We study the phenomenology of a particular leptoquark extension of the Standard Model (SM), namely the doublet-singlet scalar leptoquark extension of the SM (DSL-SM). Besides generating Majorana mass for neutrinos, these leptoquarks contribute to muon and electron ($g-2$) and various lepton flavor violating processes. Collider signatures of the benchmark points (BPs), consistent with the neutrino oscillation data, anomalous muon/electron magnetic moments, experimental bounds on the charged lepton flavor violation observables, etc., are studied at the LHC/FCC with center-of-mass energies of 14, 27 and 100 TeV. While the two $-1/3$ charged colored scalars from the singlet and the doublet leptoquark mix with each other, the charge $2/3$ colored scalar from the doublet leptoquark remains pure. With a near-degenerate mass spectrum, the pure and mixed leptoquark states are shown to be distinguishable from multiple final states, while discerning between the two mixed states remains very challenging.

In this work, we consider an extension of the Standard Model with an inert Higgs doublet and a real scalar singlet, in order to address problems around the origin of dark matter (DM). In this model, the lightest among the $CP$-odd and $CP$-even neutral inert components plays the role of a DM candidate, where the model parameters are subject to many theoretical and experimental constraints. These constraints include vacuum stability, perturbativity, LEP negative searches, electroweak precision tests, Higgs diphoton, Higgs invisible and Higgs undetermined decays, DM relic density, and DM direct detection bounds. Using these constraints, we find that the allowed parameter space for these models is quite sizable and could be explored in upcoming collider and astrophysical searches.

Most studies of Higgs sector $CP$ violation focus on the detection of $CP$-violating neutral Higgs-fermion Yukawa couplings, which yield $P$-odd, $CP$-violating phenomena. There is some literature on purely bosonic signatures of Higgs sector $CP$ violation, where the simultaneous observation of three processes (suitably chosen) constitutes a signal of $P$-even $CP$ violation. However, in the examples previously analyzed, some of the processes are strongly suppressed in the approximate Higgs alignment limit (corresponding to the existence of a Standard Model-like Higgs boson as suggested by LHC data), in which case the proposed $CP$-violating signals are difficult to observe in practice. In this paper, we extend the existing literature by examining processes that do not vanish in the Higgs alignment limit and whose simultaneous observation would provide unambiguous evidence for scalar-mediated $P$-even $CP$ violation. We assess the discovery potential of such signals at various future multi-TeV lepton (and $\gamma \gamma$) colliders. The potential for detecting loop-induced $P$-even, $CP$-violating phenomena is also considered.

We revisit minimal nonsupersymmetric models of $SU(5)$ grand unification with the type II seesaw mechanism as the origin of neutrino masses. Imposing the requirement of gauge coupling unification and the proton lifetime bounds, we perform a Bayesian fit and obtain robust quantitative information on the mass scales of the beyond the Standard Model particles. We then study lepton-flavor-violating processes induced by the type II scalar triplet and its $SU(5)$ partners, showing that the interplay of upcoming searches for different lepton-flavor-violating observables can provide additional information on the masses of the new particles, as well as nontrivial constraints on neutrino parameters.

We extend a previously developed approach to relate thermal currents in the high temperature regime and classical limits of amplitudes. We consider the biadjoint scalar theory, which has the basic structure of a cubic theory and which is related to QCD and gravity through the double copy. In addition, we consider a generalization of scalar QED to model classical spin, where massive scalars are complex higher-spin fields. We derive Vlasov-type kinetic equations for biadjoint scalars and study their iterative solutions, while for QED we use well-known kinetic equations. In both cases we find consistency between these solutions and the amplitudelike approach.

We present multiple results on the production of loosely bound molecules in bottomonium annihilations and $e^{+}{e}^{-}$ collisions at $\sqrt{s}=10.58\mathrm{GeV}$. We perform the first comprehensive test of several models for deuteron production against all the existing data in this energy region. We fit the free parameters of the models to reproduce the observed cross sections, and we predict the deuteron spectrum and production and the cross section for the $e^{+}{e}^{-}\to d\overline{d}+X$ process both at the $\mathrm{\Upsilon }(1,2,3S)$ resonances and at $\sqrt{s}=10.58\mathrm{GeV}$. The predicted spectra show differences but are all compatible with the uncertainties of the existing data. These differences could be addressed if larger datasets are collected by the Belle II experiment. Fixing the source size parameter to reproduce the deuteron data, we then predict the production rates for $H$ dibaryon and hypertriton in this energy region using a simple coalescence model. Our prediction on the $H$ dibaryon production rate is below the limits set by the direct search at the Belle experiment, but in the range accessible to the Belle II experiment. The systematic effect due to the MC modeling of quarks and gluon fragmentation into baryons is reduced, deriving a new tuning of the pythia 8 Monte Carlo generator using the available measurement of single- and double-particle spectra in $\mathrm{\Upsilon }$ decays.

