We propose to test the light sterile neutrino solution to the Liquid Scintillator Neutrino Detector (LSND) and MiniBooNE anomalies by measuring the coherent elastic scattering rate of neutrinos from a pulsed spallation source. Coherent scattering is universal across all active neutrino flavors, and thus can provide a measurement of the total Standard Model neutrino flux. By performing measurements over different baselines and making use of timing information, it is possible to significantly reduce the systematic uncertainties and to independently measure the fluxes of neutrinos that originate as ${\nu }_{\mu }$ or as either ${\nu }_e$ or ${\overline{\nu }}_{\mu }$. We find that a 100 kg CsI detector would be sensitive to a large fraction of the sterile neutrino parameter space that could potentially account for the LSND and MiniBooNE anomalies.

We analyze the signal sensitivity of multilepton final states at colliders that can arise from doubly and singly charged Higgs decay in a type-II seesaw framework. We assume the triplet vacuum expectation value to be very small and degenerate masses for both the charged Higgs states. The leptonic branching ratios of doubly and singly charged Higgs states have a large dependency on the neutrino oscillation parameters and the lightest neutrino mass scale, as well as the neutrino mass hierarchy. We explore this, as well as the relation between the leptonic branching ratios of the singly and doubly charged Higgs states, in detail. We evaluate the effect of these uncertainties on the production cross section of the multilepton signal. Finally, we present a detailed analysis of multilepton final states for a future hadron collider, HE-LHC, that can operate with center-of-mass energy $\sqrt{s}=27\mathrm{TeV}$.

The tripletlike QED processes $\gamma +{\ell }_i\to {\ell }_j^{+}{\ell }_j^{-}+{\ell }_i$ with $i\ne j$ and $i=e$, $\mu$, $j=e$, $\mu$, $\tau$ has been investigated as the reactions where a dark photon $A^{\prime }$ is produced as a virtual state with a subsequent decay into a ${\ell }_j^{+}{\ell }_j^{-}$ pair. This effect arises due to the so-called kinetic mixing and is characterized by a small parameter $\epsilon$ describing the coupling strength relative to the electric charge $e$. In these processes, the dark photon appears as a resonance with a Breit-Wigner propagator in the ${\ell }_j^{+}{\ell }_j^{-}$ system. The distributions over the invariant mass of the produced ${\ell }_j^{+}{\ell }_j^{-}$ pair are calculated, and the value of the parameter $\epsilon$, as a function of the dark photon mass, is estimated for a given number of measured events in the specific experimental conditions. Assuming a standard deviation of $\sigma =2$ (corresponding to $\approx 95\%$ confidence limit) and a number of measured events equal to ${10}^4$, we obtain the following limits for the parameter space of the dark photon: ${\epsilon }^2\le {10}^{-7}$ ($\gamma +{\mu }^{-}\to e^{+}+e^{-}+{\mu }^{-}$) and ${\epsilon }^2\le {10}^{-7}÷6\times {10}^{-8}$ ($\gamma +e^{-}\to {\mu }^{+}+{\mu }^{-}+e^{-}$) in the $A^{\prime }$ mass region $520<m_{A^{\prime }}<980\mathrm{MeV}$. In the mass region $30<M_{A^{\prime }}<400\mathrm{MeV}$, we obtain ${\epsilon }^2\le {10}^{-7}$ ($\gamma +{\mu }^{-}\to e^{+}+e^{-}+{\mu }^{-}$).

In view of the expectation that the existence of complex poles is a signal of confinement, we investigate the analytic structure of the gluon, quark, and ghost propagators in the Landau gauge QCD and QCD-like theories by employing an effective model with a gluon mass term of the Yang-Mills theory, which we call the massive Yang-Mills model. In this model, we particularly investigate the number of complex poles in the parameter space of the model consisting of gauge coupling constant, gluon mass, and quark mass for the gauge group $SU(3)$ and various numbers of quark flavors $N_F$ within the asymptotic free region. Both the gluon and quark propagators at the best-fit parameters for $N_F=2$ QCD have one pair of complex conjugate poles, while the number of complex poles in the gluon propagator varies between zero and four depending on the number of quark flavors and quark mass. Moreover, as a general feature, we argue that the gluon spectral function of this model with nonzero quark mass is negative in the infrared limit. In sharp contrast to gluons, the quark and ghost propagators are insensitive to the number of quark flavors within the current approximations adopted in this paper. These results suggest that details of the confinement mechanism may depend on the number of quark flavors and quark mass.

