Beginning with a set of simplified models for spin-0, spin-$\frac{1}{2}$, and spin-1 dark matter candidates, we derive the full set of nonrelativistic operators and nuclear matrix elements relevant for direct detection of dark matter and use these to calculate rates and recoil spectra for scattering on various target nuclei. This allows us to explore what high energy physics constraints might be obtainable from direct detection experiments, what degeneracies exist, which operators are ubiquitous, and which are unlikely or subdominant. We find that there are operators which are common to all spins as well operators which are unique to spin-$\frac{1}{2}$ and spin-1 and elucidate two new operators which have not been previously considered. In addition we demonstrate how recoil energy spectra can distinguish fundamental microphysics if multiple target nuclei are used. Our work provides a complete road map for taking generic fundamental dark matter theories and calculating rates in direct detection experiments. This provides a useful guide for experimentalists designing experiments and theorists developing new dark matter models.

Using recent measurements of the spectrum and chemical composition of the highest energy cosmic rays, we consider the sources of these particles. We find that these data strongly prefer models in which the sources of the ultra-high-energy cosmic rays inject predominantly intermediate mass nuclei, with comparatively few protons or heavy nuclei, such as iron or silicon. If the number density of sources per comoving volume does not evolve with redshift, the injected spectrum must be very hard ($\alpha \simeq 1$) in order to fit the spectrum observed from Earth. Such a hard spectral index would be surprising and difficult to accommodate theoretically. In contrast, much softer spectral indices, consistent with the predictions of Fermi acceleration ($\alpha \simeq 2$), are favored in models with negative source evolution. With this theoretical bias, these observations thus favor models in which the sources of the highest energy cosmic rays are preferentially located within the low-redshift universe.

We investigate diboson signals in the standard model (SM) with an extended Higgs sector, motivated by the excesses in the diboson channels at the LHC. We begin with the unitarity sum rules of the weak gauge boson scattering assuming the Higgs sector is extended. According to the sum rules, we discuss the Higgs interpretations of the diboson signals and the consistency with the ATLAS diboson anomaly and other experimental constraints. As a concrete example, we propose a two-Higgs-doublet model where the Yukawa coupling of an extra $CP$-even scalar with up-type quark is relatively large. The diboson ($WW$ and $ZZ$) signals can be explained by 2 TeV $CP$-even Higgs boson, while the partners, the $CP$-odd and the charged Higgs bosons in the extra doublet, are severely constrained by both the LHC direct search and the indirect search via flavor observables. Especially, in order to avoid the diboson resonance search in the $Vh$ channel, further extensions of the model are required. The diboson excess is correlated with the SM Higgs signals in our framework, so that the precise measurement of the SM Higgs boson is also important to test the Higgs interpretation.

We calculate model-independently the impact of the critical point on higher-order baryon susceptibilities ${\chi }_n$, showing how they depend on fluctuations of the order parameter. We characterize the kurtosis of the order parameter fluctuations and the baryon moments ${\chi }_3,{\chi }_4$ as functions on the phase diagram. Important features of this analysis are then confirmed by a Gross–Neveu model study with good qualitative agreement with other model studies. We also compare this to lattice and experimental data. Our results support the universality of the characteristic peak in baryon susceptibilities as a signal of the critical point. We discuss leveraging measurements of different ${\chi }_n$ to extrapolate the location of the critical point.

The ratio of the measured $\overline{B}\to D^{(*)}\ell \overline{\nu }$ decay rates for $\ell =\tau$ vs $e,\mu$ deviate from the standard model (SM) by about $4\sigma$. We show that the data are in tension with the SM, independent of form factor calculations, and we update the SM prediction for $\mathcal{B}(B\to X_c\tau \overline{\nu })/\mathcal{B}(B\to X_c\ell \overline{\nu })$. We classify the operators that can accommodate the measured central values, as well as their UV completions. We identify models with leptoquark mediators that are minimally flavor violating in the quark sector, and are minimally flavor violating or $\tau$-aligned in the lepton sector. We explore experimental signatures of these scenarios, which are observable in the future at ATLAS/CMS, LHCb, or Belle II.

We have applied a microscopic model for single photon emission in neutral current interactions on nucleons and nuclei to determine the number and distributions of such events at the Super-Kamiokande detector, for the flux and beam exposure of the T2K experiment in neutrino mode. These reactions represent an effectively irreducible background in electron-(anti)neutrino appearance measurements aimed at a precise measurement of mixing angle ${\theta }_{13}$ and the $CP$ violating phase. We have obtained a total number of photon events that is twice as large as the one from the NEUT event generator (version 5.1.4.2) used in the analysis of T2K data. Detailed comparisons of energy and angular distributions for the ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ fluxes have also been performed.

