We discuss axionlike particles (ALPs) within the framework of Higgs effective field theory, targeting instances of close alignment of ALP physics with a custodial singlet character of the Higgs boson. We tension constraints arising from new contributions to Higgs boson decays against limits from high-momentum transfer processes that become under increasing control at the LHC. Going beyond leading-order approximations, we highlight the importance of multitop and multi-Higgs production for the pursuit of searches for physics beyond the Standard Model extensions.

Symplectic gauge theories coupled to matter fields lead to symmetry enhancement phenomena that have potential applications in such diverse contexts as composite Higgs, top partial compositeness, strongly interacting dark matter, and dilaton-Higgs models. These theories are also interesting on theoretical grounds, for example in reference to the approach to the large-$N$ limit. A particularly compelling research aim is the determination of the extent of the conformal window in gauge theories with symplectic groups coupled to matter, for different groups and for field content consisting of fermions transforming in different representations. Such determination would have far-reaching implications, but requires overcoming huge technical challenges. Numerical studies based on lattice field theory can provide the quantitative information necessary to this endeavor. We developed new software to implement symplectic groups in the Monte Carlo algorithms within the Grid framework. In this paper, we focus most of our attention on the $Sp(4)$ lattice gauge theory coupled to four (Wilson-Dirac) fermions transforming in the 2-index antisymmetric representation, as a case study. We discuss an extensive catalog of technical tests of the algorithms and present preliminary measurements to set the stage for future large-scale numerical investigations. We also include the scan of parameter space of all asymptotically free $Sp(4)$ lattice gauge theories coupled to varying number of fermions transforming in the antisymmetric representation.

Analytical formulas describing the correction due to the $Z$ boson exchange to the cross section of the reaction $pp\to p{\mu }^{+}{\mu }^{-}X$ are presented. When the invariant mass of the produced muon pair $W\gtrsim 150\mathrm{GeV}$ and its total transverse momentum is large, the correction is of the order of 20%.

In this work, we study the flavor-changing neutral-current process $B_c\to D_s^{*}(\to D_s\pi ){\ell }^{+}{\ell }^{-}$ ($\ell =e$, $\mu$, $\tau$). The relevant weak transition form factors are obtained by using the covariant light-front quark model, in which the main inputs, i.e., the meson wave functions of $B_c$ and $D_s^{*}$, are adopted as the numerical wave functions from the solution of the Schrödinger equation with the modified Godfrey-Isgur model. With the obtained form factors, we further investigate the relevant branching fractions and their ratios, and some angular observables, i.e., the forward-backward asymmetry $A_{\mathrm{FB}}$, the polarization fractions $F_{L(T)}$, and the $CP$-averaged angular coefficients $S_i$ and the $CP$ asymmetry coefficients $A_i$. We also present our results of the clean angular observables $P_{1,2,3}$ and $P_{4,5,6,8}^{\prime }$, which can reduce the uncertainties from the form factors. Our results show that the corresponding branching fractions of the electron or muon channels can reach up to ${10}^{-8}$. With more data being accumulated in the LHCb experiment, our results are helpful for exploring this process, and deepen our understanding of the physics around the $b\to s{\ell }^{+}{\ell }^{-}$ process.

We report an updated measurement of the ${\nu }_{\mu }$-induced, and the first measurement of the ${\overline{\nu }}_{\mu }$-induced coherent charged pion production cross section on ${}^{12}\mathrm{C}$ nuclei in the Tokai-to-Kamioka experiment. This is measured in a restricted region of the final-state phase space for which $p_{\mu ,\pi }>0.2\mathrm{GeV}$, $\cos ({\theta }_{\mu })>0.8$ and $\cos ({\theta }_{\pi })>0.6$, and at a mean (anti)neutrino energy of 0.85 GeV using the T2K near detector. The measured ${\nu }_{\mu }$ charged current coherent pion production flux-averaged cross section on ${}^{12}\mathrm{C}$ is $(2.98\pm 0.37(\mathrm{stat})\pm 0.31(\mathrm{syst}{)}_{-0.00}^{+0.49}({\mathrm{Q}}^2\text{model}))\times {10}^{-40}{\mathrm{cm}}^2$. The new measurement of the ${\overline{\nu }}_{\mu }$-induced cross section on ${}^{12}\mathrm{C}$ is $(3.05\pm 0.71(\mathrm{stat})\pm 0.39(\mathrm{syst}{)}_{-0.00}^{+0.74}({\mathrm{Q}}^2\text{model}))\times {10}^{-40}{\mathrm{cm}}^2$. The results are compatible with both the NEUT 5.4.0 Berger-Sehgal (2009) and GENIE 2.8.0 Rein-Sehgal (2007) model predictions.

