There exist several theoretical motivations for primordial correlation functions (such as the power spectrum) to contain oscillations as a logarithmic function of comoving momentum $k$. While these features are commonly searched for in $k$ space, an alternative is to use angular space, that is, search for correlations between the directional vectors of observation. We develop tools to efficiently compute the angular correlations based on a stationary phase approximation and examine several example oscillations in the primordial power spectrum, bispectrum, and trispectrum. We find that logarithmically periodic oscillations are essentially featureless and therefore difficult to detect using the standard correlator, though others might be feasible.

If long-wavelength primordial tensor modes are coupled to short-wavelength scalar modes, the scalar curvature two-point function will have an off-diagonal component. This “fossil” remnant is a signature of a mode coupling that cannot be achieved in single-clock inflation. Any constraint on its presence allows a cross-check of the relationship between the dynamical generation of the fluctuations and the evolution of the inflationary background. We use the example of non—Bunch-Davies initial states for the tensor and scalar modes to demonstrate that physically reasonable fossils, consistent with current data, can be observable in the near future. We illustrate how the fossil off-diagonal power spectrum is a complementary probe to the squeezed limit bispectra of the scalar and tensor sectors individually. We also quantify the relation between the observable signal and the squeezed limit bispectrum for a general scalar-scalar-fossil coupling and note the effect of superhorizon tensor modes on the anisotropy in scalar modes.

We present techniques for bridging the gap between idealized inverse covariance weighted quadratic estimation of 21 cm power spectra and the real-world challenges presented universally by interferometric observation. By carefully evaluating various estimators and adapting our techniques for large but incomplete data sets, we develop a robust power spectrum estimation framework that preserves the so-called "Epoch of Reionization (EoR) window" and keeps track of estimator errors and covariances. We apply our method to observations from the 32-tile prototype of the Murchinson Widefield Array to demonstrate the importance of a judicious analysis technique. Lastly, we apply our method to investigate the dependence of the clean EoR window on frequency—especially the frequency dependence of the so-called “wedge" feature—and establish upper limits on the power spectrum from $z=6.2$ to $z=11.7$. Our lowest limit is $\mathrm{\Delta }(k)<0.3$ Kelvin at 95% confidence at a comoving scale $k=0.046\mathrm{Mpc}{}^{-1}$ and $z=9.5$.

We propose a new paradigm for generating exponentially spread standard model Yukawa couplings from a new $U(1{)}_F$ gauge symmetry in the dark sector. Chiral symmetry is spontaneously broken among dark fermions that obtain nonvanishing masses from a nonperturbative solution to the mass gap equation. The necessary ingredient for this mechanism to work is the existence of higher-derivative terms in the dark $U(1{)}_F$ theory, or equivalently the existence of Lee–Wick ghosts, that (i) allow for a nonperturbative solution to the mass gap equation in the weak coupling regime of the Abelian theory and (ii) induce exponential dependence of the generated masses on dark fermion $U(1{)}_F$ quantum numbers. The generated flavor and chiral symmetry breaking in the dark sector is transferred to the standard model Yukawa couplings at the one-loop level via Higgs portal-type scalar messenger fields. The latter carry quantum numbers of squarks and sleptons. A new intriguing phenomenology is predicted that could be potentially tested at the LHC, provided the characteristic mass scale of the messenger sector is accessible at the LHC as is suggested by naturalness arguments.

