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Nima Arkani-Hamed’s letter on multi-muons – and my reply November 3, 2008

Posted by dorigo in news, personal, physics, science.
Tags: , ,

I had the pleasure of seeing Nima Arkani-Hamed -an IAS/Harvard University theoretician- visit this blog this morning. Nima, together with some colleagues, published three weeks ago a couple of papers where they discussed the possibility that hadron colliders put in evidence a signature of new physics in the form of lepton jets, produced by particles with long lifetime – a signature strikingly similar to the one CDF published a few days ago.

In the thread developed at Peter Woit’s site Neal Weiner, a colleague of Nima and a co-author of his papers, claimed:

“I can tell you officially we had no word on this. This blog is, in fact, the first I’d heard of it.”

and I replied, in my usual talk-first-think-later style:

“that is pretty hard to digest. Lepton jets with lifetimes. Come on. I think you owe it to the physics community to let us know where the leak came from.”

I later regretted, as I often do, to have been so explicit in saying what I think. But the fact remains that many among my colleagues think the same thing, so the physics community does need some sort of explanation. Nima’s comment, which I paste below, somehow fills that gap, although he also complains with me for what I wrote, implying I said Neal is a liar. I did not call Neal a liar: their paper has many authors, and even just one of them might have heard news about a multi-lepton signal in CDF to come out soon, and this might have been the source of the coincidence. Anyway, here is what Arkani-Hamed wrote:


As most of my friends and colleagues know, I have a very dim view of
the physics blogosphere, and avoid interacting with it. However, your
statements about me and my collaborators in connection with the recent CDF anomaly quite clearly crossed a line, and I feel compelled to respond. In doing so I am adopting an attitude Howard Georgi once described when dealing with non-perturbative QCD effects in heavy quark effective theory: once I am finished dealing with the brown muck, I will wash my hands.

It was stimulating to see the CDF paper. However, this is an extremely challenging analysis, and many further cross-checks will have to be done to take it as a serious indication for physics beyond the standard model. We are all well aware that particle physics anomalies have come and gone in the past two decades, in analyses that are less complicated than this one; of course the collaboration made no claim to have discovered new physics. Keeping this in mind, let me first make comments on some physics I have been involved with, and end with some comments on sociology.

I have been working recently with Doug Finkbeiner,Tracy Slatyer and Neal Weiner on a theory for dark matter motivated by a growing number of anomalies in astrophysics, most recently PAMELA/ATIC.
This work is a direct continuation of (in my view) beautiful earlier work pioneered by Neal, Doug and Dave Tucker-Smith, who have collectively pushed it for many years. In fact, Neal, Doug and others previously talked about GeV scalars decaying to leptons in the context of “exciting” dark matter, to explain the INTEGRAL signal, as well as the HEAT excess predecessor to PAMELA. So the idea of GeVish mass particles decaying to leptons, motivated by Dark Matter anomalies, goes back to Feb 2007–Feb 2008. See e.g. astro-ph/0702587 and especially arXiv:0802.2922.

What we did in our four author paper was to show that all these strands fit together into a simple unified picture that also makes very good particle physics sense. The idea can be summarized in one sentence: Dark Matter is charged under a non-Abelian gauge symmetry broken at the GeV scale. We pointed out two additional major motivations for the GeV scale–first, the new vectors with this mass naturally “Sommerfeld enhance” the annihilation cross section as appears necessary to explain the PAMELA/ATIC signals from DM
annihilation; second, the broken gauge symmetry at the GeV scale radiatively induces splittings between the different states in the DM multiplet at the \sim MeV scale, which is precisely what is needed in “exciting” and “inelastic” DM explanations of the INTEGRAL and DAMA signals. All of these phenomena, scattered over energy scales ranging from a TeV to an MeV, are essentially a consequence of the single sentence I used to describe our picture above. We find this compelling.

Since the GeV gauge sector is non-Abelian, there are a number of
states, minimally including vectors and higgses, all GeVish in mass.
One thing that happens when at least some of these GeV particles are vectors is that they can easily talk to the Standard Model, via kinetic mixing with the photon. The mixing is naturally small, so directly producing this particle is challenging–though people have
talked about doing it at low-energy e+ e- machines (B-factories,
DAPHNE, BESS). Neal and I considered the simplest marriage of our DM picture with low-energy SUSY, which further naturally generates the GeV dark gauge symmetry breaking scale. We also
pointed out that in this set-up, one could produce particles in this new GeV sector much more copiously, not directly, but indirectly through SUSY production: every SUSY event will end with MSSM LSP’s which then decay into the true LSP in the dark sector; essentially all of these will also be accompanied by some of the GeVish particles that re-decay back into SM leptons. One would expect a cascade of decays in the GeV sector given the multiplicity of states, and thus the aptly named “lepton jets”. We discussed displaced vertices as a possibility, though they are not guaranteed. So, seeing “lepton jets” as an O(1) fraction of SUSY signals is what we talked about as the smoking gun of our model at the LHC. It would indeed be an amazing signal, which is why we were and continue to be very excited about it!

Now, even if the CDF anomalies are an indication of new physics–which I think in all of our views is _very_ far from obvious– it can not be due to the signal Neal and I talked about, arising from SUSY cascade decays. The rate of the CDF anomaly is absolutely
enormous–you are talking about 70,000 “ghost” events! If there is a connection to our model at all, it would likely have to be through direct production of the GeV sector particles, that still cascade decay in the dark sector and produce the lepton jets. As I mentioned there are limits one can put on this from e+ e- data, and a number of us had been wondering what could be done at hadron colliders, but at least my instinct was that the rates wouldn’t be high enough and it would be far too messy and difficult to extract a signal. We were planning on thinking about this in more detail soon, but the exploration of the consequences of our model is very new, and for now most of us have been focusing on getting out the important predictions on the DM side for GLAST/Fermi, as well as fleshing out the big O(1) LHC predictions. Obviously, stimulated by the CDF result, studying the question of direct production at the Tevatron is much higher on our list of priorities, and we are looking at it now to see if it can even be in the right ballpark. But to re-iterate: even if the CDF anomaly is new physics, and even if it is connected to our model, (and needless to say these are two very big “ifs”), it would be a wonderful surprise to me since I had expected probing direct production of the GeV sector to be incredibly difficult at a hadron collider.

