bfys-physics

bfys-physics@nikhef.nl

520 discussions

[Bfys-physics] Last two postdoc seminars tomorrow: friday
by Marcel Merk 10 Mar '11

10 Mar '11

Dear friends, Tomorrow (friday) we will have the (for now) last two candidates for a postdoc position visiting us and giving a seminar. The first is Manuel Schiller at 10h30 in N328: "Track reconstruction and towards first LHCb results" Abstract: In his seminar Manuel will discuss trackfinding pattern recognition studies, the K_s analysis and work on the proper time resolution in B_s ---> D_s(K K pi) pi in 2009. The second is Chris Thomas at 14h30 in H220: The title of my talk will be "Measurements of gamma using B->DK and the key role of charm physics inputs". The abstract is: "The CKM angle gamma is currently the least constrained of the angles of the b-d unitarity triangle. Analysis of B->DK decays is a very promising method to determine gamma more precisely. In this talk I present the current status of such analyses, including the prospects for a measurement of gamma at LHCb. I also outline the importance of external inputs from charm physics, in particular focusing on the measurement of the (D0,D0bar)->KShh strong phase difference at CLEO-c." I realise that we had an intensive program with many talks and meetings, but your presence is highly appreciated at these seminars. So I hope to see you all there, best regards, - Marcel

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[Bfys-physics] Fwd: Seminar Plamen Hopchev - mistake in time!
by Marcel Merk 10 Mar '11

10 Mar '11

My apologies: the seminar is at 10h30, not at 11h00 !! ---------- Forwarded message ---------- From: Marcel Merk <marcel.merk(a)nikhef.nl> Date: 10 March 2011 09:42 Subject: Seminar Plamen Hopchev To: bfys-physics(a)nikhef.nl, SiimTolk(a)gmail.com Dear friends, Today, Plamen Hopchev is visiting Nikhef for a postdoc application. He will give a 30' seminar at 11h00 in H220 (note location!) on the following topic: "The beam-gas method for absolute luminosity determination" ABSTRACT: "The high resolution of the LHCb vertex detector allows precise measurement of vertices of beam-gas and beam-beam interactions and the determination of beam parameters such as positions, angles and widths. Using the directly measured beam properties a novel method for absolute luminosity normalization has been applied for a first time at the LHCb experiment. The principle requirements and results of the beam-gas luminosity normalization procedure will be described." Hope to see you all there, - Marcel

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[Bfys-physics] Seminar Plamen Hopchev
by Marcel Merk 10 Mar '11

10 Mar '11

Dear friends, Today, Plamen Hopchev is visiting Nikhef for a postdoc application. He will give a 30' seminar at 11h00 in H220 (note location!) on the following topic: "The beam-gas method for absolute luminosity determination" ABSTRACT: "The high resolution of the LHCb vertex detector allows precise measurement of vertices of beam-gas and beam-beam interactions and the determination of beam parameters such as positions, angles and widths. Using the directly measured beam properties a novel method for absolute luminosity normalization has been applied for a first time at the LHCb experiment. The principle requirements and results of the beam-gas luminosity normalization procedure will be described." Hope to see you all there, - Marcel

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Re: [Bfys-physics] Effective Lifetime
by Marcel Merk 04 Mar '11

04 Mar '11

Bedankt Kristof, Ik stuur het gelijk door aan de groep... - Marcel 2011/3/4 Kristof De Bruyn <debkr(a)nikhef.nl>: > > Dag Marcel, > > Voor moest je interesse hebben, http://arxiv.org/abs/1011.1096 bevat een > sectie en referenties over de effective lifetime in the Bs system, inclusief > een resultaat van CDF. Vanuit de theorie is dit een erg interessante > observabele, maar meer details moet je aan Robert Fleischer vragen. > > Groeten, > Kristof > > >

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[Bfys-physics] Invited Postdoc Seminars at Nikhef
by Marcel Merk 02 Mar '11

