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B Decays affected by all new particles/fields?

  1. Jan 31, 2018 #1
    In the November 2017 Sci-Am article "Chasing Beauty" (about LHC), it says:

    "The rules of quantum mechanics tell us that what happens in nature is driven by the net contribution of all the valid diagrams we can draw, although the simplest and most obvious have the greatest weight. Hence, all these possible decay paths should play a role, and we must account for them in the calculations we make predicting the rate of the decay, the trajectories of the products and other particulars. In other words, even when a particle decays in a normal process involving only conventional members of the Standard Model, it feels the effects of every possible particle out there.

    Therefore, if a measurement of a decay disagrees with our calculations based only on the Standard Model ingredients, we know that something else must be at work. This fact is the guiding principle behind LHCb’s strategy of indirect searches for new particles and new physics. Because these new particles would be virtual participants in every decay that we measure, the mass of the particles we can detect is not limited by the energy capacity of our accelerator. In principle, if we studied the right decay processes with enough precision, we could observe the effects of particles even heavier than those that can be created and detected within ATLAS and CMS."

    1. Questions.. for decay scenarios like the following:

    Does the presence of supersymmetric particles for example affect it too? Or do you have to do specific experiments to measure other contributions?

    2. What decay scenario experiments where you can detect the presence of all known particles in the universe?

    3. Can all the particles and even possible dark matter forces also affect the decays in any decay experiments?

    4. If yes.. are there nothing that won't affect the decays?

    5. If yes, that means we already have constrains of all new particles that can exist?

    6. What if there were unique non-gauge non-SM fields that won't change the decays.. is this possible?

  2. jcsd
  3. Jan 31, 2018 #2


    Staff: Mentor

    Sure. If there are supersymmetric particles they affect every decay. In fact, every particle influences every decay if it interacts with other particles in any way. The question is just how much.

    In general physicists look at rare decays for these studies, as a small contribution from supersymmetry (or whatever else there might be) is easier to find if the known processes are rare as well.
    For all hypothetical particles where someone spent time to calculate exclusion limits, yes.
    I don't see how this would work.
  4. Jan 31, 2018 #3
    Ok. Got it. thanks.

    1. How about the Inflaton field/particle.. it also showed up in decays? Is there a feynman diagram for it?

    2. How about the Bohm quantum potential.. does it show up in decays?

    3. Let's say there were dark matter chemistry ruled totally by dark matter field/forces that doesn't interact at all with our visible Baryonic EM, Weak, Strong forces/field.. would it also show up in decays? This is provided there is not even any dark matter Higgs-portal scenerio, where dark matter interacts with the Standard Model fields via the Higgs boson.. I supposed if there is a portal, then it should show up in decays... so I'm asking what if there is not even a higgs portal.. and it interacts only purely via gravity, would this still show up in decays? If yes.. I can't find any feyman diagram of decays for dark matter via gravity interaction only can you please share any? thanks.
  5. Jan 31, 2018 #4


    Staff: Mentor

    Things connected to inflation are expected to be way too heavy to have a measurable impact on particle decays we can study.
    There is no such thing in QFT.

    Technically gravity is an interaction that would still lead to some interaction, but that would be at least 40 orders of magnitude too weak to be measurable. You can draw loops with gravitons.
  6. Jan 31, 2018 #5
    That means if dark matter connection with our baryonic universe is only through gravity.. there is no way to detect dark matter by any decay processes or pathways, right...

    unless you can drive a portal somewhere in the middle so you can bind our baryonic matter with a possible dark matter chemistry.. this is logical.. please share papers related to this.. I find an article in https://phys.org/news/2017-03-portal-unveil-dark-sector-universe.html


    but axion is too simplistic.. what's the complete list of mechanisms... and what's the most complex mechanism already written out there? thanks!
  7. Jan 31, 2018 #6


    Staff: Mentor


    An arXiv search should find the relevant articles, and the articles they cite can be interesting as well.
  8. Feb 1, 2018 #7
    Thanks. I didn't know there were hundreds of references about it at arXiv.. I was relying on google or news outlets for the more popular papers. It would be interesting read but I don't know if I can read each of them. Maybe will just browse the abstracts. I supposed all of them were peer reviewed (by each other? hmm...)
  9. Feb 1, 2018 #8


