We examine how dark energy constraints from current observational data depend on the analysis methods used: the analysis of Type Ia supernovae (SNe Ia), and that of galaxy clustering data. We generalize the flux-averaging analysis method of SNe Ia to allow correlated errors of SNe Ia, in order to reduce the systematic bias due to weak lensing of SNe Ia. We find that flux-averaging leads to larger errors on dark energy and cosmological parameters if only SN Ia data are used. When SN Ia data (the latest compilation by the SNLS team) are combined with WMAP 7 yr results (in terms of our Gaussian fits to the probability distributions of the CMB shift parameters), the latest Hubble constant ($H_0$) measurement using the Hubble Space Telescope (HST), and gamma ray burst (GRB) data, flux-averaging of SNe Ia increases the concordance with other data, and leads to significantly tighter constraints on the dark energy density at $z=1$, and the cosmic curvature ${\Omega }_k$. The galaxy clustering measurements of $H(z=0.35)r_s(z_d)$ and $r_s(z_d)/D_A(z=0.35)$ (where $H(z)$ is the Hubble parameter, $D_A(z)$ is the angular diameter distance, and $r_s(z_d)$ is the sound horizon at the drag epoch) by Chuang & Wang (2011) are consistent with SN Ia data, given the same pirors ($\mathrm{CMB}+H_0+\mathrm{GRB}$), and lead to significantly improved dark energy constraints when combined. Current data are fully consistent with a cosmological constant and a flat universe.

The geometrical adhesion model that we described in previous papers provides a fully solved model for the nonlinear evolution of fields that mimics the cosmological evolution of pressureless fluids. In this context, we explore the expected late-time properties of the cosmic propagators once halos have formed, in a regime beyond the domain of application of perturbation theories. Whereas propagators in Eulerian coordinates are closely related to the velocity field, we show here that propagators defined in Lagrangian coordinates are intimately related to the halo mass function. Exact results can be obtained in the one-dimensional case. In higher dimensions, the computations are more intricate because of the dependence of the propagators on the detailed shape of the underlying Lagrangian-space tessellations, that is, on the geometry of the regions that eventually collapse to form halos. We illustrate these results for both the one-dimensional and the two-dimensional dynamics. In particular, we give here the expected asymptotic behaviors obtained for power-law initial power spectra. These analytical results are compared with the results obtained with dedicated numerical simulations.

Cosmic ray antiprotons provide an important probe to study the cosmic ray propagation in the interstellar space and to investigate the existence of dark matter. Acting the Earth-Moon system as a magnetic spectrometer, paths of primary antiprotons are deflected in the opposite sense with respect to those of the protons in their way to the Earth. This effect allows, in principle, the search for antiparticles in the direction opposite to the observed deficit of cosmic rays due to the Moon (the so-called “Moon shadow”). The ARGO-YBJ experiment, located at the Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China, 4300 m a.s.l., $606\mathrm{g}/{\mathrm{cm}}^2$), is particularly effective in measuring the cosmic ray antimatter content via the observation of the cosmic rays shadowing effect due to: (1) good angular resolution, pointing accuracy and long-term stability; (2) low energy threshold; (3) real sensitivity to the geomagnetic field. Based on all the data recorded during the period from July 2006 through November 2009 and on a full Monte Carlo simulation, we searched for the existence of the shadow cast by antiprotons in the TeV energy region. No evidence of the existence of antiprotons is found in this energy region. Upper limits to the $\overline{p}/p$ flux ratio are set to 5% at a median energy of 1.4 TeV and 6% at 5 TeV with a confidence level of 90%. In the TeV energy range these limits are the lowest available.

Subject to strong experimental constraints at low energies, baryon number violation is nonetheless well motivated from a theoretical point of view. We examine the possibility of observing baryon-number-violating top-quark production or decay at hadron colliders. We adopt a model-independent effective approach and focus on operators with minimal mass dimension. Corresponding effective coefficients could be directly probed at the Large Hadron Collider (LHC) already with an integrated luminosity of $1{\mathrm{fb}}^{-1}$ at 7 TeV, and further constrained with $30(100){\mathrm{fb}}^{-1}$ at 7 (14) TeV.

An Abelian gauge extension of the standard model is proposed with a fourth generation. The fourth-generation fermions obtain their masses from a heavier Higgs doublet which makes no tree- level contributions to the first three generations’ masses. Light first-three-generations’ neutrino masses continue to have a type-I seesaw explanation, whereas the fourth-generation neutrino turns out to be a heavy Dirac neutrino. In the minimal version of such a model with no off-diagonal Yukawa couplings between the fourth and the first three generations, such a heavy Dirac neutrino can be long-lived on cosmological time scales. In this model, the stated LHC exclusion range $120\mathrm{GeV}<m_H<600\mathrm{GeV}$ on the lighter Higgs placed in the context of a generic fourth-generation standard model is evaded. Also, the Dirac fourth-generation neutrino in this model, if stable, would constitute up to 1% of the cold dark matter in the Universe.

