We perform a detailed study of the geodesic equations in the spacetime of the static and rotating charged black hole corresponding to the Kerr-Newman-(A)dS spacetime. We derive the equations of motion for test particles and light rays and present their solutions in terms of the Weierstrass $\wp$, $\zeta$, and $\sigma$ functions as well as the Kleinian $\sigma$ function. With the help of parametric diagrams and effective potentials, we analyze the geodesic motion and classify the possible orbit types. This spacetime is also a solution of $f(R)$ gravity with a constant curvature scalar.

Using the coherent state functional integral expression of the partition function, we show that the sine-Gordon model on an analogue curved spacetime arises as the effective quantum field theory for phase fluctuations of a weakly imperfect Bose gas on an incompressible background superfluid flow when these fluctuations are restricted to a subspace of the single-particle Hilbert space. We consider bipartitions of the single-particle Hilbert space relevant to experiments on ultracold bosonic atomic or molecular gases, including, e.g., restriction to high- or low-energy sectors of the dynamics and spatial bipartition corresponding to tunnel-coupled planar Bose gases. By assuming full unitary quantum control in the low-energy subspace of a trapped gas, we show that (1) appropriately tuning the particle number statistics of the lowest-energy mode partially decouples the low- and high-energy sectors, allowing any low-energy single-particle wave function to define a background for sine-Gordon dynamics on curved spacetime and (2) macroscopic occupation of a quantum superposition of two states of the lowest two modes produces an analogue curved spacetime depending on two background flows, with respective weights continuously dependent on the corresponding weights of the superposed quantum states.

The twisted geometries of spin network states are described by simple twistors, isomorphic to null twistors with a timelike direction singled out. The isomorphism depends on the Immirzi parameter $\gamma$ and reduces to the identity for $\gamma =\infty$. Using this twistorial representation, we study the action of the conformal group SU(2,2) on the classical phase space of loop quantum gravity, described by twisted geometry. The generators of translations and conformal boosts do not preserve the geometric structure, whereas the dilatation generator does. It corresponds to a one-parameter family of embeddings of T*SL(2,C) in twistor space, and its action preserves the intrinsic geometry while changing the extrinsic one—that is the boosts among polyhedra. We discuss the implication of this action from a dynamical point of view and compare it with a discretization of the dilatation generator of the continuum phase space, given by the Lie derivative of the group character. At leading order in the continuum limit, the latter reproduces the same transformation of the extrinsic geometry, while also rescaling the areas and volumes and preserving the angles associated with the intrinsic geometry. Away from the continuum limit, its action has an interesting nonlinear structure but is in general incompatible with the closure constraint needed for the geometric interpretation. As a side result, we compute the precise relation between the extrinsic geometry used in twisted geometries and the one defined in the gauge-invariant parametrization by Dittrich and Ryan and show that the secondary simplicity constraints they posited coincide with those dynamically derived in the toy model of [Classical Quantum Gravity 32, 195015 (2015)].

In Haro, Amorós, and Pan [Phys. Rev. D 93, 084018 (2016)] a new cosmological model is proposed with no big bang singularity in the past, though past geodesically incomplete. This model starts with an inflationary era, follows with a stiff matter dominated period and evolves to accelerated expansion in an asymptotically de Sitter regime in a realistic fashion. The big bang singularity is replaced by a directional singularity. This singularity cannot be reached by comoving observers, since it would take them an infinite proper time lapse to go back to it. On the contrary, observers with nonzero linear momentum have the singularity at finite proper time in their past, though arbitrarily large. Hence, the time lapse from the initial singularity can be as long as desired, even infinity, depending on the linear momentum of the observer. This conclusion applies to similar inflationary models. Due to the interest of these models, we address here the properties of such singularities.

We explicitly compute the plasma wave (PW) induced by a plane gravitational wave (GW) traveling through a region of strongly magnetized plasma, governed by force-free electrodynamics. The PW comoves with the GW and absorbs its energy to grow over time, creating an essentially force-free counterpart to the inverse-Gertsenshtein effect. The time-averaged Poynting flux of the induced PW is comparable to the vacuum case, but the associated current may offer a more sensitive alternative to photodetection when designing experiments for detecting/constraining high-frequency gravitational waves. Aside from the exact solutions, we also offer an analysis of the general properties of the GW to PW conversion process, which should find use when evaluating electromagnetic counterparts to astrophysical gravitational waves that are generated directly by the latter as a second-order phenomenon.

