On 03/03/14 10:38, Hella Snoek wrote:

Gerco and I am connected... We don't see Nikhef..

I am connected with Nikhef and don't see you.

Groeten, Hella

On 03 Mar 2014, at 10:25, Tjeerd Ketel tjeerd@nikhef.nl wrote:

...

Quoting Tjeerd Ketel tjeerd@nikhef.nl:

...

Dear colleagues,

Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

10:30 - 11:30 Introduction and discussion of LHCb-PAPER-2014-007 "Angular analysis of charged and neutral B to K mu+ mu- decays" by Gerco Onderwater Link http://cds.cern.ch/record/1664342

The material can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2831 and will be protected by lhcb, etc.

Vidyo link in Nikhef Bfys Meeting (at Institutes->Nikhef Bfys Meeting of Friday 21 February 2014) https://indico.cern.ch/event/303863/ protected by PIN 1328.

Best regards, Tjeerd

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Hi

Bon. Apparently "plug-in method" is something not well-defined, and there are several 'flavours' of it: http://phystat-lhc.web.cern.ch/phystat-lhc/2008-001.pdf It can be what I had in mind (i.e, just plug in an estimate, and forget about the uncertainties, which I think is wrong), but it can also be something else.

In the analysis note they write:

439 10.2.2 Nuisance parameter treatment 440 The Feldman-Cousins scan are performed using the so-called plug-in method, in which toy 441 datasets are generated with the best ?t value of nuisance parameters. Potential systematic 442 e?ects of this are tested by re-doing the scans but generating datasets with a large spread 443 of values on AFB when scanning for FH, and a large spread of values for FH when scanning 444 for AFB. These scans are compared to the nominal case where the plug-in method is 445 used in Fig. 53. The di?erence between the two, if any, is marginal and so no systematic 446 uncertainty is assigned.

which doesn't clarify to me if they do something with, eg, the uncertainties in the bkgd expectation or the acceptance.

Diego

________________________________________ From: bfys-physics-bounces@nikhef.nl [bfys-physics-bounces@nikhef.nl] on behalf of Patrick Koppenburg [Patrick.Koppenburg@cern.ch] Sent: Monday, March 03, 2014 10:39 To: Hella Snoek; Tjeerd Ketel Cc: bfys-physics@nikhef.nl Subject: Re: [Bfys-physics] Reminder: Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

On 03/03/14 10:38, Patrick Koppenburg wrote:

On 03/03/14 10:38, Hella Snoek wrote:

...

Gerco and I am connected... We don't see Nikhef..

I am connected with Nikhef and don't see you.

I am in Nikhef_Bfys_Meeting

...

Groeten, Hella

On 03 Mar 2014, at 10:25, Tjeerd Ketel tjeerd@nikhef.nl wrote:

...

Quoting Tjeerd Ketel tjeerd@nikhef.nl:

...

Dear colleagues,

Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

10:30 - 11:30 Introduction and discussion of LHCb-PAPER-2014-007 "Angular analysis of charged and neutral B to K mu+ mu- decays" by Gerco Onderwater Link http://cds.cern.ch/record/1664342

The material can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2831 and will be protected by lhcb, etc.

Vidyo link in Nikhef Bfys Meeting (at Institutes->Nikhef Bfys Meeting of Friday 21 February 2014) https://indico.cern.ch/event/303863/ protected by PIN 1328.

Best regards, Tjeerd

---

Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

---

Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

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-- ======================================================================== Patrick Koppenburg LHCb Physics Coordinator Nikhef, Amsterdam & CERN http://www.koppenburg.org/address.html

_______________________________________________ Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

Hi Jeroen

If it is done as you say, then indeed it looks ~ok (well, maybe conservative, but still ok). Note that then it implies that all their systematics are included in the likelihood fit, with the corresponding external constraints of the np's. But not clear if this is what they did. Maybe the best is indeed to ask them to confirm.

Diego

________________________________________ From: Jeroen Van Tilburg Sent: Monday, March 03, 2014 14:21 To: Diego Martinez Santos Cc: Patrick Koppenburg; Hella Snoek; Tjeerd Ketel; bfys-physics@nikhef.nl Subject: Re: [Bfys-physics] Reminder: Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

Hi Diego,

Let me iterate that my understanding of the plugin method is that it should give an over-coverage of the confidence intervals (i.e. errors will be too large). In the Feldman-Cousins method, you normally calculate the probabilities to observe some value for F_H for any true value of F_H (from the PDF of your fit model). In case of nuisance parameters, for each “observed" value of F_H, you fix F_H, fit the data and “plugin" the probability that corresponds to the best-fit value of this nuisance parameter. So this best-fit value is different for each line in this 2D grid! Therefore the confidence belt is artificially increased and this is why the plugin method may give some over coverage.

