The theory of false vacuum decay in a thermal system may have a crossover from predominantly thermal transitions to quantum transitions as the temperature is decreased. New numerical methods and results are presented here that can be used to model thermal and vacuum bubble nucleation in this regime for cosmology and for laboratory analog of early universe phase transitions.

We propose a variant of electroweak-scale baryogenesis characterized by the spontaneous breaking of the charge-parity ($CP$) symmetry in the early Universe driven by the vacuum expectation value of a $CP$-odd scalar. This $CP$ breaking period in the early Universe would be ended by the electroweak phase transition, with $CP$ being (approximately) conserved at present, thus avoiding the stringent electric dipole moment experimental constraints on beyond-the-Standard-Model sources of $CP$ violation. We study an explicit realization via a nonminimal Higgs sector consisting of two Higgs doublets and a singlet pseudoscalar ($2\mathrm{HDM}+a$). We analyze the region of the $2\mathrm{HDM}+a$ parameter space where such an early Universe period of $CP$ violation occurs, and show that the required thermal history and successful baryogenesis lead to a predictive scenario, testable by a combination of LHC searches and low-energy flavor measurements.

A nonsupersymmetric renormalizable $SO(10)$ model, with $CP$ invariant Yukawa sector consisting of Lorentz scalars in 10 and $\overline{126}$ dimensional representations, is proposed. The elemental Yukawa couplings are real due to $CP$ symmetry. The latter is broken in the low energy effective theory through the standard model Higgs which is a complex linear combination of electroweak doublets residing in 10 and $\overline{126}$ scalars. As a result, the mass matrices in the quark and lepton sectors, including those of heavy and light neutrinos, depend only on three phases which in turn determine $CP$ violation in both sectors. The model is comprehensively analyzed for its viability and predictions including the possibility to generate baryon asymmetry through thermal leptogenesis. It predicts relatively small values for $CP$ phases in the lepton sector. Successful leptogenesis further restricts the ranges to $-0.4\le \sin \delta \le 0.4$ for the Dirac phase and $-0.3\le \sin {\eta }_1\le 0.2$, $-0.5\le \sin {\eta }_2\le 0.5$ for the Majorana phases.

The dynamics of electroweak phase transition could have profound consequences for particle physics and cosmology. We study the prospects for the HL-LHC to probe the strong first-order electroweak phase transition (SFOEWPT) regime in the type-I 2HDM. We focus on the Higgstrahlung channel $pp\to ZH/A$ with a resonant top-quark pair final state $H/A\to t\overline{t}$. We find that the top-quark pair final state renders the largest sensitivity to the SFOEWPT regime, in comparison to the other Higgstrahlung searches already performed by ATLAS and CMS, that focus on the $H/A\to bb$ and $H\to WW$ final states. We also derive the complementarity of the Higgstrahlung searches with other relevant classes of searches at the HL-LHC and compare them with the gravitational wave sensitivity at LISA.

In this paper, we study the capability of different long-baseline experiment options at the KM3NeT facility, i.e., P2O, upgraded P2O, and P2SO to probe the light sterile neutrino and compare their sensitivities with DUNE. The P2O option will have neutrinos from a 90 KW beam at Protvino to be detected at the ORCA detector, the upgraded P2O will have neutrinos from the upgraded 450 KW beam to be detected at the ORCA detector and the option P2SO will have neutrinos from a 450 KW beam to be detected at the upgraded Super-ORCA detector. All these options will have a baseline around 2595 km. Our results show that the experiments at the KM3NeT (DUNE) would be more sensitive if the value of $\mathrm{\Delta }{m}_{41}^2$ is around 10 (1) ${\mathrm{eV}}^2$. Our results also show that the role of near detector is very important for the study of sterile neutrinos and addition of near detector improves the sensitivity as compared to only the far detector for the $3+1$ scenario. Among the three options at KM3NeT, the sensitivity of P2O and upgraded P2O is limited and sensitivity of P2SO is either comparable or better than DUNE.

We present a lattice QCD calculation of the unpolarized isovector quark parton distribution function (PDF) of the proton utilizing a perturbative matching at next-to-next-to-leading-order (NNLO). The calculations are carried out using a single ensemble of gauge configurations generated with $N_f=2+1$ highly-improved staggered quarks with physical masses and a lattice spacing of $a=0.076\mathrm{fm}$. We use one iteration of hypercubic smearing on these gauge configurations, and the resulting smeared configurations are then used for all aspects of the subsequent calculation. For the valence quarks, we use the Wilson-clover action with physical quark masses. We consider several methods for extracting information on the PDF. We first extract the lowest four Mellin moments using the leading-twist operator product expansion approximation. Then, we determine the $x$ dependence of the PDF through a deep neural network within the pseudo-PDF approach and additionally through the framework of large-momentum effective theory utilizing a hybrid renormalization scheme. This is the first application of the NNLO matching coefficients for the nucleon directly at the physical point.

