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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    1















    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

























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      1








      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 2 hours ago









      user6760user6760

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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
            1 hour ago



















          1














          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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            2 Answers
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            active

            oldest

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            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            4














            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
              1 hour ago
















            4














            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
              1 hour ago














            4












            4








            4







            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 1 hour ago









            Dan YandDan Yand

            8,03211133




            8,03211133








            • 1





              I just look up spin so spin can be negative

              – user6760
              1 hour ago














            • 1





              I just look up spin so spin can be negative

              – user6760
              1 hour ago








            1




            1





            I just look up spin so spin can be negative

            – user6760
            1 hour ago





            I just look up spin so spin can be negative

            – user6760
            1 hour ago











            1














            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




























              1














              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


























                1












                1








                1







                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 12 mins ago









                rob♦rob

                39.7k971164




                39.7k971164






























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