In the standard structure formation scenario based on the cold dark matter paradigm, galactic halos are predicted to contain a large population of dark matter subhalos. While the most massive members of the subhalo population can appear as luminous satellites and be detected in optical surveys, establishing the existence of the low mass and mostly dark subhalos has proven to be a daunting task. Galaxy-scale strong gravitational lenses have been successfully used to study mass substructures lying close to lensed images of bright background sources. However, in typical galaxy-scale lenses, the strong lensing region only covers a small projected area of the lens’s dark matter halo, implying that the vast majority of subhalos cannot be directly detected in lensing observations. In this paper, we point out that this large population of dark satellites can collectively affect gravitational lensing observables, hence possibly allowing their statistical detection. Focusing on the region of the galactic halo outside the strong lensing area, we compute from first principles the statistical properties of perturbations to the gravitational time delay and position of lensed images in the presence of a mass substructure population. We find that in the standard cosmological scenario, the statistics of these lensing observables are well approximated by Gaussian distributions. The formalism developed as part of this calculation is very general and can be applied to any halo geometry and choice of subhalo mass function. Our results significantly reduce the computational cost of including a large substructure population in lens models and enable the use of Bayesian inference techniques to detect and characterize the distributed satellite population of distant lens galaxies.

I derive formulas for the real space CMB temperature and polarization by solving the first order Boltzmann equation for the Stokes parameters $I$, $Q$ and $U$.

The integrated Sachs-Wolfe (ISW) effect is a large-angle modulation of the cosmic microwave background (CMB), generated when CMB photons traverse evolving potential wells associated with large scale structure (LSS). Recent efforts have been made to reconstruct maps of the ISW signal using information from surveys of galaxies and other LSS tracers, but investigation into how survey systematics affect their reliability has so far been limited. Using simulated ISW and LSS maps, we study the impact of galaxy survey properties and systematic errors on the accuracy of a reconstructed ISW signal. We find that systematics that affect the observed distribution of galaxies along the line of sight, such as photo-$z$ and bias-evolution related errors, have a relatively minor impact on reconstruction quality. In contrast, however, we find that direction-dependent calibration errors can be very harmful. Specifically, we find that, in order to avoid significant degradation of our reconstruction quality statistics, direction-dependent number density fluctuations due to systematics must be controlled so that their variance is smaller than ${10}^{-6}$ (which corresponds to a 0.1% calibration). Additionally, we explore the implications of our results for attempts to use reconstructed ISW maps to shed light on the origin of large-angle CMB alignments. We find that there is only a weak correlation between the true and reconstructed angular momentum dispersion, which quantifies alignment, even for reconstructed ISW maps which are fairly accurate overall.

The drift in the redshift of objects passively following the cosmological expansion has long been recognized as a key model-independent probe of cosmology. Here, we study the cosmological relevance of measurements of time or redshift derivatives of this drift, arguing that the combination of first and second redshift derivatives is a powerful test of the $\mathrm{\Lambda }\mathrm{CDM}$ cosmological model. In particular, the latter can be obtained numerically from a set of measurements of the drift at different redshifts. We show that, in the low-redshift limit, a measurement of the derivative of the drift can provide a constraint on the jerk parameter, which is $j=1$ for flat $\mathrm{\Lambda }\mathrm{CDM}$, while generically $j\ne 1$ for other models. We emphasize that such a measurement is well within the reach of the ELT-HIRES and SKA Phase 2 array surveys.

We study flavor-changing neutral current decays of the top quark in the context of general warped extra dimensions, where the five-dimensional (5D) metric is slightly modified from 5D anti–de Sitter (${\mathrm{AdS}}_5$). These models address the Planck-electroweak hierarchies of the Standard Model and can obey all the low-energy flavor bounds and electroweak precision tests, while allowing the scale of new physics to be at the TeV level, and thus within the reach of the LHC at Run II. We perform the calculation of these exotic top decay rates for the case of a bulk Higgs, and thus include in particular the effect of the additional Kaluza-Klein (KK) Higgs modes running in the loops, along with the usual KK fermions and KK gluons.

A thermally decoupled hidden sector of particles, with a mass gap, generically enters a phase of cannibalism in the early Universe. The Standard Model sector becomes exponentially colder than the hidden sector. We propose the cannibal dark matter framework, where dark matter resides in a cannibalizing sector with a relic density set by 2-to-2 annihilations. Observable signals of cannibal dark matter include a boosted rate for indirect detection, new relativistic degrees of freedom, and warm dark matter.

If the diphoton excess at 750 GeV hinted by the 2015 data at the LHC is explained in terms of a scalar resonance participating in the breaking of the electroweak symmetry, this resonance must be accompanied by other scalar states for perturbative unitarity in vector-boson scattering to be preserved. The simplest setup consistent with perturbative unitarity and with the data of the diphoton excess is the Georgi-Machacek model. The custodial singlet of the model is responsible for the diphoton excess; it is mainly produced in the diphoton fusion channel, and its loop-induced coupling to the photon pairs is enhanced by the doubly charged scalar with its large (dimensionful) coupling to the custodial singlet.

