We study Higgs inflation in the context of generalized $G$-inflation, i.e., the most general single-field inflation model with second-order field equations. The four variants of Higgs inflation proposed so far in the literature can be accommodated at one time in our framework. We also propose yet another class of Higgs inflation, the running Einstein inflation model, that can naturally arise from the generalized $G$-inflation framework. As a result, five Higgs inflation models in all should be discussed on an equal footing. Concise formulas for primordial fluctuations in these generalized Higgs inflation models are provided, which will be helpful to determine which model is favored from the future experiments and observations such as the Large Hadron Collider and the Planck satellite.

Gravitational waves (GWs) are one of the key signatures of cosmic strings. If GWs from cosmic strings are detected in future experiments, not only their existence can be confirmed, but also their properties might be probed. In this paper, we study the determination of cosmic string parameters through direct detection of GW signatures in future ground-based GW experiments. We consider two types of GWs, bursts and the stochastic GW background, which provide us with different information about cosmic string properties. Performing the Fisher matrix calculation on the cosmic string parameters, such as parameters governing the string tension $G\mu$ and initial loop size $\alpha$ and the reconnection probability $p$, we find that the two different types of GWs can break degeneracies in some of these parameters and provide better constraints than those from each measurement.

We explore the prospects for constraining cosmology using gravitational-wave (GW) observations of neutron-star binaries by the proposed Einstein Telescope (ET), exploiting the narrowness of the neutron-star mass function. This builds on our previous work in the context of advanced-era GW detectors. Double neutron-star (DNS) binaries are expected to be one of the first sources detected after “first-light” of Advanced LIGO. DNS systems are expected to be detected at a rate of a few tens per year in the advanced era, but the proposed ET could catalog tens, if not hundreds, of thousands per year. Combining the measured source redshift distributions with GW-network distance determinations will permit not only the precision measurement of background cosmological parameters, but will provide an insight into the astrophysical properties of these DNS systems. Of particular interest will be to probe the distribution of delay times between DNS-binary creation and subsequent merger, as well as the evolution of the star-formation rate density within ET’s detection horizon. Keeping $H_0$, ${\Omega }_{m,0}$ and ${\Omega }_{\Lambda ,0}$ fixed and investigating the precision with which the dark-energy equation-of-state parameters could be recovered, we found that with ${10}^5$ detected DNS binaries, we could constrain these parameters to an accuracy similar to forecasted constraints from future $\mathrm{CMB}+\mathrm{BAO}+\mathrm{SNIa}$ measurements. Furthermore, modeling the merger delay-time distribution as a power-law ($\propto t^{\alpha }$) and the star-formation rate density as a parametrized version of the Porciani and Madau SF2 model, we find that the associated astrophysical parameters are constrained to within $\sim 10\%$. All parameter precisions scaled as $1/\sqrt{N}$, where $N$ is the number of cataloged detections. We also investigated how parameter precisions varied with the intrinsic underlying properties of the Universe and with the distance reach of the network (which is affected, for instance, by the low-frequency cutoff of the detector). We also consider various sources of distance-measurement errors in the third-generation era and how these can be folded into the analysis.

The typical scalar field theory has a cosmological constant problem. We propose a generic mechanism by which this problem is avoided at tree level by embedding the theory into a larger theory. The metric and the scalar field coupling constants in the original theory do not need to be fine-tuned, while the extra scalar field parameters and the metric associated with the extended theory are fine-tuned dynamically. Hence, no fine-tuning of parameters in the full Lagrangian is needed for the vacuum energy in the new physical system to vanish at tree level. The cosmological constant problem can be solved if the method can be extended to quantum loops.

We prove that sign problems in the traditional approach to some lattice Yukawa models can be completely solved when fermions are formulated using fermion bags and bosons are formulated in the worldline representation. We prove this within the context of two examples of three-dimensional models, symmetric under $U_L(1)\times U_R(1)\times Z_2(\mathrm{\text{parity}})$ transformations, one involving staggered fermions and the other involving Wilson fermions. We argue that these models have interesting quantum phase transitions that can now be studied using Monte Carlo methods.