The space-time evolution of the hot and dense fireball of quarks and gluons produced in ultrarelativistic heavy-ion collisions at nonzero baryonic chemical potential and temperature has been studied by using relativistic dissipative hydrodynamics. For this purpose, a numerical code has been developed to solve the relativistic viscous causal hydrodynamics in ($3+1$) dimensions with the inclusion of QCD critical point ($CP$) through the equation of state and scaling behavior of transport coefficients. We compute the transverse momentum spectra, directed and elliptic flow coefficients of pions and protons to comprehend the effect of $CP$ on these observables. It is found that the integration over the entire space-time history of the fireball largely obliterates the effects of $CP$ on the spectra and flow coefficients for the event averaged initial conditions considered here.

The newly observed ${\mathrm{\Omega }}_c(3327)$ gives us a good chance to construct the ${\mathrm{\Omega }}_c$ charmed baryon family. In this work, we carry out the mass spectrum analysis by a nonrelativistic potential model using the Gaussian expansion method, and the study of its two-body Okubo-Zweig-Iizuka–allowed strong decay behavior. Our results imply that the ${\mathrm{\Omega }}_c(3327)$ is a good candidate of the ${\mathrm{\Omega }}_c(1D)$ state with $J^P=5/2^{+}$. We also predict the spectroscopy behavior of other ${\mathrm{\Omega }}_c(1D)$ states, which may provide further clues to their search.

The boost-invariant longitudinal space, defined by the parameter $\sigma =\frac{1}{2}{b}^{-}{P}^{+}$, can be studied from the Fourier transformation of generalized transverse momentum distributions (GTMDs) over the conjugate variable skewness $\xi$. We investigate quark Wigner distributions in the $\sigma$ space in dressed quark model and found diffraction patterns that are analogous to the single slit experiment of light in optics. The width of the central maxima varies with energy transfer to the system and essentially $\xi$ behaves like a slit-width. Qualitatively similar diffraction pattern is reported recently in other models. In this model, we compute all the leading twist GTMDs with nonzero skewness for quarks which provides Wigner distributions under Fourier transformation.

The $f_{\varrho }/m_{\varrho }$ ratio is calculated at ${\mathrm{N}}^3\mathrm{LO}$ order within perturbative (p)non-relativistic quantum chromodynamics (NRQCD) with $N_f$ flavors of mass degenerate fermions. The massless limit of the ratio is expanded á la Banks-Zaks in $ϵ=16.5-N_f$ leading to reliable predictions close to the upper end of the conformal window. The comparison of the next-to-next-to leading order (NNLO) and ${\mathrm{N}}^3\mathrm{LO}$ results indicate that the Banks-Zaks expansion may be reliable down to twelve flavors. Previous lattice calculations combined with the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relations provide us with the same ratio for the range $2\le N_f\le 10$. Assuming a monotonous dependence on $N_f$ leads to an estimate for the lower end of the conformal window, $N_f^{*}\simeq 12$, by matching the nonperturbative and our perturbative results. In any case an abrupt change is observed in $f_{\varrho }/m_{\varrho }$ at twelve flavors. As a cross-check we also consider the $f_{\pi }/m_{\varrho }$ ratio for which lattice results are also available. The perturbative calculation at present is only at the NNLO level which is insufficient for a reliable and robust matching between the low $N_f$ and high $N_f$ regions. Nonetheless, using the relative size of the ${\mathrm{N}}^3\mathrm{LO}$ correction of $f_{\varrho }/m_{\varrho }$ for estimating the same for $f_{\pi }/m_{\varrho }$ leads to the estimate $N_f^{*}\simeq 13$.

