In this paper we use ${\alpha }^{\prime 2}$ corrections to the $D_3$-brane action to obtain a nonzero and positive cosmological constant in the induced cosmology living on the dark bubble. Its measured value together with the value of the fine structure constant correspond to a dark dimension of size $5\times {10}^{-5}\mathrm{m}$ and a string scale at 11 TeV. We conclude that the dark bubble model predicts deviations of Newtonian gravity and stringy excitations of known particles within reach of future experiments.

We used the Cartan formalism to construct fermionic models that are compatible with Galilean or Carrollian symmetry and rigid scaling symmetry. The free Carrollian fermion model exhibits conformal Carrollian symmetry which is isomorphic to the asymptotic symmetries for flat spacetime in three dimensions, namely the ${\mathrm{BMS}}_3$ symmetry. We performed canonical quantization to this free Bondi-van der Burg-Metzner-Sachs (BMS) fermion model, discussed both the highest weight vacuum and the induced vacuum, calculated the correlation functions and the torus partition function. Finally, we constructed $\mathcal{N}=2$ supersymmetric theories by combining the free fermion model and the free scalar model [Phys. Rev. D 105, 125005 (2022)].

Recently, a covariant spherically symmetric model of a black hole within the framework of loop quantum gravity (LQG), characterized by a quantum parameter $r_0$ or $\lambda$, has been proposed. To derive constraints on the LQG-corrected parameter, we explore observational constraints imposed on $r_0$ and $\lambda$ through investigations of the light deflection, the Shapiro time delay, the precession of perihelia, and the geodetic precession test. Among these constraints, the tightest one arises from the Shapiro time delay measured by the Cassini mission, yielding an upper constraint of approximately ${10}^{-5}$.

Various theoretical models predict the existence of exotic compact objects that can mimic the properties of black holes (BHs). Gravitational waves (GWs) from the mergers of compact objects have the potential to distinguish between exotic compact objects and BHs. The measurement of spin-induced multipole moments of compact objects in binaries provides a unique way to test the nature of compact objects. The observations of GWs by LIGO and Virgo have already put constraints on the spin-induced quadrupole moment, the leading order spin-induced moment. In this work, we develop a Bayesian framework to measure the spin-induced octupole moment, the next-to-leading order spin-induced moment. The precise measurement of the spin-induced octupole moment will allow us to test its consistency with that of Kerr BHs in GR and constrain the allowed parameter space for non-BH compact objects. For various simulated compact object binaries, we explore the ability of the LIGO and Virgo detector network to constrain the spin-induced octupole moment. We find that LIGO and Virgo at design sensitivity can constrain the symmetric combination of component spin-induced octupole moments of binary for dimensionless spin magnitudes $\sim 0.8$. Further, we study the possibility of simultaneously measuring the spin-induced quadrupole and octupole moments. Finally, we perform this test on selected GW events reported in the third GW catalog. These are the first constraints on spin-induced octupole moment using full Bayesian analysis.

In this work, we investigate the dynamics of bulk viscous models with decaying vacuum energy density (VED) in a spatially homogeneous and isotropic flat Friedmann-Lemaître-Robertson-Walker spacetime. We particularly are interested to study the viscous models which consider first-order deviation from equilibrium, i.e., the Eckart theory. In the first part, using the most general form of bulk viscous coefficient, we find the analytical solutions of main cosmological parameters, like Hubble parameter, scale factor, matter density, deceleration parameter, and equation of state parameter, and discuss the evolutions of the models accordingly. We also discuss the cosmological consequences of the evolutions and dynamics of three particular viscous models with decaying VED depending on the choices of bulk viscous coefficient. We examine the linear perturbation growth of the model to see if it survives this further level of scrutiny. The second part of the work is devoted to constrain one of the viscous models, viz., $\zeta \propto H$, where $\zeta$ is the bulk viscous coefficient and $H$ is the Hubble parameter, using three different combinations of data from type Ia supernovae (Pantheon), $H(z)$ (cosmic chronometers), baryon acoustic oscillation, and $f(z){\sigma }_8(z)$ measurements with the Markov chain Monte Carlo method. We show that the considered model is compatible with the cosmological probes and the $\mathrm{\Lambda }\mathrm{CDM}$ recovered in late time of the evolution of the Universe. Finally, we obtain selection information criteria (Akaike information criteria and Bayesian information criteria) to study the stability of the models.