I expected it to be done like this in this particular analysis as well. The text from the ANA note that you quote below suggests that they use a different plugin method. That is why we should ask them to explain their method better (and probably refrain from calling it plugin).

Cheers Jeroen

On 3 Mar, 2014, at 13:14 pm, Diego Martinez Santos Diego.Martinez.Santos@cern.ch wrote:

Hi

Bon. Apparently "plug-in method" is something not well-defined, and there are several 'flavours' of it: http://phystat-lhc.web.cern.ch/phystat-lhc/2008-001.pdf It can be what I had in mind (i.e, just plug in an estimate, and forget about the uncertainties, which I think is wrong), but it can also be something else.

In the analysis note they write:

439 10.2.2 Nuisance parameter treatment 440 The Feldman-Cousins scan are performed using the so-called plug-in method, in which toy 441 datasets are generated with the best ?t value of nuisance parameters. Potential systematic 442 e?ects of this are tested by re-doing the scans but generating datasets with a large spread 443 of values on AFB when scanning for FH, and a large spread of values for FH when scanning 444 for AFB. These scans are compared to the nominal case where the plug-in method is 445 used in Fig. 53. The di?erence between the two, if any, is marginal and so no systematic 446 uncertainty is assigned.

which doesn't clarify to me if they do something with, eg, the uncertainties in the bkgd expectation or the acceptance.

Diego

---

From: bfys-physics-bounces@nikhef.nl [bfys-physics-bounces@nikhef.nl] on behalf of Patrick Koppenburg [Patrick.Koppenburg@cern.ch] Sent: Monday, March 03, 2014 10:39 To: Hella Snoek; Tjeerd Ketel Cc: bfys-physics@nikhef.nl Subject: Re: [Bfys-physics] Reminder: Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

On 03/03/14 10:38, Patrick Koppenburg wrote:

...

On 03/03/14 10:38, Hella Snoek wrote:

...

Gerco and I am connected... We don't see Nikhef..

I am connected with Nikhef and don't see you.

I am in Nikhef_Bfys_Meeting

...

...

Groeten, Hella

On 03 Mar 2014, at 10:25, Tjeerd Ketel tjeerd@nikhef.nl wrote:

...

Quoting Tjeerd Ketel tjeerd@nikhef.nl:

...

Dear colleagues,

Bfys Meeting Monday 3 March at 10:30 in N328 and Vidyo

10:30 - 11:30 Introduction and discussion of LHCb-PAPER-2014-007 "Angular analysis of charged and neutral B to K mu+ mu- decays" by Gerco Onderwater Link http://cds.cern.ch/record/1664342

The material can be found at http://agenda.nikhef.nl/conferenceDisplay.py?confId=2831 and will be protected by lhcb, etc.

Vidyo link in Nikhef Bfys Meeting (at Institutes->Nikhef Bfys Meeting of Friday 21 February 2014) https://indico.cern.ch/event/303863/ protected by PIN 1328.

Best regards, Tjeerd

---

Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

---

Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

---

Bfys-physics mailing list Bfys-physics@nikhef.nl https://mailman.nikhef.nl/mailman/listinfo/bfys-physics

--

Patrick Koppenburg LHCb Physics Coordinator Nikhef, Amsterdam & CERN http://www.koppenburg.org/address.html

---

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Hi Gerco,

Below my set of comments. I lost a bit of attention towards the end of the paper.

Cheers, Wouter

-------------------------------------------------

Title: - “B0->Ksmumu and B+/- \to K^\pm mu+ mu-“ is less ambiguous than “charged and neutral B->Kmumu” (since K could also refer to K* resonances).

Abstract: - “the measurements” —> “the measurements of AFB and FH reported here”

L3: don’t use slanted for "box" and "penguin" L3: “diagrams" —> “amplitudes" L5: “of the dimuon system” —> “of the final state particles”. (It is not clear what is meant with the angular distribution of the dimuon system.)

