In recent work with Zhou, we studied classical interactions of matter with a “continuous spin” field, whose excitations have zero mass but nonzero spin Casimir (spin scale) $\rho$. We reported evidence that such theories are a calculable infrared deformation of familiar massless theories including electromagnetism. Building on the aforementioned work, this paper presents rules for computing scattering amplitudes involving charged scalar matter and continuous spin photons with nonzero spin scale. As a concrete example, we compute the pair annihilation and Compton scattering amplitudes in this theory and comment on their physical properties, including unitarity and scaling behavior at small and large $\rho$. Like the classical physics and soft factors studied in prior work, these amplitudes exhibit “helicity correspondence,” recovering familiar amplitudes at energy scales $\gg \rho$, but with calculable deviations that could be experimentally tested. These results bolster the conjecture that continuous spin particles with a very small $\rho$ could mediate long-range forces in nature (e.g., the photon could be a continuous spin particle), and extend the range of physical effects that could be used to test this hypothesis.

The absence of a breakthrough in directly observing dark matter (DM) through prominent large-scale detectors motivates the development of novel tabletop experiments probing more exotic regions of the parameter space. If DM contains ultralight bosonic particles, they would behave as a classical wave and could manifest through an oscillating force on baryonic matter that is coherent over $\sim {10}^6$ periods. Our Helium ultraLIght dark matter Optomechanical Sensor (HeLIOS) uses the high-$Q$ acoustic modes of superfluid helium-4 to resonantly amplify this signal. A superconducting reentrant microwave cavity enables sensitive optomechanical readout ultimately limited by thermal motion at millikelvin temperatures. Pressurizing the helium allows for the unique possibility of tuning the mechanical frequency to effectively broaden the DM detection bandwidth. We demonstrate the working principle of our prototype HeLIOS detector and show that future generations of HeLIOS could explore unconstrained parameter space for both scalar and vector ultralight DM after just an hour of integration time.

Recent years have seen much activity in searches for dark-sector messenger particles in the 10–100 MeV mass range, especially in view of a potential new light boson conjectured by the ATOMKI Collaboration, X17. Under the assumption that the messenger particle has definite parity and either zero or unit spin, quite stringent bounds already exist on its coupling to electrons and protons. Equally stringent bounds on the neutron coupling do not exist yet, but are nonetheless desirable. We explore how measurements of deuteron photodisintegration with a quasifree neutron can yield bounds on the neutron coupling, and compute projections for a potential measurement at the low-energy high-intensity electron scattering experiment MAGIX@MESA. The projected bounds are found to be competitive for an axial-vector or pseudoscalar scenario, but not for a vector or scalar scenario.

It is well known that the minimal renormalizable $SU(5)$ grand unified theory is ruled out: it predicts the same masses of down quarks and charged leptons, the gauge couplings do not unify, and neutrinos are massless. We show here that all this can be cured simultaneously by the addition of higher-dimensional effective operators. However, the theory lives on the edge since the unification scale turns out as low as roughly ${10}^{14}\mathrm{GeV}$, threatening proton longevity. If the lower bound on the proton lifetime was to be increased by an order of magnitude, the usual desert in energies between the weak and unification scales would be populated. We also revisit two minimal extensions of this theory that offer a dynamical seesaw origin of neutrino mass and discuss the resulting consequences.

In a recent publication we studied the decay rate of primordial black holes perceiving the dark dimension, an innovative five-dimensional (5D) scenario that has a compact space with characteristic length scale in the micron range. We demonstrated that the rate of Hawking radiation of 5D black holes slows down compared to 4D black holes of the same mass. Armed with our findings we showed that for a species scale of $\mathcal{O}({10}^{10}\mathrm{GeV})$, an all-dark-matter interpretation in terms of primordial black holes should be feasible for black hole masses in the range ${10}^{14}\lesssim M/\mathrm{g}\lesssim {10}^{21}$. As a natural outgrowth of our recent study, herein we calculate the Hawking evaporation of near-extremal 5D black holes. Using generic entropy arguments we demonstrate that Hawking evaporation of higher-dimensional near-extremal black holes proceeds at a slower rate than the corresponding Schwarzschild black holes of the same mass. Assisted by this result we show that if there were 5D primordial near-extremal black holes in nature, then a primordial black hole all-dark-matter interpretation would be possible in the mass range ${10}^5\sqrt{\beta }\lesssim M/\mathrm{g}\lesssim {10}^{21}$, where $\beta$ is a parameter that controls the difference between mass and charge of the associated near-extremal black hole.