So much for the physics. Turning to the sociology: you publicly suggested that we had gotten wind of the CDF experimental result ahead of time, and casually wrote this paper pointing out the signal before the experimental result was published. Your only evidence is that we made a surprising prediction of a signal experimentalists hadn’t thought of before and put it out before the experimental
results were made public–Gasp! Shocking! Scandalous! Never happened in the history of physics! Not contained in the definition of the word “pre”diction! This was a hilariously preposterous accusation;
however it stopped being funny when you went further and all but
called Neal a liar when he stated unequivocally that we had no advance knowledge of the CDF result–this is outrageous. As Neal said, we had no knowledge about the experimental result ahead of time _at all_. We didn’t even talk about the Tevatron in our paper! And as I said above, even if this anomaly is real and even if it is related to our model, it can not be literally the signal we talked about. Also, the thought that we could somehow cook up a model motivated by explaining dark matter anomalies as a cover to explain rumored events at CDF is absurd–ask any theorist friends you may have whether this is feasible and you will get a good chuckle out of them. You think this signal “came out of the blue”, but if you have been following any of the developments in BSM collider physics in the past couple of years you will realize that signals involving high particle multiplicities with displaced vertices have been discussed for quite a while–check out the repeated use of the phrase “hidden valley” in my paper with Neal for references to work by Strassler, Zurek et. al. Our contribution is that a rather specific version of such a picture–with the GeV mass scale and coupling to the SM through kinetic mixing with the photon–is naturally singled out by the new picture of dark matter we put forward with Doug and Tracy, giving a potentially exciting connection between what we are now seeing in the sky and what we might see at colliders. As it happens this type of hidden valley model had not been discussed in the literature, so we happily pointed out some of their possibly dramatic LHC consequences. Perhaps if you had bothered to even superficially read our papers and think about the physics, it wouldn’t seem so “out of the blue” to you, and you would understand that these light GeV particles decaying to leptons are a necessary feature of our model of Dark Matter, whether CDF saw any hints for them or not.

I find your cynicism remarkable. We are entering what promises to be a golden era of amazing experiments in high-energy physics, astrophysics and cosmology, which may very well lead to profound advances in our understanding of Nature at a fundamental level. All of us–experimentalists and theorists alike–are fantastically excited about this and are doing everything we can to give it the best chance of happening. And at least most of us don’t think of physics as a soap opera rife with rumor and innuendo, or spend the precious time we have cynically tossing around completely baseless and deeply offensive accusations.

Speaking of precious time, I’m sure you’ll agree that there is more critical physics to do than there are hours in the day to do it,
and I for one would like to get back to work.

Nima Arkani-Hamed

And here is my reply:

Dear Nima,

thank you for taking the time to explain more in detail what was the creative process behind the two papers you recently published. If you read my comment on Peter’s blog, you know I did ask for something like what you wrote above: an explanation of how you came to consider the striking signature we are discussing about.

If I insulted you or your colleagues with my remark, then please accept my apology, and forward these to them. I am a sceptic not only with respect to SUSY (which may be excused, since I am in good company), but also with respect of the CDF result itself. And I found it really a remarkable coincidence, to avoid putting new words out which may be found aggressive, that no more than three weeks before the CDF result is aired, you come up with lepton jets, with long lifetime, and with small invariant mass. Of course, that is not a copyrighted signature, so I am the one at fault – I am speculating. But indeed, I was not the only one who found this coincidence fishy. Many of my colleagues in CDF did, and so did others outside.

So, to summarize: I am pleased that you chose to come down to this blog to explain what caused you to discuss that signature. I will need time to digest what you wrote, because I am basically an ignorant. In earnest, I have to say I am still sceptical that there were no influences in your creative process. But I guess that is ok. The material is there for anybody to read and make their own opinion, and your text above will help creating those opinions.

Keep up with the good work,

So, I should like to open a poll for those heroic readers who came to the bottom of this post: did you read Nima’s papers ? Do you think there was a leak or do you rather think it was their own cooking ? I would be happy to hear I am the only one who still believes there was some internal information which was passed to the group who wrote those papers…



1. Not Even Wrong » Blog Archive » The Circus Begins - November 3, 2008

[…] Over at Tommaso Dorigo’s blog there’s a short posting about Giromini et. al., and an exchange with Nima Arkani-Hamed, who claims to have had no inside knowledge of the CDF “lepton jets” when he wrote his […]

2. Matti Pitkänen - November 3, 2008

I have seen so much inhonesty during these years that I find it very difficult to imagine that there was no information leakage taking into account the position of Nima in hegemony.

Matti Pitkänen

3. Daniel de França MTd2 - November 3, 2008

So basicaly Nima says his model cannot correspond to the what the number of “ghost” examples. But it doesnt look like what he says in his article http://arxiv.org/PS_cache/arxiv/pdf/0810/0810.0714v2.pdf p.14

“Clearly there are many more combinatorial possibilities one could envision; we have engaged in this brief discussion here only to make it clear that regardless of the identity of LSPSM, SUSY events will lead to decays into the Dark sector, and these will in return decay back into leptons in our sector, which we now turn to. [lepton jets]”

So, he can modify the Dark sector at will until he finds something, or anything that makes any number of events he wants.

Anyway, in that same page:

“Regardless of the displaced vertices, the lepton pairs will have
a small invariant mass ,~ aGEVVnd in typical decays, will come out with small angular separation  1/γ ~ 10^−2.”

