A measurement is presented of the production of $Z$ bosons that decay into two electrons or muons in association with jets, in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were recorded by the CMS Collaboration at the LHC with an integrated luminosity of $35.9{\mathrm{fb}}^{-1}$. The differential cross sections are measured as a function of the transverse momentum ($p_{\mathrm{T}}$) of the $Z$ boson and the transverse momentum and rapidities of the five jets with largest $p_{\mathrm{T}}$. The jet multiplicity distribution is measured for up to eight jets. The hadronic activity in the events is estimated using the scalar sum of the $p_{\mathrm{T}}$ of all the jets. All measurements are unfolded to the stable-particle level and compared with predictions from various Monte Carlo event generators, as well as with expectations at leading and next-to-leading orders in perturbative quantum chromodynamics.

We propose a setting that simulates Hawking radiation from an analogue bouncing geometry, i.e., a collapsing geometry that reverts its collapse after a finite time, in a setup consisting of a coplanar waveguide terminated in superconducting quantum-interference devices at both ends. We demonstrate experimental feasibility of the proposed setup within the current technology. Our analysis illustrates the resilience of Hawking radiation under changes in the physics at energy scales much larger than the temperature, supporting the idea that regular alternatives to black holes would also emit Hawking radiation.

Precision measurements of the possible coupling of spin to other (pseudo)scalar and (pseudo)vector fields has proven to be a sensitive way to search for new particle physics beyond the standard model. Indeed, in addition to searching for exotic spin-spin interactions, studies have been undertaken to look for couplings of spin to gravity, the relative velocity between particles, and preferred directions. Several laboratory experiments have established upper bounds on the energy associated with various fermion spin-orientations relative to Earth. Here, we combine these results with a model of Earth as a moving unpolarized source in order to investigate the possible long-range spin-velocity interactions associated with the exchange of ultralight ($m_{z^{\prime }}<1\mathrm{neV}$) or massless scalar or vector bosons. We establish stringent bounds on the strength of these couplings between electrons, neutrons, protons, and nucleons.

The $X(6900)$ resonance, originally discovered by the LHCb Collaboration and later confirmed by both the ATLAS and CMS experiments, has sparked broad interest in the fully charmed tetraquark states. Relative to the mass spectra and decay properties of fully heavy tetraquarks, our knowledge on their production mechanism is still rather limited. In this work, we investigate the inclusive production of fully charmed $S$-wave tetraquarks at the LHC within the nonrelativistic QCD factorization framework. The partonic cross sections are computed at lowest order in ${\alpha }_s$ and velocity, while the long-distance nonrelativistic QCD matrix elements are estimated from phenomenological potential models. We predict the differential $p_T$ spectra of various fully charmed $S$-wave tetraquarks at the LHC and compare with the results predicted from the fragmentation mechanism at the large-$p_T$ end.

We study quantum spacetime fluctuations near light-sheet horizons associated with a Rindler wedge in anti–de Sitter (AdS) spacetime, in the context of $\mathrm{AdS}/\mathrm{CFT}$. In particular, we solve the vacuum Einstein equation near the light-sheet horizon, augmented with the ansatz of a quantum source smeared out in a Planckian width along one of the light-cone directions. Such a source, whose physical interpretation is of gravitational shock waves created by vacuum energy fluctuations, alters the Einstein equation to a stochastic partial differential equation taking the form of a Langevin equation. By integrating fluctuations along the light sheet, we find an accumulated effect in the round-trip time of a photon to traverse the horizon of the Rindler wedge that depends on both the $d$-dimensional Newton constant $G_N^{(d)}$ and the AdS curvature $L$, in agreement with previous literature utilizing different methods.