Atomic dark matter is usually considered to be produced asymmetrically in the early Universe. In this work, we first propose that the symmetric atomic dark matter can be thermally produced through the freeze-out mechanism. The dominant atom antiatom annihilation channel is the atomic rearrangement. It has a geometrical cross section much larger than that of elementary fermions. After the atomic formation, this annihilation process further depletes dark matter particles and finally freezes out. To give the observed dark matter relic, the dark atoms are naturally ultraheavy, ranging from ${10}^6$ to ${10}^{10}\mathrm{GeV}$.

We propose a new method to calculate parton distribution functions (PDFs) from lattice correlations of boosted quarks and gluons in the Coulomb gauge. Compared to the widely used gauge-invariant Wilson-line operators, these correlations greatly simplify the renormalization thanks to the absence of linear power divergence. Additionally, they enable access to larger off-axis momenta under preserved 3D rotational symmetry, as well as enhanced long-range precision that facilitates the Fourier transform. We verify the factorization formula that relates this new observable to the quark PDF at one-loop order in perturbation theory. Moreover, through a lattice calculation of the pion valence quark PDF, we demonstrate the aforementioned advantage and features of the Coulomb gauge correlation and show that it yields consistent results with the gauge-invariant method. This opens the door to a more efficient way to calculate parton physics on the lattice.

We present results for the nucleon form factors: electric ($G_E$), magnetic ($G_M$), axial ($F_A$), induced pseudoscalar ($F_P$), and pseudoscalar ($G_P$) form factors, using the second PACS10 ensemble that is one of three sets of $2+1$ flavor lattice QCD configurations at physical quark masses in large spatial volumes [exceeding $(10\mathrm{fm}{)}^3$]. The second PACS10 gauge configurations are generated by the PACS Collaboration with the six stout-smeared $O(a)$ improved Wilson quark action and Iwasaki gauge action at the second gauge coupling $\beta =2.00$ corresponding to the lattice spacing of $a=0.063\mathrm{fm}$. We determine the isovector electric, magnetic and axial radii, and magnetic moment from the corresponding form factors, as well as the axial-vector coupling $g_A$. Combining our previous results for the coarser lattice spacing [E. Shintani et al., Phys. Rev. D 99, 014510 (2019); Phys. Rev. D 102, 019902(E) (2020)], the finite lattice spacing effects on the isovector radii, magnetic moment, and axial-vector coupling are investigated using the difference between the two results. It was found that the effect on $g_A$ is kept smaller than the statistical error of 2% while the effect on the isovector radii was observed as a possible discretization error of about 10%, regardless of the channel. We also report the partially conserved axial-vector current relation using a set of nucleon three-point correlation functions in order to verify the effect by $O(a)$ improvement of the axial-vector current.

Recent data for the masses of $D$ and $D^{*}$ mesons determined using methods of lattice QCD for several values of the charm quark mass different from its physical mass are analyzed in heavy quark effective theory. Nonperturbative parameters are extracted that arise at order $\mathcal{O}(1/m_c)$ in the heavy quark mass expansion of a heavy-light meson mass. The determined parameters are used to establish the charm quark masses corresponding to the employed lattice sets.

In this work, we attack the problem of “chiral phase instability” ($\chi \mathrm{PI}$) in a quantum chromodynamics (QCD) system under a parallel and constant electromagnetic field. The $\chi \mathrm{PI}$ refers to the fact that, when $I_2\equiv \mathbf{E}·\mathbf{B}$ is larger than the threshold $I_2^c$, no homogeneous solution can be found for $\sigma$ or ${\pi }^0$ condensate, and the chiral phase $\theta$ becomes unstable. Within the two-flavor chiral perturbation theory, we obtain an effective Lagrangian density for $\theta (x)$ where the chiral anomalous Wess-Zumino-Witten term is found to play a role of “source” to the “potential field” $\theta (x)$. The Euler-Lagrangian equation is applied to derive the equation of motion for $\theta (x)$, and physical solutions are worked out for several shapes of systems. In the case $I_2>I_2^c$, it is found that the $\chi \mathrm{PI}$ actually implies an inhomogeneous QCD phase with $\theta (x)$ spatially dependent. By its very nature, the homogeneous-inhomogeneous phase transition is of pure topological and second order at $I_2^c$. Finally, the work is extended to the three-flavor case, where an inhomogeneous $\eta$ condensation is also found to be developed for $I_2>I_2^c$. Correspondingly, there is a second critical point, $I_2^{c^{\prime }}=24.3I_2^c$, across which the transition is also of topological and second order by its very nature.

