We present a detailed analysis of the polarized and the unpolarized deep-inelastic scattering structure functions of the proton, $g_1^p$ and $F_2^p$ respectively, in the context of a holographic dual description based on type-IIB superstring theory. We compare this description with experimental data and quantum chromodynamics estimates computed at leading, next-to-leading and next-to-next-to-leading order in perturbation. We confront the predictions of a holographic dual model and those of perturbative QCD for $g_1^p$ at the kinematics that will be probed by the forthcoming electron-ion collider. We find that the extrapolation of $g_1^p$ to very small values the Bjorken variable computed with a holographic Pomeron model based on actual data at higher-momentum fractions is always positive and differs significantly with standard projections based on perturbative QCD.

We propose a model with two different extra $U(1)$ gauge symmetries; muon minus tauon symmetry $U(1{)}_{L_{\mu }-L_{\tau }}$ and hidden symmetry $U(1{)}_H$. Then, we explain the muon anomalous magnetic moment, semileptonic decays $b\to s\ell \overline{\ell }$, and dark matter. In particular, we find an intriguing dark matter candidate to be verified by Hyper-Kamiokande and JUNO in the future, that require neutrinophilic DM with rather light-dark matter $\text{mass}\sim \mathcal{O}(10)\mathrm{MeV}$.

Searches for new neutral Higgs bosons of an extended Higgs sector at the LHC can be interpreted in the framework of the two-Higgs doublet model. By employing generic flavor-aligned Higgs–fermion Yukawa couplings, we propose an analysis that uses experimental data to determine whether flavor alignment is a consequence of a symmetry that is either exact or at most softly broken. We illustrate our proposal in two different scenarios based on a few 3 sigma (local) excesses observed by the ATLAS and CMS Collaborations in their searches for heavy scalars. In scenario 1, an excess of events is interpreted as $A\to ZH\to {\ell }^{+}{\ell }^{-}b\overline{b}$ (where $\ell =e$ or $\mu$), with the $CP$-odd and $CP$-even neutral scalar masses given by $m_A=610\mathrm{GeV}$ and $m_H=290\mathrm{GeV}$, respectively. In scenario 2, an excess of events in the production of $t\overline{t}$ and ${\tau }^{+}{\tau }^{-}$ final states is interpreted as decays of a $CP$-odd scalar of mass $m_A=400\mathrm{GeV}$. Scenario 1 is consistent with type-I Yukawa interactions, which can arise in a 2HDM subject to a softly-broken ${\mathbb{Z}}_2$ discrete symmetry. Scenario 2 is inconsistent with a symmetry-based flavor alignment, but can be consistent with more general flavor-aligned Higgs–fermion Yukawa couplings.

We study the dependence of soft contribution to the energy loss of a test parton moving with a high velocity on the chiral imbalance and magnetic field in the QCD medium. A semiclassical approach is adopted to estimate the parton energy loss that takes into account the back-reaction on the parton due to the polarization effects of the QCD medium while traversing through the medium. We find that the motion of the parton is sensitive to the chiral asymmetry in the medium. Further, we investigate the effect of magnetic field-induced anisotropy on the energy transfer between the moving parton and the medium. Our results show that the energy loss of the parton is strongly influenced by the strength of the magnetic field as well as the relative orientation of the motion of the parton and the direction of the magnetic field in the medium.