The separation in the experiment is 36º, that is, around 10^-1. But, according to their formula, γ ~ MLSPSM/mDark, so that you would have a mess to try to fit any dark particle into this scheme.

4. Aaron Bergman - November 3, 2008

Nima is at the IAS now.

5. Daniel de França MTd2 - November 3, 2008

By mess, I eman, they would have to show that at least 3 Dm exists. One for pamela, one with small cone separation and other with a large cone separation.

6. Doug Finkbeiner - November 3, 2008

Dear Tommaso,

First a thank you – this controversy has caused a surge of interest in our papers — and I am sure in your blog. Unfortunately, I believe the controversy is purely manufactured, like so many we in the US have been forced to endure in the final days of a presidential campaign.

There is nothing here.

Nima has written a more detailed and enlightening response than I have the ability or inclination to. But since the “other two co-authors” have been called out as possible sources of the imagined “leak” I would like to respond on behalf of my grad student, Tracy Slatyer, and myself.

You have my word that none of the four authors had any idea what was coming from CDF. Now, since we have never even met, I suppose my assurances may not be meaningful to you. Perhaps more convincing would be the fact that none of us have claimed to have predicted the signal in question. The CDF signal is simply enormous compared to the signal expected from indirect production in the Arkani-Hamed and Weiner paper (0810.0714). So nobody has *at any time* claimed to have predicted what CDF saw. Hence my statement that the controversy is purely manufactured.

The thing we will claim (and forcefully) is that Neal and I have been talking about a new light state that decays to muons or electrons as an explanation for the INTEGRAL signal (see astro-ph/0702587) since October 2006. I have the battle scars to prove it. But I doubt you are going to claim the CDF result was leaked that long ago. Everything we have done since then follows in a pretty straight line (though Nima’s contributions since then have been essential and far from trivial), and so is not “out of the blue.”

To claim otherwise is absurd. It is actually very difficult to express *how* absurd it is to me (as an astrophysicist) to find someone unable to accept that an important particle physics concept might arise from astrophysical data, with no input from colliders. Perhaps it will help you to see our perspective if I repost your original criticism, slightly edited.
(see the original at
comment 12, or just search for Yeti)
I do this with a light-hearted intention, since I have no desire to make an enemy of a good chess player. Hopefully we can all have a good laugh:

==================== (begin satire)

As for CDF and their claims: we are adults and we know astrophysics. We have read hundreds of papers and published dozens. We know that people chats in the corridors. And I personally know in this particular case that the PAMELA team was not as careful with their data as they should have been prior to publication.

On the other hand, there is this paper from CDF coming out of the blue, which casually gets published a few weeks after our group posts its model to explain PAMELA, and several months after the PAMELA team itself has measured the positron excess and has its papers in internal review. This phenomenal CDF paper discusses a signature almost never heard of before. It entails a new light particle decaying to leptons — an idea that I know for a fact has been findable with google since 21 Feb 2007 (and is still at http://arxiv.org/abs/astro-ph/0702587).
In fact, the first hints of this idea go back to Neal Weiner and Dave Smith in 2001 (http://arxiv.org/abs/hep-ph/0101138).

I say, you can believe in the Yeti, or the WMAP haze, or whatever you want. I can believe a lot of things, but I do not buy that CDF actually thought up the idea of lepton jets. Especially since their paper is rather handwaving in tone and conclusions.

So, to summarize, it may sound offensive to be inquisitive with
respectable experimentalists about where the hell they got their muon jets. But it is no less offensive to act nonchalant and pretend we buy this incredible coincidence without a detailed explanation — especially when we know how much good a manufactured controversy can do for an experiment in the last days of the Tevatron.

==================== (end satire)

In conclusion, we are not particularly amused at having our collective integrity questioned by strangers, and hope that those concerns have now been addressed. We will not be baited into further discussions on that topic.

As for the physics, there may be a non-negligible chance that we (and CDF) are on the right track with new light particles going to lepton jets. We are anxious to try to figure out whether our model has any connection with the CDF claim (if we can be halfway convinced it is real).

This is high octane speculative science at its finest, and I look
forward to many constructive exchanges with members of CDF.

Best regards,
Doug Finkbeiner

7. W Barletta - November 3, 2008

Though I have not read the papers described in his letter, I see no reason not to take Nima at his word. If someone has clear evidence to the contrary, put it on the table. Otherwise, asking for a poll is both meaningless and offensive.

8. dorigo - November 3, 2008

3 Daniel, the MAXIMUM separation is 37.8 degrees, but the invariant mass of pairs of leptons in CDF signal is 1-2 GeV. Thus, perfectly matching Nima’s predictions.

Let us all be careful here: There has been a paper, actually two, from Run I of CDF. There, dileptons with small invariant mass have been observed. In fact, that is the motivation of the analysis we are discussing here.

So, if Nima says “I saw the Run I CDF papers and got inspired”, I am more than happy to give him extra points for credibility. If he says “I know nothing about CDF, and mine was an extrapolation from Pamela (or other theory-motivated speculation)”, then I am suspicious.

Regrettably, he chose the second path.

#5 Thanks Aaron, corrected.

#6 W.B., read the papers if you want your opinion to count more than zero. However, I am not asking for a poll. I am just trying to gauge whether I am the only one who thinks this coincidence is too much to buy.

Cheers all,

9. Daniel de França MTd2 - November 3, 2008

#7 Tommaso, “Daniel, the MAXIMUM separation is 37.8 degrees, but the invariant mass of pairs of leptons in CDF signal is 1-2 GeV. Thus, perfectly matching Nima’s predictions.”

Hmm, I thought that the angular separation would depend on the γ, so, I thought of the maximum angular separation as a upper bound. On the mass. But even taking the small angle, the lower bound, it would give 10-20 GEV, which is also bad.