The first direct measurement of the absolute branching fraction of ${\mathrm{\Sigma }}^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e$ is reported based on an $e^{+}{e}^{-}$ annihilation sample of $(10087\pm 44)\times {10}^6$ $J/\psi$ events collected with the BESIII detector at $\sqrt{s}=3.097\mathrm{GeV}$. The branching fraction is determined to be $\mathcal{B}({\mathrm{\Sigma }}^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e)=[2.93\pm 0.74(\mathrm{stat})\pm 0.13(\mathrm{syst})]\times {10}^{-5}$, which is the most precise measurement obtained in a single experiment to date and also the first result obtained at a collider experiment. Combining this result with the world average of $\mathcal{B}({\mathrm{\Sigma }}^{-}\to \mathrm{\Lambda }{e}^{-}{\overline{\nu }}_e)$ and the lifetimes of ${\mathrm{\Sigma }}^{\pm }$, the ratio, $\frac{\mathrm{\Gamma }({\mathrm{\Sigma }}^{-}\to \mathrm{\Lambda }{e}^{-}{\overline{\nu }}_e)}{\mathrm{\Gamma }({\mathrm{\Sigma }}^{+}\to \mathrm{\Lambda }{e}^{+}{\nu }_e)}$, is determined to be $1.06\pm 0.28$, which is within 1.8 standard deviations of the value expected in the absence of second-class currents.

We report an extended measurement of the neutron cross section on argon in the energy range of 95–720 MeV. The measurement was obtained with a 4.3-hour exposure of the Mini-CAPTAIN detector to the WNR/LANSCE beam at LANL. Compared to an earlier analysis of the same data, this extended analysis includes a reassessment of systematic uncertainties, in particular related to unused wires in the upstream part of the detector. Using this information we doubled the fiducial volume in the experiment and increased the statistics by a factor of 2.4. We also shifted the analysis from energy bins to time-of-flight bins. This change reduced the overall considered energy range, but improved the understanding of the energy spectrum of incoming neutrons in each bin. Overall, the new measurements are extracted from a fit to the attenuation of the neutron flux in five time-of-flight regions: 140–180 ns, 120–140 ns, 112–120 ns, 104–112 ns, 96–104 ns. The final cross sections are given for the flux-averaged energy in each time-of-flight bin with statistical and systematic (syst) uncertainties: $\sigma (146\mathrm{MeV})=0.60_{-0.14}^{+0.14}\pm 0.08(\mathrm{syst})\mathrm{b}$, $\sigma (236\mathrm{MeV})=0.72_{-0.10}^{+0.10}\pm 0.04(\mathrm{syst})\mathrm{b}$, $\sigma (319\mathrm{MeV})=0.80_{-0.12}^{+0.13}\pm 0.040(\mathrm{syst})\mathrm{b}$, $\sigma (404\mathrm{MeV})=0.74_{-0.09}^{+0.14}\pm 0.04(\mathrm{syst})\mathrm{b}$, $\sigma (543\mathrm{MeV})=0.74_{-0.09}^{+0.09}\pm 0.04(\mathrm{syst})\mathrm{b}$.

The processes $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ and $e^{+}{e}^{-}\to {\mathrm{\Sigma }}^{+}{\overline{\mathrm{\Sigma }}}^{-}$ are studied using initial-state-radiation events in a sample of $980{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The cross sections from the mass threshold to $3\mathrm{GeV}/c^2$ and the effective form factors of ${\mathrm{\Sigma }}^0$ and ${\mathrm{\Sigma }}^{+}$ are measured. In the charmonium region, we observe the decays $J/\psi \to {\mathrm{\Sigma }}^0{\overline{\mathrm{\Sigma }}}^0$ and $J/\psi \to {\mathrm{\Sigma }}^{+}{\overline{\mathrm{\Sigma }}}^{-}$ and determine the respective branching fractions.

A search for dark matter axions with masses $>10\mathrm{\mu }\mathrm{eV}/{\mathrm{c}}^2$ has been performed using the HAYSTAC experiment’s squeezed state receiver to achieve subquantum limited noise. This work includes details of the design and operation of the experiment previously used to search for axions in the mass ranges 16.96–17.12 and $17.14–17.28\mathrm{\mu }\mathrm{eV}/{\mathrm{c}}^2$ (4.100–4.140 GHz and 4.145–4.178 GHz) as well as upgrades to facilitate an extended search at higher masses. These upgrades include improvements to the data acquisition routine which have reduced the effective dead time by a factor of 5, allowing for the new region to be scanned $\sim 1.6$ times faster with comparable sensitivity. No statistically significant evidence of an axion signal is found in the range $18.44–18.71\mathrm{\mu }\mathrm{eV}/{\mathrm{c}}^2$ (4.459–4.523 GHz), leading to an aggregate upper limit exclusion at the 90% level on the axion-photon coupling of $2.06\times g_{\gamma }^{\mathrm{KSVZ}}$.