Many models—in particular, the brane-world models with two branes—predict the existence of the scalar radion, whose mass can be somewhat smaller than those of all the Kaluza-Klein modes of the graviton and Standard Model (SM) particles. Due to its origin the radion interacts with the trace of the energy-momentum tensor of the SM. The fermion part of the radion interaction Lagrangian is different from that for the SM Higgs boson due to the presence of additional terms playing a role for off-shell fermions. It was shown previously [Phys. Rev. D 90, 095026 (2014)] that for the case of the single radion and single Higgs boson production processes in association with an arbitrary number of SM gauge bosons all the contributions to the perturbative amplitudes appearing due to these additional terms were canceled out, making the processes similar up to a replacement of masses and overall coupling constants. For the case of the associated Higgs boson-radion and the Higgs boson pair-production processes involving the SM gauge bosons, the similarity property also appears. However, a detailed consideration shows that in this case it is not enough to simply replace the masses and the constants ($m_h\to m_r$ and $v\to {\mathrm{\Lambda }}_r$). One should also rescale the triple Higgs coupling by the factor $\xi \equiv 1+\frac{m_r^2-m_h^2}{3m_h^2}$.

Recently it has been claimed that the warm dark matter (WDM) model cannot at the same time reproduce the observed Lyman-$\alpha$ forests in distant quasar spectra and solve the small-scale issues in the cold dark matter (CDM) model. As an alternative candidate, it was shown that the mixed dark matter (MDM) model that consists of WDM and CDM can satisfy the constraint from Lyman-$\alpha$ forests and account for the “missing satellite problem” as well as the reported 3.5 keV anomalous x-ray line. We investigate observational constraints on the MDM model using strong gravitational lenses. We first develop a fitting formula for the nonlinear power spectra in the MDM model by performing $N$-body simulations and estimate the expected perturbations caused by line-of-sight structures in four quadruply lensed quasars that show anomaly in the flux ratios. Our analysis indicates that the MDM model is compatible with the observed anomaly if the mass fraction of the warm component is smaller than 0.47 at the 95% confidence level. The MDM explanation to the anomalous x-ray line and the small-scale issues is still viable even after this constraint is taken into account.

We show that the subset of high-energy neutrino events detected by IceCube which correlate with the Galactic center (within uncertainties of their reconstructed arrival directions) could originate in the collisions of protons accelerated by the Sagittarius ${\mathrm{A}}^{*}$ disk dynamo. Under very reasonable assumptions on source parameters, we demonstrate that the supermassive black hole at the center of the Galaxy could launch protons and nuclei with multi-PeV energies. Acceleration of these particles in a period of seconds up to Lorentz factors of $\sim 10^{7.5}$ is possible by means of the Blandford-Znajek mechanism, which wires the spinning magnetosphere of Sagittarius ${\mathrm{A}}^{*}$ as a Faraday unipolar inductor. During the acceleration process, the $\sim \mathrm{PeV}$ progenitors of $\sim 50\mathrm{TeV}$ neutrinos radiate curvature photons in the keV energy range. We show that IceCube neutrino astronomy with photon tagging on the Chandra X-Ray Observatory could provide a valuable probe for the Blandford-Znajek acceleration mechanism. We also argue that EeV neutrinos, which may be produced in a similar fashion during the merging of binary black holes, could become the smoking gun for particle acceleration in a one-shot boost.

We analyze the equation of state of $2+1$ flavor lattice QCD at zero baryon density by constructing a simple quark-hadron hybrid model that has both quark and hadron components simultaneously. We calculate the hadron and quark contributions separately and parameterize those to match with lattice QCD data. Lattice data on the equation of state are decomposed into hadron and quark components by using the model. The transition temperature is defined by the temperature at which the hadron component is equal to the quark one in the equation of state. The transition temperature thus obtained is about 215 MeV; this is somewhat higher than the chiral and the deconfinement pseudocritical temperatures defined by the temperature at which the susceptibility or the absolute value of the derivative of the order parameter with respect to temperature becomes maximum.