The hadronization procedure of the QGSJET-III Monte Carlo (MC) generator of high energy hadronic interactions is discussed. Selected results of the model, regarding production spectra of secondary particles, are presented in comparison to experimental data and to the corresponding predictions of the QGSJET-II-04 MC generator. The model is applied to calculations of basic characteristics of extensive air showers initiated by cosmic ray interactions in the atmosphere and the results are compared to predictions of other MC generators of cosmic ray interactions.

We have studied the mass spectra of doubly charmed pentaquark states in the ${\mathrm{\Lambda }}_c^{(*)}{D}^{(*)}$ and ${\mathrm{\Sigma }}_c^{(*)}{D}^{(*)}$ channels with $J^P=1/2^{\pm }$, $3/2^{\pm }$, and $5/2^{\pm }$ within the framework of quantum chromodynamics sum rules. We use the parity projected sum rules to separate the contributions of negative and positive parities from the two-point correlations induced by the pentaquark interpolating currents. Our results show that the bound states of $P_{cc}$ pentaquarks may exist in the ${\mathrm{\Lambda }}_{c}D({\frac{1}{2}}^{-})$, ${\mathrm{\Sigma }}_{c}D({\frac{1}{2}}^{-})$, ${\mathrm{\Sigma }}_c{D}^{*}({\frac{3}{2}}^{-})$, ${\mathrm{\Lambda }}_c^{*}D({\frac{3}{2}}^{-})$, ${\mathrm{\Lambda }}_c^{*}{D}^{*}({\frac{5}{2}}^{-})$ channels with negative-parity and ${\mathrm{\Sigma }}_{c}D({\frac{1}{2}}^{+})$, ${\mathrm{\Sigma }}_c{D}^{*}({\frac{3}{2}}^{+})$, ${\mathrm{\Sigma }}_c^{*}D({\frac{3}{2}}^{+})$ channels with positive-parity, since their masses are predicted to be lower than the corresponding meson-baryon thresholds. However, they are still allowed to decay into the ${\mathrm{\Xi }}_{cc}^{(*)}\pi$ final states via strong interaction. The triply charged $P_{cc}^{+++}(ccuu\overline{d})$ and neutral $P_{cc}^0(ccdd\overline{u})$ in the isospin quartet would definitely be pentaquark states due to their exotic charges. We suggest searching for these characteristic doubly charmed pentaquark signals in the $P_{cc}^{+++}\to {\mathrm{\Xi }}_{cc}^{(*)++}{\pi }^{+}/{\rho }^{+}$, ${\mathrm{\Sigma }}_c^{(*)++}{D}^{(*)+}$ and $P_{cc}^0\to {\mathrm{\Xi }}_{cc}^{(*)+}{\pi }^{-}/{\rho }^{-}$, ${\mathrm{\Sigma }}_c^{(*)0}{D}^{(*)0}$ decays in the near future.

We determine the mass spectroscopy and light-front wave functions (LFWFs) of the $\rho$-meson by solving the holographic Schrödinger equation of light-front chiral QCD along with the ’t Hooft equation of ($1+1$)-dimensional QCD in the large $N_c$ limit. Subsequently, we utilize the obtained LFWFs in conjunction with the color glass condensate dipole cross section to calculate the cross sections for the diffractive $\rho$-meson electroproduction. Our spectroscopic results align well with the experimental data. Predictions for the diffractive cross sections demonstrate good consistency with the available experimental data at different energies from H1 and ZEUS collaborations. Additionally, we show that the resulting LFWFs for the $\rho$-meson can effectively describe various properties, including its decay constant, distribution amplitudes, electromagnetic form factors, charge radius, magnetic and quadrupole moments. Comparative analyses are conducted with experimental measurements and the available theoretical predictions.

We investigate the Wigner distributions of $\overline{u}$ and $\overline{d}$ quarks in a proton using the overlap representation within the light cone formalism. Using the light-cone wave functions which are obtained from the baryon-meson fluctuation model in terms of the $|q\overline{q}B⟩$ Fock states, we calculate the Wigner distributions for the unpolarized/longitudinally polarized sea quarks in an unpolarized/longitudinally polarized proton. The Wigner distributions can be obtained through a Fourier transform on the generalized transverse-momentum dependent parton distributions (GTMDs). We also calculate the GTMDs of $\overline{u}$ and $\overline{d}$ quarks in the intermediate step. Numerical results for the Wigner distributions of $\overline{u}$ and $\overline{d}$ quarks in transverse momentum space, impact parameter space and the mixed plane are presented. We also study the orbital angular momentum and the spin-orbit correlations of the sea quarks.

