We assume that the current state of the Universe can be described by the inert doublet model, containing two scalar doublets, one of which is responsible for electroweak-symmetry breaking and masses of particles and the second one having no couplings to fermions and being responsible for dark matter. We consider possible evolutions of the Universe to this state during cooling down of the Universe after inflation. We found that in the past the Universe could pass through phase states having no dark matter candidate. In the evolution via such states, in addition to a possible electroweak-symmetry breaking phase transition (second order), the Universe sustained one first-order phase transition or two phase transitions of the second order.

The gauge structure of the four-dimensional effective theory arising from a pure $S{U}_5(N)$ Yang-Mills theory in five dimensions compactified on the orbifold $S^1/Z_2$ is reexamined on the basis of Becchi-Rouet-Stora-Tyutin symmetry. In this context, the two scenarios that can arise are analyzed: if the gauge parameters propagate in the bulk, the excited Kaluza-Klein (KK) modes are gauge fields, but they are matter vector fields if these parameters are confined in the 3-brane. In the former case, it is shown that the four-dimensional theory is gauge invariant only if the compactification is carried out by using curvatures instead of gauge fields as fundamental objects. Then, it is shown that the four-dimensional theory is governed by two types of gauge transformations, one determined by the KK zero modes of the gauge parameters, ${\alpha }^{(0)a}$, and another by the excited KK modes, ${\alpha }^{(n)a}$. The Dirac method and the proper solution of the master equation in the context of the field-antifield formalism are employed to show that the theory is subject to first-class constraints. A gauge-fixing procedure to quantize the KK modes $A_{\mu }^{(n)a}$ that is covariant under the first type of gauge transformations, which embody the standard gauge transformations of $S{U}_4(N)$, is introduced through gauge-fixing functions transforming in the adjoint representation of this group. The ghost sector induced by these gauge-fixing functions is derived on the basis of the Becchi-Rouet-Stora-Tyutin formalism. The effective quantum Lagrangian that links the interactions between light physics (zero modes) and heavy physics (excited KK gauge modes) is presented. Concerning the radiative corrections of the excited KK modes on the light Green’s functions, the predictive character of this Lagrangian at the one-loop level is stressed. In the case of the gauge parameters confined to the 3-brane, the known result in the literature is reproduced with some minor variants, although it is emphasized that the exited KK modes are not gauge fields but matter fields that transform under the adjoint representation of $S{U}_4(N)$. The Dirac method is employed to show that this theory is subject to both first- and second-class constraints, which arise from the zero and excited KK modes, respectively.

We study the pair production of charged gauge bosons at the LHC in a noncommutative extension of the standard model. We use angular distributions in the decays of the gauge bosons to partially reconstruct polarized cross sections. We use this, together with $CP$ considerations, to construct more sensitive observables that allow us to separate space-time from space-space noncommutativities.

In the framework of the topcolor-assisted technicolor (TC2) models, we study the productions of a single top or bottom quark associated with a scalar in $\gamma$-$p$ collision, which proceed via the subprocesses $c\gamma \to t{\pi }_t^0$, $c\gamma \to t{h}_t^0$, and $c\gamma \to b{\pi }_t^{+}$ mediated by the anomalous top or bottom coupling $tc{\pi }_t^0$, $tc{h}_t^0$, and $bc{\pi }_t^{+}$. These productions, while extremely suppressed in the standard model, are found to be significantly enhanced in the large part of the TC2 parameter space; especially, the production via $c\gamma \to b{\pi }^{+}$ can have a cross section of 100 fb, which may be accessible and allow for a test of the TC2 models.

We study the LHC search prospects for a model in which the neutrinos obtain Dirac masses from couplings to a second Higgs doublet with tiny vacuum expectation value. The model contains a charged Higgs boson that decays to $\ell \nu$ with branching fractions controlled by the neutrino masses and mixing angles as measured in neutrino oscillation experiments. The most promising signal is electroweak production of $H^{+}{H}^{-}$ pairs with decays to $\ell {\ell }^{\prime }{p}_T^{\mathrm{miss}}$, where $\ell {\ell }^{\prime }=e^{+}{e}^{-}$, ${\mu }^{+}{\mu }^{-}$, and $e^{\pm }{\mu }^{\mp }$. We find that a cut on the kinematic variable $M_{T2}$ eliminates most of the $t\overline{t}$ and $W$-pair background. Depending on the neutrino mass spectrum and mixing angles, a 100 (300) GeV charged Higgs could be discovered at the LHC with as little as $8(24){\mathrm{fb}}^{-1}$ of integrated luminosity at 14 TeV $pp$ center-of-mass energy.