Higgs boson mass measurement at $\sim 125\mathrm{GeV}$ points to a high scale for supersymmetry (SUSY) specifically the scalar masses. If all the scalars are heavy, the supersymmetric contribution to the leptonic $g-2$ moments will be significantly reduced. On the other hand, the Brookhaven experiment indicates a $\sim 3\sigma$ deviation from the standard model prediction. Here we analyze the leptonic $g-2$ moments in an extended minimal supersymmetric standard model (MSSM) with inclusion of a vectorlike leptonic generation which brings in new sources of $CP$ violation. In this work we consider the contributions to the leptonic $g-2$ moments arising from the exchange of charginos and neutralinos, sleptons and mirror sleptons, and from the exchange of $W$ and $Z$ bosons and of leptons and mirror leptons. We focus specifically on the $g-2$ moments for the muon and the electron where sensitive measurements exist. Here it is shown that one can get consistency with the current data on $g-2$ under the Higgs boson mass constraint. Dependence of the moments on $CP$ phases from the extended sector are analyzed and it is shown that they are sensitively dependent on the phases from the new sector. It is shown that the corrections to the leptonic moments arising from the extended MSSM sector will be nonvanishing even if the SUSY scale extends into the PeV region.

Motivated by the recent excess in the diphoton invariant mass near 750 GeV, we explore a supersymmetric extension of the Standard Model that includes the minimal set of superpartners as well as additional Dirac partner chiral superfields in the adjoint representation for each gauge group. The bino partner pseudoscalar is identified as the 750 GeV resonance, while superpotential interactions between it and the gluino (wino) partners yield production via gluon fusion (decay to photon pairs) at one-loop. The gauginos and these additional adjoint superpartners are married by a Dirac mass and must also have Majorana masses. While a large wino partner Majorana mass is necessary to explain the excess, the gluino can be approximately Dirac-like, providing benefits consistent with being both “supersoft” (loop corrections to the scalar masses from Dirac gauginos are free of logarithmic enhancements) and “supersafe” (the experimental limits on the squark/gluino masses can be relaxed due to the reduced production rate). Consistency with the measured Standard Model–like Higgs boson mass is imposed, and a numerical exploration of the parameter space is provided. Models that can account for the diphoton excess are additionally characterized by having couplings that can remain perturbative up to very high scales, while remaining consistent with experimental constraints, the Higgs boson mass, and an electroweak scale which is not excessively fine-tuned.

We present an exploratory study of the gluonic structure of the $\varphi$ meson using lattice QCD (LQCD). This includes the first investigation of gluonic transversity via the leading moment of the twist-2 double-helicity-flip gluonic structure function $\mathrm{\Delta }(x,Q^2)$. This structure function only exists for targets of spin $J\ge 1$ and does not mix with quark distributions at leading twist, thereby providing a particularly clean probe of gluonic degrees of freedom. We also explore the gluonic analogue of the Soffer bound which relates the helicity flip and nonflip gluonic distributions, finding it to be saturated at the level of 80%. This work sets the stage for more complex LQCD studies of gluonic structure in the nucleon and in light nuclei where $\mathrm{\Delta }(x,Q^2)$ is an “exotic glue” observable probing gluons in a nucleus not associated with individual nucleons.

We use artificial neural networks to parametrize the shape functions in inclusive semileptonic $B$ decays without charm. Our approach avoids the adoption of functional form models and allows for a straightforward implementation of all experimental and theoretical constraints on the shape functions. The results are used to extract $|V_{ub}|$ in the GGOU framework and compared with the original GGOU paper and the latest HFAG results, finding good agreement in both cases. The possible impact of future Belle-II data on the $M_X$ distribution is also discussed.

