In the present work, we consider the influence on the heavy quark correlators due to the instanton background in the framework of instanton liquid model (ILM) of QCD vacuum by taking into account also the perturbative gluon effects. For a single heavy quark, this leads to the mass shift due to the direct-instanton nonperturbative and ILM modified perturbative contributions, respectively. In the heavy quark-antiquark ($Q\overline{Q}$) sector, we obtain the potential consisting the direct instanton induced part and the one-gluon exchange (OGE) perturbative part, which is screened at large distances due to the nonperturbative dynamics. At the region of interest corresponding to the heavy quark physics, the screening effect in OGE can be well approximated by a Yukawa-type potential in terms of the dynamically generated gluon mass. A possible implication of the present studies to the phenomenology of heavy quarkonium is also discussed.

The Coleman-Weinberg (CW) renormalization scheme for renormalization-group improvement of the effective potential is particularly valuable for CW symmetry-breaking mechanisms (including the challenging case of models with multiple scalar fields). CW mechanism is typically studied using models with classical scale invariance which not only provide a possibility for an alternative symmetry breaking mechanism but also partially address the gauge hierarchies through dimensional transmutation. As outlined in our discussion section, when the couplings are not large, models with CW symmetry-breaking mechanisms have also been shown to naturally provide the strong first-order phase transition necessary for stochastic gravitational wave signals. A full understanding of the CW-MS scheme transformation of couplings thus becomes important in the era of gravitational wave detection and precision coupling measurements. A generalized Coleman-Weinberg (GCW) renormalization scheme is formulated and methods for transforming scalar self-couplings between the GCW and MS (minimal-subtraction) renormalization schemes are developed. Scalar $\lambda {\mathrm{\Phi }}^4$ theory with global $O(4)$ symmetry is explicitly studied up to six-loop order to explore the magnitude of this scheme transformation effect on the couplings. The dynamical rescaling of renormalization scales between the GCW and MS schemes can lead to significant (order of 10%) differences in the coupling at any order, and consequently GCW-MS scheme transformation effects must be considered within precision determinations of scalar couplings in extensions of the Standard Model.

In this paper, we discuss the single diffractive production of open heavy flavor mesons and nonprompt charmonia in $pp$ collisions. Using the color dipole approach, we found that the single diffractive production constitutes 0.5%–2% of the inclusive production of the same mesons. In Tevatron kinematics, our theoretical results are in reasonable agreement with the available experimental data. In LHC kinematics, we found that the cross section is sufficiently large and could be accessed experimentally. We also analyzed the dependence on multiplicity of coproduced hadrons and found that it is significantly slower than that of inclusive production of the same heavy mesons.

In this work, we study the Higgs boson decays into two photons and into one photon and one $Z$ gauge boson within the context of the nonlinear effective field theory called the electroweak chiral Lagrangian (EChL). We present a detailed computation of the corresponding amplitudes to one-loop level in the covariant $R_{\xi }$ gauges. We assume that the fermionic loop contributions are as in the Standard Model and focus here just in the computation of the bosonic loop contributions. Our renormalization program and the anatomy of the various contributions participating in the $R_{\xi }$ gauges are fully explored. With this present computation, we demonstrate the gauge invariance of the EChL result, not only for the case of on-shell Higgs boson, but also for the most general and interesting case of off-shell Higgs boson. We finally analyze and conclude on the special relevance of the Goldstone boson loops, in good agreement with the expected chiral loops behavior in chiral Lagrangians. We perform a systematic comparison with the corresponding computation of the Standard Model in the $R_{\xi }$ gauges and with the previous EChL results in the unitary gauge. This work represents the first computation within the EChL of these observables to one loop, for both on- and off-shell Higgs boson, in the most general $R_{\xi }$ gauges and with a full renormalization program description, not yet fully explored in the previous literature and which is different to the most frequently used in the linear effective field theory.