We present a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Previous fits of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain the strangeness contribution to the axial form factor $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45{\mathrm{GeV}}^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and antineutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed: a relativistic Fermi gas model, the superscaling approximation model, and a spectral function model. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE.

We consider the potential for a 10 kg undoped cryogenic CsI detector operating at the Spallation Neutron Source to measure coherent elastic neutrino-nucleus scattering and its sensitivity to discover new physics beyond the standard model (BSM). Through a combination of increased event rate, lower threshold, and good timing resolution, such a detector would significantly improve on past measurements. We considered tests of several BSM scenarios such as neutrino nonstandard interactions and accelerator-produced dark matter. This detector’s performance was also studied for relevant questions in nuclear physics and neutrino astronomy, namely the weak charge distribution of Cs and I nuclei and detection of neutrinos from a core-collapse supernova.

We develop a new formula called a mode recombination formula, and we can recast the effective potential at finite temperature in one-loop approximation for fermion and scalar fields on the $D$-dimensional spacetime, $S_{\tau }^1\times R^{D-(p+1)}\times {\prod }_{i=1}^p{S}_i^1$ into a convenient form for discussing nonanalytic terms, which cannot be written in the form of any positive integer power of the field-dependent mass squared, in the effective potential. The formula holds irrespective of whether the field is a fermion or a scalar and of boundary conditions for spatial $S_i^1$ directions and clarifies the importance of zero modes in the Matsubara and Kaluza-Klein modes for the existence of the nonanalytic terms. The effective potential is drastically simplified further to obtain the nonanalytic terms in easier and more transparent way. In addition to reproducing previous results, we find that there exists no nonanalytic term for the fermion field with arbitrary boundary condition for the spatial $S_i^1$ direction, which is also the case for the scalar field with the antiperiodic boundary condition for the spatial direction.

Observation of gravitational waves from inspiralling binary black holes has offered a unique opportunity to study the physical parameters of the component black holes. To infer these parameters, Bayesian methods are employed in conjunction with general relativistic waveform models that describe the source’s inspiral, merger, and ringdown. The results depend not only on the accuracy of the waveform models but also on the underlying fiducial prior distribution used for the analysis. In particular, when the premerger phase of the signal is barely observable within the detectors’ bandwidth, as is currently the case with intermediate-mass black hole binary signals in ground-based gravitational wave detectors, different prior assumptions can lead to different interpretations. In this study, we utilize the gravitational-wave inference library, parallel bilby, to evaluate the impact of mass prior choices on the parameter estimation of intermediate-mass black hole binary signals. While previous studies focused primarily on analysing event data, we offer a broader, more controlled study by using simulations. Our findings suggest that the posteriors in total mass, mass ratio and luminosity distance are contingent on the assumed mass prior distribution used during the inference process. This is especially true when the signal lacks sufficient premerger information and/or has inadequate power in the higher-order radiation multipoles. In conclusion, our study underscores the importance of thoroughly investigating similarly heavy events in current detector sensitivity using a diverse choice of priors. Absent such an approach, adopting a flat prior on the binary’s redshifted total mass and mass ratio emerges as a reasonable choice, preventing biases in the detector-frame mass posteriors.

Using Ernst formalism, the stationary axisymmetric black hole solution in Einstein dark matter–dark energy gravity has been elaborated. The dark sector was chosen as a dark photon concept, where an auxiliary $U(1)$-gauge field coupled to ordinary Maxwell one was introduced, while dark energy was modeled by the existence of a positive cosmological constant. Refining our studies to the case of a vanishing cosmological constant, the uniqueness theorem for the black hole in question has been proved.

It is shown that the spectral amplitude of gravitational wave ringdown of a Kerr black hole sourced by an extreme mass ratio merger can be modeled by the greybody factor, which quantifies the scattering nature of the black hole geometry. The estimation of the mass and spin of the remnant is demonstrated by fitting the greybody factor to gravitational wave data without using black hole quasinormal modes. We propose that the ringdown modeling with the greybody factor may strengthen the test of gravity as one can avoid the possible overfitting issue and the start time problem in the ringdown modeling with superposed quasinormal modes.