We study quasistationary physical process for black holes within the context of Lanczos-Lovelock gravity. We show that the Wald entropy of the stationary black holes in Lanczos-Lovelock gravity monotonically increases for quasistationary physical processes in which the horizon is perturbed by the accretion of positive energy matter and the black hole ultimately settles down to a stationary state. This result reinforces the physical interpretation of Wald entropy for Lanczos-Lovelock models and takes a step towards proving the analogue of the black hole area increase theorem in a wider class of gravitational theories.

A combined expansion in the number of QCD colors $1/N_c$ and SU(3) flavor-breaking parameter $ϵ$ has long been known to provide an excellent accounting for the mass spectrum of the lightest spin-$\frac{1}{2}$, $\frac{3}{2}$ baryons when the quarks are taken to transform under the fundamental $\mathrm{SU}(N_c)$ representation, and in the final step $N_c\to 3$ and $ϵ$ is set to its physical value $\sim 0.3$. Subsequent work shows that placing quarks in the two-index antisymmetric $\mathrm{SU}(N_c)$ representation leads to quantitatively equally successful mass relations. Recent lattice simulations allow for varying the value of $ϵ$ and confirm the robustness of the original $1/N_c$ relations. In this paper we show that the same conclusion holds for the antisymmetric quarks and demonstrate that the mass relations also hold under alternate prescriptions for identifying physical baryons with particular members of the large $N_c$ multiplets.

Dark matter (DM) has been searched for at colliders in a largely model-independent fashion by looking for an excess number of events involving a single jet, or photon, and missing energy. We investigate the possibility of looking for excesses in more inclusive jet channels. Events with multiple jets contain more information and thus more handles to increase the signal-to-background ratio. In particular, we adapt the recent CMS “razor” analysis from a search for supersymmetry (SUSY) to a search for DM and estimate the potential reach. The region of razor variables which are most sensitive to dark matter are not covered by the current SUSY search. We consider simplified models where DM is a Dirac fermion that couples to the quarks of the standard model (SM) through exchange of vector or axial-vector mediators or to gluons through scalar exchange. We consider both light and heavy (leading to effective contact interactions) mediators. Since the razor analysis requires multiple jets in the final state, the data set is complementary to that used for the monojet search and thus the bounds can be combined.

We study possible anomaly-free discrete $R$ symmetries that avoid the $\mu$ problem and the dangerous $D\le 5$ operators considering charge assignments that do not commute with the traditional grand unifying simple groups, such as $SU(5)$ or $SO(10)$, but commute instead with the so-called flipped $SU(5)$, with or without the operation of the Green-Schwarz (GS) mechanism. We find ${\mathcal{Z}}_N^{(R)}$ symmetries with $N=3$, 6 in the anomaly-free case or $N=3$, 4, 6, 8, 12, 24 in the case of anomaly cancellation through the Green-Schwarz mechanism. Nonunified cases (${\mathcal{Z}}_5$) are also discussed. We also confront the construction of a 4D grand unified flipped model endowed with ${\mathcal{Z}}_N^{(R)}$ and find phenomenologically acceptable solutions with $N=2k+7$ and $N=2k+10$.

Limits on an exotic heavy quark $T$ are broadly generalized by considering the full range of $T\to Wb$, $th$ or $tZ$ branching ratios. We combine results of specific $T\to tZ$ and $T\to Wb$ searches with limits on various combinations of decay modes evaluated by reinterpreting other searches. We find strong bounds across the entire space of branching ratios, ranging from $m_T>415\mathrm{GeV}$ to $m_T>557\mathrm{GeV}$ at 95% confidence level.

The two Higgs bidoublet left-right symmetric model (2HBDM) as a simple extension of the minimal left-right symmetric model with a single Higgs bidoublet is motivated to realize both spontaneous parity ($P$) violation and charge conjugation and parity ($CP$) violation while consistent with the low-energy phenomenology without significant fine-tuning. By carefully investigating the Higgs potential of the model, we find that sizable $CP$-violating phases are allowed after the spontaneous symmetry breaking. The mass spectra of the extra scalars in the 2HBDM are significantly different from the ones in the minimal left-right symmetric model. In particular, we demonstrate in the decoupling limit when the right-handed gauge-symmetry-breaking scale is much higher than the electroweak scale, the 2HBDM decouples into the general two Higgs doublet model with spontaneous $CP$ violation and has rich induced sources of $CP$ violation. We show that in the decoupling limit, it contains extra light Higgs bosons with masses around electroweak scale, which can be directly searched at the ongoing LHC and future International Linear Collider experiments.

