We study the ultraviolet (UV) behavior of an $\mathrm{O}(N)$ $|\overrightarrow{\varphi }{|}^6$ theory in $d=3$ spacetime dimensions, focusing on the question of the range in $N$ over which the perturbative beta function exhibits robust evidence of a UV zero in the $|\overrightarrow{\varphi }{|}^6$ coupling, $g$. The four-loop $(4\ell )$ beta function is known to have a (scheme-independent) UV zero at $g=g_{\mathrm{UV},4\ell }$, which is reliably calculable for large $N$. For our analysis we use the six-loop beta function calculated in the minimal subtraction scheme. We find that this six-loop beta function has a UV zero, $g_{\mathrm{UV},6\ell }$, if $N>N_c$, where $N_c\simeq 796$, and we calculate $g_{\mathrm{UV},6\ell }$. To investigate the reliability of the result in the region of $N\gtrsim N_c$, we apply three methods: (i) calculation of the fractional difference between $g_{\mathrm{UV},4\ell }$ and $g_{\mathrm{UV},6\ell }$, (ii) a Padé approximant, and (iii) an assessment of scheme dependence. Our results provide quantitative measures of the range of $N$ over which the six-loop beta function has a UV zero and of the $1/N$ corrections to the value of $g$ at the UV zero for large but finite $N$. If one imposes a benchmark requirement that the fractional difference between $g_{\mathrm{UV},4\ell }$ and $g_{\mathrm{UV},6\ell }$ must be less than 15%, then our results show that this requirement is satisfied for $N\gtrsim 2\times {10}^3$. The possible role of nonperturbative effects is also noted.

We revisit LHC searches for heavy invisible particles by exploiting QCD initial state radiation. We recast a dijet signal region in a general multijet plus MET search by ATLAS. We find that the nontrivial mass limit can be obtained for various models of the electroweakino sector with the present data in hadronic channels. The winos are bound to be heavier than $m_{\tilde{W}}\gtrsim 160\mathrm{GeV}$ and Higgsinos $m_{\tilde{h}}\gtrsim 100\mathrm{GeV}$, depending on the chargino-neutralino mass splitting. The expected exclusion limits at the LHC Run 3 with $\mathcal{L}=300{\mathrm{fb}}^{-1}$ increase to $m_{\tilde{W}}\gtrsim 200\mathrm{GeV}$ and $m_{\tilde{h}}\gtrsim 130\mathrm{GeV}$ for winos and Higgsino, respectively. This is the first LHC limit for promptly decaying nearly mass-degenerate winos.

We study lepton flavor violating (LFV) $B$ decays in a general two Higgs doublet model with sub-TeV exotic scalars. Two different parameter spaces are explored: one dominated by extra top Yukawa coupling ${\rho }_{tt}$, the other by LFV couplings relevant for the muon $g-2$ anomaly. In the first case, flavor constraints such as $\ell \to {\ell }^{\prime }\gamma$, $h\to \ell {\ell }^{\prime }$ imply LFV $B$ decays are far below experimental sensitivities. The second case needs to be close to the alignment limit, but $B_q\to \tau \mu$ and $B\to (K,\pi )\tau \mu$ rates can lie within the sensitivities of Belle II and LHCb Upgrade II. Neutral $B$ meson mixings and $B,K,\pi \to \ell \nu$ decays provide important flavor constraints on parameter space. $B$ decays involving $e–\tau$ violation are constrained by $\mu \to e$ processes.

The decay rate of a metastable vacuum is usually calculated using a semiclassical approximation to the Euclidean path integral. The extension to a complete Euclidean lattice Monte Carlo computation, however, is hampered by analytic continuations that are ill-suited to numerical treatment, and the nonequilibrium nature of a metastable state. In this paper we develop a new methodology to compute vacuum decay rates from Monte Carlo simulations of Euclidean lattice theories. To test the new method, we consider simple quantum mechanical systems systems with metastable vacua. This work can be extended to Euclidean field theories, which we discuss in the Conclusions.

