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A A 6th force of nature?

  1. Feb 13, 2017 #1

    Chronos

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    This paper; https://arxiv.org/abs/1702.03050, Experimental demonstration of a fifth force due to chameleon field via cold atoms, by Zhang claims detection of yet another 5th force of nature. I recall a similar claim from last year by Jonathan Feng, et. al.; https://arxiv.org/abs/1608.03591, Particle Physics Models for the 17 MeV Anomaly in Beryllium Nuclear Decays. I am unable to discern if, or how these two claims might be linked. Apparently the force reported by Feng is thought to be related to dark matter, whereas the force reported by Zhang is alleged to be related to dark energy. Very convenient, solving both mysteries in 2 fell swoops. Almost sounds too good to be true - which is obviously a difficult impression to avoid. The Feng paper made the pop sci circuit pretty quickly. I've not yet seen any feedback on the claim by Zhang, but it would be quite surprising if it escaped notice. Perhaps one of our resident particle physics experts can shed some light on just what the heck is going on in the usually plodding world of hep.
     
    Last edited: Feb 13, 2017
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  3. Feb 13, 2017 #2

    jambaugh

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    Speaking not as a particle physics expert but rather addressing more general aspects of physics research, I would first point out that the arxiv.org site is a pre-print archive and submissions are not necessarily peer reviewed or even necessarily submitted to journals. I would be very wary of any extraordinary claims until such an article has been through that screening process of peer review.

    Addressing the article specifically, I see the majority of the article discussing theoretical framework and very little on the specifics of the procedure, most especially I see no analysis of error, or uncertainty. How many trials did they carry out? How did they exclude more mundane effects? Etc.
     
  4. Feb 13, 2017 #3

    Chalnoth

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    Zhang's cold atom paper seems very suspicious to me. I'd definitely want independent confirmation. There have been a lot of claimed detections of a fifth force, and they generally don't pan out. A single-author paper claiming an extraordinary and novel experimental result is extremely likely to be completely wrong.

    As for the Feng paper, it's definitely on more solid footing. But it's still a theoretical paper proposing a model to explain a single experimental result. There would need to be independent confirmation to confirm the model, and the fact that the paper suggests just such an independent test of their model is a positive indication of the quality of the work. But it's still speculative: most such models, even well-conceived ones, are wrong.
     
  5. Feb 13, 2017 #4

    Chronos

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    Yes, jambaugh, it hasn't yet hit the journals, but, it is not unusual for papers coming out of China to ride the slow boat. This appears to be his first time on arxiv. His prior papers have appeared in Chinese Physics B, so I would expect the same for this one. The experimental setup is described in figure 1 at the end of the paper. I too do not see any raw data, error bars, etc., which strikes me as something likely to draw the attention of a referee. I try to resist the temptation of discussing unvetted papers, but, this one got the better of me. I too will be interested to see if/how it fares.
     
  6. Feb 15, 2017 #5
    I'm a bit surprised there hasn't been more reaction to this paper, if only to refute it. As far as I can see, Zhang carried out an experiment suggested in the literature, but the results appear to conflict with other investigations of the chameleon field, which found nothing in (I think) the same parameter space. On the other hand Zhang does appear to have measured _something_.
     
  7. Feb 15, 2017 #6

    Chalnoth

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    It's been five days. These things take time.
     
  8. Feb 18, 2017 #7
    Evidently so.

    Incidentally this H.-C. Zhang does appear to be the lead author in the article's reference 18 (Opt. Commun. 282, 3278–3281 (2009) ), also using rubidium atoms.
     
    Last edited: Feb 18, 2017
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