Imbalanced beauty-charmed baryons ${\mathrm{\Xi }}_{bc}^{+,0}$ are of great significance to the development of heavy flavor physics. In this work, we study the inclusive weak-annihilation decays of ${\mathrm{\Xi }}_{bc}^{+,0}$ and their contributions to the ${\mathrm{\Xi }}_{bc}^{+,0}$ lifetimes. For the calculation of the inclusive ${\mathrm{\Xi }}_{bc}^{+,0}\to X_{cs}$ decay width where $X_{cs}$ stands for the sum of the final states with charm number $+1$ and strange number $-1$, we work in the heavy diquark effective theory, which provides us with a convenient technical tool to construct the operator product expansion. The ${\mathrm{\Xi }}_{bc}^{+,0}$ is considered to be a superposition of two states with one containing a spin-0 $bc$ diquark and the other one containing a spin-1 $bc$ diquark. It is found that both the ${\mathrm{\Xi }}_{bc}^{+,0}$ lifetimes and the ${\mathrm{\Xi }}_{bc}^{+,0}\to X_{cs}$ branching ratios are very sensitive to the $bc$ spin in ${\mathrm{\Xi }}_{bc}^{+,0}$. The ${\mathrm{\Xi }}_{bc}^{+,0}\to X_{cd}$ results are also presented. As ${\mathrm{\Xi }}_{bc}^{+}$ has a longer lifetime than ${\mathrm{\Xi }}_{bc}^0$ and bigger branching ratios of similar decay channels, the exclusive decays ${\mathrm{\Xi }}_{bc}^{+}\to D^{(*)+}\mathrm{\Lambda }$, ${\mathrm{\Xi }}_{bc}^{+}\to {\mathrm{\Lambda }}_c^{+}{\overline{K}}^{(*)0}$, ${\mathrm{\Xi }}_{bc}^{+}\to D^{(*)+}{K}^{-}p$, and ${\mathrm{\Xi }}_{bc}^{+}\to D^0{\overline{K}}^{(*)0}p$ are more promising for experimental searches of ${\mathrm{\Xi }}_{bc}^{+,0}$ at the LHC comparing with exclusive decay ${\mathrm{\Xi }}_{bc}^0\to D^{0}p{K}^{-}$.

A brief review of the available experimental and theoretical results on the production of the ${\chi }_{Q1}$ states in $e^{+}{e}^{-}$ annihilation and photon-photon $\gamma {\gamma }^{*}$ interactions is presented. Future data on the production of the ${\chi }_{c1}(1P)$, ${\chi }_{c1}(3872)$, ${\chi }_{c1}(4140)$, ${\chi }_{c1}(4274)$, ${\chi }_{c1}(4685)$, ${\chi }_{b1}(1P)$, ${\chi }_{b1}(2P)$, and ${\chi }_{b1}(3P)$ resonances in $e^{+}{e}^{-}$ annihilation and $\gamma {\gamma }^{*}$ interactions will help the development and unification of theoretical predictions related to the electroweak decays of heavy quarkonia, the reduction of their spread and model uncertainties.

Precision measurement of quark Yukawa couplings is a crucial aspect of the Higgs property study. Proposed as a future upgrade of the Large Hadron Collider (LHC), the Large Hadron electron Collider (LHeC) provides opportunities to probe quark Yukawa couplings with a high precision because of relatively low QCD background as compared with that of the Higgs processes at the LHC. For this purpose, it is important to have a precision prediction of the Higgs production rate at the LHeC. The leading production channel of the Higgs boson at the LHeC is via weak boson fusion (WBF) which has the unique kinematic feature of forward tagging jets. As QCD corrections are suppressed by the simple color structure of the process, electroweak (EW) radiative corrections become particularly important. In this paper, we focus on the EW radiative corrections at next-to-leading order for the Higgs-boson production via charge current WBF processes at the LHeC. In the two renormalization schemes we use, the EW corrections are respectively at the level of 9% and 18% relative to the leading order result, for a center-of-mass energy at 1.98 TeV, and the next-to-leading order results in both schemes agree up to a truncation error expected from the perturbative method. The size of the EW corrections exceeds that from QCD radiations and is shown to be important for the study of Higgs phenomenology.

