Herein we use the measurements of the AMS-02 electron flux for the first time in order to derive limits on the dark-matter annihilation cross section and lifetime for the specific final states of ${\mu }^{+}{\mu }^{-}$ and ${\tau }^{+}{\tau }^{-}$. With the well-motivated assumption that the electrons were generated from astrophysical processes, we impose strong limits on the dark-matter properties that are insensitive of propagation parameters and nucleon injection parameters when the dark matter particle mass ($m_{\chi }$) is larger than $\sim 200\mathrm{GeV}$. Specifically, our limits are stronger than those derived from the positron fraction or flux for $m_{\chi }>100\mathrm{GeV}$, and the dark-matter annihilation (or decay) origin of the AMS-02 positron anomaly is found to be disfavored.

In this paper, we search for the regions of the phenomenological minimal supersymmetric standard model (pMSSM) parameter space where one can expect to have moderate Higgs mixing angle ($\alpha$) with relatively light (up to 600 GeV) additional Higgses after satisfying the current LHC data. We perform a global fit analysis using most updated data (till December 2014) from the LHC and Tevatron experiments. The constraints coming from the precision measurements of the rare b-decays $B_s\to {\mu }^{+}{\mu }^{-}$ and $b\to s\gamma$ are also considered. We find that low $M_A(\lesssim 350)$ and high $\tan \beta (\gtrsim 25)$ regions are disfavored by the combined effect of the global analysis and flavor data. However, regions with Higgs mixing angle $\alpha \sim 0.1–0.8$ are still allowed by the current data. We then study the existing direct search bounds on the heavy scalar/pseudoscalar ($\mathrm{H}/\mathrm{A}$) and charged Higgs boson (${\mathrm{H}}^{\pm }$) masses and branchings at the LHC. It has been found that regions with low to moderate values of $\tan \beta$ with light additional Higgses (mass $\le 600\mathrm{GeV}$) are unconstrained by the data, while the regions with $\tan \beta >20$ are excluded considering the direct search bounds by the LHC-8 data. The possibility to probe the region with $\tan \beta \le 20$ at the high luminosity run of LHC are also discussed, giving special attention to the $\mathrm{H}\to \mathrm{hh}$, $\mathrm{H}/\mathrm{A}\to \mathrm{t}\overline{\mathrm{t}}$ and $\mathrm{H}/\mathrm{A}\to {\tau }^{+}{\tau }^{-}$ decay modes.

Verifying $V_{tb}\simeq 1$ is critical to test the three generation assumption of the Standard Model. So far our best knowledge of $V_{tb}$ is inferred either from the $3\times 3$ unitarity of the Cabibbo-Kobayashi-Maskawa matrix or from single top-quark productions upon the assumption of universal weak couplings. The unitarity could be relaxed in new physics models with extra heavy quarks and the universality of weak couplings could also be broken if the $Wtb$ coupling is modified in new physics models. In this paper we propose to measure $V_{tb}$ in the process of $e^{+}{e}^{-}\to t\overline{t}$ without prior knowledge of the number of fermion generations or the strength of the $Wtb$ coupling. Using an effective Lagrangian approach, we perform a model-independent analysis of the interactions among electroweak gauge bosons and the third generation quarks, i.e. the $Wtb$, $Zt\overline{t}$ and $Zb\overline{b}$ couplings. The electroweak symmetry of the Standard Model specifies a pattern of deviations of the $Z\text{−}{t}_L\text{−}{t}_L$ and $W\text{−}{t}_L\text{−}{b}_L$ couplings after one imposes the known experimental constraint on the $Z\text{−}{b}_L\text{−}{b}_L$ coupling. We demonstrate that, making use of the predicted pattern and the accurate measurements of top-quark mass and width from the energy threshold scan experiments, one can determine $V_{tb}$ from the cross section and the forward-backward asymmetry of top-quark pair production at an unpolarized electron-positron collider.

The Casimir force for a planar gauge model is studied considering perfect conducting and perfect magnetically permeable boundaries. By using an effective model describing planar vortex excitations, we determine the effect these can have on the Casimir force between parallel lines. Two different mappings between models are considered for the system under study, where generic boundary conditions can be more easily applied and the Casimir force can be derived in a more straightforward way. It is shown that vortex excitations can be an efficient suppressor of vacuum fluctuations. In particular, for the model studied here, a planar Chern-Simons type of model that allows for the presence of vortex matter, the Casimir force is found to be independent of the choice of boundary conditions, at least for the more common types, like Neumann, perfect conducting and magnetically permeable boundary conditions. We give an interpretation for these results and some possible applications for them are also discussed.

We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around $2M_{\odot }$ for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows one to reach two solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.

