相关论文: Concatenation of Scales Below 1 eV
A short review about vacuum energy and the cosmological constant is presented. The observed acceleration of the universe introduces a new meV energy scale. The problem is that, theoretically, the predicted vacuum energy is many orders of…
The observed interaction energy of cosmic rays with atmospheric nuclei reaches up to a PeV in the center of mass. We compute nucleon-nucleon and nucleon-neutrino cross sections for various generic parton cross sections appearing in string…
The gauge coupling constant unification at the low ($O$(TeV)) scale can be obtained just in four dimensions, without help of the power like renormalization group evolution in extra dimensions, due to the presence of some extra particle…
If the minimal standard model of particle interactions is extended to include a scalar triplet with lepton number $L=-2$ and a scalar doublet with $L=-1$, neutrino masses $m_\nu \sim \mu_{12}^4 v^2/M^5 \sim 10^{-2}$ eV is possible, where $v…
Arkani-Hamed, Dimopoulos, and Dvali have proposed that the fundamental gravitational scale is close to 1 TeV, and that the observed weakness of gravity at long distances is explained by the presence of large extra compact dimensions. If…
Physics beyond the standard model might imply the cosmological production of particles with grand unification scale energies. Nucleons and gamma-rays from such processes are candidates for the cosmic rays observed beyond 100 EeV [10**(20)…
The possible existence of bulk singlet neutrinos in the scenario with large compactified dimensions and low string scale $M_*$ has important consequences for low-energy observables. We demonstrate that intergenerational mass splitting and…
Five fundamental scales of mass follow from holographic limitations, a self-similar law for angular momentum and the basic scaling laws for a fractal universe with dimension 2. The five scales correspond to the observable universe,…
We discuss the validity of general relativity at low-energy and relate the threshold below which the theory breaks down with the observed value of the cosmological constant. This suggests the existence of a mass scale of ${\cal O}(10^{-3})…
A class of grand unified theories with symmetry breaking scale of order $10^{16} GeV$ have a Higgs particle with mass in the $TeV$ scale. The cosmology of such theories is very different from usual. We study the cosmic strings obtained in…
Recently, a number of authors have challenged the conventional assumption that the string scale, Planck mass, and unification scale are roughly comparable. It has been suggested that the string scale could be as low as a TeV. In this note,…
We present an argument in which the scale ~ 0.1 eV associated with neutrino masses naturally appears in a a class of (very) large volume compactifications, being tied to a supersymmetry scale of 10^3 GeV and a string scale of 10^11 GeV. The…
Among three typical energy scales, a neutrino mass scale ($m_\nu\sim$ 0.1 eV), a GUT scale ($M_{GUT}\sim 10^{16}$ GeV), and a TeV-scale ($M_{NP}\sim 1$ TeV), there is a fascinating relation of $M_{NP}\simeq \sqrt{m_\nu\cdot M_{GUT}}$. The…
I briefly review cosmological bounds on neutrino masses and the underlying gravitational physics at a level appropriate for readers outside the field of cosmology. For the case of three massive neutrinos with standard model freezeout, the…
A new mechanism for understanding small neutrino masses using only simple new physics at the TeV scale is proposed. As an application, it is shown how it can naturally lead to the mass hierarchy of the so called bimaximal mixing in the case…
The recently proposed model of neutrino mass with no new physics beyond the TeV energy scale is shown to admit a natural and realistic supersymmetric realization, when combined with another recently proposed model of quark masses in the…
Upper limits on neutrino masses from cosmology have been reported recently to reach the impressive sub-eV level, which is competitive with future terrestrial neutrino experiments. In this brief review of the latest limits from cosmology we…
While it is established that the effect of neutrinos on the evolution of cosmic structure is small, the upper limits derived from large-scale structure could help significantly to constrain the absolute scale of the neutrino masses. Current…
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m_nu undetermined. The most restrictive limit of m_nu < 0.8 eV arises…
We live in a four dimensional world. But the idea of unification of fundamental interactions lead us to higher dimensional theories. Recently a new theory with extra dimensions has emerged, where only gravity propagates in the extra…