10. dorigo - November 3, 2008

Hi Daniel,

well, the muons are central in CDF (\eta<1), so rapidity is not in the equation too much. The excess peaks at 1 or 2 GeV. Where do you get 10-20 GeV ? These muons have typical momenta of 3-5 GeV. The invariant mass of small-angle combinations is in that ballpark.


11. dorigo - November 3, 2008

Hi Doug,

thank you for your comment, and for the irony – which I really appreciated.

I think you realize that some of your colleagues may have known about the CDF signal and left you in the dark. But I understand it if you prefer to think otherwise. I am not convinced by Nima’s reply, but I am not interested in investigating further. I only care about whether the signal is real or not, after all. If Nima gets a Nobel prize and IF he has given some lead before publishing his papers – well, who cares….

So, my bottom line is: I do not want anybody to get pissed at me if I remain sceptical. Rather I encourage you, and others, to think about the CDF excess and find SM and BSM interpretations of it. I appreciate your pacate answer, which does not bring in the equation brown muck as your fellow Nima.


12. goffredo - November 3, 2008

I haven’t had so much fun in years. Great thread

13. Kea - November 3, 2008

I never fail to be amazed at how, in this day and age, people don’t realise that their emails will be published on the blogosphere. I thought he was very rude. Anyway, who cares about their Dark Matter theory. Clearly it’s wrong.

14. Daniel de França MTd2 - November 3, 2008

Hi Tommaso,

see the fig. 3 and fig. 4, the lightest supersymetrical etc. (M_LSPSM) is always above M_LSPdark, which is of order of 100 GEV to 1TEV


everything is right

15. dorigo - November 3, 2008

Kea, that was not his email, but a public comment… In any case, I can take a lot of beating with a smile.


16. dorigo - November 3, 2008

Thanks Jeff, happy you liked reading the aftermath of Giromini’s paper.


17. John A - November 3, 2008

I don’t understand *why* anyone, if they had inside information, would write down a model which clearly can not explain the “ghosts” without bending over backwards and praying for a miracle to get the rate high enough. I mean if you think this is some machiavellian conspiracy fine thats a possibility. However is seems more likely that this seems like this is just you commenting from a purely sociological standpoint because you dont understand theory. What matters is not just what is characteristic in the detector for the signal, but also HOW OFTEN, and their theory just doesnt work for that. Unfortunately when the first result is commented on without the commenters knowing what they are talking about wrt how the theory works (you and peter) this makes it a quite difficult situation. I genuinely don’t think you meant any offense, but come on when there are all these silly accusations being thrown around before the physics is even bothered to be understood it’s RIDICULOUS!!!!

18. News from the CDF and PAMELA experiments « Theorema Egregium - November 3, 2008

[…] Update: Well-known physicist Nima Arkani-Hamed clarifies the genesis of and motivation for his recent papers (published a few weeks before the CDF result) # ## over at Dorigo’s blog. His response denies previous suggestions that he and his collaborators had access to CDF results before their publication. Dorigo writes a new post on this here. […]

19. dorigo - November 3, 2008

Dear John,

good lord, you want to explain to me what a cross section is ? Be my guest, but please, get down that pedestal, I do not even know who you are…

All I am saying is that there are many people, including me, who think it is quite extraordinary that the signature of lepton jets, with long lifetime, with low dilepton invariant mass, is mentioned three weeks before a potentially groundbreaking result is published. And since extraordinary events require extraordinary explanations to be believed, I think we need more than the outrage of a few distinguished theorists to wipe that cloud off our minds.

The cross section is wrong ? Sure, the cross section of what ? Did you stop and compute exactly what could be the source of these events, its numerical size, its origin… Everything is clear to you, isn’t it ? Of course the cross section is hard to reconcile with anything. It is large, simply. Should a theorist stop trying to model the features of the signal ? Do we know what is the interaction which produced these ghost events ? You need to try harder.

You say that accusations fly around before we bother to understand the physics, but you do not give me an argument that makes me feel you do. You look like a troll to me, sorry.


20. Chris Oakley - November 3, 2008


Given that NOBODY yet has a good explanation – who cares?

A lot of fuss about nothing.

21. Anonymous - November 3, 2008

Whether there was a leak or not is obviously not something that is decided by a poll. Pray tell then, what is the purpose if this post? I thought your comment response to Nima was very good. But, IMO, this particular post is, IMO, the “brown muck” that Nima had been disparaging. Let it be.

22. 74. Nima and CDF anomaly - November 3, 2008

[…] Nima explains on the Tommaso Dirrigo’s blog that he did not know anything about CDF results while his paper was in […]

23. Ptrslv72 - November 4, 2008

Hi T.,
it seems to me that, as a good chess player, you should recognize when it’s time to concede and gear up for the next game. You throw around allegations that you cannot prove, question other people’s integrity, and when they reply – understandably annoyed – and explain to you why your accusation is unfounded, all you can come up with is “OK, but you haven’t convinced me”. Sorry but I find it a bit lame. If someone argues with his cat he might not convince him either, but this does not mean that the argumentation is not good…

24. tripitaka - November 4, 2008

Well I do get pretty pissed off hearing researches say they “have a very dim view of the physics blogoshere”.

If they are fully financing their own research well fine but in most cases the humble taxpaying public (yes we read the blogs, where else are we going to go for information?) deserve a least a token nod of appreciation.

25. Iphigenia - November 4, 2008

TD — I think you should offer a 100% apology to Weiner and Finkbeiner and his student. They are the real victims here, surely.

26. Iphigenia - November 4, 2008

By the way, TD should be thanked for bringing out into the open what a lot of people are thinking. NAH is now trying to claim that his model doesn’t predict these observations. I predict that this message will “evolve”: if these observations are confirmed, this claim will gradually fade away. It’s called having your cake and eating it too.

27. Haelfix - November 4, 2008

Nima et als explanation seems perfectly reaonable to me. The off center tracks have been a part of hidden valley phenomenology for awhile (see Strassler), usually arising in different BSM contexts. The lepto favored signal in the context of DM goes back to something like 2001.

