We apply the Karhunen-Loéve methods to cosmic microwave background (CMB) data sets, and show that we can recover the input cosmology and obtain the marginalized likelihoods in $\mathrm{\Lambda }$ cold dark matter cosmologies in under a minute, much faster than Markov chain Monte Carlo methods. This is achieved by forming a linear combination of the power spectra at each multipole $l$, and solving a system of simultaneous equations such that the Fisher matrix is locally unchanged. Instead of carrying out a full likelihood evaluation over the whole parameter space, we need evaluate the likelihood only for the parameter of interest, with the data compression effectively marginalizing over all other parameters. The weighting vectors contain insight about the physical effects of the parameters on the CMB anisotropy power spectrum $C_l$. The shape and amplitude of these vectors give an intuitive feel for the physics of the CMB, the sensitivity of the observed spectrum to cosmological parameters, and the relative sensitivity of different experiments to cosmological parameters. We test this method on exact theory $C_l$ as well as on a Wilkinson Microwave Anisotropy Probe (WMAP)-like CMB data set generated from a random realization of a fiducial cosmology, comparing the compression results to those from a full likelihood analysis using CosmoMC. After showing that the method works, we apply it to the temperature power spectrum from the WMAP seven-year data release, and discuss the successes and limitations of our method as applied to a real data set.

We investigate a constraint on reheating followed by $\alpha$-attractor-type inflation (the E-model and T-model) from an observation of the spectral index $n_s$. When the energy density of the Universe is dominated by an energy component with the cosmic equation-of-state parameter $w_{\mathrm{re}}$ during reheating, its $e$-folding number $N_{\mathrm{re}}$ and the reheating temperature $T_{\mathrm{re}}$ are bounded depending on $w_{\mathrm{re}}$. When the reheating epoch consists of two phases—where the energy density of the Universe is dominated by uniform inflaton field oscillations in the first phase and by relativistic nonthermalized particles in the second phase—we find a constraint on the $e$-folding number of the first oscillation phase, $N_{\mathrm{sc}}$, depending on the parameters of the inflaton potential. For the simplest perturbative reheating scenario, we find the lower bound for a coupling constant of inflaton decay in the E-model and T-model depending on the model parameters. We also find a constraint on the $\alpha$ parameter, $\alpha \gtrsim 0.01$, for the T-model and E-model when we assume a broad resonance reheating scenario.

The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale invariant. It has been shown, however, that the low-multipole spectrum of the cosmic microwave background anisotropies may hint at the presence of some features in the shape of the scalar PPS, which could deviate from its canonical power-law form. We study the possible degeneracies of this nonstandard PPS with the active neutrino masses, the effective number of relativistic species, and a sterile neutrino or a thermal axion mass. The limits on these additional parameters are less constraining in a model with a nonstandard PPS when including only the temperature autocorrelation spectrum measurements in the data analyses. The inclusion of the polarization spectra noticeably helps in reducing the degeneracies, leading to results that typically show no deviation from the $\mathrm{\Lambda }\mathrm{CDM}$ model with a standard power-law PPS. These findings are robust against changes in the function describing the noncanonical PPS. Albeit current cosmological measurements seem to prefer the simple power-law PPS description, the statistical significance to rule out other possible parametrizations is still very poor. Future cosmological measurements are crucial to improve the present PPS uncertainties.

