The Georgi-Machacek (GM) model is one of many beyond Standard Model scenarios with an extended scalar sector that can group under the custodial $\mathrm{SU}(2{)}_{\mathrm{C}}$ symmetry into a fiveplet, a triplet, and two singlets. The heavy charged custodial fiveplet Higgs ${\mathrm{H}}_5^{\pm }$ are typical particles in the GM model that couple to the electroweak gauge bosons, therefore providing a good testing ground for the detection of the ${\mathrm{H}}^{\pm }{\mathrm{W}}^{\mp }\mathrm{Z}$ vertex. The neutral custodial fiveplet Higgs ${\mathrm{H}}_5^0$ in the GM model has the same mass with the ${\mathrm{H}}_5^{\pm }$ and couples to both of the electroweak gauge bosons, ${\mathrm{W}}^{+}{\mathrm{W}}^{-}$ and ZZ. Here, we study the discovery prospects of the exotic scalar bosons ${\mathrm{H}}_5^{\pm }$ and ${\mathrm{H}}_5^0$ at the International Linear Collider(ILC) via the vector boson associated production processes, and discuss two different decay modes for both the charged and neutral scalars. The discovery potential is discussed. Testing the mass degeneracy of charged and neutral scalar bosons in the GM model is also considered.

An approach for relating the nucleon resonances extracted from $\pi N$ reaction data to lattice QCD calculations has been developed by using the finite-volume Hamiltonian method. Within models of $\pi N$ reactions, bare states are introduced to parametrize the intrinsic excitations of the nucleon. We show that the resonance can be related to the probability $P_{N^{*}}(E)$ of finding the bare state, $N^{*}$, in the $\pi N$ scattering states in infinite volume. We further demonstrate that the probability $P_{N^{*}}^V(E)$ of finding the same bare states in the eigenfunctions of the underlying Hamiltonian in finite volume approaches $P_{N^{*}}(E)$ as the volume increases. Our findings suggest that the comparison of $P_{N^{*}}(E)$ and $P_{N^{*}}^V(E)$ can be used to examine whether the nucleon resonances extracted from the $\pi N$ reaction data within the dynamical models are consistent with lattice QCD calculation. We also discuss the measurement of $P_{N^{*}}^V(E)$ directly from lattice QCD. The practical differences between our approach and the approach using the Lüscher formalism to relate LQCD calculations to the nucleon resonance poles embedded in the data are also discussed.

In this work, we study the masses and the two-body strong decay of the $\rho$ and ${\rho }_3$ states below 2 GeV in the framework of the chiral quark model and the ${}^3{P}_0$ models. In the calculations, the wave functions of the particles are obtained numerically by the Gaussian expansion method, and they are applied in the decay calculation. By comparing the results with experimental data, we are trying to identify the exotic states. And it will be helpful to study the structures of $\rho /{\rho }_3$ states.

In view of a recently renewed interest to the production of multiple Higgs bosons, the amplitude for such process at the threshold of $n$ particles is considered. An explicit calculation is done for the loop corrections to the amplitude arising from the interaction with a heavy fermion (e.g., top quark) and also with a heavy scalar. It is shown that such corrections generally break the scaling dependence on the number $n$ and the Higgs self-coupling, which dependence is known from the past studies of models with one field. The correction due to the top quark loop is also found to be numerically large and exceeding that from the self-coupling up to very high $n$.

Quantum speed limits set an upper bound to the rate at which a quantum system can evolve, and as such can be used to analyze the scrambling of information. To this end, we consider the survival probability of a thermofield double state under unitary time evolution which is related to the analytic continuation of the partition function. We provide an exponential lower bound to the survival probability with a rate governed by the inverse of the energy fluctuations of the initial state. Further, we elucidate universal features of the nonexponential behavior at short and long times of evolution that follow from the analytic properties of the survival probability and its Fourier transform, both for systems with a continuous and for systems with a discrete energy spectrum. We find the spectral form factor in a number of illustrative models; notably, we obtain the exact answer in the Gaussian unitary ensemble for any $N$ with excellent agreement with recent numerical studies. We also discuss the relationship of our findings to models of black hole information loss, such as the Sachdev-Ye-Kitaev model dual to ${\mathrm{AdS}}_2$, as well as higher-dimensional versions of AdS/CFT.

