Stimulated by the measurement of the $J\psi \varphi$ decay model of $Y(4274)$ by the LHCb Collaboration, we consider a possible interpretation of this state as a hadron molecular-a bound state of $D_s$ and ${\overline{D}}_{s0}(2317)$ mesons. Using effective Lagrangian approach, we calculate the two-body strong decay channels $Y(4274)\to J/\psi \varphi ,{\chi }_{c0}\eta ,{\chi }_{c0}\eta ,D_s^{*}{\overline{D}}_s$, $D{\overline{D}}^{*}$, $K{\overline{K}}^{*}$, and $\varphi \varphi$ through hadronic loops and three-body decays into ${\pi }^0{D}_s{\overline{D}}_s$. In comparison with the LHCb data, our results show that $Y(4274)$ cannot be assigned to be a $D_s{\overline{D}}_{s0}(2317)$ molecular state. The calculated partial decay widths with the $J^P=1^{+}$ $D_s{\overline{D}}_{s0}$ molecular state picture indicate that allowed decay modes ${\chi }_{c0}\eta$ and ${\chi }_{c1}\eta$ may have the smallest branching ratio and are of the order of 0.0 MeV. Future experimental measurements of such two processes can be quite useful to test the different interpretations of the $Y(4274)$. If $P$-wave $D_s{\overline{D}}_{s0}$ molecular exists [marked as $Y^{\prime }(4274)$], the total decay is at the order of 1.06–1.84 MeV, which seems to be within the reach of the current experiments such as Belle II. In addition, the calculated partial decay widths indicate that allowed decay mode $D{\overline{D}}^{*}$ may have the biggest branching ratio. The experimental measurements for this strong decay process could be a crucial to observe such a new state $Y^{\prime }(4274)$.

Long-lived particles that are present in many new physics models beyond the standard model, can be searched for in a number of newly proposed lifetime frontier experiments at the LHC. The signals of the long-lived dark photons can be significantly enhanced in a new dark photon model in which dark photons are copiously produced in the hidden radiation process. We investigate the capability of various lifetime frontier detectors in probing the parameter space of this model, including the far forward detectors FACET and FASER, the far transverse detector MATHUSLA, and the precision timing detector CMS-MTD. We find that the accessible parameter space is significantly enlarged by the hidden radiation process so that FACET, MATHUSLA, and CMS-MTD can probe a much larger parameter space than the so-called minimal model. The parameter space probed by FACET is found to be much larger than FASER, which is largely due to the fact that the former has a larger decay volume and is closer to the interaction point. There also exists some parameter space that can be probed both by the far detectors and by precision timing detectors, so that different experiments can be complementary to each other. A brief overview of the lifetime frontier detectors is also given.

We numerically study the phase structure of the $CP(1)$ model in the presence of a topological $\theta$-term, a regime afflicted by the sign problem for conventional lattice Monte Carlo simulations. Using a bond-weighted tensor renormalization group method, we compute the free energy for inverse couplings ranging from $0\le \beta \le 1.1$ and find a $CP$-violating, first-order phase transition at $\theta =\pi$. In contrast to previous findings, our numerical results provide no evidence for a critical coupling ${\beta }_c<1.1$ above which a second-order phase transition emerges at $\theta =\pi$ and/or the first-order transition line bifurcates at $\theta \ne \pi$. If such a critical coupling exists, as suggested by Haldane’s conjecture, our study indicates that is larger than ${\beta }_c>1.1$.

