bfys-physics

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520 discussions

[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] Bfys Meeting Friday 31 May at 10:00 in N328 (and Vydeo)
by Tjeerd Ketel 30 May '13

30 May '13

Bfys Meeting Friday 31 May at 10:00 in N328 (and Vydeo) 10:00 Introduction and short discussion by Vasileios and Jeroen of LHCb PAPER-2013-023: "A Measurement of the polarisation amplitudes in $B^0 \to J/\psi K^{*}(892)^{0}$ decays" Link : http://cds.cern.ch/record/1548303 Deadline : 04-Jun-2013 Presentation can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2519 and will be protected by lhcb, etc. Vydeo link in Nikhef Bfys Meeting at LHCb meetings of the week https://indico.cern.ch/conferenceDisplay.py?confId=255161 protected by PIN 1328 Best regards, Tjeerd

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[Bfys-physics] Tuesday meeting by EVO at Nikhef in N328
by Tjeerd Ketel 28 May '13

28 May '13

LHCb Tuesday meeting by EVO at Nikhef in N328 Dear all, You can follow the EVO session of the Tuesday meeting from 14:00 h in N328 this afternoon. Best regards, Tjeerd ---------- Forwarded message ---------- Date: Mon, 27 May 2013 14:20:55 +0000 From: Roger Forty <Roger.Forty(a)cern.ch> To: "lhcb-general (LHCb General mailing list)" <lhcb-general(a)cern.ch> Subject: Tuesday meeting tomorrow: unusual room! Dear colleagues, We will have a Tuesday meeting tomorrow, but please note it will be held in 32/1-A24 (not the usual room). Starting at 14:00 CET, Vidyo available: https://indico.cern.ch/conferenceDisplay.py?confId=229868 Paula will present ideas for enhancing forward physics in LHCb – this is to complement the earlier presentation by Andrei and Nicola (that concerned sterile neutrino searches) and will instead cover the other possibilities for enhancing our forward physics, that may be feasible on a shorter timescale. Then there will be a short report on the changes to the J/psi polarisation analysis that happened between the approval and the first circulation of the draft, and an approval to go to paper for the B-> pph analysis. Hope to see you there, Roger

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[Bfys-physics] Summary of the Bfys meeting on 24 May
by Tjeerd Ketel 24 May '13

24 May '13

Summary of the Bfys meeting on 24 May ===================================== News (Marcel): - Jeroen van Tilburg has obtained a Vidi grant to work with LHCb. He will probably start in September for Nikhef. - Alexandr defended his PhD Thesis very well yesterday at the VU University. - The VELO workshop this week at Nikhef on the Technology Choice for the LHCb Upgrade was fruitfull and well organized. - At the LHCb week at CERN starting June 3rd the new physics coordinator will be elected. One of the candidates is Patrick. - The Bfys workshop from 24-26 June in Renesse is organized by Patrick and Gerhard. Please, respond to the questionaire. - Vasileios and Jeroen will take care of the introduction and discussion of LHCb-PAPER-2013-023 on Friday 31 May 10:00 in N328. "A Measurement of the polarisation amplitudes in $B^0 \to J/\psi K^{*}(892)^{0}$ decay"" Introduction and discussion of LHCb-PAPER-2013-028 (Hella): Hella introduced the paper and there was a discussion about the applied cuts and the treatment of the background. Hella will collect the comments and upload them at CDS this evening as the deadline is today May 24st.

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[Bfys-physics] Bfys Meeting Friday 24 May at 10:00 in N328 (and Vydeo)
by Tjeerd Ketel 23 May '13

23 May '13

Bfys Meeting Friday 24 May at 10:00 in N328 (and Vydeo) Presentation at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2505 protected by lhcb etc. Vydeo link at https://indico.cern.ch/conferenceDisplay.py?confId=252954 proteced by PIN 1328 10:00 News Marcel Merk 10:15 Introduction and schort discussion by Hella Snoek: PAPER-2013-028 : Measurement of the relative rate of prompt $\chi_{c1}$, $\chi_{c2}$ and $\chi_{c0}$ production at $\sqrt{s}=7$\,TeV Link : http://cds.cern.ch/record/1546695 Deadline : 24-May-2013 Best regards, Tjeerd Next week 31 May we will discuss another paper: LHCb PAPER-2013-023: A Measurement of the polarisation amplitudes in $B^0 \to J/\psi K^{*}(892)^{0}$ decays Link : http://cds.cern.ch/record/1548303 Deadline : 04-Jun-2013

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[Bfys-physics] Thesis colloquium
by Jacco de Vries 23 May '13