For the first time at LHC energies, the forward rapidity gap spectra from proton-lead collisions for both proton and lead dissociation processes are presented. The analysis is performed over 10.4 units of pseudorapidity at a center-of-mass energy per nucleon pair of ${\sqrt{s}}_{\mathrm{NN}}=8.16\mathrm{TeV}$, almost 300 times higher than in previous measurements of diffractive production in proton-nucleus collisions. For lead dissociation processes, which correspond to the pomeron-lead event topology, the epos-lhc generator predictions are a factor of 2 below the data, but the model gives a reasonable description of the rapidity gap spectrum shape. For the pomeron-proton topology, the epos-lhc, qgsjet ii, and hijing predictions are all at least a factor of 5 lower than the data. The latter effect might be explained by a significant contribution of ultraperipheral photoproduction events mimicking the signature of diffractive processes. These data may be of significant help in understanding the high energy limit of quantum chromodynamics and for modeling cosmic ray air showers.

The semiclassical backreaction equations are solved in closed Robertson-Walker spacetimes containing a positive cosmological constant and a conformally coupled massive scalar field. Renormalization of the stress-energy tensor results in higher derivative terms that can lead to solutions that vary on much shorter time scales than the solutions that would occur if the higher derivative terms were not present. These extra solutions can be eliminated through the use of order reduction. Four different methods of order reduction are investigated. These are first applied to the case when only conformally invariant fields, with and without classical radiation, are present. Then they are applied to the massive conformally coupled scalar field. The effects of different adiabatic vacuum states for the massive field are considered. It is found that if enough particles are produced, then the Universe collapses to a final singularity. Otherwise it undergoes a bounce, but at a smaller value of the scale factor (for the models considered) than occurs for the classical de Sitter solution. The stress-energy tensor incorporates both particle production and vacuum polarization effects. An analysis of the energy density of the massive field is done to determine when the contribution from the particles dominates.

We study the conditions under which 4D $\mathcal{N}=2$ superconformal field theories (SCFTs) have multiplets housing operators that are chiral with respect to an $\mathcal{N}=1$ subalgebra. Our main focus is on the set of often-ignored and relatively poorly understood $\overline{\mathcal{B}}$ representations. These multiplets typically evade direct detection by the most popular nonperturbative 4D $\mathcal{N}=2$ tools and correspondences. In spite of this fact, we demonstrate the ubiquity of $\overline{\mathcal{B}}$ multiplets and show that they are associated with interesting phenomena. For example, we give a purely algebraic proof that they are present in all local unitary $\mathcal{N}>2$ SCFTs. We also show that $\overline{\mathcal{B}}$ multiplets exist in $\mathcal{N}=2$ theories with rank greater than one and a conformal manifold or a freely generated Coulomb branch. Using recent topological quantum field theory results, we argue that certain $\overline{\mathcal{B}}$ multiplets exist in broad classes of theories with the ${\mathbb{Z}}_2$-valued ’t Hooft–Witten anomaly for $Sp(N)$ global symmetry. Motivated by these statements, we then study the question of when $\overline{\mathcal{B}}$ multiplets exist in rank-one SCFTs with exactly $\mathcal{N}=2$ supersymmetry and a vanishing ’t Hooft–Witten anomaly. We conclude with various open questions.

Understanding the light ring, one kind of fundamental orbit, shall provide us with novel insight into the astronomical phenomena, such as the ringdown of binary mergers and shadows of black holes. Recently, a topological approach has preliminarily demonstrated its potential advantages on the properties of the light rings. However, extremal spinning black holes remain to be tested. In this paper, we aim to address this issue. Because of the Newman-Unti-Tamburino (NUT) charge, the Kerr-Newman-Taub-NUT solution has no ${\mathbb{Z}}_2$ symmetry. By constructing the corresponding topology for the nonextremal spinning black holes, we find the topological number remains unchanged. This indicates that ${\mathbb{Z}}_2$ symmetry has no influence on the topological number, while it indeed affects the locations of the light rings and deviates them off the equatorial plane. For the extremal spinning black holes, we find its topology is critically dependent on the leading term of the vector’s radial component at the zero point of its angular component on the black hole horizon. The findings state that there exists a topological phase transition, where the topological number changes, for the prograde light rings; while no phase transition occurs for the retrograde light rings. Our study uncovers some universal topological properties for the extremal and nonextremal spinning black holes with or without ${\mathbb{Z}}_2$ symmetry. It also has enlightening significance for understanding the light rings in a more general black hole background.