We study the Gross-Neveu model in $2+1$ dimensions in an external magnetic field $B$. We first summarize known mean-field results, obtained in the limit of large flavor number $N_{\mathrm{f}}$, before presenting lattice results using the overlap discretization to study one reducible fermion flavor, $N_{\mathrm{f}}=1$. Our findings indicate that the magnetic catalysis phenomenon, i.e., an increase of the chiral condensate with the magnetic field, persists beyond the mean-field limit for temperatures below the chiral phase transition and that the critical temperature grows with increasing magnetic field. This is in contrast to the situation in QCD, where the broken phase shrinks with increasing $B$ while the condensate exhibits a nonmonotonic $B$ dependence close to the chiral crossover, and we comment on this discrepancy. We do not find any trace of inhomogeneous phases induced by the magnetic field.

Within the two-flavor Nambu–Jona-Lasinio model, we derive a self-consistent thermodynamic potential $\mathrm{\Omega }$ for a QCD matter in an external magnetic field $B$. To be consistent with Schwinger’s renormalization spirit, counterterms with vacuum quark mass are introduced into $\mathrm{\Omega }$ and then the explicit $B$-dependent parts can be regularized in a cutoff-free way. Following that, explicit expressions of gap equation and magnetization can be consistently obtained according to the standard thermodynamic relations. The formalism is able to reproduce the paramagnetic feature of a QCD matter without ambiguity. For more realistic study, a running coupling constant is also adopted to account for the inverse magnetic catalysis effect. It turns out that the running coupling would greatly suppress magnetization at large $B$ and is important to reproduce the temperature enhancement effect to magnetization. The case with finite baryon chemical potential is also explored: no sign of first-order transition is found by varying $B$ for the running coupling and the de Haas-van Alphen oscillation shows up in the small $B$ region.

The doubly charged scalar resonance $T_{cs0}^a(2900{)}^{++}$ is studied in the context of the hadronic molecule model. We consider $T_{cs0}^a(2900{)}^{++}$ as a molecule $M=D^{*+}{K}^{*+}$ composed of vector mesons and calculate its mass, current coupling, and full width. The spectroscopic parameters of $M$, i.e., its mass and current coupling, are found by means of the QCD two-point sum rule method by taking into account vacuum expectation values of quark, gluon, and mixed operators up to dimension 10. The width of the molecule $M$ is evaluated through the calculations of the partial widths of the decay channels $M\to D_s^{+}{\pi }^{+}$, $M\to D_s^{*+}{\rho }^{+}$, and $M\to D^{*+}{K}^{*+}$. Partial widths of these processes are determined by strong couplings $g_1$, $g_2$, and $g_3$ of particles at vertices $M{D}_s^{+}{\pi }^{+}$, $M{D}_s^{*+}{\rho }^{+}$, and $M{D}^{*+}{K}^{*+}$, respectively. We calculate the couplings $g_i$ by employing the QCD light-cone sum rule approach and technical tools of the soft-meson approximation. Predictions obtained for the mass $m=(2924\pm 107)\mathrm{MeV}$ and width $\mathrm{\Gamma }=(123\pm 25)\mathrm{MeV}$ of the hadronic molecule $M$ allow us to consider it as a possible candidate of the resonance $T_{cs0}^a(2900{)}^{++}$.

