We study first-order electroweak phase transitions in the real-singlet-extended Standard Model, for which nonzero mixing between the Higgs field and the singlet can efficiently strengthen the transitions. We perform large-scale parameter-space scans of the model using two-loop effective potential at next-to-next-to-leading order in the high-temperature expansion, greatly improving description of phase transition thermodynamics over existing one-loop studies. We find that (1) two-loop corrections to the effective potential lead to narrower regions of strong first-order transitions and significantly smaller critical temperatures, (2) transitions involving a discontinuity in the singlet expectation value are significantly stronger at two-loop order, and (3) high-temperature expansion is accurate for a wide range of parameter space that allows strong transitions, although it is less reliable for the very strongest transitions. These findings suggest revisiting past studies that connect the possibility of a first-order electroweak phase transition with future collider phenomenology.

The seesaw mechanism with three heavy Majorana right-handed neutrinos provides an elegant explanation for neutrino masses and, combined with leptogenesis, can generate the baryon asymmetry of the universe (BAU). Naturally embedded in a grand unified theory, this framework stands as one of the best-motivated extensions beyond the Standard Model, but it is very difficult to test it. Moreover, it does not account for dark matter (DM). In this paper, we propose a minimal extension that introduces a dark sector with a singlet Majorana fermion (as the DM candidate) and a complex scalar singlet. The heavy right-handed neutrinos serve another role beyond generating neutrino masses and the BAU: producing the cold DM density through their decays. Interestingly, the model also predicts a subdominant DM component from late scalar decays, which in some cases may be hot or warm at the onset of structure formation, as well as an equal number of nonthermal neutrinos. These components leave distinct signatures in various cosmological observables. Furthermore, electromagnetic energy injection from scalar decays alter predictions from big bang nucleosynthesis and induce spectral distortions in the cosmic microwave background black-body spectrum. In this context, upcoming experiments, such as the Primordial Inflation Explorer (PIXIE), could probe the mechanism of neutrino mass generation.

Nonequilibrium Markov chain Monte Carlo (NE-MCMC) simulations provide a well-understood framework based on Jarzynski’s equality to sample from a target probability distribution. By driving a base probability distribution out of equilibrium, observables are computed without the need to thermalize. If the base distribution is characterized by mild autocorrelations, this approach provides a way to mitigate critical slowing down. Out-of-equilibrium evolutions share the same framework of flow-based approaches and they can be naturally combined into a novel architecture called stochastic normalizing flows (SNFs). In this work we present the first implementation of SNFs for SU(3) lattice gauge theory in 4 dimensions, defined by introducing gauge-equivariant layers between out-of-equilibrium Monte Carlo updates. The core of our analysis is focused on the promising scaling properties of this architecture with the degrees of freedom of the system, which are directly inherited from NE-MCMC. Finally, we discuss how systematic improvements of this approach can realistically lead to a general and yet efficient sampling strategy at fine lattice spacings for observables affected by long autocorrelation times.

