We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

The Stenzel space fourfold is a noncompact Calabi-Yau (CY) which is a higher-dimensional analogue of the deformed conifold. We consider $\mathcal{N}=(1,1)$, type-IIA, $\mathcal{N}=1$ M-theory and $\mathcal{N}=(2,0)$, type-IIB compactifications on this Stenzel space, thus examining the gravity side of potentially higher-dimensional analogues of Klebanov-Strassler-like compactifications. We construct families of $SU(4)$-structures and solve associated moduli spaces, of complex and symplectic structures amongst others. By making use of these, we can construct IIA compactifications on manifolds homeomorphic to the Stenzel space fourfold, but with complex non-CY $SU(4)$-structures. Such compactifications are sourced by a distribution of NS5-branes. The external metric is asymptotically conformal ${\mathrm{AdS}}_3$ and should thus be suitable for holography applications.

A model is discussed where all operators are constructed from a quantum scalar field whose energy spectrum takes on all real values. The Schrödinger picture wave function depends upon space and time coordinates for each particle, as well as an inexorably increasing evolution parameter $s$ which labels a foliation of spacelike hypersurfaces. The model is constructed to be manifestly Lorentz invariant in the interaction picture. Free particle states and interactions are discussed in this framework. Then, the formalism of the continuous spontaneous localization (CSL) theory of dynamical collapse is applied. The collapse-generating operator is chosen to be the particle number space-time density. Unlike previous relativistically invariant models, the vacuum state is not excited. The collapse dynamics depends upon two parameters, a parameter $\mathrm{\Lambda }$ which represents the collapse rate/volume and a scale factor $\ell$. A common example of collapse dynamics, involving a clump of matter in a superposition of two locations, is analyzed. The collapse rate is shown to be identical to that of nonrelativistic CSL when the GRW-CSL choice of $\ell =a=10^{-5}\mathrm{cm}$, is made, along with $\mathrm{\Lambda }=\lambda /a^3$ (GRW-CSL choice $\lambda =10^{-16}{s}^{-1}$). The collapse rate is also satisfactory with the choice $\ell$ as the size of the Universe, with $\mathrm{\Lambda }=\lambda /\ell a^2$. Because the collapse narrows wave functions in space and time, it increases a particle’s momentum and energy, altering its mass. It is shown that, with $\ell =a$, the change of mass of a nucleon is unacceptably large but, when $\ell$ is the size of the Universe, the change of mass over the age of the Universe is acceptably small.

The first- and second-order dissipative self-force and the first-order conservative self-force are applied together with spin-orbit coupling to the quasicircular motion of a test mass in the spacetime of a Schwarzschild black hole, for extreme or intermediate mass ratios. The partial dephasing of the gravitational waveform (at the order that is independent of the system’s mass ratio) due to the self-force is compared with that of spin-orbit coupling. We find that accurate waveforms for parameter estimation need to include both effects. Specifically, we find a particular value for the spin parameter such that the spin-orbit effect cancels out the self-force effect on the waveform. Exclusion of dephasing effects that are independent of the mass ratio therefore might lead to a nonperturbative error in the estimation of the system’s parameters.

We study the role of the Barbero-Immirzi parameter $\gamma$ and the choice of connection in the construction of (a symmetry-reduced version of) loop quantum gravity. We start with the four-dimensional Lorentzian Holst action that we reduce to three dimensions in a way that preserves the presence of $\gamma$. In the time gauge, the phase space of the resulting three-dimensional theory mimics exactly that of the four-dimensional one. Its quantization can be performed, and on the kinematical Hilbert space spanned by SU(2) spin network states the spectra of geometric operators are discrete and $\gamma$ dependent. However, because of the three-dimensional nature of the theory, its SU(2) Ashtekar-Barbero Hamiltonian constraint can be traded for the flatness constraint of an $\mathfrak{s}\mathfrak{l}(2,\mathbb{C})$ connection, and we show that this latter has to satisfy a linear simplicitylike condition analogous to the one used in the construction of spin foam models. The physically relevant solution to this constraint singles out the noncompact subgroup SU(1, 1), which in turn leads to the disappearance of the Barbero-Immirzi parameter and to a continuous length spectrum, in agreement with what is expected from Lorentzian three-dimensional gravity.