Two near-threshold peaking structures with spin-parities $J^{\mathrm{PC}}=0^{++}$ were recently discovered by the LHCb Collaboration in the $D_s^{+}{D}_s^{-}$ invariant mass distribution of the decay $B^{+}\to D_s^{+}{D}_s^{-}{K}^{+}$. The first of them is the resonance $X(3960)$, whereas the second one, $X_0(4140)$, is a structure with the mass around 4140 MeV. To explore their natures and model them, we study the hadronic molecule $\mathcal{M}=D_s^{+}{D}_s^{-}$ and calculate its mass, current coupling, and width. The mass and current coupling of the molecule are extracted from the QCD two-point sum rule analyses by taking into account vacuum condensates up to dimension 10. To evaluate its full width, we consider the processes $\mathcal{M}\to D_s^{+}{D}_s^{-}$, $\mathcal{M}\to {\eta }_c{\eta }^{(\prime )}$, and $\mathcal{M}\to J/\psi \varphi$. Partial widths of these decays are determined by the strong couplings $g_i,i=1$, 2, 3, 4 at vertices $\mathcal{M}{D}_s^{+}{D}_s^{-}$, $\mathcal{M}{\eta }_c{\eta }^{(\prime )}$, and $\mathcal{M}J/\psi \varphi$. They are computed by means of the three-point sum rule method. Predictions for the mass $m=(4117\pm 85)\mathrm{MeV}$ and width ${\mathrm{\Gamma }}_{\mathcal{M}}=(62\pm 12)\mathrm{MeV}$ of the molecule $\mathcal{M}$ are compared with the corresponding LHCb data, and also with our results for the diquark-antidiquark state $X=[cs][\overline{c}\overline{s}]$. We argue that the structure $X_0(4140)$ may be interpreted as the hadronic molecule $D_s^{+}{D}_s^{-}$, whereas the resonance $X(3960)$ can be identified with the tetraquark $X$.

We compute three-loop corrections to the singlet form factors for massive quarks using a semianalytic method which provides precise results over the whole kinematic range. Particular emphasis is put on the anomaly contribution originating from an external axial-vector current. We also discuss in detail the contribution for a pseudoscalar current and verify the chiral Ward identity to three-loop order. Explicit results are presented for the low- and high-energy regions and the expansions around threshold.

Using a simple eikonal approach to the treatment of Coulomb-nuclear interference and form-factors effects and taking into account the curvature effects in high-energy $pp$ and $\overline{p}p$ scattering, we determine the basic parameters $B$, $\rho$, and ${\sigma }_{\mathrm{tot}}$ from fits to experiment at $W=\sqrt{s}=53\mathrm{GeV}$, 62.3 GeV, 8 TeV, and 13 TeV. We then investigate the differential cross sections in the dip region for $pp$ and $\overline{p}p$ elastic scattering at $W=53\mathrm{GeV}$ and 1.96 TeV. We find that the results of the basic parameters calculated using the simple eikonal approach agree well with the values determined in other analyses. We also find that Coulomb effects are significant in the dip region at 53 GeV and 1.96 TeV, and must be taken into account in searches for odderon effects through cross section differences in that energy region.

Inverse muon decay (${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$) is a promising tool to constrain neutrino fluxes with energies $E_{\nu }\ge 10.9\mathrm{GeV}$. Radiative corrections introduce percent-level distortions to energy spectra of outgoing muons and depend on experimental details. In this paper, we calculate radiative corrections to the scattering processes ${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$ and ${\overline{\nu }}_e{e}^{-}\to {\overline{\nu }}_{\mu }{\mu }^{-}$. We present the muon energy spectrum for both channels, double-differential distributions in muon energy and muon scattering angle and in photon energy and photon scattering angle, and the photon energy spectrum for the dominant ${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$ process. Our results clarify and extend the region of applicability of previous results in the literature for the double differential distribution in muon energy and photon energy, and in the muon energy spectrum with a radiated photon above a threshold energy. We provide analytic expressions for single, double, and triple differential cross sections, and discuss how radiative corrections modify experimentally interesting observable distributions.

We present an updated theoretical treatment of ultraperipheral collisions of heavy ions within the superchic Monte Carlo generator. This in particular accounts for mutual ion excitation through additional photon exchanges between the colliding ions. This effect occurs frequently in ultraperipheral collisions, and indeed can be (and has been) measured in data through the use of zero degree calorimeter detectors installed in the far forward region. The theoretical approach presented here accounts for the nontrivial and non-negligible impact such ion dissociation has on the measured cross sections and distributions of the produced particles in the central detectors. This builds on previous work, whereby the survival factor probability of no additional inelastic ion-ion scattering due to the strong interaction, and its kinematic impact, are also accounted for within the same overall framework. We compare to data from ATLAS and CMS at the LHC, and STAR at RHIC, and find in general encouraging agreement for a range of observables and zero degree calorimeter neutron tags, with some room for further improvement, suggesting the inclusion of higher order QED effects and/or tuning of the $\gamma A\to A^{*}$ cross section may be desirable. Overall, this gives confidence in the approach considered here and for applications to new phenomena within and beyond the Standard Model.

