Comments on: No CHAMPS in CDF data http://dorigo.wordpress.com/2009/01/12/1939/ private thoughts of a physicist and chessplayer Thu, 24 Dec 2009 08:50:26 +0000 http://wordpress.com/ hourly 1 By: Philipum http://dorigo.wordpress.com/2009/01/12/1939/#comment-103725 Philipum Thu, 15 Jan 2009 11:48:16 +0000 http://dorigo.wordpress.com/?p=1939#comment-103725 Thanks ! Thanks !

]]> By: dorigo http://dorigo.wordpress.com/2009/01/12/1939/#comment-103715 dorigo Thu, 15 Jan 2009 09:41:58 +0000 http://dorigo.wordpress.com/?p=1939#comment-103715 Yes Daniel, prolly it was La Thuile after all. Philipum, yes, we are done with the paper review, and I think it will be sent to publication very soon. I will add a pointer here when it comes out (if I don't forget) Cheers, T. Yes Daniel, prolly it was La Thuile after all.

Philipum, yes, we are done with the paper review, and I think it will be sent to publication very soon. I will add a pointer here when it comes out (if I don’t forget)
Cheers,
T.

]]> By: Philipum http://dorigo.wordpress.com/2009/01/12/1939/#comment-103714 Philipum Thu, 15 Jan 2009 09:29:33 +0000 http://dorigo.wordpress.com/?p=1939#comment-103714 Hi Dorigo, Do you know when we expect these results to appear as a journal publication ? I am working on a stable stop analysis in ATLAS and often quote the limits from the Tevatron. best, Philippe Hi Dorigo,

Do you know when we expect these results to appear as a journal publication ? I am working on a stable stop analysis in ATLAS and often quote the limits from the Tevatron.

best,
Philippe

]]> By: Daniel de França MTd2 http://dorigo.wordpress.com/2009/01/12/1939/#comment-103709 Daniel de França MTd2 Thu, 15 Jan 2009 02:53:21 +0000 http://dorigo.wordpress.com/?p=1939#comment-103709 La Thuile, Aosta Valley, Italy March 1-7, 2009: http://www.pi.infn.it/lathuile/lathuile_2009.html 44th Rencontres de Moriond La Thuile (Val d'Aosta, Italy) February 1 - 8, 2009 http://moriond.in2p3.fr/J09/ It seems that Moriond is more oriented to sky surveys... La Thuile, Aosta Valley, Italy
March 1-7, 2009: http://www.pi.infn.it/lathuile/lathuile_2009.html

44th Rencontres de Moriond
La Thuile (Val d’Aosta, Italy)
February 1 – 8, 2009 http://moriond.in2p3.fr/J09/

It seems that Moriond is more oriented to sky surveys…

]]> By: dorigo http://dorigo.wordpress.com/2009/01/12/1939/#comment-103703 dorigo Wed, 14 Jan 2009 20:53:34 +0000 http://dorigo.wordpress.com/?p=1939#comment-103703 Not anything that I know of, but somebody said they're working at it, and I also know that D0 might (just might) have a slot to talk about their own results on this matter at La Thuile (or was it Moriond ?). Cheers, T. Not anything that I know of, but somebody said they’re working at it, and I also know that D0 might (just might) have a slot to talk about their own results on this matter at La Thuile (or was it Moriond ?).

Cheers,
T.

]]> By: Daniel de França MTd2 http://dorigo.wordpress.com/2009/01/12/1939/#comment-103697 Daniel de França MTd2 Wed, 14 Jan 2009 14:58:39 +0000 http://dorigo.wordpress.com/?p=1939#comment-103697 Hi Tommaso, any gossip about the anomalous multi muon on D0? Cheers, Daniel Hi Tommaso,

any gossip about the anomalous multi muon on D0?

Cheers,
Daniel

]]> By: dorigo http://dorigo.wordpress.com/2009/01/12/1939/#comment-103673 dorigo Tue, 13 Jan 2009 10:28:29 +0000 http://dorigo.wordpress.com/?p=1939#comment-103673 Hi Andrea, well, the dE/dx by ionization of a stau or a stop R-hadron does depend only on the charge, velocity, and the mass of the particle, so in principle there is model independence even if one uses that. For a fractionary charge things would be different... But I doubt anybody is interested in such a scenario. I believe that the reason dE/dx was not used is really due to the fact that the combination of timing measurements has smaller backgrounds -the one in the paper is indeed a novel technique for CDF. As for "TOF subgroup" and "dE/dx subgroup", CDF does not work that way. There is shortage of manpower these days, and I doubt there will be another search for CHAMPS in the same data. Maybe a future one with 3,4, 5 /fb will revert to using the dE/dx, but I doubt that too -much more likely that the same authors will repeat the present analysis with the larger dataset. Cheers, T. Hi Andrea,

well, the dE/dx by ionization of a stau or a stop R-hadron does depend only on the charge, velocity, and the mass of the particle, so in principle there is model independence even if one uses that. For a fractionary charge things would be different… But I doubt anybody is interested in such a scenario.