Fully coherent all-sky search for gravitational wave (GW) signals from the coalescence of compact object binaries is a computationally expensive task. Approximations, such as semicoherent coincidence searches, are currently used to circumvent the computational barrier with a concomitant loss in sensitivity. We explore the effectiveness of particle swarm optimization (PSO) in addressing this problem. Our results, using a simulated network of detectors with initial LIGO design sensitivities and a realistic signal strength, show that PSO can successfully deliver a fully coherent all-sky search with $<1/10$ the number of likelihood evaluations needed for a grid-based search.

We reinvestigate the recently discovered bifurcation phase transition in causal dynamical triangulations and provide further evidence that it is a higher-order transition. We also investigate the impact of introducing matter in the form of massless scalar fields to causal dynamical triangulations. We discuss the impact of scalar fields on the measured spatial volumes and fluctuation profiles in addition to analyzing how the scalar fields influence the position of the bifurcation transition.

In this paper we study quantum radiation from an evaporating spherically symmetric nonsingular black hole. We used a modified Hayward metric for a description of a nonsingular black hole interior. We assume that the mass parameter of this metric depends on the advanced time, and choose this dependence so that it properly reproduces both black hole formation and its subsequent evaporation. We consider a quantum massless scalar field propagating in this geometry and use two-dimensional approximation for the calculation of the quantum average of the stress-energy tensor in the initial vacuum state. For the calculation of this quantity it is sufficient to find a map between the Killing times $u_{+}$ and $u_{-}$ at the future and past null infinities, established by the propagation of the radial null rays. In this formalism the quantum energy flux at the future null infinity can be expressed in terms of the function $u_{+}(u_{-})$ and its derivatives up to the third order. We developed a special formalism, which allows one to reduce the problem of the calculation of the quantum energy flux and other observables to a solution of a simple set of ordinary differential equations. We used this approach to study quantum effects in two cases: (i) with the trivial, $\alpha =1$, and (ii) the nontrivial, $\alpha \ne 1$, redshift function. We demonstrated that in both cases there exists an outburst of the quantum energy radiation from the inner domain of the black hole, close to the inner part of its apparent horizon. For $\alpha =1$ this outburst is exponentially large. Its appearance is a direct consequence of the so-called mass inflation effect. We also demonstrated that this severe problem can be solved by a proper choice of the redshift function. However, even in this case the emitted energy can be much larger than the initial mass of the evaporating black hole. This means that for a construction of a self-consistent model of a nonsingular evaporating black hole the backreaction effects are highly important.

Residual accelerations due to thermal effects are estimated through a model of the New Horizons spacecraft and a Monte Carlo simulation. We also discuss and estimate the thermal effects on the attitude of the spacecraft. The work is based on a method previously used for the Pioneer and Cassini probes, which solve the Pioneer anomaly problem. The results indicate that after the encounter with Pluto there is a residual acceleration of the order of ${10}^{-9}{\mathrm{m}/\mathrm{s}}^2$, and that rotational effects should be difficult, although not impossible, to detect.

It is widely known that bouncing models with a dust hydrodynamical fluid satisfying $c_s^2=p_d/{\rho }_d\approx 0$, where $c_s$, $p_d$, ${\rho }_d$ are the sound velocity, pressure, and energy density of the dust fluid, respectively, have almost scale invariant spectrum of scalar perturbations and negligible primordial gravitational waves. We investigate whether adding another fluid with $1/3<w=p/\rho <1$, which should dominate near the bounce, can increase the amplitude of gravitational waves in the high frequency regime, turning them detectable in near future observations for such range of frequencies. Indeed, we show that the energy density of primordial gravitational waves is proportional to $k^{2(9w-1)/(1+3w)}$ for wavelengths which become bigger than the Hubble radius when this extra fluid dominates the background. Hence, as $w\to 1$ (an almost stiff matter fluid), the energy density of primordial gravitational waves will increase faster in frequency, turning them potentially detectable at high frequencies. However, there is an extra factor $I_q(w)$ in the amplitude which decreases exponentially with $w$. The net effect of these two contributions turns the energy density of primordial gravitational waves not sufficiently big at high frequencies in order to be detected by present day or near future observations for models which satisfy the nucleosynthesis bounds and is symmetric with respect to the bounce. Hence, symmetric bouncing models where the background is dominated by a dust hydrodynamical fluid with small sound velocity, do not present any significant amount of primordial gravitational waves at any frequency range compatible with observations, even if there are other fields present in the model dominating the bounce phase. Any detection of such waves will then rule out this kind of model.

