We study the phenomenology of the type-II seesaw model at a linear $e^{-}{e}^{-}$ collider. We show that the process $e^{-}{e}^{-}\to {\alpha }^{-}{\beta }^{-}$ ($\alpha$, $\beta =e$, $\mu$, $\tau$ being charged leptons) mediated by a doubly charged scalar is very sensitive to the neutrino parameters, in particular, the absolute neutrino mass scale and the Majorana $CP$-violating phases. We identify the regions in parameter space in which appreciable collider signatures in the channel with two like-sign muons in the final state are possible. This includes Higgs triplet masses beyond the reach of the LHC.

We derive a holographic dual description of free quantum field theory in arbitrary dimensions, by reinterpreting the exact renormalization group to obtain a higher spin gravity theory of the general type which had been proposed and studied as a dual theory. We show that the dual theory reproduces all correlation functions.

Trajectories of light rays in a static spacetime are described by unparametrized geodesics of the Riemannian optical metric associated with the Lorentzian spacetime metric. We investigate the uniqueness of this structure and demonstrate that two different observers, moving relative to one another, who both see the Universe as static may determine the geometry of the light rays differently. More specifically, we classify Lorentzian metrics admitting more than one hyper-surface orthogonal timelike Killing vector and analyze the projective equivalence of the resulting optical metrics. These metrics are shown to be projectively equivalent up to diffeomorphism if the static Killing vectors generate a group $SL(2,\mathbb{R})$, but not projectively equivalent in general. We also consider the cosmological $C$ metrics in Einstein-Maxwell theory and demonstrate that optical metrics corresponding to different values of the cosmological constant are projectively equivalent.

Screening correlators and masses were studied at finite temperature in QCD with two flavors of dynamical staggered quarks on a lattice. The spectrum of screening masses show a hierarchical approach to chiral symmetry restoration. Control of explicit chiral symmetry breaking through the quark mass was shown to be an important step toward understanding this phenomenon. No sign of decay was found in the finite temperature scalar mesonlike correlators in the confined phase.

We compute the next-to-leading order QCD corrections to the polarized (and unpolarized) cross sections for the production of a hadron accompanied by an opposite-side prompt photon. This process, being studied at RHIC, permits us to reconstruct partonic kinematics using experimentally measurable variables. We study the correlation between the reconstructed momentum fractions and the true partonic ones, which in the polarized case might allow us to reveal the spin-dependent gluon distribution with a higher precision.

We analyze local models at the point of $E_8$ in $F$-theory grand unified theories and identify exactly two models with potentially realistic properties concerning proton stability and a suitable pattern of quark and lepton masses. To this end, we identify a matter parity at the local point. A globally consistent ultraviolet completion turns out to be problematic for both models. It is impossible to embed the models in a semilocal scheme via the spectral cover approach. This seems to severely limit the predictive power of local model building and to indicate that the full string theory might give us valuable hints for particle physics model building.

We investigate how gravity affects “Q-balls” with the Affleck-Dine potential $V_{\mathrm{AD}}(\varphi )≔\frac{m^2}{2}{\varphi }^2[1+K\ln (\frac{\varphi }{M}{)}^2]$. Contrary to the flat case, in which equilibrium solutions exist only if $K<0$, we find three types of gravitating solutions as follows. In the case that $K<0$, ordinary Q-ball solutions exist; there is an upper bound of the charge due to gravity. In the case that $K=0$, equilibrium solutions called (mini-)boson stars appear due to gravity; there is an upper bound of the charge, too. In the case that $K>0$, equilibrium solutions appear, too. In this case, these solutions are not asymptotically flat but surrounded by Q-matter. These solutions might be important in considering a dark matter scenario in the Affleck-Dine mechanism.

Proposed space-based gravitational-wave detectors such as BBO and DECIGO can detect $\sim {10}^6$ neutron star (NS) binaries and determine the luminosity distance to the binaries with high precision. Combining the luminosity distance and electromagnetically derived redshift, one would be able to probe cosmological expansion out to high redshift. In this paper, we show that the Hubble parameter as a function of redshift can be directly measured with monopole and dipole components of the luminosity distance on the sky. As a result, the measurement accuracies of the Hubble parameter in each redshift bin up to $z=1$ are 3–14%, 1.5–8%, and 0.8–4% for the observation time 1 yr, 3 yr, and 10 yr, respectively.

Determining the energy scale of inflation is crucial to understand the nature of inflation in the early universe. Assuming a power-law power spectrum of primordial curvature perturbations, we place observational constraints on the energy scale of the observable part of the inflaton potential by combining the 7-year Wilkinson Microwave Anisotropy Probe data with distance measurements from the baryon acoustic oscillations in the distribution of galaxies and the Hubble constant measurement. Our analysis provides an upper limit on this energy scale, $2.3\times {10}^{16}\mathrm{GeV}$ at 95% confidence level. Moreover, we forecast the sensitivity and constraints achievable by the Planck experiment by performing Monte Carlo studies on simulated data. Planck could significantly improve the constraints on the energy scale of inflation and on the shape of the inflaton potential.