I believe that the reason dE/dx was not used is really due to the fact that the combination of timing measurements has smaller backgrounds -the one in the paper is indeed a novel technique for CDF. As for “TOF subgroup” and “dE/dx subgroup”, CDF does not work that way. There is shortage of manpower these days, and I doubt there will be another search for CHAMPS in the same data. Maybe a future one with 3,4, 5 /fb will revert to using the dE/dx, but I doubt that too -much more likely that the same authors will repeat the present analysis with the larger dataset.

Cheers,
T.

]]> By: Andrea Giammanco http://dorigo.wordpress.com/2009/01/12/1939/#comment-103672 Andrea Giammanco Tue, 13 Jan 2009 09:51:15 +0000 http://dorigo.wordpress.com/?p=1939#comment-103672 Thanks a lot for the clarification. I should probably explain why I am interested in that: I'm involved in the set-up of such a search in CMS, specifically working on the dE/dx side, and as far as I know the dE/dx by ionization has no significant model dependence (while, of course, the energy deposit in the calorimeters is totally model dependent - indeed it would provide a wonderful way to discriminate between lepton-like and hadron-like CHAMPs in case of discovery). My guess: maybe the TOF subgroup in CDF finished its analysis before the dE/dx subgroup, and when both will have completely validated their respective methods they will come up with a combined note? (A bidimensional plot of TOF versus dE/dx would be the ultimate smoking gun for a discovery - or for killing a claim of discovery coming from only one of the two methods - since the betas inferred from the two variables are uncorrelated or even have opposite behaviours for the main backgrounds.) Thanks a lot for the clarification.
I should probably explain why I am interested in that: I’m involved in the set-up of such a search in CMS, specifically working on the dE/dx side, and as far as I know the dE/dx by ionization has no significant model dependence (while, of course, the energy deposit in the calorimeters is totally model dependent – indeed it would provide a wonderful way to discriminate between lepton-like and hadron-like CHAMPs in case of discovery).
My guess: maybe the TOF subgroup in CDF finished its analysis before the dE/dx subgroup, and when both will have completely validated their respective methods they will come up with a combined note? (A bidimensional plot of TOF versus dE/dx would be the ultimate smoking gun for a discovery – or for killing a claim of discovery coming from only one of the two methods – since the betas inferred from the two variables are uncorrelated or even have opposite behaviours for the main backgrounds.)

]]> By: dorigo http://dorigo.wordpress.com/2009/01/12/1939/#comment-103662 dorigo Mon, 12 Jan 2009 23:02:47 +0000 http://dorigo.wordpress.com/?p=1939#comment-103662 Hi Ervin, I have no idea on the implications for the multi-muon interpretations... As you know, there are a few, but they are not very clear nor do they make very specific predictions. The authors have their own model, which implies the cascade of several bodies which are long-lived in the sense that they have a lifetime of about 20 picoseconds. These particles are however neutral. It seems to me that these limits can well coexist with a neutral higgs boson which produces some cascade to hidden valley particles. Andrea, yes, the CDF COT does measure dE/dx rather well and it discriminates protons from deuterons, for instance. With the latter, the method of determining residuals from the track fit has been tuned and verified. That is, they select deuterons with the dE/dx, and then, by knowing the mass of the particle, they can verify that the residuals are consistent with the velocity they infer from the momentum measurement for deuterons. The search does not make use of dE/dx other than that (contrarily to what was done in Run I, see Phys. Rev. Lett. 90, 131801 (2003)), although I think it could well do it. I am not sure whether avoiding dE/dx info one retains more model-independence. Cheers, T. Hi Ervin,

I have no idea on the implications for the multi-muon interpretations… As you know, there are a few, but they are not very clear nor do they make very specific predictions. The authors have their own model, which implies the cascade of several bodies which are long-lived in the sense that they have a lifetime of about 20 picoseconds. These particles are however neutral.
It seems to me that these limits can well coexist with a neutral higgs boson which produces some cascade to hidden valley particles.