We investigate the general relativistic phase of an electromagnetic wave as it propagates in the gravitational field of the Earth, which is modeled as an isolated, weakly aspherical gravitating body. We introduce coordinate systems to describe light propagation in the Earth’s vicinity along with the relevant coordinate transformations, and discuss the transformations between proper and coordinate times. We represent the Earth’s gravitational field using Cartesian symmetric trace-free (STF) mass multipole moments. The light propagation equation is solvable along the trajectory of a light ray to all STF orders $\ell$. Although we focus primarily on the quadrupole ($\ell =2$), octupole ($\ell =3$), and hexadecapole ($\ell =4$) cases, our approach is valid to all orders. We express the STF moments via spherical harmonic coefficients of various degree and order, $C_{\ell k},S_{\ell k}$. The result is the gravitational phase shift expressed in terms of the spherical harmonics. These results are new. We also consider contributions due to tides and the Earth’s rotation. We estimate the characteristic magnitudes of each term of the resulting overall gravitational phase shift. The terms assessed are either large enough to impact current-generation clocks or will become significant as future-generation clocks offer greater sensitivity. Our formulation is useful for many practical and scientific applications, including space-based time and frequency transfers, relativistic geodesy and navigation, as well as quantum communication links and space-based tests of fundamental physics.

In this work we establish some results concerning the existence of external light rings in extremal black hole spacetimes through the Newman-Penrose formalism. Specifically, assuming flat or (anti)–de Sitter asymptotics, staticity and the null energy condition, we show that a sufficient condition for the existence of external light rings is $R<2K_G$, where $R$, the curvature scalar of the spacetime and $K_G$, the Gaussian curvature of a spacelike two-surface, are both evaluated at the outermost event horizon, which can be endowed with spherical, hyperbolic or planar geometry. Our results are valid for any metric gravity theory where photons follow null geodesics.

In this paper, we discuss on the phenomenological footprints of gauge invariant theories of gravity where the gravitational effects are due not only to spacetime curvature, but also to vectorial nonmetricity. We explore the possibility that vectorial nonmetricity and gauge symmetry may survive after $SU(2)\times U(1)$ (electroweak) symmetry breaking, so that these may have impact on the explanation of certain cosmological puzzles, such as the nature of the dark matter and of the dark energy. We show that this is possible only for theories with gradient nonmetricity, i.e., when the vectorial nonmetricity amounts to a gradient of a scalar. The possibility that vectorial nonmetricity may have played a role in the quantum epoch is not ruled out. We also present an alternative interpretation of gauge invariance of theories with vectorial nonmetricity, which we call the “many-worlds” interpretation due to its overall similitude with the known interpretation of quantum physics.

The velocity of the Sun with respect to the cosmic microwave background (CMB) can be extracted from the CMB dipole, provided its intrinsic dipole is assumed to be small in comparison. This interpretation is consistent, within fairly large error bars, with the measurement of the correlations between neighboring CMB multipoles induced by the velocity of the observer, which effectively breaks isotropy. In contrast, the source number count dipole was reported to privilege a velocity of the observer with an amplitude that is about twice as large as the one extracted from the entirely kinematic interpretation of the CMB dipole, with error bars that indicate a more and more significant tension. In this work, we study the effect of the peculiar velocity of the observer on correlations of nearby multipoles in the source number counts. We provide an unbiased estimator for the kinematic dipole amplitude, which is proportional to the peculiar velocity of the observer and we compute the expected signal-to-noise ratio. Assuming full sky coverage, near future experiments can achieve better than 5% constraints on the velocity of the Sun with our estimator.

