## MH 1020

Yielding naturally values in the TeV range. The gauge group closest to the Standard Model one can easily obtain with D-branes is U(3) x U(2) x U(1). The first factor arises from three coincident color D-branes. An open string with one end on them is a triplet under SU(3) and carries the same U(1) charge for all three components. Thus, the U(1) factor of U(3) has to be identified with gauged baryon number. Similarly, U(2) arises from two coincident weak D-branes and the corresponding abelian...

## References

Notes Phys. 653, 141 (2004). 189 2. S. Weinberg, Rev. Mod. Phys. 61, 1 (1989). 189 3. S.M. Carroll, W.H. Press and E.L. Turner, Ann. Rev. Astron. Astrophys. 30, 499 (1992). 189 4. N. Straumann, arXiv astro-ph 0203330. 189 5. P.J.E. Peebles and B. Ratra, Astrophys. J. 325, L17 (1988). 257 6. R.R. Caldwell, R. Dave and P.J. Steinhardt, Phys. Rev. Lett. 80, 1582 (1998). 191 7. S.M. Carroll, Phys. Rev. Lett. 81, 3067 (1998). 191 8. P.J. Steinhardt, Quintessence and Cosmic...

## Info

Hence H diverges for t ts. This is so-called the Big Rip singularity at which the Hubble rate and the energy density Table 8.2. The properties of the critical points (s saddle, p point, n node, st stable) for e 1 (from 3 ) Table 8.2. The properties of the critical points (s saddle, p point, n node, st stable) for e 1 (from 3 )

## ST1 dSL

The first term corresponds to the usual homogeneous redshifting of photons and the second, integrated over the whole photon path, gives the term in Sachs-Wolfe expression (see below). Here and below, the dots represent derivatives with respect to conformal time t . In synchronous gauge, these various effects are combined to give -51 + vr n - - J hijiiiiijdT , (7.15) where the dots are derivatives with respect to co-moving time and n is a unit vector along the line of sight. This is known as the...

## Tgh 1210

And the entropy, associated with the de Sitter horizon of area A, is given exactly by the formula (12.8). These properties can be proven by considering a quantum field on the dS background and evaluating its Green functions. Such an analysis shows that, in the case of massive quantum fields, an observer, moving along a time-like geodesic of dS space, observes a thermal bath of particles, when the massive field is in its vacuum state 0 > . It turns out that the correct type of Green functions...

## H gm Q pm p

3 + +1 + em 3pm) (12'76) where pm and pm denote the matter energy density and pressure respectively including dark matter contributions. As usual, the overdot denotes derivatives with respect to the Einstein time, and H is the Hubble parameter of the Robertson-Walker Universe. The r.h.s of the above equations denotes the non-critical string off-shell terms appearing in (12.46), due to the non-equilibrium nature of the pertinent cosmology. The latter could be due to an initial cos-mically...

## The Thermal Universe

At early times the ingredients of our Universe were the Standard Model particles, and perhaps additional as yet undiscovered particle species, being in a state of hot plasma in thermodynamic and chemical equilibrium. At a given temperature T the energy density of a particular particle species of mass m is given by The functions g(T) can not be expressed in a closed form. However for temperatures, kT > > m, the particle is almost relativistic and g(T) is just a constant given by The...

## On the Direct Detection of Dark Matter

Physics Department, University of Ioannina, Gr 451 10, Ioannina, Greece vergados cc.uoi.gr Abstract. Various issues related to the direct detection of supersymmetric dark matter are reviewed. Such are 1) Construction of supersymmetric models with a number of parameters, which are constrained from the data at low energies as well as cosmological observations. 2) A model for the nucleon, in particular the dependence on the nucleon cross section on quarks other than u and d. 3) A nuclear model,...

## Kk

The empty wave function (14.81) is obviously normalizable, so it gives a state of the quantum system. We can build a complete set of normalized stationary states by acting arbitrary numbers of + and raising operators on it, On this space of states the Hamiltonian operator is unbounded below, just as in the classical theory, H N+,N_) (N+ k+ N_k_j N+ ,N_) . (14.83) This is the correct way to quantize a higher derivative theory. One evidence of this fact is that classical negative energy states...