In this work we analyze the validity of Lifshitz’s theory for the case of nonequilibrium scenarios from a full quantum dynamical approach. We show that Lifshitz’s framework for the study of the Casimir pressure is the result of considering the long-time regime (or steady state) of a well-defined fully quantized problem, subjected to initial conditions for the electromagnetic field interacting with real materials. For this, we implement the closed time path formalism developed in previous works to study the case of two half spaces (modeled as composite environments, consisting in quantum degrees of freedom plus thermal baths) interacting with the electromagnetic field. Starting from initial uncorrelated free subsystems, we solve the full time evolution, obtaining general expressions for the different contributions to the pressure that take part on the transient stage. Using the analytic properties of the retarded Green functions, we obtain the long-time limit of these contributions to the total Casimir pressure. We show that, in the steady state, only the baths’ contribute, in agreement with the results of previous works, where this was assumed without justification. We also study in detail the physics of the initial conditions’ contribution and the concept of modified vacuum modes, giving insights about in which situations one would expect a nonvanishing contribution at the steady state of a nonequilibrium scenario. This would be the case when considering finite width slabs instead of half-spaces.

In this paper we perform a systematic study of vacuum spatially flat anisotropic $[(3+D)+1]$-dimensional Einstein-Gauss-Bonnet cosmological models. We consider models that topologically are the product of two flat isotropic submanifolds with different scale factors. One of these submanifolds is three dimensional and represents our 3D space and the other is $D$ dimensional and represents extra dimensions. We consider no Ansatz on the scale factors, which makes our results quite general. With both Einstein-Hilbert and Gauss-Bonnet contributions in play and with the symmetry involved, the cases with $D=1$, $D=2$, $D=3$, and $D\ge 4$ have different dynamics due to the different structures of the equations of motion. We analytically analyze equations of motion in all cases and describe all possible regimes. It appears that the only regimes with nonsingular future asymptotes are the Kasner regime in general relativity and exponential regimes. As of the past asymptotes, for a smooth transition only the Kasner regime in Gauss-Bonnet is an option. With this at hand, we are down to only two viable regimes: the “pure” Kasner regime [transition from a high-energy (Gauss-Bonnet) to a low-energy (general relativity) Kasner regime] and a transition from a high-energy Kasner regime to an anisotropic exponential solution. It appears that these regimes take place for different signs of the Gauss-Bonnet coupling $\alpha$: the “pure” Kasner regime occurs for $\alpha >0$ at low $D$ and $\alpha <0$ for high $D$; the anisotropic exponential regime is reached only for $\alpha >0$. So if we restrain ourselves with $\alpha >0$ solutions (which would be the case, say, if we identify $\alpha$ with inverse string tension in heterotic string theory), the only late-time regimes are Kasner for $D=1$, 2 and anisotropic exponential for $D\ge 2$. Also, low-energy Kasner regimes [$a(t)\propto t^p$] have expansion rates for ($3+1$)-dimensional subspace (“our Universe”) ranging from $p=0.5$ ($D=1$) to $p=1/\sqrt{3}\approx 0.577$ ($D\to \infty$), which contradicts the dust-dominated Friedmann prediction ($p=2/3$).

We present a two-field inflation model where the inflaton field has a noncanonical kinetic term due to the presence of a dilaton field. It is a two-parameter generalization of one-parameter Brans-Dicke gravity in the Einstein frame. We show that in such an inflation model the quartic and quadratic inflaton potentials, which are otherwise ruled out by the present Planck-Keck/BICEP2 data, yield the scalar spectral index and tensor-to-scalar ratio in accordance with the present data. Such a model yields a tensor-to-scalar ratio of the order of ${10}^{-2}$ which is within the reach of $B$-mode experiments like Keck/BICEP3, CMBPol and thus can be put to the test in the near future. This model yields negligible non-Gaussianity and no isocurvature perturbations up to slow-roll approximation. Finally, we show that such a model can be realized in the realm of no-scale supergravity.