Recently Weinberg suggested that Goldstone bosons arising from the spontaneous breakdown of some global hidden symmetries can interact weakly in the early Universe and account for a fraction of the effective number of neutrino species $N_{\text{eff}}$, which has been reported persistently $1\sigma$ away from its expected value of three. In this work, we study in some details a number of experimental constraints on this interesting idea based on the simplest possibility of a global $U(1)$, as studied by Weinberg. We work out the decay branching ratios of the associated light scalar field $\sigma$ and suggest a possible collider signature at the Large Hadron Collider. In some corners of the parameter space, the scalar field $\sigma$ can decay into a pair of pions with a branching ratio of order $O(1)\%$ while the rest is mostly a pair of Goldstone bosons. The collider signature would be gluon fusion into the standard model Higgs boson $gg\to H$ or associated production with a $W$ gauge boson $q{\overline{q}}^{\prime }\to HW$, followed by $H\to \sigma \sigma \to (\pi \pi )(\alpha \alpha )$ where $\alpha$ is the Goldstone boson.

We explore supersymmetry (SUSY) parameter space with nonuniversal high scale parameters in a gravity mediated SUSY breaking (SUGRA) scenario that accommodates a Higgs mass of $(125\pm 2)\mathrm{GeV}$ while satisfying cold dark matter relic density and other low energy constraints. We indicate a few benchmark points consistent with different dark matter annihilation processes where third family squarks are lighter than the first two as a requirement to keep the Higgs mass within the limit. We show that bottom rich and leptonic final states have a better reach in such parameter space points and is the most likely scenario to discover SUSY at the upcoming run of LHC with center-of-mass energy 14 TeV.

The scaling laws in an IR theory are dictated by the critical exponents of relevant operators. We have investigated these scaling laws at leading order in two previous papers. In this work we investigate further consequences of the scaling laws, trying to identify potential signatures that could be studied by lattice simulations. From the first derivative of the form factor we derive the behavior of the mean charge radius of the hadronic states in the theory. We obtain $⟨r_H^2⟩\sim m^{-2/(1+{\gamma }_m^{*})}$ which is consistent with $⟨r_H^2⟩\sim 1/M_H^2$. The mean charge radius can be used as an alternative observable to assess the size of the physical states, and hence finite size effects, in numerical simulations. Furthermore, we discuss the behavior of specific field correlators in coordinate space for the case of conformal, scale-invariant, and confining theories making use of selection rules in scaling dimensions and spin. We compute the scaling corrections to correlations functions by linearizing the renormalization group equations. We find that these corrections are potentially large close to the edge of the conformal window. As an application we compute the scaling correction to the formula $M_H\sim m^{1/(1+{\gamma }_m^{*})}$ directly through its associated correlator as well as through the trace anomaly. The two computations are shown to be equivalent through a generalization of the Feynman-Hellmann theorem for the fermion mass and the gauge coupling.

We study the possibility of detecting new physics (NP) phenomena at the LHC through a new search strategy looking at the monotop (top plus missing energy) signature which is common to a variety of NP models. We focus on the leptonic top decay mode and study the discovery or exclusion reach of the 2012 LHC data for three example models. Contrary to the hadronic mode, in this case the problematic QCD multijet background can be safely neglected. We find that the key kinematic variable to suppress most of the remaining SM backgrounds is the transverse mass of the charged lepton and missing energy. In fact, one could expect that the single-top production measurements already address the monotop signature in this mode. This is, however, not the case, because in the SM single-top production, the transverse mass has an end point determined by the $W$ mass, while the NP signals typically have an additional source of missing energy. We compare, under the same conditions, our monotop search strategy with existing single-top measurements and find a considerable improvement in the monotop signature reach.

In the framework of the littlest Higgs model with $T$ parity, we present complete calculations for the $A_H{q}_{-}-(q_{-}=u_{-},{\overline{u}}_{-},d_{-},{\overline{d}}_{-},c_{-},{\overline{c}}_{-},s_{-},{\overline{s}}_{-})$, associated production up to the QCD next-to-leading order (NLO) at the CERN Large Hadron Collider with subsequent pure weak decay of $T$-odd mirror quark. We apply the PROSPINO scheme to avoid the double-counting problem and to keep the convergence of the perturbative QCD description. The theoretical correlations between the integrated cross section and the factorization and renormalization scale, the global symmetry-breaking scale, and the Yukawa coupling parameter are studied separately. We also provide the kinematic distributions of the final decay products. Our numerical results show that the NLO QCD correction reduces the scale uncertainty and enhances the leading-order integrated cross section remarkably, with the $K$ factor varying in the range of 1.41–1.68 (1.58–1.89) as the increment of the global symmetry-breaking scale $f$ from 500 GeV to 1.5 TeV (1.1 TeV) at the $\sqrt{s}=14\mathrm{TeV}$ (8 TeV) LHC. We find that it is possible to select the signal events of the $A_H{q}_{-}$ production from its background by putting proper cuts on the final leading jet and missing energy.