We study the renormalization group (RG) running of the quark mass, for $N_f=3$ QCD with Wilson fermions in a mixed action setup, with standard Schrödinger functional (SF) boundary conditions for sea quarks and chirally rotated Schrödinger functional ($\chi \mathrm{SF}$) boundary conditions for valence quarks. This necessitates the tuning of the boundary factor $z_{\mathrm{f}}(g_0^2)$ of the $\chi \mathrm{SF}$ valence action, in order to ensure that QCD symmetries are fully recovered in the continuum. The properties of this novel setup are monitored through the ratios $Z_S/Z_P$ and ${\mathrm{\Sigma }}_S/{\mathrm{\Sigma }}_P$ of the renormalization parameters and step scaling functions of the scalar and pseudoscalar densities. Where comparison is possible, our $Z_S/Z_P$ results are found to agree with previous determinations, based on a mass ratio method [G. M. de Divitiis et al. (ALPHA Collaboration), Eur. Phys. J. C 79, 797 (2019)] and Ward identities [ J. Heitger et al. (ALPHA Collaboration), Eur. Phys. J. C 80, 765 (2020); J. Heitger et al., Eur. Phys. J. C 81, 606 (2021)], with Schrödinger functional boundary conditions. The behavior of ${\mathrm{\Sigma }}_S/{\mathrm{\Sigma }}_P$ confirms the theoretical expectations of $\chi \mathrm{SF}$ QCD, related to the restoration of the theory’s symmetries in the continuum limit. From the step-scaling function of the pseudoscalar density we obtain the quark mass RG-running function from hadronic to perturbative energy scales. This is fully compatible with the earlier result obtained in a similar setup for Wilson quarks with Schrödinger functional boundary conditions [I. Campos et al., Eur. Phys. J. C 78, 387 (2018)], and provides a strong universality test for the two lattice setups.

We calculate the electric conductivity $\sigma$ in deconfined QCD matter using a holographic QCD model, i.e., the Sakai-Sugimoto model with varying magnetic field $B$ and chiral anomaly strength. After confirming that our estimated $\sigma$ for $B=0$ is consistent with the lattice-QCD results, we study the case with $B\ne 0$ in which the coefficient $\alpha$ in the Chern-Simons term controls the chiral anomaly strength. Our results imply that the transverse conductivity ${\sigma }_{\perp }$ is suppressed to be $\lesssim 70\%$ at $B\sim 1{\mathrm{GeV}}^2$ as compared to the $B=0$ case when the temperature is fixed as $T=0.2\mathrm{GeV}$. Since the Sakai-Sugimoto model has massless fermions, the longitudinal conductivity ${\sigma }_{\parallel }$ with $B\ne 0$ should diverge due to production of the matter chirality. Yet, it is possible to extract a regulated part out from ${\sigma }_{\parallel }$ with an extra condition to neutralize the matter chirality. This regulated quantity is interpreted as an Ohmic part of ${\sigma }_{\parallel }$. We show that the longitudinal Ohmic conductivity increases with increasing $B$ for small $\alpha$, while it is suppressed with larger $B$ for physical $\alpha =3/4$ due to anomaly-induced interactions.

Inspired by the $T_{cc}^{+}$ signal discovered by the LHCb Collaboration, we systematically investigate the doubly heavy tetraquark states with the molecule configuration $[Q_1{\overline{q}}_2{]}_{{\mathbf{1}}_c}[Q_3{\overline{q}}_4{]}_{{\mathbf{1}}_c}$ ($Q=c$ and $b$, $q=u$, $d$, and $s$) in a nonrelativistic quark model. The model involves a color screening confinement potential, meson-exchange interactions, and one-gluon-exchange interactions. The state $T_{cc}^{+}$ with $I{J}^P=01^{+}$ is a very loosely bound deuteronlike state with a binding energy around 0.34 MeV and a huge size of 4.32 fm. Both the meson exchange force and the coupled channel effect play a pivotal role. Without the meson exchange force, there does not exist the $T_{cc}^{+}$ molecular state. In strong contrast, the QCD valence bond forms clearly in the $T_{bb}^{-}$ system when we turn off the meson-exchange force, which is very similar to the hydrogen molecule in QED. Moreover, the $T_{bb}^{-}$ becomes a heliumlike QCD-atom if we increase the bottom quark mass by a factor of three. Especially, the states $T_{bb}^{-}$ with ${01}^{+}$, $T_{bc}^0$ with ${00}^{+}$ and ${01}^{+}$, and the $V$-spin antisymmetric states $T_{bbs}^{-}$ with $\frac{1}{2}{1}^{+}$, $T_{bcs}^0$ with $\frac{1}{2}{0}^{+}$ and $\frac{1}{2}{1}^{+}$ can form a compact, hydrogen moleculelike or deuteronlike bound state with different binding dynamics. The high-spin states $T_{bc}^0$ with ${02}^{+}$ and $T_{bcs}^0$ with $\frac{1}{2}{2}^{+}$ can decay into $D$-wave $\overline{B}D$ and ${\overline{B}}_{s}D$ although they are below the thresholds ${\overline{B}}^{*}{D}^{*}$ and ${\overline{B}}_s^{*}{D}^{*}$, respectively. The isospin and $V$-spin symmetric states are unbound. We also calculate their magnetic moments and axial charges.