We compute the electroweak $S$ and $T$ parameters induced by $SU(2{)}_L$ triplet scalars up to one-loop order. We consider the most general renormalizable potential for a triplet and the Standard Model Higgs doublet. Our calculation is performed by integrating out the triplet at the one-loop level and also includes the one-loop renormalization group running. Effective field theory framework allows us to work in the phase with unbroken $SU(2{)}_L\times U(1{)}_Y$ symmetry. Both $S$ and $T$ parameters exhibit decoupling when all dimensionful parameters are large while keeping dimensionless ratios fixed. We use bounds on $S$ and $T$ to constrain the triplet mass and couplings.

We define a Higgs descendant $\chi$ to be a particle beyond the standard model whose mass arises predominantly from the vacuum expectation value of the Higgs boson. Higgs descendants arise naturally from new physics whose intrinsic mass scale is unrelated to the electroweak scale. The coupling of $\chi$ to the Higgs boson is fixed by the mass and spin of $\chi$, yielding a highly predictive setup in which there may be substantial modifications to the properties of the Higgs boson. For example, if the decay of the Higgs boson to $\chi$ is kinematically allowed, then this branching ratio is largely determined. Depending on the stability of $\chi$, Higgs decays may result in a variety of possible visible or invisible final states. Alternatively, loops of $\chi$ may affect Higgs boson production or its decays to standard model particles. If $\chi$ is stable dark matter, then the mandatory coupling between $\chi$ and the Higgs boson gives a lower bound on the direct detection cross section as a function of the $\chi$ mass. We also present a number of explicit models which are examples of Higgs descendants. Finally, we comment on Higgs descendants in the context of the excesses near 125 GeV recently observed at ATLAS and CMS.

We analyze canonical determinants, i.e., grand canonical determinants projected to a fixed net quark number. The canonical determinants are the coefficients in a fugacity expansion of the grand canonical determinant, and we evaluate them as the Fourier moments of the grand canonical determinant with respect to imaginary chemical potential, using a dimensional reduction technique. The analysis is done for two mass-degenerate flavors of Wilson fermions at several temperatures below and above the confinement/deconfinement crossover. We discuss various properties of the canonical determinants and analyze the convergence of the fugacity series for different temperatures.

We study the wave functions of light and heavy mesons in both hard-wall (HW) and soft-wall (SW) holographic models which use AdS/CFT correspondence. In the case of massless constituents, the asymptotic behaviors of the electromagnetic form factor, the distribution amplitudes, and the decay constants for the two models are the same, if the relation between the dilaton scale parameter and the size of meson is an inverse proportion. On the other hand, by introducing a quark mass dependence in the wave function, the differences of the distribution amplitudes between the two models are obvious. In addition, for the SW model, the dependences of the decay constants of meson on the dilaton scale parameter $\kappa$ differ; especially $f_{Qq}\sim {\kappa }^3/m_Q^2$ is consistent with the prediction of the heavy quark effective theory if $\kappa \sim m_Q^{1/2}$. Thus the parameters of the two models are fit by the decay constants of the distinct mesons; the distribution amplitudes and the $\xi$-moments are calculated and compared.

The widths of the decays ${\rho }^{-}\to \eta {\pi }^{-}$ and ${\tau }^{-}\to \eta ({\eta }^{\prime }){\pi }^{-}\nu$ are calculated in the framework of the Nambu–Jona-Lasinio model. It is shown that these decays are defined by the $u$ and $d$ quark mass difference. It leads to the suppression of these decays in comparison with the main decay modes. In the process ${\rho }^{-}\to \eta {\pi }^{-}$ the intermediate scalar $a_0^{-}$ state is taken into account. For the $\tau$ decays the intermediate states with $a_0^{-}$, ${\rho }^{-}(770)$ and ${\rho }^{-}(1450)$ mesons are used. Our estimates are compared with the results obtained in other works.