We present and develop a general dispersive framework allowing us to construct representations of the amplitudes for the processes $P\pi \to \pi \pi$, $P=K$, $\eta$, valid at the two-loop level in the low-energy expansion. The construction proceeds through a two-step iteration, starting from the tree-level amplitudes and their $S$ and $P$ partial-wave projections. The one-loop amplitudes are obtained for all possible configurations of pion masses. The second iteration is presented in detail in the cases where either all masses of charged and neutral pions are equal or for the decay into three neutral pions. Issues related to analyticity properties of the amplitudes and of their lowest partial-wave projections are given particular attention. This study is introduced by a brief survey of the situation, for both experimental and theoretical aspects, of the decay modes into three pions of charged and neutral kaons and of the eta meson.

In this work we consider the QCD parton saturation models to describe soft interactions at the high energy limit. The total and elastic cross sections, as well as the elastic slope parameter, are obtained for proton-proton and pion-proton collisions and compared to recent experimental results. The analyses are done within the color dipole formalism, taking into account saturation models which have been tested against deep inelastic scattering data. The main point is that the matching between soft and hard interaction occurs in the saturation region which can be described by high density QCD approaches. Discussion is performed on the main theoretical uncertainties associated with calculations.

We investigate the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c{\pi }^{-}{f}_0(980)$ production with a $f_0(980)$ decay into ${\pi }^{+}{\pi }^{-}$ via the $K^{*0}{K}^{-}{K}^{+}$ and $K^{*-}{K}^0{\overline{K}}^0$ triangle loops. These loops produce a peak around 1.42 GeV in the ${\pi }^{-}{f}_0(980)$ invariant mass distribution, which is the same mechanism as the one considered to explain the $a_1(1420)$ peak. In the ${\pi }^{+}{\pi }^{-}$ distribution obtained by fixing the ${\pi }^{-}{f}_0(980)$ invariant mass to some values, a clear peak of $f_0(980)$ is seen, and the ${\pi }^{-}{f}_0(980)$ distribution has a peak around $M_{{\pi }^{-}{f}_0}=1.42\mathrm{GeV}$, which is caused by the triangle mechanism of the $K^{*}\overline{K}K$ loop. The branching ratio of ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c{\pi }^{-}{f}_0(980)$ with $f_0(980)\to {\pi }^{+}{\pi }^{-}$ by the triangle mechanism, obtained by integrating the ${\pi }^{-}{f}_0(980)$ distribution from 1 to 1.6 GeV, is estimated to be the order ${10}^{-4}$. Future measurements of the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c{\pi }^{-}{f}_0(980)$ branching ratio and the ${\pi }^{-}{f}_0(980)$ invariant mass distribution predicted in this work would give further clues to clarify the nature of the $a_1(1420)$ peak.

Despite great agreement with experiment, the Standard Model (SM) of particle physics lacks a viable dark matter (DM) candidate and sufficient amount of $CP$ violation to account for the observed baryon excess in the universe. Nonminimal Higgs frameworks are economic extensions of the SM which could remedy these shortcomings. Within the framework of a three Higgs doublet model, we introduce an extended dark sector which accommodates both DM and $CP$ violation. Such dark sources of $CP$ violation do not contribute to the electric dipole moments and are therefore unconstrained. We present a novel mechanism in which the $CP$-violating dark particles only interact with the SM through the gauge bosons, primarily the $Z$ boson. Such $Z$-portal dark $CP$ violation is realized in the regions of the parameter space where Higgs-mediated (co)annihilation processes are subdominant and have negligible contributions to the DM relic density. We show that such $Z$-portal $CP$-violating DM can still thermalize and satisfy all experimental and observational bounds and discuss the implications of such phenomena for electroweak baryogenesis.

We highlight the principal results of a computation [1] in the color glass condensate effective field theory of the next-to-leading order (NLO) impact factor for inclusive $\mathrm{photon}+\mathrm{dijet}$ production at Bjorken $x_{\text{Bj}}\ll 1$ in deeply inelastic electron-nucleus ($\mathrm{e}+\mathrm{A}\text{DIS}$) collisions. When combined with extant results for next-to-leading log $x_{\text{Bj}}$ JIMWLK renormalization group (RG) evolution of gauge invariant two-point (“dipole”) and four-point (“quadrupole”) correlators of lightlike Wilson lines, the inclusive $\mathrm{photon}+\mathrm{dijet}$ $\mathrm{e}+\text{A DIS cross section can be determined}$ to $\sim 10\%$ accuracy. Our computation simultaneously provides the ingredients to compute fully inclusive DIS, inclusive photon, inclusive dijet, and inclusive $\mathrm{photon}+\text{jet}$ channels to the same accuracy. This makes feasible quantitative extraction of many-body correlators of saturated gluons and precise determination of the saturation scale $Q_{S,A}(x_{\text{Bj}})$ at a future Electron-Ion Collider. An interesting feature of our NLO result is the structure of the violation of the soft gluon theorem in the Regge limit. Another is the appearance in gluon emission of timelike nonglobal logs which also satisfy JIMWLK RG evolution.