In many models incorporating the type-I seesaw mechanism, the right-handed neutrino ($N$) couples to heavy vector/scalar bosons and thereby has resonant pair production. It has barely received attention thus far; however, it may provide the best avenue to probe TeV scale $N$ without requiring anomalously large mixing between $N$ and the active neutrino ${\nu }_L$. In this paper we explore the discovery prospects of (mainly heavy) $N$ pair production at the 14 TeV LHC and future 100 TeV $pp$ collider, based on the three signatures: (1) trilepton from $N(\to \ell W_{\ell })N(\to \ell W_h)$ with $W_{\ell /h}$ being the leptonically/hadronically decaying $W$; (2) boosted di-Higgs boson plus ${\cancel{E}}_T$ from $N(\to {\nu }_{L}h)N(\to {\nu }_{L}h)$; (3) a single boosted Higgs boson with leptons and ${\cancel{E}}_T$ from $N(\to \ell W_{\ell })N(\to {\nu }_{L}h)$. At the 100 TeV collider, we also consider the situation when the Higgs boson is overboosted, thus losing its jet substructure. Interpreting our tentative results in the benchmark model, the local $B-L$ model, we find that the (multi-) TeV scale $N$ can be probed at the (100) 14 TeV colliders.

We present a minimal model that simultaneously accounts for neutrino masses and the origin of dark matter (DM) and where the electroweak phase transition is strong enough to allow for electroweak baryogenesis. The Standard Model is enlarged with a Majorana fermion, three generations of chiral fermion pairs, and a single complex scalar that plays a central role in DM production and phenomenology, neutrino masses, and the strength of the phase transition. All the new fields are singlets under the SM gauge group. Neutrino masses are generated via a new variant of the radiative inverse seesaw mechanism, where the required small mass term is generated via loops involving DM and no large hierarchy is assumed among the mass scales. The model offers all the advantage of low-scale neutrino mass models as well as a viable dark matter candidate that is testable with direct detection experiments.

The effect of chirality imbalance on the QCD phase diagram is studied within the two flavors Nambu-Jona-Lasinio model. We focus especially on the issues related to how the chiral chemical potential (${\mu }_5$) affects the phase diagram, and find the “chiral catalysis” as well as “inverse chiral catalysis” effects, which are analogous to the magnetic catalysis and inverse magnetic catalysis effects. Furthermore, our results are different from the existing chiral model calculations, namely, there is no ${\mathrm{CEP}}_5$ on the $T\text{−}{\mu }_5$ plane, since the whole phase transition is a crossover. In addition, with the introduction of the chiral chemical potential, various QCD susceptibilities and the corresponding critical exponents are also studied.

We perform the first, to our knowledge, classical-statistical real time lattice simulations of topological transitions in the nonequilibrium glasma of weakly coupled but highly occupied gauge fields created immediately after the collision of ultrarelativistic nuclei. Simplifying our description by employing SU(2) gauge fields, and neglecting their longitudinal expansion, we find that the rate of topological transitions is initially strongly enhanced relative to the thermal sphaleron transition rate and decays with time during the thermalization process. Qualitative features of the time dependence of this nonequilibrium transition rate can be understood when expressed in terms of the magnetic screening length, which we also extract nonperturbatively. A detailed investigation of autocorrelation functions of the Chern-Simons number ($N_{\mathrm{CS}}$) reveals non-Markovian features of the evolution distinct from previous simulations of non-Abelian plasmas in thermal equilibrium.

We report on a classification of supersymmetric solutions to 11D supergravity with $SO(2,2)\times SO(3)$ isometry, which are $\mathrm{AdS}/\mathrm{CFT}$ dual to 2D CFTs with $\mathcal{N}=(0,4)$ supersymmetry. We recover the Maldacena, Strominger, Witten near-horizon with small superconformal symmetry and identify a class of ${\mathrm{AdS}}_3\times S^2\times S^2\times C{Y}_2$ geometries with emergent large superconformal symmetry. This exhausts known compact geometries. Compactification of M-theory on $C{Y}_2$ results in a vacuum of 7D supergravity with large superconformal symmetry, providing a candidate near-horizon for an extremal black hole and a potential new setting to address microstates.

We consider a generalized two brane Randall-Sundrum model where the branes are endowed with nonzero cosmological constant. In this scenario, we re-examine the modulus stabilization mechanism and the nature of Kaluza-Klein (KK) graviton modes. Our result reveals that while the KK mode graviton masses may change significantly with the brane cosmological constant, the Goldberger-Wise stabilization mechanism, which assumes a negligible backreaction on the background metric, continues to hold even when the branes have a large cosmological constant. The possibility of having a global minimum for the modulus is also discussed. Our results also include an analysis for the radion mass in this nonflat brane scenario.

