Nontrivial algebra structures of the coordinate and momentum operators are potentially important for describing possible new physics. The persistent charged current in a metal ring is expected to be sensitive to the nontrivial dynamics due to noncommutativities of phase space. In this paper, we propose a new asymmetric observable for probing the noncommutativity of momentum operators. We also analyzed the temperature dependence of this observable, and we find that the asymmetry holds at a finite temperature. The critical temperature, above which the correction due to coordinate noncommutativity is negligible, is also derived.

We study topological defects in the Georgi-Machacek model in a hierarchical symmetry breaking in which extra triplets acquire vacuum expectation values before the doublet. We find a possibility of topologically stable non-Abelian domain walls and non-Abelian flux tubes (vortices or cosmic strings) in this model. In the limit of the vanishing $U(1{)}_{\mathrm{Y}}$ gauge coupling in which the custodial symmetry becomes exact, the presence of a vortex spontaneously breaks the custodial symmetry, giving rise to $S^2$ Nambu-Goldstone (NG) modes localized around the vortex corresponding to non-Abelian fluxes. Vortices are continuously degenerated by these degrees of freedom, thereby called non-Abelian. By taking into account the $U(1{)}_{\mathrm{Y}}$ gauge coupling, the custodial symmetry is explicitly broken, the NG modes are lifted to become pseudo-NG modes, and all non-Abelian vortices fall into a topologically stable $Z$ string. This is in contrast to the standard model in which $Z$ strings are nontopological and are unstable in the realistic parameter region. Non-Abelian domain walls also break the custodial symmetry and are accompanied by localized $S^2$ NG modes. Finally, we discuss the existence of domain wall solutions bounded by flux tubes, where their $S^2$ NG modes match. The domain walls may quantum mechanically decay by creating a hole bounded by a flux tube loop, and would be cosmologically safe. Gravitational waves produced from unstable domain walls could be detected by future experiments.

We study the possibility of generating nonzero reactor mixing angle ${\theta }_{13}$ and baryon asymmetry of the Universe within the framework of an $A_4$ flavor symmetric model. Using the conventional type I seesaw mechanism we construct the Dirac and Majorana mass matrices that give rise to the correct light neutrino mass matrix. Keeping the right-handed neutrino mass matrix structure trivial so that it gives rise to a (quasi) degenerate spectrum of heavy neutrinos suitable for resonant leptogenesis at TeV scale, we generate the nontrivial structure of Dirac neutrino mass matrix that can lead to the light neutrino mixing through the type I seesaw formula. Interestingly, such a setup naturally leads to nonzero ${\theta }_{13}$ due to the existence of antisymmetric contraction of the product of two triplet representations of $A_4$. Such an antisymmetric part of the triplet products usually vanishes for right-handed neutrino Majorana mass terms, leading to $\mu -\tau$ symmetric scenarios in the most economical setups. We constrain the model parameters from the requirement of producing the correct neutrino data as well as baryon asymmetry of the Universe for right-handed neutrino mass scale around TeV. The $A_4$ symmetry is augmented by additional $Z_3\times Z_2$ symmetry to make sure that the splitting between right-handed neutrinos required for resonant leptogenesis is generated only by next to leading order terms, making it naturally small. We find that the inverted hierarchical light neutrino masses give more allowed parameter space consistent with neutrino and baryon asymmetry data.

We consider the baryogenesis picture in the Zee-Babu model. Our analysis shows that electroweak phase transition (EWPT) in the model is a first-order phase transition at the 100 GeV scale, its strength ranges from 1 to 4.15 and the masses of charged Higgs boson are smaller than 300 GeV. The EWPT is strengthened by only the new bosons and this strength is enhanced by arbitrary $\xi$ gauge. However, the $\xi$ gauge does not break the first-order EWPT or, in other words, the $\xi$ gauge is not the cause of the EWPT. This leads to the fact that the calculation of EWPT in Landau gauge is enough; and the latter may provide baryon-number violation (B-violation) necessary for baryogenesis in the relationship with nonequilibrium physics in the early universe.