    Staff: Mentor

    If they are published later, most authors add the publication details on the arXiv page. Various theorists don't bother with the formal publication process, however, if no co-author needs to look for publication counts. The other experts read the arXiv versions anyway.
  10. Feb 2, 2018 #9
    There are just too many papers about "dark matter portal".. I reached 200 and it never seems to end. They mostly deal with unstable particle like Heavy quarks or massive ones beyond LHC being portal to the dark matter in some decay process. No problem about that.. but I'm just wondering.. why is dark matter even ruled by our Quantum Field Theory.. won't it be possible we only have in common with dark matter via General Relativity while the dark matter "substance" (or whatever) doesn't use quantum field theory or quantum mechanics but by another principle altogether?
  11. Feb 2, 2018 #10


    Staff: Mentor

    I don't see how this would lead to a consistent world. How would you describe interactions of this dark matter?
  12. Feb 2, 2018 #11
    If quantum field theory is just lower energy limit of something else.. then perhaps dark matter has more complete dynamics or use beyond quantum field theory principles.. what if we have to understand first the complete quantum theory enhancement to understand dark matter?
  13. Feb 2, 2018 #12


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    that's not qft, that's supposed to be the standard model... and of course it is as it has a cut-off at the planck scale.

    So DM uses beyond the standard model principles but in order to be detected it has to interact somehow with matter (very weakly). We know it exists from gravity but we can only search for it using our matter particles. You can build hundrends of alternatives that aim to extend the standard model such that it can incorporate dark matter in different forms.
  14. Feb 2, 2018 #13
    Maybe the language is "Quantum Mechanics is limiting case of Quantum Field Theory"... and "Quantum Field Theory is a limiting case of <insert future version of enhanced QFT>? What synonym for "limiting case" to describe the idea?

    Is there at least a paper that summarizes or list the hundreds of alternatives instead of hundreds of papers? Maybe someone can summarize them in one article. It should be interesting to hear the different proposals.

    Is it possible we can only understand dark matter after understanding quantum gravity which comes from rewriting quantum theory and spacetime as per Lee Smolin language? Any reference about this? I can't seem to find this in the several hundreds of "dark matter portal" papers..

    Also I'm looking for any reference that explores the idea that a dark matter subsector contain conscious substance.. I know many hate this word but you have to include ALL possibilities if you want to nail it. After the dusts settle.. who knows.. this may even be a the key to all.. that's why I was saying quantum field theory may not be adequate.
  15. Feb 2, 2018 #14


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    I am not a theorist, but I suppose that quantum gravity should also be a QFT, as it's quantum and relativistic - but maybe that's a word pun. Someone with more insight could answer better.

    I am not aware of any such paper, but IMO I find it unlikely because it would have to be extremely large. DM for example is a point supersymmetry could aim to solve, and there is not really 1 model of supersymmetry as there are assumptions people make or they get new information from actual experiments (several models are proposed, rejected by experiment, re-calculate stuff and return, and so on)...
    DM could also be explained by cosmological axions.
    The PDG is a place to look for reviews that contain a lot of such information (yet I doubt it can have them all) or the reviews from the specific theories that address the problem. http://pdg.lbl.gov/2016/reviews/rpp2016-rev-dark-matter.pdf

    Maybe (sorry I don't know Smolin's language)... quantum gravity is for example searched for at LHC, when they look for the creation of Quantum Black Holes (QBH) or extra dimensional theories.

    I don't understand what you mean by conscious substance. It's not magic if that's what you mean. It's there and interacts with matter and played some role in how the matter evolved (by how it affected the gravitational evolution of the Universe). The question is if it interacts with any other mean that could let us detect it. Answering "no" you take a lot of its interest away, because it becomes untestable.
  16. Feb 2, 2018 #15


    Staff: Mentor

    It doesn't matter, as we are talking about low energies here.
    Do you also want to consider the possibility that dark matter is made out of invisible unicorns?
    This is just nonsense.
  17. Feb 2, 2018 #16
    At low energy.. there is just no substitute to quantum field theory? Even if quantum gravity is eventually formed by another theory where general relativity and quantum field theory are just emergence?


