Clustering of large-scale structure provides significant cosmological information through the power spectrum of density perturbations. Additional information can be gained from higher-order statistics like the bispectrum, especially to break the degeneracy between the linear halo bias $b_1$ and the amplitude of fluctuations ${\sigma }_8$. We propose new simple, computationally inexpensive bispectrum statistics that are near optimal for the specific applications like bias determination. Corresponding to the Legendre decomposition of nonlinear halo bias and gravitational coupling at second order, these statistics are given by the cross-spectra of the density with three quadratic fields: the squared density, a tidal term, and a shift term. For halos and galaxies the first two have associated nonlinear bias terms $b_2$ and $b_{s^2}$, respectively, while the shift term has none in the absence of velocity bias (valid in the $k\to 0$ limit). Thus the linear bias $b_1$ is best determined by the shift cross-spectrum, while the squared density and tidal cross-spectra mostly tighten constraints on $b_2$ and $b_{s^2}$ once $b_1$ is known. Since the form of the cross-spectra is derived from optimal maximum-likelihood estimation, they contain the full bispectrum information on bias parameters. Perturbative analytical predictions for their expectation values and covariances agree with simulations on large scales, $k\lesssim 0.09h/\mathrm{Mpc}$ at $z=0.55$ with Gaussian $R=20h^{-1}\mathrm{Mpc}$ smoothing, for matter-matter-matter, and matter-matter-halo combinations. For halo-halo-halo cross-spectra the model also needs to include corrections to the Poisson stochasticity.

We match the density of energy eigenstates of a local field theory with that of a random Hamiltonian order by order in a Taylor expansion. In our previous work we assumed Lorentz symmetry of the field theory, which entered through the dispersion relation. Here we extend that work to consider a generalized dispersion relation and show that the Lorentz symmetric case is preferred, in that the Lorentz symmetric dispersion relation give a better approximation to a random Hamiltonian than the other local dispersion relations we considered.

It is demonstrated that the complex Langevin method can simulate chiral random matrix theory at nonzero chemical potential. The successful match with the analytic prediction for the chiral condensate is established through a shift of matrix integration variables and choosing a polar representation for the new matrix elements before complexification. Furthermore, we test the proposal to work with a Langevin-time-dependent quark mass and find that it allows us to control the fluctuations of the phase of the fermion determinant throughout the Langevin trajectory.

We study dark matter at the MSSM pseudoscalar Higgs resonance (A funnel), which is one of the few remaining MSSM thermal dark matter candidates in the 100–1000 GeV range safe from direct detection constraints. To illustrate the various factors at play, this study is performed in two contrasting setups: a bottom-up phenomenological MSSM (pMSSM) approach that allows significant freedom and the top-down, highly constrained Yukawa unified $SO(10)$ GUT model. In the pMSSM, for $\mu >0$, the entire parameter space lies above the coherent neutrino background and mostly within reach of XENON1T and LZ, while blind spots exist at $m_A>800\mathrm{GeV}$ for $\mu <0$; the strongest constraints come from $A/H\to \tau \tau$ searches at the LHC. For Yukawa unified models, the confluence of $B_s\to {\mu }^{+}{\mu }^{-}$ constraints, fits to the bottom quark and Higgs masses, and gluino mass bounds from the LHC result in a prediction: realizing the pseudoscalar resonance requires gaugino mass nonuniversality, with a mass ratio that is determined to within a small range.

The reported excess of $\gamma$ rays, emitted from an extended region around the galactic center, has a distribution and rate suggestive of an origin in dark matter (DM) annihilations. The conventional annihilation channels into standard model (SM) $b$ quarks or $\tau$ leptons may, however, be in tension with various experimental constraints on antiproton and positron fluxes. We present a framework that is free from such constraints. The key idea is that the mediators between the dark matter and the SM are themselves part of a strongly coupled sector: a hidden valley. In this scenario, the dark matter particles annihilate only into hidden quarks that subsequently shower and hadronize. Hidden quark effective couplings to SM hypercharge allow the lightest hidden bound states to subsequently decay into SM photons, producing the observed photon energy spectrum. Associated production of SM fermions is, in contrast, suppressed by electroweak, loop or helicity effects. We find that, generically, $\sim 10\mathrm{GeV}$ DM and a confinement scale $\sim 1\mathrm{GeV}$ provide a good fit to the observed spectrum. An SU(2) hidden confining group is preferred over SU(3) or higher-rank gauge groups, up to uncertainties in the extraction of the astrophysical background. An explicit realization of this framework is also presented, and its phenomenology is discussed in detail, along with pertinent cosmological, astrophysical and collider bounds. This framework may be probed by model-independent searches, including future beam-dump experiments.

We show that the spectrum of the Dirac operator in complex Langevin simulations of QCD at nonzero chemical potential must behave in a way which is radically different from the one in simulations with ordinary noncomplexified gauge fields: at low temperatures the small eigenvalues of the Dirac operator must be inside the quark mass for chemical potentials as large as a third of the nucleon mass. In particular, in the chiral limit the Dirac eigenvalues of complex Langevin simulations must accumulate at the origin.

