118094398
Determining the Unitarity Triangle from Two‐Body Charmless Hadronic B Decays
We performed an updated global fits to charmless Bu,d → PP decays in the framework of flavor SU(3) symmetry, without referring to sin2β measured from the charmonium decay modes. Fit results directly constrain the (ρ, η) vertex of the unitarity triangle. Details regarding the analyses of different schemes of SU(3) breaking in decay amplitude sizes and predictions for the branching ratios and CP asymmetries of Bu,d,s → PP decays are given in Ref. [1].
15356463
Flavor SU(3) analysis of charmless B meson decays to two pseudoscalar mesons
Global fits to charmless B→PP decays in the framework of flavor SU(3) symmetry are updated and improved without reference to the sin 2β measured from the charmonium decay modes. Fit results directly constrain the (,) vertex of the unitarity triangle, and are used to predict the branching ratios and CP asymmetries of all decay modes, including those of the Bs system. Different schemes of SU(3) breaking in decay amplitude sizes are analyzed. The major breaking effect between strangeness-conserving and strangeness-changing decays can be accounted for by including a ratio of decay constants in tree and color-suppressed amplitudes. The possibility of having a new physics contribution to Kπ decays is also examined from the data fitting point of view.
117055056
A study of CP violation in K and B meson decays
119255219
Partially strong WW scattering
What if only a light Higgs boson is discovered at the CERN LHC? Conventional wisdom tells us that the scattering of longitudinal weak gauge bosons would not grow strong at high energies. However, this is generally not true. In some composite models or general two-Higgs-doublet models, the presence of a light Higgs boson does not guarantee complete unitarization of the WW scattering. After partial unitarization by the light Higgs boson, the WW scattering becomes strongly interacting until it hits one or more heavier Higgs bosons or other strong dynamics. We analyze how LHC experiments can reveal this interesting possibility of partially strong WW scattering.
96443947
Discovery in Drell-Yan processes at the LHC
We study the Drell-Yan process mediated by a new bosonic resonance at the LHC. The bosons of spin-0, 1, and 2 with the most general leading-order couplings to standard model fermions and gluons are considered, which provides a model-independent formulation for future exploration of the resonance properties, such as its spin, mass and couplings. In the case of neutral resonances, we demonstrate how the shapes of the kinematical distributions change as one varies the chiral couplings of the quarks and leptons, and show how to analyze the couplings by making use of the forward-backward asymmetry. In the case of charged resonances, we propose a novel technique to effectively reconstruct the angular distribution in the center-of-mass frame, to a large extent avoiding the two-fold ambiguity due to the missing neutrino. Similar to the case of a neutral resonance, the spin information of the resonance can be extracted unambiguously, and chiral couplings and the asymmetries can be explored in a statistical manner. With the current LHC data, we present bounds on the mass and cross section times branching fraction of the new resonance and estimate the future reach.
119109976
Probing leptonic interactions of a family-nonuniversal Z′ boson
A bstractWe explore a Z′ boson with family-nonuniversal couplings to charged leptons. The general effect of Z-Z′ mixing, of both kinetic and mass types, is included in the analysis. Adopting a model-independent approach, we perform a comprehensive study of constraints on the leptonic Z′ couplings from currently available experimental data on a number of flavor-conserving and flavor-changing transitions. Detailed comparisons are made to extract the most stringent bounds on the leptonic couplings. Such information is fed into predictions of various processes that may be experimentally probed in the near future.
12835808
Galaxy redshift surveys with sparse sampling
Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g., Vsurvey ~ 10Gpc3) to be covered, and thus tends to be expensive. A ``sparse sampling'' method offers a more affordable solution to this problem: within a survey footprint covering a given survey volume, Vsurvey, we observe only a fraction of the volume. The distribution of observed regions should be chosen such that their separation is smaller than the length scale corresponding to the wavenumber of interest. Then one can recover the power spectrum of galaxies with precision expected for a survey covering a volume of Vsurvey (rather than the volume of the sum of observed regions) with the number density of galaxies given by the total number of observed galaxies divided by Vsurvey (rather than the number density of galaxies within an observed region). We find that regularly-spaced sampling yields an unbiased power spectrum with no window function effect, and deviations from regularly-spaced sampling, which are unavoidable in realistic surveys, introduce calculable window function effects and increase the uncertainties of the recovered power spectrum. On the other hand, we show that the two-point correlation function (pair counting) is not affected by sparse sampling. While we discuss the sparse sampling method within the context of the forthcoming Hobby-Eberly Telescope Dark Energy Experiment, the method is general and can be applied to other galaxy surveys.
54957266
Constraining the detailed balance condition in Hořava gravity with cosmic accelerating expansion
In 2009 Hořava proposed a power-counting renormalizable quantum gravity theory. Afterwards a term in the action that softly violates the detailed balance condition has been considered with the attempt of obtaining a more realistic theory in its IR-limit. This term is proportional to ωR(3), where ω is a constant parameter and R(3) is the spatial Ricci scalar. In this paper we derive constraints on this IR-modified Hořava theory using the late-time cosmic accelerating expansion observations. We obtain a lower bound of |ω| that is nontrivial and depends on ΛW, the cosmological constant of the three dimensional spatial action in the Hořava gravity. We find that to preserve the detailed balance condition, one needs to fine-tune ΛW such that −2.29 × 10−4 < (c2ΛW)/(H20ΩDE)−2 < 0, where H0 and ΩDE are the Hubble parameter and dark energy density fraction in the present epoch, respectively. On the other hand, if we do not insist on the detailed balance condition, then the valid region for ΛW is much relaxed to −0.39 < (c2ΛW)/(H20ΩDE)−2 < 0.12. We find that although the detailed balance condition cannot be ruled out, it is strongly disfavored.
119227092
Dark matter detection with polarized detectors
Abstract We consider the prospects to use polarized dark-matter detectors to discriminate between various dark-matter models. If WIMPs are fermions and participate in parity-violating interactions with ordinary matter, then the recoil-direction and recoil-energy distributions of nuclei in detectors will depend on the orientation of the initial nuclear spin with respect to the velocity of the detector through the Galactic halo. If, however, WIMPS are scalars, the only possible polarization-dependent interactions are extremely velocity-suppressed and, therefore, unobservable. Since the amplitude of this polarization modulation is fixed by the detector speed through the halo, in units of the speed of light, exposures several times larger than those of current experiments will be required to be probe this effect.