We present a concrete realization of the sound speed resonance (SSR) mechanism for primordial black hole (PBH) formation within a specific model of Dirac-Born-Infeld (DBI) inflation. We perform a perturbative approach to phenomenologically construct such a viable DBI inflation model that involves the nonoscillating stage and the oscillating stage, with a type of specific forms of the warp factor and the potential. We show that the continuous but nonsmooth conjunction of sound speed between two stages does not yield manifest effects on the phenomenology of SSR, and thus, our model gives rise to the same PBH mass spectrum as the original predictions of SSR. Additionally, we also demonstrate that the violation of adiabaticity of the Mukhanov-Sasaki equation does not affect the comoving curvature perturbation after Hubble crossing in the nonresonant region. Making use of observational data, we derive various cosmological constraints on the parameter space. Our analyses show that the predicted tensor-to-scalar ratio is typically small, while the amplitude of primordial non-Gaussianity can meet with cosmic microwave background bounds, and additionally, the consistency relation for single-field slow-roll inflation is softly violated in our case due to the small sound speed variations.

Scalar fields can give rise to confined structures, such as boson stars or $Q$-balls. These objects are interesting hypothetical new “dark matter stars,” but also good descriptions of dark matter haloes when the fields are ultralight. Here, we study the dynamical response of such confined bosonic structures when excited by external matter (stars, planets or black holes) in their vicinities. Such perturbers can either be plunging through the bosonic configuration or undergoing periodic motion around its center. Our setup can also efficiently describe the interaction between a moving, massive black hole and the surrounding environment. It also depicts dark matter depletion as a reaction to an inspiralling binary within the halo. We calculate total energy loss, and linear and angular momenta radiated during these processes, and perform the first self-consistent calculation of dynamical friction acting on moving bodies in these backgrounds. We show that the gravitational collapse to a supermassive black hole at the center of a Newtonian boson star (NBS) is accompanied by a small change in the surrounding core. The NBS eventually gets accreted, but only on times larger than a Hubble scale for astrophysical parameters. Stellar or supermassive binaries are able to “stir” the NBS and lead to scalar radiation. For binaries in the LIGO or LISA band, close to coalescence, scalar emission affects the waveform at leading $-6$ PN order with respect to the dominant quadrupolar term; the coefficient is too small to allow detection by next-generation interferometers. Our results provide a complete picture of the interaction between black holes or stars and the ultralight dark matter environment they live in.

Rare decays of $K$ and $B$ mesons provide a powerful probe of dark sectors with light new particles. We show that the pair production of $O(100\mathrm{MeV})$ dark states can be probed with the decays of $K_L$ mesons, owing to the enhanced two-body kinematics, $K_L\to X_1{X}_2$ or $X_2{X}_2$. If either of these two particles is unstable, e.g., $X_2\to X_1{\pi }^0$, $X_2\to X_1\gamma$ or $X_{1,2}\to \gamma \gamma$, such decays could easily mimic $K_L\to {\pi }^0\nu \overline{\nu }$ signatures, while not being ruled out by the decays of charged kaons. We construct explicit models that have enhanced $K_L$ decay signatures, and are constrained by the results of the KOTO experiment. We note that recently reported excess events can also be accommodated while satisfying all other constraints ($B$ decays, colliders, beam dumps). These models are based on the extensions of the gauge and/or scalar sector of the theory. The lightest of $X_{1,2}$ particles, if stable, could constitute the entirety of dark matter.

We calculate the low-lying spectrum of charmed baryons in lattice QCD on the ${32}^3\times 64$, $N_f=2+1$ PACS-CS gauge configurations at the almost physical pion mass of $\sim 156\mathrm{MeV}/c^2$. By employing a set of interpolating operators with different Dirac structures and quark-field smearings for the variational analysis, we extract the ground and first few excited states of the spin-$1/2$ and spin-$3/2$, singly, doubly, and triply charmed baryons. Additionally, we study the ${\mathrm{\Xi }}_c\text{−}{\mathrm{\Xi }}_c^{\prime }$ mixing and the operator dependence of the excited states in a variational approach. We identify several states that lie close to the experimentally observed excited states of the ${\mathrm{\Sigma }}_c$, ${\mathrm{\Xi }}_c$ and ${\mathrm{\Omega }}_c$ baryons, including some of the ${\mathrm{\Xi }}_c$ states recently reported by LHCb. Our results for the doubly and triply charmed baryons are suggestive for future experiments.