We introduce a new proposal for the onset of cosmic acceleration based on mass varying neutrinos. When massive neutrinos become nonrelativistic, the $Z_2$ symmetry breaks, and the quintessence potential becomes positive from its initially zero value. This positive potential behaves like a cosmological constant at the present era and drives the Universe’s acceleration during the slow roll evolution of the quintessence. In contrast to $\mathrm{\Lambda }\mathrm{CDM}$ model, the dark energy in our model is dynamical, and the acceleration is not persistent. Contrary to some of the previous models of dark energy with mass varying neutrinos, we do not use the adiabaticity condition, which leads to instability.

We have built sky maps showing the expected arrival directions of 120 EeV ultrahigh-energy cosmic rays (UHECRs) directionally correlated with the latest astrophysical neutrino tracks observed at IceCube, including the four-year high-energy starting events (HESEs) and the two-year northern tracks, taken as point sources. We have considered contributions to UHECR deflections from the Galactic and the extragalactic magnetic field and a UHECR composition compatible with the current expectations. We have used the Jansson-Farrar JF12 model for the Galactic magnetic field and an extragalactic magnetic field strength of 1 nG and coherence length of 1 Mpc. We observe that the regions outside of the Galactic plane are more strongly correlated with the neutrino tracks than those adjacent to or in it, where IceCube HESE events 37 and 47 are good candidates to search for excesses, or anisotropies, in the UHECR flux. On the other hand, clustered northern tracks around $(l,b)=(0°,-30°)$ and $(l,b)=(-150°,-30°)$ are promising candidates for a stacked point source search. For example, we have focused on the region of UHECR arrival directions, at 150 EeV, correlated with IceCube HESE event 37 located at $(l,b)=(-137.1°,65.8°)$ in the northern hemisphere, far away from the Galactic plane, obtaining an angular size $\sim 5°$, being $\sim 3°$ for 200 EeV and $\sim 8°$ for 120 EeV. We report a p value of 0.20 for a stacked point source search using current Auger and Telescope Array data, consistent with current results from both collaborations. Using Telescope Array data alone, we found a projected live time of 72 years to find correlations, but clearly this must improve with the planned Auger upgrade.

For models in which dark matter annihilation is Sommerfeld-enhanced, the annihilation cross section increases at low relative velocities. Dwarf spheroidal galaxies (dSphs) have low characteristic dark matter particle velocities and are thus ideal candidates to study such models. In this paper, we model the dark matter phase space of dSphs as isotropic and spherically symmetric and determine the $J$ factors for several of the most important targets for indirect dark matter searches. For Navarro-Frenk-White density profiles, we quantify the scatter in the $J$ factor arising from the astrophysical uncertainty in the dark matter potential. We show that, in Sommerfeld-enhanced models, the ordering of the most promising dSphs may be different relative to the standard case of velocity-independent cross sections. This result can have important implications for derived upper limits on the annihilation cross section, or on possible signals, from dSphs.

Coy dark matter is an effective scheme in which a fermionic dark matter candidate interacts with the standard model fermions via a pseudoscalar mediator. This simple setup avoids the strong constraints posed by direct detection experiments in a natural way and explains, on top of the observed dark matter relic abundance, the spatially extended $\gamma$-ray excess recently detected at the Galactic Center. In this paper we study the phenomenology of coy dark matter accounting for a novel signature of the model: the diphoton annihilation signal induced by the standard model fermions at the loop level. By challenging the model with the observations of spheroidal dwarf satellite galaxies and the results of $\gamma$-ray line searches obtained by the Fermi LAT experiment, we assess its compatibility with the measured dark matter relic abundance and the Galactic Center excesses. We show that despite the $\gamma$-ray line constraint rules out a significant fraction of the considered parameter space, the region connected to the observed Galactic Center excess remains currently viable. Nevertheless, we find that next-generation experiments such as DAMPE, HERD and GAMMA-400 have the potential to probe exhaustively this elusive scenario.

