118462765
Dark matter in the little Higgs model under current experimental constraints from the LHC, Planck, and Xenon data
We examine the status of dark matter (heavy photon) in the littlest Higgs model with T parity (LHT) in light of the new results from the LHC Higgs search, the Planck dark matter relic density, and the XENON100 limit on the dark matter scattering off the nucleon. We obtain the following observations: (i) For the LHC Higgs data, the LHT can well be consistent with the CMS results but disfavored by the ATLAS observation of diphoton enhancement; (ii) for the dark matter relic density, the heavy photon in the LHT can account for the Planck data for the small mass splitting of mirror lepton and heavy photon; (iii) for the dark matter scattering off the nucleon, the heavy photon can give a spin-independent cross section below the XENON100 upper limit for m(AH) > 95 GeV (f > 665 GeV); (iv) a fit using the CMS Higgs data gives the lowest chi square of 2.63 (the standard model value is 4.75) at f similar or equal to 1120 GeV and m(AH) similar or equal to 170 GeV (at this point, the dark matter constraints from Planck and XENON100 can also be satisfied). Such a best point and its nearby favored region (even for an f value up to 3.8 TeV) can be covered by the future XENON1T (2017) experiment.
118505781
A SM-like Higgs near 125 GeV in low energy SUSY: a comparative study for MSSM and NMSSM
A bstractMotivated by the recent LHC hints of a Higgs boson around 125 GeV, we assume a SM-like Higgs with the mass 123-127 GeV and study its implication in low energy SUSY by comparing the MSSM and NMSSM. We consider various experimental constraints at 2σ level (including the muon g − 2 and the dark matter relic density) and perform a comprehensive scan over the parameter space of each model. Then in the parameter space which is allowed by current experimental constraints and also predicts a SM-like Higgs in 123-127 GeV, we examine the properties of the sensitive parameters (like the top squark mass and the trilinear coupling At) and calculate the rates of the di-photon signal and the V V* (V = W, Z) signals at the LHC. Our typical findings are: (i) In the MSSM the top squark and At must be large and thus incur some fine-tuning, which can be much ameliorated in the NMSSM; (ii) In the MSSM a light stau is needed to enhance the di- photon rate of the SM-like Higgs to exceed its SM prediction, while in the NMSSM the di-photon rate can be readily enhanced in several ways; (iii) In the MSSM the signal rates of pp → h → V V* at the LHC are never enhanced compared with their SM predictions, while in the NMSSM they may get enhanced significantly; (iv) A large part of the parameter space so far survived will be soon covered by the expected XENON100(2012) sensitivity (especially for the NMSSM).
118371318
The SM extension with color-octet scalars: diphoton enhancement and global fit of LHC Higgs data
A bstractIn light of the significant progress of the LHC to determine the properties of the Higgs boson, we investigate the capability of the Manohar-Wise model in explaining the Higgs data. This model extends the SM by one family of color-octet and isospin-doublet scalars, and it can sizably alter the coupling strengths of the Higgs boson with gluons and photons. We first examine the current constraints on the model, which are from unitarity, the LHC searches for the scalars and the electroweak precision data (EWPD). In implementing the unitarity constraint, we use the properties of the SU(3) group to simplify the calculation. Then in the allowed parameter space we perform a fit of the model, using the latest ATLAS and CMS data, respectively. We find that the Manohar-Wise model is able to explain the data with χ2 significantly smaller than the SM value. We also find that the current Higgs data, especially the ATLAS data, are very powerful in further constraining the parameter space of the model. In particular, in order to explain the γγ enhancement reported by the ATLAS collaboration, the sign of the hgg coupling is usually opposite to that in the SM.
16593749
Recent Electroweak Results from the Tevatron
W and Z bosons are mainly produced via quark-antiquark annihilations at the Fermilab Tevatron collider. Precision measurements with these gauge bosons provide us with high precision tests of the Standard Model (SM) as well as indirect search for possible new physics beyond the SM. I present the recent electroweak measurements related to single W, Z boson and diboson productions from the CDF and D0 experiments at the Fermilab Tevatron collider.
118072320
Particle Radiation From Gibbons-Maeda Black Hole
This paper investigates the particle radiation from Gibbons-Maeda black hole. Taking into account the self-gravitation of the particle, we calculate the tunnelling rate of the massless particle across the horizon, then we promote the work to the radiation of the charged particle. The calculations prove that the rate of tunnelling equals precisely the exponent of the difference of the black hole entropy before and after emission and the radiation spectrum deviates from exact thermal. The conclusion supports the viewpoint of information conservation.
119267737
Application of higher order holonomy corrections to the perturbation theory of cosmology
Applying the higher order holonomy corrections to the perturbation theory of cosmology, the lattice power law of loop quantum cosmology, , is analyzed and the range of β is decided to be [−1,0] which is different from the conventional range −0.1319 > β ≥ −5/2 (Bojowald M and Hossain G M 2008 Phys. Rev. D 77 023508). At the same time, we find that there is an anomaly-free condition in this theory, and we obtain this condition in the vector and tensor mode. We also find that the nonzero mass of a gravitational wave essentially results from the quantum nature of the Riemannian geometry of loop quantum gravity.
117009475
Quantum effect on luminosity-redshift relation
There are many different proposals for a theory of quantum gravity. Even leaving aside the fundamental difference among theories such as the string theory and the non-perturbative quantum gravity, we are still left with many ambiguities (and/or parameters to be determined) with regard to the choice of variables, the choice of related groups, etc. Loop quantum gravity is also in such a state. It is interesting to search for experimental observables to distinguish these quantum schemes. This paper investigates the loop quantum gravity effect on luminosity-redshift relation. The quantum bounce behavior of loop quantum cosmology is found to result in multivalued correspondence in luminosity-redshift relation. And the detail multivalued behavior can tell the difference of different quantum parameters. The inverse volume quantum correction does not result in bounce behavior in this model, but affects luminosity-redshift relation also significantly.
118012906
Electroweak and QCD Results from the Tevatron
The Tevatron collider has been remarkably successful and has so far delivered more than 11 fb{sup -1} of data to both the CDF and D0 experiments. Though the LHC has replaced the Tevatron as the world's most powerful collider, years of detector calibration, the huge size of the dataset and the nature of pp collisions will keep the Tevatron competitive in many selected topics in the near future. More than 10 fb{sup -1} of data has been collected by each experiment. Good understanding of the detector performance has been demonstrated by the high precision W boson mass ({Delta}M{sub W} = 31 MeV) and top quark mass ({Delta}M{sub t} = 1.06 GeV) measurements. We report the latest electroweak and QCD results from both experiments. Most analyses presented here used 4-6 fb{sup -1} of data.