It was recently understood that if the swampland conjectures are confronted to experiment they naturally point to a solution of the cosmological hierarchy problem in which the smallness of the dark energy is ascribed to an internal (dark) dimension with characteristic length scale in the micron range. It was later inferred that the universal coupling of the Standard Model fields to the massive spin-2 Kaluza-Klein (KK) excitations of the graviton in the dark dimension leads to a dark-matter candidate. Since the partial decay widths of KK gravitons into the visible sector must be relatively small to accommodate experiment, the model is particularly challenging to probe. We show that the model can accommodate neutrino masses associated to right-handed neutrinos propagating in the bulk of the dark dimension with an additional constraint imposed by neutrino oscillation data. After that, we study the impact of the KK tower in cosmology. We show that the modulation of redshifted 21-cm lines driven by $\mathrm{KK}\to \gamma \gamma$ could be within the reach of next generation experiments (e.g., SKA and FARSIDE). We also show that indirect dark-matter searches could uncover the $\mathrm{KK}\to \gamma \gamma$ signal. These two observations combined have the potential for model identification. Finally, we explore the global structure of the inflationary phase and demonstrate that the model parameters required for a successful uniform inflation driven by a five-dimensional cosmological constant (corresponding to a flat region of the five-dimensional potential) are natural.

We study the imprints of a cosmological redshift-dependent pseudoscalar field $\varphi$ on the rotation of cosmic microwave background (CMB) linear polarization generated by a coupling $\varphi F^{\mu \nu }{\tilde{F}}_{\mu \nu }$. We show how either phenomenological or theoretically motivated redshift dependence of the pseudoscalar field, such as those in models of early dark energy, quintessence, or axionlike dark matter, lead to CMB polarization and temperature-polarization power spectra which exhibit a multipole dependence which goes beyond the widely adopted approximation in which the redshift dependence of the linear polarization angle is neglected. Because of this multipole dependence, the isotropic birefringence effect due to a general coupling $\varphi F^{\mu \nu }{\tilde{F}}_{\mu \nu }$ is not degenerate with a systematic calibration angle uncertainty. By taking this multipole dependence into account, we calculate the parameters of these phenomenological and theoretical redshift dependencies of the pseudoscalar field which can be detected by future CMB polarization experiments on the basis of a ${\chi }^2$ analysis for a Wishart likelihood. As a final example of our approach, we compute by Markov chain Monte Carlo the minimal coupling $g_{\varphi }$ in early dark energy which could be detected by future experiments, with or without marginalizing on a systematic rotation angle uncertainty.

The detection of entanglement provides a definitive proof of quantumness. Its ascertainment might be challenging for hot or macroscopic objects, where entanglement is typically weak, but nevertheless present. Here we propose a platform for measuring entanglement by connecting the objects of interest to an uncontrolled quantum network, whose emission (readout) is processed to recognize the state of the former, and hence also the amount of entanglement. First, we demonstrate the platform and its features with generic quantum systems. As the network effectively learns to recognize quantum states, it is possible to sense the amount of entanglement after training with only nonentangled states. Furthermore, by taking into account measurement errors, we demonstrate entanglement sensing with precision that scales beyond the standard quantum limit and outperforms measurements performed directly on the objects. Finally, we utilize our platform for sensing gravity-induced entanglement between two masses and predict an improvement of two orders of magnitude in the precision of entanglement estimation compared to existing techniques.

There are not many tools to quantitatively monitor the emergence of classical geometric features from a quantum spacetime, whose microscopic structure may be a highly quantum-fluctuating “spacetime foam”. To improve this situation, we introduce new quantum observables that allow us to measure the absolute and relative homogeneity of geometric properties of a nonperturbative quantum universe, as function of a chosen averaging scale. This opens a new way to compare results obtained in full quantum gravity to descriptions of the early Universe that assume homogeneity and isotropy at the outset. Our construction is purely geometric and does not depend on a background metric. We illustrate the viability of the quantum homogeneity measures by a nontrivial application to two-dimensional Lorentzian quantum gravity formulated in terms of a path integral over causal dynamical triangulations, and find some evidence of quantum inhomogeneity.

We calculate in a general background gauge, to one-loop order, the leading logarithmic contribution from the graviton self-energy at finite temperature $T$, extending a previous analysis done at $T=0$. The result, which has a transverse structure, is applied to evaluate the leading quantum correction of the gravitational vacuum polarization to the Newtonian potential. An analytic expression valid at all temperatures is obtained, which generalizes the result obtained earlier at $T=0$. One finds that the magnitude of this quantum correction decreases as the temperature rises.