We investigate photon merging and splitting processes in inhomogeneous, slowly varying electromagnetic fields. Our study is based on the three-photon polarization tensor following from the Heisenberg-Euler effective action. We put special emphasis on deviations from the well-known constant field results, also revisiting the selection rules for these processes. In the context of high-intensity laser facilities, we analytically determine compact expressions for the number of merged/split photons as obtained in the focal spots of intense laser beams. For the parameter range of typical petawatt class laser systems as pump and probe, we provide estimates for the numbers of signal photons attainable in an actual experiment. The combination of frequency upshifting, polarization dependence and scattering off the inhomogeneities renders photon merging an ideal signature for the experimental exploration of nonlinear quantum vacuum properties.

The two- and three-point functions and the four-gluon vertex of three-dimensional Yang-Mills theory are calculated from their Dyson-Schwinger equations and the three-particle irreducible effective action. Within a self-contained truncation, various effects of truncating Dyson-Schwinger equations are studied. Estimates for the errors induced by truncations are derived from comparisons between results from different equations, comparisons with lattice results, and varying higher Green functions. The results indicate that the two-loop diagrams are important in the gluon propagator, where they are explicitly calculated, but not for the vertices. Furthermore, the influence of the four-gluon vertex on lower Green functions is found to be small.

The modeling of intrinsic noise in pulsar timing residual data is of crucial importance for gravitational wave detection and pulsar timing (astro)physics in general. The noise budget in pulsars is a collection of several well-studied effects including radiometer noise, pulse-phase jitter noise, dispersion measure variations, and low-frequency spin noise. However, as pulsar timing data continue to improve, nonstationary and non-power-law noise terms are beginning to manifest which are not well modeled by current noise analysis techniques. In this work, we use a transdimensional approach to model these nonstationary and non-power-law effects through the use of a wavelet basis and an interpolation-based adaptive spectral modeling. In both cases, the number of wavelets and the number of control points in the interpolated spectrum are free parameters that are constrained by the data and then marginalized over in the final inferences, thus fully incorporating our ignorance of the noise model. We show that these new methods outperform standard techniques when nonstationary and non-power-law noise is present. We also show that these methods return results consistent with the standard analyses when no such signals are present.

One simplified black hole model constructed from a semiclassical analysis of loop quantum gravity (LQG) is called the self-dual black hole. This black hole solution depends on a free dimensionless parameter $P$ known as the polymeric parameter and also on the $a_0$ area related to the minimum area gap of LQG. In the limit of $P$ and $a_0$ going to zero, the usual Schwarzschild solution is recovered. Here we investigate the quasinormal modes (QNMs) of massless scalar perturbations in the self-dual black hole background. We compute the QN frequencies using the sixth-order WKB approximation method and compare them with numerical solutions of the Regge-Wheeler equation. Our results show that, as the parameter $P$ grows, the real part of the QN frequencies suffers an initial increase and then starts to decrease while the magnitude of the imaginary one decreases for fixed area gap $a_0$. This particular feature means that the damping of scalar perturbations in the self-dual black hole spacetimes is slower, and the oscillations are faster or slower according to the value of $P$.