Statistical isotropy is often assumed in cosmology and should be tested rigorously against observational data. We construct simple quadratic estimators to reconstruct asymmetry in the primordial power spectrum from CMB temperature and polarization data and verify their accuracy using simulations with quadrupole power asymmetry. We show that the Planck mission, with its millions of signal-dominated modes of the temperature anisotropy, should be able to constrain the amplitude of any spherical multipole of a scale-invariant quadrupole asymmetry at the 0.01 level ($2\sigma$). Almost independent constraints can be obtained from polarization at the 0.03 level after four full-sky surveys, providing an important consistency test. If the amplitude of the asymmetry is large enough, constraining its scale dependence should become possible. In scale-free quadrupole models with 1% asymmetry, consistent with the current limits from WMAP temperature data (after correction for beam asymmetries), Planck should constrain the spectral index $q$ of power-law departures from asymmetry to $\Delta q=0.3$. Finally, we show how to constrain models with axisymmetry in the same framework. For scale-free quadrupole models, Planck should constrain the direction of the asymmetry to a $1\sigma$ accuracy of about 2 degrees using one year of temperature data.

The walking technicolor theory attempts to realize electroweak symmetry breaking as the spontaneous chiral symmetry breakdown caused by the gauge dynamics with slowly varying gauge coupling constant and large mass anomalous dimension. Many-flavor QCD theories are candidates owning these features. We focus on the SU(3) gauge theory with ten flavors of massless fermions in the fundamental representation, and compute the gauge coupling constant in the Schrödinger functional scheme. Numerical simulation is performed with $O(a)$-unimproved lattice action, and the continuum limit is taken in linear in lattice spacing. We observe evidence that this theory possesses an infrared fixed point.

We give a factorization formula for the $e^{+}{e}^{-}$ thrust distribution $d\sigma /d\tau$ with $\tau =1-T$ based on the soft-collinear effective theory. The result is applicable for all $\tau$, i.e. in the peak, tail, and far-tail regions. The formula includes $\mathcal{O}({\alpha }_s^3)$ fixed-order QCD results, resummation of singular partonic ${\alpha }_s^j{ln}^k(\tau )/\tau$ terms with ${\mathrm{N}}^3\mathrm{LL}$ accuracy, hadronization effects from fitting a universal nonperturbative soft function defined with field theory, bottom quark mass effects, QED corrections, and the dominant top mass dependent terms from the axial anomaly. We do not rely on Monte Carlo generators to determine nonperturbative effects since they are not compatible with higher order perturbative analyses. Instead our treatment is based on fitting nonperturbative matrix elements in field theory, which are moments ${\Omega }_i$ of a nonperturbative soft function. We present a global analysis of all available thrust data measured at center-of-mass energies $Q=35–207\mathrm{GeV}$ in the tail region, where a two-parameter fit to ${\alpha }_s(m_Z)$ and the first moment ${\Omega }_1$ suffices. We use a short-distance scheme to define ${\Omega }_1$, called the $R$-gap scheme, thus ensuring that the perturbative $d\sigma /d\tau$ does not suffer from an $\mathcal{O}({\Lambda }_{\mathrm{QCD}})$ renormalon ambiguity. We find ${\alpha }_s(m_Z)=0.1135\pm (0.0002{)}_{\mathrm{expt}}\pm (0.0005{)}_{\mathrm{hadr}}\pm (0.0009{)}_{\mathrm{pert}}$, with ${\chi }^2/\mathrm{dof}=0.91$, where the displayed 1-sigma errors are the total experimental error, the hadronization uncertainty, and the perturbative theory uncertainty, respectively. The hadronization uncertainty in ${\alpha }_s$ is significantly decreased compared to earlier analyses by our two-parameter fit, which determines ${\Omega }_1=0.323\mathrm{GeV}$ with 16% uncertainty.

We present compact analytic expressions for all one-loop helicity amplitudes contributing to $t\overline{t}$ production at hadron colliders. Using recently developed generalized unitarity methods and a traditional Feynman based approach we produce a fast and flexible implementation.