According to supersimplicity in MSSM, a renormalization scheme (SRS) may be defined for any high-energy 2-to-2 process, to the 1loop EW order; where the helicity conserving (HC) amplitudes, are expressed as a linear combination of just three universal logarithm-involving forms. All other helicity amplitudes vanish asymptotically. Including to these SRS amplitudes the corresponding counterterms, the supersimple expressions for the high-energy HC amplitudes, renormalized on-shell, are obtained. Previously, this property was noted for a large number of processes that do not involve Yukawa interactions or renormalization group corrections. Here we extend this to $e^{-}{e}^{+}\to t\overline{t}$, which does involve large Yukawa and renormalization group contributions. We show that the resulting supersimple expressions may provide an accurate description, even at energies comparable to the SUSY scale. Such descriptions clearly identify the origin of the important SUSY effects, and they may be used for quickly constraining physics contributions, beyond MSSM.

We discuss the seesaw mechanism which includes the minimum number of parameters for successful leptogenesis and three neutrino oscillations in the spirit of Occam’s razor. We show that models with two right-handed neutrinos with two texture zeros supported by Occam’s razor cannot fit the observed neutrino parameters consistently for the normal light neutrino mass hierarchy. For the inverted light neutrino mass hierarchy, on the other hand, we find that the models can fit the observed neutrino parameters consistently. Besides, we show that the model predicts the maximal Dirac $CP$-phase of the neutrino mixing matrix in the measurable range in the foreseeable future for the inverted neutrino mass hierarchy. We also show that the predicted effective Majorana neutrino mass responsible for the neutrinoless double beta decay is around 50 meV which is also within reach of future experiments.

We report a study of the decay $B^0\to D{K}^{+}{\pi }^{-}$ followed by $D\to K^{-}{\pi }^{+}$, where $D$ indicates $D^0$ or ${\overline{D}}^0$. We reconstruct the $D{K}^{+}{\pi }^{-}$ state in a phase space corresponding to $D{K}^{*}(892{)}^0$. The $CP$-violating angle ${\varphi }_3$ affects its decay rate via the interference between $b\to u$ and $b\to c$ transitions. The result is obtained from a $711{\mathrm{fb}}^{-1}$ data sample that contains $772\times {10}^{6}B\overline{B}$ pairs collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We measure the ratio ${\mathcal{R}}_{D{K}^{*0}}\equiv \Gamma (B^0\to [K^{-}{\pi }^{+}{]}_D{K}^{+}{\pi }^{-})/\Gamma (B^0\to [K^{+}{\pi }^{-}{]}_D{K}^{+}{\pi }^{-})$ to be $({4.5}_{-5.0-1.8}^{+5.6+2.8})\times {10}^{-2}$, and set an upper limit of ${\mathcal{R}}_{D{K}^{*0}}<0.16$ at the 95% credible interval.

We explore the photoemission rate and conductivity in dense QCD by taking the AdS/CFT methods. Specifically, we take three QCD gravity dual models to do comparative studies: D4/D6 model, noncritical Sakai-Sugimoto model and soft-wall AdS/QCD model. We turn on the time component of flavor U(1) gauge field in the bulk side to model the baryon density in QCD. For all three models, we numerically solve the U(1) fluctuation equation to plot the spectral function and photoemission rate for lightlike momenta as well as the AC conductivity. We find that the results for the former two models are very similar to previous studies while the last one show some differences. The conductivity in the soft-wall model seems to be similar to that of holographic superconductor constructed from five-dimensional bulk gravity, i.e. the pseudogap structure. This should be owing to that the infrared (IR) soft-wall (an effective cutoff near the IR of the geometry) produces a mass gap in the dual field theory, which has imprinting in the conductivity as a pseudogap formation. However, the DC conductivity in our computations is finite while it should be a delta peak in holographic superconductor models. Our results show the importance of dilaton running in affecting physical quantities.