Why particle can decay into 2 photons instead of 1 photon?












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I recently read an old physic news about higgs boson was observed to decay into 2 photons and I wondering why it won't decay into 1 single photon with the combine energy of 2 photons?






photons higgs proton-decay







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    2















    I recently read an old physic news about higgs boson was observed to decay into 2 photons and I wondering why it won't decay into 1 single photon with the combine energy of 2 photons?






    photons higgs proton-decay







    share|cite|improve this question

























      2












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      2








      I recently read an old physic news about higgs boson was observed to decay into 2 photons and I wondering why it won't decay into 1 single photon with the combine energy of 2 photons?






      photons higgs proton-decay







      share|cite|improve this question














      I recently read an old physic news about higgs boson was observed to decay into 2 photons and I wondering why it won't decay into 1 single photon with the combine energy of 2 photons?






      photons higgs proton-decay




      photons higgs proton-decay






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      asked 3 hours ago









      user6760user6760

      2,45611736




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          2 Answers
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          The Higgs boson has spin $0$. A photon has spin $1$. The total angular momentum cannot change in the decay, so a Higgs boson cannot decay into a single photon, regardless of the energy. But the total angular momentum of two photons can be zero (if their spins are oriented in opposite directions), so this decay mode can conserve angular momentum.






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          • 1





            I just look up spin so spin can be negative

            – user6760
            2 hours ago



















          3














          No massive particle can decay into a single photon.



          In its rest frame, a particle with mass $M$ has momentum $p=0$. If it decayed to a single photon, conservation of energy would require the photon energy to be $E=Mc^2$, while conservation of momentum would require the photon to maintain $p=0$. However, photons obey $E=pc$ (which is the special case of $E^2 = (pc)^2 + (mc^2)^2$ for massless particles). It's not possible to satisfy all these constraints at once. Composite particles may emit single photons, but no massive particle may decay to a photon.






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          • Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

            – user6760
            50 mins ago













          Your Answer





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          2 Answers
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          2 Answers
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          active

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          active

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          active

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          5














          The Higgs boson has spin $0$. A photon has spin $1$. The total angular momentum cannot change in the decay, so a Higgs boson cannot decay into a single photon, regardless of the energy. But the total angular momentum of two photons can be zero (if their spins are oriented in opposite directions), so this decay mode can conserve angular momentum.






          share|cite|improve this answer



















          • 1





            I just look up spin so spin can be negative

            – user6760
            2 hours ago
















          5














          The Higgs boson has spin $0$. A photon has spin $1$. The total angular momentum cannot change in the decay, so a Higgs boson cannot decay into a single photon, regardless of the energy. But the total angular momentum of two photons can be zero (if their spins are oriented in opposite directions), so this decay mode can conserve angular momentum.






          share|cite|improve this answer



















          • 1





            I just look up spin so spin can be negative

            – user6760
            2 hours ago














          5












          5








          5







          The Higgs boson has spin $0$. A photon has spin $1$. The total angular momentum cannot change in the decay, so a Higgs boson cannot decay into a single photon, regardless of the energy. But the total angular momentum of two photons can be zero (if their spins are oriented in opposite directions), so this decay mode can conserve angular momentum.






          share|cite|improve this answer













          The Higgs boson has spin $0$. A photon has spin $1$. The total angular momentum cannot change in the decay, so a Higgs boson cannot decay into a single photon, regardless of the energy. But the total angular momentum of two photons can be zero (if their spins are oriented in opposite directions), so this decay mode can conserve angular momentum.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 3 hours ago









          Dan YandDan Yand

          8,04211133




          8,04211133








          • 1





            I just look up spin so spin can be negative

            – user6760
            2 hours ago














          • 1





            I just look up spin so spin can be negative

            – user6760
            2 hours ago








          1




          1





          I just look up spin so spin can be negative

          – user6760
          2 hours ago





          I just look up spin so spin can be negative

          – user6760
          2 hours ago











          3














          No massive particle can decay into a single photon.



          In its rest frame, a particle with mass $M$ has momentum $p=0$. If it decayed to a single photon, conservation of energy would require the photon energy to be $E=Mc^2$, while conservation of momentum would require the photon to maintain $p=0$. However, photons obey $E=pc$ (which is the special case of $E^2 = (pc)^2 + (mc^2)^2$ for massless particles). It's not possible to satisfy all these constraints at once. Composite particles may emit single photons, but no massive particle may decay to a photon.






          share|cite|improve this answer
























          • Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

            – user6760
            50 mins ago


















          3














          No massive particle can decay into a single photon.



          In its rest frame, a particle with mass $M$ has momentum $p=0$. If it decayed to a single photon, conservation of energy would require the photon energy to be $E=Mc^2$, while conservation of momentum would require the photon to maintain $p=0$. However, photons obey $E=pc$ (which is the special case of $E^2 = (pc)^2 + (mc^2)^2$ for massless particles). It's not possible to satisfy all these constraints at once. Composite particles may emit single photons, but no massive particle may decay to a photon.






          share|cite|improve this answer
























          • Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

            – user6760
            50 mins ago
















          3












          3








          3







          No massive particle can decay into a single photon.



          In its rest frame, a particle with mass $M$ has momentum $p=0$. If it decayed to a single photon, conservation of energy would require the photon energy to be $E=Mc^2$, while conservation of momentum would require the photon to maintain $p=0$. However, photons obey $E=pc$ (which is the special case of $E^2 = (pc)^2 + (mc^2)^2$ for massless particles). It's not possible to satisfy all these constraints at once. Composite particles may emit single photons, but no massive particle may decay to a photon.






          share|cite|improve this answer













          No massive particle can decay into a single photon.



          In its rest frame, a particle with mass $M$ has momentum $p=0$. If it decayed to a single photon, conservation of energy would require the photon energy to be $E=Mc^2$, while conservation of momentum would require the photon to maintain $p=0$. However, photons obey $E=pc$ (which is the special case of $E^2 = (pc)^2 + (mc^2)^2$ for massless particles). It's not possible to satisfy all these constraints at once. Composite particles may emit single photons, but no massive particle may decay to a photon.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 1 hour ago









          rob♦rob

          39.7k971164




          39.7k971164













          • Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

            – user6760
            50 mins ago





















          • Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

            – user6760
            50 mins ago



















          Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

          – user6760
          50 mins ago







          Massive particle as in fermion with half integer spin right, so it have to decay into some other particles on top of a photon to conserve energy and spin momentum is this what you are saying?

          – user6760
          50 mins ago




















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