What is Weak force: Definition and 64 Discussions

In nuclear physics and particle physics, the weak interaction, which is also often called the weak force or weak nuclear force, is the mechanism of interaction between subatomic particles that is responsible for the radioactive decay of atoms. The weak interaction participates in nuclear fission, and the theory describing its behaviour and effects is sometimes called quantum flavourdynamics (QFD). However, the term QFD is rarely used, because the weak force is better understood by electroweak theory (EWT).The effective range of the weak force is limited to subatomic distances, and is less than the diameter of a proton. It is one of the four known force-related fundamental interactions of nature, alongside the strong interaction, electromagnetism, and gravitation.

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  1. G

    I W boson and weak decay

    Hello everyone I have been following Fermilab presentations by Dr Don Lincoln for some years. Recently he did a deeper review into the four fundamental forces. He explained why the weak force is relatively weak. The explanation given was that the “normal” mass of the W boson is relatively high...
  2. AdvaitDhingra

    B Is Z0 Particle Real Without Flavor-Changing Interactions?

    If there are no flavor changing z0 weak interactions, how do we even know that the particle exists? I thought that we could only tell which particle was exchanged by the particles it decays into. Is this wrong?
  3. SamRoss

    I How is the weak force related to a change in velocity?

    Hi everyone, The four fundamental forces are gravity (I understand that G.R. does not look upon gravity as a force but I'm not worried about that here), the Lorentz force, the weak force, and the strong force. I'm familiar with the inverse square law for gravitation and the Lorentz force...
  4. LuisBabboni

    I Why is the weak force a force?

    Hi! I could understand gravitational force as a force that move mass. I could understand electromagnetic force as a force that moves chaerged particles. I even could understand strong force as a force that atrack protons I could not understand the moment of what weak force changes. The moment...
  5. Lucasterre

    Weak Force Weapon Effects on Wall Elements

    Hello, I am a creative scifi writer and i only have basic quantum physics knowledge, if someone could answer my question please. I was wondering some type of weapon that uses weak force, therefore it would promote distorcions at weaf force field causing interaction with atoms My question is, if...
  6. DaTario

    I On the weak force and beta decay

    Hi All We know that beta decay is and ejection of an electron from nucleus, making a proton turn into a neutron (and a neutrino). Is it correct to say that is the weak force responsible for the increasing in the distance between electron and proton during this process (since the feel atracked...
  7. DHO232

    I Does a photon experience time while interacting with the weak force?

    Long time reader, first time posting here in physics forums. I know that according to relativity photons have no proper time. I also know that a photon of sufficient energy can interact with a nucleus's nuclear force via the weak interaction resulting in pair production. I was looking at a...
  8. M

    A Reference for the A field of the Weak Force

    A reference please to a review paper, textbook, or website for an expression, or development of an expression for the field in Electro weak, similar to the A field in EM.
  9. F

    A Relation between chirality and spin

    When learning about chirality I was very surprised to find that for QED and QCD the decay modes that would produce 2 particles with the same chirality had a Matrix Element of 0, which I took to mean that angular momentum was being conserved. Even the W only decay into RH antiparticles and LH...
  10. J

    A Nuclear Processes in Other Universes: Varying the Strength of the Weak Force

    This relates to the anthropic principle and the multiverse. Nuclear Processes in Other Universes: Varying the Strength of the Weak Force https://journals.aps.org/prd/pdf/10.1103/PhysRevD.98.063014 Nuclear processes in other universes: Varying the strength of the weak force Alex R. Howe, Evan...
  11. C

    I Measuring characteristic time of strong and weak interaction

    Consider a scattering between two particles a and b that produces two particles c and d: d is stable, while c decays in two other different particles e and f. The first interaction is by strong force (time of interaction ##t_1\sim 10^{-23}s##, which is also the time of generation of c and d)...
  12. C

    I How good is this PBS video at explaining weak hyper-charge?

    Specifically this one: I've been asking several question's about the weak force to my professors, and both on here and PhysicsSE and it seems impossible to get a consistent answer as to what weak hypercharge, weak isospin actually are with any degree of physical-ity. So I suppose this thread...
  13. C

    I The weak force as an attractive force

    Hi all, how much merit does this answer have on Quora? There also an identical answer on Physics Stack Exchange so it'd be nice to confirm or deny the validity of these. Thanks!
  14. K

    Nuclear Weak Force & Strong Force: Intro Recommendations

    Any recommedations for intro into the weak force? Also ones for the strong force?
  15. H

    I Is the strong nuclear force stronger than the weak force?

    I've heard that the weak nuclear force is stronger than the electromagnetic force at distances of 10^-18 m. I've also heard that the strong force becomes repulsive at a distance of 0.7 fm. So if two quarks got to a distance of <<10^-18 m which force would win, the strong force or the weak force?
  16. A

    B Weak nuclear force - circumstances in which it is manifested

    I have a glass of water at room temperature. The electromagnetic force is at play between the electrons and nucleus of the atoms, the strong nuclear force is at play holding the nucleus together, the force of gravity weak as it may be is at play between the various particles - electrons, quarks...
  17. A

    I Weak force - only free neutrons decay?