The axial couplings of the low lying baryons are evaluated using a total of five ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using the Iwasaki gauge action and two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values at two values of the coupling constant. The lattice spacings, determined using the nucleon mass, are $a=0.082\mathrm{fm}$ and $a=0.065\mathrm{fm}$, and the simulations cover a pion mass in the range of about 210 MeV to 430 MeV. We study the dependence of the axial couplings on the pion mass in the range of about 210 MeV to 430 MeV as well as the SU(3) breaking effects as we decrease the light quark mass toward its physical value.

We consider the azimuthal correlations of charged hadron pairs with large total transverse momentum and small relative momentum, produced in proton-proton collisions with one transversely polarized proton. One of these correlations directly probes the chiral-odd transversity parton distribution in connection with a chiral-odd interference fragmentation function. We present predictions for this observable based on previous extractions of transversity (from charged pion pair production in semi-inclusive deep-inelastic scattering) and of the interference fragmentation function (from the production of back-to-back charged pion pairs in electron-positron annihilations). All analyses are performed in the framework of collinear factorization. We compare our predictions to the recent data on proton-proton collisions released by the STAR Collaboration at RHIC, and we find them reasonably compatible. This comparison confirms for the first time the predicted role of transversity in proton-proton collisions, and it allows us to test its universality.

Motivated by the emerging possibilities to study threshold pion electroproduction at large momentum transfers at Jefferson Laboratory following the 12 GeV upgrade, we provide a short theory summary and an estimate of the nucleon axial form factor for large virtualities in the $Q^2=1–10{\mathrm{GeV}}^2$ range using next-to-leading-order light-cone sum rules.

We suggest a theoretical framework for the description of double photon and proton-antiproton photoproduction off the proton $\gamma +p\to 2\gamma +p$ and $\gamma +p\to \overline{p}p+p$, which takes into account the contribution of the scalar mesons $f_0(1370)$, $f_0(1500)$, and $f_0(1710)$. These scalars are considered as mixed states of a glueball, nonstrange and strange quarkonia. Our framework is based on the use of effective hadronic Lagrangians that phenomenologically take into account two-gluon exchange effects governing the $\gamma +p\to 2\gamma +p$ and $\gamma +p\to \overline{p}p+p$ processes. Present results can be used to guide the possible search for these reactions by the GlueX Collaboration at JLab.

We study the effect of a hot and dense medium on the binding energy of hadronic molecules with open-charm mesons. We focus on a recent chiral quark-model-based prediction of a molecular state in the $N\overline{D}$ system. We analyze how the two-body thresholds and the hadron-hadron interactions are modified when quark and meson masses and quark-meson couplings change in a function of the temperature and baryon density according to predictions of the Nambu–Jona-Lasinio model. We find that in some cases the molecular binding is enhanced in medium as compared to their free-space binding. We discuss the consequences of our findings for the search for exotic hadrons in high-energy heavy-ion collisions as well as in the forthcoming facilities FAIR or J-PARC.

We analyze the second-class current decays ${\tau }^{-}\to {\pi }^{-}{\eta }^{(\prime )}{\nu }_{\tau }$ in the framework of chiral perturbation theory with resonances. Taking into account ${\pi }^0\text{−}\eta \text{−}{\eta }^{\prime }$ mixing, the ${\pi }^{-}{\eta }^{(\prime )}$ vector form factor is extracted, in a model-independent way, using existing data on the ${\pi }^{-}{\pi }^0$ one. For the participant scalar form factor, we have considered different parametrizations ordered according to their increasing fulfillment of analyticity and unitarity constraints. We start with a Breit-Wigner parametrization dominated by the $a_0(980)$ scalar resonance and after we include its excited state, the $a_0(1450)$. We follow by an elastic dispersion relation representation through the Omnès integral. Then, we illustrate a method to derive a closed-form expression for the ${\pi }^{-}\eta$, ${\pi }^{-}{\eta }^{\prime }$ (and $K^{-}{K}^0$) scalar form factors in a coupled-channels treatment. Finally, predictions for the branching ratios and spectra are discussed emphasizing the error analysis. An interesting result of this study is that both ${\tau }^{-}\to {\pi }^{-}{\eta }^{(\prime )}{\nu }_{\tau }$ decay channels are promising for the soon discovery of second-class currents at Belle-II. We also predict the relevant observables for the partner ${\eta }_{\ell 3}^{(\prime )}$ decays, which are extremely suppressed in the Standard Model.