We study dark matter (DM) in the exceptional supersymmetric standard model. The model has both active and inert Higgs superfields, and by imposing discrete symmetries one can generate two DM candidates. We show that the lightest Higgsinos of the active and inert sectors give a viable setup for two-component DM. We also illustrate the scope of both direct and indirect detection experiments in extracting such a DM sector. Future experiments of the former kind have a good chance of finding the active component while the inert Higgsino will be very hard to detect, while those of the latter kind will have no sensitivity to either candidate.

The model of heavy neutral leptons (HNLs) is one of the well-motivated models beyond the standard model from both theoretical and phenomenological point of views. It is an indispensable ingredient to explain the puzzle of tiny neutrino masses and the origin of the matter-antimatter asymmetry in our Universe, based on the models in which the simplest type-I seesaw mechanism can be embedded. The HNL with a mass up to the electroweak scale is an attractive scenario which can be readily tested in present or near-future experiments including the LHC. In this work, we study the decay rates of HNLs and find the sensitive parameter space of the mixing angles between the active neutrinos and HNLs. Since there are fewer collider studies of the mixing between ${\nu }_{\tau }$ and HNL in literature compared with those of ${\nu }_e$ and ${\nu }_{\mu }$ for the HNL of mass in the electroweak scale, we focus on the channel $pp\to W^{\pm (*)}+X\to {\tau }^{\pm }N+X$ to search for HNLs at the LHC 14 TeV. The targeted signature consists of three prompt charged leptons, which include at least two tau leptons. After the signal-background analysis, we further set sensitivity bounds on the mixing $|U_{\tau N}{|}^2$ with $M_N$ at high-luminosity LHC (HL-LHC). We predict the testable bounds from HL-LHC can be stronger than the previous LEP constraints and electroweak precision data (EWPD), especially for $M_N\lesssim 50\mathrm{GeV}$ can reach down to $|U_{\tau N}{|}^2\approx 5\times {10}^{-6}$.

We identify the two scalar leptoquarks capable of generating sign-dependent contributions to leptonic magnetic moments, $R_2\sim (\mathbf{3},\mathbf{2},7/6)$ and $S_1\sim (\mathbf{3},\mathbf{1},-1/3)$, as favored by current measurements. We consider the case in which the electron and muon sectors are decoupled, and real-valued Yukawa couplings are specified using an up-type quark mass-diagonal basis. Contributions to $\mathrm{\Delta }{a}_e$ arise from charm-containing loops and $\mathrm{\Delta }{a}_{\mu }$ from top-containing loops—hence avoiding dangerous LFV constraints, particularly from $\mu \to e\gamma$. The strongest constraints on these models arise from contributions to the $Z$ leptonic decay widths, high-$p_T$ leptonic tails at the LHC, and from (semi)leptonic kaon decays. To be a comprehensive solution to the $(g-2{)}_{e/\mu }$ puzzle we find that the mass of either leptoquark must be $\lesssim 65\mathrm{TeV}$. This analysis can be embedded within broader flavor anomaly studies, including those of hierarchical leptoquark coupling structures. It can also be straightforwardly adapted to accommodate future measurements of leptonic magnetic moments, such as those expected from the Muon $g-2$ collaboration in the near future.

Precise knowledge of the nucleon’s axial-current form factors is crucial for modeling GeV-scale neutrino-nucleus interactions. Unfortunately, the axial form factor remains insufficiently constrained to meet the precision requirements of upcoming long-baseline neutrino-oscillation experiments. This work studies the nucleon’s axial and vector form factors using the light-front approach to build a quark-diquark model of the nucleon with an explicit pion cloud. The light-front wave functions in both the quark and pion-baryon Fock spaces are first calibrated to existing experimental information on the nucleon’s electromagnetic form factors and then used to predict the axial form factor. The resulting squared charge radius of the axial pseudovector form factor is predicted to be $r_A^2=0.29\pm 0.03{\mathrm{fm}}^2$, where the small error accounts for the model’s parametric uncertainty. We use our form factor results to explore the (quasi)elastic scattering of neutrinos by (nuclei)nucleons, with the result that the widely implemented dipole ansatz is an inadequate approximation of the full form factor for modeling both processes. The approximation leads to a 5%–10% overestimation of the total cross section, depending on the (anti)neutrino energy. We project overestimations of similar size in the flux-averaged cross sections for the upcoming DUNE long-baseline neutrino-oscillation experiment.