    Reading this article - http://hyperphysics.phy-astr.gsu.edu/hbase/particles/proton.html#c4 there is a statement - "A free neutron will decay with a half-life of about 10.3 minutes but it is stable if combined into a nucleus." So is it only free neutrons that decay into protons? In...
  18. C

    B P violation in weak force & BSM

    some inquiries 1. Is it possible parity being violated by the weak force is because of further symmetry breaking of SU(2)xU(1) (besides the higgs field) ? Any papers about this? 2. I read in wiki that that mirror matter can recover the symmetry. What else (beside mirror matter) could restore...
  19. C

    B Weak force symmetry broken above 250 GeV?

    I'm reviewing this book Warped Passages by Lisa Randall and a sentence caused me some incomprehension. Somewhere in it she stated: "The weak gauge boson masses tell us the precise value of the energy at which the weak force symmetry is spontaneously broken. That energy is 250 GeV, the weak...
  20. Q

    A Do the weak isospins of the w1 and w2 combine?

    Do the weak isospins of the w1 and w2 bosons combine as their fields combine?
  21. Samia qureshi

    B Understanding the Weakness of Gravity and its Role in the Universe

    If gravity is a weak force , then How it holds planets , stars and galaxies together ? let me know if i am right..? Gravity only attracts there is no negative version of the force to push things apart and while gravity is powerful enough to hold galaxies together, it is so weak that you...
  22. tzukishiro

    I Why is the weak force 10^-7 times the electromagnetic force?

    In the case of two protons in the nucleus. I've seen charts with that info, but I don't know how... How can I calculate that ratio? I've looked everywhere, and I can't find anything... Thanks
  23. Ryan Reed

    Why does the Weak Force only interact with certain handedness?

    Why does the weak force only interact with left-handed particles or right-handed antiparticles? And does this mean that the particles that don't have those properties won't decay?
  24. Jamie Harper

    Why do we believe gravity to be a weak force....?

    So - this may sound like an easily answered question - but with push-back on my part I hope I can get to the real crux of what I'm asking, in any replies you might be kind enough to provide. I hope the answer is not, eventually, simple. The crux of my issue is this: Why do we believe gravity...
  25. Yohanes Nuwara

    What is the entropy of weak and strong force?

    What is the entropy of weak and strong force? Can we determine their entropy? If so, I would like to know the formula of determining this. Thanks:wink:
  26. AlanKirby

    Why can only the weak interaction change quark flavour?

    Hi there, so my question is as follows. I understand that only the weak interaction can change the flavour of a quark, but why? Idea 1: It's due to the change in flavour also meaning a change in mass, thus a massive exchange particle is needed (gravity is negligible so forget the massive...
  27. V

    Dark matter annihilation into gamma rays

    This question straddles this forum and the "Beyond the Standard Model" one a bit, so if a mentor thinks it belongs better elsewhere, please feel free to move it. I've seen references in the "popular science" press about the possibility of indirectly detecting dark matter by looking for gamma...
  28. A

    What were the clues that the weak and EM force are the same

    Hello, I've been reading a book on particle physics for the general audience, and as you might expect, I was left with a slew of nagging unanswered questions. There was a chapter on gauge symmetry where the author described that the weak and the EM forces are the same force at some energy...
  29. B

    The weak force, first step of nuclear fusion in the Sun

    Hi. I need help please with a textbook illustration that has confused me. Is the caption a typo? Should be "neutrons into protons" instead? Thanks.
  30. A

    What is the reason for weak force?

    what property of elementary particles is reason for weak interaction? what I mean is as color charge is reason for strong force ,as electric charge is reason for EM force and as mass is reason for gravitational force what is reason for weak force?
  31. MalachiK

    Does the photon have direct interactions with the weak force?

    Hi guys, Could someone with a better understanding of the standard model answer a question about the weak force? In a class I'm teaching, a question in the textbook asks if photons feel the weak force. My first thought was that it's fermions that feel the weak force and therefore the...
  32. N

    What are the force laws for the strong and weak nuclear forces?

    Hello! I have a question that has been bothering me for some time, and I thought this would be a good place to ask. This is my first posting on PF as well, so I hope this is well placed. There are force laws for the coulomb attraction and gravity. Are there similar force laws that can be...
  33. J

    Weak Force - in what sense is it a force?

    Hi, I don't know very much about the weak force, but gravity, EM and the strong force all seem to apply an actual F = ma type of force (at least, I think the strong force does). But my limited knowledge of the weak force is just that it is involved in radioactive decay. Maybe this is why some...
  34. A

    Why is weak force short range action?