The only thing new of relevance to this discussion is the paper in question picks out an energy scale that happens to coincide with the CDF anomaly. In short, it could be nothing more than a numerical coincidence. Surely, as physicists we are used to that happening, both in practise and in papers.

If there’s more to it than that (and I remain skeptical), good, let them get a Nobel prize, but I don’t see the need for a miscreant hypothesis in explaining whats occured. The paper in question is a nice phenomenology paper that stands on its own merits, regardless of whether its ultimately true or not.

28. Frank - November 4, 2008

I take no side, but I find the end paragraph in Nima’s missive quite immature: I am too busy to participate of your antics (yet I do). Yes Nima, you are busy, as much as a theoretician can be. Let’s hope this is true inspiration and not yet another case of the shameless parasitic behavior that your kin has sadly exhibited so often in the past. I want to believe.

29. Arun - November 4, 2008

It comes from the McCain school of physics….

30. dorigo - November 4, 2008

Peter #23,

I do not think I questioned anybody’s integrity when I asked for an explanation. These are several authors. One says he did not know about the paper, venturing to say he has “an official answer” half an hour after the CDF paper appears.

That is pretty spectacular to me, but anyway I just say “you (the authors) better tell us where the leak came from”. I am saying I hope somebody explains: maybe just one author got some “wind” of the result in preparation. Nima comes forth and says I am brown muck. I do not get offended, and reply with an apology. What exactly you question of my behavior ?


31. Luboš Motl - November 4, 2008

Dear Tommaso,

throughout this exchange, you are showing that you are extremely strong at conspiracy theories invented for the entertainment of the stupid and evil people but rather weak in the actual science.

Nima has explained you that the link between the (huge number) of CDF events and the “lepton jets” as predicted by the supersymmetrized PAMELA-friendly model of the hidden sector is surely not as straightforward as your superficial linguistic analysis suggests.

People like you or crackpot W*it have immediately determined that if there is the term “lepton jets” kind of appearing at two places, the issue is settled and the only thing that remains is to trash talk the real physicists – which is what they’re doing 99% of the time, anyway. You don’t seem to be interested in the identity of the particles inside the cascades or the expected number of events that should be seen according to one model or another, or the observations.

There is nothing unusual about Nima and Neal inventing a supersymmetrization of a model that needs supersymmetry for naturalness, and there is nothing surprising about their ability to analyze the physics and experimental signatures of such a model. I understand that this fact – and the ability of good scientists to actually make predictions out of theories – may sound surprising to someone who is not that good at physics but it’s true, anyway.

Also, there is nothing spectacular about Neal writing a reply a short time after a posting about the topic is published on the crackpot discussion forum at Columbia University. Why? Because a large enough number of people in particle physics follow the crackpot blog. Many of them who do so frequently know Neal or Nima so they could alert them very quickly. And Neal could read the crackpot blog himself.

At any rate, it is very unfortunate to invent these dumb accusations exactly at the time when a new exciting physics may be imminent. And it is even crazier to invent the accusations against some of the heroes of this potentially exciting development. You shouldn’t just apologize. You should pour 20 liters of your sh*t back on your head and shoulders, take a picture, and show the world what you really are.

Mediocre wishes, Tommaso, to you and the jealous limited simpletons who enjoy your low-brow attacks 😉


32. chris - November 4, 2008

until now i didn’t realize where the brown muck reference came from. really interesting to know and very telling.

33. Ptrslv72 - November 4, 2008

Hi T.,
the article on collider signatures has TWO authors, they both came out to tell you that they did not know about the CDF results, and your reply amounted to “I am sorry if I offended you but I still think that one of you is lying (and we all guess who)”. Not much of an apology… Mind, it might even be that you are right, but unless you can prove the allegation you end up on the side of libel (calling a “poll” among your readers is no substitute for a proof, and it seems to me that the results are mixed anyway). NAH and DF put forward some reasonable-sounding argumentation on why the multi-lepton signature is a natural consequence of models on which they (and others) have been working for years. If you are still not convinced you should try to rebut those arguments. Cheers, Ptrslv72

34. dorigo - November 4, 2008

Hello Ptr,

I do speak my mind in this blog, otherwise I would close it. You know there are two distinct papers, and one of them has several authors – so I am not yet sure that one of them does not come up and say, “Well, yes, I did know something about the CDF analysis, but I did not tell my collaborators to avoid influencing them, but I suggested a line of investigation”. I did not explicitly call anybody a liar, but I said it is quite hard to believe in a coincidence.

As for rebutting NAH arguments, I do not intend to do it although, believe me, it would be interesting. It is not just semantics: “lepton jets” are something that is not so hard to imagine; what is striking is instead the combination of lepton jets, long lifetimes (much longer than anybody hypothesizes most of the times in BSM models), and small invariant mass of lepton pairs -a signature which, to be honest, appeared in a paper by CDF authors as far back as in 2005. This much, in the narrow time frame between June (when the analysis got to the ears of all CDF) and October. I think it is a very, very striking coincidence, to say the least. Ok ?

I think people around have already their opinion on this, and anybody can make their own. I wanted to test what people think about this, and indeed many share my views.

My own opinion is simple, and I stated it already. To reiterate: the CDF result leaked in too many ways (some even documented, see Peter Woit’s blog). It is hard for me to believe that the theorists who wrote those papers were not exposed to those news.


35. dorigo - November 4, 2008

Hi Lubos,

my “superficial linguistic analysis” is what it is, NAH’s paper is what it is, and the fact that the CDF result – and drafts of the paper- appeared all around the world months before they did on the arxiv is a proven fact.

You can believe what you like, I have my own opinion. There is no need to call each other names.

About Neal’s comment on PW’s blog: what I found extraordinary is that thirty minutes after Peter publishes his post – which is in turn only minutes after the appearance of the CDF preprint – Neal has an “official” answer to the objections. This, at night time in the US.