Hypothetical long-lived massive colored particles (MCPs or $Y\mathrm{s}$) would be confined in colorless exotic strongly interacting massive particles (SIMPs) at a color confinement temperature of $T_{\mathrm{C}}\sim 200\mathrm{MeV}$. Two long-lived MCPs form a bound state ($Y\overline{Y}$) at collisions of two SIMPs. We study sensitivities of MCP annihilation to decay properties of resonances ($Y\overline{Y}$), and binding energies or energy levels of exotic SIMPs. The ($Y\overline{Y}$) formation is assumed to dominantly proceed through resonances of ($Y\overline{Y}$) in this paper. We make a toy model of the effective cross section for $Y\overline{Y}$ annihilation. Abundances of SIMPs are then calculated for different sets of parameters specifying properties of ($Y\overline{Y}$) resonances, binding energies of SIMPs, the initial abundance and the mass of MCP. Calculated relic abundances for respective SIMP species are $2\times {10}^{-8}–3\times {10}^{-4}$ times that of baryon. They can be much higher but cannot be much smaller than the previous estimate. The abundances can be consistent depending on parameters with the possible scenario that SIMPs bind to nuclei and subsequent exotic nuclear reactions reduce the primordial abundance of ${}^7\mathrm{Li}$ or enhance those of ${}^9\mathrm{Be}$ and/or B in the early Universe. A unique information on the quark-hadron phase transition in the early Universe may become available in future by elaborated studies on the annihilation process with light element abundances as observables.

The microscopic spectral density of the Hermitian Wilson-Dirac operator is computed numerically in quenched lattice QCD. We demonstrate that the results given for fixed index of the Wilson-Dirac operator can be matched by the predictions from Wilson chiral perturbation theory. We test successfully the finite volume and the mass scaling predicted by Wilson chiral perturbation theory at fixed lattice spacing.

The SU(2) gauge theory with two massless Dirac flavors constitutes the building block of several models of Technicolor. Furthermore it has also been used as a template for the construction of a natural light asymmetric, or mixed type, dark matter candidate. We use explicit lattice simulations to confirm the pattern of chiral symmetry breaking by determining the Goldstone spectrum and therefore show that the dark matter candidate can, de facto, be constituted by a complex Goldstone boson. We also determine the phenomenologically relevant spin-one and spin-zero isovector spectrum and demonstrate that it is well separated from the Goldstone spectrum.

Wilson chiral perturbation theory (WChPT) is the effective field theory describing the long-distance properties of lattice QCD with Wilson or twisted-mass fermions. We consider here WChPT for the theory with two light flavors of Wilson fermions or a single light twisted-mass fermion. Discretization errors introduce three low energy constants into partially quenched WChPT at $\mathcal{O}(a^2)$, conventionally called $W_6^{\prime }$, $W_7^{\prime }$, and $W_8^{\prime }$. The phase structure of the theory at nonzero $a$ depends on the sign of the combination $2W_6^{\prime }+W_8^{\prime }$, while the spectrum of the lattice Hermitian Wilson-Dirac operator depends on all three constants. It has been argued, based on the positivity of partition functions of fixed topological charge, and on the convergence of graded group integrals that arise in the $ϵ$ regime of WChPT, that there is a constraint on the low energy constants arising from the underlying lattice theory. In particular, for $W_6^{\prime }=W_7^{\prime }=0$, the constraint found is $W_8^{\prime }\le 0$. Here we provide an alternative line of argument, based on mass inequalities for the underlying partially quenched theory. We find that $W_8^{\prime }\le 0$, irrespective of the values of $W_6^{\prime }$ and $W_7^{\prime }$. Our constraint implies that $2W_6^{\prime }>|W_8^{\prime }|$ if the phase diagram is to be described by the first-order scenario, as recent simulations suggest is the case for some choices of action.