We investigate how dark energy properties impact the cosmological limits on the total mass of active neutrinos. We consider two typical, simple dark energy models (that have only one more additional parameter than $\mathrm{\Lambda }\mathrm{CDM}$), i.e., the $w\mathrm{CDM}$ model and the holographic dark energy (HDE) model, as examples, to make an analysis. In the cosmological fits, we use the Planck 2015 temperature and polarization data, in combination with other low-redshift observations, including the baryon acoustic oscillations, type Ia supernovae, and Hubble constant measurement, as well as the Planck lensing measurements. We find that, once dynamical dark energy is considered, the degeneracy between $\sum m_{\nu }$ and $H_0$ will be changed, i.e., in the $\mathrm{\Lambda }\mathrm{CDM}$ model, $\sum m_{\nu }$ is anticorrelated with $H_0$, but in the $w\mathrm{CDM}$ and HDE models, $\sum m_{\nu }$ becomes positively correlated with $H_0$. Compared to $\mathrm{\Lambda }\mathrm{CDM}$, in the $w\mathrm{CDM}$ model the limit on $\sum m_{\nu }$ becomes much looser, but in the HDE model the limit becomes much tighter. In the HDE model, we obtain $\sum m_{\nu }<0.113\mathrm{eV}$ (95% C.L.) with the combined data sets, which is perhaps the most stringent upper limit by far on neutrino mass. Thus, our result in the HDE model is nearly ready to diagnose the neutrino mass hierarchy with the current cosmological observations.

We generalize the soft-wall and hard-wall models to a light-front holographic QCD model with a generic dilaton profile. The effective potential induced by a higher power dilaton profile is interpreted as a stronger color confinement at long distance, and it gradually evolves to the hard-wall model when the power increases to infinity. As an application, we investigate the exotic meson states recently discovered in experiments in the generic soft-wall model with a higher power dilaton profile, and the results are in agreement with the spectra of the exotic mesons. Our calculation indicates a weaker interaction at short distance and a stronger interaction at large distance for the components in the exotic mesons. The generic dilaton profile deserves further scrutiny for understanding the strong interaction and for applications.

The measurement of the anomalous magnetic moment of the muon exhibits a long-standing discrepancy compared to the standard model prediction. In this paper, we concentrate on this issue in the framework of the $R$-parity violating minimal supersymmetric standard model. Such a scenario provides a substantial contribution to the anomalous magnetic moment of the muon while satisfying constraints from low energy experimental observables as well as the neutrino mass. In addition, we point out that the implication of such operators satisfying muon $g-2$ are immense from the perspective of the LHC experiment, leading to a spectacular four muon final state. We propose an analysis in this particular channel which might help to settle the debate of $R$-parity violation as a probable explanation for $(g-2{)}_{\mu }$.

I discuss “truncated” QCD studied recently by Glozman et al. through numerical simulations. For two flavors it was observed that truncation restores the full chiral $U(2)\times U(2)$ symmetry of the Lagrangian. Moreover, additional enhancement of the above symmetry connecting representations with distinct Lorentz spins was observed. I argue that the chiral symmetry restoration in a confining theory could entail emergent (extra) dynamical flavors which would show up in the spectrum of color-singlet particles, provided their mass $\ne 0$. As an example, I consider truncated QCD with a single massless Dirac quark. Assuming the validity of the above observations, I demonstrate how a dynamical $SU(2{)}_{\mathrm{fl}}$ symmetry could emerge for massive spin-1 mesons without contradicting general principles.

The peak of the heavy quark pair entropy at the deconfinement transition, observed in lattice QCD, suggests that the transition is effectively driven by the increase of the entropy of bound states. The growth of the entropy with the interquark distance leads to the emergent entropic force that induces dissociation of quarkonium states. Since the quark-gluon plasma around the transition point is a strongly coupled system, we use the gauge-gravity duality to study the entropy of heavy quarkonium and the real-time dynamics of its dissociation. In particular, we employ the improved holographic QCD model as a dual description of large $N_c$ Yang-Mills theory. Studying the dynamics of the fundamental string between the quarks placed on the boundary, we find that the entropy peaks at the transition point. We also study the real-time dynamics of the system by considering the holographic string falling in the black hole horizon where it equilibrates. In the vicinity of the deconfinement transition, the dissociation time is found to be less than a fermi, suggesting that the entropic destruction is the dominant dissociation mechanism in this temperature region.