Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2017-08-03
Abstract: 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 → µτ excess measured at CMS and as well as the (g − 2)µ anomaly could be simultaneously explained within certain parameter spaces that can also tolerate the data on the flavor-violating processes τ → µγ 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2017-08-03
Abstract: 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2017-08-03
Abstract: 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-14
Abstract: 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燤QG. 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,燤QG>5.05�014燝eV, is from GRB 140622A.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract: 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract: 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-13
Abstract: 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∘.
Peer Review Status:Awaiting Review