We present a detailed study of open heavy flavor production in high-energy $pp$ collisions at the LHC in the color dipole framework. The transverse momentum distributions of produced $b$-jets, accounting for the jet energy loss, as well as produced open charm $D$ and bottom $B$ mesons in distinct rapidity intervals relevant for LHC measurements are computed. The dipole model results for the differential $b$-jet production cross section are compared to the recent ATLAS and CMS data while the results for $D$ and $B$ mesons production cross sections—to the corresponding LHCb data. Several models for the phenomenological dipole cross section have been employed to estimate theoretical uncertainties of the dipole model predictions. We demonstrate that the primordial transverse momentum distribution of the projectile gluon significantly affects the meson spectra at low transverse momenta and contributes to the largest uncertainty of the dipole model predictions.

We study the effective potential in renormalizable quantum gravity with a single dimensionless conformal coupling without a Landau pole. In order to describe a background-free dynamics at the Planck scale and beyond, the conformal-factor field is quantized exactly in a nonperturbative manner. Since this field does not receive renormalization, the field-independent constant in the effective potential becomes itself invariant under the renormalization group flow. That is to say, it gives the physical cosmological constant. We explicitly calculate the physical cosmological constant at the one-loop level in the Landau gauge. We find that it is given by a function of renormalized quantities of the cosmological constant, the Planck mass, and the coupling constant, and it should be the observed value. It will give a new perspective on the cosmological constant problem free from an ultraviolet cutoff.

We apply the replica trick to compute the entropy of a cylinder amplitude in string theory. We focus on the contribution from nonperturbative winding modes and impose tadpole cancellation to understand the correct prescription for integrating over moduli. Choosing the entangling surface to cut longitudinally over the whole length of the cylinder, we obtain an answer that is interpreted as the entropy of a density matrix. We recast this result in target space language, in both the open and closed string picture.

We study four-dimensional $\mathcal{N}=2$ supersymmetric $U(N)$ gauge theory with $2N$ fundamental hypermultiplets in the self-dual $\mathrm{\Omega }$-background. The partition function simplifies at special points of the parameter space and is related to the partition function of two-dimensional Yang-Mills theory on $S^2$. We also consider the insertion of a Wilson loop operator in two-dimensional Yang-Mills theory and find the corresponding operator in the four-dimensional $\mathcal{N}=2$ gauge theory.

We initiate a study of the bootstrap program for field theories with Bondi-Metzner-Sachs (BMS) symmetry. Specifically, we look at two-dimensional field theories with ${\mathrm{BMS}}_3$ symmetry, and using the highest weight representations we construct the BMS bootstrap equation by formulating the notion of crossing symmetry in the four-point functions of these field theories. In the limit of large central charge, we find analytic expressions for the BMS blocks that are the basic ingredients for the solution of the bootstrap equation. This constitutes, to the best of our knowledge, the first example of the formulation and significant steps toward the solution of a bootstrap equation in a theory which is not a relativistic conformal field theory.

We obtain a family of exact solutions describing magnetized black holes in an external gravitational field. Locally the solutions can be interpreted as representing the near-horizon region of a black hole, which interacts with a surrounding matter distribution producing a strong magnetic field. Thus, the solutions reflect the influence of both a gravitational and an electromagnetic external potential in the strong field regime. The static members in the family are generalizations of the Schwarzschild solution in the described environment, while the rotating ones generalize the magnetized Reissner-Nordström solution when the influence of an external gravitational source is also taken into account. Technically, the solutions are obtained by means of a Harrison transformation, applied on the (electro-)vacuum distorted black holes constructed by Bretón et al. We examine the thermodynamical properties of the solutions, and compare them with the corresponding isolated black holes, and with the particular cases when the interaction with only one of the external potentials is taken into account. For the static black holes the influence of the external gravitational and magnetic fields is factorized in a sense, both affecting different properties, and leaving the rest intact. For the rotating solutions the external gravitational and magnetic fields are coupled through the conditions for avoiding conical singularities. The Meissner effect is observed for extremal rotating solutions only in the zero-charge limit, similar to the magnetized Reissner-Nordström black hole.