One can use more than one scale variable to specify the family of surfaces in the space of parton splitting parameters that define the evolution of a parton shower. Considering $e^{+}{e}^{-}$ annihilation, we use two variables, with shower evolution following a special path in this two dimensional space. In addition, we treat in a special way the part of the splitting function that has a soft emission singularity but no collinear singularity. This leads to certain advantages compared to the usual shower formulation with only one scale variable.

We extend the effective dynamical quasiparticle model (DQPM)—constructed for the description of nonperturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP)—to large baryon chemical potentials, ${\mu }_B$, including a critical endpoint (CEP) and a first-order phase transition. The DQPM description of quarks and gluons is based on partonic propagators with complex self-energies where the real part of the self-energies is related to the quasiparticle mass and the imaginary part to a finite width of their spectral functions (i.e., the imaginary parts of the propagators). In DQPM the determination of complex self-energies for the partonic degrees of freedom at zero and finite ${\mu }_B$ has been performed by adjusting the entropy density to the lattice QCD data. The temperature-dependent effective coupling (squared) $g^2(T/T_c)$, as well as the effective masses and widths of the partons are based on this adjustments. The novel extended dynamical quasiparticle model, named “DQPM-CP,” makes it possible to describe thermodynamical and transport properties of quarks and gluons in a wide range of temperature, $T$, and baryon chemical potential, ${\mu }_B$, and reproduces the equation of state of lattice QCD calculations in the crossover region of finite $T,{\mu }_B$. We apply a scaling ansatz for the strong coupling constant near the CEP, located at $(T^{\mathrm{CEP}},{\mu }_B^{\mathrm{CEP}})=(0.100,0.960)\mathrm{GeV}$. We show the equation of state as well as the speed of sound for $T>T_c$ and for a wide range of ${\mu }_B$, which can be of interest for hydrodynamical simulations. Furthermore, we consider two settings for the strange quark chemical potentials, (I) ${\mu }_q={\mu }_u={\mu }_s={\mu }_B/3$ and (II) ${\mu }_s=0,{\mu }_u={\mu }_d={\mu }_B/3$. The isentropic trajectories of the quark-gluon plasma matter are compared for these two cases. The phase diagram of DQPM-CP is close to PNJL calculations. The leading order pQCD transport coefficients of both approaches differ. This elucidates that the knowledge of the phase diagram alone is not sufficient to describe the dynamical evolution of strongly interacting matter.

We make a systematic calculation for polarized vector meson production in semi-inclusive lepton-nucleon deep inelastic scattering $e^{-}N\to e^{-}VX$. We consider the general case of neutral current electroweak interactions at high energies which give rise to parity-violating effects. We present a general kinematic analysis for the process and show that the cross sections are expressed by 81 structure functions. We further give a parton model calculation for the process and show the results for the structure functions in terms of the transverse momentum dependent parton distribution functions and fragmentation functions at the leading order and leading twist of perturbative quantum chromodynamics. The results show that there are 27 nonzero structure functions at this order, among which 15 are related to the tensor polarization of the vector meson. Thirteen structure functions are generated by parity-violating effects. We also present the result and a rough numerical estimate for the spin alignment of the vector meson.