    I didn't mean the entire dark matter is composed of conscious substance... in the dual component (see above at google), dark matter could be composed of non self-interacting (such as WIMPS) and some self-interacting.. and the self-interacting component could be composed of say 85% nonconscious particle and 15% conscious substance. This is not refuted by any data so far observed right? But I don't want to talk about this as this is not popular yet. Just making the point the existing data has not constrained this possibility yet... unless you have arguments and data that put constrains on it so much it can't just happen? I want to be convinced it is nonsense so I can forget about dark matter being part of it.

    Btw.. In LHC and elsewhere.. What's the constraints on the dark matter portal concept? What future accelerators are being planned to test it?
  18. Feb 3, 2018 #17


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    Can you please define what's a nonconscious particle and what is a conscious substance?
    Because, at least the way I understand it, consciousness is not well a defined or measurable concept (it's philosophically debatable) to give it as a property to the matter.

    That's a false argument. If you don't define what your "observable" means and how it's to be interpreted in a measurement, it is scientifically irrelevant and no data will be ever able to reject or prove it. It's the same reason why science was, is and will never "search for the god". It's not meant to/built to do that.

    it won't be...

    data will never constrain that possibility either, because it's an argument raised in an unscientific manner.

    I don't care if it's nonsensical or not. I am pretty sure that putting "consciousness" in the game is making it unscientific.

    for which model?
    Axions are searched for at CAST.
    A relatively-large fraction of supersymmetric model parameter space has been ruled out by experiments performed at ATLAS and CMS.
    Other exotic searches (QBHs, Extra dimensions, new bosons etc) are also rulling out models that could be connected with DM.
    The best way to find some of those is again the pdg review.
  19. Feb 3, 2018 #18
    Sentient Substance being something fundamental like electron and based in the dark matter subsector and it's linked to our body giving us qualia. Hmm.. I know this can violate forum rules so let me stop at this point.. sorry...

    Ok, understood. I won't repeat it.

    Let's just stick to ArXiv or peered reviewed works and wait for the authority to announce solution to the dark matter puzzle. I'm awaiting the Axions results.. when will they be announced.. if there are no axions.. what are other good mainstream candidates of DM?

    I need to know the following which I asked earlier that was not addressed (maybe mfb hasn't logged in yet).

    At low energy.. there is just no substitute to quantum field theory? Even if quantum gravity is eventually formed by another theory where general relativity and quantum field theory are just emergence? What are the experts thoughts on this?
  20. Feb 3, 2018 #19


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    The fig. 61.1 shows the exclusion regions for axion masses+couplings to photons.
    For cold dark matter candidates, the exclusions at fig. 61.3 are more relevant, than the solar axions the CAST is looking for.

    Other candidates for DM that have been searched for are the LSP that are predicted by supersymmetric models.
    Fig. 26.1 shows the excluded regions in the space of cross section vs WIMP mass, which each experiment didn't find any WIMP [e.g. the ATLAS result excluded the high mass WIMPs >100GeV with low-cross sections given the pMSSM model].
    Another example from ATLAS is this search https://arxiv.org/abs/1710.11412 in which they also ruled out the lower-mass particles with cross-section to nucleons above 10^-42 cm^2 (Fig.7) or this https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2016-18/ (Fig.6)...

    Black holes according to the review are also a candidate but they are not really very interesting, as MACHOs (MAssive Compact Halo Objects) which could be part of the dark matter population are not that many (if I remember well).

    I said that quite a few times: the candidates are many (I said susy but susy has like the neutralinos, squarks, gravitinos, blah blah it can possibly have axinos etc), they get refreshed every now and then to take into account new search limits.

    The QFT we have works well at the energies probed today, and there's no reason to substitute it (in fact we can't do it without a clue). The same is true for the Standard Model. We see it has some aspects that don't work nicely (e.g. the Dark Matter), but there is a plethora of models that extend it - one can search for those model predictions, but up to now the Standard Model is standing high (with only a few indications of failure).
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