    In Deep Down Things, an excellent book of B Schumm, at page 288, he explains that the weak force is short range because the Weak quanta have a large mass. Using de Broglie wavelength relation: Lamda = h / p, he gets a wavelength of 10 ** -18 m, and he concludes that this is the W quanta range...
  35. J

    Weak force coupling to left-handed particles

    The W couples to left-handed particles only. What about the Z? Is it the same? Thanks in advance!
  36. S

    Do baryons only decay via the weak force?

    Provided they aren't in an excited state (which would allow a decay via EM or strong). I had a question asking why the neutral lambda particle, consisting of uds quarks, has a lifetime characteristic of the weak. The answer being that it must decay via the weak to change the s-quark flavour into...
  37. dbmorpher

    What is the Weak Nuclear Force?

    I know there are four different forces in the universe and they all affect us. I know that gravity is the force of objects' mass interacting I know electromagnetic is the force carried by photons and is the cause of electromagnetic waves I know that the strong nuclear i responsible for the...
  38. C

    Two Questions: Yukawa Potential and Weak Force

    1. Yukawa Potential So reading about the yukawa potential I notice that the constant k is related to the inverse of the effective distance of the force from what I've been reading. Thing is everything I read about the strong force states it has infinite range but simply has a maximum potential...
  39. PerpStudent

    Is the weak force really a force ?

    Is the weak force really a "force"? I have seen that gravity, electromagnetism and the strong force are described by physicists in detail in the sense that specific things can be said about what is attracted and/or repulsed and under what circumstances these forces are manifested. All we ever...
  40. G

    The strong force and the weak force

    I'm still highly confused about the weak force. Every time I read about it I get something along the lines of it is responsible for beta decay which to my understanding is when a proton or a neutron exits from the atom's nucleus. One thing I have trouble understanding is that if the strong...
  41. R

    Answer:Identifying Strong or Weak Force Interactions

    Strong or weak force?? Homework Statement So all I want to know is how you tell if it is a strong or weak force interaction. e.g. K^+ = pi^0 + pi^0 + pi^+ (all mesons) So i determined that the energy was concerved: 493.7-135-135-139.6=84.1MeV baryon and Lepton numbers are also...
  42. A

    Does the weak force violate conservation of charge?

    Dear Physics Forum, I am a little confused about conservation of charge vs. charge conjugation. I'm reading David Griffith's book "Intro. to Elementary Particles"... pg. 81 "All three interactions (weak, strong, EM), of course, conserve electric charge. In the case of weak interactions...
  43. N

    How can we unify electromagnetic force U(1) and weak force SU(2)?

    Please teach me this: How can we unify electromagnetic and weak interactions?Is it correct that the SU(2) symmetry(flavor symmetry of fermions) is spontaniously broken(by Higgs Field) and the symmetry(be broken) ''become'' U(1)xSU(2) symmetry that is the symmetry of electroweak interaction...
  44. A

    Weak force and axial vector coupling

    Hi physics forum, I have been reading David Griffith's book "intro to elementary particles" and he describes the decay of the pi-meson as "pure axial vector" Can someone tell me what this means, in terms of the weak force vertex consisting of this factor γu(1-γ5) Thanks, Mark
  45. A

    Weak force vertex factor V - A

    Hi forum, The weak force vertex factor is γu(1-γ5). Am I right that the axial component only couples to left handed fermions? Does the vector component couple to both left and right-handed fermions? Thanks, Mark
  46. G

    Is gravity a weak force compared to other forces in the universe?

    Why is gravity thought to be a week force? I would agree that at the surface of our Earth it would appear to be week, after all we can stand on the surface of the Earth without risk of being pulled into it core. But a black hole is another kettle of fish altogether, it's almost an atomic...
  47. J

    Weak force: CP yes + P no -> C no?

    Hi, If the weak interaction obeys CP symmetry but violates P symmetry does that mean that it must also violate C symmetry? John
  48. M

    Parity Violation of Weak Force - Wu et al.

    I have read about Wu et al. and their experiments with Co 60 that showed that the weak interaction violates parity. I don't quite get it tho. 6 So they aligned Co atoms in a magnetic field. Some of the nuclei decay and emit neutrinos and electrons. It was observed that an equal number of the...
  49. Simfish

    How exactly does the pion decay through the weak force?

    So the pion(+)n is made up of an up quark and a down antiquark. And somehow, it emits a W+ boson, which then turns into a muon and a muon-neutrino. From the Wiki article, "W bosons can decay to a lepton and neutrino or to an up-type quark and a down-type quark." Does this mean that the...
  50. J

    A couple of questions about the weak force.

    Is the weak force responsible for all radioactive decay, or just beta? If it is also responsible for alpha and gamma, how does it work? If not, what causes the other two? (Also, related to this, I know that alpha radiation is two protons and two neutrons being expelled from the nucleus, and...
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