The differential cross section and spin asymmetries for neutral pions produced within the intermediate pseudorapidity range $0.8<\eta <2.0$ in polarized proton-proton collisions at $\sqrt{s}=200\mathrm{GeV}$ are presented. Neutral pions were detected using the end cap electromagnetic calorimeter in the STAR detector at RHIC. The cross section was measured over a transverse momentum range of $5<p_T<16\mathrm{GeV}/c$ and is found to agree with a next-to-leading order perturbative QCD calculation. The longitudinal double-spin asymmetry $A_{LL}$ is measured in the same pseudorapidity range and spans a range of Bjorken-$x$ down to $x\approx 0.01$. The measured $A_{LL}$ is consistent with model predictions for varying degrees of gluon polarization. The parity-violating asymmetry $A_L$ is also measured and found to be consistent with zero. The transverse single-spin asymmetry $A_N$ is measured over a previously unexplored kinematic range in Feynman-$x$ and $p_T$. Such measurements may aid our understanding of the onset and kinematic dependence of the large asymmetries observed at more forward pseudorapidity ($\eta \approx 3$) and their underlying mechanisms. The $A_N$ results presented are consistent with a twist-3 model prediction of a small asymmetry over the present kinematic range.

We calculate the bosonic boundary state associated with a rotating and moving $\mathrm{D}p$-brane in the presence of the antisymmetric tensor field, a $U(1)$ gauge field and a tachyon field. Rotation and motion are in the brane volume. We reconstruct this boundary state via the group $PSL(2,R)$ to be applicable when the tachyon field is presented. This modified boundary state enables us to calculate the interaction amplitude between two parallel $\mathrm{D}p$-branes with rotation and motion. The long-range force of this interaction will be obtained. The boundary state also enables us to investigate the tachyon condensation on a rotating and moving $\mathrm{D}p$-brane.

We examine the high energy (Regge) limit of gravitational scattering using a Wilson line approach previously used in the context of non-Abelian gauge theories. Our aim is to clarify the nature of the Reggeization of the graviton and the interplay between this Reggeization and the so-called eikonal phase which determines the spectrum of gravitational bound states. Furthermore, we discuss finite corrections to this picture. Our results are of relevance to various supergravity theories, and also help to clarify the relationship between gauge and gravity theories.

The Lagrangian governing the dynamics of a compact binary system is explicitly computed in the post-Minkowskian approximation, and at any post-Newtonian order, by means of the effective field theory approach. This result is then specialized to the fifth post-Newtonian order and allows us to determine one formerly unknown coefficient of the energy expression for binary point masses on the circular orbit as a function of the orbital angular frequency.

We investigate the Teichmüller parameters for a Euclidean multiple Bañados-Teitelboim-Zanelli (BTZ) black hole spacetime. To induce a complex structure in the asymptotic boundary of such a spacetime, we consider the limit in which two black holes are at a large distance from each other. In this limit, we can approximately determine the period matrix ${\mathrm{\Omega }}_{ij}$ (i.e., the Teichmüller parameters) for the spacetime boundary by using a pinching parameter. The Teichmüller parameters are essential in describing the partition function for the boundary conformal field theory (CFT). We provide an interpretation of the partition function for the genus two extremal boundary CFT proposed by Gaiotto and Yin that it is relevant to double BTZ black hole spacetime.

