123143121
Gravitational wave detection: stochastic resonance method with matched filtering
Along with the development of the interferometric gravitational wave detector, we enter into an epoch of the gravitational wave astronomy, which will open a brand new window for astrophysics to observe our universe. However, the gravitational wave detection is a typical weak signal detection, and this weak signal is buried in a strong instrument noise. To our knowledge, almost all of the data analysis methods in gravitational wave detection at present are based on a matched filtering. So it is desirable to take advantage of stochastic resonance methods. However, the all of the stochastic resonance methods are general based on a Fourier transformation and fall short of the matched filtering as a usable technique. In this paper we relate the stochastic resonance to the matched filtering. Our results show that the stochastic resonance can indeed be combined with the matched filtering for both the periodic and the non-periodic input signal. This encouraging result will be the first step to apply the stochastic resonance to the matched filtering in gravitational wave detection. Moreover, based on the matched filtering, we firstly propose a novel measurement method for the stochastic resonance which is valid for both the periodic and the non-periodic driven signal.
122770000
Quantum thermal effect of arbitrarily accelerating Kinnersley black hole
The Hawking radiation of an arbitrarily accelerating Kinnersley black hole is studied. We obtain the event horizon equation and the Hawking thermal spectrum formula. Both the location and the temperature of the event horizon depend on the time and the angles. We recover the well-known results when the acceleration vanishes.
119220991
Warm inflation in loop quantum cosmology: a model with a general dissipative coefficient
A general form of warm inflation with the dissipative coefficient $\ensuremath{\Gamma}={\ensuremath{\Gamma}}_{0}(\ensuremath{\phi}/{\ensuremath{\phi}}_{0}{)}^{n}(T/{\ensuremath{\tau}}_{0}{)}^{m}$ in loop quantum cosmology is studied. In this case, we obtain conditions for the existence of a warm inflationary attractor in the context of loop quantum cosmology by using the method of stability analysis. The two cases when the dissipative coefficient is independent ($m=0$) and dependent ($m\ensuremath{\ne}0$) on temperature are analyzed specifically. In the latter case, we use the new power spectrum which should be used when considering temperature dependence in the dissipative coefficient. We find that the thermal effect is enhanced in the case $mg0$. As in the standard inflation in loop quantum cosmology, we also reach the conclusion that quantum effect leaves a tiny imprint on the cosmic microwave background sky.
119115738
Note on the super-inflation in loop quantum cosmology
Abstract Phenomenological effect of the super-inflation in loop quantum cosmology (LQC) is discussed. We investigate the case that the Universe is filled with the interacting field between massive scalar field and radiation. Considering the damping coefficient Γ as a constant, the changes of the scale factor during super-inflation with four different initial conditions are discussed, and we find that the changes of the scale factor depends on the initial values of energy density of the scalar field and radiation at the bounce point. But no matter which initial condition is chosen, the radiation always dominated at the late time. Moreover, we investigate whether the super-inflation can provide enough e-folding number. For the super-inflation starts from the quantum bounce point, the initial value of Hubble parameter H ( t i ) ∼ 0 , then it is possible to solve the flatness problem and horizon problem. As an example, following the method of [18] to calculate particle horizon on the condition that the radiation dominated at bounce point, and we find that the Universe has had enough time to be homogeneous and isotopic.
119282417
Loop quantum cosmology of Bianchi I model in $\bar{\mu }$ and $\bar{\mu }^{\prime }$ schemes with higher order holonomy corrections
The detailed formulation of loop quantum cosmology with higher order holonomy corrections has been constructed recently in the homogeneous and isotropic spacetime, yet it is important to extend the higher order holonomy corrections to include the effects of anisotropy which typically grow during the collapsing phase. In this paper we investigate the Bianchi I model in scheme which truly captures the regularization of the Hamiltonian constraint. To compare with the earlier works and provide a comparison with the scheme, we also investigate the scheme although it has many disadvantages. First we construct the effective dynamics with higher order holonomy corrections in a massless scalar field, then we extend it to the inclusion of arbitrary matter. Besides that, we also analyze the behavior of the anisotropy during the evolution of the universe. We find that in the scheme, the singularity is never approached and the quantum bounce is generic as in the isotropic case, regardless of the order of the holonomy corrections. Some differences in the bouncing phase of the two schemes are also found out. It is also shown that in the two schemes the behavior of the anisotropy is not the same before and after the bounce.