We reanalyze, considering the contribution of $P$-wave charmonia, lattice data for the $D\overline{D}–D_s{\overline{D}}_s$ coupled-channel of Prelovsek et al. [J. High Energy Phys. 06 (2021) 035.] and $D{\overline{D}}^{*}$ systems of Prelovsek et al. [Phys. Rev. Lett. 111, 192001 (2013).] with $m_{\pi }\simeq 280$ and 266 MeV, and $L=24a/32a$ ($a\simeq 0.09\mathrm{fm}$) and $L=16a$ ($a\simeq 0.1239(13)\mathrm{fm}$), respectively. The hidden-charm states with $J^{PC}=0^{++}$, $1^{++}$, and $2^{++}$ quantum numbers are then searched for. For $0^{++}$, the analysis reveals three poles in the $D\overline{D}–D_s{\overline{D}}_s$ coupled-channel amplitude, corresponding to three states. Two of these poles, located near the $D\overline{D}$ and $D_s{\overline{D}}_s$ thresholds, can be interpreted as mostly molecular states. A third pole above the $D_s{\overline{D}}_s$ threshold is originated from the $P$-wave ${\chi }_{c0}(2P)$ charmonium state. The number of poles found in the $D\overline{D}–D_s{\overline{D}}_s$ system is the same as that found in the original lattice analysis though the position of the third pole changes sizeably. In the $1^{++}$ sector, we find two poles in the complex energy plane. The first one is related to the molecular $X(3872)$ state, with a compositeness exceeding 90%, while the second one, stemming from the ${\chi }_{c1}(2P)$ charmonium, appears above the $D{\overline{D}}^{*}$ threshold and it likely corresponds to the recently discovered ${\chi }_{c1}(4010)$ state. In the $2^{++}$ sector, we also report two poles and find that the dressed ${\chi }_{c2}(2P)$ is lighter than the $D^{*}{\overline{D}}^{*}$ molecular state, with the dynamics of the latter closely related to that of the heavy-quark spin-symmetry partner of the $X(3872)$. Our exploratory study of the $1^{++}$ and $2^{++}$ sectors offers valuable insights into their dynamics, but given that the fits that we carry out are underconstrained, more lattice data are required to draw robust conclusions.

We revisit the phenomenological ${}^3{P}_0$ model for the decay of quarkonium $(Q\overline{Q})$ into two open flavor mesons ($\overline{\mathfrak{M}}\mathfrak{M}$). We take the heavy-quark limit and derive a transition rate between $Q\overline{Q}$ and $\overline{\mathfrak{M}}\mathfrak{M}$ to be compared with the one calculated in studies of string breaking using lattice QCD. This comparison allows us to fit the creation amplitude of a light quark-antiquark pair in the ${}^3{P}_0$ model to the string-breaking transition rate in QCD.

The cross section for the associated production of a jet with an electroweak gauge boson ($G=W^{\pm },Z^0,\gamma$) at forward rapidities in $pp$ and $pA$ collisions is derived within the color-dipole $S$-matrix framework. We present the full expressions for the differential cross section of the $qp\to GqX$ process in the transverse momentum space, considering the longitudinal and transverse polarizations of the gauge boson. We demonstrate that the final formulas can be expressed in terms of the unintegrated gluon distribution and reproduce previous results for the associated $\mathrm{jet}+\gamma$ and $\mathrm{jet}+Z^0$ production, derived using other frameworks. Moreover, we derive the back-to-back correlation limit of the spectra and show that it can be expressed in terms of the unpolarized and linearly polarized transverse momentum gluon distributions. Our results improve the description of the inclusive jet plus color neutral particle production at forward rapidities, not far from the proton fragmentation region, in $pp$ or $pA$ collisions, and are the main ingredient to study the impact of nonlinear QCD effects in two-particle correlations.

The electron pseudoscalar-nucleon scalar $\mathcal{T}$, $\mathcal{P}$-odd interaction within the framework of the Standard Model is considered as an exchange mediated by the Higgs boson at the quark-gluon level. $\mathcal{CP}$ violation is introduced through a phase factor in the Cabibbo-Kobayashi-Maskawa matrix, which characterizes the flavor structure of the quark loop. We explicitly demonstrate that the total three-loop contribution vanishes for the Higgs-boson exchange mechanism. A nonzero contribution appears at the four-loop quark-gluon level only with the insertion of an additional gluon line between the quarks. The estimate of the $\mathcal{CP}$-odd electron-nucleon interaction coupling constant after reduction of divergencies of the quark loop integral using the Glashow-Iliopoulos-Maiani (GIM) mechanism yields a value $\sim {10}^{-28}$. The final result, expressed in terms of the equivalent electron electric dipole moment ($e\mathrm{EDM}$), is ${10}^{-48}e\mathrm{cm}$, and its order of magnitude coincides with that of the GIM estimate of the $e\mathrm{EDM}$ at the quark-gluon level. Our parametric estimate of the $e\mathrm{EDM}$ differs from previous studies by a factor that depends on the mass of the $b$ quark.

