We generalize the usual octet, decuplet and exotic antidecuplet and higher baryon multiplets to any number of colours Nc. We show that the multiplets fall into a sequence of bands with O(1/Nc) splittings inside the band and O(1) splittings between the bands characterized by “exoticness”, that is the number of extra quark-antiquark pairs needed to compose the multiplet. Each time one adds a pair...

The masses of the flavor octet and singlet baryons with negative parity and spin 1 2 are calculated using the QCD sum rule. We find that the chiral symmetry breaking vacuum condensates cause the mass splitting of the positive and negative baryons. The present sum rule reproduces the observed masses of these baryons within 10%, and predicts the mass of the excited Ξ baryon with J P = 1 2 − at 1....

We present a complete computation of the inflaton decay into very massive fermions during preheating, including back-reaction effects. We show that heavy fermions are produced very efficiently up to masses of order 10–10 GeV; the accessible mass range is thus even broader than the one for heavy bosons. We apply our findings to the leptogenesis scenario, proposing a new version of it, in which t...

Leptogenesis constitues a very simple scenario to achieve the baryon asymmetry that we observe today. It requires only the presence of right handed neutrinos (which arise very naturally in many extensions of the Standard Model) and depends crucially on the mechanism responsible for their production. In particular, when their mass exceeds the inflaton mass (10 13 GeV in chaotic inflation) only n...

Preliminary results for the light baryon spectrum computed in an on-going QCD simulation using 2+1 flavors of domain wall fermions and the Iwasaki gauge action are presented and discussed. Lattice sizes 243×64 and 323×64 with spacings 0.114 and∼ 0.08 fm are used in the calculation. The physical spatial size is thus 2.74 fm and ∼ 2.6 fm, respectively. The degenerate light quarks have masses down...

The least well-known octet baryon mass is MΞ0 = 1314.9 ± 0.6 MeV. The prospect of an improved measurement of its mass by the KTeV experimental program at Fermilab, and opportunities for improvements in charged and excited hyperon and ∆ mass measurements, makes it timely to re-examine descriptions of isospin splittings in baryons containing light quarks. By examining such relations as the Colema...

We study big bang nucleosynthesis in the presence of large mass-scale, non-linear entropy fluctuations. Overdense regions, with masses above the local baryon-Jeans mass, are expected to collapse and form condensed objects. Surviving nucleosynthesis products therefore tend to originate from underdense regions. We compute expected surviving light element (H, He, He, Li) abundance yields for a var...

The masses of the flavor octet and singlet baryons with negative parity and spin 1 2 are calculated using the QCD sum rule. We find that the chiral symmetry breaking vacuum condensates cause the mass splitting of the positive and negative baryons. The present sum rule reproduces the observed masses of these baryons within 10%, and predicts the mass of the excited Ξ baryon with J P = 1 2 − at 1....

Analytical representations are derived for two equations of state (EOSs) of neutron-star matter: FPS and SLy. Each of these EOSs is unified, that is, it describes the crust and the core of a neutron star using the same physical model. Two versions of the EOS parametrization are considered. In the first one, pressure and mass density are given as functions of the baryon density. In the second ve...

Using 4 flavors of staggered fermions at infinite gauge coupling, we compare various analytic results for the hadron spectrum with exact Monte Carlo simulations. Agreement with Ref. [4] is very good, at the level of a few percent. Our results give credence to a discrepancy between the baryon mass and the critical chemical potential, for which baryons fill the lattice at zero temperature and inf...