We describe the implications of permutation symmetry for the state space and dynamics of quantum mechanical systems of matrices of general size $N$. We solve the general 11-parameter permutation invariant quantum matrix harmonic oscillator Hamiltonian and calculate the canonical partition function. The permutation invariant sector of the Hilbert space, for general Hamiltonians, can be described using partition algebra diagrams forming the bases of a tower of partition algebras $P_k(N)$. The integer $k$ is interpreted as the degree of matrix oscillator polynomials in the quantum mechanics. Families of interacting Hamiltonians are described which are diagonalized by a representation theoretic basis for the permutation invariant subspace which we construct for $N\ge 2k$. These include Hamiltonians for which the low-energy states are permutation invariant and can give rise to large ground state degeneracies related to the dimensions of partition algebras. A symmetry-based mechanism for quantum many body scars discussed in the literature can be realized in these matrix systems with permutation symmetry. A mapping of the matrix index values to lattice sites allows a realization of the mechanism in the context of modified Bose-Hubbard models. Extremal correlators analogous to those studied in $\mathrm{AdS}/\mathrm{CFT}$ are shown to obey selection rules based on Clebsch-Gordan multiplicites (Kronecker coefficients) of symmetric groups.

We consider local semitransparent Neumann boundary conditions for a quantum scalar field as imposed by a quadratic coupling to a source localized on a flat codimension-one surface. Upon a proper regularization to give meaning to the interaction, we interpret the effective action as a theory in a first-quantized phase space. We compute the relevant heat kernel to all order in a homogeneous background and quadratic order in perturbations, giving a closed expression for the corresponding effective action in $D=4$. In the dynamical case, we analyze the pair production caused by a harmonic perturbation and a Sauter pulse. Notably, we prove the existence of a strong/weak duality that links this Neumann field theory to the analog Dirichlet one.

We introduce a convenient set of analytical tools (the Gaussian formalism) and diagrams (symplectic circuits) to analyze multimode scattering events in analogue gravity, such as pair creation à la Hawking by black hole and white hole analogue event horizons. The diagrams prove to be valuable Ansätze for the scattering dynamics, especially in settings where direct analytic results are not straightforward and one must instead rely on numerical simulations. We use these tools to investigate entanglement generation in single- and multihorizon scenarios, in particular when the Hawking process is stimulated with classical (e.g., thermal noise) and nonclassical (e.g., single-mode squeezed vacuum) input states—demonstrating, for instance, that initial squeezing can enhance the production of entanglement and overcome the deleterious effects that initial thermal fluctuations have on the output entanglement. To make further contact with practical matters, we examine how attenuation degrades quantum correlations between Hawking pairs. The techniques that we employ are generally applicable to analogue gravity setups of (Gaussian) bosonic quantum systems, such as analogue horizons produced in optical analogues and in Bose-Einstein condensates, and should be of great utility in these domains. We show the applicability of these techniques by putting them in action for an optical system containing a pair white-black hole analogue, extending our previous analysis of [Phys. Rev. Lett. 128, 091301 (2022)].

Motivated by recent numerical relativity simulations of charged black holes and their interactions, we explore the properties of common slicing conditions in Reissner-Nordström spacetimes. Specifically, we consider different choices for the so-called Bona-Massó function and construct static and spherically symmetric slices of the Reissner-Nordström spacetime satisfying the corresponding slicing conditions. For some of these functions the construction is entirely analytical, while for others we use numerical root-finding to solve quartic equations. Our solutions are parametrized by the charge-to-mass ratio $\lambda =Q/M$ and approach a unique slice, independent of the Bona-Massó functions considered here, in the extremal limit $\lambda \to 1$.

