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[en] The scattering of scalar waves from a Schwarzschild black hole is investigated for wavelengths much less than the graviational radius (r/sub s/). Explicit expressions for scattering parameters are obtained for two cases: high angular momenta and low angular momenta. In the first case we obtain the phase shifts and absorption coefficient with the JWKB method. The elastic differential cross section and the total absorption cross section are also calculated. For low angular momenta we present a method based in the DWBA (distorted wave Born approximation). With this method, the phase shifts and the absorption coefficients are obtained
[en] The cosmic microwave background power spectra are studied for different families of single field new and chaotic inflation models in the effective field theory approach to inflation. We implement a systematic expansion in 1/Ne, where Ne∼50 is the number of e-folds before the end of inflation. We study the dependence of the observables (ns, r and dns/d ln k) on the degree of the potential (2n) and confront them to the WMAP3 and large scale structure data: This shows in general that fourth degree potentials (n=2) provide the best fit to the data; the window of consistency with the WMAP3 and LSS data narrows for growing n. New inflation yields a good fit to the r and ns data in a wide range of field and parameter space. Small field inflation yields r < 0.16 while large field inflation yields r > 0.16 (for Ne=50). All members of the new inflation family predict a small but negative running -4(n+1) x 10-4 (le) dns/d ln k (le) -2 x 10-4. (The values of r, ns, dns/d ln k for arbitrary Ne follow by a simple rescaling from the Ne=50 values.) A reconstruction program is carried out suggesting quite generally that for ns consistent with the WMAP3 and LSS data and r < 0.1 the symmetry breaking scale for new inflation is |φ0|∼10 MPl while the field scale at Hubble crossing is |φc| ∼ MPl. The family of chaotic models features r (ge) 0.16 (for Ne=50) and only a restricted subset of chaotic models are consistent with the combined WMAP3 bounds on r, ns, dns/d ln k with a narrow window in field amplitude around |φc|∼15 MPl. We conclude that a measurement of r < 0.16 (for Ne=50) distinctly rules out a large class of chaotic scenarios and favors small field new inflationary models. As a general consequence, new inflation emerges more favored than chaotic inflation
[en] In TeV scale unification models, gravity propagates in 4+δ dimensions while gauge and matter fields are confined to a four dimensional brane, with gravity becoming strong at the TeV scale. For a such scenario, we study strong gravitational interactions in a effective Schwarzschild geometry. Two distinct regimes appear. For large impact parameters, the ratio ρ∼(Rs/r0)1+δ (with Rs the Schwarzschild radius and r0 the closest approach to the black hole), is small and the deflection angle χ is proportional to ρ (this is like Rutherford-type scattering). For small impact parameters, the deflection angle χ develops a logarithmic singularity and becomes infinite for ρ=ρcrit=2/(3+δ). This singularity is reflected into a strong enhancement of the backward scattering (like a glory-type effect). We suggest as distinctive signature of black hole formation in particle collisions at TeV energies, the observation of backward scattering events and their associated diffractive effects