We use lattice simulations to compute the baryon spectrum of SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. This model is closely related to a composite Higgs model in which the chimera baryon made up of fermions from both representations plays the role of a composite top-quark partner. The dependence of the baryon masses on each underlying fermion mass is found to be generally consistent with a quark-model description and large-$N_c$ scaling. We combine our numerical results with experimental bounds on the scale of the new strong sector to estimate a lower bound on the mass of the top-quark partner. We discuss some theoretical uncertainties associated with this estimate.

This paper focuses on hadron mass effects in calculations of semi-inclusive kaon production in lepton-Deuteron deeply inelastic scattering at HERMES and COMPASS kinematics. In the collinear factorization framework, the corresponding cross section is shown to factorize, at leading order and leading twist, into products of parton distributions and fragmentation functions evaluated in terms of kaon- and nucleon-mass-dependent scaling variables, and to respect gauge invariance. It is found that hadron mass corrections for integrated kaon multiplicities sizeably reduce the apparent large discrepancy between measurements of $K^{+}+K^{-}$ multiplicities performed by the two collaborations, and fully reconcile their $K^{+}/K^{-}$ ratios.

Adopting the one-boson-exchange model, we perform a systematic investigation of interactions between a doubly charmed baryon $({\mathrm{\Xi }}_{cc})$ and an $S$-wave charmed baryon (${\mathrm{\Lambda }}_c$, ${\mathrm{\Sigma }}_c^{(*)}$, and ${\mathrm{\Xi }}_c^{(\prime ,*)}$). Both the $S-D$ mixing effect and coupled-channel effect are considered in this work. Our results suggest that there may exist several possible triple-charm deuteronlike hexaquarks. Meanwhile, we further study the interactions between a doubly charmed baryon and an $S$-wave anticharmed baryon. We find that a doubly charmed baryon and an $S$-wave anticharmed baryon can be easily bound together to form shallow molecular hexaquarks. These heavy flavor hexaquarks predicted here can be accessible at future experiment like LHCb.

In the spectator models of the nucleon with scalar and axial-vector diquarks, we show the effect of Pauli coupling in the photon-quark vertex to the parton distribution functions (PDFs) of nucleon and azimuthal asymmetry in the unpolarized semi-inclusive deep inelastic scattering (SIDIS). This anomalous coupling gives an obvious contribution to unpolarized and polarized PDFs and also leads to a $\cos 2{\varphi }_h$ azimuthal asymmetry proportional to the squared Pauli form factor, due to the helicity flip of the struck quark. After determining the model parameters by fitting PDFs to the global fits, this new distribution for $\cos 2{\varphi }_h$ asymmetry is given numerically. In the framework of transverse momentum dependence (TMD), we find that it is positive and of a few percent in the kinematical regime of HERMES and COMPASS Collaborations, in the same order of magnitude as the Cahn effect.

The self-consistent chiral quark-soliton model is a relativistic pion mean-field approach in the large $N_c$ limit, which describes both light and heavy baryons on an equal footing. In the limit of the infinitely heavy mass of the heavy quark, a heavy baryon can be regarded as $N_c-1$ valence quarks bound by the pion mean fields, leaving the heavy quark as a color static source. The structure of the heavy baryon in this scheme is mainly governed by the light-quark degrees of freedom. Based on this framework, we evaluate the electromagnetic form factors of the lowest-lying heavy baryons. The rotational $1/N_c$ and strange current quark mass corrections in linear order are considered. We discuss the electric charge and magnetic densities of heavy baryons in comparison with those of the nucleons. The results of the electric charge radii of the positive-charged heavy baryons show explicitly that the heavy baryon is a compact object. The electric form factors are presented. The form factor of ${\mathrm{\Sigma }}_c^{++}$ is compared with that from a lattice QCD. We also discuss the results of the magnetic form factors. The magnetic moments of the baryon sextet with spin $1/2$ and the magnetic radii are compared with other works and the lattice data.

Partial-wave analysis is an important tool for analyzing large data sets in hadronic decays of light and heavy mesons. It commonly relies on the isobar model, which assumes multihadron final states originate from successive two-body decays of well-known undisturbed intermediate states. Recently, analyses of heavy-meson decays and diffractively produced states have attempted to overcome the strong model dependences of the isobar model. These analyses have overlooked that model-independent, or freed-isobar, partial-wave analysis can introduce mathematical ambiguities in results. We show how these ambiguities arise and present general techniques for identifying their presence and for correcting for them. We demonstrate these techniques with specific examples in both heavy-meson decay and pion–proton scattering.