We derive an effective field theory (EFT) for cosmological Lyman alpha forest fluctuations valid for the power spectrum at the one-loop order. The “bottom-up” EFT expansion at the level of the transmitted flux is identical to the line-of-sight dependent bias model first derived by Desjacques et al. We confirm this result by a “top-down” derivation based on the exponential map of the optical depth field. Specifically, we show that the combination of the exponential map and conditions of renormalizability generates the same EFT expansion as the “bottom-up” approach. In passing, we point out inconsistencies of the tree-level perturbative expansion of the exponential map without counterterms. To facilitate practical applications, we generalize the FFTLog method for efficient calculations of one-loop integrals from new line-of-sight dependent operators. Finally, we compare the one-loop EFT model against data from the Sherwood hydrodynamic simulation. The theory fits the data with subpercent accuracy up to $k=3h{\mathrm{Mpc}}^{-1}$ at $z=2.8$ for both 3D and 1D correlations. Our model can be readily used for cosmological full-shape analyses of Lyman alpha forest data.

Ultralight bosons are a class of hypothetical particles that could potentially solve critical problems in fields ranging from cosmology to astrophysics and fundamental physics. If ultralight bosons exist, they form clouds around spinning black holes with sizes comparable to their particle Compton wavelength through superradiance. This well-understood classical wave amplification process has been studied for decades. After these clouds form, they dissipate and emit continuous gravitational waves through the annihilation of ultralight bosons into gravitons. These gravitons could be detected with ground-based gravitational-wave detectors using continuous-wave searches. However, it is conceivable for other continuous-wave sources to mimic the emission from the clouds, which could lead to false detections. Here, we investigate how to use continuous waves from clouds formed around known merger remnants to alleviate this problem. In particular, we simulate a catalog of merger remnants that form clouds around them and demonstrate with select “golden” merger remnants how one can perform a Bayesian cross-verification of the ultralight boson hypothesis that has the potential to rule out alternative explanations. Our proof-of-concept study suggests that, in the future, there is a possibility that a merger remnant exists close enough for us to perform the analysis and test the boson hypothesis if the bosons exist in the relevant mass range. Future research will focus on building more sophisticated continuous-wave tools to perform this analysis in practice.

Axion stars could form binaries with neutron stars. Given the extremely strong external magnetic field exhibited by individual neutron stars, there can be a substantial conversion of axions to photons in these binaries. The photon emission is doubly modulated due to the neutron star spinning and the axion star orbiting, yielding a unique discovery signal. Similar features are also generated in binaries between a neutron star and an axion-clouded black hole. Encouragingly, such binaries are found to be within the reach of ongoing and upcoming experiments (e.g., the Five-hundred-meter Aperture Spherical Telescope and the future Square Kilometer Array) for certain parameter regions. They thus provide a promising astronomical laboratory for detecting axions and axion dark matter.

Vortex $\gamma$ photons with intrinsic orbital angular momenta possess a wealth of applications in various fields—e.g., strong-laser physics, nuclear physics, particle physics, and astrophysics—yet their generation remains unsettled. In this work, we investigate the generation of vortex $\gamma$ photons via nonlinear Compton scattering of ultrarelativistic electrons in a circularly polarized laser pulse. We develop a quantum electrodynamics scattering theory that explicitly addresses the multiphoton absorption and the angular momentum transfer mechanism. In pulsed laser fields, we unveil the vortex phase structure of the scattering matrix element, discuss how the vortex phase could be transferred to the radiated photon, and derive the radiation rate of the vortex $\gamma$ photon. We numerically examine the energy spectra and beam characteristics of the radiation, while also investigating the influence of finite laser pulses on the angular momentum and energy distribution of the emitted vortex $\gamma$ photons.

We present results for the isovector axial vector form factors obtained using thirteen $2+1+1$-flavor highly improved staggered quark (HISQ) ensembles generated by the MILC collaboration. The calculation of nucleon two- and three-point correlation functions has been done using Wilson-clover fermions. In the analysis of these data, we quantify the sensitivity of the results to strategies used for removing excited state contamination and invoke the partially conserved axial current relation between the form factors to choose between them. Our data driven analysis includes removing contributions from multihadron $N\pi$ states that make significant contributions. Our final results are $g_A=1.292(53{)}_{\mathrm{stat}}(24{)}_{\mathrm{sys}}$ for the axial charge; $g_S=1.085(50{)}_{\mathrm{stat}}(103{)}_{\mathrm{sys}}$ and $g_T=0.991(21{)}_{\mathrm{stat}}(10{)}_{\mathrm{sys}}$ for the scalar and tensor charges; $⟨r_A^2⟩=0.439(56{)}_{\mathrm{stat}}(34{)}_{\mathrm{sys}}{\mathrm{fm}}^2$ for the mean squared axial charge radius, $g_P^{*}=9.03(47{)}_{\mathrm{stat}}(42{)}_{\mathrm{sys}}$ for the induced pseudoscalar charge; and $g_{\pi NN}=14.14(81{)}_{\mathrm{stat}}(85{)}_{\mathrm{sys}}$ for the pion-nucleon coupling. We also provide a parametrization of the axial form factor $G_A(Q^2)$ over the range $0\le Q^2\le 1{\mathrm{GeV}}^2$ for use in phenomenology and a comparison with other lattice determinations. We find that the various lattice data agree within 10% but are significantly different from the extraction of $G_A(Q^2)$ from the $\nu$-deuterium scattering data.