We investigate the critical behavior of the three-dimensional, three-state Potts model in presence of a negative external field $h$, i.e. disfavoring one of the three states. A genuine phase transition is present for all values of $|h|$, corresponding to the spontaneous breaking of a residual $Z_2$ symmetry. The transition is first/second-order, respectively, for small/large values of $|h|$, with a tricritical field $h_{\mathrm{tric}}$ separating the two regimes. We provide, using different and consistent approaches, a precise determination of $h_{\mathrm{tric}}$; we also compare with previous studies and discuss the relevance of our investigation to analogous studies of the QCD phase diagram in presence of an imaginary chemical potential.

A recent study of $D^0\to {\pi }^0{K}^{+}{K}^{-}$ and $D^0\to K_S{\pi }^{+}{\pi }^{-}$ describes a flavor-symmetric approach to calculate relative amplitudes and phases, for characteristic interferences between $D$ decays to a light pseudoscalar $P$ and a light vector $V$, on Dalitz plots for $D\to PPP$ decays. The flavor-symmetric approach used an earlier fit to $D\to PV$ decay rates and was found to agree fairly well with experiments for $D^0\to {\pi }^0{\pi }^{+}{\pi }^{-}$ but not as well for $D^0\to {\pi }^0{K}^{+}{K}^{-}$ and $D^0\to K_S{\pi }^{+}{\pi }^{-}$. The present work extends this investigation to include $D^0\to K^{-}{\pi }^{+}{\pi }^0$. We use an SU(3) flavor symmetry relationship between ratios of Cabibbo-favored (CF) $D\to PV$ amplitudes in $D^0\to K^{-}{\pi }^{+}{\pi }^0$ and ratios of singly-Cabibbo-suppressed (SCS) $D\to PV$ amplitudes in $D^0\to {\pi }^0{K}^{+}{K}^{-}$ and $D^0\to {\pi }^0{\pi }^{+}{\pi }^{-}$. We observe that experimental values for Dalitz plot cross ratios obey this relationship up to discrepancies noted previously. The need for an updated Dalitz plot analysis of $D^0\to K^{-}{\pi }^{+}{\pi }^0$ is emphasized.

We report the first measurement of the differential cross section for the process $\gamma \gamma \to \eta \eta$ in the kinematic range above the $\eta \eta$ threshold, $1.096\mathrm{GeV}<W<3.8\mathrm{GeV}$ over nearly the entire solid angle range, $|\cos {\theta }^{*}|\le 0.9$ or $\le 1.0$ depending on $W$, where $W$ and ${\theta }^{*}$ are the energy and $\eta$ scattering angle, respectively, in the $\gamma \gamma$ center-of-mass system. The results are based on a $393{\mathrm{fb}}^{-1}$ data sample collected with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. In the $W$ range $1.1–2.0\mathrm{GeV}/c^2$ we perform an analysis of resonance amplitudes for various partial waves, and at higher energy we compare the energy and the angular dependences of the cross section with predictions of theoretical models and extract contributions of the ${\chi }_{cJ}$ charmonia.

I present results for top quark production in hadronic collisions at LHC and Tevatron energies. The soft-gluon corrections to the differential cross section are resummed at next-to-next-to-leading-logarithm accuracy via the two-loop soft anomalous dimension matrices. Approximate next-to-next-to-leading-order differential and total cross sections are calculated. Detailed theoretical predictions are shown for the $t\overline{t}$ cross section and the top quark $p_T$ distribution at the Tevatron and the LHC.

In this work, we systematically study the interaction of $D^{*}$ and nucleon, which is stimulated by the observation of ${\Lambda }_c(2940{)}^{+}$ close to the threshold of $D^{*}p$. Our numerical result obtained by the dynamical investigation indicates the existence of the $D^{*}N$ systems with $J^P={\frac{1}{2}}^{\pm }$, ${\frac{3}{2}}^{\pm }$, which not only provides valuable information to understand the underlying structure of ${\Lambda }_c(2940{)}^{+}$ but also improves our knowledge of the interaction of $D^{*}$ and nucleon. Additionally, the bottom partners of the $D^{*}N$ systems are predicted, which might be as one of the tasks in LHCb experiment.

