Production of heavy isotopes in transfer reactions by collisions of 238^{238}U+238^{238}U

The dynamics of transfer reactions in collisions of two very heavy nuclei $^{238}$U+$^{238}$U is studied within the dinuclear system (DNS) model. Collisions of two actinide nuclei form a super heavy composite system during a very short time, in which a large number of charge and mass transfers may take place. Such reactions have been investigated experimentally as an alternative way for the production of heavy and superheavy nuclei. The role of collision orientation in the production cross sections of heavy nuclides is analyzed systematically. Calculations show that the cross sections decrease drastically with increasing the charged numbers of heavy fragments. The transfer mechanism is favorable to synthesize heavy neutron-rich isotopes, such as nuclei around the subclosure at N=162 from No (Z=102) to Db (Z=105).Comment: 4 pages, 4 figure

QCD and Relativistic O(αsv2)O(\alpha_{s}v^2) Corrections to Hadronic Decays of Spin-Singlet Heavy Quarkonia hc,hbh_c, h_b and ηb\eta_b

We calculate the annihilation decay widths of spin-singlet heavy quarkonia $h_c, h_b$ and $\eta_b$} into light hadrons with both QCD and relativistic corrections at order $O(\alpha_{s}v^{2})$ in nonrelativistic QCD. With appropriate estimates for the long-distance matrix elements by using the potential model and operator evolution method, we find that our predictions of these decay widths are consistent with recent experimental measurements. We also find that the $O(\alpha_{s}v^{2})$ corrections are small for $b\bar{b}$ states but substantial for $c\bar{c}$ states. In particular, the negative contribution of $O(\alpha_{s}v^{2})$ correction to the $h_{c}$ decay can lower the decay width, as compared with previous predictions without the $O(\alpha_{s}v^{2})$ correction, and thus result in a good agreement with the recent BESIII measurement.Comment: version published in PRD, 30 pages, 8 figures, more discussions on LDMEs adde

Elastic parton scattering and non-statistical event-by-event mean-pt fluctuations in Au + Au collisions at RHIC

Non-statistical event-by-event mean-pt fluctuations in Au + Au collisions at sqrt(s_NN) = 130 and 200 GeV are analyzed in AMPT with string-melting, and the results are compared with STAR data. The analysis suggests that in-medium elastic parton scattering may contribute greatly to the mean-p_t fluctuations in relativistic heavy-ion collisions. Furthermore, it is demonstrated that non-statistical event-by-event mean-pt fluctuations can be used to probe the initial partonic dynamics in these collisions. The comparison shows that with an in-medium elastic parton scattering cross section sigma_p=10 mb, AMPT with string-melting can well reproduce sqrt(s_NN) = 130 GeV data on the centrality dependence of non-statistical event-by-event mean-pt fluctuations. The comparison also shows that the fluctuation data for sqrt(s_NN) = 200 GeV Au + Au collisions can be well reproduced with sigma_p between 6 and 10 mb.Comment: 6 pages, 3 figure

Formation of superheavy nuclei in cold fusion reactions

Within the concept of the dinuclear system (DNS), a dynamical model is proposed for describing the formation of superheavy nuclei in complete fusion reactions by incorporating the coupling of the relative motion to the nucleon transfer process. The capture of two heavy colliding nuclei, the formation of the compound nucleus and the de-excitation process are calculated by using an empirical coupled channel model, solving a master equation numerically and applying statistical theory, respectively. Evaporation residue excitation functions in cold fusion reactions are investigated systematically and compared with available experimental data. Maximal production cross sections of superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles are obtained. Isotopic trends in the production of the superheavy elements Z=110, 112, 114, 116, 118 and 120 are analyzed systematically. Optimal combinations and the corresponding excitation energies are proposed.Comment: 18 pages, 8 figure