The axion is one of the important candidates of dark matter. To search the monopole-dipole interaction potential between the polarized electron and the unpolarized nucleon mediated by the axions, a measurement scheme with the milligram-scale torsion pendulum is proposed. The ${\mathrm{SiO}}_2$ block is used as the nonpolarized nucleon source and suspended by a thin silica fiber, which forms a milligram-scale torsion pendulum with a sensitivity of $3.2\times {10}^{-19}\mathrm{Nm}/{\mathrm{Hz}}^{1/2}$ at the natural frequency (0.04 Hz). Two SmCo blocks with opposite spin polarization directions are used as the electron spin sources. The gravitational interactions acted on the nucleon source can be canceled out between them, while the interaction to be measured is summed. The milligram-scale torsion pendulum is controlled by two beams, and its angle is measured by using a laser interferometry with a sensitivity of $1\times {10}^{-8}\mathrm{rad}/{\mathrm{Hz}}^{1/2}$. The thermal noise of torque, the residual gravitational torque, the environmental noises, and other noises are analyzed in turn. When the duration of each measurement is set to three days, the combined noise for the measurement is expected to be less than $4.4\times {10}^{-21}$ Nm. When the interaction path $\lambda$ is $40\mathrm{\mu }\mathrm{m}$, the upper bound of $g_s^N{g}_p^e$ for the interaction potential mediated by the axions is expected to be $5.2\times {10}^{-23}$, which is two order of magnitude better than the strictest restriction so far.

Based on the holographic model, which incorporates the equation of state and baryon number susceptibility for different flavors, we calculate the drag force, jet quenching parameter, and diffusion coefficient of the heavy quark at finite temperature and chemical potential. The holographic results for the diffusion coefficient align with lattice data for $N_f=0$ and $N_f=2+1$, falling within their error margins. The holographic diffusion coefficient for heavy quark in the systems of different flavors is compatible with estimates from A Large Ion Collider Experiment data. The jet quenching parameter in our model demonstrates strong consistency with the estimations obtained from Bayesian analysis of data from both relativistic heavy ion collider and LHC for different flavors. We can confirm the model provides a good description of the transport properties of quark-gluon plasma. The work reinforces the potential of bottom-up holographic model in advancing our understanding of transport properties of hot and dense quark-gluon plasma.

We calculate the holographic central charges for general higher curvature gravity theory dual to eight dimensional conformal field theory (CFT). To do this, we first elaborate the general form of Weyl anomaly in 8D CFT and find 11 nontrivial linearly independent curvature combinations, one of which is Euler density and the rest are Weyl invariants, including 7 nondifferentiated ones and 3 differentiated ones. The Weyl invariants are constructed as invariant polynomials of curvature tensor and covariant derivatives. We denote $W_{(n)}$ as the Weyl invariant that contains a polynormial term with a minimum of $n$ curvature tensors. Interestingly, since there are a total of 12 Weyl invariants in 8D, our finding means two of them are trivial and expressible as total derivatives. The resulting central charges are expressed in terms of 15 theory-dependent constants. Remarkably, we find that the $W_{(2)}$ invariant corresponds to the $c$-charge that is proportional to $C_T$, while the two $W_{(3)}$’s are related to three-point function parameters of energy-momentum tensor. This suggests a possible connection between the $c$-charges of $W_{(n)}$’s and the $n$-point functions of energy-momentum tensor.

We study perturbative Wilsonian renormalization group (RG) for the scalar ${\varphi }^4$ theory at finite temperature to one loop order in the Schwinger-Keldysh closed-time-path (CTP) formalism. By explicitly integrating out the UV modes, we show how effective interactions coupling the two branches of the CTP contour arise. This provides a microscopic derivation of the type of effective CTP actions used in the literature. While the full effective theory has no critical points, we instead proceed to study critical properties of the RG flow in a reduced space of complex couplings that characterize certain time-ordered correlators and show the existence of two novel fixed points in $d=4$ spacetime dimensions. We relate one to the Wilson-Fisher fixed point known to exist only in $4-\epsilon$ dimensions, and the other to the standard Gaussian fixed point.