We continue to study the response of black-hole space-times on the presence of additional strong sources of gravity. Restricting ourselves to static and axially symmetric (electro)vacuum exact solutions of Einstein’s equations, we first considered the Majumdar-Papapetrou solution for a binary of extreme black holes in a previous paper, while here we deal with a Schwarzschild black hole surrounded by a concentric thin ring described by the Bach-Weyl solution. The geometry is again revealed on the simplest invariants determined by the metric (lapse function) and its gradient (gravitational acceleration), and by curvature (Kretschmann scalar). Extending the metric inside the black hole along null geodesics tangent to the horizon, we mainly focus on the black-hole interior (specifically, on its sections at constant Killing time) where the quantities behave in a way indicating a surprisingly strong influence of the external source. Being already distinct on the level of potential and acceleration, this is still more pronounced on the level of curvature: for a sufficiently massive and/or nearby (small) ring, the Kretschmann scalar even becomes negative in certain toroidal regions mostly touching the horizon from inside. Such regions have been interpreted as those where magnetic-type curvature dominates, but here we deal with space-times which do not involve rotation and the negative value is achieved due to the electric-type components of the Riemann/Weyl tensor. The Kretschmann scalar also shapes rather nontrivial landscapes outside the horizon.

Although black holes are eminent manifestations of very strong gravity, the geometry of space-time around and even inside them can be significantly affected by additional bodies present in their surroundings. We study such an influence within static and axially symmetric (electro)vacuum space-times described by exact solutions of Einstein’s equations, considering astrophysically motivated configurations (such as black holes surrounded by rings) as well as those of pure academic interest (such as specifically “tuned” systems of multiple black holes). The geometry is represented by the simplest invariants determined by the metric (the lapse function) and its gradient (gravitational acceleration), with special emphasis given to curvature (the Kretschmann and Ricci-square scalars). These quantities are analyzed and their level surfaces plotted both above and below the black-hole horizons, in particular near the central singularities. Estimating that the black hole could be most strongly affected by the other black hole, we focus, in this first paper, on the Majumdar-Papapetrou solution for a binary black hole and compare the deformation caused by “the other” hole (and the electrostatic field) with that induced by rotational dragging in the well-known Kerr and Kerr-Newman solutions.

We establish the Hamiltonian analysis and the canonical path integral for a local formulation of vacuum energy sequestering. In particular, by considering the state of the Universe as a superposition of vacuum states corresponding to different values of the cosmological and gravitational constants, the path integral is extended to include integrations over the cosmological and gravitational constants. The result is an extension of the Ng–van Dam form of the path integral of unimodular gravity. It is argued to imply a relation between the fraction of the most likely values of the gravitational and cosmological constants and the average values of the energy density and pressure of matter over spacetime. Finally, we construct and analyze a Becchi-Rouet-Stora-Tyutin-exact formulation of the theory, which can be considered as a topological field theory.

Dijet mass distributions can be used to search for spin-0 resonances that couple to two gluons. I show that there is a substantial impact on such searches from the interference between the resonant signal and the continuum QCD background amplitudes. The signal dijet mass distribution is qualitatively modified by this interference, compared to the naive expectation from considering only the pure resonant contribution, even if the total width of the resonance is minimal and very small compared to the experimental dijet mass resolution. The impact becomes more drastic as the total width of the resonance increases. These considerations are illustrated using examples relevant to the 750 GeV diphoton excess recently observed at the LHC.

In this paper we consider particle production at a future circular hadron collider with 100 TeV center-of-mass energy within the Standard Model, and in particular their QCD aspects. Accurate predictions for these processes pose severe theoretical challenges related to large hierarchies of scales and possible large multiplicities of final-state particles. We investigate scaling patterns in multijet-production rates allowing to extrapolate predictions to very high final-state multiplicities. Furthermore, we consider large-area QCD jets and study the expectation for the mean number of subjets to be reconstructed from their constituents and confront these with analytical resummed predictions and with the expectation for boosted hadronic decays of top quarks and $W$ bosons. We also discuss the validity of Higgs effective field theory in making predictions for Higgs-boson production in association with jets. Finally, we consider the case of new physics searches at such a 100 TeV hadron-collider machine and discuss the expectations for corresponding Standard-Model background processes.

In this work, we perform a dynamical study of the $B^{(*)}$ and $\overline{K}$ interaction and show that the newly reported $X(5568)$ or $X(5616)$ cannot be assigned to be an isovector $B\overline{K}$ or $B^{*}\overline{K}$ molecular state. We continue to investigate the isoscalar $B^{(*)}\overline{K}$ systems, and the $B^{(*)}\overline{K}$ systems with isospin $I=0$, 1, and predict the existence of several isoscalar $B^{(*)}{\overline{K}}^{(*)}$ molecular states. A new task of exploring open-bottom molecular states will be created for future experiments.

We study the observed $B^{-}\to X(3823)K^{-}$ decay via the rescattering mechanism and show that this branching ratio is well reproduced by this mechanism. We further extend this theoretical framework to investigate the decays of $B^{-}\to {\eta }_{c2}({{}^{1}D}_2)/{\psi }_3({{}^{3}D}_3)K^{-}$, where the ${\eta }_{c2}({{}^{1}D}_2)$ and the ${\psi }_3({{}^{3}D}_3)$ are $D$-wave charmonium partners of the $X(3823)$. Our results show that the branching ratios, $B^{-}\to {\eta }_{c2}({{}^{1}D}_2)K^{-}$ and $B^{-}\to {\psi }_3({{}^{3}D}_3)K^{-}$, are of the order of ${10}^{-5}$, which can be accessible at LHCb, Belle and forthcoming BelleII.