We develop a search strategy for a heavy Majorana neutrino via the lepton number violation signal process $p{e}^{-}\to {\mu }^{+}jjj$ at future electron-proton colliders. The signal and dominant standard model background events are generated with a fast detector simulation. We apply the preselection criteria and perform a multivariate analysis based on machine learning to reject the background. Distributions of representative kinematic observables are presented for both signal and background processes, and effects on final limits are compared by inputting two different sets of observables when performing multivariate analysis. The $2\sigma$ and $5\sigma$ limits on the mixing parameter $|V_{\ell N}{|}^2$ are predicted for the heavy neutrino mass $m_N$ in the range of 10–1000 GeV. At the LHeC (FCC-eh) with an electron beam energy of 60 GeV, a proton beam energy of 7 (50) TeV, and an integrated luminosity of 1 $(3){\mathrm{ab}}^{-1}$, the mixing parameter $|V_{\ell N}{|}^2$ can be constrained to be below $\sim 3.0(1.0)\times {10}^{-6}$ for $m_N$ around $\mathcal{O}(100)\mathrm{GeV}$ at $2\sigma$ level. The limits are much stronger than the current experiment limits at the LHC for $m_N$ above 30 GeV. The positron signal final state and the effect of long-lived cases of heavy neutrinos are also checked and commented.

We study a lepton portal dark matter model, motivated by the deviation of the $W$ boson mass reported by the CDF collaboration. We introduce vectorlike leptons and a scalar dark matter (DM) that exclusively couples to the extra leptons and muon. The one-loop corrections induced by the new particles can shift the $W$ boson mass. Besides, the discrepancy in the muon anomalous magnetic moment and the DM density can simultaneously be explained by this setup, if the vectorlike lepton is lighter than 200 GeV and nearly degenerate with the DM particle. We also see that the constraints on such a light extra lepton from the collider experiments can be evaded due to the existence of the DM particle.

I make some simple observations about the calculation of weighted averages over energy of Minkowski space spectral densities from weighted averages over time of Euclidean space correlation functions, measured in lattice simulations. The correlator of two vector currents is used as an example, where it appears that a determination of a weighted average of the spectral function near the rho pole at the five percent level is possible from lattice simulations.

We initiate the studies on the structural physics of the tower of stable large-$N_c$ mesons through a first computation of the collinear quark structure of a large-$N_c$ pion using lattice Monte Carlo methods. We adapt the large-$N_c$ continuum reduction for the determination of meson correlation functions involving the spatially extended quasiparton distribution function operators as a perfect strategy to concentrate only on the short perturbative length scales. We find the internal structures of a pion in the large-$N_c$ and $N_c=3$ theories to be quite similar. Interestingly, we find hints that even the observed differences could arise to a large extent via the different perturbative QCD evolution in the two theories from similar initial conditions at low-factorization scales.

We examine the constraining power of current gravitational-wave data on scalar-tensor-Gauss-Bonnet theories that allow for the spontaneous scalarization of black holes. In the fiducial model that we consider, a slowly rotating black hole must scalarize if its size is comparable to the new length scale $\lambda$ that the theory introduces, although rapidly rotating black holes of any mass are effectively indistinguishable from their counterparts in general relativity. With this in mind, we use the gravitational-wave event GW190814—whose primary black hole has a spin that is bounded to be small, and whose signal shows no evidence of a scalarized primary—to rule out a narrow region of the parameter space. In particular, we find that values of $\lambda \in [56,96]M_{\odot }$ are strongly disfavored with a Bayes factor of 0.1 or less. We also include a second event, GW151226, in our analysis to illustrate what information can be extracted when the spins of both components are poorly measured.