Did Neal consult with his colleagues ? I don’t think so. I think his was a rushed comment, and I do not blame him for this – mine was too. I think an official answer takes more time to put together. Hence my comment.

In any case, I am really tired of this issue. If these are roses, they will flourish. If Nima then gets a Nobel prize, I will be happy, not sore. I will still have my doubts, but he will have shown he made good use of whatever information he got, if he got any.

And you are really wrong about me. I am not jealous in the least. I have my own ideas, and I am sceptical. But I wish the best to Nima and to whomever advances science. You should know that, were it for me, the CDF events would have been known to the world much sooner. Secrecy in scientific investigations is bad.


36. Ptrslv72 - November 4, 2008

Hi T.,

to summarize: Weiner, Arkani-Hamed and Finkbeiner (the latter also
on behalf of Slatyer) told you explicitly that they did not know in advance of the CDF results. This covers all four authors of both papers. You say that you are not calling anybody a liar, but still imply that one of them is the mole. It seems to me that you want to have it both ways… Anyway, enough of this: you stated your position quite clearly, and, as you wrote, anybody can make their opinion. Cheers, Ptrslv72

37. dorigo - November 4, 2008

Dear Peter,

yes, let us leave it at that. I had a personal exchange with Doug, and it was perfectly civil. I had a public exchange with Nima which is for everybody to read – I did not call him a liar, he called me brown muck. I had an exchange with Neal, it stopped there. Am I entitled to an opinion ? I think so. Rightly you argue opinions may become libel sometimes. I hope physics remains on the blackboard and on scientific papers and does not venture into justice courts – that would be the end of it. My share of work to prevent that from happening is that I will be more careful with what I write. But my opinions remain.


38. Daniel de França MTd2 - November 4, 2008


Lubos is speaking like that just because he is watching too much TV, seriously. He posted a TV episode on his blog, in which there is a character that speaks like he writes here. I swear this is true.

The name of the show is “Big Bang Theory”, and he is just pretending to be Sheldon Cooper. Don’t you believe me? Just see the 1st 3 minutes of the episode he posted!.


39. Andrea Giammanco - November 4, 2008

I am visiting this blog regularly, in these days, in the hope of finding a comment of the CDF paper based on what *you*, more than anybody else in the blog-world, are most entitled to comment: the experimental aspects.
Ok, reading comments by educated readers about all the theoretical issues connected with the interpretation of those data is instructive and interesting, but many other blogs are doing the same. And some are doing it better.
The added value of your site would be in discussing how the standard sources of instrumental error have been ruled out by the analysts. You are not only an experienced experimentalist, you are also one of the people who built the detector itself, and who attend regularly its meetings.
I’m disappointed that you waste this occasion to contribute to the debate with something really useful (I am not asking you to express an opinion on how fairly the backgrounds were estimated – your colleagues would not appreciate that – but educating all these passionate theorists and curious laymen about how these things are dealt with, in our work in general and in your collaboration specifically).

(Not to mention that I agree with Ptrslv72.)

40. Luboš Motl - November 4, 2008

Dear Daniel,

the Sheldon Cooper character was designed according to my template. That’s why it’s such a popular and charming character. It is not perfectly me but the similarities are surely not coincidental. 😉 On the other hand, most of you on the left-wing blogosphere are over-abundant copies of Leslie Winkle – literally a dumbassery, as Ramona would say. 🙂

At any rate, this has nothing to do with this lepton jets issue and I am really puzzled why did you bring TV into this debate, Daniel! Do you understand these are two different topics?

More seriously, Tommaso, again, there is absolutely nothing rational about your conspiracy theories. N.E.W. has over 1,000 visits a day so it is likely that a few minutes after Woit posted his comment about the CDF preprint, a reader in e-mail contact has contacted Weiner, if it was not he who is checking N.E.W. himself.

It is completely normal that Weiner was checking his e-mail or other forms of contacts and because this accusation that bubbled was so “urgent”, he instantly submitted his “official” statement about it. He can do it because he arguably knows about everything what his collaborators knew because they have worked in a team for quite some time, didn’t they? How could they not know whether other team members know about some CDF events?

The comments that the CDF draft has been available “in the air” or on the Internet for months is irrelevant in comparison with other data on the other side. Weiner, Finkbeiner, and others have been working on a similar model of dark matter for years, see e.g.


Nima Arkani-Hamed has been working on supersymmetry and other relevant topics for decades and he is scanning every paper on hep-th, hep-ph, hep-ex, and a few other archives every day right after the preprints are released. Nima has written dozens of preprints where existing ideas and experimental data are used, combined, and recombined.

It is absolutely logical to add SUSY to the pretty much existing models that evolved from the “exciting” INTEGRAL model by Weiner and Finkbeiner, and it is absolutely logical to derive the collider signatures of such a supersymmetric model. Nima and others have done similar things hundreds of times in cases that were not sufficient for you to invent conspiracy theories.

Best wishes

41. eager2no - November 4, 2008

A new paper with a new model to describe an even that experimentalists have been trying to explain for months!

Then, P. Woit then said that CDF internal papers were publicly open to any one for some time until he told them about it.

Then, someone says why the experimentalists searched for this signal if not know to exist before(!) and why now at the end days of the Tevatron! Should people leave the Tevatron now!?

Of course I don’t buy the idea with a model published 3 weeks before its experimental verification. I am a person who learns from history and I was told in person the J/Psi story!

42. dorigo - November 4, 2008

Daniel, I rather believe Lubos is affected with multiple personalities. He is a quite polite, amicable chap usually. Then, in particular circumstances and when discussing a few topics, he gets in some sort of short circuit, and he gets coprolalic and vitriolic. I appreciate that the former is his real self, and I accept his other occasional bouts as a sickness, for which he should not be held responsible. Or maybe yes: the last comment above, #40, shows he can control himself even when discussing things that usually inflame him. Oh well.

