Exam and consultation

Moderators: Konstantin Belotsky, Maxim Khlopov

Exam and consultation

New postby Larisa_MEPhI on Sat 25 Dec 2010 10:49

Good day, Maxim Yur'evich!
As you may know our exam will be 13.01.2011. Usually we have exams at 9-00 Moscow time, but we know that You have another time zone. So we have a proposal to make our exam at 12-00 Moscow time and everybody will be vigorous and not so sleepy. Also we ask You to give us questions for exam or examination cards - as it will be more conveniently for You.
Last edited by Larisa_MEPhI on Mon 27 Dec 2010 12:35, edited 1 time in total.
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Re: Exam and consultation

New postby Maxim Khlopov on Sat 25 Dec 2010 16:06

Dear Larisa,
Usually, the exam starts, when Konstantin Mikhailovich gives tickets and you start to prepare answers to the questions of the ticket. When you are ready, we start videoconferencing, at which you answer the questions of the ticket.
So it is up to you, when you would like to start in order to be ready with answers to 12 Moscow time (for me 12.00 Moscow time would be fine to begin videoconferencing)
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and Happy new year!
M.Yu.Khlopov
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Re: Exam and consultation

New postby Larisa_MEPhI on Mon 27 Dec 2010 12:34

And will we have cosultation the day before exam?
And what about questions for exam?
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Re: Exam and consultation

New postby Maxim Khlopov on Mon 27 Dec 2010 13:08

You can ask Konstantin Mikhailovich Belotsky for the list of questions for exam.
Of course, we can make a consulation before the exam.
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Re: Exam and consultation

New postby Larisa_MEPhI on Thu 6 Jan 2011 18:58

Доброго времени суток, Максим Юрьевич!
Хотелось бы задать Вам пару вопросов по курсу, если не возражаете.

Вы говорили во 2ой лекции про проблему массы нейтрино. Вот что такое Дираковская масса - понятно, а что такое Майорановская - не очень.
И еще. Когда Вы говорите про фамилоны и аксионы, Вы говорите, что "они должны взаимодействовать с ... с константой связи обратно пропорциональной шкале нарушения симметрии ...". Не очень понятно тогда в этом контексте, что такое шкала нарушения симметрии.
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Re: Exam and consultation

New postby Maxim Khlopov on Thu 6 Jan 2011 19:18

Dear Larisa,
I use this occasion to wish you a very Happy new year.
Let's turn now to your questions:
Вот что такое Дираковская масса - понятно, а что такое Майорановская - не очень.
Dirac mass relates right and left handed particles. Majorana mass links left-handed neutrino to right-handed ANTI-neutrino. It is evident that only neutral particles can have Majorana mass, since for charged particles it is prohibited by charge conservation. In the set of elementary particles (quarks and leptons) only neutrino is neutral and can have Majorana mass.
Когда Вы говорите про фамилоны и аксионы, Вы говорите, что "они должны взаимодействовать с ... с константой связи обратно пропорциональной шкале нарушения симметрии ...". Не очень понятно тогда в этом контексте, что такое шкала нарушения симметрии.
Familons and axions are Goldstone particles - they appear in the result of global symmetry breaking: familons due to breaking of symmetry of families and axions due to breaking of Peccei-Quinn global symmetry. Both symmetry of families and Peccei-Quinn symmetry are broken at high energy scale V. It is the inverse of that energy scale 1/V that enters coupling constants of quarks and leptons as m/V (where pending on model m is some combination of quark or lepton masses). In particular, since V>>m, axion coupling is suppressed and people call it "invisible axion".
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Re: Exam and consultation

New postby Larisa_MEPhI on Thu 6 Jan 2011 20:33

Thank You very much for answers! Now it's clear!
Happy New Year for You too! And Merry Christmass!
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Re: Exam and consultation

New postby Maxim Khlopov on Thu 6 Jan 2011 20:55

Merry Christmas to you too!
Regards
M.Yu.Khlopov
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Re: Exam and consultation

New postby Larisa_MEPhI on Mon 10 Jan 2011 13:44

Good day, Maksim Yur'evich!
Could You, please, tell me why do bosons and fermions have different temperatures?
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Re: Exam and consultation

New postby Maxim Khlopov on Mon 10 Jan 2011 14:05

Dear Larisa,
Bosons and fermions have the same temperature in the equilibrium. However, if some species decouple, their temperature can differ from the temperature of plasma and it should be taken into account, as we do in the case of relic neutrinos.
The general formula, given in lectures, takes into account this possibility for decoupled species.
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