We perform a preliminary study of the ability of the Higgs decay to four leptons to shed light on the top quark Yukawa couplings. In particular we examine whether the $h\to 4\ell$ “golden channel” is sensitive to the $CP$ properties of the top quark couplings to the Higgs boson. We show that kinematic distributions are sensitive to interference of the next-to-leading order electroweak corrections with the tree level $ZZ$ contribution. This translates into a sensitivity to the top quark Yukawa couplings such that meaningful constraints on their $CP$ properties can begin to be obtained once $\sim 300{\mathrm{fb}}^{-1}$ of data has been collected at $\sim 14\mathrm{TeV}$, with significant improvements at higher luminosity or with a higher energy hadron collider. This makes the $h\to 4\ell$ channel a useful probe of the top quark Yukawa couplings that is qualitatively different from already established searches in $h\to V\gamma$ two body decays, $tth$, and $gg\to h$. We also briefly discuss other potential possibilities for probing the top Yukawa $CP$ properties in $h\to 2\ell \gamma$ and ${\ell }^{+}{\ell }^{-}\to hZ,h\gamma$.

An amplitude analysis of the ${\pi }^0{\pi }^0$ system produced in radiative $J/\psi$ decays is presented. In particular, a piecewise function that describes the dynamics of the ${\pi }^0{\pi }^0$ system is determined as a function of $M_{{\pi }^0{\pi }^0}$ from an analysis of the $(1.311\pm 0.011)\times {10}^9$ $J/\psi$ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the ${\pi }^0{\pi }^0$ system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of $J/\psi \to \gamma {\pi }^0{\pi }^0$ is determined to be $(1.15\pm 0.05)\times {10}^{-3}$, where the uncertainty is systematic only and the statistical uncertainty is negligible.

Based on a sample of ${\eta }^{\prime }$ mesons produced in the radiative decay $J/\psi \to \gamma {\eta }^{\prime }$ in $1.31\times {10}^{9}J/\psi$ events collected with the BESIII detector, the decay ${\eta }^{\prime }\to \omega e^{+}{e}^{-}$ is observed for the first time, with a statistical significance of $8\sigma$. The branching fraction is measured to be $\mathcal{B}({\eta }^{\prime }\to \omega e^{+}{e}^{-})=(1.97\pm 0.34(\text{stat})\pm 0.17(\text{syst}))\times {10}^{-4}$, which is in agreement with theoretical predictions. The branching fraction of ${\eta }^{\prime }\to \omega \gamma$ is also measured to be $(2.55\pm 0.03(\text{stat})\pm 0.16(\text{syst}))\times {10}^{-2}$, which is the most precise measurement to date, and the relative branching fraction $\frac{\mathcal{B}({\eta }^{\prime }\to \omega e^{+}{e}^{-})}{\mathcal{B}({\eta }^{\prime }\to \omega \gamma )}$ is determined to be $(7.71\pm 1.34(\text{stat})\pm 0.54(\text{syst}))\times {10}^{-3}$.

In the present paper we study the behavior of the normalized $I\text{−}Q$ relation for neutron stars in a particular class of $f(R)$ theories of gravity, namely the $R^2$ gravity that is one of the most natural and simplest extensions of general relativity in the strong field regime. We study both the slowly and rapidly rotating cases. The results show that the $I\text{−}Q$ relation remains nearly equation of state independent for fixed values of the normalized rotational parameter, but the deviations from universality can be a little bit larger reaching roughly 3% compared to the general relativistic case where the deviations are of the order of 1%. What is the most interesting in our studies, is that the differences with the pure Einstein theory can be large reaching above 20%. This is qualitatively different from the majority of alternative theories of gravity, where the normalized $I\text{−}Q$ relations are almost indistinguishable from the general relativistic case, and can lead to observational constraints on $f(R)$ theories in the future.

The measured masses of the Higgs boson and top quark indicate that the effective potential of the standard model either develops an unstable electroweak vacuum or stands stable all the way up to the Planck scale. In the latter case in which the top quark mass is about $2\sigma$ below its present central value, the Higgs boson can be the inflaton with the help of a large nonminimal coupling to curvature in four dimensions. We propose a scenario in which the Higgs boson can be the inflaton in a five-dimensional Gauss-Bonnet braneworld model to solve both the unitarity and stability problems which usually plague Higgs inflation. We find that in order for Higgs inflation to happen successfully in the Gauss-Bonnet regime, the extra dimension scale must appear roughly in the range between the TeV scale and the instability scale of standard model. At the tree level, our model can give rise to a naturally small nonminimal coupling $\xi \sim \mathcal{O}(1)$ for the Higgs quartic coupling $\lambda \sim \mathcal{O}(0.1)$ if the extra dimension scale lies at the TeV scale. At the loop level, the inflationary predictions at the tree level are preserved. Our model can be confronted with future experiments and observations from both particle physics and cosmology.

We describe a method for sensing short range forces using matter-wave interference in dielectric nanospheres. When compared with atom interferometers, the larger mass of the nanosphere results in reduced wave-packet expansion, enabling investigations of forces nearer to surfaces in a free-fall interferometer. By laser cooling a nanosphere to the ground state of an optical potential and releasing it by turning off the optical trap, acceleration sensing at the ${10}^{-8}\mathrm{m}/{\mathrm{s}}^2$ level is possible. The approach can yield improved sensitivity to Yukawa-type deviations from Newtonian gravity at the $5\mu \mathrm{m}$ length scale by a factor of ${10}^4$ over current limits.

