Modern Physics Letters A

Deep-elastic pp scattering at c.m. energy 14 TeV at LHC in the momentum transfer range 4 GeV² ≲ |t| ≲ 10 GeV² is planned to be measured by the TOTEM group. We study this process in a model where the deep-elastic scattering is due to a single hard collision of a valence quark from one proton with a valence quark from the other proton. The hard collision originates from the low-x gluon cloud around one valence quark interacting with that of the other. The low-x gluon cloud can be identified as color glass condensate and has size ≃0.3 F. Our prediction is that pp dσ/dt in the large |t| region decreases smoothly as momentum transfer increases. This is in contrast to the prediction of pp dσ/dt with visible oscillations and smaller cross sections by a large number of other models.

In lattice Schrödinger picture, the wave functionals of the squeezed vacuum states of a free real scalar field in de Sitter space are constructed explicitly in momentum space by using the method of instantaneous Hamiltonian diagonalization. The modified power spectrum and particle production in the general mixed, squeezed initial states are also presented. For the massless minimally coupled scalar field which is relevant to slow roll inflationary models, we recover the power spectrum of scalar fluctuations for the squeezed vacuum states, and show that the evolution of the squeezed vacuum states exhibits an attractor behavior. The case of a massless conformally coupled scalar field is also discussed.

From the fractal properties of the hadron suggested by the statistical model, the colour factor ratio $\genfrac{}{}{0.1ex}{}{C_A}{C_F}$ has been derived and is found to be in exact agreement with the corresponding QCD prediction.

We investigate a flat anisotropic (5+1)-dimensional cosmological model in the presence of the Gauss–Bonnet (GB) contribution in addition to the usual Einstein term in the action. We compared it with (4+1)-dimensional case and found a substantial difference in the corresponding cosmological dynamics. This difference is manifested in the probability of the model to have smooth transition from GB-term-dominated to Einstein-term-dominated phases — this probability in a reasonable measure on the initial condition space is almost zero for (4+1) case and about 60% for (5+1) case. We discuss this difference as well as some features of the dynamics of the considered model.

We study the effect of neutrino flux regeneration by neutral current on the Standard Model prediction for the recently proposed observable angular α_SM(E). This observable has a weak dependence with the initial flux through the regeneration term in the transport equation. We want to know the impact of the initial flux uncertainties on the mentioned observable.

The purpose of the present study is to show that in a particular cosmological model, with an affine equation of state, one can obtain, besides the background given by the scale factor, Hubble and deceleration parameters, a representation in terms of scalar fields and, more important, explicit mathematical expressions for the density contrast and the power spectrum. Although the model so obtained is not realistic, it reproduces features observed in some previous numerical studies, and as such it indicates that the Chaplygin gas by itself is not competitive when compared to the usual Λ-CDM model.

Hybrid Chaplygin gas model is put forward, in which the gases play the role of dark energy. For this model the coincidence problem is greatly alleviated. The effective equation of state of the dark energy may cross the phantom divide w = -1. Furthermore, the crossing behavior is decoupled from any gravity theories. In the present model, w < -1 is only a transient behavior. There is a de Sitter attractor in the future infinity. Hence, the big rip singularity, which often afflicts the models with matter whose effective equation of state less than -1, naturally disappears. There exist stable scaling solutions, both at the early universe and the late universe. We discuss the perturbation growth of this model. We find that the index is consistent with observations.