An extension of Penrose’s singularity theorem is proved for spacetimes where black holes are allowed to form from nonsingular initial data. With standard assumptions about the spacetime, and assuming the existence of a trapped surface which lies outside of black hole horizons and is not completely surrounded by horizons, we show that the spacetime region outside (or on) the horizons must contain singularities. If the trapped surface is surrounded by horizons, we show that the horizons divide spacetime into causally disconnected pieces. Unlike the original Penrose theorem, our theorems provide some information about the location of singularities. We illustrate how they can be used to rule out some cosmological scenarios.

The bulk (Einstein-Hilbert) and boundary (Gibbons-Hawking) terms in the gravitational action are generally renormalized differently when integrating out quantum fluctuations. The former is affected by nonminimal couplings, while the latter is affected by boundary conditions. We use the heat kernel method to analyze this behavior for a nonminimally coupled scalar field, the Maxwell field, and the graviton field. Allowing for Robin boundary conditions, we examine in which cases the renormalization preserves the ratio of boundary and bulk terms required for the effective action to possess a stationary point. The implications for field theory and black hole entropy computations are discussed.

Recently, some Lemaı̂tre-Tolman-Bondi metrics have been considered as models alternative to the dark energy within the Friedmann-Lemaı̂tre-Robertson-Walker universes. The vanishing of the intrinsic energy of these metrics is examined since such a vanishing, in the present case and in general, could be interpreted as a necessary condition to consider the possibility of the quantum creation of a metric. More specifically, this vanishing is examined in the particular case where the Lemaı̂tre-Tolman-Bondi metrics behave asymptotically like a Friedmann-Lemaı̂tre-Robertson-Walker universe. Finally, we deal with a particular model ruled out after being confronted with cosmic observations. In a minimal agreement with this negative result, leaving aside an unstable case, the value of the intrinsic energy of this particular model does not vanish and becomes in fact minus infinite.

We derive a general formulation of the laws of irreversible thermodynamics in the presence of electromagnetism and gravity. For the handling of macroscopic material media, we use as a guide the field equations and the Noether identities of fundamental matter as deduced in the framework of gauge theories of the Poincaré $\otimes$ $U(1)$ group.

Unlike general relativity, scalar gravitational waves can be excited due to the radial oscillations in scalar-tensor gravity. To examine scalar gravitational waves in scalar-tensor gravity, we derive the evolution equations of the radial oscillations of neutron stars and determine the specific oscillation frequencies of the matter oscillations and scalar gravitational waves, where we adopt two different numerical approaches, i.e., the mode analysis and direct time evolution. As a result, we observe the spontaneous scalarization even in the radial oscillations. Depending on the background scalar field and coupling constant, the total energy radiated by the scalar gravitational waves dramatically changes, where the specific oscillation frequencies are completely the same as the matter oscillations. That is, via the direct observations of scalar gravitational waves, one cannot only reveal the gravitational theory but also extract the radial oscillations of neutron stars.

Understanding transitions between different vacua of a multiverse allowing eternal inflation is an open problem whose resolution is important to gain insights on the global structure of the spacetime as well as the problem of measure. In the classical theory, transitions from the anti–de Sitter to de Sitter vacua are forbidden due to the big-crunch singularity. In this paper, we consider toy landscape potentials: a double well and a triple well potential allowing anti–de Sitter and de Sitter vacua, in the effective dynamics of loop quantum cosmology for the $k=-1$ FRW model. We show that due to the nonperturbative quantum gravity effects as understood in loop quantum cosmology, nonsingular anti–de Sitter to de Sitter transitions are possible. In the future evolution, an anti–de Sitter bubble universe does not encounter a big-crunch singularity but undergoes a big bounce occurring at a scale determined by the underlying quantum geometry. These nonsingular transitions provide a mechanism through which a probe or a “watcher,” used to define a local measure, can safely evolve through the bounce and geodesics can be smoothly extended from anti–de Sitter to de Sitter vacua.