We revisit the numerical evolution of Ellis-Bronnikov-Morris-Thorne wormholes, which are constructed with a massless real ghost scalar field. For our simulations, we have developed a new code based on the standard $3+1$ foliation of spacetime. We confirm that, for the massless symmetric wormhole, a pulse of regular scalar field causes the wormhole throat to collapse and form an apparent horizon, while a pulse of ghost scalar field can cause the wormhole throat to expand. As a new result, we show that it is possible for a pulse of regular matter to travel through the wormhole and then to send a light signal back before the wormhole collapses. We also evolve pulses of matter traveling through massive asymmetric wormholes, which has not previously been simulated.

We revisit the predictions for the duration of the inflationary phase after the bounce in loop quantum cosmology. We present our analysis for different classes of inflationary potentials that include the monomial power-law chaotic type of potentials, the Starobinsky and the Higgs-like symmetry breaking potential with different values for the vacuum expectation value. Our setup can easily be extended to other forms of primordial potentials than the ones we have considered. Independently on the details of the contracting phase, if the dynamics starts sufficiently in the far past, the kinetic energy will come to dominate at the bounce, uniquely determining the amplitude of the inflaton at this moment. This will be the initial condition for the further evolution that will provide us with results for the number of $e$-folds from the bounce to the beginning of the accelerated inflationary regime and the subsequent duration of inflation. We also discuss under which conditions each model considered could lead to observable signatures on the spectrum of the cosmic microwave background or else be excluded for not predicting a sufficient amount of accelerated expansion. A first analysis is performed considering the standard value for the Barbero-Immirzi parameter, $\gamma \simeq 0.2375$, which is obtained from black hole entropy calculations. In a second analysis, we consider the possibility of varying the value of this parameter, which is motivated by the fact that the Barbero-Immirzi parameter can be considered a free parameter of the underlying quantum theory in the context of loop quantum gravity. From this analysis, we obtain a lower limit for this parameter by requiring the minimum amount of inflationary expansion that makes the model consistent with the cosmic microwave background observations. When constraining the Barbero-Immirzi parameter, we have made use of the results for the scalar of curvature perturbations derived in loop quantum cosmology assuming the dressed metric approach and considering the Bunch-Davies vacuum as the initial condition for the perturbations in the contracting phase. Such choice provides basically the same results as considering the fourth-order adiabatic vacuum state at the bounce as an initial condition in the context of the dressed metric approach.

The power spectrum and the voxel intensity distribution (VID) are two of the main proposed summary statistics to study line-intensity maps. We reformulate the derivation of the VID in terms of the local overdensities and derive for the first time an analytic covariance between the VID and the line-intensity mapping power spectrum. We study the features of this covariance for different experimental setups and show that we can recover similar results to simulation-based covariances. With this formalism, we also compute the cosmic variance contribution to the VID uncertainty, which we find to be subdominant with respect to the standard variance from Poisson sampling. Our results allow for general joint analyses of the VID and the line-intensity mapping power spectrum.

We present a formulation of cosmological-perturbation theory where the Boltzmann hierarchies that evolve the neutrino phase-space distributions are replaced by integrals that can be evaluated easily with fast Fourier transforms. The simultaneous evaluation of these integrals combined with the differential equations for the rest of the system (dark matter, photons, baryons) are then solved with an iterative scheme that converges quickly. The formulation is particularly powerful for massive neutrinos, where the effective phase space is three dimensional rather than two dimensional, and even more so for three different neutrino mass eigenstates. Therefore, it has the potential to significantly speed up the computation times of cosmological-perturbation calculations. This approach should also be applicable to models with other noncold collisionless relics.

Recently, it has been found that complete resolution of the Hubble tension might point to a scale-invariant Harrison-Zeldovich spectrum of primordial scalar perturbation, i.e., $n_s=1$ for $H_0\sim 73\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$. We show that, for well-known slow-roll models, if inflation ends by a waterfall instability with respect to another field in the field space while inflaton is still at a deep slow-roll region, then $n_s$ can be lifted to $n_s=1$. A surprise of our result is that with prerecombination early dark energy, chaotic ${\varphi }^2$ inflation, strongly disfavored by $\mathrm{Planck}+\mathrm{BICEP}/\mathrm{Keck}$ in standard $\mathrm{\Lambda }\mathrm{CDM}$, can be revived, which is now well within testable region of upcoming cosmic microwave background B-mode experiments.