Gravitational wave echo signals have been proposed as evidence for the modification of the spacetime structure near the classical event horizon. These signals are expected to occur after the mergers of compact binaries as a sequence of weak pulselike signals. Some studies have shown evidence of the echo signals from several binary black hole merger events. On the other hand, the other studies have shown the low significance of such signals from various events in the first, second, and third observing runs (O1, O2, and O3). Our previous study also shows the low significance of echo signals from events in O1 and O2, though, we observe that more than half of the events have p-value smaller than 0.1 when the simply modeled waveform is used for the analysis. Since there are only nine events appropriate for this analysis in O1 and O2, it is necessary to analyze more events to evaluate the significance statistically. In this study, we search for echo signals from binary black hole events observed during O3 operated by LIGO, Virgo, and KAGRA collaborations. We perform the template-based search by using two different models for echo signal templates: simply modeled one and physically motivated one. Our results show that the distributions of p-values for all events analyzed in this study are consistent with the noise distribution. This means that no significant echo signals are found for both models from O3 events.

According to the best-fit parameters of the Standard Model, the Higgs field’s potential reaches a maximum at a field value $h\sim {10}^{10-11}\mathrm{GeV}$ and then turns over to negative values. During reheating after inflation, resonance between the inflaton and the Higgs field can cause the Higgs field to fluctuate past this maximum and run down the dangerous side of the potential if these fields couple too strongly. In this paper, we place constraints on the inflaton Higgs field couplings such that the probability of the Higgs field entering the unstable regime during reheating is small. To do so, the equations of motion are approximately solved semianalytically, then solved fully numerically. Next, the growth in variance is used to determine the parameter space for $\kappa$ and $\alpha$, the coupling coefficients for inflaton Higgs field cubic and quartic interactions, respectively. We find the upper bounds of $\kappa <1.6\times {10}^{-5}{m}_{\varphi }\sim 2.2\times {10}^8\mathrm{GeV}$ and $\alpha <{10}^{-8}$ to allow the Higgs field to remain stable in most Hubble parameter patches during reheating, and we also find the full two parameter joint constraints. We find a corresponding bound on the reheat temperature of $T_{\mathrm{reh}}\lesssim 9.2\times {10}^9\mathrm{GeV}$. Additionally, de Sitter temperature fluctuations during inflation put a lower bound on inflaton Higgs field coupling by providing an effective mass for the Higgs field, pushing back its hilltop during inflation. These additional constraints provide a lower bound on $\alpha$, while $\kappa$ must also be nonzero for the inflaton to decay efficiently.

Quantum decoherence effects in neutrinos, described by the open quantum systems formalism, serve as a gateway to explore potential new physics, including quantum gravity. Previous research extensively investigated these effects across various neutrino sources, imposing stringent constraints on the spontaneous loss of coherence. In this study, we demonstrate that even within the supernovae environment, where neutrinos are released as incoherent states, quantum decoherence could influence the flavor equipartition of $3\nu$ mixing. Additionally, we examine the potential energy dependence of quantum decoherence parameters ($\mathrm{\Gamma }={\mathrm{\Gamma }}_0(E/E_0{)}^n$) with different power laws ($n=0,2,5/2$). Our findings indicate that future-generation detectors (DUNE, Hyper-K, and JUNO) can significantly constrain quantum decoherence effects under different scenarios. For a supernova located 10 kpc away from Earth, if no quantum decoherence is observed, DUNE could potentially establish $3\sigma$ bounds of $\mathrm{\Gamma }\le 6.2\times {10}^{-14}\mathrm{eV}$ in the normal mass hierarchy (NH) scenario, while Hyper-K would impose a $2\sigma$ limit of $\mathrm{\Gamma }\le 3.6\times {10}^{-14}\mathrm{eV}$ for the inverted mass hierarchy (IH) with $n=0$—assuming no energy exchange between the neutrino subsystem and nonstandard environment. These limits become even more restrictive for a closer supernova. When we relax the assumption of energy exchange, for a 10 kpc distance, DUNE could establish a $3\sigma$ limit of ${\mathrm{\Gamma }}_8\le 4.2\times {10}^{-28}\mathrm{eV}$ for NH, while Hyper-K could constrain ${\mathrm{\Gamma }}_8\le 1.3\times {10}^{-27}\mathrm{eV}$ for IH ($n=0$) with $2\sigma$, which would be orders of magnitude stronger than the bounds reported to date. Furthermore, we examine the impact of neutrino loss during propagation for future supernova detection.