The recently discovered ${\eta }_1(1855)$ and the previously observed ${\pi }_1(1600)$ state present a valuable opportunity for the investigation of the $J^{P(C)}=1^{-(+)}$ light hybrid nonet. In this study, we employ a semirelativistic quark potential model to examine the masses of the $J^{P(C)}=1^{-(+)}$ light hybrid states. The static potential, which portrays the confinement force between the quark-antiquark pair in a hybrid system, is borrowed from the SU(3) lattice gauge theory. Additionally, we utilize a constituent gluon model to analyze the strong decay characteristics of these light $1^{-+}$ hybrids. Our findings suggest that the ${\pi }_1(1600)$ and ${\eta }_1(1855)$ states could be potential candidates for $1^{-+}$ $(u\overline{u}-d\overline{d})g/\sqrt{2}$ and $s\overline{s}g$ hybrids, respectively. To ensure comprehensiveness, we also investigate the isospin partners of the ${\pi }_1(1600)$ and ${\eta }_1(1855)$ states within the $1^{-(+)}$ nonet—specifically, the $(u\overline{u}+d\overline{d})g/\sqrt{2}$ and $s\overline{q}g$ ($q=u$ and $d$ quarks) states. We propose some potential decay channels which could be explored in experimental settings to detect these undiscovered states.

Effects of the $U(1{)}_A$ axial anomaly on the mass spectrum of singly heavy baryons (SHBs) is studied in terms of the chiral effective theory based on the chiral linear representation for light flavors. We consider SHBs made of both three quarks ($Qqq$) and five quarks ($Qqqq\overline{q}$). For the three-quark SHBs, we prove that the inverse mass hierarchy for the negative-parity ${\mathrm{\Lambda }}_c$ and ${\mathrm{\Xi }}_c$ is realized only when the $U(1{)}_A$ anomaly is present. For the five-quark SHBs, in contrast, it is found that the $U(1{)}_A$ anomaly does not change the mass spectrum at the leading order, and accordingly, their decay properties induced by emitting a pseudoscalar meson are not affected by the anomaly. Moreover, taking into account small mixings between the three-quark and five-quark SHBs, we find that the observed ${\mathrm{\Xi }}_c$ excited state, either ${\mathrm{\Xi }}_c(2923)$ or ${\mathrm{\Xi }}_c(2930)$, can be consistently regarded as a negative-parity SHB that is dominated by the five-quark component. We also predict a new negative-parity five-quark dominant ${\mathrm{\Lambda }}_c$, whose mass is around 2700 MeV and the decay width is of order a few MeV, which provides useful information for future experiments to check our description.

The effect of rotation on the formation of the magnetic dual chiral density wave (MDCDW) in a dense and magnetized cold quark matter is studied. This phase is supposed to exist in the extreme conditions prevailing, e.g., in a neutron star. These conditions are, apart from high densities and strong magnetic fields, a relatively large angular velocity. To answer the question of whether the rotation enhances or suppresses the formation of this phase, we first determine the effect of rotation on the energy dispersion relation of a fermionic system in the presence of a constant magnetic field and then focus on the thermodynamic potential of the model at low temperature $T$ and finite chemical potential $\mu$. The thermodynamic potential consists, in particular, of an anomalous part leading to certain topological effects. We show that in comparison with the nonrotating case, a term proportional to the angular velocity appears in this anomalous potential. We then solve the corresponding gap equations to the chiral and spatial modulation condensates and study the dependence of these dynamical variables on the chemical potential ($\mu$), magnetic field ($eB$), and angular velocity ($\mathrm{\Omega }$). It turns out that the interplay between these parameters suppresses the formation of the MDCDW phase in relevant regimes for cold neutron stars. This is interpreted as the manifestation of the inverse magnetorotational catalysis, which is also reflected in the phase portraits $eB\text{−}\mu$, $eB\text{−}\mathrm{\Omega }R$, and $\mu \text{−}\mathrm{\Omega }R$, explored in this work.

The ringdown phase of gravitational waves emitted by a perturbed black hole is described by a superposition of exponentially decaying sinusoidal modes, called quasinormal modes (QNMs), whose frequencies depend only on the property of the black-hole geometry. The extraction of QNM frequencies of an isolated black hole would allow for testing how well the black hole is described by general relativity. However, astrophysical black holes are not isolated. It remains unclear whether the extra matter surrounding the black holes such as accretion disks would affect the validity of the black-hole spectroscopy when the gravitational effects of the disks are taken into account. In this paper, we study the QNMs of a Schwarzschild black hole superposed with a gravitating thin disk. Considering up to the first order of the mass ratio between the disk and the black hole, we find that the existence of the disk would decrease the oscillating frequency and the decay rate. In addition, within the parameter space where the disk model can be regarded as physical, there seems to be a universal relation that the QNM frequencies tend to obey. The relation, if it holds generically, would assist in disentangling the QNM shifts caused by the disk contributions from those induced by other putative effects beyond general relativity. The QNMs in the eikonal limit, as well as their correspondence with bound photon orbits in this model, are briefly discussed.