We show that ordinary and radiative muon capture impose stringent constraints on sterile neutrino properties. In particular, we consider a sterile neutrino with a mass between 40 and 80 MeV that has a large mixing with the muon neutrino and decays predominantly into a photon and light neutrinos due to a large transition magnetic moment. Such a model was suggested as a possible resolution to the puzzle presented by the results of the LSND, KARMEN, and MiniBooNE experiments [S. Gninenko, arXiv:1009.5536.]. We find that the scenario with the radiative decay to massless neutrinos is ruled out by measurements of the radiative muon capture rates at TRIUMF in the relevant mass range by a factor of a few in the squared mixing angle. These constraints are complementary to those imposed by the process of electromagnetic upscattering and deexcitation of beam neutrinos inside the neutrino detectors induced by a large transition magnetic moment. The latter provide stringent constraints on the size of the transitional magnetic moment between muon or electron neutrinos and $N$. We also show that further extension of the model with another massive neutrino in the final state of the radiative decay may be used to bypass the constraints derived in this work.

We report the first measurement of transverse single-spin asymmetries in $J/\psi$ production from transversely polarized $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$ with data taken by the PHENIX experiment in 2006 and 2008. The measurement was performed over the rapidity ranges $1.2<|y|<2.2$ and $|y|<0.35$ for transverse momenta up to $6\mathrm{GeV}/c$. $J/\psi$ production at the Relativistic Heavy Ion Collider is dominated by processes involving initial-state gluons, and transverse single-spin asymmetries of the $J/\psi$ can provide access to gluon dynamics within the nucleon. Such asymmetries may also shed light on the long-standing question in QCD of the $J/\psi$ production mechanism. Asymmetries were obtained as a function of $J/\psi$ transverse momentum and Feynman-$x$, with a value of $-0.086\pm {0.026}^{\mathrm{stat}}\pm {0.003}^{\mathrm{syst}}$ in the forward region. This result suggests possible nonzero trigluon correlation functions in transversely polarized protons and, if well defined in this reaction, a nonzero gluon Sivers distribution function.

This article describes a determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ from the decay $B^0\to D^{*-}{\ell }^{+}{\nu }_{\ell }$ using $711{\mathrm{fb}}^{-1}$ of Belle data collected near the ${\rm Y}(4S)$ resonance. We simultaneously measure the product of the form factor normalization $\mathcal{F}(1)$ and the matrix element $|V_{cb}|$ as well as the three parameters ${\rho }^2$, $R_1(1)$ and $R_2(1)$, which determine the form factors of this decay in the framework of the heavy quark effective theory. The results, based on about 120 000 reconstructed $B^0\to D^{*-}{\ell }^{+}{\nu }_{\ell }$ decays, are ${\rho }^2=1.214\pm 0.034\pm 0.009$, $R_1(1)=1.401\pm 0.034\pm 0.018$, $R_2(1)=0.864\pm 0.024\pm 0.008$ and $\mathcal{F}(1)|V_{cb}|=(34.6\pm 0.2\pm 1.0)\times {10}^{-3}$. The branching fraction of $B^0\to D^{*-}{\ell }^{+}{\nu }_{\ell }$ is measured at the same time; we obtain a value of $\mathcal{B}(B^0\to D^{*-}{\ell }^{+}{\nu }_{\ell })=(4.58\pm 0.03\pm 0.26)\%$. The errors correspond to the statistical and systematic uncertainties. These results give the most precise determination of the form factor parameters and $\mathcal{F}(1)|V_{cb}|$ to date. In addition, a direct, model-independent determination of the form factor shapes has been carried out.

We present the complete four-loop four-point amplitude in $\mathcal{N}=4$ super-Yang-Mills theory, for a general gauge group and general $D$-dimensional covariant kinematics, and including all nonplanar contributions. We use the method of maximal cuts—an efficient application of the unitarity method—to construct the result in terms of 50 four-loop integrals. We give graphical rules, valid in $D$ dimensions, for obtaining various nonplanar contributions from previously-determined terms. We examine the ultraviolet behavior of the amplitude near $D=11/2$. The nonplanar terms are as well-behaved in the ultraviolet as the planar terms. However, in the color decomposition of the three- and four-loop amplitude for an $SU(N_c)$ gauge group, the coefficients of the double-trace terms are better behaved in the ultraviolet than are the single-trace terms. The results from this paper were an important step toward obtaining the corresponding amplitude in $\mathcal{N}=8$ supergravity, which confirmed the existence of cancellations beyond those needed for ultraviolet finiteness at four loops in four dimensions. Evaluation of the loop integrals near $D=4$ would permit tests of recent conjectures and results concerning the infrared behavior of four-dimensional massless gauge theory.