We demonstrate that the geometric volume of a soliton coincides with the thermodynamical volume also for field theories with higher-dimensional vacuum manifolds (e.g., for gauged scalar field theories supporting vortices or monopoles), generalizing the recent results of Ref. [C. Adam, M. Haberichter, and A. Wereszczynski, Phys. Lett. B 754, 18 (2016).]. We apply this observation to understand Bradlow-type bounds for general Abelian gauge theories supporting vortices, as well as some thermodynamical aspects of said theories. In the case of SDiff Bogomolny-Prasad-Sommerfield (BPS) models (being examples of perfect fluid models) we show that the base-space independent geometric volume (area) of the vortex is exactly equal to the Bradlow volume (a minimal volume for which BPS soliton solutions exist). This volume can be finite for compactons or infinite for infinitely extended solitons (in flat Minkowski space-time).

We investigate the lower bounds of sfermion masses from the constraints of chromoelectric dipole moments (CEDMs) in the natural SUSY-type sfermion mass spectrum, in which stop mass $m_{\tilde{t}}$ is much smaller than the other sfermion masses $m_0$. The natural SUSY-type sfermion mass spectrum has been studied since the supersymmetric (SUSY) flavor-changing neutral currents (FCNC) are suppressed because of large sfermion masses of the first two generations, and the weak scale is stabilized because of the light stop. However, this type of sfermion mass spectrum is severely constrained by CEDM, because the light stop contributions to the up quark CEDM are not decoupled in the limit $m_0\to \infty$, while the down quark CEDM is decoupled in the limit. It is important that the constraints are severe even if SUSY-breaking parameters (and Higgsino mass) are taken to be real because complex diagonalizing matrices of Yukawa matrices, which are from complex Yukawa couplings, generate nonvanishing $CP$ phases in off-diagonal elements of sfermion mass matrices. We calculate the CEDM of up and down quarks numerically in the minimal SUSY standard model, and give the lower bounds for stop mass and the other sfermion masses. We show that the lower bound of stop mass becomes 7 TeV to satisfy the CEDM constraints from Hg EDM. The result is not acceptable if the weak scale stability is considered seriously. We show that if the up-type Yukawa couplings are taken to be real at the grand unification scale, the CEDM constraints are satisfied even if $m_{\tilde{t}}\sim 1\mathrm{TeV}$.

Heavy sterile neutrinos with masses below $M_W$ can induce trilepton events at the 14 TeV LHC through purely leptonic $W$ decays of $W^{\pm }\to e^{\pm }{e}^{\pm }{\mu }^{\mp }\nu$ and ${\mu }^{\pm }{\mu }^{\pm }{e}^{\mp }\nu$ where the heavy neutrino will be in an intermediate state on its mass shell. Discovery and exclusion limits for the heavy neutrinos are found using both cut-and-count (CC) and multivariate analysis (MVA) methods in this study. We also show that it is possible to discriminate between a Dirac and a Majorana heavy neutrino, even when lepton number conservation cannot be directly tested due to unobservability of the final state neutrino. This discrimination is done by exploiting a combined set of kinematic observables that differ between the Majorana and Dirac cases. We find that the MVA method can greatly enhance the discovery and discrimination limits in comparison with the CC method. For a 14-TeV $pp$ collider with integrated luminosity of $3000{\mathrm{fb}}^{-1}$, sterile neutrinos can be found with $5\sigma$ significance if heavy-to-light neutrino mixings $|U_{Ne}{|}^2\sim |U_{N\mu }{|}^2\sim {10}^{-6}$, while the Majorana vs Dirac type can be distinguished if $|U_{Ne}{|}^2\sim |U_{N\mu }{|}^2\sim {10}^{-5}$ or even $|U_{N\ell }{|}^2\sim {10}^{-6}$ if one of the mixing elements is at least an order of magnitude smaller than the other.

The scalar potential of the two-Higgs-doublet model may have more than one local minimum and the usually considered vacuum could be located at one of them that could decay to another. This paper studies the condition that the usually considered vacuum is the global minimum which, combined with the bounded-from-below condition, will stabilize the vacuum at tree level. We further apply these conditions to a specific two-Higgs-doublet model and obtain new constraints which could be important in phenomenological studies.

We report the most general expression for the chiral charges of a nonuniversal $U(1{)}^{\prime }$ with identical charges for the first two families but different charges for the third one. The model is minimal in the sense that only standard model fermions plus right-handed neutrinos are required. By imposing anomaly cancellation and constraints coming from Yukawa couplings, we obtain two different solutions. In one of these solutions, the anomalies cancel between fermions in different families. These solutions depend on four independent parameters which result very useful for model building. We build different benchmark models in order to show the flexibility of the parametrization. We also report LHC and low energy constraints for these benchmark models.