For the closed string carrying 2 or 3 point-like masses the stability problem for central and linear rotational states is considered. This problem is important for applications of these model to describing baryons, glueballs or other exotic hadrons. The linear rotational state correspond to an uniform rotation of the system with rectilinear string segments, connecting massive points. The state is named ``central'' one, if there is a massive point at the rotational center. It is shown that the linear rotational states with 2 massive points are stable with respect to small disturbances. But the central rotational states with 3 masses are not stable, if the central mass it less than energy of the string with other massive points. This effect may change properties of excited hadron states, in particular, increase their width.
In the context of the bosonic string theory, we shall extract the general radiation amplitude of a massless closed string from the interaction of two parallel unstable D$p$-branes. The branes are non-stationary and have been dressed by background fields. The foregoing amplitude will be rewritten for the massless state radiation from the branes with the large distance. Besides, we shall study the gravitational and dilatonic radiations from this configuration.
We calculate the spectral distortions from Hawking evaporation of primordial black holes before the epoch of recombination, taking into account emission of all standard model particles, including quark and gluons, and evolving the resulting particle cascades in the expanding Universe. We show that the constraints on the abundance of primordial black holes are stronger by more than an order of magnitude compared to the previous calculations which take only the primary photon emission into account. We also show that the shapes of the spectral distortions is different from the $y$ or $i$-type dis…
A Chromomagnetic Mechanism for the Rotational Phase Transition of Gluonic Matter
Institute for Astrophysics, School of Physics, Zhengzhou University（郑州大学物理学院天体物理研究所）；School of Physics, Hangzhou Normal University（杭州师范大学物理学院）；School of Nuclear Science and Technology, University of Chinese Academy of Sciences（中国科学院大学核科学与技术学院）
Unstable heavy particles well above the TeV scale are unaccessible experimentally. So far, Big-Bang Nucleosynthesis (BBN) provides the strongest limits on their mass and lifetime, the latter being shorter than 0.1 second. We show how these constraints could be potentially tremendously improved by the next generation of Gravitational-Wave (GW) interferometers, extending to lifetimes as short as $10^{-16}$ second. The key point is that these particles may have dominated the energy density of the universe and have triggered a period of matter domination at early times, until their decay before BB…
An approximate rotational symmetry of a heavy-light meson is viewed from a string picture. Using a simple string configuration, we derive a formula, $(M-m_c)^2=πσL$, whose coefficient of the r.h.s. is just 1/2 of that of a light meson with two light quarks. A numerical plot is obtained for $D$ mesons of experimental data as well as several theoretical models, which shows good agreement with this formula.