Within the framework of the Duffin-Kemmer-Petiau (DKP) formalism a more consistent approach to the derivation of the third order wave equation obtained earlier by M. Nowakowski [1] on the basis of heuristic considerations is suggested. For this purpose an additional algebraic object, the so-called $q$-commutator ($q$ is a primitive cubic root of unity) and a new set of matrices ${\eta }_{\mu }$ instead of the original matrices ${\beta }_{\mu }$ of the DKP algebra are introduced. It is shown that in terms of these ${\eta }_{\mu }$ matrices we have succeeded in reducing a procedure of the construction of cubic root of the third order wave operator to a few simple algebraic transformations and to a certain operation of the passage to the limit $z\to q$, where $z$ is some complex deformation parameter entering into the definition of the $\eta$-matrices. A corresponding generalization of the result obtained to the case of the interaction with an external electromagnetic field introduced through the minimal coupling scheme is carried out and a comparison with M. Nowakowski’s result is performed. A detailed analysis of the general structure for a solution of the first order differential equation for the wave function $\psi (x;z)$ is performed and it is shown that the solution is singular in the $z\to q$ limit. The application to the problem of construction within the DKP approach of the path integral representation in parasuperspace for the propagator of a massive vector particle in a background gauge field is discussed.

When spatial boundaries are inserted, supersymmetry (SUSY) can be broken. We have shown that in an $\mathcal{N}=2$ supersymmetric theory, all local boundary conditions allowed by self-adjointness of the Hamiltonian break $\mathcal{N}=2$ SUSY, while only a few of these boundary conditions preserve $\mathcal{N}=1$ SUSY. We have also shown that for a subset of the boundary conditions compatible with $\mathcal{N}=1$ SUSY, there exist fermionic ground states which are localized near the boundary. We also show that only very few nonlocal boundary conditions like periodic boundary conditions preserve full $\mathcal{N}=2$ supersymmetry, but none of them exhibits edge states.

We analytically calculate the influence of a plasma on the shadow of a black hole (or of another compact object). We restrict to spherically symmetric and static situations, where the shadow is circular. The plasma is assumed to be nonmagnetized and pressureless. We derive the general formulas for a spherically symmetric plasma density on an unspecified spherically symmetric and static spacetime. Our main result is an analytical formula for the angular size of the shadow. As a plasma is a dispersive medium, the radius of the shadow depends on the photon frequency. The effect of the plasma is significant only in the radio regime. The formalism applies not only to black holes but also, e.g., to wormholes. As examples for the underlying spacetime model, we consider the Schwarzschild spacetime and the Ellis wormhole. In particular, we treat the case that the plasma is in radial free fall from infinity onto a Schwarzschild black hole. We find that for an observer far away from a Schwarzschild black hole, the plasma has a decreasing effect on the size of the shadow. The perspectives of actually observing the influence of a plasma on the shadows of supermassive black holes are discussed.

The Schwarzschild exterior space-time is conformally related to a direct product space-time, ${\mathcal{M}}_2\times {\mathbb{S}}_2$, where ${\mathcal{M}}_2$ is a $2D$ space-time. This direct product structure arises naturally when considering the wave equation on the Schwarzschild background. Motivated by this, we establish some geometrical results relating to ${\mathcal{M}}_2$ that are useful for black hole physics. We prove that ${\mathcal{M}}_2$ has the rare property of being a causal domain. Consequently, Synge’s world function and the Hadamard form for the Green function on this space-time are well defined globally. We calculate the world function and the van Vleck determinant on ${\mathcal{M}}_2$ numerically and point out how these results will be used to establish global properties of Green functions on the Schwarzschild black hole space-time.

In this paper we apply the usual perturbative methodology to evaluate the one-loop effective potential in a nonlocal scalar field theory. We find that the effect induced by the nonlocality of the theory is always very small and we discuss the consequences of this result. In particular we argue that, looking at one-loop corrections for matter fields, it is not possible to find signals of the nonlocality of the theory in cosmological observables since, even during inflation when energies are very high, nonlocality-induced corrections are expected to be very small.