For the original hybrid inflation as well as the supersymmetric $F$-term and $D$-term hybrid models, we calculate the level of non-Gaussianities and the power spectrum of curvature perturbations generated during the waterfall, taking into account the contribution of entropic modes. We focus on the regime of mild waterfall, in which inflation continues for more than about 60 $e$-folds $N$ during the waterfall. We find that the associated $f_{\mathrm{NL}}$ parameter goes typically from $f_{\mathrm{NL}}\simeq -1/N_{\text{exit}}$ in the regime with $N\gg 60$, where $N_{\text{exit}}$ is the number of $e$-folds between the time of Hubble exit of a pivot scale and the end of inflation, down to $f_{\mathrm{NL}}\sim -0.3$ when $N\gtrsim 60$, i.e., much smaller in magnitude than the current bound from Planck. Considering only the adiabatic perturbations, the power spectrum is red, with a spectral index $n_s=1-4/N_{\text{exit}}$ in the case $N\gg 60$, whereas in the case $N\gtrsim 60$, it increases up to unity. Including the contribution of entropic modes does not change observable predictions in the first case, and the spectral index is too low for this regime to be viable. In the second case, entropic modes are a relevant source for the power spectrum of curvature perturbations, of which the amplitude increases by several orders of magnitude. When spectral index values are consistent with observational constraints, the primordial spectrum amplitude is much larger than the observed value and can even lead to black hole formation. We conclude that, due to the important contribution of entropic modes, the parameter space leading to a mild waterfall phase is excluded by cosmic microwave background observations for all the considered models.

There have been recent reports of unexpectedly large velocity dipole in the NRAO VLA Sky Survey (NVSS) data. We investigate whether the excess in the NVSS dipole reported can be of cosmological origin. We assume a long wavelength inhomogeneous scalar perturbation of the form $\alpha \sin (\kappa z)$ and study its effects on the matter density contrasts. Assuming an ideal fluid model, we calculate, in the linear regime, the contribution of the inhomogeneous mode to the density contrast. We calculate the expected dipole in the large scale structure (LSS) for two cases, first assuming that the mode is still superhorizon everywhere, and second assuming the mode is subhorizon but has crossed the horizon deep in matter domination and is subhorizon everywhere in the region of the survey (NVSS). In both cases, we find that such an inhomogeneous scalar perturbation is sufficient to generate the reported values of dipole anisotropy in LSS. For the superhorizon modes, we find values which are consistent with both cosmic microwave background and NVSS results. We also predict signatures for the model which can be tested by future observations.

If all or a fraction of the dark matter (DM) were coupled to a bath of dark radiation (DR) in the early Universe, we expect the combined DM-DR system to give rise to acoustic oscillations of the dark matter until it decouples from the DR. Much like the standard baryon acoustic oscillations, these dark acoustic oscillations (DAO) imprint a characteristic scale, the sound horizon of dark matter, on the matter power spectrum. We compute in detail how the microphysics of the DM-DR interaction affects the clustering of matter in the Universe and show that the DAO physics also gives rise to unique signatures in the temperature and polarization spectra of the cosmic microwave background (CMB). We use cosmological data from the CMB, baryon acoustic oscillations, and large-scale structure to constrain the possible fraction of interacting DM as well as the strength of its interaction with DR. Like nearly all knowledge we have gleaned about DM since inferring its existence this constraint rests on the betrayal by gravity of the location of otherwise invisible DM. Although our results can be straightforwardly applied to a broad class of models that couple dark matter particles to various light relativistic species, in order to make quantitative predictions, we model the interacting component as dark atoms coupled to a bath of dark photons. We find that linear cosmological data and CMB lensing put strong constraints on the existence of DAO features in the CMB and the large-scale structure of the Universe. Interestingly, we find that at most $\sim 5\%$ of all DM can be very strongly interacting with DR. We show that our results are surprisingly constraining for the recently proposed double-disk DM model, a novel example of how large-scale precision cosmological data can be used to constrain galactic physics and subgalactic structure.

We examine the processes of quantum squeezing and decoherence of density perturbations produced during a slowly contracting ekpyrotic phase in which entropic perturbations are converted to curvature perturbations before the bounce to an expanding phase. During the generation phase, the entropic fluctuations evolve into a highly squeezed quantum state, analogous to the evolution of inflationary perturbations. Subsequently, during the conversion phase, quantum coherence is lost very efficiently due to the interactions of entropy and adiabatic modes. Moreover, while decoherence occurs, the adiabatic curvature perturbations inherit their semiclassicality from the entropic perturbations. Our results confirm that, just as for inflation, an ekpyrotic phase can generate nearly scale-invariant curvature perturbations which may be treated as a statistical ensemble of classical density perturbations, in agreement with observations of the cosmic background radiation.