We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other items, a general relativistic dark matter metric, a dirty black hole, and a worm hole metric, the last two inspired by noncommutative geometry. The lensing in a holographic screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behavior in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases, we improve the accuracy of the lensing results for the weak and strong regimes.

The evolution of a closed Friedmann universe filled by a tachyon scalar field with a trigonometric potential and cold dark matter (CDM) is investigated. A subset of the evolutions consistent to $1\sigma$ confidence level with the Union 2.1 supernova data set is identified. The evolutions of the tachyon field are classified. Some of them evolve into a de Sitter attractor, while others proceed through a pseudotachyonic regime into a sudden future singularity. Critical evolutions leading to big brake singularities in the presence of CDM are found and a new type of cosmological evolution characterized by singularity avoidance in the pseudotachyon regime is presented.

Ultralight axions (ULAs) with masses in the range $10^{-33}\mathrm{eV}\le m_a\le 10^{-20}\mathrm{eV}$ are motivated by string theory and might contribute to either the dark-matter or dark-energy densities of the Universe. ULAs could suppress the growth of structure on small scales, lead to an altered integrated Sachs-Wolfe effect on cosmic microwave-background (CMB) anisotropies, and change the angular scale of the CMB acoustic peaks. In this work, cosmological observables over the full ULA mass range are computed and then used to search for evidence of ULAs using CMB data from the Wilkinson Microwave Anisotropy Probe (WMAP), Planck satellite, Atacama Cosmology Telescope, and South Pole Telescope, as well as galaxy clustering data from the WiggleZ galaxy-redshift survey. In the mass range $10^{-32}\mathrm{eV}\le m_a\le 10^{-25.5}\mathrm{eV}$, the axion relic-density ${\mathrm{\Omega }}_a$ (relative to the total dark-matter relic density ${\mathrm{\Omega }}_d$) must obey the constraints ${\mathrm{\Omega }}_a/{\mathrm{\Omega }}_d\le 0.05$ and ${\mathrm{\Omega }}_a{h}^2\le 0.006$ at 95% confidence. For $m_a\gtrsim 10^{-24}\mathrm{eV}$, ULAs are indistinguishable from standard cold dark matter on the length scales probed, and are thus allowed by these data. For $m_a\lesssim 10^{-32}\mathrm{eV}$, ULAs are allowed to compose a significant fraction of the dark energy.

Weak gravitational lensing is a powerful cosmological probe, with non-Gaussian features potentially containing the majority of the information. We examine constraints on the parameter triplet $({\mathrm{\Omega }}_m,w,{\sigma }_8)$ from non-Gaussian features of the weak lensing convergence field, including a set of moments (up to fourth order) and Minkowski functionals, using publicly available data from the $154{\mathrm{deg}}^2$ CFHTLenS survey. We utilize a suite of ray-tracing N-body simulations spanning 91 points in $({\mathrm{\Omega }}_m,w,{\sigma }_8)$ parameter space, replicating the galaxy sky positions, redshifts and shape noise in the CFHTLenS catalogs. We then build an emulator that interpolates the simulated descriptors as a function of $({\mathrm{\Omega }}_m,w,{\sigma }_8)$, and use it to compute the likelihood function and parameter constraints. We employ a principal component analysis to reduce dimensionality and to help stabilize the constraints with respect to the number of bins used to construct each statistic. Using the full set of statistics, we find ${\mathrm{\Sigma }}_8\equiv {\sigma }_8({\mathrm{\Omega }}_m/0.27{)}^{0.55}=0.75\pm 0.04$ (68% C.L.), in agreement with previous values. We find that constraints on the $({\mathrm{\Omega }}_m,{\sigma }_8)$ doublet from the Minkowski functionals suffer a strong bias. However, high-order moments break the $({\mathrm{\Omega }}_m,{\sigma }_8)$ degeneracy and provide a tight constraint on these parameters with no apparent bias. The main contribution comes from quartic moments of derivatives.