After the recent discovery of the new ${\mathrm{\Omega }}^{*}$ state, the ratio of the branching fractions of $\mathrm{\Omega }(2012)\to \overline{K}\pi \mathrm{\Xi }$ relative to the $\overline{K}\mathrm{\Xi }$ decay channel was investigated by the Belle Collaboration. The measured 11.9% upper limit to this ratio is in sharp tension with the $S$-wave $\overline{K}\mathrm{\Xi }(1530)$ molecule interpretation for $\mathrm{\Omega }(2012)$, which indicates the dominant $\overline{K}\pi \mathrm{\Xi }$ three-body decay. We try to explore the possibility of the $P$-wave molecule assignments for $\mathrm{\Omega }(2012)$ [where $\mathrm{\Omega }(2012)$ has positive parity]. It is found that the latest experimental measurements are compatible with the $1/2^{+}$ and $3/2^{+}$ $\overline{K}\mathrm{\Xi }(1530)$ molecular pictures, while the $5/2^{+}$ $\overline{K}\mathrm{\Xi }(1530)$ molecule shows larger $\overline{K}\pi \mathrm{\Xi }$ three-body decay than $\overline{K}\mathrm{\Xi }$ decay as in the case of an $S$-wave molecule. Thus, the newly observed $\mathrm{\Omega }(2012)$ can be interpreted as the $1/2^{+}$ or $3/2^{+}$ $\overline{K}\mathrm{\Xi }(1530)$ molecule state according to current experiment data.

The PHENIX experiment has measured the spin alignment for inclusive $J/\psi \to e^{+}{e}^{-}$ decays in proton-proton collisions at $\sqrt{s}=510\mathrm{GeV}$ at midrapidity. The angular distributions have been measured in three different polarization frames, and the three decay angular coefficients have been extracted in a full two-dimensional analysis. Previously, PHENIX saw large longitudinal net polarization at forward rapidity at the same collision energy. This analysis at midrapidity, complementary to the previous PHENIX results, sees no sizable polarization in the measured transverse momentum range of $0.0<p_T<10.0\mathrm{GeV}/c$. The results are consistent with a previous one-dimensional analysis at midrapidity at $\sqrt{s}=200\mathrm{GeV}$. The transverse-momentum-dependent cross section for midrapidity $J/\psi$ production has additionally been measured, and after comparison to world data, a simple logarithmic dependence of the cross section on $\sqrt{s}$ was found.

In understanding the quantum physics of a black hole, nonperturbative aspects of gravity play important roles. In particular, huge gauge redundancies of a gravitational theory at the nonperturbative level, which are much larger than the standard diffeomorphism and relate even spaces with different topologies, allow us to take different descriptions of a system. While the physical conclusions are the same in any description, the same physics may manifest itself in vastly different forms in descriptions based on different gauge choices. In this paper, we explore the relation between two such descriptions, which we refer to as the global gauge and unitary gauge constructions. The former is based on the global spacetime of general relativity, in which understanding unitarity requires the inclusion of subtle nonperturbative effects of gravity. The latter is based on a distant view of the black hole, in which unitarity is manifest but the existence of interior spacetime is obscured. These two descriptions are complementary. In this paper, we initiate the study of learning aspects of one construction through the analysis of the other. We find that the existence of near empty interior spacetime manifest in the global gauge construction is related to the maximally chaotic, fast scrambling, and universal dynamics of the horizon in the unitary gauge construction. We use the complementarity of the gauge choices to understand the ensemble nature of the gravitational path integral in global spacetime in terms of coarse graining and thermality in a single unitary theory that does not involve any ensemble nature at the fundamental level. We also discuss how the interior degrees of freedom are related with those in the exterior in the two constructions. This relation emerges most naturally as entanglement wedge reconstruction and the effective theory of the interior in the respective constructions.