An important and useful relation is known to hold in two specific MOND theories. It pertains to low-acceleration, isolated systems of pointlike masses, $m_p$, at positions ${\mathbf{r}}_p$, subject to gravitational forces ${\mathbf{F}}_p$. It reads $\sum _p{\mathbf{r}}_p·{\mathbf{F}}_p=-(2/3){(G{a}_0)}^{1/2}[{(\sum _p{m}_p)}^{3/2}-\sum _p{m}_p^{3/2}]$; $a_0$ is the MOND acceleration constant. Here I show that this relation holds in the nonrelativistic limit of any modified-gravity MOND theory. It follows from only the basic tenets of MOND, which include departure from standard dynamics at accelerations below $a_0$, and space-time scale invariance in the nonrelativistic, low-acceleration limit. This implies space-dilatation invariance of the static, gravitational-field equations, which, in turn, leads to the above point-mass virial relation. Thus, the various MOND predictions and tests based on this relation hold in any modified-gravity MOND theory. Since we do not know that any of the existing MOND theories point in the right direction, it is important to identify such predictions that hold in a much larger class of theories. Among these predictions are the MOND two-body force for arbitrary masses, and a general mass-velocity-dispersion relation of the form ${\sigma }^2=(2/3){(MG{a}_0)}^{1/2}[1-\sum _p{(m_p/M)}^{3/2}]$, where $M=\sum _p{m}_p$.

In a previous work we have exhibited a clear description of the quantum-to-classical transition of cosmological quantum fluctuations in the inflationary scenario using the de Broglie–Bohm quantum theory. These fluctuations are believed to seed the small inhomogeneities, which are then responsible for the formation of large scale structures. In this work we show that using the de Broglie–Bohm theory, it is also possible to describe the quantum-to-classical transition of primordial perturbations which takes place around a bouncing phase, even if the latter is caused by quantum effects due to the quantization of the background geometry.

Using recent simulation results, we provide the mass and speed spectrum of cosmic string loops. This is the quantity of primary interest for many phenomenological signatures of cosmic strings, and it can be accurately predicted using recently acquired detailed knowledge of the loop production function. We emphasize that gravitational smoothing of long strings plays a negligible role in determining the total number of existing loops. We derive a bound on the string tension imposed by recent constraints on the stochastic gravitational wave background from pulsar timing arrays, finding $G\mu \le 2.8\times {10}^{-9}$. We also provide a derivation of the Boltzmann equation for cosmic string loops in the language of differential forms.

We study the entrainment effect between superfluid neutrons and charge neutral fluid (called the proton fluid) which is made of protons and electrons in a neutron star interior within the two-fluid formalism and using a relativistic model where baryon-baryon interaction is mediated by the exchange of $\sigma$, $\omega$, and $\rho$ mesons. This model of strong interaction also includes scalar self-interactions. The entrainment matrix and entrainment parameter are calculated using the parameter sets of Glendenning (GL) and another non-linear (NL3) interaction. The inclusion of $\rho$ mesons strongly influences the entrainment parameter (${ϵ}_{\text{mom}}$) in a superfluid neutron star. The entrainment parameter is constant at the core and drops rapidly at the surface. It takes values within the physical range.

The equation of state (EOS), $w(z)$, is the most important parameter of dark energy. We reconstruct the evolution of this EOS in a model-independent way using the latest cosmic microwave background (CMB) data from Planck and other observations, such as type Ia supernovae, the baryonic acoustic oscillation measurements (SDSS, 6dF, BOSS, and WiggleZ), and the Hubble parameter value $H(z)$. The results show that the EOS is consistent with the cosmological constant at the $2\sigma$ confidence level, not preferring a dynamical dark energy. The uncorrelated EOS of dark energy constraints from Planck CMB data are much tighter than those from the WMAP 9-year CMB data.