02 Mar '11

Dear LHCb friends, Next week there will be at Nikhef five interesting 30' minute seminars on LHCb. The titles of the seminars and the rooms where they will take place are still to be announced. Tuesday 8 March at 14h30: Francesco Dettori Wednesday 9 March at 14h30: Tom Blake Thursday 10 March at 10h30: Plamen Hopchev Friday 11 March at 10h30: Manuel Schiller Friday 11 March at 14h30: Chris Thomas best regards, - Marcel

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[Bfys-physics] Comments on Bs->mumu paper
by Marcel Merk 28 Feb '11

28 Feb '11

Dear friends, Here is a proposal for the general comment I would like to submit to the Bs->mumu paper along the lines as we discussed in the meeting last friday. I have understood in the mean time that the authors are working on a condensed version of the paper, so some of our comment might already be solved. However, I do think we should inform the authors of our opinion of the first draft. --------------------------------------------------- Dear authors, This comments below result after a Nikhef group discussion of the Bs->mumu paper draft (noting that our local Bs->mumu experts were not involved). From your answers to other comments we have understood that you are currently preparing a shorter version of the paper, so we here give only our main, general, feedback. This is an excellent (and complex) analysis leading to an important result that will receive a lot of attention. However, it was generally commented in our group that the paper is very dense with information and difficult to read. Many intricacies of the analysis, although mentioned, are difficult to understand for an outsider. In several cases we had to turn to the analysis note to understand what was being done (the analysis note is of excellent quality!). We get the impression that the paper in its current state tries to include the wealth of information of the analysis note into a letter, and therefor becomes very difficult to read for an outsider. In particular it was commented in our group that the "Analysis Strategy" section in the *analysis note* was much more helpful to understand the measurement than the corresponding section in the paper. (e.g. alpha = normalization factor or *single event sensitivity*). Here are some examples that triggered our comments: Section 5.1 It is hard to understand the exact role of MC. Although we understand that the measurement uses data as much as possible for normalization, the efficiency calculations are done by MC. However, the tracking uncertainty of 4%/track is taken from another paper, where it is calibrated with data from other channels. (By the way: is the value of 4% relevant for B->mumu?). Section 5.2 This section is very dense with information and very difficult for a non-LHCb collaborator to understand. If TIS-TOS-ing is new to the reader, it is very difficult to understand the text on the bottom of page 7. Section 6 Here several details of the analysis could be skipped in a letter. E.g the exact use of Crystal Ball functions and value of alpha (confusing notation with "normalization factor" alpha). The text of the determination of the GL with B->hh , and the solution to the trigger TIS complication using emulation is difficult to follow. best regards, - Marcel for the Nikhef/VU groups

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[Bfys-physics] Fwd: B_s -> mu mu paper draft
by thomas 23 Feb '11

23 Feb '11

Dear all, as you know, the first draft of the paper "Search for the rare decays B_s > mu mu and B0 -> mu mu" is available for comments: http://cdsweb.cern.ch/record/1330372 . The deadline for comments is March 2nd. As stated previously, it would be preferable that comments from the Nikhef persons are submitted through the group, rather than as comments from individual persons. Antonio will present this paper next Friday, Feb. 25th, at 9:30 in H331, and you are kindly asked to bring up any (critical) comment during this meeting, so that all comments can be discussed and submitted on behalf of the Nikhef group. Of course it would be great if (most of) you have read (critically) the paper - or at least the majority of the paper. Kind regards Tjeerd, Thomas, Marcel, Antonio (PS: Note uncommon place: H331 ) -- Thomas S. Bauer NIKHEF email: thomas @ nikhef.nl P.O. Box 41.882 tel. : (+31)-20- 5 92 20 50 1009 DB Amsterdam, The Netherlands fax : (+31)-20- 5 92 51 55 Begin forwarded message: > From: Roger Forty <Roger.Forty(a)cern.ch> > Date: February 18, 2011 10:18:59 PM GMT+01:00 > To: "lhcb-general (LHCb General mailing list)" <lhcb-general(a)cern.ch> > Subject: B_s -> mu mu paper draft > > Dear Colleagues, > > The first draft of the paper "Search for the rare decays B_s > mu mu > and B0 -> mu mu" is available for comments:http://cdsweb.cern.ch/record/1330372 > The contact authors are Gaia Lanfranchi and Frederic Teubert, > referees are Peter Dornan, Roger Forty and Patrick Koppenburg, and > the analysis note is LHCb-ANA-2011-007. Since it is planned to > present this result at La Thuile. the review process of the paper is > somewhat accelerated: the deadline for comments is 2 March, and the > Editorial Board will meet the following day. > > Best wishes, > Roger