Theories of gravity that incorporate new scalar degrees of freedom typically require “screening mechanisms” to ensure consistency with Solar System tests. One widely studied mechanism—the chameleon mechanism—can lead to violations of the equivalence principle (EP), as screened and unscreened objects fall differently. If the stars are screened but the surrounding dark matter is not, EP violation can lead to asymmetry between leading and trailing streams from tidally disrupted dwarf galaxies in the Milky Way halo. We provide analytic estimates of the magnitude of this effect for realistic Galactic mass distributions, demonstrating that it is an even more sensitive probe than suggested previously. Using a restricted $N$-body code, we simulate four satellites with a range of masses and orbits, together with a variety of strengths of the fifth force and screening levels of the Milky Way and satellite. The ratio of the cumulative number function of stars in the leading and trailing stream as a function of longitude from the satellite is computable from simulations and measurable from the stellar data and can provide a direct test of chameleon gravity. We forecast constraints for streams at large Galactocentric distances, which probe deeper into chameleon parameter space, using the specific example case of Hu-Sawicki $f(R)$ gravity. Streams in the outer reaches of the Milky Way halo (with apocenters between 100 and 200 kpc) provide easily attainable constraints at the level of $|f_{R0}|={10}^{-7}$. Still more stringent constraints at the level of ${10}^{-7.5}$ or even ${10}^{-8}$ are plausible provided the environmental screening of the satellite is accounted for, and screening of the Milky Way’s outer halo by the Local Group is not yet triggered in this range. These would be among the tightest astrophysical constraints to date. We note three further signatures of chameleon gravity: (i) the trailing stellar stream may become detached from the dark matter progenitor if all the stars are lost, (ii) in the extreme fifth force regime, striations in the stellar trailing tail may develop from material liberated at successive pericentric passages, and (iii) if the satellite is fully screened, its orbital frequency is lower than that of the associated dark matter, which is preferentially liberated into the leading tidal tail.

We introduce a procedure to determine the size and shape of normal neighborhoods in any spacetimes and their dependence on the precision of the measurements performed by arbitrary observers. As an example, we consider the Schwarzschild geometry in Riemann and Fermi normal coordinates and determine the size and shape of normal neighborhoods in the vicinity of the event horizon. Depending on the observers, normal neighborhoods extend to the event horizon and even beyond into the black hole interior. It is shown that the causal structure supported by normal neighborhoods across an event horizon is consistent with general relativity. In particular, normal neighborhoods reaching over an event horizon are void of the Schwarzschild coordinate singularity. In addition, we introduce a new variant of normal coordinates which we call Fermi normal coordinates around a point, unifying features of Riemann and Fermi normal coordinates, and analyze their neighborhoods.

Recently, Takamoto et al. (2020) have discussed high precision measurements of gravity induced time dilation effects on optical lattice clocks located near the Earth surface. A relative tick frequency change, $\delta \nu /{\nu }_0=(49337.8\pm 4.3){10}^{-18}$, is found between two optical lattice clocks, one located at the ground floor, $h=0\mathrm{m}$, and the second one at an altitude $h_{\exp }=452.596\mathrm{m}$, on the Skytree tower in Tokyo. The results are compared with the predictions of Einstein’s equivalence principle (EEP) estimated as an average over gravimeter measurements at $h=0\mathrm{m}$ and $h=450\mathrm{m}$. We present a different derivation of the EEP prediction based on the calculation of the effective gravitational potential on the ground floor and at $h=h_{\exp }$, in excellent agreement with the value $\delta \nu /{\nu }_0$, providing an independent method to validate the differences in time dilation measured experimentally. In addition, we obtain the next-order correction to the present results, which may be tested in future more accurate experiments.