We present a new approach to the vacuum Bianchi IX model by combining affine coherent state quantization with Born-Oppenheimer-type adiabatic approximation in the analogy with quantum molecular physics. The analytical treatment is carried out on both quantum and semiclassical levels. Our quantization method by itself generates a specific repulsive potential that resolves the classical singularity. The quantized oscillatory degrees of freedom behave as radiation energy density. The Friedmann-like lowest-energy eigenstates of the system are found to be dynamically stable against small anisotropy perturbations, in contrast to the classical case.

We determine the couplings of the graviscalar radion in Randall-Sundrum models to Standard Model fields propagating in the bulk of the space, taking into account effects arising from the dynamics of the Goldberger-Wise scalar that stabilizes the size of the extra dimension. The leading corrections to the radion couplings are shown to arise from direct contact interactions between the Goldberger-Wise scalar and the Standard Model fields. We obtain a detailed interpretation of the results in terms of the holographic dual of the radion, the dilaton. In doing so, we determine how the familiar identification of the parameters on the two sides of the AdS/CFT correspondence is modified in the presence of couplings of the bulk Standard Model fields to the Goldberger-Wise scalar. We find that corrections to the form of the dilaton couplings from effects associated with the stabilization of the extra dimension are suppressed by the square of the ratio of the dilaton mass to the Kaluza-Klein scale, in good agreement with results from the CFT side of the correspondence.

With the discovery of the Higgs boson at the Large Hadron Collider the high energy physics community’s attention has now turned to understanding the properties of the Higgs boson, together with the hope of finding more scalars during run 2. In this work we discuss scenarios where using a combination of three decays, involving the 125 GeV Higgs boson, the $Z$ boson and at least one more scalar, an indisputable signal of $CP$-violation arises. We use a complex two-Higgs doublet model as a reference model and present some benchmark points that have passed all current experimental and theoretical constraints, and that have cross sections large enough to be probed during run 2.

We have investigated the electromagnetic decays of the antitriplet and sextet charmed baryon systems with $J^P={\frac{1}{2}}^{+},{\frac{3}{2}}^{+}$ in the framework of the heavy baryon chiral perturbation theory. We first construct the chiral Lagrangians at $O(p^2)$ and $O(p^3)$. Then we calculate the electromagnetic (EM) decay amplitudes of the charmed baryon systems up to $O(p^3)$. With the help of the quark model, we estimate the low energy constants. The numerical results of the EM decay widths show good convergence of the chiral expansion. We notice that the two neutral EM decay processes ${\mathrm{\Xi }}_c^{\prime 0}\to \gamma +{\mathrm{\Xi }}_c^0$ and ${\mathrm{\Xi }}_c^{*0}\to \gamma +{\mathrm{\Xi }}_c^0$ are strongly suppressed by the SU(3) U-spin flavor symmetry. With the same formalism, we also estimate the EM decay widths of the bottomed baryons. The EM decay widths of the heavy baryons may be measured at facilities such as LHCb and JPARC. The explicit chiral structures of the heavy baryon decay amplitudes derived in this work may be useful to the possible chiral extrapolations of the future lattice simulations of these EM decay amplitudes.

We present a unitary dispersive model for the $\eta \to 3\pi$ decay process based upon the Khuri-Treiman equations which are solved by means of the Pasquier inversion method. The description of the hadronic final-state interactions for the $\eta \to 3\pi$ decay is essential to reproduce the available data and to understand the existing discrepancies between Dalitz plot parameters from experiment and chiral perturbation theory. Our approach incorporates substraction constants that are fixed by fitting the recent high-statistics WASA-at-COSY data for $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$. Based on the parameters obtained, we predict the slope parameter for the neutral channel to be $\alpha =-0.022\pm 0.004$. Through matching to next-to-leading-order chiral perturbation theory, we estimate the quark mass double ratio to be $Q=21.4\pm 0.4$.

When a particle decays in an external field, the energy spectrum of the products is smeared. We derive an analytical expression for the shape function accounting for the motion of the decaying particle and the final state interactions. We apply our result to calculate the muonium decay spectrum and comment on applications to the muon bound in an atom.

We derive relativistic hydrodynamics from quantum field theories by assuming that the density operator is given by a local Gibbs distribution at initial time. We decompose the energy-momentum tensor and particle current into nondissipative and dissipative parts, and analyze their time evolution in detail. Performing the path-integral formulation of the local Gibbs distribution, we microscopically derive the generating functional for the nondissipative hydrodynamics. We also construct a basis to study dissipative corrections. In particular, we derive the first-order dissipative hydrodynamic equations without a choice of frame such as the Landau-Lifshitz or Eckart frame.