The equation of state (EOS) of nuclear dense matter plays a crucial role in many astrophysical phenomena associated with neutron stars (NSs). Fluid oscillations are one of the most fundamental properties therein. NSs support a family of gravity $g$-modes, which are related to buoyancy. We study the gravity $g$-modes caused by composition gradient and density discontinuity in the framework of pseudo-Newtonian gravity. The mode frequencies are calculated in detail and compared with Newtonian and general-relativistic (GR) solutions. We find that the $g$-mode frequencies in one of the pseudo-Newtonian treatments can approximate remarkably well the GR solutions, with relative errors in the order of 1%. Our findings suggest that, with much less computational cost, pseudo-Newtonian gravity can be utilized to accurately analyze oscillation of NSs constructed from an EOS with a first-order phase transition between nuclear and quark matter, as well as to provide an excellent approximation of GR effects in core-collapse supernova (CCSN) simulations.

In this work we establish in a rigorous manner, and a model-independent way, the conditions for bypassing Bekenstein’s no-scalar-hair theorem for static, spherically symmetric, and asymptotically flat black holes, while maintaining the validity of the energy conditions. Specifically, we argue that an assumption in the theorem, namely the vanishing of the quantity $\mathcal{G}=\mathcal{E}+{T^{\theta }}_{\theta }$, where $\mathcal{E}$ is the energy density and ${T^{\theta }}_{\theta }$ the corresponding component of the energy-momentum tensor of the scalar field theory, can be relaxed. Indeed, if $\mathcal{G}$ is positive, as a consequence of the assumption on the validity of the energy conditions, then scalar hair is potentially allowed in the black hole’s exterior, consistently with the gravitational equations and the generic properties of the (nontrivial) energy-momentum tensor. As an explicit example, in which such a behavior is realized, we discuss the well-known model of a ($3+1$)-dimensional Schwarzschild black hole coupled to a spontaneously broken Yang-Mills $SU(2)$ gauge theory interacting with a Higgs scalar. We present a rather novel approach to obtain analytical black-hole solutions for this system (in contrast to the numerical ones in the existing literature) by applying an appropriate perturbative treatment whereby the black-hole configuration is derived as a result of backreaction of Higgs and gauge fields onto an initially fixed flat spacetime. The massive nature of the scalar and gauge fields in this example requires a special treatment because of their asymptotic form, which we discuss in some detail.

Detections of gravitational waves emitted from binary black hole coalescences allow us to probe the strong-field dynamics of general relativity (GR). One can compare the observed gravitational-wave signals with theoretical waveform models to constrain possible deviations from GR. Any physics that is not included in these waveform models might show up as apparent GR deviations. The waveform models used in current tests of GR describe binaries on quasicircular orbits, since most of the binaries detected by ground-based gravitational-wave detectors are expected to have negligible eccentricities. Thus, a signal from an eccentric binary in GR is likely to show up as a deviation from GR in the current implementation of these tests. We study the response of four standard tests of GR to eccentric binary black hole signals with the forecast O4 sensitivity of the LIGO-Virgo network. Specifically, we consider two parametrized tests (TIGER and FTI), the modified dispersion relation test, and the inspiral-merger-ringdown consistency test. To model eccentric signals, we use nonspinning numerical relativity simulations from the SXS catalog with three mass ratios (1, 2, 3), which we scale to a redshifted total mass of $80M_{\odot }$ and luminosity distance of 400 Mpc. For each of these mass ratios, we consider signals with eccentricities of $\sim 0.05$ and $\sim 0.1$ at 17 Hz. We find that signals with larger eccentricity lead to very significant false GR deviations in most tests while signals having smaller eccentricity lead to significant deviations in some tests. For the larger eccentricity cases, one would even get a deviation from GR with TIGER at $\sim 90\%$ credibility at a distance of $\gtrsim 1.5\mathrm{Gpc}$. Thus, it will be necessary to exclude the possibility of an eccentric binary in order to make any claim about detecting a deviation from GR.

