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Dear All I am trying to derive the equations of the attached paper ( In homogeneous dark energy). I am wondering why did he split the second term as 2 terms in equation 8. I just write it as the first term!

sure i will. Thank you

Mathematical Physics, Mainly Those related to Gravity. And you?

Hi I am a phd student i am taking an astrophysics course we are using a book for Hansen and Also a book for Dina Prialink

Dear All I have a project related to the early universe and general relativity. Can anyone suggest me a book to start with? Thank you

Dear All It is known that pontryagin densities are defined in even dimension space, let's say i am concerned with 4 dim space time. We also have a certain group G. What is the formula of pontryagin densities for arbitrary group? Larger group?

Ther is also a book for John David Brown. It is interesting too.

I will download it to, i also find the book of Steven Carlip interesting too! Thank you for your time.

Thank you haushofer i will download the book and have a look on it.

Dear all can anyone help me to understand why gravity in 3 dim doesn't have local degree of freedom. How can i compute the degree of freedoms for gravity in and dimension D. If i consider massless gravity in 3d is the graviton propagating

Hi again no i mean in 1+2 space yes i know that the dual of a k vector is N-k. But am applying it to N= 2+1 space, i am wondering if the dual of the field strength which is a 1 form is the same as the gauge field since both are 1 form in this special 1+2 space. Thank you again

Dear all I have a question is the dual of the field strength ( of abelian gauge theory) in 3 dimensional space the same as the gauge field? I have a formula for the dual field strength and am trying to bring that of gauge field! Thank you

Dear All I am studying Chern Simons theory. Is the non abelian Chern Simons theory the same as topologically massive yang mills theory? Thank yoou

Dear all I am studying Chern simons Theory. If you please can anyone suggest me a book as introduction to Chern Simons theory ( also Chern Simon theory of garuge theories). In fact i will start by a paper of Witten (Quantum Field Theory and the Jones Polynomial)

no i mean gauging conformal group and studying the resulting action if invariant under diffeomorphism group. Do you have any idea about a refernce that could help me in proving this? Thank you

Hello In fact i have studied poincare gauge theory and i deduced that the resulted action is the same as the einstein hilbert one. So currently i am trying to study conformal gauge theory. I am using: E.A.Ivanov and J. Niederle paper Thank you

Dear all I am trying to prove that the action resulting from studying conformal gauge theory is invariant under SO(2,4)*diff. Can anyone give me a hint to start from thank. I considering several papers: E.A.Ivanov and J.Niederie and others...

Thank you i will have a look on Zee's book i have it :) Thank you

sorry for the mistakes too* and are*

Dear Haushofer Sorry for asking to much but your answers is so satisfying. What is the difference between SO(2,3) and SO(1,4)? Thank you

Thank you i got it

Thank you this is so satisfying. Please can you give me a reference for gauging the conformal algebra. I have a one for micho kako

Dear all I just want to ask currently i am studying supergravity. Why it is much important or easier to study the AdS4 supersymmetric de Sitter group and then applying contraction to get superpoincare one than starting directly by gauging superpoincare without any contraction. Thank you

Dear All in the idea of gauging Poincare group i am trying to find the equation of motion of the spin connection w_mu^ab using Euler Lagrange equation. but it seems that i am not getting the same terms can i have a help. I know that this equation is equivalent to the torsionless condition, but...

I will start doing the contraction. In fact i didnt start yet dealing with AdS Backgrounds.

Dear Haushofer In fact i am using notes written by my professor. In addition to P. van Nieuwenhuizen book (Supergravity). I will have a look on Freedman and Van Proyen book Thank you

Hello I took a course on supersymmetry and supergravity in addition to a graduate course on mathematical physics.

No i just want tto know how can i contract from de sitter to poincare

Dear all I am studying formulating supergravity under De Sitter group can anyone suggest me a reference Thank you

Dear All is the torsion always equal zero in supergravity? Thank you

Thank you But the idea I am not able to find eq 20 which is the solution of eq 19

Dear All I am trying to find the equation of motion of the spin connection out of the einstein hilbert action written in terms of the vielbeins. Can anyone help me to do? Thank you

Dear All I have a project about exceptional group as a candidate group for grand unified theories. Can anyone suggest me any paper or reference to use. Thank you

Dear All I am studying spontaneous breaking of supersymmetry but i am confused about something. Why should the goldstone be a spin 1/2, why it is not a boson? I have read that this is due to supersymmetry is a fermionic symmetry but i am not convinced with this answer! Thank you

Dear all Do we have chiral symmetry for weak interaction? I know that weak interaction is chiral. thank you

Dear All I just have a question. We say that the SU(2) doublet have the same value of isospin but the particles of this multiplet differs by I3. Now what quantum number the particles of SU(3) multiplet share. Thank you

Sorry for replying several time but i think i just find the answer in David Bailin and Alexander Love book (1 st edition) page 27. It is noted that if we have Q _alpha ^A; alpha spinor index; while the A labeled some internal symmetry if the Q; A=1...N;. So A labeles the representation of the...

I just want to know the exact meaning of the N, is there is an internal group for the Q's , or should it be related to G. Thank you alot

Thank you haushofer. In fact i was wondering if this number N is related to the internal group G ( We have said that the maximum symmetry of the S matrix is P*G since they commute) which i can later introduce. I thought that this N must be equal to the dimension of G. Thank you haushofer alot.

Dear All Am trying to study supersymmetry algebra. We start by constructing the graded poincare algebra by considering the direct sum of the ordinary Poincare algebra L0 with a subspace L1 spanned by the spinor generators Qa where a runs from 1 to 4 ( L1 is not a lie algebra ). So now we have...

Dear All Can anyone suggest me a book as a basic introduction to supersymmetry In fact i have Wess and West but i need other. Thank you

Dear All I have a project on the topic: " Explaining Why gravity is a non renormalizable theory?". I have downloaded many papers but i need your advice about which paper you think would most benefit me. Thank you

Thank you. In fact it is not so introductory. And i am studying it deeply and in details using Weinberg. I have 1 month to finish it. I just need a good and interesting topic to work on. Thank you for your reply.

Dear All I am currently taking " Introduction to Quantum field theory", And I have to do a project by the end of the course. I have searched and i find : QFT in curved space, QFT for higher spins... But i need other suggestion of topics I can do as a project. Thank you

Hi all I am studying Quantum Field Theory. I read the following statement :"Canonical quantisation is intrinsically not relativistically covariant. Can anyone explain why?. Although everything we did from the beginning was lorentz invariant! Thank you .

Dear all I am studying general relativity and i have a question as follow. We have the 2- sphere can be scanned totally by a coordinate system (theta, phi) with the metric tensor written in terms of theta and phi. Now i want to divide the 2-sphere into charts 4 charts then each will have its own...

Hi all I am studying quantum field theory and i want to just to check something. We have said that the problem with klein gordon equation for real field is that is predict positive and negative energies in addition to the negative probability density. For the complex klein gordon field we have...

Than Thank you for this reply yes for sure it is a typing error :). I just need to check something. If the dimension of the manifold is n then we say that the neighborhood of each point in the manifold is Homeomorphic to an open subset of euclidean space of dimension n ( same dimension). My...

Dear all We all agree that a manifold is globally non euclidean but locally it is. So we can find near each point a hemeomorphic to an open set of euclidean space of the same dimension as the manifold. This is a general definition for all manifold to follow. Then what is the difference between...

Thank You haushofer I will have a look on its content :) Regards,