Mean-field model quantum field theories of hadrons were traditionally developed to describe cold and dense nuclear matter and are by now very well constrained from the recent neutron star merger observations. We show that when augmented with additional known hadrons and resonances but not included earlier, these mean-field models can be extended beyond its regime of applicability. Calculating some specific ratios of baryon number susceptibilities for finite temperature and moderate values of baryon densities within mean-field approximation, we show that these match consistently with the lattice QCD data available at lower densities, unlike the results obtained from a noninteracting hadron resonance gas model. We also estimate the curvature of the line of constant energy density, fixed at its corresponding value at the chiral crossover transition in QCD, in the temperature-density plane. The number density at low temperatures and high density is found to be about twice the nuclear saturation density. Moreover from this line we can indirectly constrain the critical endpoint of QCD to be beyond ${\mu }_B=596\mathrm{MeV}$ for temperature $\sim 125\mathrm{MeV}$.

Decays of the fully beauty four-quark structures $X_{4\mathrm{b}}$ and $T_{4\mathrm{b}}$ to $B$ meson pairs are investigated in the framework of the QCD three-point sum rule method. We model the scalar exotic mesons $X_{4\mathrm{b}}$ and $T_{4\mathrm{b}}$ as diquark-antidiquark systems composed of the axial-vector and pseudoscalar diquarks, respectively. The masses $m=(18540\pm 50)\mathrm{MeV}$ and $\tilde{m}=(18858\pm 50)\mathrm{MeV}$ of these compounds calculated in our previous articles fix possible decay channels of these particles. In the present work, we consider their decays to $B_q{\overline{B}}_q$ and $B_q^{*}{\overline{B}}_q^{*}$ ($q=u$, $d$, $s$, $c$) mesons. In the case of $X_{4\mathrm{b}}$, the mass of which is below the $2{\eta }_b$ threshold, these channels determine essential part of its full width ${\mathrm{\Gamma }}_{4\mathrm{b}}$. The tetraquark $T_{4\mathrm{b}}$ can decay to the pair ${\eta }_b{\eta }_b$; therefore, partial widths of processes with $B(B^{*})$ mesons in the final state permit us to refine our estimate for the full width of this particle. The predictions ${\mathrm{\Gamma }}_{4\mathrm{b}}=(9.6\pm 1.1)\mathrm{MeV}$ and ${\tilde{\mathrm{\Gamma }}}_{4\mathrm{b}}^{\text{Full}}=(144\pm 29)\mathrm{MeV}$ obtained in this article can be used in future experimental investigations of four $b$-quark mesons.

Studies related to $\mathrm{J}/\psi$ meson, a bound state of charm and anticharm quarks ($c\overline{c}$), in heavy-ion collisions, provide genuine testing grounds for the theory of strong interaction, quantum chromodynamics. To better understand the underlying production mechanism, cold nuclear matter effects, and influence from the quark-gluon plasma, baseline measurements are also performed in proton-proton ($pp$) and proton-nucleus ($p$-A) collisions. The inclusive $\mathrm{J}/\psi$ measurement has contributions from both prompt and nonprompt productions. The prompt $\mathrm{J}/\psi$ is produced directly from the hadronic interactions or via feed down from directly produced higher charmonium states, whereas nonprompt $\mathrm{J}/\psi$ comes from the decay of beauty hadrons. In experiments, $\mathrm{J}/\psi$ is reconstructed through its electromagnetic decays to lepton pairs, in either $e^{+}+e^{-}$ or ${\mu }^{+}+{\mu }^{-}$ decay channels. In this work, for the first time, machine learning techniques are implemented to separate the prompt and nonprompt dimuon pairs from the background to obtain a better identification of the $\mathrm{J}/\psi$ signal for different production modes. The study has been performed in $pp$ collisions at $\sqrt{s}=7$ and 13 TeV simulated using pythia8. Machine learning models such as XGBoost and LightGBM are explored. The models could achieve up to 99% prediction accuracy. The transverse momentum ($p_{\mathrm{T}}$) and rapidity ($y$) differential measurements of inclusive, prompt, and nonprompt $\mathrm{J}/\psi$, its multiplicity dependence, and the $p_{\mathrm{T}}$ dependence of fraction of nonprompt $\mathrm{J}/\psi$ ($f_{\mathrm{B}}$) are shown. These results are compared to experimental findings wherever possible.