[en] The Thomas-Fermi approach to galaxy structure determines self-consistently and non-linearly the gravitational potential of the fermionic warm dark matter (WDM) particles given their quantum distribution function f(E). This semiclassical framework accounts for the quantum nature and high number of DM particles, properly describing gravitational bounded and quantum macroscopic systems as neutron stars, white dwarfs and WDM galaxies. We express the main galaxy magnitudes as the halo radius r_h, mass M_h, velocity dispersion and phase space density in terms of the surface density which is important to confront to observations. From these expressions we derive the general equation of state for galaxies, i.e., the relation between pressure and density, and provide its analytic expression. Two regimes clearly show up: (1) Large diluted galaxies for M_h >or similar 2.3 x 10"6 M _C_i_r_c_l_e_D_o_t and effective temperatures T_0 > 0.017 K described by the classical self-gravitating WDM Boltzman gas with a space-dependent perfect gas equation of state, and (2) Compact dwarf galaxies for 1.6 x 10"6 M _C_i_r_c_l_e_D_o_t >or similar M_h >or similar M_h_,_m_i_n ≅ 3.10 x 10"4 (2 keV/m)"("1"6")"/"("5") M _C_i_r_c_l_e_D_o_t, T_0 < 0.011 K described by the quantum fermionic WDM regime with a steeper equation of state close to the degenerate state. In particular, the T_0 = 0 degenerate or extreme quantum limit yields the most compact and smallest galaxy. In the diluted regime, the halo radius r_h, the squared velocity v"2(r_h) and the temperature T_0 turn to exhibit square-root of M_h scaling laws. The normalized density profiles ρ(r)/ρ(0) and the normalized velocity profiles v"2(r)/v"2(0) are universal functions of r/r_h reflecting the WDM perfect gas behavior in this regime. These theoretical results contrasted to robust and independent sets of galaxy data remarkably reproduce the observations. For the small galaxies, 10"6 >or similar M_h ≥ M_h_,_m_i_n, the equation of state is galaxy mass dependent and the density and velocity profiles are not anymore universal, accounting to the quantum physics of the self-gravitating WDM fermions in the compact regime (near, but not at, the degenerate state). It would be extremely interesting to dispose of dwarf galaxy observations which could check these quantum effects. (orig.) 1
[en] We provide a unified formula for the quantum decay rate of heavy objects (particles) whatever they may be: topological and nontopological solitons, X particles, cosmic defects, microscopic black holes, fundamental strings, as well as the particle decays in the standard model. Extreme energy cosmic ray (EECR) top-down scenarios are based on relics from the early Universe. The key point in the top-down scenarios is the necessity to adjust the lifetime of the heavy object to the age of the Universe. This ad hoc requirement needs a very high dimensional operator to govern its decay and/or an extremely small coupling constant. The arguments produced to fine-tune the relic lifetime to the age of the Universe are critically analyzed. The natural lifetimes of such heavy objects are, however, microscopic times associated with the grand unified theory energy scale (∼10-28 sec or shorter). It is at this energy scale (by the end of inflation) that they could have been abundantly formed in the early Universe, and it seems natural that they decayed shortly after being formed. The annihilation scenario for EECRs ('wimpzillas') is also considered and its inconsistencies analyzed
[en] Recently, Warm (keV scale) Dark Matter emerged impressively over CDM (Cold Dark Matter) as the leading Dark Matter candidate. In the context of this new Dark Matter situation, which implies novelties in the astrophysical, cosmological and keV particle physics context, this 16. Paris Colloquium 2012 is devoted to the LambdaWDM Standard Model of the Universe. The topics of the colloquium are as follows: -) observational and theoretical progress on the nature of dark matter: keV scale warm dark matter, -) large and small scale structure formation in agreement with observations at large scales and small galactic scales, and -) neutrinos in astrophysics and cosmology. This document gathers the slides of the presentations.