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.
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.
119235151
Higgs decay to dark matter in low energy SUSY: is it detectable at the LHC?
A bstractDue to the limited statistics so far accumulated in the Higgs boson search at the LHC, the Higgs boson property has not yet been tightly constrained and it is still allowed for the Higgs boson to decay invisibly to dark matter with a sizable branching ratio. In this work, we perform a comparative study for the Higgs decay to neutralino dark matter by considering three different low energy SUSY models: the minimal supersymmetric standard model (MSSM), the next-to-minimal supersymmetric standard models (NMSSM) and the nearly minimal supersymmetric standard model (nMSSM). Under current experimental constraints at 2σ level (including the muon g − 2 and the dark matter relic density), we scan over the parameter space of each model. Then in the allowed parameter space we calculate the branching ratio of the SM-like Higgs decay to neutralino dark matter and examine its observability at the LHC by considering three production channels: the weak boson fusion VV → h, the associated production with a Z-boson pp → hZ + X or a pair of top quarks $pp \to ht\overline t + X$. We find that in the MSSM such a decay is far below the detectable level; while in both the NMSSM and nMSSM the decay branching ratio can be large enough to be observable at the LHC. We conclude that at the LHC the interplay of detecting such an invisible decay and the visible di-photon decay may allow for a discrimination of different SUSY models.
119294466
Little Higgs theory confronted with the LHC Higgs data
We confront the little Higgs theory with the LHC Higgs search data (up to 17 fb(-1) of the combined 7 and 8 TeV run). Considering some typical models, namely, the littlest Higgs model, the littlest Higgs model with T parity (LHT-A and LHT-B), and the simplest little Higgs model, we scan over the parameter space in the region allowed by current experiments. We find that in these models the inclusive and exclusive (via gluon-gluon fusion) diphoton and ZZ* signal rates of the Higgs boson are always suppressed and approach the standard model predictions for a large-scale f. Thus, the ZZ* signal rate is within the 1 sigma range of the experimental data while the inclusive diphoton signal rate is always outside the 2 sigma range. Especially, in the LHT-A the diphoton signal rate is outside the 3 sigma range of the experimental data for f < 800 GeV. We also perform a global chi(2) fit to the available LHC and Tevatron Higgs data, and find that these models provide no better global fit to the whole data set (only for some special channels a better fit can be obtained, especially in the LHT-B). DOI: 10.1103/PhysRevD.87.055004
118683449
Higgs phenomenology in the Minimal Dilaton Model after Run I of the LHC
A bstractThe Minimal Dilaton Model (MDM) extends the Standard Model (SM) by a singlet scalar, which can be viewed as a linear realization of general dilaton field. This new scalar field mixes with the SM Higgs field to form two mass eigenstates with one of them corresponding to the 125 GeV SM-like Higgs boson reported by the LHC experiments. In this work, under various theoretical and experimental constrains, we perform fits to the latest Higgs data and then investigate the phenomenology of Higgs boson in both the heavy dilaton scenario and the light dilaton scenario of the MDM. We find that: (i) if one considers the ATLAS and CMS data separately, the MDM can explain each of them well, but refer to different parameter space due to the apparent difference in the two sets of data. If one considers the combined data of the LHC and Tevatron, however, the explanation given by the MDM is not much better than the SM, and the dilaton component in the 125-GeV Higgs is less than about 20 % at 2σ level. (ii) The current Higgs data have stronger constrains on the light dilaton scenario than on the heavy dilaton scenario. (iii) The heavy dilaton scenario can produce a Higgs triple self coupling much larger than the SM value, and thus a significantly enhanced Higgs pair cross section at hadron colliders. With a luminosity of 100 fb−1 (10 fb−1) at the 14-TeV LHC, a heavy dilaton of 400 GeV (500 GeV) can be examined. (iv) In the light dilaton scenario, the Higgs exotic branching ratio can reach 43 % (60 %) at 2σ (3σ) level when considering only the CMS data, which may be detected at the 14-TeV LHC with a luminosity of 300 fb−1 and the Higgs Factory.
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).