It is widely expected that at sufficiently high temperatures order is always lost, e.g., magnets lose their ferromagnetic properties. We pose the question of whether this is always the case in the context of quantum field theory in $d$ space dimensions. More concretely, one can ask whether there exist critical points (CFTs) which break some global symmetry at arbitrary finite temperature. The most familiar CFTs do not exhibit symmetry breaking at finite temperature, and moreover, in the context of the $\mathrm{AdS}/\mathrm{CFT}$ correspondence, critical points at finite temperature are described by an uncharged black brane which obeys a no-hair theorem. Yet, we show that there exist CFTs which have some of their internal symmetries broken at arbitrary finite temperature. Our main example is a vector model which we study both in the epsilon expansion and arbitrary rank as well as the large rank limit (and arbitrary dimension). The large rank limit of the vector model displays a conformal manifold, a moduli space of vacua, and a deformed moduli space of vacua at finite temperature. The appropriate Nambu-Goldstone bosons including the dilatonlike particle are identified. Using these tools we establish symmetry breaking at finite temperature for finite small $\epsilon$. We also prove that a large class of other fixed points, which describe some of the most common quantum magnets, indeed behave as expected and do not break any global symmetry at finite temperature. We discuss some of the consequences of finite temperature symmetry breaking for the spectrum of local operators. Finally, we propose a class of fixed points which appear to be possible candidates for finite temperature symmetry breaking in $d=2$.

Neutron stars (NSs) in scalar-tensor (ST) theories of gravitation can acquire scalar charges and generate distinct spacetimes from those in general relativity (GR) through the celebrated phenomenon of spontaneous scalarization. Taking on an ST theory with the mass term of the scalar field, we determine the theory parameter space for spontaneous scalarization by investigating the linearized scalar field equation. Then the full numerical solutions for slowly rotating NSs are obtained and studied in great detail. The resulted spacetime is used to calculate test-particle geodesics. The lightlike geodesics are used to construct the profile of x-ray radiation from a pair of hot spots on the surface of scalarized NSs, which potentially can be compared with the data from the Neutron star Interior Composition Explorer (NICER) mission for testing the ST theory.

We present a systematic comparison of the binary black hole BBH signal waveform reconstructed by two independent and complementary approaches used in LIGO and Virgo source inference: a template-based analysis and a morphology-independent analysis. We apply the two approaches to real events and to two sets of simulated observations made by adding simulated BBH signals to LIGO and Virgo detector noise. The first set is representative of the ten BBH events in the first gravitational wave transient catalog (GWTC-1). The second set is constructed from a population of BBH systems with total masses and signal strengths in the ranges that ground based detectors are typically sensitive. We find that the reconstruction quality of the GWTC-1 events is consistent with the results of both sets of simulated signals. We also demonstrate a simulated case, where the presence of a mismodeled effect in the observed signal, namely higher order modes, can be identified through the morphology-independent analysis. This study is relevant for currently progressing and future observational runs by LIGO and Virgo.

We investigate the appropriateness of the use of different Lagrangians to describe various components of the cosmic energy budget, discussing the degeneracies between them in the absence of nonminimal couplings to gravity or other fields, and clarifying some misconceptions in the literature. We further demonstrate that these degeneracies are generally broken for nonminimal coupled fluids, in which case the identification of the appropriate on-shell Lagrangian may become essential in order to characterize the overall dynamics. We then show that models with the same on-shell Lagrangian may have different proper energy densities and use this result to map dark energy models into unified dark energy models in which dark matter and dark energy are described by the same perfect fluid. We determine the correspondence between their equation of state parameters and sound speeds, briefly discussing the linear sound speed problem of unified dark energy models as well as a possible way out associated with the nonlinear dynamics.

The superradiant instability of black hole space-times has been used to place limits on ultra-light bosonic particles. While the initial growth of the mode is gravitational and thus model independent, the ability to place a limit on new particles requires the mode to grow unhindered to a large number density. Nonlinear interactions between the particle and other light degrees of freedom that are mediated through higher-dimension operators can damp this growth, eliminating the limit. However, these nonlinearities may also destroy a cosmic abundance of these light particles, an attractive avenue for their discovery in several experiments. We study the specific example of the QCD axion and show that it is easy to construct models where these nonlinearities eliminate limits from superradiance while preserving their cosmic abundance.

We present results on the isovector momentum fraction, $⟨x{⟩}_{u-d}$, helicity moment, $⟨x{⟩}_{\mathrm{\Delta }u-\mathrm{\Delta }d}$, and the transversity moment, $⟨x{⟩}_{\delta u-\delta d}$, of the nucleon obtained using nine ensembles of gauge configurations generated by the MILC Collaboration using $2+1+1$-flavors of dynamical highly improved staggered quarks. The correlation functions are calculated using the Wilson-Clover action, and the renormalization of the three operators is carried out nonperturbatively on the lattice in the ${\mathrm{RI}}^{\prime }\text{−}\text{MOM}$ scheme. The data have been collected at lattice spacings $a\approx 0.15$, 0.12, 0.09, and 0.06 fm and $M_{\pi }\approx 310$, 220, and 135 MeV, which are used to obtain the physical values using a simultaneous chiral-continuum-finite-volume fit. The final results, in the $\overline{\mathrm{MS}}$ scheme at 2 GeV, are $⟨x{⟩}_{u-d}=0.173(14)(07)$, $⟨x{⟩}_{\mathrm{\Delta }u-\mathrm{\Delta }d}=0.213(15)(22)$, and $⟨x{⟩}_{\delta u-\delta d}=0.208(19)(24)$, where the first error is the overall analysis uncertainty and the second is an additional systematic uncertainty due to possible residual excited-state contributions. These results are consistent with other recent lattice calculations and phenomenological global fit values.