Lubos, thank you for clarifying your thoughts without including various levels of insults to me and my ignorance (which I never denied). Be a good guy here and you will always be welcome, ok ?

Hi eager,

history has the defect to repeat itself time and again. However, I am starting to believe we must keep the option open that the authors were in good faith, all of them. After all, who cares.


43. dorigo - November 4, 2008

Hi Andrea,

thank you for your comment, and of course I agree. I have been rather disappointing in the way I reported about this hot new result. If this was my job I would have no excuse but… This is not my job.

I sometimes get overwhelmed by other things that are more urgent to deal with than updating this site. Discussing in detail what I think of the CDF excess of multi-muon events takes a huge amount of time, because the analysis is very complex and no, I do not have everything at my fingertips all of the time – I need to study, document myself, read, copy, as any other mediocre being.

So please accept my apologies if I disappointed you. I hope I will be able to offer a reparation soon.


44. dorigo - November 4, 2008

Oh, and – Lubos. You must be kidding me. You certainly well know that NEW is closer to 10, 000 visits a day than to 1000. My blog totals about 1300, yours I would guess about two and a half times as many. These figures are not hard to estimate. It fails me why you derate your own public figure by showing you cannot be objective, at times.


45. Yatima - November 5, 2008

Dear Tommaso,

>> And since extraordinary events require extraordinary explanations to be believed, I think we need more than the outrage of a few distinguished theorists to wipe that cloud off our minds.

But the correct citation certainly is that “extraordinary claims require extraordinary evidence” [Sagan]. Extraordinary events however, may require nothing more than selection bias. I’m just saying.

>> I did not call him a liar, he called me brown muck.

I had the impression that the meaning was that “the blogosphere is brown muck”, not you personally.

Best regards,

46. Iphigenia - November 5, 2008

TD said: “However, I am starting to believe we must keep the option open that the authors were in good faith, all of them.”

When everything was on google for months….including, hilariously enough, discussions about the dangers of leaks?!! haha! However, I do believe that three of them were completely innocent.

” After all, who cares. ”

A lot of people care.

I understand perfectly that you are getting sick and tired of this business. But if your suspicions about you-know-who are correct [and — come on! — who can doubt that?] then it is a very serious matter. Do we really want physics to be run like this? We can all get very “realistic” and declare that we don’t care how the truth is found, but I don’t want it to be found in a way that makes me sick. Furthermore, if this sort of thing goes on, it will seriously undermine everyone’s faith in the whole process. It’s highly likely, as a result of this episode, that *every* theoretical paper on this subject that appears in the next few months will be regarded with more or less scepticism, if not contempt. What if one of them actually had the correct explanation?

Anyway, TD, you have no reason to reproach yourself. You have done the community a service.

47. milkshake - November 5, 2008

Lubos personality: The tantrum-prone act is the real persona, the polite tone is the crayons and candies. He will switch back to abuse the moment he determines you are unable/unworthy to be converted into jis groupie.

48. Andrea Giammanco - November 5, 2008

Hi Tommaso,
I understand your point, keeping this blog updated is not a duty nor a “service work”, but I estimate that if you integrate all the time that you spent in commenting your suspicions, justifying your previous comments, finding a diplomatic way to answer to people who felt (legitimately) offended, not to mention that you continued to fuel this unpleasant discussion with your proposal of a poll (!) in this post, well, I bet that in the same time you would have been able to write something interesting about at least one of the four sources of background investigated by Giromini’s group 😉
I have of course no objection if you say that you prioritize real work over divulgating physics on a blog. What I criticize is prioritizing “brown muck” over any of the two.

49. dorigo - November 5, 2008

Andrea, you cannot write a rather aggressive comment and pretend it becomes acceptable because you insert a smiley at the end.
1) how I spend my time is my call, if you are not satisfied I am sorry -really-, but there is not much I can do right now.
2) you already stated your opinion in a former comment above, reiterating it here is not a sign of benevolence.
3) my question in this post aimed at understanding what people thought, because I felt rather uneasy being the only one expressing my views openly. I got what I asked for, now please leave this topic alone, would you ?


50. dorigo - November 5, 2008

Yatima, true, I took the liberty of modifying the saying – which I used in its original form only a post ago below. Maybe NAH did not mean to insult me, but I cannot imagine a non-insulting comment written in a more aggressive way. Doug -one co-author- has been much, much more pacate, and we left the topic with a smile.

Iphigenia, thanks for your comment. I do not know if I did a service to anybody, but I spoke my mind. I wonder how many do the same thing in today’s science business, where people are constantly trying to please and lick, to get better positions and improve their careers.

Cheers all,

51. Timo - November 6, 2008

I am not a physicist, and I really don’t understand most of the nice details in this blog. But I really do enjoy reading – most of the time.
Tommaso, by reading your blog for a longer time by now I have gained to respect you. So much that when I do see you clearly upset, I have the itch that you probably have a very good reason for that, I mean, you might be right in your claims.
However, if I had read the recent discussion from some blog I had not read a lot before, I had felt a bit more uncomfortable. I had wished that there would have been more filtering on personal claims and expression. It just did not quite look professional.
Mind you, I have links to both physorg.com and your blog on my homepage. And this time I happened to read first about this on s
Physorg. So I was happy to see a link to your blog and the interesting news. I was a bit less happy to read how you got upset. I am sad because you have probably now had lots of visitors, but they get to read about this silly argument instead of physics.
Since I have read this blog before, I know you have been upset before, and sometimes you have been wrong.
What I do not understand is this poll. Analyzing their paper can not help you figure out if there was a leak or not: if there are similarities, surely it there is a non-zero probability that there actually is common physics that could explain it? Shouldn’t underlying physics force scientists to reach similar conclusions naturally? For non physicist, that would make common sense. And the physics are somewhat too hard to understand. I understand that this blog is for physicists, but there are still a lot of other readers as well.
Best wishes

52. dorigo - November 6, 2008

Dear Timo,

thank you for your note. Let me answer to a couple of points in good order.