Discrete Abelian symmetries (${\mathbb{Z}}_N$) are a common “artifact” of beyond the standard model physics models. They provide different avenues for constructing consistent scenarios for lepton and quark mixing patterns, radiative neutrino mass generation as well as dark matter stabilization. We argue that these symmetries can arise from the spontaneous breaking of the Abelian $U(1)$ factors contained in the global flavor symmetry transformations of the gauge-invariant kinetic Lagrangian. This will be the case provided the ultraviolet completion responsible for the Yukawa structure involves scalar fields carrying nontrivial $U(1)$ charges. Guided by minimality criteria, we demonstrate the viability of this approach with two examples: first, we derive the “scotogenic” model Lagrangian, and second, we construct a setup where the spontaneous symmetry-breaking pattern leads to a ${\mathbb{Z}}_3$ symmetry which enables dark matter stability as well as neutrino mass generation at the two-loop order. This generic approach can be used to derive many other models, with residual ${\mathbb{Z}}_N$ or ${\mathbb{Z}}_{N_1}\times \cdots \times {\mathbb{Z}}_{N_k}$ symmetries, establishing an intriguing link between flavor symmetries, neutrino masses and dark matter.

We combine the twin Higgs mechanism with the paradigm of composite Higgs models. In this class of models the Higgs is a pseudo-Nambu-Goldstone boson from a strongly coupled sector near the TeV scale, and it is additionally protected by a discrete symmetry due to the twin mechanism. We discuss the model-building issues associated with this setup and quantify the tuning needed to achieve the correct electroweak vacuum and the Higgs mass. In contrast to standard composite Higgs models, the lightest resonance associated with the top sector is the uncolored mirror top, while the colored top partners can be made parameterically heavier without extra tuning. In some cases, the vector resonances are predicted to lie in the multi-TeV range. We present models where the resonances—both fermions and vectors—being heavier alleviates the pressure on naturalness coming from direct searches demonstrating that theories with low tuning may survive constraints from the Large Hadron Collider.

We show that a new strongly interacting sector can produce large enhancements of the $t\overline{t}$ asymmetries at the Tevatron. The Standard Model is extended by a new vectorlike flavor triplet of fermions and one heavy scalar, all charged under a hypercolor gauge group $\mathrm{SU}(3{)}_{\mathrm{HC}}$. This simple extension results in a number of new resonances. The predictions of our model are rather rigid once a small number of UV parameters is fixed, since all the strong dynamics can be directly taken over from our understanding of QCD dynamics. Despite the rather low hypercolor confinement scale of $\sim 100\mathrm{GeV}$, the new strongly interacting sector is stealth. It is shielded from present direct and indirect New Physics searches since the light resonances are QCD singlets, whereas the production of the heavier QCD colored resonances leads predominantly to high-multiplicity final states. Improved searches can potentially be devised using top tagged final states or decays into a small number of hypercolor pions.

The LHCb Collaboration has recently reported the observation for the first time of a spin-3 resonance in the heavy quark sector. They have shown that the ${\overline{D}}^0{K}^{-}$ structure seen in the $B_s^0\to {\overline{D}}^0{K}^{-}{\pi }^{+}$ reaction and with invariant mass 2.86 GeV is an admixture of a spin-1 and a spin-3 resonance. Motivated by the good agreement between our theoretical predictions some time ago and the properties extracted from the experiment of the $D_{s1}^{*}(2860)$ and $D_{s3}^{*}(2860)$ states, we perform an extension of the study of the strong decay properties of the $D_{sJ}^{*}(2860)$ and present the same analysis for the $D_{s1}^{*}(2700)$ and $D_{sJ}(3040)$ mesons. This provides a unified and simultaneous description of the three higher excited charmed-strange resonances observed until now. For completeness, we present theoretical results for masses and strong decays of the low-lying charmed-strange mesons and those experimental missing states which belong to the spin multiplets of the discovered $D_{s1}^{*}(2700)$, $D_{sJ}^{*}(2860)$ and $D_{sJ}(3040)$ resonances. The theoretical framework used is a constituent quark model which successfully describes hadron phenomenology from light to heavy quark sectors.