Probing for the Cosmological Parameters with PLANCK Measurement

We investigate the constraints on cosmological parameters especially for EoS of dark energy, inflationary parameters, neutrino mass and curvature of universe using simulated Planck data. Firstly we determine cosmological parameters with current observations including ESSENCE, WMAP3, Boomerang-2K2, CBI, VSA, ACBAR, SDSS LRG and 2dFGRS, and take best-fit model as the fiducial model in simulations. In simulations we pay attention to the effects of dynamical dark energy in determination of cosmological parameters. We add simulated SNAP data to do all the simulations. Using present data, we find Quintom dark energy model is mildly favored while \LambdaCDM remains a good fit. In the framework of dynamical dark energy, the constraints on inflationary parameters, m_{\nu} and \Omega_{K} become weak compared with the constraints in \LambdaCDM. Intriguingly, we find that the inflationary models with a "blue" tilt, which are excluded about 2\sigma in \LambdaCDM model, are well within 2\sigma region with the presence of the dynamics of dark energy. The upper limits of neutrino mass are weakened by a factor of 2 (95% C.L.), say, m_{\nu}<1.59 eV and m_{\nu}<1.53 eV for two forms of parametrization of the equation of state of dark energy. The flat universe is a good fit to the current data, namely, |\Omega_{K}|<0.03 (95% C.L.). With the simulated Planck and SNAP data, dynamical dark energy and \LambdaCDM might be distinguished at 4\sigma. And uncertainties of inflationary parameters, m_{\nu} and \Omega_{K} can be reduced obviously. We also constrain the rotation angle \Delta\alpha, denoting possible cosmological CPT violation, with simulated Planck and CMBpol data and find that our results are much more stringent than current constraint and will verify cosmological CPT symmetry with a higher precision. (Abridged)Comment: 15 pages, 8 figures and 3 tables, Accepted for publication in Int.J.Mod.Phys.

Determining Cosmological Parameters with Latest Observational Data

In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation (307 sample) to determine the cosmological parameters. Our results show that the $\Lambda$CDM model remains a good fit to the current data. In a flat universe, we obtain the tight limit on the constant EoS of dark energy as, $w=-0.977\pm0.056$ ($1 \sigma$). For the dynamical dark energy models with time evolving EoS, we find that the best-fit values are $w_0=-1.08$ and $w_1=0.368$, implying the preference of Quintom model whose EoS gets across the cosmological constant boundary. For the curvature of universe, our results give $-0.012<\Omega_k<0.009$ (95% C.L.) when fixing w_{\DE}=-1. When considering the dynamics of dark energy, the flat universe is still a good fit to the current data. Regarding the neutrino mass limit, we obtain the upper limits, $\sum m_{\nu}<0.533$ eV (95% C.L.) within the framework of the flat $\Lambda$CDM model. When adding the SDSS Lyman-$\alpha$ forest power spectrum data, the constraint on $\sum m_{\nu}$ can be significantly improved, $\sum m_{\nu}<0.161$ eV (95% C.L.). Assuming that the primordial fluctuations are adiabatic with a power law spectrum, within the $\Lambda$CDM model, we find that the upper limit on the ratio of the tensor to scalar is $r<0.200$ (95% C.L.) and the inflationary models with the slope $n_s\geq1$ are excluded at more than $2 \sigma$ confidence level. However, in the framework of dynamical dark energy models, the allowed region in the parameter space of ($n_s$,$r$) is enlarged significantly. Finally, we find no evidence for the large running of the spectral index. (Abridged)Comment: 8 pages, 5 figures, 2 tables, More discussion on NE

Discovery and Identification of W' and Z' in SU(2) x SU(2) x U(1) Models at the LHC

We explore the discovery potential of W' and Z' boson searches for various SU(2) x SU(2) x U(1) models at the Large Hadron Collider (LHC), after taking into account the constraints from low energy precision measurements and direct searches at both the Tevatron (1.96 TeV) and the LHC (7 TeV). In such models, the W' and Z' bosons emerge after the electroweak symmetry is spontaneously broken. Two patterns of the symmetry breaking are considered in this work: one is SU(2)_L x SU(2)_2 x U(1)_X to SU(2)_L x U(1)_Y (BP-I), another is SU(2)_1 x SU(2)_2 x U(1)_Y to SU(2)_L x U(1)_Y (BP-II). Examining the single production channel of W' and Z' with their subsequent leptonic decays, we find that the probability of detecting W' and Z' bosons in the considered models at the LHC (with 14 TeV) is highly limited by the low energy precision data constraints. We show that observing Z' alone, without seeing a W', does not rule out new physics models with non-Abelian gauge extension, such as the phobic models in BP-I. Models in BP-II would predict the discovery of degenerate W' and Z' bosons at the LHC.Comment: 29 pages, including 11 figures, 3 tables, added references for introductio