The current LIGO-Virgo observing run has been pushing the sensitivity limit to touch the stochastic gravitational-wave backgrounds (SGWBs). However, no significant detection has been reported to date for any single dominated source of SGWBs with a single broken-power-law (BPL) spectrum. Nevertheless, it could equally well escape from existing Bayesian searches from, for example, two comparable dominated sources with two separate BPL spectra (double-peak case) or a single source with its power-law behavior in the spectrum broken twice (doubly broken case). In this paper, we put constraints on these two cases but specifically for the model with cosmological first-order phase transitions from Advanced LIGO-Virgo’s first three observing runs. We found strong negative evidence for the double-peak case and hence place 95% confidential level (CL) upper limits ${\mathrm{\Omega }}_{\mathrm{BPL},1}<5.8\times {10}^{-8}$ and ${\mathrm{\Omega }}_{\mathrm{BPL},2}<4.4\times {10}^{-8}$ on the two BPL spectra amplitudes with respect to the unresolved compact binary coalescence (CBC) amplitude ${\mathrm{\Omega }}_{\mathrm{CBC}}<5.6\times {10}^{-9}$. We further found weak negative evidence for the doubly broken case and hence place 95% CL upper limit ${\mathrm{\Omega }}_{\mathrm{DB}}<1.2\times {10}^{-7}$ on the overall amplitude of the doubly broken spectrum with respect to ${\mathrm{\Omega }}_{\mathrm{CBC}}<6.0\times {10}^{-9}$. In particular, the results from the double-peak case have marginally ruled out the strong super-cooling first-order phase transitions at LIGO-Virgo band.

We investigate the possibility of oscillon formation during the preheating phase of asymmetric inflationary potentials. We analytically establish the existence of oscillonlike solutions for the Klein-Gordon equation for a polynomial potential of the form $V(\varphi )=\frac{1}{2}{\varphi }^2+A{\varphi }^3+B{\varphi }^4$ using the small amplitude analysis, which naturally arises as a Taylor expansion of the $\alpha$-attractor E-model for $\varphi \ll M_{\mathrm{pl}}$ and $\alpha \sim \mathcal{O}(1)$. We perform a detailed numerical analysis to study the formation of nonlinear structures in the $\alpha$-attractor E-model using the publicly available lattice simulation code cosmolattice for parameters in the range ${10}^{-5}\lesssim \alpha \lesssim 5\times {10}^{-4}$. We find the backreaction of the field fluctuations onto the evolution of the homogeneous inflaton condensate to be significant for $\alpha \lesssim 2\times {10}^{-4}$ for which we observe the formation of highly nonlinear structures with average equation of state $w\simeq 0$. These nonlinear structures maybe interpreted as oscillons, providing evidence that they can form during the inflaton oscillations around an asymmetric potential and are found to be present for the entirety of the runtime of our simulations, comprising $\gtrsim 40\%$ of the total energy density.

The postinflationary reheating phase is usually said to be solely governed by the decay of coherently oscillating inflatons into radiation. In this submission, we explore a new avenue towards reheating through the evaporation of primordial black holes (PBHs). After the inflation, if PBHs form, depending on its initial mass, abundance, and inflaton coupling with the radiation, we found two physically distinct possibilities of reheating the Universe. In one possibility, the thermal bath is solely obtained from the decay of PBHs while inflaton plays the role of the dominant energy component in the entire process. In the other possibility, we found that PBHs dominate the total energy budget of the Universe during the course of evolution, and then its subsequent evaporation leads to a radiation dominated universe. Furthermore, we analyze the impact of both monochromatic and extended PBH mass functions and estimate the detailed parameter ranges for which those distinct reheating histories are realized.