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[Bfys-physics] Theoretical uncertainties on fs/fd, and B0->D-pi+
by Niels Tuning 14 Dec '10

14 Dec '10

Hi friends, For your information, Robert, Nicola and me had a closer (phenomenological) look into the ratios of B->Dh decays, in the light of the determination of fs/fd. In case you are interested, we just submitted a preprint describing our findings: http://arxiv.org/abs/1012.2784 In summary, we have reached the following conclusions: 1) If we use the ratio N(B0->D-K+)/N(Bs->Ds-pi+) to determine fs/fd we argue that the uncertainty from SU(3) breaking of factorization is 2%. 2) We propose that we can also use the Cabibbo favoured decay, ie. N(B0->D-pi+)/N(Bs->Ds-pi+), for the determination of fs/fd. The price to pay is that the theoretical uncertainty is a bit larger due to the extra ("exchange") diagram in B0->D-pi+. Cheers, Robert, Nicola & Niels

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[Bfys-physics] Met trane in my oë
by Jan Amoraal 09 Nov '10

09 Nov '10

Liewe Sakworsies en ander mense, My mangum opus lê nou by die lees kommissie en dus is dit tyd om 'n lekker dop te drink in kamer N256. In English: It's time to get wasted (for me at least). cheers, Jan

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[Bfys-physics] Middagprogramma Nikhef-excursie (fwd)
by Tjeerd Ketel 09 Nov '10

09 Nov '10

For the people at Nikhef to inform them about a student excursion Tjeerd ---------- Forwarded message ---------- Date: Mon, 8 Nov 2010 19:59:39 +0100 (MET) From: Tjeerd Ketel <tjeerd(a)nikhef.nl> To: Fransje Prins <f.l.prins(a)student.vu.nl>, Jeroen Bos <jbs236(a)few.vu.nl>, Gijsbert Tijsseling <gtg300(a)few.vu.nl>, Tjeerd Ketel <tjeerd(a)nikhef.nl>, marcel.merk(a)nikhef.nl, Chris Van Den Broeck <vdbroeck(a)nikhef.nl>, Frans Mul <fmul(a)nikhef.nl>, Mark Beker <mbeker(a)nikhef.nl>, Krista de Roo <kderoo(a)nikhef.nl>, Martin Fransen <martinf(a)nikhef.nl>, Wim Heubers <wimh(a)nikhef.nl>, bfys-physics(a)nikhef.nl, gravity(a)nikhef.nl Subject: Middagprogramma Nikhef-excursie Middagprogramma Nikhef-excursie voor drie derdejaars natuurkundestudenten van de VU op dinsdagmiddag, 9 november. 13:50 Verzamelen bij de Nikhef receptie N222 of werkkamers: 14:00 - LHC, Tjeerd Ketel 14:15 - B-fysica, Marcel Merk 14:45 - Gravitatiefysica, Chris van den Broeck 15:15 - Thee Excursies: 15:30 - Clean room Virgo (Mark Beker) 16:10 - CO2 koeling (Krista de Roo) 16:10 - AmX/Grid (CT) 16:30 - Timepix (Martin Fransen) N222 of evt. andere ruimte 16:50 - Nabespreking met studenten en OIO's

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