Detecting supernova ${\nu }_e$ is essential for testing supernova and neutrino physics, but the yields are small and the backgrounds from other channels large, e.g., $\sim {10}^2$ and $\sim {10}^4$ events, respectively, in Super-Kamiokande. We develop a new way to isolate supernova ${\nu }_e$, using gadolinium-loaded water Cherenkov detectors. The forward-peaked nature of ${\nu }_e+e^{-}\to {\nu }_e+e^{-}$ allows an angular cut that contains the majority of events. Even in a narrow cone, near-isotropic inverse beta events, ${\overline{\nu }}_e+p\to e^{+}+n$, are a large background. With neutron detection by radiative capture on gadolinium, these background events can be individually identified with high efficiency. The remaining backgrounds are smaller and can be measured separately, so they can be statistically subtracted. Super-Kamiokande with gadolinium could measure the total and average energy of supernova ${\nu }_e$ with $\sim 20\%$ precision or better each (90% C.L.). Hyper-Kamiokande with gadolinium could improve this by a factor of $\sim 5$. This precision will allow powerful tests of supernova neutrino emission, neutrino mixing, and exotic physics. Unless very large liquid argon or liquid scintillator detectors are built, this is the only way to guarantee precise measurements of supernova ${\nu }_e$.

We study high-energy emission from the mergers of neutron star binaries as electromagnetic counterparts to gravitational waves aside from short gamma-ray bursts. The mergers entail significant mass ejection, which interacts with the surrounding medium to produce similar but brighter remnants than supernova remnants in a few years. We show that electrons accelerated in the remnants can produce synchrotron radiation in x rays detectable at $\sim 100\mathrm{Mpc}$ by current generation telescopes and inverse Compton emission in gamma rays detectable by the Fermi Large Area Telescopes and the Cherenkov Telescope Array under favorable conditions. Optical synchrotron radiation is also detectable by telescopes with good angular resolution. The remnants may have already appeared in high-energy surveys such as the Monitor of All-sky X-ray Image and the Fermi Large Area Telescope as unidentified sources. We also suggest that the merger remnants could be the origin of ultrahigh-energy cosmic rays beyond the knee energy, $\sim 10^{15}\mathrm{eV}$, in the cosmic ray spectrum.

We revisit the problem of searching for gravitational waves from inspiralling compact binaries in Gaussian colored noise. If the intrinsic parameters of a quasicircular, nonprecessing binary are known, then the optimal statistic for detecting the dominant mode signal in a single interferometer is given by the well-known two-phase matched filter. However, the matched filter signal-to-noise ratio (SNR) is not in general an optimal statistic for an astrophysical population of signals, since their distribution over the intrinsic parameters will almost certainly not mirror that of noise events, which is determined by the (Fisher) information metric. Instead, the optimal statistic for a given astrophysical distribution will be the Bayes factor, which we approximate using the output of a standard template matched filter search. We then quantify the improvement in number of signals detected for various populations of nonspinning binaries: for a distribution of signals uniformly distributed in volume and with component masses distributed uniformly over the range $1\le m_{1,2}/{\mathrm{M}}_{\odot }\le 24$, $(m_1+m_2)/{\mathrm{M}}_{\odot }\le 25$ at fixed expected SNR, we find $\gtrsim 20\%$ more signals at a false alarm threshold of ${10}^{-6}\mathrm{Hz}$ in a single detector. The method may easily be generalized to binaries with nonprecessing spins.

We show that for the active-sterile flavor mixing parameters suggested by the reactor neutrino anomaly, substantial ${\nu }_e\text{−}{\nu }_s$ and ${\overline{\nu }}_e\text{−}{\overline{\nu }}_s$ conversion occurs in regions with an electron fraction of $\approx 1/3$ near the core of an $8.8M_{\odot }$ electron-capture supernova. We explicitly include the feedback of such conversion on the evolution of the electron fraction in supernova ejecta. Compared to the case without such conversion, the neutron richness of the ejecta is enhanced to allow production of elements from Sr, Y, and Zr up to Cd in broad agreement with observations of the metal-poor star HD 122563 for a wide range of mixing parameters. Active-sterile flavor conversion can also strongly suppress neutrino heating at times when it is important for the revival of the shock. Our results suggest that simulations of a supernova explosion and the associated nucleosynthesis may be used to constrain active-sterile mixing parameters in combination with neutrino experiments and cosmological considerations.