Under standard assumptions including stationary and serially uncorrelated Gaussian gravitational wave stochastic background signal and noise distributions, as well as homogenous detector sensitivities, the standard cross-correlation detection statistic is known to be optimal in the sense of minimizing the probability of a false dismissal at a fixed value of the probability of a false alarm. The focus of this paper is to analyze the comparative efficiency of this statistic, vs a simple alternative statistic obtained by cross-correlating the squared measurements, in situations that deviate from such standard assumptions. We find that differences in detector sensitivities have a large impact on the comparative efficiency of the cross-correlation detection statistic, which is dominated by the alternative statistic when these differences reach 1 order of magnitude. This effect holds even when both the signal and noise distributions are Gaussian. While the presence of non-Gaussian signals has no material impact for reasonable parameter values, the relative inefficiency of the cross-correlation statistic is less prominent for fat-tailed noise distributions, but it is magnified in case noise distributions have skewness parameters of opposite signs. Our results suggest that introducing an alternative detection statistic can lead to noticeable sensitivity gains when noise distributions are possibly non-Gaussian and/or when detector sensitivities exhibit substantial differences, a situation that is expected to hold in joint detections from Advanced LIGO and Advanced Virgo, in particular in the early phases of development of the detectors, or in joint detections from Advanced LIGO and the Einstein Telescope.

In this work, we explore the flavor-changing decays $H_i\to bs$ in a general supersymmetric scenario. In these models the flavor-changing decays arise at loop level, but—because they originate from a dimension-four operator—they do not decouple and may provide a first sign of new physics for heavy masses beyond the reach of colliders. In the framework of the minimal supersymmetric extension of the Standard Model, we find that the largest branching ratio of the lightest Higgs ($H_1$) is $\mathcal{O}(10^{-6})$ after imposing present experimental constraints, while heavy Higgs states may still present branching ratios $\mathcal{O}(10^{-3})$. In a more general supersymmetric scenario, where additional Higgs states may modify the Higgs mixings, the branching ratio $\mathrm{BR}(H_1\to bs)$ can reach values $\mathcal{O}(10^{-4})$, while heavy Higgses still remain at $\mathcal{O}(10^{-3})$. Although these values are clearly out of reach for the LHC, a full study in a linear collider environment could be worth pursuing.

We revisit the neutrino magnetic moments (MMs) in the left-right model with nonmanifest symmetry. After deriving an expression in terms of the Dirac and Majorana phases, we analyze the sensitivity of neutrino MMs to these $CP$-violating phases in two scenarios: (1) a maximal right mixing in which left- and right-handed neutrinos are mixed by the same matrix, and (2) a right-handed neutrino mixing whose off diagonal entries are much smaller than the elements in the diagonal, but where the $CP$ phases remain general. Our results show that, even though certain values of the Majorana phases can eliminate neutrino MMs, the presence of a maximal $CP$-violating phase in neutrino mixing matrix, as favored by the discrepancy between T2K results and reactor measurements in neutrino oscillations, requires that at least one neutrino have a large nonzero MM.

We consider the most general set of $SU(2)\times U(1)$ invariant $CP$-violating operators of dimension six, which contribute to $VVh$ interactions ($V=W$, $Z$, $\gamma$). Our aim is to constrain any $CP$-violating new physics above the electroweak scale via the effective couplings that arise when such physics is integrated out. For this purpose, we use, in turn, electroweak precision data, global fits of Higgs data at the Large Hadron Collider and the electric dipole moments of the neutron and the electron. We thus impose constraints mainly on two-parameter and three-parameter spaces. We find that the constraints from the electroweak precision data are the weakest. Among the existing Higgs search channels, considerable constraints come from the diphoton signal strength. We note that potential contribution to $h\to \gamma Z$ may in principle be a useful constraining factor, but it can be utilized only in the high energy run. The contributions to electric dipole moments mostly lead to the strongest constraints, though somewhat fine-tuned combinations of more than one parameter with large magnitudes are allowed. We also discuss constraints on gauge boson trilinear couplings which depend on the parameters of the $CP$-violating operators.

We demonstrate that current and planned underground neutrino experiments could offer a powerful probe of few-MeV dark matter when combined with a nearby high-intensity low-to-medium energy electron accelerator. This experimental setup, an underground beam-dump experiment, is capable of decisively testing the thermal freeze-out mechanism for several natural dark matter scenarios in this mass range. We present the sensitivity reach in terms of the mass-coupling parameter space of existing and planned detectors, such as Super-K and $\mathrm{SNO}+$, in conjunction with a hypothetical 100-MeV energy accelerator. This setup can also greatly extend the sensitivity of direct searches for new light weakly coupled force carriers independent of their connection to dark matter.