We investigate spherical domain walls (DWs) nucleated via quantum tunneling in multifield inflationary models and curvature perturbations induced by the inhomogeneous distribution of those DWs. We consider the case that the Euclidean action $S_E$ of DWs changes with time during inflation so that most DWs nucleate when $S_E$ reaches the minimum value and the radii of DWs are almost the same. When the Hubble horizon scale exceeds the DW radius after inflation, DWs begin to annihilate and release their energy into background radiation. Because of the random nature of the nucleation process, the statistics of DWs is of the Poisson type and the power spectrum of curvature perturbations has a characteristic slope ${\mathcal{P}}_{\mathcal{R}}(k)\propto k^3$. The amplitude of ${\mathcal{P}}_{\mathcal{R}}(k)$ depends on the tension and abundance of DWs at the annihilation time, while the peak mode depends on the mean separation of DWs. We also numerically obtain the energy spectra of scalar-induced gravitational waves from predicted curvature perturbations that are expected to be observed in multiband gravitational-wave detectors.

We examine the gravitational wave frequencies of the fundamental ($f$-) and first pressure ($p_1$-) modes excited in the neutron star models constructed with the quark-hadron crossover (QHC)-type equations of state (EOSs). We find that the $f$-mode frequencies with QHC EOS basically are smaller and the $p_1$-mode frequencies with QHC EOS are larger than those with hadronic EOS, focusing on the neutron star model with a fixed mass. We also find that the universality in the $f$-mode frequencies multiplied by the stellar mass as a function of the stellar compactness or as a function of the dimensionless tidal deformability, which is derived with various hadronic EOSs, can keep even with QHC EOS. That is, using these universal relations, one cannot distinguish QHC EOS from hadronic EOSs. Instead, using the relations one can extract the stellar radii whose evolution from low- to high-mass neutron stars can differentiate QHC from hadronic EOSs. On the other hand, we find that the $p_1$-mode frequencies multiplied by the stellar mass with QHC EOS significantly deviate in a certain mass range from the corresponding empirical relations derived with various hadronic EOSs, with which one may distinguish QHC EOS from hadronic EOSs.

The fast flavor conversions (FFCs) of neutrinos generally exist in core-collapse supernovae and binary neutron-star merger remnants and can significantly change the flavor composition and affect the dynamics and nucleosynthesis processes. Several analytical prescriptions were proposed recently to approximately explain or predict the asymptotic outcome of FFCs for systems with different initial or boundary conditions, with the aim for providing better understandings of FFCs and for practical implementation of FFCs in hydrodynamic modeling. In this work, we obtain the asymptotic survival probability distributions of FFCs in a survey over thousands of randomly sampled initial angular distributions by means of numerical simulations in one-dimensional boxes with the periodic boundary condition. We also propose improved prescriptions that guarantee the continuity of the angular distributions after FFCs. Detailed comparisons and evaluation of all these prescriptions with our numerical survey results are performed. The survey dataset is made publicly available to inspire the exploration and design for more effective methods applicable to realistic hydrodynamic simulations.

PICO bubble chambers have exceptional sensitivity to inelastic dark matter-nucleus interactions due to a combination of their extended nuclear-recoil energy detection window from a few keV to $O(100\mathrm{keV})$ or more and the use of iodine as a heavy target. Inelastic dark matter-nucleus scattering is interesting for studying the properties of dark matter, where many theoretical scenarios have been developed. This study reports the results of a search for dark matter inelastic scattering with the PICO-60 bubble chambers. The analysis reported here comprises physics runs from PICO-60 bubble chambers using ${\mathrm{CF}}_3\mathrm{I}$ and ${\mathrm{C}}_3{\mathrm{F}}_8$. The ${\mathrm{CF}}_3\mathrm{I}$ run consisted of 36.8 kg of ${\mathrm{CF}}_3\mathrm{I}$ reaching an exposure of $3415\mathrm{kg}\text{−}\mathrm{day}$ operating at thermodynamic thresholds between 7 and 20 keV. The ${\mathrm{C}}_3{\mathrm{F}}_8$ runs consisted of 52 kg of ${\mathrm{C}}_3{\mathrm{F}}_8$ reaching exposures of 1404 and $1167\mathrm{kg}\text{−}\mathrm{day}$ running at thermodynamic thresholds of 2.45 and 3.29 keV, respectively. The analysis disfavors various scenarios, in a wide region of parameter space, that provide a feasible explanation of the signal observed by the DAMA experiment, assuming an inelastic interaction, considering that the PICO ${\mathrm{CF}}_3\mathrm{I}$ bubble chamber used iodine as the target material.

