Current Location:home > Browse

1. chinaXiv:201708.00112 [pdf]

Type-III two Higgs doublet model plus a pseudoscalar confronted with h → ?τ , muon g ? 2 and dark matter

Xuewen Liu; Ligong Bian; Xue-Qian Li Jing Shu
Subjects: Physics >> The Physics of Elementary Particles and Fields

In this work, we introduce an extra singlet pseudoscalar into the Type-III two Higgs doublet model (2HDM) which is supposed to solve a series of problems in the modern particle-cosmology. With existence of a light pseudoscalar, the h → ?τ excess measured at CMS and as well as the (g ? 2)? anomaly could be simultaneously explained within certain parameter spaces that can also tolerate the data on the flavor-violating processes τ → ?γ and Higgs decay gained at LHC. Within the same parameter spaces, the DM relic abundance is well accounted. Moreover, the recently observed Galactic Center gamma ray excess(GCE) is proposed to realize through dark matter(DM) pair annihilations, and in this work, the scenario of the annihilation being mediated by the pseudoscalar is also addressed.

submitted time 2017-08-03 Hits1455Downloads811 Comment 0

2. chinaXiv:201708.00110 [pdf]

Interference E#11;ect on Resonance Studies in Searches of Heavy Particles

Ligong Bian; Da Liu; Jing Shu; Yongchao Zhang
Subjects: Physics >> The Physics of Elementary Particles and Fields

The interference between resonance signal and continuum background can be either constructive or destructive, depending on the relative sign of couplings between the signal and background amplitudes. Different interference schemes lead to asymmetric distortions of the resonance line shape, which could be distinguished in experiments, when the internal resonance width is larger than the detector resolution. Interpreting the ATLAS diboson excesses by means of a toy W' model as an illustrative example (though it is disfavored by the 13 TeV data), we find that the signs of resonance couplings can only be revealed in the line shape measurements up to a high confidence level at a high luminosity, which could bring us further information on the underlying theory beyond resonance searches at future lepton and hadron colliders.

submitted time 2017-08-03 Hits1273Downloads684 Comment 0

3. chinaXiv:201708.00108 [pdf]

A hidden confining world on the 750 GeV diphoton excess

Ligong Bian; Ning Chen; Da Liu; Jing Shu
Subjects: Physics >> The Physics of Elementary Particles and Fields

We explain the recent diphoton excesses around 750 GeV by both ATLAS and CMS as a singlet scalar Φ which couples to SM gluon and neutral gauge bosons only through higher dimensional operators. A natural explanation is that Φ is a pseudo-Nambu-Goldstone boson (pNGB) which receives parity violation through anomaly if there exists a hidden strong dynamics. The singlet and other light pNGBs will decay into two SM gauge bosons and even serves as the meta-stable coloured states which can be probed in the future. By accurately measuring their relative decay and the total production rate in the future, we will learn the underlying strong dynamics parameter. The lightest baryon in this confining theory could serve as a viable dark matter candidate.

submitted time 2017-08-03 Hits1312Downloads716 Comment 0

4. chinaXiv:201609.00964 [pdf]

Constraining the Lorentz invariance violation from the continuous spectra of short gamma-ray bursts

Zhe Chang; Xin Li; Hai-Nan Lin; Yu Sang; Ping Wang; Sai Wang
Subjects: Physics >> Nuclear Physics

In quantum gravity, a foamy structure of space-time leads to Lorentz invariance violation (LIV). As the most energetic astrophysical processes in the Universe, gamma-ray bursts (GRBs) provide an effective way to probe quantum gravity effects. We use continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale MQG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to the low energy ones. Based on the fact that the LIV-induced time delay can't be longer than the duration of a GRB, we present the most conservative estimation of the quantum gravity energy scales from 20 short GRBs. The most strict constraint,MQG>5.05* 1014 GeV, is from GRB 140622A.

submitted time 2016-09-14 Hits1358Downloads828 Comment 0

5. chinaXiv:201609.00910 [pdf]

Testing the isotropy of the Universe by using the JLA compilation of type-Ia supernovae

Hai-Nan Lin; Sai Wang; Zhe Chang; Xin Li
Subjects: Physics >> Nuclear Physics

We probe the possible anisotropy of the Universe by using the JLA compilation of type-Ia supernovae. We apply the Markov Chain Monte Carlo (MCMC) method to constrain the amplitude and direction of anisotropy in three cosmological models. For the dipole-modulated?ΛCDM model, the anisotropic amplitude is consistent with zero at?68%?C.L., and has an upper bound?AD<1.98×10?3?at?95%?C.L. Regardless of much larger uncertainty, we find the dipole direction of JLA is amazingly opposite to that of Union2. Similar results are found for the dipole-modulated?wCDM and CPL models. Thus, the Universe is still well consistent with the isotropy according to the JLA compilation.

submitted time 2016-09-13 Hits1199Downloads673 Comment 0

6. chinaXiv:201609.00876 [pdf]

Anisotropic inflation in Finsler spacetime

Xin Li; Sai Wang; Zhe Chang
Subjects: Physics >> Nuclear Physics

We suggest the universe is Finslerian in the stage of inflation. The Finslerian background spacetime breaks rotational symmetry and induces parity violation. The primordial power spectrum is given for quantum fluctuation of the inflation field. It depends not only on the magnitude of wavenumber but also on the preferred direction. We derive the gravitational field equations in the perturbed Finslerian background spacetime, and obtain a conserved quantity outside the Hubble horizon. The angular correlation coefficients are presented in our anisotropic inflation model. The parity violation feature of Finslerian background spacetime requires that the anisotropic effect only appears in angular correlation coefficients if?l′=l+1. The numerical results of the angular correlation coefficients are given to describe the anisotropic effect.

submitted time 2016-09-13 Hits1216Downloads653 Comment 0

7. chinaXiv:201609.00873 [pdf]

A unified description for dipoles of the fine-structure constant and SnIa Hubble diagram in Finslerian universe

Xin Li; Hai-Nan Lin; Sai Wang; Zhe Chang
Subjects: Physics >> Nuclear Physics

We propose a Finsler spacetime scenario of the anisotropic universe. The Finslerian universe requires both the fine-structure constant and accelerating cosmic expansion have dipole structure, and the directions of these two dipoles are the same. Our numerical results show that the dipole direction of SnIa Hubble diagram locates at?(l,b)=(314.6?±20.3?,?11.5?±12.1?)?with magnitude?B=(?3.60±1.66)×10?2. And the dipole direction of the fine-structure constant locates at?(l,b)=(333.2?±8.8?,?12.7?±6.3?)?with magnitude?B=(0.97±0.21)×10?5. The angular separation between the two dipole directions is about?18.2?.

submitted time 2016-09-13 Hits1191Downloads688 Comment 0

  [1 Pages/ 7 Totals]