We study the superradiant instability in scalar-tensor theories of gravitation, where matter outside a black hole provides an effective mass to the scalar degree of freedom of the gravitational sector. We discuss this effect for arbitrarily spinning black holes and for realistic models of truncated thin and thick accretion disks (where the perturbation equations are nonseparable), paying particular attention to the role of hot coronal flows in the vicinity of the black hole. The system qualitatively resembles the phenomenology of plasma-driven superradiant instabilities in general relativity. Nevertheless, we show that the obstacles hampering the efficiency of plasma-driven superradiant instabilities in general relativity can be circumvented in scalar-tensor theories. We find a wide range of parameter space where superradiant instabilities can be triggered in realistic scenarios, and discuss the constraints on scalar-tensor theories imposed by this effect. In particular, we argue that the existence of highly spinning accreting black holes is in tension with some scalar-tensor alternatives to the dark energy, e.g., symmetron models with screening.

Dark matter and inflation are two key elements to understand the origin of cosmic structures in modern cosmology, and yet their exact physical models remain largely uncertain. The Weyl scaling invariant theory of gravity may provide a feasible scheme to solve these two puzzles jointly, which contains a massive gauge boson playing the role of dark matter candidate and allows the quadratic scalar curvature term, namely $R^2$, to realize a viable inflationary mechanism in agreement with current observations. We ponder on the production of dark matter in the Weyl $R^2$ model, including the contribution from the nonperturbative production due to the quantum fluctuations from inflationary vacuum and perturbative ones from scattering. We demonstrate that there are generally three parameter regions for viable dark matter production: (1) If the reheating temperature is larger than ${10}^3\mathrm{GeV}$, then the Weyl gauge boson as dark matter can be produced abundantly with mass larger than the inflation scale $\sim {10}^{13}\mathrm{GeV}$. (2) Small mass region with $3\times {10}^{-13}\mathrm{GeV}$ for a higher reheating temperature. (3) Annihilation channel becomes important in the case of higher reheating temperature, which enables the Weyl gauge boson with a mass up to $4\times {10}^{16}\mathrm{GeV}$ to be produced through freeze-in.

Elastic self-scatterings do not change the number of dark matter particles and as such have been neglected in the calculation of its relic abundance. In this work we highlight the scenarios where the presence of self-scatterings has a significant impact on the effectiveness of annihilation processes through the modification of dark matter momentum distribution. We study a few example freeze-out scenarios involving resonant and subthreshold annihilations, as well as a model with an additional source of dark matter particles from the decays of a heavier mediator state. Interestingly, when the calculation is performed at the level of dark matter momentum distribution function, we find that the injection of additional energetic dark matter particles onto the thermal population can lead to a decrease of its final relic abundance.

We study the astrophysical implications of the quark nugget model of dark matter and propose observational techniques for detecting antiquark nuggets (anti-QNs) with modern telescopes. Anti-QNs are compact composite objects of antiquark matter with a typical radius $R\sim {10}^{-5}\mathrm{cm}$ and density exceeding that of nuclear matter. Atoms and molecules of interstellar medium collide with antiquark nuggets and annihilate. We estimate thermal radiation from anti-QNs in cold molecular clouds in our Galaxy and show that this radiation appears sufficiently strong to be observed in infrared and visible spectra. Proton annihilation on anti-QNs produces $\gamma$ photons with energies in the range 100–400 MeV, which may be detected by telescopes such as Fermi-LAT. We have found that anti-QN radiation inside the solar corona is too weak to produce a significant plasma heating or any other observable effects, while the radiation of $\gamma$ photons from the chromosphere may be observable. We also address the problem of survival of antiquark nuggets in the early Universe.

The CDF collaboration has recently published a precision measurement of the $W$-boson mass that differs from the Standard Model prediction by seven standard deviations. This result can be explained with additional electroweak multiplets that either break the custodial symmetry or contribute to oblique parameters at loop level. Here, we study one of the best-motivated scenarios involving new multiplets: the type-II seesaw model, which involves a scalar triplet that generates Majorana neutrino masses and can furthermore resolve the $W$-boson mass discrepancy. This favors a doubly charged scalar with mass between 100 and 200 GeV as well as other scalars with a fixed mass splitting. The entire preferred parameter space is testable at the LHC.