We scrutinize the physical viability of the minimal nonsupersymmetric SO(10) grand unified theory with the scalar sector $\mathbf{45}\oplus \mathbf{126}\oplus {\mathbf{10}}_{\mathbb{C}}$, in which the unified symmetry is broken by the former two representations, and a realistic Yukawa sector is supported by the last two. Alongside the known issue of a relatively low grand unified theory scale (and thus overly fast proton decay) encountered in minimally fine-tuned scenarios, we identify a very general problem of the model: the inability to properly accommodate a Standard-Model-like low-energy Higgs doublet in the perturbative regime.

We show that three open questions in particle physics and cosmology: the origin of neutrino mass, the identity of dark matter, and the origin of the baryon asymmetry of the universe can be explained simultaneously in the three-loop seesaw model proposed by Krauss, Nasri, and Trodden. We discuss the difficulty of successful leptogenesis with three right-handed neutrinos, and we propose a scenario with four right-handed neutrinos that satisfies all observational constraints. This scenario predicts a sleptonlike particle as light as a few hundreds GeV that can be probed by future collider experiments.

In this work we study charmonium production in high multiplicity proton-proton collisions. We investigate the role of the spatial distribution of partons in the protons and assume that the proton has a Y shape. In this configuration quarks are more at the surface and gluons in the inner part of the proton. Going from peripheral to more central and then to ultracentral proton-proton collisions, we move from quark-quark collisions to gluon-gluon collisions. Since gluons are much more abundant, the cross sections grow. In the case of charm production this growth is enhanced by the fact that $\sigma (g+g\to c+\overline{c})\gg \sigma (q+\overline{q}\to c+\overline{c})$. These effects can explain the growth seen in the data.

Mass spectra and Mott transitions of pions $({\pi }^0,{\pi }^{\pm })$ at finite temperature and magnetic field are investigated in a two-flavor Nambu–Jona-Lasinio model, and we focus on the inverse magnetic catalysis (IMC) effect and current quark mass (CQM) effect. Due to the dimension reduction of the constituent quarks, the pion masses jump at their Mott transitions, which is independent of the IMC effect and CQM effect. We consider the IMC effect by using a magnetic-field-dependent coupling constant, which is a monotonic decreasing function of magnetic field. With the IMC effect, the Mott transition temperature of ${\pi }^0$ mesons, $T_m^0$, is a monotonic decreasing function of magnetic field. For charged pions, ${\pi }^{\pm }$, the Mott transition temperature $T_m^{+}$ increases quickly in the weak magnetic field region and then decreases with increasing magnetic field, which is accompanied with some oscillations. Comparing with the case without IMC, $T_m^0$ and $T_m^{+}$ are lower when including the IMC effect. The CQM effect is considered by varying parameter $m_0$ in the nonchiral limit. For ${\pi }^0$ mesons, $T_m^0$ is not a monotonic function of magnetic field with low $m_0$, but it is a monotonic decreasing function with larger $m_0$. In the weak magnetic field region, $T_m^0$ is higher for larger $m_0$, but in the strong magnetic field region, it is lower for larger $m_0$. For ${\pi }^{+}$ mesons, $T_m^{+}$ is only quantitatively modified by the current quark mass effect, and it becomes higher with larger $m_0$.