We study the charmless two-body decays of $B\to {\mathbf{B}}_n{\overline{\mathbf{B}}}_n^{\prime }$ with $B=(B^{+},B^0,B_s^0)$ and ${\mathbf{B}}_n^{(\prime )}$ the low-lying octet baryons. The factorizable amplitudes are calculated by the modified bag model, while the nonfactorizable ones are extracted from the experimental data with the $SU(3{)}_F$ flavor symmetry. We are able to explain all current experimental measurements and provide predictions on the decay branching ratios in $B\to {\mathbf{B}}_n{\overline{\mathbf{B}}}_n^{\prime }$. Particularly, we find that $\mathcal{B}(B_s^0\to {\mathrm{\Xi }}^0{\overline{\mathrm{\Xi }}}^0)=(32.5\pm 3.7)\times {10}^{-7}$ and $\mathcal{B}(B_s^0\to {\mathrm{\Xi }}^{-}{\overline{\mathrm{\Xi }}}^{-})=(33.1\pm 3.8)\times {10}^{-7}$; these are sizable and able to be observed in the ongoing experiments at LHCb and BELLE-II. Furthermore, the decay branching ratios of $B_s^0\to (p\overline{p},n\overline{n})$ and $B^0\to ({\mathrm{\Xi }}^0{\overline{\mathrm{\Xi }}}^0,{\mathrm{\Sigma }}^{+}{\overline{\mathrm{\Sigma }}}^{+})$ are expected to be $O({10}^{-10})$, which are suppressed due to the angular momentum conservation and chiral symmetry.

We revisit the observable used for the direct measurements of the electron’s $g$ factor. This is done by considering the subleading effects of the large magnetic background field and virtual Standard Model processes. We find substantial corrections to the Landau levels of the electron. Implications for the observed magnetic moment and the tension between direct and indirect measurement are discussed.

We analyze the electroweak interactions in the framework of the Higgs effective field theory using the available Higgs and electroweak diboson production results from LHC run 2 as well as the electroweak precision data. Assuming universality of the weak current, our study considers 25 possible anomalous couplings. To unveil the nature of the Higgs boson, i.e., isosinglet versus part of $SU(2{)}_L$ doublet, we explore the correlation effects between observables that are predicted to exist in the linear realization of the electroweak gauge symmetry but not in its nonlinear counterpart. This improves previous studies aimed at investigating the Higgs nature and the origin of the electroweak symmetry breaking.

In this work, we use reconstruction methods to obtain cosmological solutions in the recently developed scalar-tensor representation of $f(R,T)$ gravity. Assuming that matter is described by an isotropic perfect fluid and the spacetime is homogeneous and isotropic, i.e., the Friedmann-Lemaître-Robertson-Walker (FLRW) universe, the energy density, the pressure, and the scalar field associated with the arbitrary dependency of the action in $T$ can be written generally as functions of the scale factor. We then select three particular forms of the scale factor: an exponential expansion with $a(t)\propto e^t$ (motivated by the de Sitter solution); and two types of power-law expansion with $a(t)\propto t^{1/2}$ and $a(t)\propto t^{2/3}$ (motivated by the behaviors of radiation- and matter-dominated universes in general relativity, respectively). A complete analysis for different curvature parameters $k=\{-1,0,1\}$ and equation of state parameters $w=\{-1,0,1/3\}$ is provided. Finally, the explicit forms of the functions $f(R,T)$ associated with the scalar-field potentials of the representation used are deduced.

A 10% difference in the scale for the Hubble parameter constitutes a clear problem for cosmology. Here, considering angular distribution of type Ia supernovae (SN) within the Pantheon compilation and working within flat $\mathrm{\Lambda }\mathrm{CDM}$ cosmology, we observe a correlation between higher $H_0$ and the CMB dipole direction, confirming our previous results for strongly lensed quasars [Classical Quantum Gravity 38, 184001 (2021)]. Concretely, we record a $\sim 1\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$ variation in $H_0$ at antipodal points on the sky within the Pantheon sample, which is evident in the Low $z$ subsample ($z\lesssim 0.075$) and gets enhanced by higher redshift SN. Our work raises the possibility that we may be at the precision required to probe anisotropic Hubble expansions, while providing a concrete prediction for future inferences of $H_0$.