We study the observational implications of a class of inflationary models wherein the inflaton is coupled to the Einstein tensor through a generalized nonminimal derivative coupling (GNMDC). In particular, we explore whether these models can generate suitable features in the primordial spectrum of curvature perturbations as a possible explanation for the large-scale anomalies associated with the angular power spectrum of CMB temperature anisotropies. We derive model-independent constraints on the GNMDC function for such a scenario, considering both the scalar and tensor perturbations. We modify cosmomc to accommodate our GNMDC framework and investigate different classes of inflationary models using a fully consistent numerical approach. We find that the hilltop-quartic model with a specific choice of the GNMDC function provides a considerable improvement over the best-fit reference $\mathrm{\Lambda }\mathrm{CDM}$ model with a nearly scale-invariant power spectrum. While the large-scale structure observations should be able to provide independent constraints, future CMB experiments, such as CMB-S4 and CMB-Bharat, are expected to constrain further the parameter space of such beyond canonical single-field inflationary models.

We investigate the entanglement due to geometric corrections in particle creation during inflation. To do so, we propose a single-field inflationary scenario, nonminimally coupled to the scalar curvature of spacetime. We require particle production to be purely geometric, setting to zero the Bogoliubov coefficients and computing the $S$ matrix associated with spacetime perturbations, which are traced back to inflaton fluctuations. The corresponding particle density leads to a nonzero entanglement entropy whose effects are investigated at primordial time of Universe evolution. The possibility of modeling our particle candidate in terms of dark matter is discussed. The classical backreaction of inhomogeneities on the homogeneous dynamical background degrees of freedom is also studied and quantified in the slow-roll regime.

Strong gravitational lensing of gravitational waves (GWs) occurs when the GWs from a compact binary system travel near a massive object. The lensed waveform is given by the product of the lensing amplification factor $F$ and the unlensed waveform. For many axisymmetric lens models such as the point mass and singular isothermal sphere that we consider, $F$ can be calculated in terms of two lens parameters, the lens mass $M_L$ and source position $y$. In the geometrical-optics approximation, lensing in these models produces at most two discrete images which can be parametrized by two image parameters, the flux ratio $I$ and time delay $\mathrm{\Delta }{t}_d$ between images. In the macrolensing regime for which $\mathrm{\Delta }{t}_d$ is large compared to the time $T$ they spend within the sensitivity band of GW detectors, it is natural to parametrize lensing searches in terms of these image parameters. The functional dependence of the lensed signal on these image parameters is far simpler, facilitating data analysis for events with modest signal-to-noise ratios, and constraints on $I$ and $\mathrm{\Delta }{t}_d$ can be inverted to constrain $M_L$ and $y$ for any lens model. We propose that this use of image parameters can be extended to the microlensing regime ($\mathrm{\Delta }{t}_d<T$) in which the two interfering images are observed as a single GW event. We use image parameters to determine the detectability of gravitational lensing in GW the microlensing regime and find that for GW events with signal-to-noise ratios $\rho$ and total mass $M$, lensing should in principle be identifiable for flux ratios $I\gtrsim 2{\rho }^{-2}$ and time delays $\mathrm{\Delta }{t}_d\gtrsim M^{-1}$.

We systematically calculate the axion-photon coupling for nonminimal Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) models. Thereby, we can classify every calculated model and study the resulting distributions, relevant for axion experiments like haloscopes, helioscopes, or light-shining-through-a-wall experiments. By adding more than one additional Higgs doublet, these nonminimal DFSZ models extend the viable axion parameter space and lead to a large range of axion-photon couplings. We find couplings almost 3 orders of magnitude larger than the ones of the minimal models. Most of the possible axion-photon couplings, however, lie in the vicinity of the values dictated by the minimal models. We quantify this by introducing a theoretical prior probability distribution for DFSZ-type axions and giving 68% and 95% lower bounds as well as two-sided bands. We compare our results for the DFSZ axion-photon coupling distributions with the Kim-Shifman-Vainshtein-Zakharov case, for which a similar analysis has been conducted. Both display similar values as well as a very specific pattern. In order to identify preferred models, we discuss the role of flavor changing neutral currents and the domain wall problem as possible selection criteria. It is possible to construct a large number of nonminimal DFSZ models with a domain wall number of unity, thereby avoiding the domain wall problem. This subset also has a significantly enhanced axion-photon coupling compared to the minimal DFSZ models.