First of all, why did I open a poll on such an issue. It was not exactly a poll in my intention, although I did call it as such. I wanted to understand whether I was the only one, among informed people, who found hard to believe that such detailed predictions for such a non-trivial signature could come out with exactly the timing one would expect from theorists getting to know about the CDF signal when it was made public internally, and working during the summer at producing a tentative model which could fit that in.
My reason for wanting to know other ideas was that if I was really alone I would need to apologize more openly than how I did with the authors. Yes, I can be very wrong at times. Maybe it shows more than with others who express their opinion with more scarcity.
So, the poll had of course no intention to find any truth, as is self-evident to me, but as may be equivocal to whomever gets too much influenced by the way polls are used nowadays (to create consensus).

Second, I was never really upset. Who upset me most in the aftermath of this thread and the former ones was Andrea, whom I consider a friend and who is a regular on this site, and who reproached me for lingering on an issue on which I was wrong rather than discussing details of the physics. I got upset because I am doing my best to produce content here, and if I do not I am the first to regret it, so I do not really feel I need to be patronized about not discussing this or that physics topic.

Now, about the issue of the leak: please let’s forget it. I know there are many people who feel as I do, and many more who think otherwise and who believe it is offensive to publically express one’s opinion on the matter. Too bad, let’s move on. As I said, I do not attach particular meaning to the whole issue. I do not think multi-muons are new physics, and I do believe the whole matter will be forgotten next year. If it turns out I am wrong on this one, well, then we will reconsider the matter.


53. Andrea Giammanco - November 6, 2008

I sincerely apologize. I recognize that I should have expressed my opinion in exactly the same way and tone as Timo, who expressed what I intended to say, but in a much better way.

54. dorigo - November 6, 2008

It’s ok Andrea, my being pissed off was over the moment it started. No apologies necessary, keep bugging me about the content if you feel the need to.

55. Mauro Da Lio - November 7, 2008

I am not a physicist. I am an engineer and perhaps I have a different view.
I understand that physicists like the idea of being able to develop models that later are successful in explaining new findings. I do not subscribe this point completely: sometimes it looks like the will to predict a puzzle with too few pieces. And here we have very few pieces yet.
Unfortunately in modern physics we are facing the limits of knowledge. We see a number of signs with our experiments and we try to infer “what” is causing that.
It is somewhat like to try to explain what is inside a black box by the observation of very few outputs of that box. But even if we could have plenty of information about the outputs, we could never be sure of what is really inside, because we can imagine many possible interiors that produce the same exact signs.
So, let us try to use the same method to find an explanation to the recent facts. The facts are:
1) we have a paper which report a possible new phenomenon;
2) preprints and other info relative to the observations were not so securely protected;
3) a paper, which might explain it, was published three weeks before;
Now these are the facts. We have two “models”. The first model says that paper 3) benefited of some hints. This model is consistent with the facts 1-3 and is a possible interior of the black box. Then we have a second “model” which says that paper 3) was prepared without any knowledge of 2). The second model is slightly better in “fitting” the fact that actually theory 3) is not perfectly tailored for experiment 1). However, it is slightly inferior to the first if one considers the tiny time separation of events 1) and 3).
Can we conclude which is the correct explanation? No, in my opinion.
One might at this point call another argument: the authors of paper 3) say they had no knowledge of 2).
Although I perfectly accept that they can claim that, I think this is not a “fact” but a “claim”. Evaluating this claim as the facts 1-3 would be equivalent to “believe” in something. This is something that a physicist should not ask (“belive on his words”).
So, in my opinion the authors of 3) are allowed to say that they had no knowledge of the CDF experiment. But they should also understand that we cannot weight this claim.
There are two possible explanations and it is not offensive (from this point of view) not to rule out the first “model”.

56. Ptrslv72 - November 7, 2008

Hi Mauro,

your reasoning seems fine to me, but for completeness you should throw in another “fact”:

4) a completely unrelated experimental result, suggesting the existence of some unknown mechanism that produces an excess of leptons, was announced months before the appearance of the paper 3)

Only in this way is the genesis of paper 3) put in the correct perspective. Cheers,


57. Mauro Da Lio - November 7, 2008

Hi Ptrslv72

It is obvious that there must have been at least one source of inspiration (nobody makes unnecessary models).
However, fact 4), strictly speaking, does not prove it was the ONLY source of inspiration.
Unfortunately, there is simply no way to rigorously demonstrate that CDF preliminary data were either known or unknwon (unless we call in arguments like authority, honesty, correctness, etc., which I would not like to see in a debate on physics).

58. Ptrslv72 - November 7, 2008

> (nobody makes unnecessary models).

heh heh it’s obvious from this remark that you are not a physicist… 😉

I would argue however that this was not a debate on physics (I mean, about the validity of some theory or calculation or result). It was a debate on whether NAH et al. had violated an unwritten but widely accepted ethics code, according to which people should not base their research on leaked information (and pretend that they didn’t). Honesty, correctness etc. DO have a place in this.

Anyway, everybody else (starting with Tommaso) seems to have moved on, and so should we. Cheers, Ptrslv72

59. Mauro Da Lio - November 8, 2008

heh heh heh… it is obvious that I am an engineer 🙂
my primary interest is: “will we be ever able to exploit this thing?”

60. Just Studying - November 9, 2008

Well it would be a neat way to walk through walls

61. Hello world! « Curious Ramblings - December 1, 2008

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62. A chat with Arkani-Hamed at CERN « A Quantum Diaries Survivor - December 9, 2008

[…] exploited at the LHC. This caused arguments -better call them exchanges- with Neal Weiner and with Nima Arkani-Hamed (see here for the original epistolary). Nima, in particular, had a remarkable incipit in his […]

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