Non-Abelian strings exist in the color-flavor locked phase of dense QCD. We show that kinks appearing in the world-sheet theory on these strings, in the form of the kink-antikink bound pairs, are the magnetic monopoles—descendants of the ’t Hooft–Polyakov monopoles surviving in such a special form in dense QCD. Our consideration is heavily based on analogies and inspiration coming from certain supersymmetric non-Abelian theories. This is the first ever analytic demonstration that objects unambiguously identifiable as the magnetic monopoles are native to non-Abelian Yang–Mills theories (albeit our analysis extends only to the phase of the monopole confinement and has nothing to say about their condensation). Technically, our demonstration becomes possible due to the fact that low-energy dynamics of the non-Abelian strings in dense QCD is that of the orientational zero modes. It is described by an effective two-dimensional $CP(2)$ model on the string world sheet. The kinks in this model representing confined magnetic monopoles are in a highly quantum regime.

A four-dimensional asymptotic expansion scheme is used to study the next-order effects of the nonlinearity near a spinning dynamical black hole. The angular-momentum flux and energy flux formula are then obtained by constructing the reference frame in terms of the compatible constant spinors and the compatibility of the coupling leading-order Newman-Penrose equations. By using the slow rotation and small-tide approximation for a spinning black hole, the horizon cross-section we chose is spherical symmetric. It turns out the flux formula is rather simple and can be compared with the known results. Directly from the energy flux formula of the slow-rotating dynamical horizon, we find that the physically reasonable condition on requiring the positivity of the gravitational energy flux yields that the shear will monotonically decrease with time. Thus a slow-rotating dynamical horizon will asymptotically approach an isolated horizon during late time.

We perform a consistent calculation of primordial black hole (PBH) mass spectrum and second-order induced gravitational wave (GW) background produced from primordial scalar perturbations in radiation era of the early Universe. It is shown that the maximal amplitudes of the second-order GW spectrum that can be approached without conflicting with the PBH data do not depend significantly on the shape of primordial perturbation spectrum. The constraints on the GW background obtained in previous works are extended to a wider GW frequency range. We discuss the applicability of the currently available pulsar timing limits for obtaining the constraints on scalar power spectrum and PBH abundance and show that they can be used for strongly constraining the PBH number density in the PBH mass range $\sim (0.03-10)M_{\odot }$.

We study theoretical constraints on the parameter space under the conditions from vacuum stability and triviality in the three-loop radiative seesaw model with TeV-scale right-handed neutrinos which are odd under the $Z_2$ parity. In this model, some of the neutrino Yukawa coupling constants can be of the order of 1. The requirement of a strongly first order phase transition for successful electroweak baryogenesis also prefers order-one coupling constants in the scalar sector. Hence, it is important to clarify whether this model satisfies those theoretical conditions up to a given cutoff scale. It is found that the model can be consistent up to the scale above 10 TeV in the parameter region where the neutrino data, the lepton-flavor violation data, the thermal relic abundance of dark matter as well as the requirement from the strongly first order phase transition are satisfied.

We propose a spectrum for a class of gauged noncompact $G/Ad(H)$ Wess-Zumino-Novikov-Witten models, including spectrally flowed images of highest, lowest, and mixed extremal weight modules. These are combined into blocks whose characters, due to the Lorentzian signature of the target space, are divergent and treated as formal expressions in need of regularization. Assuming that this is possible, we show that these extended characters transform linearly under modular transformations, and can be used to write down modular invariant partition functions.

The Skyrme-Faddeev model is a ($3+1$)-dimensional model which has knotted, stringlike, soliton solutions. In this paper we investigate a Skyrme-Faddeev model with an $SO(3)$ symmetry breaking potential. We then rescale this model and take the mass to infinity. This infinite mass model is found to have compact knotted solutions. In all of the investigated massive models we find similar charged solutions as in the usual $m=0$, model. We also find that their energies follow a similar $E\sim Q^{3/4}$ power growth as the $m=0$ model.

We introduce two ansatzs for the 3-form potential of Euclidean $11d$ supergravity on skew-whiffed ${\mathrm{AdS}}_4\times S^7$ background which results in two scalar modes with $m^2=-2$ on ${\mathrm{AdS}}_4$. Being conformally coupled with a quartic interaction, it is possible to find the exact solutions of the scalar equation on this background. These modes turn out to be invariant under the $SU(4)$ subgroup of the $SO(8)$ isometry group, whereas there are no corresponding $SU(4)$ singlet Bogomol’nyi-Prasad-Sommerfeld operators of dimensions one or two on the boundary theory constructed by Aharony, Bergman, Jafferis, and Maldacena. Noticing the interchange of ${\mathbf{8}}_s$ and ${\mathbf{8}}_c$ representations under skew-whiffing in the bulk, we propose the theory of antimembranes should similarly be obtained from Aharony, Bergman, Jafferis, and Maldacena’s theory by swapping these representations. In particular, this enables us to identify the dual boundary operators of the two scalar modes. We deform the boundary theory by the dual operators and examine the fermionic field equations, and compare the solutions of the deformed theory with those of the bulk.