Gravitationally bound structures composed by fermions and scalar particles known as fermion-boson stars are regular and static configurations obtained by solving the coupled Einstein-Klein-Gordon-Euler system. In this work, we discuss one possible scenario through which these fermion-boson stars may form by solving numerically the Einstein-Klein-Gordon-Euler system under the simplifying assumption of spherical symmetry. Our initial configurations assume an already existing neutron star surrounded by an accreting cloud of a massive and complex scalar field. The results of our simulations show that once part of the initial scalar field is expelled via gravitational cooling the system gradually oscillates around an equilibrium configuration that is asymptotically consistent with a static solution of the system. The formation of fermion-boson stars for large positive values of the coupling constant in the self-interaction term of the scalar-field potential reveal the presence of a node in the scalar field. This suggests that a fermionic core may help stabilize configurations with nodes in the bosonic sector, as happens for purely boson stars in which the ground state and the first excited state coexist.

We anticipate noise from the Laser Interferometer Space Antenna (LISA) will exhibit nonstationarities throughout the duration of its mission due to factors such as antenna repointing, cyclostationarities from spacecraft motion, and glitches as highlighted by LISA Pathfinder. In this paper, we use a surrogate data approach to test the stationarity of a time series which does not rely on the Gaussianity assumption. The main goal is to identify noise nonstationarities in the future LISA mission. This will be necessary for determining how often the LISA noise power spectral density (PSD) will need to be updated for parameter estimation routines. We conduct a thorough simulation study illustrating the power/size of various versions of the hypothesis tests and then apply these approaches to differential acceleration measurements from LISA Pathfinder. We also develop a data analysis strategy for addressing nonstationarities in the LISA PSD, where we update the noise PSD over time, while simultaneously conducting parameter estimation, with a focus on planned data gaps.

We obtain the solution of a generalized Ayón-Beato–García (ABG) black hole with the nonlinear tensor field $B_{\mu \nu }$ in scalar-tensor-vector gravity (STVG), called the generalized ABG STVG black hole. This black hole is endowed with four parameters, the black hole mass $M$, the parameter $\alpha$ associated with STVG theory, and the two parameters $\lambda$ and $\beta$ that are related to the dipole and quadrupole moments of the nonlinear tensor field, respectively. By analyzing the characteristics of the black hole, we find that the generalized ABG STVG black hole is regular when $\lambda \ge 3$ and $\beta \ge 4$, and we study the effects of the parameters $\alpha$, $\lambda$, and $\beta$ on the black hole horizon. We calculate the quasinormal mode frequencies of the odd parity gravitational perturbation for the generalized ABG STVG black hole by using the sixth order WKB approximation method and simultaneously using the null geodesic method at the eikonal limit. The results show that the increase of the parameters $\alpha$ and $\lambda$ makes the gravitational waves decay slowly, while the increase of the parameter $\beta$ makes the gravitational waves decay fast at first, then slowly. In addition, we verify that the improved correspondence between the real part of quasinormal frequencies at the eikonal limit and the shadow radius is valid for the generalized ABG STVG black hole.

It has recently been proved numerically that spinning black holes in Einstein-scalar theories which are characterized by a nonminimal negative coupling of the scalar field to the Gauss-Bonnet invariant of the curved spacetime may develop exponentially growing instabilities. Intriguingly, it has been demonstrated that this tachyonic instability, which marks the onset of the spontaneous scalarization phenomenon in the Einstein-Gauss-Bonnet-scalar theory, characterizes spinning black holes whose dimensionless angular momentum parameter $\overline{a}\equiv a/M$ is larger than some critical value ${\overline{a}}_{\mathrm{crit}}\simeq 0.505$. In the present paper we prove, using analytical techniques, that the critical rotation parameter which marks the boundary between bald Kerr black holes and hairy (scalarized) spinning black holes in the Einstein-Gauss-Bonnet-scalar theory is given by the exact dimensionless relation ${\overline{a}}_{\mathrm{crit}}=\frac{1}{2}$.