We study charmless two-body baryonic $B$ decays using the topological amplitude approach. We extend a previous work to include all ground state octet and decuplet final states with full topological amplitudes. Relations on rates and $CP$ asymmetries are obtained. The number of independent topological amplitudes is significantly reduced in the large $m_B$ asymptotic limit. With the long awaited ${\overline{B}}^0\to p\overline{p}$ data, we can finally extract information on the topological amplitudes and predict rates of all other modes. The predicted rates are in general with uncertainties of a factor of 2 by including corrections to the asymptotic relations and from subleading contributions. We point out some modes that will cascadely decay to all charged final states and have large decay rates. For example, ${\overline{B}}_s^0\to {\mathrm{\Omega }}^{-}\overline{{\mathrm{\Omega }}^{-}}$, $B^{-}\to p\overline{{\mathrm{\Delta }}^{++}}$, $B^{-}\to \mathrm{\Lambda }\overline{p}$ and ${\overline{B}}_s^0\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}$ decays are interesting modes to search for. We find that the ${\overline{B}}^0\to p\overline{p}$ mode is the most accessible one among octet-antioctet final states in the $\mathrm{\Delta }S=0$ transition. It is not surprise that it is the first ${\overline{B}}_q\to \mathcal{B}\overline{\mathcal{B}}$ mode being observed. With the detection of ${\pi }^0$ and/or $\gamma$ many other unsuppressed modes can be searched for. The predicted ${\overline{B}}_s^0\to p\overline{p}$ rate is several order smaller than the present experimental result. The central value of the experimental result can be reproduced only with unnaturally scaled up “subleading contributions,” which will affect other modes including the ${\overline{B}}^0\to p\overline{p}$ decay. We need more data to clarify the situation. The analysis presented in this work can be systematically improved when more measurements on decay rates become available.

In a scenario with heavy supersymmetric sfermions and decoupled supersymmetric Higgs sector, a well-tempered neutralino is the remaining candidate for thermal single-component sub-TeV dark matter. Well-tempered neutralinos are studied in the context of supersymmetric grand unified theories (GUTs) with third family Yukawa coupling unification. A global ${\chi }^2$ analysis is performed, including the observables $M_W$, $M_Z$, $G_F$, ${\alpha }_{\text{em}}^{-1}$, ${\alpha }_s(M_Z)$, $M_t$, $m_b(m_b)$, $M_{\tau }$, $b\to s\gamma$, $\mathrm{BR}(B_s\to {\mu }^{+}{\mu }^{-})$, $M_h$ and $\mathrm{\Omega }{h}^2$. Tensions in simultaneously fitting the Higgs and bottom quark masses while also avoiding gluino mass bounds from the LHC disfavors light Higgsinos with mass $\lesssim 500\mathrm{GeV}$, ruling out light bino/Higgsino dark matter candidates. Bino/wino/Higgsino and bino/wino candidates fare somewhat better although they are fine-tuned and require departure from GUT-scale gaugino mass universality (the example chosen here is the mixed modulus-anomaly pattern). Implications for dark matter direct detection of these models as well as collider signatures are briefly discussed. Independent of the thermal dark matter viability, these models will be severely constrained by the absence of a gluino at the next run of LHC.

In supersymmetric theories, the $R$ symmetry plays a unique role in suppressing a constant term in the superpotential. In single chiral field models of spontaneous breaking of a discrete $R$ symmetry, an $R$-breaking field can be a good candidate for an inflaton in new inflation models. In this paper, we revisit the compatibility of the single-field $R$-breaking new inflation model with the results of the Planck experiment. As a result, we find that the model predicts a lower limit on the gravitino mass, $m_{3/2}>O(100)\mathrm{TeV}$, assuming that the $R$-symmetry breaking is dominantly induced by the inflaton and the inflaton dynamics is not affected by the supersymmetry-breaking sector, which can be guaranteed by symmetry or compositeness of the supersymmetry-breaking sector. This lower limit is consistent with the observed Higgs mass of 126 GeV when the masses of the top squarks are of order the gravitino mass scale. We also show that the baryon asymmetry of the Universe as well as the observed dark matter density can be consistently explained along with the $R$-breaking new inflation model, assuming leptogenesis and that the wino is the lightest supersymmetric particle.