23 May '13

Dear all, I am glad to announce the date of the colloquium of my master thesis. You can (hopefully) see the results of all the questions I have been bothering you with in the last few months at 9:30, May 23, in room N328 (Nikhef). The title will be "Search for the decay Bc -> Bs Pi". Your presence will be highly appreciated! Until then, Jacco

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[Bfys-physics] Fwd: Stoomboot upgrade re-reminder
by Marcel Merk 21 May '13

21 May '13

Dear group members, Please take note of the following announcement of Jeff Templon w.r.t. stoomboot: ---------- Forwarded message ---------- From: Jeff Templon <templon(a)nikhef.nl> Date: 21 May 2013 12:06 Subject: Stoomboot upgrade re-reminder To: Paul de Jong <h26(a)nikhef.nl>, Raimond Snellings < Raimond.Snellings(a)cern.ch>, Marcel Merk <marcel.merk(a)nikhef.nl>, Jo van den Brand <jo(a)nikhef.nl>, Charles Timmermans <c.timmermans(a)hef.ru.nl>, Patrick Decowski <decowski(a)nikhef.nl>, Eric Laenen <t45(a)nikhef.nl>, Niels van Bakel <nielsvb(a)nikhef.nl>, Aart Heijboer <aart.heijboer(a)nikhef.nl> Cc: Ronald Starink <ronalds(a)nikhef.nl>, Ton Damen <tond(a)nikhef.nl>, Wim Heubers <wimh(a)nikhef.nl> Dear Users and Program Leaders, I send this mail to remind you about the upgrade of the glusterfs file system that will take place from 27 til 29 May 2013. During this upgrade, the glusterfs file system, and stoomboot compute facility (both batch and interactive) nodes will be completely unavailable. Batch submissions will be disabled starting a couple of days beforehand, to ensure that all running jobs will complete before the morning of 27 May. I remind you as well that there is no backup of the glusterfs file system. We do not *expect* data loss as a result of the upgrade, however we cannot exclude the possibility. Thus we recommend that you make a copy, somewhere else, of files that are absolutely critical (i.e. cannot be easily regenerated). If you do not have enough space on places like /project or your own home directory to do this, please contact the grid group (via grid.support(a)nikhef.nl). Note: we don't have enough space to back up everything. JT

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[Bfys-physics] Bfys meeting today and next week
by Tjeerd Ketel 17 May '13

17 May '13

Dear all, The meeting of this morning started 30 minutes late due several reasons: - I created the entry in the agenda in the wrong catogery, TEST, as I got lost in the other possible choices. Therefore, the entry did not appear on the LHCb agenda. - The group email (bfys-group and bfys-physics) is sometimes very slow at Nikhef. I thought it worked because I got my email with the proper confId, but that was the reply to me as sender, not as group member. - Calling from the Polycom did not work, as all 4 gateways I had on my list were repoting busy. - Fortunately, I could add the Polycom as a participant by typing its IP-address 192.16.192.68 for the one in N328. - In the mean time Antonio sent a few of you the proper confid number. Diego presented the features of the Lambda_B paper and his comments were also discussed. Please, sent an email to Diego with your comments, so that he can add them to his list today. Marcel congratulated Diego with winning the 2013 Young Experimental Physicist Prize. He will certainly be busy with that the coming days. Next week Friday 24/5 Hella Snoek will introduce PAPER-2013-028: Measurement of the relative rate of prompt $\chi_{c1}$, $\chi_{c2}$ and $\chi_{c0}$ production at $\sqrt{s}=7$\,TeV Link : http://cds.cern.ch/record/1546695 I entered this 24/5 meeting on the LHCb agenda for its Vidyo link: https://indico.cern.ch/conferenceDisplay.py?confId=252954 Best regards, Tjeerd

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[Bfys-physics] Bfys Meeting Thursday 16 May at 16:00 in N328 (and Vydeo)
by Tjeerd Ketel 16 May '13

16 May '13

Bfys Meeting Thursday 16 May at 16:00 in N328 (and Vydeo) 16:00 Introduction and schort discussion by Diego Martinez Santos: PAPER-2013-025 : Measurement of the differential branching fraction for the decay $\Lambda^0_b\to\Lambda\mu^+\mu^-$ Link : http://cds.cern.ch/record/1546208 Deadline : 17-May-2013 Best regards, Tjeerd

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[Bfys-physics] Unblinding of Bc -> Bs Pi
by Jacco de Vries 15 May '13

15 May '13

Dear all, We would like to share with you the first glimpse of the unblinded Bc -> Bs Pi, using Bs -> Ds Pi. Under study is the partially reconstructed contributions (Bs* pi), (Bs rho). For 2011+2012, the significance at this point is 4.1 sigma (excluding systematics). Thanks, also on behalf of Niels, Jacco

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