We present a model explaining both the $4.2\sigma$ muon $g-2$ anomaly and the relic density of dark matter (DM) in which DM interacts with the Standard Model (SM) via a scalar portal boson $\phi$ carrying both dark and SM leptonic numbers, and mediating a nondiagonal interaction between the electron and muon that allows $e\leftrightarrow \mu$ transitions. The $\phi$ could be produced in high-energy electron scattering off a target nuclei in the reaction $eZ\to \mu Z\phi$ followed by the prompt invisible decay $\phi \to \mathrm{DM}$ particles and searched for in events with large missing energy accompanied by a single outgoing muon in the final state. Interestingly, several events with a similar signature have been observed in a data sample of $\simeq 3\times {10}^{11}$ electrons on target collected during 2016-2018 for the search for light dark matter in the NA64 experiment at the CERN SPS [D. Banerjee et al. (NA64 Collaboration), Phys. Rev. Lett. 123, 121801 (2019).]. Attributing so far these events to background allows us to set first constraints on the $\phi$ mass and couplings while leaving at the same time decisively probing the origin of these events and a large fraction of the remaining parameter space to a near exiting future with the upgraded NA64 detector or other planned experiments.

As low-threshold dark matter detectors advance in development, they will become sensitive to recoils from solar neutrinos which opens up the possibility to explore neutrino properties. We predict the enhancement of the event rate of solar neutrino scattering from beyond the Standard Model interactions in low-threshold DM detectors, with a focus on silicon, germanium, gallium arsenide, xenon, and argon-based detectors. We consider a set of general neutrino interactions, which fall into five categories: the neutrino magnetic moment as well as interactions mediated by four types of mediators (scalar, pseudoscalar, vector, and axial vector), and consider coupling these mediators to either quarks or electrons. Using these predictions, we place constraints on the mass and couplings of each mediator and the neutrino magnetic moment from current low-threshold detectors like SENSEI, Edelweiss, and SuperCDMS, as well as projections relevant for future experiments such as DAMIC-M, Oscura, Darwin, and ARGO. We find that such low-threshold detectors can improve current constraints by up to two orders of magnitude for vector mediators and one order of magnitude for scalar mediators.

The fully charm and bottom pentaquarks, i.e., $cccc\overline{c}$ and $bbbb\overline{b}$, with spin-parity quantum numbers $J^P={\frac{1}{2}}^{-}$, ${\frac{3}{2}}^{-}$, and ${\frac{5}{2}}^{-}$, are investigated within a lattice-QCD inspired quark model, which has already successfully described the recently announced fully charm tetraquark candidate $X(6900)$ and has also predicted several other fully heavy tetraquarks. A powerful computational technique, based on the Gaussian expansion method combined with a complex-scaling range approach, is employed to predict, and distinguish, bound, resonance, and scattering states of the mentioned five-body system. Both baryon-meson and diquark-diquark-antiquark configurations, along with all of their possible color channels are comprehensively considered. Narrow resonances are obtained in each spin-parity channel for the fully charm and bottom systems. Moreover, most of them seem to be compact multiquarks whose wave functions are dominated by either hidden-color baryon-meson or diquark-diquark-antiquark structure or by the coupling between them.

We complete the calculation of the three-gluon-emission contribution to the same-hemisphere part of the zero-jettiness soft function at next-to-next-to-next-to-leading order in perturbative QCD.

In this paper we calculate first order radiative QCD corrections to the decay process $b\to c{W}^{-}(\to {\ell }^{-}{\overline{\nu }}_{\ell })$ of a polarized bottom quark. Taking into account both the bottom and charm quark masses, the analytical expressions given in this paper allow for a detailed analysis of the differential decay rate of the polarized quark in dependence on the polar and azimuthal angles of the lepton pair and the angle of the polarization vector of the quark relative to the momentum direction of the $W$ boson. The results are given for different polarization states of the charged lepton. In addition, we calculated nonperturbative corrections and estimated their contribution.