Andrea, yes, the CDF COT does measure dE/dx rather well and it discriminates protons from deuterons, for instance. With the latter, the method of determining residuals from the track fit has been tuned and verified. That is, they select deuterons with the dE/dx, and then, by knowing the mass of the particle, they can verify that the residuals are consistent with the velocity they infer from the momentum measurement for deuterons.

The search does not make use of dE/dx other than that (contrarily to what was done in Run I, see Phys. Rev. Lett. 90, 131801 (2003)), although I think it could well do it. I am not sure whether avoiding dE/dx info one retains more model-independence.

Cheers,
T.

]]> By: Andrea Giammanco http://dorigo.wordpress.com/2009/01/12/1939/#comment-103660 Andrea Giammanco Mon, 12 Jan 2009 22:42:55 +0000 http://dorigo.wordpress.com/?p=1939#comment-103660 > It is interesting to note that this analysis, while not using the magnitude of the ionization left by the track in the gas chamber (the so-called dE/dx on which most past searches of CHAMPS have been based, e.g. in CDF (Run I) and ALEPH), does use the dE/dx to infer the particle species when determining the resolution of the time measurement from COT residuals. Do you mean that the dE/dx in the CDF tracking system is able to discriminate SM particles between them in some kinematical regime, but this ability is of no use in the search for CHAMPs? Probably I misunderstood, can you clarify better how dE/dx is used in this analysis? (I've already had a quick look at the webpage and at the note linked there.) > It is interesting to note that this analysis, while not using the magnitude of the ionization left by the track in the gas chamber (the so-called dE/dx on which most past searches of CHAMPS have been based, e.g. in CDF (Run I) and ALEPH), does use the dE/dx to infer the particle species when determining the resolution of the time measurement from COT residuals.

Do you mean that the dE/dx in the CDF tracking system is able to discriminate SM particles between them in some kinematical regime, but this ability is of no use in the search for CHAMPs?
Probably I misunderstood, can you clarify better how dE/dx is used in this analysis?
(I’ve already had a quick look at the webpage and at the note linked there.)

]]> By: ervin http://dorigo.wordpress.com/2009/01/12/1939/#comment-103657 ervin Mon, 12 Jan 2009 20:40:06 +0000 http://dorigo.wordpress.com/?p=1939#comment-103657 Tommaso, Can you please elaborate on the implications (if any) of this finding for current theories regarding the CDF anomaly? Specifically, how does the search for CHAMPS affect models that explain multi-muon events starting from various Dark Matter candidates? Thank you. Ervin Tommaso,

Can you please elaborate on the implications (if any) of this finding for current theories regarding the CDF anomaly? Specifically, how does the search for CHAMPS affect models that explain multi-muon events starting from various Dark Matter candidates?

Thank you.

Ervin

]]> By: dorigo http://dorigo.wordpress.com/2009/01/12/1939/#comment-103656 dorigo Mon, 12 Jan 2009 20:06:01 +0000 http://dorigo.wordpress.com/?p=1939#comment-103656 Yep ominous. No explicit limits on staus, but my guess is it does not improve the 99.5 GeV of LEP combined. The 10 fb is a limit for weak CHAMPs with some acceptance cuts applied, so the limit is a bit weaker than that overall. Cheers, T. Yep ominous. No explicit limits on staus, but my guess is it does not improve the 99.5 GeV of LEP combined. The 10 fb is a limit for weak CHAMPs with some acceptance cuts applied, so the limit is a bit weaker than that overall.

Cheers,
T.

]]> By: onymous http://dorigo.wordpress.com/2009/01/12/1939/#comment-103654 onymous Mon, 12 Jan 2009 18:40:00 +0000 http://dorigo.wordpress.com/?p=1939#comment-103654 (Rough estimate: 10 fb xsec for staus translates to a limit of around 100 GeV on the mass, which is a bit better than LEP did.) (Rough estimate: 10 fb xsec for staus translates to a limit of around 100 GeV on the mass, which is a bit better than LEP did.)

]]> By: onymous http://dorigo.wordpress.com/2009/01/12/1939/#comment-103653 onymous Mon, 12 Jan 2009 18:08:46 +0000 http://dorigo.wordpress.com/?p=1939#comment-103653 Any idea why a limit for stop is quoted but not for stau? Staus are likely CHAMPs in a wide variety of models.... Any idea why a limit for stop is quoted but not for stau? Staus are likely CHAMPs in a wide variety of models….

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