The recent observations of the global 21-cm signal by EDGES and gravitational waves by LIGO/VIRGO have revived interest in primordial black holes (PBHs). Motivated by these observations, many previous works focused on PBHs with lifetimes larger than the present age of the Universe. The influence of massive PBHs with $M_{\mathrm{PBH}}\sim \mathcal{O}({10}^2)M_{\odot }$ (taking into account radiation from gas accretion onto PBHs) and less massive PBHs with $M_{\mathrm{PBH}}\gtrsim {10}^{15}\mathrm{g}$ (taking into account Hawking radiation) on the intergalactic medium (IGM) have been considered. Different from previous works, we investigate the influence of PBHs on the evolution of the IGM for the mass range $6\times {10}^{13}\mathrm{g}\lesssim M_{\mathrm{PBH}}\lesssim 3\times {10}^{14}\mathrm{g}$. Since the lifetime of these PBHs is smaller than the present age of the Universe, they have evaporated by the present day. Due to Hawking radiation, the heating effects of PBHs on the IGM can suppress the absorption amplitude of the global 21-cm signal. In this work, by requiring that the differential brightness temperature of the global 21-cm signal be in the redshift range of $10\lesssim z\lesssim 30$, i.e., $\delta T_b\lesssim -100\mathrm{mK}$, we obtain upper limits on the initial mass fraction of PBHs. We find that the strongest upper limit is ${\beta }_{\mathrm{PBH}}\sim 2\times {10}^{-30}$. Since the formation of PBHs is related to primordial curvature perturbations, by using the constraints on the initial mass fraction of PBHs we obtain upper limits on the power spectrum of primordial curvature perturbations for the scale range $8.0\times {10}^{15}\lesssim k\lesssim 1.8\times {10}^{16}{\mathrm{Mpc}}^{-1}$, corresponding to the mass range considered here. We find that the strongest upper limit is ${\mathcal{P}}_{\mathcal{R}}(k)\sim 0.0046$. By comparing with previous works, we find that for the mass range (or the scale range) investigated in this work the global 21-cm signal or the 21-cm power spectrum should give the strongest upper limits on the initial mass fraction of PBHs and on the power spectrum of primordial curvature perturbations.

Cosmic voids, the underdense regions in the universe, are particularly sensitive to diffuse density components such as cosmic neutrinos. This sensitivity is enhanced by the match between void sizes and the free-streaming scale of massive neutrinos. Using the massive neutrino simulations massivenus, we investigate the effect of neutrino mass on dark matter halos as a function of environment. We find that the halo mass function depends strongly on neutrino mass and that this dependence is more pronounced in voids than in high-density environments. An observational program that measured the characteristic mass of the most massive halos in voids should be able to place novel constraints on the sum of the masses of neutrinos $\sum m_{\nu }$. The neutrino mass effect in the simulations is quite strong: In a ${512}^3{h}^{-3}{\mathrm{Mpc}}^3$ survey, the mean mass of the 1000 most massive halos in the void interiors is $(4.82\pm 0.11)\times {10}^{12}{h}^{-1}{M}_{\odot }$ for $\sum m_{\nu }=0.6\mathrm{eV}$ and $(8.21\pm 0.13)\times {10}^{12}{h}^{-1}{M}_{\odot }$ for $\sum m_{\nu }=0.1\mathrm{eV}$. Subaru (SuMIRe), Euclid and WFIRST will have both spectroscopic and weak lensing surveys. Covering volumes at least 50 times larger than our simulations, they should be sensitive probes of neutrino mass through void substructure.