We consider a low-energy effective theory for the $X(3872)$ (XEFT) that can be used to systematically analyze the decay and production of the $X(3872)$ meson, assuming that it is a weakly bound state of charmed mesons. In a previous paper, we calculated the decays of $X(3872)$ into ${\chi }_{cJ}$ plus pions using a two-step procedure in which Heavy Hadron Chiral Perturbation Theory ($\mathrm{HH}\chi \mathrm{PT}$) amplitudes are matched onto XEFT operators and then $X(3872)$ decay rates are calculated using these operators. The procedure leads to IR divergences in the three-body decay $X(3872)\to {\chi }_{cJ}\pi \pi$ when virtual $D$ mesons can go on shell in tree level $\mathrm{HH}\chi \mathrm{PT}$ diagrams. In previous work, we regulated these IR divergences with the $D^{*0}$ width. In this work, we carefully analyze $X(3872)\to {\chi }_{cJ}{\pi }^0$ and $X(3872)\to {\chi }_{cJ}\pi \pi$ using the operator product expansion in XEFT. Forward scattering amplitudes in $\mathrm{HH}\chi \mathrm{PT}$ are matched onto local operators in XEFT, the imaginary parts of which are responsible for the decay of the $X(3872)$. Here we show that the IR divergences are regulated by the binding momentum of the $X(3872)$ rather than the width of the $D^{*0}$ meson. In the operator product expansion, these IR divergences cancel in the calculation of the matching coefficients so the correct predictions for the $X(3872)\to {\chi }_{c1}\pi \pi$ do not receive enhancements due to the width of the $D^{*0}$. We give updated predictions for the decay $X(3872)\to {\chi }_{c1}\pi \pi$ at leading order in XEFT.

The compatibility of the Frobenius group $T_{13}$ with the canonical seesaw mechanism of neutrino mixing is examined. The standard model is extended minimally by introducing a family symmetry and three right-handed neutrinos. To fit experiments and place constraints on the possibilities, tribimaximal mixing is used as a guideline. The application of both a family symmetry group and the canonical seesaw mechanism naturally generates small neutrino masses. The various possibilities from combining these two models are listed. Enough constraints are produced to narrow down the parameters of the neutrino mass matrix to two. This is therefore a predictive model, where the physical neutrino masses and the allowed regions for neutrinoless double beta decay are suggested.

We study the lepton flavor-violating processes in the simplest little Higgs model. First, we examine the constraints on the relevant parameters from the rare decays $l_i\to l_j\gamma$ ($i\ne j$ and $l_i=e,\mu ,\tau$), especially for the latest data of $Br(\mu \to e\gamma )$. Then, we calculate the lepton flavor-violating processes $e^{+}{e}^{-}\to l_i{\overline{l}}_j$ and $\gamma \gamma \to l_i{\overline{l}}_j$ at the International Linear Collider and find that the simplest little Higgs model can produce significant contributions to these processes. The rates of $\gamma \gamma \to l_i{\overline{l}}_j$ can reach $\mathcal{O}(1)\mathrm{fb}$ in the parameter space allowed by the experimental data, which implies that these processes may be observed at the International Linear Collider.

Following recent low-threshold analysis of the Sudbury Neutrino Observatory and asymmetry measurements of the BOREXINO Collaboration of the solar neutrino flux, we revisit the analysis of the matter effects in the Sun. We show that solar neutrino data constrains the mixing angle ${\theta }_{13}$ poorly and that subdominant Standard Model effects can mimic the effects of the physics beyond the Standard Model.

Coherent neutrino-nucleon scattering offers a unique approach in the search for physics beyond the standard model. When used in conjunction with monoenergetic neutrino sources, the technique can be sensitive to the existence of light sterile neutrinos. The ability to utilize such reactions has been limited in the past due to the extremely low-energy threshold (10–50 eV) needed for detection. In this paper, we discuss an optimization of cryogenic solid-state bolometers that enables reaching extremely low kinetic energy thresholds. We investigate the sensitivity of an array of such detectors to neutrino oscillations to sterile states. A recent analysis of available reactor data appears to favor the existence of such a sterile neutrino with a mass splitting of $|\Delta m_{\mathrm{sterile}}{|}^2\ge 1.5{\mathrm{eV}}^2$ and mixing strength of ${sin}^{2}2{\theta }_{\mathrm{sterile}}=0.17\pm 0.08$ at 95% confidence level. An array of such low-threshold detectors would be able to make a definitive statement as to the validity of the interpretation.

Perturbed Kerr black holes emit gravitational radiation, which (for the practical purposes of gravitational-wave astronomy) consists of a superposition of damped sinusoids termed quasinormal modes. The frequencies and time constants of the modes depend only on the mass and spin of the black hole—a consequence of the no-hair theorem. It has been proposed that a measurement of two or more quasinormal modes could be used to confirm that the source is a black hole and to test if general relativity continues to hold in ultrastrong gravitational fields. In this paper, we propose a practical approach to testing general relativity with quasinormal modes. We will also argue that the relative amplitudes of the various quasinormal modes encode important information about the origin of the perturbation that caused them. This helps in inferring the nature of the perturbation from an observation of the emitted quasinormal modes. In particular, we will show that the relative amplitudes of the different quasinormal modes emitted in the process of the merger of a pair of nonspinning black holes can be used to measure the component masses of the progenitor binary.