We examine the impact of the expected reach of the LHC and the XENON1T experiments on the parameter space of the minimal classically scale invariant extension of the standard model (SM), where all the mass scales are induced dynamically by means of the Coleman–Weinberg mechanism. In this framework, the SM content is enlarged by the addition of one complex gauge-singlet scalar with a scale invariant and $CP$-symmetric potential. The massive pseudoscalar component, protected by the $CP$ symmetry, forms a viable dark matter candidate, and three flavors of the right-handed Majorana neutrinos are included to account for the nonzero masses of the SM neutrinos via the seesaw mechanism. The projected constraints on the parameter space arise by applying the ATLAS heavy Higgs discovery prospects, with an integrated luminosity of 300 and $3000{\mathrm{fb}}^{-1}$ at $\sqrt{s}=14\mathrm{TeV}$, to the pseudo-Nambu–Goldstone boson of the (approximate) scale symmetry, as well as by utilizing the expected reach of the XENON1T direct detection experiment for the discovery of the pseudoscalar dark matter candidate. A null-signal discovery by these future experiments implies that vast regions of the model’s parameter space can be thoroughly explored; the combined projections are expected to confine a mixing between the SM and the singlet sector to very small values while probing the viability of the TeV scale pseudoscalar’s thermal relic abundance as the dominant dark matter component in the Universe. Furthermore, the vacuum stability and triviality requirements of the framework up to the Planck scale are studied, and the viable region of the parameter space is identified. The results are summarized in extensive exclusion plots, incorporating additionally the prior theoretical and experimental bounds for comparison.

We present results for the isovector and flavor diagonal tensor charges $g_T^{u-d}$, $g_T^u$, $g_T^d$, and $g_T^s$ needed to probe novel tensor interactions at the TeV scale in neutron and nuclear $\beta$-decays and the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice QCD calculations were done using nine ensembles of gauge configurations generated by the MILC collaboration using the HISQ action with $2+1+1$ dynamical flavors. These ensembles span three lattice spacings $a\approx 0.06$, 0.09 and 0.12 fm and three quark masses corresponding to the pion masses $M_{\pi }\approx 130$, 220 and 310 MeV. Using estimates from these ensembles, we quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, volume and light quark masses for the connected contributions. The final estimates of the connected nucleon (proton) tensor charge for the isovector combination is $g_T^{u-d}=1.020(76)$ in the $\overline{\mathrm{MS}}$ scheme at 2 GeV. The additional disconnected quark loop contributions needed for the flavor-diagonal matrix elements are calculated using a stochastic estimator employing the truncated solver method with the all-mode-averaging technique. We find that the size of the disconnected contribution is smaller than the statistical error in the connected contribution. This allows us to bound the disconnected contribution and include it as an additional uncertainty in the flavor-diagonal charges. After a continuum extrapolation, we find $g_T^u=0.774(66)$, $g_T^d=-0.233(28)$ and $g_T^{u+d}=0.541(67)$. The strangeness tensor charge, that can make a significant contribution to the neutron EDM due to the large ratio $m_s/m_{u,d}$, is $g_T^s=0.008(9)$ in the continuum limit.

We investigate the properties of the pion quasiparticle in the low-temperature phase of two-flavor QCD on the lattice with support from chiral effective theory. We find that the pion quasiparticle mass is significantly reduced compared to its value in the vacuum, in contrast with the static screening mass, which increases with temperature. By a simple argument, near the chiral limit the two masses are expected to determine the quasiparticle dispersion relation. Analyzing two-point functions of the axial charge density at nonvanishing spatial momentum, we find that the predicted dispersion relation and the residue of the pion pole are consistent with the lattice data at low momentum. This test, based on fits to the correlation functions, is confirmed by a second analysis using the Backus-Gilbert method.

In this work, inspired by the observation of charmoniumlike $Z_c^{+}(4200)$, we study the photoproduction of charged charmoniumlike $Z_c^{+}(4200)$ with an effective Lagrangian approach and the Regge trajectories model. The numerical results indicate that the Reggeized treatment can lead to a lower total cross section of the $Z_c^{+}(4200)$ photoproduction and the peak position of the cross section was moved to the higher energy point when the Reggeized treatment was added. Moreover, by using the data from the COMPASS experiment and presented theoretical predictions, an upper limit of the decay width of $Z_c(4200)\to J/\psi \pi$ is estimated. The relevant results not only shed light on the further experiment of searching for the charmoniumlike $Z_c(4200)$ state via meson photoproduction, but also provide valuable information for having a better comprehension of the nature of a charmoniumlike $Z_c(4200)$ state.

We study the impact of the precision determination of oscillation parameters in the JUNO experiment on half-life predictions for neutrinoless double beta decay. We show that the solar neutrino mixing angle can be measured by JUNO with below 1% uncertainty. This implies in particular that the minimal value of the effective mass in the inverted mass ordering will be known essentially without uncertainty. We demonstrate that this reduces the range of half-life predictions in order to test this value by a factor of 2. The remaining uncertainty is caused by nuclear matrix elements. This has important consequences for future double beta decay experiments that aim at ruling out the inverted mass ordering or the Majorana nature of neutrinos.