The impact of light scalars coupled conformally and disformally to matter on the geodetic and frame-dragging precessions is calculated. For larger frequencies the disformal interaction becomes increasingly relevant. We use several satellite experiments and pulsar time of arrival measurements to derive bounds on the couplings, combining the Gravity Probe B, LARES, LAGEOS and GRACE results with pulsar timings. Forecasts for future constraints on the conformal and the disformal couplings based on the GINGER experiment, i.e. a future measurement of the Sagnac effect on Earth, the motion of $S$ stars around the Galactic Center and future pulsar timing observations are presented.

A traveling wave parametric amplifier has been integrated in the haloscope of the QUAX experiment. A search for dark matter axions has been performed with a high-$Q$ dielectric cavity immersed in an 8 T magnetic field and read by a detection chain having a system noise temperature of about 2.1 K at the frequency of 10.353 GHz. Scanning has been conducted by varying the cavity frequency using sapphire rods immersed into the cavity. At multiple operating frequencies, the sensitivity of the instrument was at the level of viable axion models.

We present a new family of exact vacuum solutions to Pfeifer and Wohlfarth’s field equation in Finsler gravity, consisting of Finsler metrics that are Landsbergian but not Berwaldian, also known as unicorns due to their rarity. Interestingly, we find that these solutions have a physically viable light cone structure, even though in some cases the signature is not Lorentzian but positive definite. We furthermore find a promising analogy between our solutions and classical Friedmann-Lemaître-Robertson-Walker cosmology. One of our solutions, in particular, has cosmological symmetry, i.e., it is spatially homogeneous and isotropic, and it is additionally conformally flat, with the conformal factor depending only on the timelike coordinate. We show that this conformal factor can be interpreted as the scale factor, we compute it as a function of cosmological time, and we show that it corresponds to a linearly expanding (or contracting) Finsler universe.

The Mathisson-Papapetrou-Dixon equations describe the motion of spinning test particles in the pole-dipole approximation. It is well known that these equations, which couple the Riemann curvature tensor with the antisymmetric spin tensor $S^{\alpha \beta }$, together with the normalization condition for the four-velocity, is a system of 11 equations relating 14 unknowns. To “close” the system, it is necessary to introduce a constraint of the form $V_{\mu }{S}^{\mu \nu }=0$, usually known as the spin supplementary condition (SSC), where $V_{\mu }$ is a future-oriented reference vector satisfying the normalization condition $V_{\alpha }{V}^{\alpha }=-1$. There are several SSCs in the literature. In particular, the Tulczyjew-Dixon, Mathisson-Pirani, and Ohashi-Kyrian-Semerák are the most used by the community. From the physical point of view, choosing a different SSC (a different reference vector $V^{\mu }$) is equivalent to fixing the centroid of the test particle. In this manuscript, we compare different SSCs for spinning test particles moving around a Morris-Thorne traversable wormhole. To do so, we first obtain the orbital frequency and expand it up to third order in the particle’s spin; as expected, the zero order coincides with the Keplerian frequency, the same in all SSCs; nevertheless, we found that differences appear in the second order of the expansion, similar to the Schwarzschild and Kerr black holes. We also compare the behavior of the innermost stable circular orbit (ISCO). Since each SSC is associated with a different centroid of the test particle, we analyze (separately) the radial and spin corrections for each SSC. We found that the radial corrections improve the convergence, especially between Tulczyjew-Dixon and Mathisson-Pirani SSCs. In the case of Ohashi-Kyrian-Semerák, we found that the spin corrections remove the divergence for the ISCO and extend its existence for higher values of the particle’s spin.