Differential equations for the one-loop vertex diagram in heavy quark effective theory (HQET) with arbitrary self-energy insertions and arbitrary residual energies are reduced to the $ϵ$ form and used to obtain the $ϵ$ expansion in terms of Goncharov polylogarithms.

Quasi parton distributions (quasi-PDFs) are currently under intense investigation. Quasi-PDFs are defined through spatial correlation functions and are thus accessible in lattice QCD. They gradually approach their corresponding standard (light-cone) PDFs as the hadron momentum increases. Recently, we investigated the concept of quasi-distributions in the case of generalized parton distributions (GPDs) by calculating the twist-2 vector GPDs in the scalar diquark spectator model. In the present work, we extend this study to the remaining six leading-twist GPDs. For large hadron momenta, all quasi-GPDs analytically reduce to the corresponding standard GPDs. We also study the numerical mismatch between quasi-GPDs and standard GPDs for finite hadron momenta. Furthermore, we present results for quasi-PDFs, and explore higher-twist effects associated with the parton momentum and the longitudinal momentum transfer to the target. We study the dependence of our results on the model parameters as well as the type of diquark. Finally, we discuss the lowest moments of quasidistributions, and elaborate on the relation between quasi-GPDs and the total angular momentum of quarks. The moment analysis suggests a preferred definition of several quasidistributions.

We compute a light front wave function for heavy vector mesons based on long-distance matrix elements constrained by decay width analyses in the nonrelativistic QCD framework. Our approach provides a systematic expansion of the wave function in quark velocity. The first relativistic correction included in our calculation is found to be significant and crucial for a good description of the HERA exclusive $\mathrm{J}/\psi$ production data. When looking at cross section ratios between nuclear and proton targets, the wave function dependence does not cancel out exactly. In particular the fully nonrelativistic limit is found not to be a reliable approximation even in this ratio. The important role of the Melosh rotation to express the rest frame wave function on the light front is illustrated.

We investigate photoproduction of axial vector meson $f_1(1285)$ based on the CLAS experiment $\gamma p\to p{f}_1(1285)\to p\eta {\pi }^{+}{\pi }^{-}$ using the Regge model for ${\rho }^0+\omega$ exchanges. The combined analysis of $\gamma p\to p{\eta }^{\prime }\to p\eta {\pi }^{+}{\pi }^{-}$ reaction including $\eta (1295)$ is accompanied to evaluate the decay mode $\eta (1295)\to \eta {\pi }^{+}{\pi }^{-}$ from the potential overlap with the $f_1$ reaction. The predominance of ${\rho }^0(770)$ exchange over the $\omega (782)$ with the coupling constant $\gamma {\rho }^0{f}_1$ extracted from the CLAS experiment leads to a good description of the measured cross sections for $f_1$, while the scale of the cross section is corrected by the branching fraction ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$ and $f_1\to \eta {\pi }^{+}{\pi }^{-}$, respectively. As an extension to study the nonmesonic production mechanism, the Primakoff effect by the virtual photon exchange is investigated in the exclusive reaction $\gamma p\to p{f}_1$ up to $\sqrt{s}\approx 50\mathrm{GeV}$, playing role similar to the Pomeron in the vector meson photoproduction at high energies. Such a unique role of the virtual photon exchange similar to the $f_1$ case is identified up to $\sqrt{s}\approx 250\mathrm{GeV}$ in the $\gamma p\to p{\pi }^0$ and $\gamma p\to p\eta$ as well as $\gamma p\to p{\eta }^{\prime }$ reactions.

We propose a novel analysis strategy, which leverages the unique capabilities of the DUNE experiment, to study tau neutrinos. We integrate collider physics ideas, such as jet clustering algorithms in combination with machine learning techniques, into neutrino measurements. Through the construction of a set of observables and kinematic cuts, we obtain a superior discrimination of the signal ($S$) over the background ($B$). In a single year, using the nominal neutrino beam mode, DUNE may achieve $S/\sqrt{B}$ of 3.3 and 2.3 for the hadronic and leptonic decay channels of the tau respectively. Operating in the tau-optimized beam mode would increase $S/\sqrt{B}$ to 8.8 and 11 for each of these channels. We premier the use of the analysis software rivet, a tool ubiquitously used by the LHC experiments, in neutrino physics. For wider accessibility, we provide our analysis code.

