所有结果

Learning from Higgs Physics at Future Higgs Factories

Jiayin Gu; Honglei Li; Zhen Liu; Shufang Su; Wei Su分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

Future Higgs factories can reach impressive precision on Higgs property measurements.In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explored its sensitivity to new physics models at the electron-positron colliders. In particular, we studied two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weaklyinteracting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong nteracting models as examples of strong dynamics. We performed a global t to various Higgs search channels to obtain the 95% C.L.constraints on the model parameter space. In the SM with a singlet xtension, we obtained the limits on the singlet-doublet mixing angle sin , as well as the more general Wilson coe cients of the induced higher dimensional operators. In the 2HDM, we analyzed tree level e ects in tan vs. cos(β-α) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for di erent types of 2HDM. In strong dynamics models, we obtained lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish di erent models. We also compared the sensitivity of various future Higgs factories,namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC). |

Is GW151226 a really signal of gravitational wave?

Zhe Chang; Chao-Guang Huang; Zhi-Chao Zhao分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

Recently, the LIGO Scientiﬁc Collaboration and Virgo Collaboration published the second observation on gravitational wave GW151226 [Phys. Rev. Lett. 116, 241103 (2016)] from the binary black hole coalescence with initial masses about 14 M and 8 M. They claimed that the peak gravitational strain was reached at about 450 Hz, the inverse of which has been longer than the average time a photon staying in the Fabry-Perot cavities in two arms. In this case, the phase-diﬀerence of a photon in the two arms due to the propagation of gravitational wave does not always increase as the photon stays in the cavities. It might even be cancelled to zero in extreme cases. When the propagation eﬀect is taken into account, we ﬁnd that the claimed signal GW151226 would almost disappear. |

Power Law of Shear Viscosity in Einstein-Maxwell-Dilaton-Axion model

Yi Ling; Zhuoyu Xian; Zhenhua Zhou分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

We construct charged black hole solutions with hyperscaling violation in the infrared(IR) region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is testi ed numerically at low temperature T, namely, =s T , where the values of exponent coincide with the analytical results. We also nd that the exponent is not a ected by irrelevant current, but is reduced by the relevant current. |

Note on the butterfly effect in holographic superconductor models

Yi Ling; Peng Liu; Jian-Pin Wu分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

In this note we remark that the butterfly effect can be used to diagnose the phase transition of superconductivity in a holographic framework. Speci cally, we compute the butterfly velocity in a charged black hole background as well as anisotropic backgrounds with Q-lattice structure. In both cases we nd its derivative to the temperature is discontinuous at critical points. We also ropose that the butterfly velocity can signalize the occurrence of thermal phase transition in general holographic models. |

CMB anomalies from an inflationary model in string theory

Zhi-Guo Liu; Zong-Kuan Guo; Yun-Song Piao分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

Recent Planck measurements show some CMB anomalies on large angular scales, which confirms the early observations by WMAP. We show that an inflationary model, in which before the slow-roll inflation the Universe is in a superinflationary phase, can generate a large-scale cutoﬀ in the primordial power spectrum, which may account for not only the power suppression on large angular scales, but also a large dipole power asymmetry in the CMB. We discuss an implementation of our model in string theory. |

Obtaining the CMB anomalies with a bounce from the contracting phase to inflation

Zhi-Guo Liu; Zong-Kuan Guo; Yun-Song Piao分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

Recent Planck data show the anomalies of CMB fluctuations on large angular scales, which confirms the early observations by WMAP. We continue studying an inflationary model, in which before the slow roll inflation the universe is in a contracting phase, and fit the model with the Planck data. It is showed that this model may generate not only the power deficit at low-l, but also a large hemispherical power asymmetry in CMB. We also discuss the implication of the result to the eternal inflation scenario. |

分类： 物理学 >> 核物理学

The intrinsic nuclear shapes deviating from a sphere not only man- ifest themselves in nuclear collective states but also play impor- tant roles in determining nuclear potential energy surfaces (PES’s) and fission barriers. In order to describe microscopically and self- consistently nuclear shapes and PES’s with as many shape degrees of freedom as possible included, we developed multidimensionally- constrained covariant density functional theories (MDC-CDFTs). In MDC-CDFTs, the axial symmetry and the reflection symmetry are both broken and all deformations characterized by βλμ with even μ are considered. We have used the MDC-CDFTs to study PES’s and fission barriers of actinides, the non-axial octupole Y32 correla- tions in N = 150 isotones and shapes of hypernuclei. In this Review we will give briefly the formalism of MDC-CDFTs and present the applications to normal nuclei. |

Systematics of capture and fusion dynamics in heavy-ion collisions

Bing Wang; Kai Wen; Wei-Juan Zhao; En-Guang Zhao; Shan-Gui Zhou分类： 物理学 >> 核物理学

We perform a systematic study of capture excitation functions by using an empirical coupled-channel model. In this model, a barrier distribution is used to take effectively into account the effects of couplings between the relative motion and intrinsic degrees of freedom. The shape of the barrier distribution is of an asymmetric Gaussian form. The effect of neutron transfer channels is also included in the barrier distribution. Based on the interaction potential between the projectile and the target, empirical formulas are proposed to determine the parameters of the barrier distribution. Theoretical estimates for barrier distributions and calculated capture cross sections together with experimental cross sections of 220 reaction systems with 182 ZPZT 1640 are tabulated. The results show that our empirical formulas work quite well in the energy region around the Coulomb barrier. This model can provide prediction of capture cross sections for the synthesis of superheavy nuclei as well as valuable information on capture and fusion dynamics. |

We develop a multidimensionally constrained relativistic Hartree-Bogoliubov (MDC-RHB) model in which the pairing correlations are taken into account by making the Bogoliubov transformation. In this model, the nuclear shape is assumed to be invariant under the reversion of x and y axes; i.e., the intrinsic symmetry group is V4 and all shape degrees of freedom βλμ with even μ are included self-consistently. The RHB equation is solved in an axially deformed harmonic oscillator basis. A separable pairing force of finite range is adopted in the MDC-RHB model. The potential energy curves of neutron-rich even-even Zr isotopes are calculated with relativistic functionals DD-PC1 and PC-PK1 and possible tetrahedral shapes in the ground and isomeric states are investigated. The ground state shape of 110Zr is predicted to be tetrahedral with both functionals and so is that of 112Zr with the functional DD-PC1. The tetrahedral ground states are caused by large energy gaps around Z = 40 and N = 70 when β32 deformation is included. Although the inclusion of the β30 deformation can also reduce the energy around β20 = 0 and lead to minima with pear-like shapes for nuclei around 110Zr, these minima are unstable due to their shallowness. |

Rayleigh scattering of linear alkylbenzene in large liquid scintillator detectors

Xiang Zhou; Qian Liu; Michael Wurm; Qingmin Zhang; Yayun Ding; Zhenyu Zhang; Yangheng Zheng; Li Zhou; Jun Cao; Yifang Wang分类： 物理学 >> 核物理学

Rayleigh scattering poses an intrinsic limit for the transparency of organic liquid scintillators. This work focuses on the Rayleigh scattering length of linear alkylbenzene (LAB), which will be used as the solvent of the liquid scintillator in the central detector of the Jiangmen Underground Neutrino Observatory. We investigate the anisotropy of the Rayleigh scattering in LAB, showing that the resulting Rayleigh scattering length will be significantly shorter than reported before. Given the same overall light attenuation, this will result in a more efficient transmission of photons through the scintillator, increasing the amount of light collected by the photosensors and thereby the energy resolution of the detector. |