3 ms·

> like the 5 sigma result in 2015 Isn't that just an earlier version of the same experiment? Doesn't seem too surprising that a broad distribution has a mean

> like the 5 sigma result in 2015 Isn't that just an earlier version of the same experiment? Doesn't seem too surprising that a broad distribution has a mean shift with a different experimental setup. I'd count this as a repeat of the same experiment. That of course doesn't rule out some flaw in their experimental setup that happens in roughly the same way in each repeat.

gus_massa 7y ago
The mass of the result of 2015 is close to the current claim, so I have to correct may comment and say that it has not disappeared (yet). But they have a 13.45+-.30 MeV result in 2012 with a significance of 3 sigmas [1] and a 12.0+-2.5 MeV result in 2008 (I can't find the significance, it looks like a 2 or 3 sigma) [2]. If it possible to get a false result by chance like 1/20 or 1/100 of the times, but they already got 2 of them. So I'm very skeptical of the new third claim. (Also the story about the protophobic particle is strange. There have been more strange things, but this is strange anyway. And it's also not clear why the protophobicity hides the particle in all the previous electron-positron collision experiments in many other laboratories.) [1] https://www.lnf.infn.it/sis/frascatiseries/Volume56/Krasznahorkay.pdf https://www.lnf.infn.it/sis/frascatiseries/Volume56/Krasznah... [2] http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=39&page=483 http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=39&pag...
- peteradio 7y ago
  Just to play advocate more, if you look at the broad excess in the angular plot in all those papers it shouldn't be surprising that this results in a broad and changing best estimates for mass. So without crunching the numbers, again its possible all these are measuring the same thing with a fluctuating best guess for mass. I think we shouldn't dismiss the latest result due to the previous results. I think we should wonder what could be the systematic issue that could cause this effect without it being new physics. I think the excess in all the experiments will likely have the same root, be it new physics or something else that is not yet understood. So don't count those previous papers against them, those are all measuring the same thing and the convention of physics to match to some theory is causing the precise conclusion to jump around. If you look at the actual raw data the effect is not changing too much.
  - gus_massa 7y ago
    The relevant graph are in the Figure 6 of the first paper and Figure 2b of the second. The idea is to match a simulation of the results you would expect if the new particle has different masses and compare it with the experimental data and see how good is the fit. The horizontal axis is the mass of the hypothetical particle in the simulation, and the vertical value is how good is the fit (lower is better). In both the 17MeV region is out of the interesting region. So if there is an effect, they did a very bad analysis before. I think it's better to wait until another group can independently reproduce the results. It doesn't look too complicated, for someone that has a similar lab. (It's not like the results of the LHC, where the reproduction steps start with: "First dig a 17mi long circle and then call for further instructions." :) Note that to try to avoid false positives, they have two almost independent groups in oposite points of the circle.)

gus_massa 7y ago

The mass of the result of 2015 is close to the current claim, so I have to correct may comment and say that it has not disappeared (yet). But they have a 13.45+-.30 MeV result in 2012 with a significance of 3 sigmas [1] and a 12.0+-2.5 MeV result in 2008 (I can't find the significance, it looks like a 2 or 3 sigma) [2]. If it possible to get a false result by chance like 1/20 or 1/100 of the times, but they already got 2 of them. So I'm very skeptical of the new third claim. (Also the story about the protophobic particle is strange. There have been more strange things, but this is strange anyway. And it's also not clear why the protophobicity hides the particle in all the previous electron-positron collision experiments in many other laboratories.) [1] https://www.lnf.infn.it/sis/frascatiseries/Volume56/Krasznahorkay.pdf https://www.lnf.infn.it/sis/frascatiseries/Volume56/Krasznah... [2] http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=39&page=483 http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=39&pag...

peteradio 7y ago
Just to play advocate more, if you look at the broad excess in the angular plot in all those papers it shouldn't be surprising that this results in a broad and changing best estimates for mass. So without crunching the numbers, again its possible all these are measuring the same thing with a fluctuating best guess for mass. I think we shouldn't dismiss the latest result due to the previous results. I think we should wonder what could be the systematic issue that could cause this effect without it being new physics. I think the excess in all the experiments will likely have the same root, be it new physics or something else that is not yet understood. So don't count those previous papers against them, those are all measuring the same thing and the convention of physics to match to some theory is causing the precise conclusion to jump around. If you look at the actual raw data the effect is not changing too much.
- gus_massa 7y ago
  The relevant graph are in the Figure 6 of the first paper and Figure 2b of the second. The idea is to match a simulation of the results you would expect if the new particle has different masses and compare it with the experimental data and see how good is the fit. The horizontal axis is the mass of the hypothetical particle in the simulation, and the vertical value is how good is the fit (lower is better). In both the 17MeV region is out of the interesting region. So if there is an effect, they did a very bad analysis before. I think it's better to wait until another group can independently reproduce the results. It doesn't look too complicated, for someone that has a similar lab. (It's not like the results of the LHC, where the reproduction steps start with: "First dig a 17mi long circle and then call for further instructions." :) Note that to try to avoid false positives, they have two almost independent groups in oposite points of the circle.)