Understanding small neutrino masses in type II seesaw models with TeV scale SM triplet Higgs bosons requires that its coupling with the standard model Higgs doublet $H$ be “dialed” down to be order eV to KeV, which is a hierarchy of a factor of ${10}^{-11}–{10}^{-8}$ with respect to the weak scale. We present a class of SUSY extensions of the type II seesaw model where this dimensionful small coupling is radiatively induced, thus making its smallness natural. Remarkably, in our model, this coupling is vanishing if SUSY is unbroken. Furthermore, in order to radiatively generate the coupling between the Higgs doublets and the triplet in this class of models, exotic matter fields need to be introduced. We discuss in detail one model where neutrino mass is triggered by a finite loop of an exotic vectorlike quark doublet which contains a quark $X$ with electric charge $5/3$ and a top partner $t^{\prime }$. We then discuss in detail the phenomenology of the model, paying special attention to the consequences of the interactions of the the exotic heavy quarks and the scalars of the model. Implications for neutrinoless double beta decay and for the LHC experiments are discussed in detail. Remarkably, in this model, both the seesaw triplet and the heavy quarks can manifest at colliders in a host of different signatures, including some that significantly differ from those of the minimal models. Depending on the choice of the hierarchy of couplings, the decay of the heavy quarks and of the seesaw triplet may be subject to bounds that can be tighter or looser than the bounds from standard LHC searches. Furthermore, we point out a new short-distance contribution to neutrinoless double beta decay mediated by the simultaneous propagation of the type II triplet and exotic fermions. Remarkably, this contribution to the neutrinoless double beta decay is parametrically quite independent from the scale of the generated neutrino mass.

The elastic nuclear recoil signal, being under intense scrutiny by multiple underground experiments, can be interpreted either as coming from the interaction of nuclei with WIMP dark matter or from the scattering of new species of MeV-energy neutrinos. The most promising model for the latter case is a neutrino ${\nu }_b$ that interacts with baryon number and with a flux sourced by the oscillations of regular solar ${}^8\mathrm{B}$ neutrinos. We reanalyze this model in light of the latest experimental results. In contrast to the light-DM interpretation of various tentative positive signals (anomalies) that is now seriously challenged by the negative results of the LUX experiment, the neutrino interpretation remains a viable explanation to most of the anomalies. Considering future prospects, we show that the superCDMS experiment alone, when equipped with Ge and Si detectors, will be able to detect ${\nu }_b$ and discriminate the model from a light DM interpretation. In addition, we also provide the forecast for the new CRESST-II run that now operates with new detectors and diminished backgrounds.

Supersymmetric models with a Dirac gluino have been shown to be considerably less constrained from LHC searches than models with a Majorana gluino. In this paper, we generalize this discussion to models with a ‘mixed gluino,” that acquires both Dirac and Majorana masses, as well as models in which electroweak gauginos contribute to squark production. Our primary interest is the degree of suppression of the cross section for first generation squarks compared with a gluino with a pure Majorana mass. We find that not all Majorana masses are alike—a Majorana mass for the gluino can suppress the squark production cross section, whereas a Majorana mass for the adjoint fermion partner leads to an increased cross section, compared with a pure Dirac gluino. In the presence of electroweak gauginos, squark production can increase by at most a factor of a few above the pure Dirac gluino case when the electroweak gauginos have purely Majorana masses near to the squark masses. This unusual set of gaugino masses is interesting since the usual Higgs quartic coupling would not be suppressed. When the electroweak gaugino masses are much lighter than the squarks, there is a negligible change to the squark production cross section. We explain both of these cases in detail by considering the various subprocesses for squark production at the LHC. Continued searches for squark production with cross sections much smaller than expected in the minimal supersymmetric standard model are absolutely warranted, and we suggest new simplified models to fully characterize the collider constraints.