The gedanken experiment by Wald to destroy a black hole using a test particle in the equatorial plane is adapted to the case of extremal magnetized black holes. We find that the presence of external magnetic fields resulting from the “Ernst magnetization” permits a test particle to have strong enough energy to destroy the black hole. However, the corresponding effective potentials show that such particles would never reach the horizon.

There is increasing numerical evidence that scalar fields can form long-lived quasibound states around black holes. Recent perturbative and numerical relativity calculations have provided further confirmation in a variety of physical systems, including both static and accreting black holes, and collapsing fermionic stars. In this work, we investigate this issue yet again in the context of gravitationally unstable boson stars leading to black-hole formation. We build a large sample of spherically symmetric initial models, both stable and unstable, incorporating a self-interaction potential with a quartic term. The three different outcomes of unstable models, namely, migration to the stable branch, total dispersion, and collapse to a black hole, are also present for self-interacting boson stars. Our simulations show that for black hole-forming models, a scalar-field remnant is found outside the black-hole horizon, oscillating at a different frequency than that of the original boson star. This result is in good agreement with recent spherically symmetric simulations of unstable Proca stars collapsing to black holes [N. Sanchis-Gual, C. Herdeiro, E. Radu, J. C. Degollado, and J. A. Font, Phys. Rev. D 95, 104028 (2017).].

The purely thermal nature of Hawking radiation from evaporating black holes leads to the information loss paradox. A possible route to its resolution could be if (enough) correlations are shown to be present in the radiation emitted from evaporating black holes. A reanalysis of Hawking’s derivation including the effects of self-interactions in general relativity shows that the emitted radiation does deviate from pure thermality; however no correlations exist between successively emitted Hawking quanta. We extend the calculations to Einstein-Gauss-Bonnet gravity and investigate if higher curvature corrections to the action lead to some new correlations in the Hawking spectra. The effective trajectory of a massless shell is determined by solving the constraint equations and the semiclassical tunneling probability is calculated. As in the case of general relativity, the radiation is no longer thermal and there is no correlation between successive emissions. The absence of any extra correlations in the emitted radiations even in Gauss-Bonnet gravity suggests that the resolution of the paradox is beyond the scope of semiclassical gravity.

We explore the sensitivity of weak-lensing observables to the expansion history of the Universe and to the growth of cosmic structures, as well as the relative contribution of both effects to constraining cosmological parameters. We utilize ray-tracing dark-matter-only $N$-body simulations and validate our technique by comparing our results for the convergence power spectrum with analytic results from past studies. We then extend our analysis to non-Gaussian observables which cannot be easily treated analytically. We study the convergence (equilateral) bispectrum and two topological observables, lensing peaks and Minkowski functionals, focusing on their sensitivity to the matter density ${\mathrm{\Omega }}_m$ and the dark energy equation of state $w$. We find that a cancellation between the geometry and growth effects is a common feature for all observables and exists at the map level. It weakens the overall sensitivity by factors of up to 3 and 1.5 for $w$ and ${\mathrm{\Omega }}_m$, respectively, with the bispectrum worst affected. However, combining geometry and growth information alleviates the degeneracy between ${\mathrm{\Omega }}_m$ and $w$ from either effect alone. As a result, the magnitudes of marginalized errors remain similar to those obtained from growth-only effects, but with the correlation between the two parameters switching sign. These results shed light on the origin of the cosmology sensitivity of non-Gaussian statistics and should be useful in optimizing combinations of observables.

In this work, we study the imprint of an individual primordial cosmic string within a Hubble patch on the inflationary power spectrum. A straight cosmic string induces two distinct contributions to the curvature perturbations power spectrum. The first type of correction respects the translation invariance while violating isotropy. This generates quadrupolar statistical anisotropy in cosmic microwave background maps, which is constrained by the Planck data. The second contribution breaks both homogeneity and isotropy, generating a dipolar power asymmetry in the variance of temperature fluctuations with its amplitude falling on small scales. We show that the strongest constraint on the tension of primordial cosmic strings is obtained from the quadrupolar anisotropy and argue that the mass scale of the underlying theory responsible for the formation of the string cannot be much higher than the grand unified theory scale. The predictions for the diagonal and off-diagonal components of the cosmic microwave background angular power spectrum induced by the string are presented.