The longitudinal and transverse spin transfers to $\mathrm{\Lambda }$ ($\overline{\mathrm{\Lambda }}$) hyperons in polarized proton-proton collisions are expected to be sensitive to the helicity and transversity distributions, respectively, of (anti)strange quarks in the proton, and to the corresponding polarized fragmentation functions. We report improved measurements of the longitudinal spin transfer coefficient, $D_{LL}$, and the transverse spin transfer coefficient, $D_{TT}$, to $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ in polarized proton-proton collisions at $\sqrt{s}=200\mathrm{GeV}$ by the STAR experiment at RHIC. The dataset includes longitudinally polarized proton-proton collisions with an integrated luminosity of $52{\mathrm{pb}}^{-1}$, and transversely polarized proton-proton collisions with a similar integrated luminosity. Both datasets have about twice the statistics of previous results and cover a kinematic range of $|{\eta }_{\mathrm{\Lambda }(\overline{\mathrm{\Lambda }})}|<1.2$ and transverse momentum $p_{T,\mathrm{\Lambda }(\overline{\mathrm{\Lambda }})}$ up to $8\mathrm{GeV}/c$. We also report the first measurements of the hyperon spin transfer coefficients $D_{LL}$ and $D_{TT}$ as a function of the fractional jet momentum $z$ carried by the hyperon, which can provide more direct constraints on the polarized fragmentation functions.

Transverse single-spin asymmetries $A_{\mathrm{N}}$ of forward neutrons at pseudorapidities larger than 6 had only been studied in the transverse momentum range of $p_{\mathrm{T}}<0.4\mathrm{GeV}/c$. The RHICf Collaboration has extended the previous measurements up to $1.0\mathrm{GeV}/c$ in polarized $p+p$ collisions at $\sqrt{s}=510\mathrm{GeV}$, using an electromagnetic calorimeter installed in the zero-degree area of the STAR detector at the Relativistic Heavy Ion Collider. The resulting $A_{\mathrm{N}}$ values increase in magnitude with $p_{\mathrm{T}}$ in the high longitudinal momentum fraction $x_{\mathrm{F}}$ range, but they reach a plateau at lower $p_{\mathrm{T}}$ for lower $x_{\mathrm{F}}$ values. For low transverse momenta, the $A_{\mathrm{N}}$’s show little $x_{\mathrm{F}}$ dependence and level off from intermediate values. For higher transverse momenta, the $A_{\mathrm{N}}$’s also show a tendency to reach a plateau at increased magnitudes. The results are consistent with previous measurements at lower collision energies, suggesting no $\sqrt{s}$ dependence of the neutron asymmetries. A theoretical model based on the interference of $\pi$ and $a_1$ exchange between two protons could partially reproduce the current results; however, an additional mechanism is necessary to describe the neutron $A_{\mathrm{N}}$’s over the whole kinematic region measured.

We report the first measurement of the atmospheric neutrino-oxygen neutral-current quasielastic (NCQE) cross section in the gadolinium-loaded Super-Kamiokande (SK) water Cherenkov detector. In June 2020, SK began a new experimental phase, named SK-Gd, by loading 0.011% by mass of gadolinium into the ultrapure water of the SK detector. The introduction of gadolinium to ultrapure water has the effect of improving the neutron-tagging efficiency. Using a 552.2 day dataset from August 2020 to June 2022, we measure the NCQE cross section to be $0.74\pm 0.22(\text{stat}{)}_{-0.15}^{+0.85}(\text{syst})\times {10}^{-38}{\mathrm{cm}}^2/\text{oxygen}$ in the energy range from 160 MeV to 10 GeV, which is consistent with the atmospheric neutrino-flux-averaged theoretical NCQE cross section and the measurement in the SK pure-water phase within the uncertainties. Furthermore, we compare the models of the nucleon-nucleus interactions in water and find that the binary cascade model and the Liège intranuclear cascade model provide a somewhat better fit to the observed data than the Bertini cascade model. Since the atmospheric neutrino-oxygen NCQE reactions are one of the main backgrounds in the search for diffuse supernova neutrino background (DSNB), these new results will contribute to future studies—and the potential discovery—of the DSNB in SK.

The quantum geometry arising in loop quantum gravity has been known to semiclassically lead to generalizations of length geometries. There have been several attempts to interpret these so-called twisted geometries and understand their role and fate in the continuum limit of the spin foam approach to quantum gravity. In this paper we offer a new perspective on this issue by showing that the twisted geometry of a four-simplex can be understood as arising from an area metric (in contrast to the more particular length metric). Such equivalence allows us to define notions like signature, generalized triangle inequalities and parallel transport for twisted geometries (now understood in a four-dimensional setting), exemplifying how it provides a new handle to understand them. Furthermore, it offers a new microscopic understanding of spin foam geometries which is notably supported by recent studies of the continuum effective dynamics of spin foams.