This paper presents an update to the MK model [M. Kabirnezhad, Phys. Rev. D 97, 013002 (2018)], which was developed to describe single pion production in neutrino-nucleon interactions. Originally, the MK model used the helicity amplitudes and the hadronic current form factors of the Rein and Sehgal model [Ann. Phys. (N.Y.) 50, 189 (1968)]. The update includes a new definition for the helicity amplitudes in the first and second resonance regions and new vector-current form factors. Fits to electron-proton scattering data were used to determine these vector-current form factors and to assign errors to the constrained free parameters of the model.

Potential applications of neutrino detection to nuclear security have been discussed since the 1970s. Recent years have seen great progress in detector technologies based on inverse beta decay, with the demonstration of ton-scale surface-level detectors capable of high quality neutrino spectrum measurements. In 2017, coherent elastic neutrino nucleus scattering was experimentally confirmed with neutrinos from stopped pion decay, and there are a number of experiments aimed at seeing this process with reactor neutrinos. The large cross section and thresholdless nature of this reaction make it plausible to consider it for applications to nuclear security. Here we present a first direct comparison of the two reaction modes.

The first observation of the decay $B^0\to D^0{\overline{D}}^0{K}^{+}{\pi }^{-}$ is reported using proton-proton collision data corresponding to an integrated luminosity of $4.7{\mathrm{fb}}^{-1}$ collected by the LHCb experiment in 2011, 2012 and 2016. The measurement is performed in the full kinematically allowed range of the decay outside of the $D^{*-}$ region. The ratio of the branching fraction relative to that of the control channel $B^0\to D^{*-}{D}^0{K}^{+}$ is measured to be $\mathcal{R}=(14.2\pm 1.1\pm 1.0)\%$, where the first uncertainty is statistical and the second is systematic. The absolute branching fraction of $B^0\to D^0{\overline{D}}^0{K}^{+}{\pi }^{-}$ decays is thus determined to be $\mathcal{B}(B^0\to D^0{\overline{D}}^0{K}^{+}{\pi }^{-})=(3.50\pm 0.27\pm 0.26\pm 0.30)\times {10}^{-4}$, where the third uncertainty is due to the branching fraction of the control channel. This decay mode is expected to provide insights to spectroscopy and the charm-loop contributions in rare semileptonic decays.

We present a method that is optimized to explicitly obtain all the constraints and thereby count the propagating degrees of freedom in (almost all) manifestly first-order classical field theories. Our proposal uses as its only inputs a Lagrangian density and the identification of the a priori independent field variables it depends on. This coordinate-dependent, purely Lagrangian approach is complementary to and in perfect agreement with the related vast literature. Besides, generally overlooked technical challenges and problems derived from an incomplete analysis are addressed in detail. The theoretical framework is minutely illustrated in the Maxwell, Proca and Palatini theories for all finite $d\ge 2$ spacetime dimensions. Our novel analysis of Palatini gravity constitutes a noteworthy set of results on its own. In particular, its computational simplicity is visible, as compared to previous Hamiltonian studies. We argue for the potential value of both the method and the given examples in the context of generalized Proca and their coupling to gravity. The possibilities of the method are not exhausted by this concrete proposal.

We study the properties of the transition probability and entanglement harvesting phenomenon for circularly accelerated detectors locally interacting with massless scalar fields. The dependence of the transition probability on the parameters associated with the circular motion is first analyzed in detail. By a cross-comparison with the situation of the uniformly accelerated motion, we obtain that the transition probability and the possible thermalization behavior for detectors rotating with an extremely large circular radius are analogous to that for uniformly accelerated detectors, but for a very small linear speed and a large acceleration, the effective temperature which characterizes the detectors’ thermalization in a finite duration is much lower than that for uniformly accelerated detectors. We then focus on the phenomenon of entanglement harvesting in two special situations of circular trajectories, i.e., the coaxial rotation and the mutually perpendicular axial rotation by examining the concurrence as the entanglement measure in detail. We find that when two circularly accelerated detectors have equivalent acceleration and size of circular trajectory, the harvested entanglement rapidly decays with increasing acceleration or separation between two detectors. In contrast with the situation of uniform acceleration, the angular velocity would have significant impacts on entanglement harvesting. Especially for those detectors circularly moving in different directions, both the acceleration and trajectory radius play an important inhibiting role in entanglement harvesting. When two circularly accelerated detectors have different values of acceleration or angular velocity, we find that the entanglement can still be extracted by such detectors, even in the situation that one detector is at rest and the other is in a circular motion.