In this paper, we generalize the deformations driven by the stress-energy tensor $T$ and investigate their relation to the flow equation for the background metric at the classical level. For a deformation operator $\mathcal{O}$ as a polynomial function of the stress-energy tensor, we develop a formalism that relates a deformed action to a flow equation for the metric in arbitrary spacetime dimensions. It is shown that in the $T\overline{T}$ deformation and the $\mathcal{O}(T)=\mathrm{tr}[\mathbf{T}{]}^m$ deformation, the flow equations for the metric allow us to directly obtain exact solutions in closed forms. We also demonstrate the perturbative approach to find the same results. As several applications of the $\mathcal{O}(T)=\mathrm{tr}[\mathbf{T}{]}^m$ deformation, we discuss the relation between the deformations and gravitational models. Besides, we also deform the Lagrangians for scalar field theories.

We show that the long-standing problem of gauge dependence of the effective potential arises due to the factorization of the determinant of operators, which is invalid when we take the zeta-regularized trace of the operators. We show by correcting for this assumption by computing the multiplicative anomaly, the gauge-dependent terms of the effective potential cancel. We also show that in two- and odd-dimensional noncompact spacetime manifolds where the multiplicative anomaly term is zero, the standard calculation of one-loop effective potential gives a gauge-independent result. These results are in support of our claim that the multiplicative anomaly may play a crucial role in removing the gauge dependence in the effective potential in the four-dimensional noncompact manifold. Noting the nontrivial aspects of this anomaly computation for a generic scenario, we propose the heat-kernel method to compute the effective potential where this anomaly emerges as a total derivative, thus redundant. We explicitly show how one can calculate the gauge independent, effective action and the Coleman-Weinberg effective potential by employing the heat-kernel method. Based on this result, we advocate the heat-kernel expansion as the most straightforward method, as it naturally deals with the matrix elliptic operator for the calculation of manifestly gauge independent, effective actions compared to other conventional methods.

The vacuum polarization energy is the leading quantum correction to the classical energy of a soliton. We study this energy for two-component solitons in one space dimension as a function of the soliton’s topological charge. We find that both the classical and the vacuum polarization energies are linear functions of the topological charge with a small offset. Because the combination of the classical and quantum offsets determines the binding energies, either all higher charge solitons are energetically bound or they are all unbound, depending on model parameters. This linearity persists even when the field configurations are very different from those of isolated solitons and would not be apparent from an analysis of their bound state spectra alone.

Combining asymptotically safe quantum gravity with a tensor field theory, we exhibit the first example of a theory with gravity and scalar fields in four dimensions which may realize asymptotic safety at a nonvanishing value of the scalar quartic coupling. We first present (further) evidence that in the asymptotic-safety paradigm, quantum fluctuations of gravity generically screen the quartic couplings in (multi)scalar models. For a tensor field theory in which the scalar field transforms under an internal $O(N{)}^3$ symmetry, this has the effect of replacing asymptotic freedom, recently discovered at large $N$ on a fixed flat background, by an interacting fixed point in the presence of quantum gravity. The fixed point originates from the competition between the effects of the matter self-interactions which, contrary to the usual scalar models, are antiscreening, and the screening gravitational effects.

Tidal effects on compact objects provide profound theoretical insights into the structure of the field equations, and are wonderful probes of the equation of state of matter, of the nature of black holes, and of the underlying theory of gravity. The natural framework for understanding tides is a perturbative scheme. Here, we point out ambiguities in determining tidal response functions within such a framework, which may lead to bias in constraining physical parameters with gravitational-wave observations if the computed quantities are not properly linked to observables. We propose a canonical tidal response function definition to compare values of tides in theories beyond vacuum general relativity in a unified manner. As an example, we provide black hole tidal response functions, including both conservative and dissipative pieces, in various theories of gravity. Tidal dissipation Love numbers for black holes are derived here for the first time in most of the non-Einsteinian theories considered in this paper.