[en] We develop the cluster expansion and the Mayer expansion for the self-gravitating thermal gas and prove the existence and stability of the thermodynamic limit N,V→∞ with N/V13 fixed. The essential (dimensionless) variable is here η=Gm2N(V13T) (which is kept fixed in the thermodynamic limit). We succeed in this way to obtain the expansion of the grand canonical partition function in powers of the fugacity. The corresponding cluster coefficients behave in the thermodynamic limit as (ηN)j-1cj, where cj are pure numbers. They are expressed as integrals associated to tree cluster diagrams. A bilinear recurrence relation for the coefficients cj is obtained from the mean field equations in the Abel's form. In this way the large j behaviour of the cj is calculated. This large j behaviour provides the position of the nearest singularity which corresponds to the critical point (collapse) of the self-gravitating gas in the grand canonical ensemble. Finally, we discuss why other attempts to define a thermodynamic limit for the self-gravitating gas fail
[en] We clarify inflaton models by considering them as effective field theories in the Ginzburg-Landau spirit. In this new approach, the precise form of the inflationary potential is constructed from the present WMAP data, and a useful scheme is prepared to confront with the forthcoming data. In this approach, the WMAP statement excluding the pure φ4 potential implies the presence of an inflaton mass term at the scale m∼1013 GeV. Chaotic, new and hybrid inflation models are studied in an unified way. In all cases the inflaton potential takes the form V(φ)=m2MPl2v(φ/MPl), where all coefficients in the polynomial v(φ) are of order one. If such potential corresponds to supersymmetry breaking, the corresponding susy breaking scale is √(mMPl)∼1016 GeV which turns to coincide with the grand unification (GUT) scale. The inflaton mass is therefore given by a seesaw formula m∼MGUT2/MPl. The observables turn to be two-valued functions: one branch corresponds to new inflation and the other to chaotic inflation, the branch point being the pure quadratic potential. For red tilted spectrum, the potential which fits the best the present data (vertical bar 1-ns vertical bar < or approx. 0.1,r < or approx. 0.1) and which best prepares the way for the forthcoming data is a trinomial polynomial with negative quadratic term (new inflation). For blue tilted spectrum, hybrid inflation turns to be the best choice. In both cases we find an analytic formula relating the inflaton mass with the ratio r of tensor to scalar perturbations and the spectral index ns of scalar perturbations: 106(m/MPl)=127√(r vertical bar 1-ns vertical bar) where the numerical coefficient is fixed by the WMAP amplitude of adiabatic perturbations. Implications for string theory are discussed
[en] Research highlights: → In Ginsburg-Landau (G-L) approach data favors new inflation over chaotic inflation. → ns and r fall inside a universal banana-shaped region in G-L new inflation. → The banana region for the observed value ns=0.964 implies 0.021< r<0.053. → Fermion condensate inflaton potential is a double well in the G-L class. - Abstract: The MCMC analysis of the CMB + LSS data in the context of the Ginsburg-Landau approach to inflation indicated that the fourth degree double-well inflaton potential in new inflation gives an excellent fit of the present CMB and LSS data. This provided a lower bound for the ratio r of the tensor to scalar fluctuations and as most probable value r ≅ 0.05, within reach of the forthcoming CMB observations. In this paper we systematically analyze the effects of arbitrarily higher order terms in the inflaton potential on the CMB observables: spectral index ns and ratio r. Furthermore, we compute in close form the inflaton potential dynamically generated when the inflaton field is a fermion condensate in the inflationary universe. This inflaton potential turns out to belong to the Ginsburg-Landau class too. The theoretical values in the (ns, r) plane for all double well inflaton potentials in the Ginsburg-Landau approach (including the potential generated by fermions) fall inside a universal banana-shaped region B. The upper border of the banana-shaped region B is given by the fourth order double-well potential and provides an upper bound for the ratio r. The lower border of B is defined by the quadratic plus an infinite barrier inflaton potential and provides a lower bound for the ratio r. For example, the current best value of the spectral index ns = 0.964, implies r is in the interval: 0.021 < r < 0.053. Interestingly enough, this range is within reach of forthcoming CMB observations.
[en] We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the dynamics of the (classical) cosmological metric. For chaotic inflation, the quantum treatment avoids the unnatural requirements of an initial state with all the energy in the zero mode. For new inflation it allows a consistent treatment of the explosive particle production due to spinodal instabilities. Quantum field inflation (under conditions that are the quantum analog of slow-roll) leads, upon evolution, to the formation of a condensate starting a regime of effective classical inflation. We compute the primordial perturbations taking the dominant quantum effects into account. The results for the scalar, vector and tensor primordial perturbations are expressed in terms of the classical inflation results. For a N-component field in a O(N) symmetric model, adiabatic fluctuations dominate while isocurvature or entropy fluctuations are negligible. The results agree with the current Wilkinson Microwave Anisotropy Probe observations and predict corrections to the power spectrum in classical inflation. Such corrections are estimated to be of the order of (m2/NH2), where m is the inflaton mass and H the Hubble constant at the moment of horizon crossing. An upper estimate turns to be about 4% for the cosmologically relevant scales. This quantum field treatment of inflation provides the foundations to the classical inflation and permits to compute quantum corrections to it