We perform threshold resummation of soft gluon corrections to the total cross section and the invariant mass distribution for the process $pp\to t\overline{t}H$. The resummation is carried out at next-to-next-to-leading-logarithmic (NNLL) accuracy using the direct QCD Mellin space technique in the three-particle invariant mass kinematics. After presenting analytical expressions we discuss the impact of resummation on the numerical predictions for the associated Higgs boson production with top quarks at the LHC. We find that next-to-leading-order (NLO)+NNLL resummation leads to predictions for which the central values are remarkably stable with respect to scale variation and for which theoretical uncertainties are reduced in comparison to NLO predictions.

The classical $B=5$ Skyrmion can be approximated by a two-cluster system in which a $B=1$ Skyrmion is attached to a core $B=4$ Skyrmion. We quantize this system, allowing the $B=1$ to freely orbit the core. The configuration space is 11 dimensional but simplifies significantly after factoring out the overall spin and isospin degrees of freedom. We exactly solve the free quantum problem and then include an interaction potential between the Skyrmions numerically. The resulting energy spectrum is compared to the corresponding nuclei—the helium-5/lithium-5 isodoublet. We find approximate parity doubling not seen in the experimental data. In addition, we fail to obtain the correct ground-state spin. The framework laid out for this two-cluster system can readily be modified for other clusters and in particular for other $B=4n+1$ nuclei, of which $B=5$ is the simplest example.

Basis tensor gauge theory (BTGT) is a reformulation of ordinary gauge theory that is an analog of the vierbein formulation of gravity and is related to the Wilson line formulation. To match ordinary gauge theories coupled to matter, the BTGT formalism requires a continuous symmetry that we call the BTGT symmetry in addition to the ordinary gauge symmetry. After classically interpreting the BTGT symmetry, we construct using the BTGT formalism the Ward identities associated with the BTGT symmetry and the ordinary gauge symmetry. For a way of testing the quantum stability and the consistency of the Ward identities with a known regularization method, we explicitly renormalize the scalar QED at one loop using dimensional regularization using the BTGT formalism.

We study the horizon geometry of Kerr black holes (BHs) with scalar synchronized hair [1], a family of solutions of the Einstein-Klein-Gordon system that continuously connects to vacuum Kerr BHs. We identify the region in parameter space wherein a global isometric embedding in Euclidean 3-space, ${\mathbb{E}}^3$, is possible for the horizon geometry of the hairy BHs. For the Kerr case, such embedding is possible iff the horizon dimensionless spin $j_H$ (which equals the total dimensionless spin, $j$), the sphericity $\mathfrak{s}$ and the horizon linear velocity $v_H$ are smaller than critical values, $j^{(\mathrm{S})},{\mathfrak{s}}^{(\mathrm{S})},v_H^{(\mathrm{S})}$, respectively. For the hairy BHs, we find that $j_H<j^{(\mathrm{S})}$ is a sufficient, but not necessary, condition for being embeddable; $v_H<v_H^{(\mathrm{S})}$ is a necessary, but not sufficient, condition for being embeddable; whereas $\mathfrak{s}<{\mathfrak{s}}^{(\mathrm{S})}$ is a necessary and sufficient condition for being embeddable in ${\mathbb{E}}^3$. Thus, the latter quantity provides the most faithful diagnosis for the existence of an ${\mathbb{E}}^3$ embedding within the whole family of solutions. We also observe that sufficiently hairy BHs are always embeddable, even if $j$—which for hairy BHs (unlike Kerr BHs) differs from $j_H$—is larger than unity.

A large number of theoretically predicted waveforms are required by matched-filtering searches for the gravitational-wave signals produced by compact binary coalescence. In order to substantially alleviate the computational burden in gravitational-wave searches and parameter estimation without degrading the signal detectability, we propose a novel reduced-order-model (ROM) approach with applications to adiabatic 3PN-accurate inspiral waveforms of nonspinning sources that evolve on either highly or slightly eccentric orbits. We provide a singular-value decomposition-based reduced-basis method in the frequency domain to generate reduced-order approximations of any gravitational waves with acceptable accuracy and precision within the parameter range of the model. We construct efficient reduced bases comprised of a relatively small number of the most relevant waveforms over three-dimensional parameter-space covered by the template bank (total mass $2.15M_{\odot }\le M\le 215M_{\odot }$, mass ratio $0.01\le q\le 1$, and initial orbital eccentricity $0\le e_0\le 0.95$). The ROM is designed to predict signals in the frequency band from 10 Hz to 2 kHz for aLIGO and aVirgo design sensitivity. Beside moderating the data reduction, finer sampling of fiducial templates improves the accuracy of surrogates. Considerable increase in the speedup from several hundreds to thousands can be achieved by evaluating surrogates for low-mass systems especially when combined with high-eccentricity.