The difficulty in describing the equation of state (EOS) for nuclear matter at densities above the saturation density (${\rho }_0$) has led to the emergence of a multitude of models based on different assumptions and techniques. These equations of state, when used to describe a neutron star (NS), lead to differing values of observables. An outstanding goal in astrophysics is to constrain the dense matter EOS by exploiting astrophysical and gravitational wave measurements. Nuclear matter parameters appear as Taylor coefficients in the expansion of the EOS around the saturation density of symmetric and asymmetric nuclear matter and provide a physically motivated representation of the EOS. In this paper, we introduce a deep learning-based methodology to predict key neutron stars observables such as the NS mass, NS radius, and tidal deformability from a set of nuclear matter parameters. Using generated mock data, we confirm that the neural network model is able to accurately capture the underlying physics of finite nuclei and replicate intercorrelations between the symmetry energy slope, its curvature, and the tidal deformability arising from a set of physical constraints. We also test our network with mock data generated by a different class of physics model, which was not part of the training, to explore the limitations of model dependency in the results. We also study the validity of our trained model using Bayesian inference and show that the performance of our model is on par with physics-based models with the added benefit of much lower computational cost.

We have computed the charge and heat transport coefficients of hot QCD matter by solving the relativistic Boltzmann transport equation using the Bhatnagar-Gross-Krook (BGK) model approximation with a modified collision integral in the weak magnetic-field regime. This modified collision integral enhances both charge and heat transport phenomena which can be understood by the large values of the above-mentioned coefficients in comparison to the relaxation collision integral. We have also presented a comparative study of coefficients like the electrical conductivity (${\sigma }_{el}$), Hall conductivity (${\sigma }_H$), thermal conductivity ($\kappa$), and Hall-type thermal conductivity (${\kappa }_H$) in weak and strong magnetic fields in the BGK model approximation. The effects of weak magnetic field and finite chemical potential on the transport coefficients have been explored using a quasiparticle model. Moreover, we have also studied the effects of weak magnetic field and finite chemical potential on the Lorenz number, Knudsen number, specific heat, elliptic flow, and Wiedemann-Franz law.

Axionlike particles (ALPs) appear in several dark sector studies. They have gained increasing attention from the theoretical and experimental community. In this work, we propose the first search for ALPs to be conducted at the Brazilian Synchrotron Light Laboratory (LNLS). In this work, we derive the projected sensitivity of a proposed experiment for the production of ALPs via the channel $e^{+}{e}^{-}\to a\gamma$. We show that such an experiment could probe ALP masses between 1–55 MeV, and ALP-electron couplings down to $g_{aee}=2–6\times {10}^{-4}{\mathrm{GeV}}^{-1}$ depending on the energy beam, thickness of the target, and background assumptions. Therefore, this quest would cover an unexplored region of parameter space for experiments of this kind, constitute a promising probe for dark sectors, and potentially become the first Latin-American dark sector detector.

We compute the standard Euclidean window of the hadronic vacuum polarization using multiple independent blinded analyses. We improve the continuum and infinite-volume extrapolations of the dominant quark-connected light-quark isospin-symmetric contribution and address additional subleading systematic effects from sea-charm quarks and residual chiral-symmetry breaking from first principles. We find $a_{\mathrm{\mu }}^{\mathrm{W}}=235.56(65)(50)\times {10}^{-10}$, which is in $3.8\sigma$ tension with the recently published dispersive result of $a_{\mathrm{\mu }}^{\mathrm{W}}=229.4(1.4)\times {10}^{-10}$ [G. Colangelo, A. X. El-Khadra, M. Hoferichter, A. Keshavarzi, C. Lehner, P. Stoffer, and T. Teubner, Phys. Lett. B 833, 137313 (2022)] and in agreement with other recent lattice determinations. We also provide a result for the standard short-distance window. The results reported here are unchanged compared to our presentation at the Edinburgh workshop of the g-2 Theory Initiative in 2022 [C. Lehner, Talk Presented at the 5th Plenary Meeting of the g-2 Theory Initiative in Edinburgh (2022)].