We discuss the properties of hadronic systems containing one heavy quark in the heavy quark limit. The heavy quark symmetry guarantees the mass degeneracy of the states with total spin and parity $(j-1/2{)}^P$ and $(j+1/2{)}^P$ with $j\ge 1/2$, because the heavy quark spin is decoupled from the total spin $j$ of the light components called brown muck. We apply this idea to heavy multihadron systems and formulate the general framework to analyze their properties. We demonstrate explicitly the spin degeneracy and the decomposition of the wave functions in exotic heavy hadron systems generated by the one-boson-exchange potential. The masses of the brown muck can be extracted from theoretical and experimental hadron spectra, leading to the color nonsinglet spectroscopy.

We calculate the next-to-leading order (NLO) quantum chromodynamics (QCD) corrections to the inclusive process of $Z_0\to B_c^{*}+\overline{c}+b$ under the nonrelativistic QCD (NRQCD) factorization scheme. Technical details about contributions from vector and axial-vector currents in a dimensional regularization scheme are discussed. Numerical calculation shows that the NLO correction enhances the leading-order decay width by about 50%, and the dependence on renormalization scale $\mu$ is reduced. The uncertainties induced by quark masses and the renormalization scale $\mu$ are also analyzed.

It has been shown previously [S. V. Troitsky and V. E. Troitsky, Phys. Rev. D 88, 093005 (2013)] that a nonperturbative relativistic constituent-quark model for the $\pi$-meson electromagnetic form factor allows for a quantitative description of the soft/hard transition, resulting in the correct quantum-chromodynamical asymptotics, including normalization, from the low-energy data without further parameter tuning. This happens universally whenever the constituent-quark mass is switched off. The energy range where the transition happens is therefore determined by the quark-mass running at intermediate energies and is not tightly constrained theoretically. Here we consider possible ways to pin down this energy range with coming experimental data. We demonstrate that expected experimental uncertainties of the 12 GeV Jefferson Lab data are larger than the span of predictions of the model, so these data might be used for testing the model but not for determination of the soft/hard transition scale. Contrarily, the projected electron-ion collider will be capable of pinning down the scale.

We study the lepton flavor violation in the supersymmetric seesaw model, taking into account recent experimental improvements, especially for the Higgs boson mass measurement, direct searches of superpartners, and the rare decay of $B_s\to {\mu }^{+}{\mu }^{-}$ at the LHC; the neutrino mixing angle of ${\theta }_{13}$ in the neutrino experiments; and the search of $\mu \to e\gamma$ in the MEG experiment. We obtain the latest constraints on the parameters in the supersymmetry-breaking terms and study the effect on the lepton-flavor-violating decays of $\tau \to \mu \gamma$ and $\mu \to e\gamma$. In particular, we consider two kinds of assumption on the structures in the Majorana mass matrix and the neutrino Yukawa matrix. In the case of the Majorana mass matrix proportional to the unit matrix, allowing nonvanishing $CP$-violating parameters in the neutrino Yukawa matrix, we find that the branching ratio of $\tau \to \mu \gamma$ can be larger than ${10}^{-9}$ within the improved experimental limit of $\mu \to e\gamma$. We also consider the neutrino Yukawa matrix that includes the mixing only in the second and third generations, and we find that a larger branching ratio of $\tau \to \mu \gamma$ than ${10}^{-9}$ is possible while satisfying the recent constraints.

We report a measurement of the $B^0$ and $B^{+}$ meson decays to the $D_s^{-}{K}_S^0{\pi }^{+}$ and $D_s^{-}{K}^{+}{K}^{+}$ final states, respectively, using $657\times 10^{6}B\overline{B}$ pairs collected at the $\mathrm{{\rm Y}}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. Using the $D_s^{-}\to \varphi {\pi }^{-}$, $K^{*}(892{)}^0{K}^{-}$ and $K_S^0{K}^{-}$ decay modes for the $D_s$ reconstruction, we measure the following branching fractions: $\mathcal{B}(B^0\to D_s^{-}{K}_S^0{\pi }^{+})=[0.47\pm 0.06(\text{stat})\pm 0.05(\text{syst})]\times 10^{-4}$ and $\mathcal{B}(B^{+}\to D_s^{-}{K}^{+}{K}^{+})=[0.93\pm 0.22(\text{stat})\pm 0.10(\text{syst})]\times 10^{-5}$. We find the ratio of the branching fraction of $B^{+}\to D_s^{-}{K}^{+}{K}^{+}$ to that of the analogous Cabibbo-favored $B^{+}\to D_s^{-}{K}^{+}{\pi }^{+}$ decay to be ${\mathcal{R}}_{\mathcal{B}}=0.054\pm 0.013(\text{stat})\pm 0.006(\text{syst})$, which is consistent with the naive factorization model. We also observe a deviation of the $D_{s}K$ invariant-mass distribution from the three-body phase-space model for both studied decays.

