Zhen-Yun Fang

Impulsive cylindrical gravitational wave: one possible radiative form emitted from cosmic strings and corresponding electromagnetic response

The cosmic strings (CSs) may be one type of important source of gravitational waves (GWs), and it has been intensively studied due to its special properties such as the cylindrical symmetry. The CSs would generate not only usual continuous GWs, but also impulsive GWs that bring about a more concentrated energy and consist of different GW components, broadly covering low-, intermediate- and high-frequency bands simultaneously. These features might underlie interesting electromagnetic (EM) responses to these GWs generated by the CSs. In this paper, with novel results and effects, we firstly calculate the analytical solutions of perturbed EM fields caused by the interaction between impulsive cylindrical GWs (which would be one of possible forms emitted from CSs) and background celestial high magnetic fields or widespread cosmological background magnetic fields, by using the exact form of the Einstein–Rosen metric rather than the planar approximation usually applied. The results show that perturbed EM fields are also in the impulsive form in accordant to the GW pulse, and the asymptotic behaviors of the perturbed EM fields are fully consistent with the asymptotic behaviors of the energy density, energy flux density, and Riemann curvature tensor of the corresponding impulsive cylindrical GWs. The analytical solutions naturally give rise to the accumulation effect (due to the synchro-propagation of perturbed EM fields and the GW pulse, because of their identical propagating velocities, i.e., the speed of light), which is proportional to the

\Xi_{bc}

\sqrt\mathrm{distance}

Quasi-B-mode generated by high-frequency gravitational waves and corresponding perturbative photon fluxes

distance. Based on this accumulation effect, in consideration of very widely existing background galactic–extragalactic magnetic fields in all galaxies and galaxy clusters, we for the first time predict potentially observable effects in the region of the Earth caused by the EM response to GWs from the CSs.

Doubly Heavy Baryon Production at A High Luminosity

We investigate the hadronic production of the doubly heavy baryon {Xi}{sub bc} at the Large Hadron Collider (LHC), where contributions from the four (bc)-diquark states (bc){sub 3,6}[{sup 1}S{sub 0}] and (bc){sub 3,6}[{sup 3}S{sub 1}] have been taken into consideration. Numerical results show that under the condition of p{sub T}>4 GeV and |y|<1.5, sizable {Xi}{sub bc} events about 1.7x10{sup 7} and 3.5x10{sup 9} per year can be produced for the center-of-mass energy {radical}(S)=7 TeV and {radical}(S)=14 TeV, respectively. For experimental usage, the total and the interested differential cross sections are estimated under some typical p{sub T} and y cuts for the LHC detectors CMS, ATLAS, and LHCb. The main uncertainties are discussed and a comparative study on the hadronic production of {Xi}{sub cc}, {Xi}{sub bc}, and {Xi}{sub bb} at the LHC are also presented.

e^+ e^-

Abstract Interaction of very low-frequency primordial (relic) gravitational waves (GWs) to cosmic microwave background (CMB) can generate B-mode polarization. Here, for the first time we point out that the electromagnetic (EM) response to high-frequency GWs (HFGWs) would produce quasi-B-mode distribution of the perturbative photon fluxes. We study the duality and high complementarity between such two B-modes, and it is shown that such two effects are from the same physical origin: the tensor perturbation of the GWs and not the density perturbation. Based on this quasi-B-mode in HFGWs and related numerical calculation, it is shown that the distinguishing and observing of HFGWs from the braneworld would be quite possible due to their large amplitude, higher frequency and very different physical behaviors between the perturbative photon fluxes and background photons, and the measurement of relic HFGWs may also be possible though face to enormous challenge.

Collider

Within the framework of nonrelativistic QCD, we make a detailed discussion on the doubly heavy baryon production through the

New results on Pionic Twist-3 Distribution Amplitudes within the QCD Sum Rules

e^+ e^-

Hadronic decays of the spin-singlet heavy quarkomium under the principle of maximum conformality ∗

annihilation channel,