We study the implications of the recent detection of gravitational waves emitted by a pair of merging neutron stars and their electromagnetic counterpart, events GW170817 and GRB170817A, on the viability of the doubly coupled bimetric models of cosmic evolution, where the two metrics couple directly to matter through a composite, effective metric. We demonstrate that the bounds on the speed of gravitational waves place strong constraints on the doubly coupled models, forcing either the two metrics to be proportional at the background level or the models to become singly coupled. Proportional backgrounds are particularly interesting as they provide stable cosmological solutions with phenomenologies equivalent to that of $\mathrm{\Lambda }\mathrm{CDM}$ at the background level as well as for linear perturbations, while nonlinearities are expected to show deviations from the standard model.

To explore whether there is new physics going beyond the standard cosmological model or not, we constrain seven cosmological models by combining the latest and largest Pantheon Type Ia supernovae sample with the data combination of baryonic acoustic oscillations, cosmic microwave background radiation, Planck lensing and cosmic chronometers. We find that a spatially flat universe is preferred in the framework of $\mathrm{\Lambda }\mathrm{CDM}$ cosmology, that the constrained equation of state of dark energy is very consistent with the cosmological constant hypothesis in the $\omega \mathrm{CDM}$ model, that there is no evidence of dynamical dark energy in the dark energy density-parametrization model, that there is no hint of interaction between dark matter and dark energy in the dark sector of the universe in the decaying vacuum model, and that there does not exist the sterile neutrino in the neutrino sector of the universe in the $\mathrm{\Lambda }\mathrm{CDM}$ model. We also give the 95% upper limit of the total mass of three active neutrinos $\mathrm{\Sigma }{m}_{\nu }<0.178\mathrm{eV}$ under the assumption of $\mathrm{\Lambda }\mathrm{CDM}$ scenario. It is clear that there is no any departure from the standard cosmological model based on current observational datasets.

We use a recent scaling analysis of the quasielastic electron scattering data from ${}^{12}\mathrm{C}$ to predict the quasielastic charge-changing neutrino scattering cross sections within an uncertainty band. We use a scaling function extracted from a selection of the $(e,e^{\prime })$ cross section data, and an effective nucleon mass inspired by the relativistic mean-field model of nuclear matter. The corresponding superscaling analysis with relativistic effective mass (SuSAM*) describes a large amount of the electron data lying inside a phenomenological quasielastic band. The effective mass incorporates the enhancement of the transverse current produced by the relativistic mean field. The scaling function incorporates nuclear effects beyond the impulse approximation, in particular meson-exchange currents and short-range correlations producing tails in the scaling function. Besides its simplicity, this model describes the neutrino data as reasonably well as other more sophisticated nuclear models.

The scenario of two mass-degenerate Higgs bosons within the general two-Higgs-doublet model (2HDM) is revisited. We focus on the global picture when two $CP$-even Higgs bosons of $h$ and $H$ are nearly mass-degenerate. A global fit to the signal strength of the 125 GeV Higgs measured at the LHC is performed. Based on the best-fit result of the 2HDM mixing angles $(\alpha ,\beta )$, theoretical constraints, charged and $CP$-odd Higgs boson direct search constraints and the electroweak precision constraints are imposed to the 2HDM parameter space. We present the signal predictions of the $(4b,2b2\gamma )$ channels for the benchmark models at the LHC 14 TeV runs. We also study the direct Higgs boson pair productions at the LHC, and the Z-associated Higgs boson pair production search at the ILC 500 GeV runs, as well as the indirect probes at the CEPC 250 GeV run. We find that the mass-degenerate Higgs boson scenario in the Type-II 2HDM can be fully probed by these future experimental searches.