel 09 Jul '13

09 Jul '13

Dear colleagues, We have 4 papers to comment on and I am looking for volunteers. Please, let me know as soon as possible which paper you would like to introduce and if Friday 5 July would be fine for you. As a first attempt I reserved next week Friday morning for it, but we may discuss one or two papers at a different time if that is more suitable. Best regards, Tjeerd Bfys Meeting Friday 5 July 9:30 in N328 (and Vidyo) 9:30-12 Introductions and short discussions of the following papers (still in order of announcement) 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 Deadline : 09-Jul-2013 LHCb PAPER-2013-034: "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 LHCb PAPER-2013-042: "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 LHCb PAPER-2013-035: "Observation of the decay $B_s^0\to\bar{D}^0\phi$" Link : https://cds.cern.ch/record/1558181 Deadline : 10-Jul-2013 Presentation 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 protected by PIN 1328

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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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[Bfys-physics] Suggested comments
by Hella Snoek 03 Jun '13

03 Jun '13

Hi All, I have received comments from Wouter and Tjeerd (thanks!) and have integrated their comments with mine. Unless someone objects or has additional comments this is what I propose to post around 23:00 this evening. Cheers, Hella ____________________ Dear authors, Congratulations with the very nice analysis and results. Please find below the comments from the Nikhef group. regards, Hella Abstract: 1 fb^{-1} -> 1.0 fb^{-1} The paper: L3: Specify "quarkonia" as "heavy" or even better "charmed". This paper and the "available models" concern only those specific mesons. Replace "can either ... b hadrons" by "can be produced directly, or indirectly via decay of higher excited states (feed down) or via B meson decays". ("either" applies here to three possibilities. Without the "," in "directly, from cascade decays" it would only apply to the last two. Be consequent with writing "feed down".) L7-8: Replace "of the cross-section and the polarisation" by "of the production cross-section and of the polarization of promptly produced charmonium states". Otherwise it is not clear to what "the polarization" applies. L23: Replace "Measurements of the chi_c production and the relative amounts of chi_c1 and chi_c2 spin states have previously been made using different particle beams and energies [8-12]" by "Measurements of chi_c1 and chi_c2 production cross sections for various colliding particles and energies have been reported in" L29: Write "radiative J/psi decay". L30: which -> that L31: Replace "The converted photons are reconstructed using e+ and e- tracks" by "The photons that convert between the vertex detector and the first tracker station before the magnet are reconstructed by the e+ and e- tracks through the magnet". L33: Replace "of converted photons is better than that of calorimetric ones (i.e. non-converted or converted after the dipole such that ... single cluster in the calorimeter)" by "of these "converted" photons is better than that of photons detected as a single cluster in the calorimeter ("calorimetric" photons) without the momentum information of e+ and e- particles". L37: Replace "These two measurements are highly uncorrelated, in particular the uncertainty due to the photon reconstruction as it is based ... reported here" by "The systematic uncertainty due to the photon reconstruction in Ref.[12] is based on calorimetric information and is very different from the present one which is based on track information". L42: 'has never been observed at hadron colliders' -> 'has never been observed before at hadron colliders' L83: - Replace "bremsstrahlung radiation" by "bremsstrahlung". - Replace "the conversions are reconstructed only with tracks ..., ensuring that the photon converts between the downstream end of the VELO and the first tracking station" by "only converted photons are reconstructed with tracks ... to ensure that the photon converts between the VELO and the next tracking station". L90: You use 'y' and later (L. 98) also 'z' but the coordinate system is not defined. We suggest to define this when you describe the LHCb experiment in Sect. 2. L90: - Replace "photons" by "a photon". L91: - Replace "linear extrapolation" by "straight line extrapolation". - Replace "electron track" by "electron (positron) track". L92: - Replace "are selected and their momentum" by "is selected and its energy". - Replace "electron momentum" by "electron (positron) energy from the reconstructed track." L110 and further: We do not understand why you need the cut on 40mm. Since the 2nd vertex will very often be within 40mm it is hard to understand why this rejects more background than data. The PV resolution is 30 micron, so all you are testing here is how well downstream twoprongs can be matched to a PV, which is almost random. Why isn't it enough to require that the converted photon and the J/psi forma good vertex? We are also really puzzled by the valued of your chi2 cuts, which are order 100 per dof. We cannot put those values in the paper, because it can only mean that we try to do something with very poorly calibrated errors. So, please replace with something much vaguer like "We require the jpsi and photon to form a good vertex and that the chi_c candidates points back to a primary vertex." Did you try and understand why you need such a very large chi2 cut to be efficient for signal? It cannot be the j/psi vertex or its IPchi2, because those we understand reasonably well. How are the errors on the parameters of the converted photon determined? L115: lower -> smaller L126: 'of a photon' -> 'for a photon'. This sentence is confusing. Is the total chance of a photon converting before the first tracking station 20%? Please clarify the text. L140: Here and in the rest of the paper J/Psi (and other particles) should be followed by nouns like 'meson', 'hadron' or 'candidate'. L149 and further: The part about the combinatorial background description is very difficult to follow. Why do you use a factor two, is there a specific reason for that? Suggestion for L151 and further: "It is therefore important to reproduce well their angular distribution in order to obtain the correct shape for the invariant mass." -> "In order to correctly reproduce the angular distribution, to obtain the correct invariant mass shape, fake photons are constructed from the selected converted photons in the sample. For each... " L152: add comma between task and fake L230-231: The 3% sounds arbitrary due to the formulation that you use. If you describe the 'other bins' you might want to write. 'The other bins show no significant bias within the 3% uncertainty of the test. A systematic uncertainty of 3% is assigned to all bins.' L281 Section 7: This is a strange section. You describe the chi_{c0} analysis fully, including systematics, efficiency and results in the middle of an ongoing paper. We suggest to either integrate the parts in the rest of the document or move this after the chi_c1/chi_c2 results. L352-353: "This is the first chi_c0 observation at hadron colliders." -> "This is the first observation of chi_c0 mesons at hadron colliders."

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bfys-physics June 2013