We study dissipative effects due to inertial forces acting on matter fields confined to accelerated boundaries in $1+1$, $2+1$, and $3+1$ dimensions. These matter fields describe the internal degrees of freedom of “mirrors” and impose, on the surfaces where they are defined, boundary conditions on a fluctuating “vacuum” field. We construct different models, involving either scalar or Dirac matter fields coupled to a vacuum scalar field, and use effective action techniques to calculate the strength of dissipation. In the case of massless Dirac fields, the results could be used to describe the inertial forces on an accelerated graphene sheet.

We study the strange quark mass dependence of the tricritical point of the $U(3{)}_L\times U(3{)}_R$ linear sigma model in the chiral limit. Assuming that the tricritical point is at a large strange mass value, the strange sector as well as the $\eta -a_0$ sector decouples from the light degrees of freedom which determines the thermodynamics. By tracing this decoupling we arrive from the original $U(3{)}_L\times U(3{)}_R$ symmetric model, going through the $U(2{)}_L\times U(2{)}_R$ symmetric one, at the $SU(2{)}_L\times SU(2{)}_R$ linear sigma model. One-loop level beta functions for the running of the parameters in each of these models and tree-level matching of the coupling of these models performed at intermediate scales are used to determine the influence of the heavy sector on the parameters of the $SU(2{)}_L\times SU(2{)}_R$ linear sigma model. By investigating the thermodynamics of this latter model we identified the tricritical surface of the $U(3{)}_L\times U(3{)}_R$ linear sigma model in the chiral limit. To apply the results for QCD we used different scenarios for the $m_s$ and ${\mu }_q$ dependence of the effective model parameters, and then the ${\mu }_q^{\mathrm{TCP}}(m_s)$ function can be determined. Depending on the details, a curve bending upwards or downwards near ${\mu }_q=0$ can be obtained, while with explicit chemical potential dependence of the parameters the direction of the curve can change with $m_s$, too.

In this paper we apply to gravitational waves from nonspinning binary systems a recently introduced frequentist methodology to calculate analytically the error for a maximum likelihood estimate of physical parameters. While existing literature focuses on using the Cramer Rao Lower bound and Monte Carlo simulations, we use a power expansion of the bias and covariance in inverse powers of the signal to noise ratio. The use of higher order derivatives of the likelihood function in the expansions makes the prediction also sensitive to the secondary lobes of the maximum likelihood estimate probability distribution. We discuss conditions for validity of the Cramer Rao Lower bound and predict new features in regions of the parameter space currently not explored. For example, we see how the bias can become the most important contributor to the parameters’ errors for high mass systems ($200M_{\odot }$ and above).

The article provides ready-to-use first post-Newtonian-accurate frequency-domain gravitational wave forms for eccentric nonspinning compact binaries of arbitrary mass ratio including the first post-Newtonian point particle corrections to the far-zone gravitational wave amplitude, given in terms of tensor-spherical harmonics. The averaged equations for the decay of the eccentricity and growth of radial frequency due to radiation reaction are used to provide stationary phase approximations to the frequency-domain wave forms.

We study cosmological vector and tensor perturbations in Horava-Lifshitz gravity, adopting the most general Sotiriou-Visser-Weinfurtner generalization without the detailed balance but with projectability condition. After deriving the general formulas in a flat Friedmann-Robertson-Walker (FRW) background, we find that the vector perturbations are identical to those given in general relativity. This is true also in the nonflat cases. For the tensor perturbations, high order derivatives of the curvatures produce effectively an anisotropic stress, which could have significant efforts on the high-frequency modes of gravitational waves, while for the low-frequency modes, the efforts are negligible. The power spectrum is scale-invariant in the UV regime, because of the particular dispersion relations. But, due to lower-order corrections, it will eventually reduce to that given in general relativity (GR) in the IR limit. Applying the general formulas to the de Sitter and power-law backgrounds, we calculate the power spectrum and index, using the uniform approximations, and obtain their analytical expressions in both cases.

Hints on the possible localization of fermions on double thick $D$-branes (domain walls) are found by analyzing the moduli space of parameters. Deeper analysis in this direction might help to select phenomenologically plausible models. A new kind of condition for fermion localization is proposed. This might be useful in multibrane world scenarios, which are important when symmetry breaking is considered in the AdS/CFT formalism, as well as in curved braneworlds.