We explore the prospect of constraining light mediators at the next generation direct detection dark matter detectors through coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) and elastic neutrino-electron scattering ($\mathrm{E}\nu \mathrm{ES}$) measurements. Taking into account various details like the quenching factor corrections, atomic binding effects, realistic backgrounds, detection efficiency, energy resolution, etc., we consider two representative scenarios regarding detector specifications. For both scenarios, we obtain the model-independent projected sensitivities for all possible Lorentz-invariant interactions, namely, scalar ($S$), pseudoscalar ($P$), vector ($V$), axial vector ($A$), and tensor ($T$). For the case of vector interactions, we also focus on two concrete examples: the well-known $U(1{)}_{B-L}$ and $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge symmetries. For all interaction channels $X=\{S,P,V,A,T\}$, our results imply that the upcoming dark matter detectors have the potential to place competitive constraints, improved by about 1 order of magnitude compared to existing ones from dedicated $\mathrm{CE}\nu \mathrm{NS}$ experiments, XENON1T, beam dump experiments, and collider probes.

A search for Kaluza-Klein excited vector boson resonances, $W_{\mathrm{KK}}$, decaying in cascade to three $W$ bosons via a scalar radion $R$, $W_{\mathrm{KK}}\to WR\to WWW$, in a final state containing two or three massive jets is presented. The search is performed with $\sqrt{s}=13\mathrm{TeV}$ proton-proton collision data collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of $138{\mathrm{fb}}^{-1}$. Two final states are simultaneously probed, one where the two $W$ bosons produced by the $R$ decay are reconstructed as separate, large-radius, massive jets, and one where they are merged into a single large-radius jet. The observed data are in agreement with the standard model expectations. Limits are set on the product of the $W_{\mathrm{KK}}$ resonance cross section and branching fraction to three $W$ bosons in an extended warped extra-dimensional model and are the first of their kind at the LHC.

We consider the generators of gauge transformations with test functions which do not vanish on the boundary of a spacelike region of interest. These are known to generate the edge degrees of freedom in a gauge theory. In this paper, we augment these by introducing the dual or magnetic analog of such operators. We then study the algebra of these operators, focusing on implications for the superselection sectors of the gauge theory. A manifestly duality-invariant action is also considered, from which alternate descriptions which are $SL(2,\mathbb{Z})$ transforms of each other can be obtained. We also comment on a number of issues related to local charges, definition of confinement and the appearance of interesting mathematical structures such as the Drinfel’d double and the Manin triple.

We generalize our recent method for constructing Killing tensors of the second rank to conformal Killing tensors. The method is intended for foliated spacetimes of arbitrary dimension $m$, which have a set of conformal Killing vectors. It applies to foliations of a more general structure than in previous literature. The primary idea is to start with a Killing tensor reducible in the foliation slices and lift it to the whole manifold using a system of differential equations. The integrability conditions permitting this lift are derived, and a constructive lifting procedure is presented. The resulting conformal Killing tensor may be irreducible. It is shown that subdomains of foliation slices suitable for the method are fundamental photon surfaces if some additional photon region inequality is satisfied. Thus our procedure also opens the way to obtain a simple general analytical expression for the boundary of the gravitational shadow. We apply this technique to electrovacuum, and $\mathcal{N}=2$, 4, 8 supergravity black holes, providing a new easy way to establish the existence of exact and conformal Killing tensors.

A pulsar timing array (PTA) is expected to detect a gravitational wave background (GWB) in the nanohertz band within the next decade. This provides an opportunity for one to test gravity theory and cosmology. A typical data analysis method to detect GWB is cross-correlation analysis. The overlap reduction function (ORF) plays an important role in the correlation data analysis of GWB. The present approach to dealing with the intricate integration in ORF is to use short-wave approximation to drop out the tricky terms. In this paper, we provide the full analytic expression of the ORF for PTA without any approximation for all possible polarizations allowed by modifications of general relativity. Compared with the numerical simulation and short-wave approximation, our results are more efficient and widely applicable. Especially for the scalar-longitudinal mode where the short-wave approximation is not available, our analytical expression is particularly significant.