The determination of the $Zb\overline{b}$ coupling in experiments has been a longstanding challenge, as the limited precision of off $Z$-pole measurements at the LEP has resulted in two degenerate solutions remained to be resolved. In this paper, we propose a novel method to probe the $Zb\overline{b}$ coupling by measuring the forward-backward asymmetry of the bottom quark, $A_{\mathrm{FB}}^b$, in the $b\overline{b}$ system of the $e^{+}{e}^{-}\to b\overline{b}\gamma$ and/or $e^{+}{e}^{-}\to b\overline{b}g$ processes at the $Z$-pole of future lepton colliders. The additional hard photon or light jet radiation can mimic the energy scanning of the $e^{+}{e}^{-}\to b\overline{b}$ process, and the $A_{\mathrm{FB}}^b$ distribution from the $\gamma \text{−}Z$ interference process is linearly sensitive to the $Zb\overline{b}$ coupling. By combining the expected measurements of $R_b^0$ and $A_{\mathrm{FB}}^{0,b}$ at the $Z$-pole at the CEPC, the $A_{\mathrm{FB}}^b$ distributions can break the degeneracy observed at the LEP, leading to a unique determination of the $Zb\overline{b}$ coupling through $Z$-pole running alone.

A search for nonresonant Higgs boson pair production in the $b\overline{b}b\overline{b}$ final state is presented. The analysis uses $126{\mathrm{fb}}^{-1}$ of $pp$ collision data at $\sqrt{s}=13\mathrm{TeV}$ collected with the ATLAS detector at the Large Hadron Collider, and targets both the gluon-gluon fusion and vector-boson fusion production modes. No evidence of the signal is found and the observed (expected) upper limit on the cross section for nonresonant Higgs boson pair production is determined to be 5.4 (8.1) times the Standard Model predicted cross section at 95% confidence level. Constraints are placed on modifiers to the $HHH$ and $HHVV$ couplings. The observed (expected) $2\sigma$ constraints on the $HHH$ coupling modifier, ${\kappa }_{\lambda }$, are determined to be $[-3.5,11.3]$ ($[-5.4,11.4]$), while the corresponding constraints for the $HHVV$ coupling modifier, ${\kappa }_{2V}$, are $[-0.0,2.1]$ ($[-0.1,2.1]$). In addition, constraints on relevant coefficients are derived in the context of the Standard Model effective field theory and Higgs effective field theory, and upper limits on the $HH$ production cross section are placed in seven Higgs effective field theory benchmark scenarios.

A novel technique based on machine learning is introduced to reconstruct the decays of highly Lorentz-boosted particles. Using an end-to-end deep learning strategy, the technique bypasses existing rule-based particle reconstruction methods typically used in high energy physics analyses. It uses minimally processed detector data as input and directly outputs particle properties of interest. The new technique is demonstrated for the reconstruction of the invariant mass of particles decaying in the CMS detector. The decay of a hypothetical scalar particle $\mathcal{A}$ into two photons, $\mathcal{A}\to \gamma \gamma$, is chosen as a benchmark decay. Lorentz boosts ${\gamma }_{\mathrm{L}}=60–600$ are considered, ranging from regimes where both photons are resolved to those where the photons are closely merged as one object. A training method using domain continuation is introduced, enabling the invariant mass reconstruction of unresolved photon pairs in a novel way. The new technique is validated using ${\pi }^0\to \gamma \gamma$ decays in LHC collision data.

Based on $(448.1\pm 2.9)\times {10}^6$ $\psi (3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decay $\psi (3686)\to \varphi K_S^0{K}_S^0$ is observed for the first time. Taking the interference between $\psi (3686)$ decay and continuum production into account, the branching fraction of this decay is measured to be $\mathcal{B}(\psi (3686)\to \varphi K_S^0{K}_S^0)=(3.53\pm 0.20\pm 0.21)\times {10}^{-5}$, where the first uncertainty is statistical and the second is systematic. Combining with the world average value for $\mathcal{B}(J/\psi \to \varphi K_S^0{K}_S^0)$, the ratio $\mathcal{B}(\psi (3686)\to \varphi K_S^0{K}_S^0)/\mathcal{B}(J/\psi \to \varphi K_S^0{K}_S^0)$ is determined to be $(6.0\pm 1.6)\%$, which is suppressed relative to the 12% rule.