The physics responsible for gauge coupling unification may also induce small neutrino masses. We propose a novel gauge-mediated radiative seesaw mechanism for calculable neutrino masses. These arise from quantum corrections mediated by new $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ (3-3-1) gauge bosons and the physics driving gauge coupling unification. Gauge couplings unify for a 3-3-1 scale in the TeV range, making the model directly testable at the LHC.

In this paper, we show that there is no in-principle obstruction to obtain a Kim-Shifman-Vainshtein-Zakharov axion with a decay constant in the phenomenologically allowed range in certain $E_8\times E_8$ heterotic string models. These models have an enhanced symmetry locus in the moduli space and a nonuniversal, Kähler moduli-dependent Fayet–Iliopoulos term which vanishes at this locus. Close to this locus, the Fayet–Iliopoulos term is small and can lead to an axion decay constant significantly lower than the string scale. In this way, the no-go arguments of Svrček and Witten, which are based on a universal, dilaton-dependent Fayet–Iliopoulos term, can be avoided. The relevant axion originates from phases of bundle moduli which correspond to deformations away from the enhanced symmetry locus. We construct an explicit example, based on a heterotic line bundle standard model, with all the required ingredients.

In a recent work we have proposed a perturbative approach for the study of the phase transition of pure Yang-Mills theories at finite temperature. This is based on a simple massive extension of background field methods in the Landau-DeWitt gauge, where the gluon mass term is related to the existence of Gribov ambiguities. We have shown that a one-loop calculation of the background field effective potential describes well the phase structure of the SU(2) and SU(3) theories. Here, we present the calculation of the next-to-leading-order contribution in perturbation theory for the SU(2) case. In particular, we compute the background field effective potential at two-loop order and the corresponding Polyakov loop, a gauge invariant order parameter of the transition, at one-loop order. We show that the two-loop correction brings the critical temperature closer to its actual value as compared to the previous one-loop result. We also compute the thermodynamic pressure as a function of the temperature and show that two-loop contributions play an important role in the vicinity of the phase transition.

The present work shows that a properly chosen ordering of operators can restore unitarity in anisotropic quantum cosmological models. Bianchi V and Bianchi IX models with a perfect fluid are worked out. A transformation of coordinates takes the Hamiltonian to that of an inverse square potential which has equal deficiency indices; thus, a self-adjoint extension is possible. Although not clearly detected before, we show here that isotropic models are also apt to violate the conservation of probability for careless operator ordering.

We investigate some cosmological models arising from a nonminimal coupling of a fermionic field to gravity in the geometrical setting of Einstein-Cartan-Sciama-Kibble gravity. In the presence of torsion, we discuss the role played by the nonminimal coupling together with fermionic self-interaction potentials in facing problems such as cosmological singularity, inflation, and dark energy.

Quantum states of ultracold neutrons in a gravitational field are characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts—which we call the Stern-Gerlach shift, interference shift, and spectator-state shift—appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

For the extension of the Standard Model with light hidden photons, we present preliminary estimates of the signal rate expected at the recently proposed fixed target SHiP experiment exploiting the CERN SPS beam of 400 GeV protons.

Moduli fields with Planck-suppressed couplings to light species are common in string compactifications. Decays of these moduli can reheat the Universe at a late time and produce dark matter nonthermally. For generic moduli fields motivated by string theory with masses similar to that of the gravitino and TeV-scale superpartners in the minimal supersymmetric Standard Model (MSSM), the nonthermal production of the lightest superpartner (LSP) tends to create an unacceptably large relic density or too strong of an indirect detection signal. We call this the moduli-induced LSP problem of the MSSM. In this paper we investigate extensions of the MSSM containing new LSP candidates that can alleviate this tension. We examine the viability of this scenario in models with light Abelian and non-Abelian hidden sectors and symmetric or asymmetric dark matter. In these extensions it is possible, though somewhat challenging, to avoid a moduli-induced LSP problem. In all but the asymmetric scenario, the LSP can account for only a small fraction of the observed dark matter density.

With the goal of generating the Galactic Center gamma-ray excess, we revisit models in which the dark matter interacts with the Standard Model through the exchange of a new neutral gauge boson, $Z^{\prime }$. We find several scenarios that can account for this signal, while respecting all existing constraints from colliders and direct-detection experiments. In such models, the $Z^{\prime }$ either 1) couples axially to light quarks and is leptophobic, 2) couples dominantly to the third generation, or 3) is near resonance, $m_{Z^{\prime }}\approx 2m_{\mathrm{DM}}$. We identify an example of an anomaly-free ${\mathrm{U}(1)}^{\prime }$ that leads to an axial and leptophobic $Z^{\prime }$. Many of the models presented here are within the reach of near-future direct-detection experiments, such as LUX and XENON1T.