We study some rare decays of $B$ mesons involving the quark-level transition $b\to q{l}^{+}{l}^{-}(q=d,s)$ in the scalar leptoquark model. We constrain the leptoquark parameter space using the recently measured branching ratios of $B_{s,d}\to {\mu }^{+}{\mu }^{-}$ processes. Using such parameters, we obtain the branching ratios, direct $CP$-violation parameters, and isospin asymmetries in the $B\to K{\mu }^{+}{\mu }^{-}$ and $B\to \pi {\mu }^{+}{\mu }^{-}$ processes. We also obtain the branching ratios for some lepton-flavor-violating decays $B\to l_i^{+}{l}_j^{-}$. We find that the various anomalies associated with the isospin asymmetries of the $B\to K{\mu }^{+}{\mu }^{-}$ process can be explained in the scalar leptoquark model.

We present a global fit for ${\alpha }_s(m_Z)$, analyzing the available $C$-parameter data measured at center-of-mass energies between $Q=35$ and 207 GeV. The experimental data is compared to a ${\mathrm{N}}^3{\mathrm{LL}}^{\prime }+\mathcal{O}({\alpha }_s^3)+{\mathrm{\Omega }}_1$ theoretical prediction (up to the missing four-loop cusp anomalous dimension), which includes power corrections coming from a field-theoretical nonperturbative soft function. The dominant hadronic parameter is its first moment ${\mathrm{\Omega }}_1$, which is defined in a scheme which eliminates the $\mathcal{O}({\mathrm{\Lambda }}_{\mathrm{QCD}})$ renormalon ambiguity. The resummation region plays a dominant role in the $C$-parameter spectrum, and in this region a fit for ${\alpha }_s(m_Z)$ and ${\mathrm{\Omega }}_1$ is sufficient. We find ${\alpha }_s(m_Z)=0.1123\pm 0.0015$ and ${\mathrm{\Omega }}_1=0.421\pm 0.063\mathrm{GeV}$ with ${\chi }^2/\mathrm{d}.\mathrm{o}.\mathrm{f}.=0.988$ for 404 bins of data. These results agree with the prediction of universality for ${\mathrm{\Omega }}_1$ between thrust and $C$-parameter within 1-$\sigma$.

We reconsider the perturbative next-to-leading calculation of the single inclusive hadron production in the framework of the hybrid formalism, applied to hadron production in proton-nucleus collisions. Our analysis, performed in the wave function approach, differs from the previous works in three points. First, we are careful to specify unambiguously the rapidity interval that has to be included in the evolution of the leading-order eikonal scattering amplitude. This is important, since varying this interval by a number of order unity changes the next-to-leading order correction that the calculation is meant to determine. Second, we introduce the explicit requirement that fast fluctuations in the projectile wave function which only exist for a short time are not resolved by the target. This Ioffe time cutoff also strongly affects the next-to-leading order terms. Third, our result does not employ the approximation of a large number of colors. Our final expressions are unambiguous and do not coincide at next-to-leading order with the results available in the literature.

The two long-baseline experiments ICARUS and OPERA have recently provided bounds on light ($\sim \mathrm{eV}$) sterile neutrinos exploiting the results of the ${\nu }_{\mu }\to {\nu }_e$ appearance searches. Both collaborations have performed the data analysis using an effective 2-flavor description. We show that such a simplified treatment neglects sizable genuine 4-flavor effects, which are induced by the interference of the new large squared-mass splitting $\mathrm{\Delta }{m}_{14}^2$ with the atmospheric one. The inclusion in the data analysis of such effects weakens the upper bounds on the effective appearance amplitude ${\sin }^{2}2{\theta }_{\mu e}$ approximately by a factor of 2. In addition, we point out that, in a 4-flavor scheme, the flavor oscillations involve also the ${\nu }_e$ component of the CNGS beam and can suppress the theoretical expectation of the background in a substantial way. The inclusion in the data analysis of the ${\nu }_e$ disappearance effects leads to a further weakening of the upper bounds on ${\sin }^{2}2{\theta }_{\mu e}$, which overall are relaxed by a factor of 3 with respect to those obtained in the effective 2-flavor description.