In this paper we provide a new expression for the variation of the inflaton field $\mathrm{\Delta }\varphi$ during the horizon crossing epoch in the context of single field slow roll inflationary models. Such an expression represents a generalization of the well-known Lyth bound. We also explore the consequences of a detection of permille order of the tensor-to-scalar ratio amplitude, $r$, as well as an improvement on the estimation of the scalar spectral index, $n_s$ and its running ${\alpha }_s$, by the upcoming cosmic microwave background (CMB) polarization experiments that will provide plausible constraints on the quantity $\mathrm{\Delta }\varphi$ during the horizon exit moment. In addition we discuss the relation between the local variation of the field and the possibilities of an eternal inflation. The results of the analysis are completely model independent.

Proposed near-future upgrades of the current advanced interferometric gravitational wave detectors include the usage of frequency dependent squeezed light to reduce the current sensitivity-limiting quantum noise. We quantify and describe the degradation effects that spatial mode-mismatches between optical resonators have on the squeezed field. These mode-mismatches can to first order be described by scattering of light into second-order Gaussian modes. As a demonstration of principle, we also show that squeezing the second-order Hermite-Gaussian modes ${\mathrm{HG}}_{02}$ and ${\mathrm{HG}}_{20}$, in addition to the fundamental mode, has the potential to increase the robustness to spatial mode-mismatches. This scheme, however, requires independently optimised squeeze angles for each squeezed spatial mode, which would be challenging to realise in practise.

We propose a new realization of strongly interacting massive particles (SIMPs) as self-interacting dark matter, where SIMPs couple to the standard model (SM) sector through an axionlike particle. Our model overcomes major obstacles accompanying the original SIMP model, such as a missing mechanism of kinetically equilibrating SIMPs with the SM plasma as well as marginal perturbativity of the chiral Lagrangian density. Remarkably, the parameter region realizing ${\sigma }_{\mathrm{self}}/m_{\mathrm{DM}}\simeq 0.1–1{\mathrm{cm}}^2/\mathrm{g}$ is within the reach of future beam dump experiments such as the Search for Hidden Particles experiment.

We study an inverse seesaw model of neutrino mass within the framework of $S_4$ flavor symmetry from the requirement of generating nonzero reactor mixing angle ${\theta }_{13}$ along with correct dark matter relic abundance. The leading order $S_4$ model gives rise to tribimaximal-type leptonic mixing, resulting in ${\theta }_{13}=0$. Nonzero ${\theta }_{13}$ is generated at one-loop level by extending the model with additional scalar and fermion fields which take part in the loop correction. The particles going inside the loop are odd under an in-built $Z_2^{\text{Dark}}$ symmetry such that the lightest $Z_2^{\text{Dark}}$ odd particle can be a dark matter candidate. Correct neutrino and dark matter phenomenology can be achieved for such one-loop corrections either to the light neutrino mass matrix or to the charged lepton mass matrix, although the latter case is found to be more predictive. The predictions for neutrinoless double beta decay are also discussed, and inverted hierarchy in the charged lepton correction case is found to be disfavored by the latest KamLAND-Zen data.

We propose a new table-top experimental configuration for the direct detection of dark matter QCD axions in the traditional open mass window ${10}^{-6}\mathrm{eV}\lesssim m_a\lesssim {10}^{-2}\mathrm{eV}$ using nonperturbative effects in a system with nontrivial spatial topology. Different from most experimental setups found in literature on direct dark matter axion detection, which relies on $\dot{\theta }$ or $\overrightarrow{\nabla }\theta$, we found that our system is in principle sensitive to a static $\theta \ge {10}^{-14}$ and can also be used to set limit on the fundamental constant ${\theta }_{\mathrm{QED}}$ which becomes the fundamental observable parameter of the Maxwell system if some conditions are met. Furthermore, the proposed experiments can probe entire open mass window ${10}^{-6}\mathrm{eV}\lesssim m_a\lesssim {10}^{-2}\mathrm{eV}$ with the same design, which should be contrasted with conventional cavity-type experiments being sensitive to a specific axion mass. Connection with Witten effect when the induced electric charge $e^{\prime }$ is proportional to $\theta$ and the magnetic monopole becomes the dyon with nonvanishing $e^{\prime }=-e\frac{\theta }{2\pi }$ is also discussed.