The phase transition of Reissner-Nordström black holes in ($n+1$)-dimensional anti–de Sitter spacetime is studied in detail using the thermodynamic analogy between a RN-AdS black hole and a van der Waals liquid-gas system. We first investigate critical phenomena of the RN-AdS black hole. The critical exponents of relevant thermodynamical quantities are evaluated. We find identical exponents for a RN-AdS black hole and a van der Waals liquid-gas system. This suggests a possible universality in the phase transitions of these systems. We finally study the thermodynamic behavior using the equilibrium thermodynamic state space geometry and find that the scalar curvature diverges exactly at the van der Waals–like critical point where the heat capacity at constant charge of the black hole diverges.

The existence of a minimal measurable length is a common feature of various approaches to quantum gravity such as string theory, loop quantum gravity, and black-hole physics. In this scenario, all commutation relations are modified and the Heisenberg uncertainty principle is changed to the so-called Generalized (Gravitational) Uncertainty Principle (GUP). Here, we present a one-dimensional nonperturbative approach to quantum mechanics with minimal length uncertainty relation which implies $X=x$ to all orders and $P=p+\frac{1}{3}\beta p^3$ to first order of GUP parameter $\beta$, where $X$ and $P$ are the generalized position and momentum operators and $[x,p]=i\hslash$. We show that this formalism is an equivalent representation of the seminal proposal by Kempf, Mangano, and Mann and predicts the same physics. However, this proposal reveals many significant aspects of the generalized uncertainty principle in a simple and comprehensive form and the existence of a maximal canonical momentum is manifest through this representation. The problems of the free particle and the harmonic oscillator are exactly solved in this GUP framework and the effects of GUP on the thermodynamics of these systems are also presented. Although $X$, $P$, and the Hamiltonian of the harmonic oscillator all are formally self-adjoint, the careful study of the domains of these operators shows that only the momentum operator remains self-adjoint in the presence of the minimal length uncertainty. We finally discuss the difficulties with the definition of potentials with infinitely sharp boundaries.

The anomalous conformal transformation law of the generalized entropy is found for dilaton gravity coupled to a $1+1$ conformal matter sector with central charges $c=\tilde{c}$. (When $c\ne \tilde{c}$ the generalized entropy is not invariant under local Lorentz boosts.) It is shown that a certain second null derivative of the entropy, $S_{\mathrm{gen}}^{\prime \prime }+(6/c)(S_{\mathrm{out}}^{\prime }{)}^2$, is primary, and therefore retains its sign under a general conformal transformation. Consequently, all conformal vacua have increasing entropy on causal horizons. Alternative definitions of the horizon, including apparent or dynamical horizons, can have decreasing entropy in any dimension $D\ge 2$. This indicates that the generalized second law should be defined using the causal horizon.

We generalize the perturbations theory of loop quantum cosmology to a hydrodynamical form and define an effective curvature perturbation on a uniform-density hypersurfaces ${\zeta }_e$. As in the classical cosmology, ${\zeta }_e$ should be gauge-invariant and conservative on the large scale. The evolutions of both the adiabatic and the nonadiabatic perturbations for a multifluid model are investigated in the framework of the effective hydrodynamical theory of loop quantum cosmology with the inverse-triad correction. We find that, different from the classical cosmology, the evolution of the large-scale nonadiabatic entropy perturbation can be driven by an adiabatic curvature perturbation and this adiabatic source for the nonadiabatic perturbation is a quantum effect. As an application of the related formalism, we study a decay model and give out the numerical results.

We analyze the flavor violation in warped extra dimension due to radion mediation. We show that $\Delta S=2$ and $\Delta B=2$ flavor violating processes impose stringent constraints on radion mass, $m_{\varphi }$ and the scale ${\Lambda }_{\varphi }$. In particular, for ${\Lambda }_{\varphi }\sim \mathcal{O}(1)\mathrm{TeV}$, $B_d^0-{\overline{B}}_d^0$ implies that $m_{\varphi }\gtrsim 65\mathrm{GeV}$. We also study radion contributions to lepton flavor violating processes: $\tau \to (e,\mu )\varphi$, $\tau \to e{\mu }^{+}{\mu }^{-}$ and $B\to l_i{l}_j$. We show that $\mathrm{BR}(B_s\to {\mu }^{+}{\mu }^{-})$ can be of order ${10}^{-8}$, which is reachable at the LHCb. The radion search at LHC, through the flavor violation decays into $\tau \mu$ or top-charm quarks, is also considered.