505 reputation
17
bio website
location
age
visits member for 1 year, 5 months
seen 20 hours ago

Feb
4
asked Why does the object $\epsilon_L Q_L + \epsilon_R Q_R$ correspond to a 16-component conserved supercharge when we have a Dp-brane?
Nov
7
awarded  Yearling
Sep
17
comment Are there two types of D-term and two types of F-term in SUSY?
Thanks Lubos, this helped a great deal.
Sep
17
accepted Are there two types of D-term and two types of F-term in SUSY?
Sep
17
asked Are there two types of D-term and two types of F-term in SUSY?
Jul
24
comment Why neutrons in nucleus don't decay?
Note: It's not just that energy has to be put into the system. It's that more energy has to be put into the system than the amount of energy released by the system, resulting in a net increase in the energy of the system. If this happens you haven't moved the nucleus to a more stable (lower energy) state, you've moved it to a less stable (higher energy) state.
Jul
24
comment Why neutrons in nucleus don't decay?
@zoran404 So: If you start off with a particular nucleus and you imagine that neutron decay occurs you'll end up with a different nucleus. If the nucleus gives away energy overall, you know it's allowed (we know the original nucleus wasn't at the 'bottom', and we know that we've made it one step closer to the bottom). If the process takes up energy overall, (if the nucleus you end up with has more energy than the starting one) then you know that the original nucleus was closer to the bottom than the end nucleus, and this isn't allowed to happen on its own.
Jul
24
comment Why neutrons in nucleus don't decay?
@zoran404 The reason we 'know' that the neutron is in the lowest energy state (in the example in the link that you provided) is because making it go into any other state would require pumping in more energy than you get back. The principle of minimum energy tells us that systems try and minimize their energy. If decay can only happen if more energy is put in than is released then the system has gained energy overall. Since the nucleus cannot go from a low energy state to a higher one on its own, neutron decay is not allowed in these cases.
Jul
23
comment What is the relation between the representation the Higgs field transforms under, the types of couplings in the theory and Higgs/Coulomb branches?
Page 12 of Samonn's notes (link in original question) tells us that "Moduli space consists of separate branches touching each other at transition point". This implies that we get from one branch to the another via phase transitions and that each branch has it's own phase. However I'm not sure.
Jul
23
revised What is the relation between the representation the Higgs field transforms under, the types of couplings in the theory and Higgs/Coulomb branches?
Spelling corrections
Jul
23
asked What is the relation between the representation the Higgs field transforms under, the types of couplings in the theory and Higgs/Coulomb branches?
Jun
19
accepted Must string models that describe 4d effective field theories always have D-branes that extend in the 4 non-compact spacetime dimensions?
Jun
19
comment Must string models that describe 4d effective field theories always have D-branes that extend in the 4 non-compact spacetime dimensions?
Thank you, I found this helpful.
Jun
19
asked Must string models that describe 4d effective field theories always have D-branes that extend in the 4 non-compact spacetime dimensions?
May
24
accepted If $SU(2)_{L} \times U(1)_{Y}$ breaks to $U(1)_{em}$ when a non-zero mass for the Higgs boson is chosen, why do we still have weak interactions?
May
24
asked If $SU(2)_{L} \times U(1)_{Y}$ breaks to $U(1)_{em}$ when a non-zero mass for the Higgs boson is chosen, why do we still have weak interactions?
May
22
comment Do generators belong to the Lie group or the Lie algebra?
Ah I see. That helps a lot, thanks!
May
22
comment Do generators belong to the Lie group or the Lie algebra?
@joshphysics Sorry to return to this but I believe that my previous comment was incorrect. When we say 'a field, $\phi$ is in the adjoint rep of SU(2)' this typically means that the fields transform as $\phi \rightarrow g \phi g^{-1}$. In other words when we talk about fields and their gauge transformations in physics we take 'representions' to mean the group definition of a representation, not the Lie algebra definition. However when we say, for example, 'SU(N) has $N^{2} - 1$ generators' we actually mean the Lie algebra definition of a generator (as opposed to the generator of a group).
May
19
comment Do generators belong to the Lie group or the Lie algebra?
Excellent, thanks again!
May
19
comment Do generators belong to the Lie group or the Lie algebra?
Incidentally, I was torn about who to click for the accepted answer. Both really helped me out but twistor59 got there first.