We revisit the effective field theory of the standard model that is extended with sterile neutrinos, $N$. We examine the basis of complete and independent effective operators involving $N$ up to mass dimension seven (dim-7). By employing equations of motion, integration by parts, and Fierz and group identities, we construct relations among operators that were considered independent in the previous literature, and we find 7 redundant operators at dim-6, as well as 16 redundant operators and two new operators at dim-7. The correct numbers of operators involving $N$ are, without counting Hermitian conjugates, $16(L\cap B)+1(\cancel{L}\cap B)+2(\cancel{L}\cap \cancel{B})$ at dim-6 and $47(\cancel{L}\cap B)+5(\cancel{L}\cap \cancel{B})$ at dim-7. Here $L/B(\cancel{L}/\cancel{B})$ stands for lepton/baryon number conservation (violation). We verify our counting by the Hilbert series approach for $n_f$ generations of the standard model fermions and sterile neutrinos. When operators involving different flavors of fermions are counted separately and their Hermitian conjugates are included, we find there are 29 (1614) and 80 (4206) operators involving sterile neutrinos at dim-6 and dim-7, respectively, for $n_f=1$ (3).

We provide an $A_4$-based flavor symmetric scenario to accommodate the inverse seesaw mechanism for explaining light neutrino masses and mixing. We find that the lepton mixing, in particular, the tribimaximal mixing pattern and its deviation through nonzero ${\theta }_{13}$, is originated solely from the flavor structure of the lepton number violating contribution of the neutral lepton mass matrix. Here we discuss in detail how a nonzero value of ${\theta }_{13}$ is correlated with the other parameters in the framework and its impact on the Dirac $CP$ phase $\delta$. We also analyze the nonunitarity effects on the lepton-mixing matrix and its implication in terms of the lepton flavor violating decays, etc.

We investigate the physical consequences of the survival of the effects of the $U(1{)}_A$ anomaly in the chiral symmetric phase of $QCD$, and show that the free energy density is a singular function of the quark mass $m$, in the chiral limit, and that the $\sigma$ and $\overline{\pi }$ susceptibilities diverge in this limit at any $T\ge T_c$. We also show that the difference between the $\overline{\pi }$ and $\overline{\delta }$ susceptibilities diverges in the chiral limit at any $T\ge T_c$, a result which seems to be excluded by recent results of Tomiya et al. from numerical simulations of two-flavor QCD. We also discuss on the generalization of these results to the $N_f\ge 3$ model.

We calculate the invariant and helicity amplitudes for the transitions ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}^{(*)}(J^P)+J/\psi$, where the ${\mathrm{\Lambda }}^{(*)}(J^P)$ are $\mathrm{\Lambda }(sud)$-type ground and excited states with $J^P$ quantum numbers $J^P={\frac{1}{2}}^{\pm }$, ${\frac{3}{2}}^{\pm }$. The calculations are performed in the framework of a covariant confined quark model previously developed by us. We find that the values of the helicity amplitudes for the ${\mathrm{\Lambda }}^{*}(1520,{\frac{3}{2}}^{-})$ and the ${\mathrm{\Lambda }}^{*}(1890,{\frac{3}{2}}^{+})$ are suppressed compared with those for the ground state $\mathrm{\Lambda }(1116,{\frac{1}{2}}^{+})$ and the excited state ${\mathrm{\Lambda }}^{*}(1405,{\frac{1}{2}}^{-})$. This analysis is important for the identification of the hidden charm pentaquark states $P_c^{+}(4380)$ and $P_c^{+}(4450)$ which were discovered in the decay chain ${\mathrm{\Lambda }}_b^0\to P_c^{+}(\to pJ/\psi )+K^{-}$ because the cascade decay chain ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}^{*}({\frac{3}{2}}^{\pm })(\to p{K}^{-})+J/\psi$ involves the same final state.