L12: Move the remark in L23-25 here. Actually, the statement is confusing: It is as if this requirement on AFB and FH is made in order to keep the equation positive, but it is the other way around: the most generic parameterisation is clearly positive, from which you find that AFB and FH apparently must obey these constraints.

L13: “and” —> “,”

L16: “As the B0-B0bar production asymmetry …” is unclear. Replace with something like: “As a result of this, a non-zero value of AFB can only be observed if there is a B0-B0bar production asymmetry or through CP violation in the decay"

(In any case “a large CP violation in AFB is confusing, of not wrong. What you mean is that CP violation in the amplitudes may lead to different values of AFB for B0 and B0bar)

L18: “However,“ —> "Ignoring CP violating effects,”

L20: “AFB of the dimuon system is zero within tiny corrections” —> “AFB is zero up to tiny corrections”.

(In any case, remove ‘of the dimuon system')

L20: “Sizable AFB values” —> “A sizeable value of AFB"

L22: remove “similarly” and replace by “as well” at the end of the sentence.

L25: Replace FH>=0 by 0<=FH<=3.

L26: “The paper” —> “This paper”

L32: “K0” -> “K0s”?

L37:”in sqrt(s) = 7 TeV pp collisions in 2011” —> “in pp collisions at 7 TeV in 2011” (otherwise inconsistent with remainder of sentence)

L81: “obvious” —> “prominent”

L85: add the number of dofs for the B vertex fit, since it isn’t necessarily clear.

L88: “lifetime" —> “decaytime” (see EB FAQs)

L 126: "to remove a small contribution fomr D0->Kp and B->D0pi decays" --> "to remove a small contribution from B->D0pi decays with D0->Kpi."

L126-127: please specify exactly how the D0 veto is implemented (mass cut)

L130: remove (this and all other appearances of) “very”

L138: “a factor ten” —> “about a factor 10”

L138: “This is [due to] a combination of three effects:” (insert "due to")

L148: why do you assume that the acceptance is symmetric around 0? (apparently, it is not, as a result of your D0 veto.)

L151: “need” —> “requirement”

L157: how do you parameterise the inefficiency caused by the D0 veto into your acceptance? (it is clearly no longer a 4th order polynomial?)

Fig 1: why do you show only the efficiency for positive cos theta_L? (the inefficiency of the D0 veto is not symmetric, is it?

L178: remove “Hence, AFB cannot be determined.”

L179-181: It is unclear what you actually fit for. Do you do a 2D fit to mass and decay angle? If so, say so. How do you form your 2D PDF? Do you assume that mass and decay angle are uncorrelated, for both signal and background? If so, say so explicitly. Did you verify that this assumption (factorisation) is actually correct? (Is the mass resolution really independent of the decay angle?) For the background, you cannot know if it is right: how did you assign a systematic?

L184: “Due to the limited …, is assumed to be uniform.” makes little sense as written. It is not clear why the sideband is relevant here. Replace with something more informative like: “Information on the angular shape of the background is obtained from events outside the invariant mass signal region. For events in the long Ks meson category, the number of events in the sideband is so small, that no information on the decay angle shape can be extracted, which is therefore assumed to be uniform. For the downstream category, it is parametrised by a second-order polynomial.”

L199: What does the statement “The fits are also repeated allowing for a non-zero AFB” mean? AFB is not present in Eq 2. Does that mean that you fit with Eq 1, using a signed cos(theta_l)? If a non-zero value for AFB would be found, wat would this mean? (What effect could generate a non-zero value of AFB?)

Fig 3b: why is the background asymmetric? why would this asymmetry not depend on the B mass?

L202: remove “In every case”

Fig 6: - Extend the y axis such that the error bars are entirely visible. - In caption: "The [vertical] error bars …” (insert vertical)

L235: why do you not add the RMS and bias of the differences in square, which is more correct (and leads to larger errors)?

L252: “For the decay B0->Ksmumu, large values of FH are observed …” They are not large: for any measurements the confidence intervals are on the positive side of zero, so you couldn't really have found anything else than this.

L254: how exactly did you define the chi2, given that your confidence intervals are asymmetric and do not actually represent an RMS? Cannot you say something about the Feldman-Cousins CL of the SM band? (“If the SM were right, 10% of experiments would have given a set of measurements that is further away from the prediction than the data is.”)

L254: Add a statement about comparison to previous experiments. (“These results are compatible with but more precise than those reported previously.”)