We examine the potential to probe generalized neutrino interactions (GNIs), exotic effective couplings due to new physics interactions beyond the Standard Model, in the coherent-elastic neutrino-nucleus scattering experiments in light of the latest COHERENT-CsI and -LAr data. Our analysis focuses on scalar-, vector-, and tensor-flavored GNI parameters. A combined analysis has been made to constrain these exotic couplings for the CsI and LAr detector. We further add the projected forthcoming reactor-based scintillating bubble chamber detector to examine these couplings. It has been observed that the addition of reactor data strongly constrained electron flavor GNIs.

The cosmological evolution can modify the dark matter (DM) properties in the early Universe to be vastly different from the properties today. Therefore, the relation between the relic abundance and the DM constraints today needs to be revisited. We propose novel transient annihilations of DM that helps to alleviate the pressure from DM null detection results. As a concrete example, we consider the vector portal DM and focus on the mass evolution of the dark photon. When the Universe cools down, the gauge boson mass can increase monotonically and go across several important thresholds, opening new transient annihilation channels in the early Universe. Those channels are either forbidden or weakened at the late Universe, which helps to evade the indirect searches. In particular, the transient resonant channel can survive direct detection (DD) without tuning the DM to be half of the dark photon mass and can be soon tested by future DD or collider experiments. A feature of the scenario is the existence of a light dark scalar.

We study nonperturbative flavor correlations between pairs of leading and next-to-leading charged hadrons within jets at the Electron-Ion Collider (EIC). We introduce a charge correlation ratio observable $r_c$ that distinguishes same- and opposite-sign charged pairs. Using Monte Carlo simulations with different event generators, $r_c$ is examined as a function of various kinematic variables for different combinations of hadron species, and the feasibility of such measurements at the EIC is demonstrated. The precision hadronization study we propose will provide new tests of hadronization models and hopefully lead to improved quantitative, and perhaps eventually analytic, understanding of nonperturbative QCD dynamics.

Herein, we explore superradiance for Alfvén waves (Alfvénic superradiance) in an axisymmetric rotating magnetosphere of a Kerr black hole within the force-free approximation. On the equatorial plane of the Kerr spacetime, the Alfvén wave equation is reduced to a one-dimensional Schrödinger-type equation by separating variables of the wave function and introducing a tortoise coordinate mapping the inner and outer light surfaces to $-\infty$ and $+\infty$, respectively, and we investigate a wave scattering problem for Alfvén waves. An analysis of the asymptotic solutions of the wave equation and conservation of the Wronskian provides the superradiant condition for Alfvén waves, and it is shown that the condition coincides with that for the Blandford-Znajek process. This indicates that when Alfvénic superradiance occurs, the Blandford-Znajek process also occurs in the force-free magnetosphere. Then, we evaluate the reflection rate of Alfvén waves numerically and confirm that Alfvénic superradiance is indeed possible in the Kerr spacetime. Moreover, we will discuss a resonant scattering of Alfvén waves, which is related to a “quasinormal mode” of the magnetosphere.

We present a novel family of slowly rotating black hole solutions in four, and higher dimensions, that extend the well known Lense-Thirring spacetime and solve the field equations to linear order in rotation parameter. As “exact metrics” in their own right, the new (nonvacuum) spacetimes feature the following two remarkable properties: (i) near the black hole horizon they can be cast in the, manifestly regular, Painlevé-Gullstrand form and (ii) they admit exact Killing tensor symmetries. We show these symmetries are inherited from the principal Killing-Yano tensor of the exact rotating black hole geometry in the slow rotation limit. This provides a missing link as to how the exact hidden symmetries emerge as rotation is switched on. Remarkably, in higher dimensions the novel generalized Lense-Thirring spacetimes feature a rapidly growing number of exact irreducible rank-2, as well as higher-rank, Killing tensors—giving a first example of a physical spacetime with more hidden than explicit symmetries.