Direct detection experiments are still one of the most promising ways to unravel the nature of dark matter. To fully understand how well these experiments constrain the dark matter interactions with the Standard Model particles, all the uncertainties affecting the calculations must be known. It is especially critical now because direct detection experiments recently moved from placing limits only on the two elementary spin independent and spin dependent operators to the complete set of possible operators coupling dark matter and nuclei in nonrelativistic theory. In our work, we estimate the effect of nuclear configuration-interaction uncertainties on the exclusion bounds for one of the existing xenon-based experiments for all fifteen operators. We find that for operator number 13 the $\pm 1\sigma$ uncertainty on the coupling between the dark matter and nucleon can reach more than 50% for dark matter masses between 10 and 1000 GeV. In addition, we discuss how quantum computers can help to reduce this uncertainty and how the uncertainties are affected for couplings obtained for the nonrelativistic reductions of the relativistic interactions.

Oscillons are localized field configurations oscillating in time with lifetimes orders of magnitude longer than their oscillation period. In this paper, we simulate nontraveling oscillons produced by deforming the breather solutions of the sine-Gordon model. Such a deformation treats the dimensionality of the model as a real parameter to produce spherically symmetric oscillons. After considering the post-transient oscillation frequency as a control parameter, we probe the initial parameter space to continuously connect breathers and oscillons at various dimensionalities. For sufficiently small dimensional deformations, we find that oscillons can be treated as perturbatively deformed breathers. In $D\gtrsim 2$ spatial dimensions, we observe solutions undergoing intermittent phases of contraction and expansion in their cores. Knowing that stable and unstable configurations can be mapped to disjoint regions of the breather parameter space, we find that amplitude modulated solutions are located in the middle of both stability regimes. These solutions display the dynamics of critical behavior around the stability limit.

We calculate the two-point massless QCD correlator of nonlocal (composite) vector quark currents with chains of fermion one-loop radiative corrections inserted into gluon lines. The correlator depends on the Bjorken fraction $x$ related to the composite current and, under large-${\beta }_0$ approximation, gives the main contributions in each order of perturbation theory. In the mentioned approximation, these contributions dominate the endpoint behavior of the leading-twist distribution amplitudes of light mesons in the framework of QCD sum rules. Based on this, we analyze the endpoint behavior of these distribution amplitudes for $\pi$ and longitudinally polarized ${\rho }^{\Vert }$ mesons and find inequalities for their moments.

The seesaw extension of the SM explains the tiny neutrino masses, and it is accompanied by many $CP$ violating phases. We study the case where all leptonic $CP$ violation arises from the soft breaking in the heavy Majorana mass matrix. Parameter counting reveals that one less parameter is needed to describe this case. This reduction leads to restrictions on the parameter space of heavy neutrinos. We analyze the minimal seesaw case in detail and find that mass degeneracy of heavy neutrinos is not possible for certain values of the $CP$ phases.

The muonium-to-antimuonium transition experiment is about to be updated. Notably, the experiment at Japan Proton Accelerator Research Complex (J-PARC) can explore the magnetic field dependence of the transition probability. In this paper, we investigate the information that we can extract from the transition probabilities across different magnetic field strengths, while also taking into account a planned transition experiment at China Spallation Neutron Source (CSNS). There are two model-independent parameters in the transition amplitude, and we ascertain the feasibility of determining these parameters, including their relative physical phase, from experimental measurements. This physical phase can be related to the electron electric dipole moment, which is severely constrained by experiments. The underlying mediator responsible for the transition can be either doubly charged particles or neutral particles. In the former case, typical magnetic fields yield specific probability ratios, while the latter presents a range of the probability ratio. We investigate several models with neutral mediators and elucidate that the probability ratio is linked to the sign of new physics contribution to the electron $g-2$. The pivotal role of the J-PARC transition experiment in shedding light on these insights is emphasized.

We studied integration contour deformations in the chiral random matrix theory of Stephanov [Phys. Rev. Lett. 76, 4472 (1996)] with the goal of alleviating the finite-density sign problem. We considered simple ansätze for the deformed integration contours and optimized their parameters. We find that optimization of a single parameter manages to considerably improve on the severity of the sign problem. We show numerical evidence that the improvement achieved is exponential in the degrees of freedom of the system, i.e., the size of the random matrix. We also compare the optimization method with contour deformations coming from the holomorphic flow equations.

We present the first fully differential predictions for tau neutrino scattering in the energy region relevant to the DUNE experiment, including all spin correlations and all tau lepton decay channels. The calculation is performed using a generic interface between the neutrino event generator achilles and the publicly available, general-purpose collider event simulation framework sherpa.