After four years of data taking, the IceCube neutrino telescope has detected 54 high-energy starting events (HESE, or contained-vertex events) with deposited energies above 20 TeV. They represent the first detection of high-energy extraterrestrial neutrinos and, therefore, the first step in neutrino astronomy. To study the energy, flavor, and isotropy of the astrophysical neutrino flux arriving at Earth, we perform different analyses of two different deposited energy intervals, [10 TeV–10 PeV] and [60 TeV–10 PeV]. We first consider an isotropic unbroken power-law spectrum and constrain its shape, normalization, and flavor composition. Our results are in agreement with the preliminary IceCube results, although we obtain a slightly softer spectrum. We also find that current data are not sensitive to a possible neutrino-antineutrino asymmetry in the astrophysical flux. Then, we show that although a two-component power-law model leads to a slightly better fit, it does not represent a significant improvement with respect to a single power-law flux. Finally, we analyze the possible existence of a north-south asymmetry, hinted at by the combination of the HESE sample with the throughgoing muon data. If we use only HESE data, the scarce statistics from the Northern Hemisphere does not allow us to reach any conclusive answer, which indicates that the HESE sample alone is not driving the potential north-south asymmetry.

In single field slow-roll inflation, one expects that the spectral index $n_s-1$ is first order in slow-roll parameters. Similarly, its running ${\alpha }_s=\mathrm{d}{n}_s/\mathrm{d}\log k$ and the running of the running ${\beta }_s=\mathrm{d}{\alpha }_s/\mathrm{d}\log k$ are second and third order and therefore expected to be progressively smaller, and usually negative. Hence, such models of inflation are in considerable tension with a recent analysis hinting that ${\beta }_s$ may actually be positive, and larger than ${\alpha }_s$. Motivated by this, in this work we ask the question of what kinds of inflationary models may be useful in achieving such a hierarchy of runnings, particularly focusing on two–field models of inflation in which the late-time transfer of power from isocurvature to curvature modes allows for a much more diverse range of phenomenology. We calculate the runnings due to this effect and briefly apply our results to assess the feasibility of finding $|{\beta }_s|\gtrsim |{\alpha }_s|$ in some specific models.

We present a new class of unified models based on $SO(10)$ symmetry which provides insights into the masses and mixings of quarks and leptons, including the neutrinos. The key feature of our proposal is the absence of the Higgs boson $10_H$ belonging to the fundamental representation that is normally employed. Flavor mixing is induced via vectorlike fermions in the $16+\overline{16}$ representation. A variety of scenarios, both supersymmetric and otherwise, are analyzed involving a ${\overline{126}}_H$ along with either a $45_H$ or a $210_H$ of the Higgs boson employed for symmetry breaking. It is shown that this framework, with only a limited number of parameters, provides an excellent fit to the full fermion spectrum, utilizing either the type-I or type-II seesaw mechanism. These flavor models can be potentially tested and distinguished in their predictions for proton decay branching ratios, which are analyzed.

A model-independent search for the Abelian $Z^{\prime }$ gauge boson in the Drell-Yan process at the LHC at $\sqrt{s}=7$ and 8 TeV is fulfilled. Estimations of the $Z^{\prime }$ axial-vector coupling $a_f^2$ to the standard model fermions, the couplings of the axial vector to lepton vector currents $a_f{v}_l$, and the couplings of the axial vector to quark vector currents $a_f{v}_q$ are derived within data on the forward-backward asymmetry presented by the CMS Collaboration. The analysis takes into consideration the behavior of the differential cross section, which exhibits itself if the derived already special relations between the couplings proper to the renormalizable theories are accounted for. In particular, they hold in all the models of Abelian $Z^{\prime }$ usually considered in the model-dependent analysis of the LHC data. The coupling values are estimated at $\sim 92\%$ confidence level by means of the maximum likelihood function. They weakly depend on the $Z^{\prime }$ mass in the investigated interval $1.2\mathrm{TeV}<m_{Z^{\prime }}<5\mathrm{TeV}$. Taking into account the dependence of $Z-Z^{\prime }$ mixing angle ${\theta }_0$ on $m_{Z^{\prime }}$ and the LEP constraints $|{\theta }_0|\sim {10}^{-3}–{10}^{-4}$, the optimistic limits on $m_{Z^{\prime }}$ are established as $3<m_{Z^{\prime }}<7–8\mathrm{TeV}$. Comparison with the results of other authors is given.