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2. ### A Predicting the positive parity and zero spin of the Higgs boson?

I read(https://arxiv.org/pdf/1506.05669.pdf) which also exist at https://dash.harvard.edu/bitstream/handle/1/23474113/4596194.pdf?sequence=1&isAllowed=y There is also another interesting paper (https://arxiv.org/abs/1307.1432) in which the Standard Model spin-parity JP = 0+ hypothesis is...
3. ### A Predicting the positive parity and zero spin of the Higgs boson?

Do we expect that parity and spin are conserved in this particular decay? If so can we use the spin and parity of the two photons to predict those for the H boson?
4. ### A Predicting the positive parity and zero spin of the Higgs boson?

Can we predict the positive parity, and zero spin of the Higgs boson from the decay mode: 𝐻 → 𝛾𝛾?
5. ### Help please differentiating this equation from a mechanics textbook

Ya I just did that. It seems like I'm almost arriving at their expression but I can't seem to get the 2 first terms on the RHS. ##\frac{d}{dt}(a^2(\frac{1}{2}\dot{a}^2-ca)=ca(-2\dot{a}^2(1-\frac{1}{2}\frac{\dot{a}}{c})-a\ddot{a}(1-\frac{\dot{a}}{c}))## I am not sure how they arrived at that...
6. ### Help please differentiating this equation from a mechanics textbook

It seems like I'm almost arriving at their expression but I can't seem to get the first few terms on the RHS. ##\frac{d}{dt}(a^2(\frac{1}{2}\dot{a}^2-ca)=ca(-2\dot{a}^2(1-\frac{1}{2}\frac{\dot{a}}{c})-a\ddot{a}(1-\frac{\dot{a}}{c}))## I am not sure how they arrived at that. This is what I keep...
7. ### Help please differentiating this equation from a mechanics textbook

Ya I just did that. It seems like I'm almost arriving at their expression but I can't seem to get the 2 first terms on the RHS. ##\frac{d}{dt}(a^2(\frac{1}{2}\dot{a}^2-ca)=ca(-2\dot{a}^2(1-\frac{1}{2}\frac{\dot{a}}{c})-a\ddot{a}(1-\frac{\dot{a}}{c}))## I am not sure how they arrived at that...
8. ### Help please differentiating this equation from a mechanics textbook

So I tried calculating the derivative now and I'm getting most of the terms (LHS of the equation and the 3 right most terms of the RHS). This is what I have now...

##r=a(t)##
10. ### Help please differentiating this equation from a mechanics textbook

Thanks! Now so I tried differentiating the the first term on the RHS (##a^2(\frac{1}{2}\dot{a}^2-ca+h)##) with respect to time. This is what I got after differentiating this term: ##a\dot{a}^3+a^2\dot{a}\ddot{a}-3c{a}^2\dot{a}+\dot{h}a^2+2ha\dot{a}## It seems to be different from what they...
11. ### Help please differentiating this equation from a mechanics textbook

So I think I'm almost there, but now I'm having a problem with differentiating the the first term on the RHS (##a^2(\frac{1}{2}\dot{a}^2-ca+h)##) with respect to time. This is what I got after differentiating this term: ##a\dot{a}^3+a^2\dot{a}\ddot{a}-3c{a}^2\dot{a}+\dot{h}a^2+2ha\dot{a}## It...
12. ### Help please differentiating this equation from a mechanics textbook

How did you get ##a\dot{a}^3## for the first term on the RHS?
13. ### Help please differentiating this equation from a mechanics textbook

The derivative of ##2af'_2## wrt time is ##2\dot{a}f'_2+2a\dot{f'_2}##, but I'm not sure how to express ##\dot{f'_2}## in terms of ##\dot{a}##, ##c## and ##f'##.
14. ### Help please differentiating this equation from a mechanics textbook

##\dot{f_1}=f'_1(1-\frac{\dot{a}}{c})## and ##\dot{f_2}=f'_2(1+\frac{\dot{a}}{c})##
15. ### Help please differentiating this equation from a mechanics textbook

##\dot{f_1}=f'_1(x_1)\dot{x_1}##. I'm still unable to obtain their equation (equation 2). The last equation is what I attempted on doing.
16. ### Help please differentiating this equation from a mechanics textbook

Ya my mistake, ##\dot{f_1}=f'_1(x_1)\dot{x_1}##. But I'm still unable to obtain their equation.
17. ### Help please differentiating this equation from a mechanics textbook

Yes I've attached the page that I am trying to understand. You are right, ##f_1## and ##f_2## are indeed functions of ##x_1## and ##x_2## respectively (see equation 3.71a in the page attached). I am still however having a hard time to obtain their equation (3.72).
18. ### Help please differentiating this equation from a mechanics textbook

I tried doing it a few times and this is all I get: c(˙f1+˙f2)=a˙a2+a2˙a−3ca2+˙ha2+2ha+2˙af′2+2a˙f′2c(f1˙+f2˙)=aa˙2+a2a˙−3ca2+h˙a2+2ha+2a˙f2′+2af2′˙ Please let me know where I'm going wrong. Thanks