The response of astrophysical compact objects to external tidal fields carries valuable information on the nature of these objects, on the equation of state of matter, and on the underlying gravitational theory. In this work, we highlight subtleties in describing relativistic dynamical tidal responses that arise from ambiguities in the decomposition of a perturbed metric into external tidal and induced response pieces. Observables are unambiguous. However, in practice, differences arising from implicit assumptions in the definition of tidal deformabilities may lead to a bias in constraining nuclear physics or gravitational theories, if not properly tied to observational data. We propose calibration of a tidal response function for any compact objects in vacuum general relativity. Within this framework, the dynamical tidal Love numbers of a Schwarzschild black hole (BH) in both even and odd sectors vanish at any multipole order. The calibration allows one to define dynamical tidal deformabilities of relativistic stars, such as neutron stars, as the difference from the BH values (zero) under the unified definition in a simple manner. As a straightforward extension of our framework, we compute the next-to-leading dissipative tidal response of Schwarzschild black holes for the first time to our knowledge.

We investigate gravitational lensing near a charged black hole with a global monopole in the strong field regime, focusing on the combined effects of the global monopole and black hole charge on key observables in gravitational lensing both analytically and numerically. Our results reveal that the dependence of the angular separation on charge is intricately tied to the deficit angle caused by the global monopole. In particular, we identify three critical values of the global monopole parameter that determine whether the angular separation increases monotonically, decreases monotonically, or exhibits extrema as the charge varies. A similar complex dependence is found for the flux ratio as a function of the deficit angle, and for the magnification of the first relativistic image as a function of charge. These behaviors contrast sharply with the monotonic changes observed in the absence of either a global monopole or charge. Our findings highlight that the effects of the charge and global monopole on gravitational lensing cannot be described as simple additive contributions. Instead, their combined effects lead to a rich and interdependent behavior that enhances our understanding of strong-field gravitational lensing. While the charge and global monopole are expected to be small in typical astrophysical contexts, the results presented here could be experimentally explored in analog gravity systems, where these parameters are not constrained. This opens the door to potential experimental verification of the phenomena predicted in this study.

With the increasing use of machine learning (ML) algorithms in scientific research comes the need for reliable uncertainty quantification. When taking a measurement it is not enough to provide the result, we also have to declare how confident we are in the measurement. This is also true when the results are obtained from a ML algorithm, and arguably more so since the internal workings of ML algorithms are often less transparent compared to traditional statistical methods. Additionally, many ML algorithms do not provide uncertainty estimates, and auxiliary algorithms must be applied. Conformal prediction ($CP$) is a framework to provide such uncertainty quantifications for ML point predictors. In this paper, we explore the use and properties of $CP$ applied in the context of glitch classification in gravitational wave astronomy. Specifically, we demonstrate the application of $CP$ to the Gravity Spy glitch classification algorithm. $CP$ makes use of a score function, a nonconformity measure, to convert an algorithm’s heuristic notion of uncertainty to a rigorous uncertainty. We use the application on Gravity Spy to explore the performance of different nonconformity measures and optimize them for our application. Our results show that the optimal nonconformity measure depends on the specific application, as well as the metric used to quantify the performance.

We performed a series of 769 full numerical simulations of the high-energy collision of black holes to search for the maximum gravitational energy $E_{\mathrm{rad}}$ emitted during their merger. We consider equal-mass binaries with spins pointing along their orbital angular momentum $\overrightarrow{L}$ and perform a search over impact parameters $b$ and initial linear momenta $p/m=\gamma v$ to find the maximum $E_{\mathrm{rad}}$ for a given spin $\overrightarrow{S}$. The total radiated energy proves to have a weak dependence on the intrinsic spin $s$ of the holes, for the sequence $s=+0.8,0.0,-0.8$ studied here. We thus estimate the maximum, $E_{\mathrm{rad}}^{\max }/M_{\mathrm{ADM}}\approx 32\%\pm 2\%$, for these direct merger encounters. We also explore the radiated angular momentum and the maximum spin of the merger remnant (within these configurations), finding ${\alpha }_f^{\max }=0.987$. We then use the zero-frequency-limit expansion to analytically model the radiated energy in the small-impact-parameter and large-initial-linear-momentum regime.