Horndeski gravity was highly constrained from the recent gravitational wave observations by the LIGO Collaboration down to $|c_g/c-1|\gtrsim {10}^{-15}$. In this paper, we study the propagation of gravitational waves in a recently proposed model of Horndeski gravity in which its teleparallel gravity analog is formulated. As usually done in these analyses, we consider a flat cosmological background in which curvature is replaced by torsion as the expression of gravitation. It is found that in this approach, one can construct a more general Horndeski theory satisfying $c_T=c_g/c=1$ without eliminating the coupling functions $G_5(\varphi ,X)$ and $G_4(\varphi ,X)$ that were highly constrained in standard Horndeski theory. Hence, in the teleparallel approach one is able to restore these terms, creating an interesting way to revive Horndeski gravity. In this way, we retain the original spirit of Horndeski gravity (unlike beyond Horndeski theories) while only changing the form in which the geometry of gravitation is expressed.

In this paper we study the recently proposed $f(R,\mathcal{L})$ theories from a thermodynamic point of view. The uniqueness of these theories lies in the fact that the space-time curvature is coupled to the baryonic matter instead of exotic matter (in the form of scalar field). We investigate the viability of these theories from the point of view of the thermodynamic stability of the models. To be more precise here we are concerned with the thermodynamics of the apparent horizon of Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime in the background of the $f(R,\mathcal{L})$ theory. We consider several models of $f(R,\mathcal{L})$ theories where both minimal and nonminimal coupling has been considered. Various thermodynamic quantities like entropy, enthalpy, internal energy, Gibbs free energy, etc. are computed and using their allowed ranges various model parameters are constrained.

We consider binary black holes (BBHs) in a hierarchical triple system where a more compact, less-massive binary is emitting detectable gravitational waves (GWs), and the tertiary is a supermassive BH at the center of a nuclear star cluster. As previous works have shown, the orbital motion of the outer binary can generate a detectable relativistic Doppler boost of the GWs emitted by the orbiting inner binary. We show here that, for outer-binary orbits with a period of order one year, there can be a non-negligible probability for repeated gravitational lensing of the GWs emitted by the inner binary. Repeating gravitational lensing events could be detected by the LISA observatory as periodic GW amplitude spikes before the BBH enters the LIGO band. Such a detection would confirm the origin of some BBH mergers in nuclear star clusters. GW lensing also offers new testing grounds for strong gravity.

We study pentaquark states of both light $q^4\overline{q}$ and hidden heavy $q^{3}Q\overline{Q}$ ($\mathrm{q}=\mathrm{u},\mathrm{d},\mathrm{s}$ quark in SU(3) flavor symmetry; $\mathrm{Q}=\mathrm{c}$, b quark) systems with a general group theory approach in the constituent quark model, and the spectrum of light baryon resonances in the ansatz that the $l=1$ baryon states may consist of the $q^3$ as well as $q^4\overline{q}$ pentaquark component. The model is fitted to ground state baryons and light baryon resonances which are believed to be normal three-quark states. The work reveals that the $N(1535)1/2^{-}$ and $N(1520)3/2^{-}$ may consist of a large $q^4\overline{q}$ component while the $N(1895)1/2^{-}$ and $N(1875)3/2^{-}$ are respectively their partners, and the $N^{+}(1685)$ might be a $q^4\overline{q}$ state. By the way, a new set of color-spin-flavor-spatial wave function for $q^{3}Q\overline{Q}$ systems in the compact pentaquark picture are constructed systematically for studying hidden charm pentaquark states.

At the Large Hadron Collider (LHC), several far detectors such as FASER and MATHUSLA have been proposed to target the long-lived particles (LLPs) featured with displaced vertices. Naturally one question arises as to the feasibility of installing similar far detectors at future lepton colliders like the CEPC and FCC-ee. Because of the different kinematics of final state particles and the freedom to locate both the experiment hall and the detectors, the future lepton collider with an additional far detector may play a unique role in searching for LLPs. In this study, we consider various locations and designs of far detectors at future $e^{-}{e}^{+}$ colliders and investigate their potentials for discovering LLPs in the physics scenarios including exotic Higgs decays, heavy neutral leptons, and the lightest neutralinos. Our analyses show that the kinematical distinctions between the lepton and hadron colliders render the optimal positions of far detectors lying at the direction perpendicular to the collider beams at future $e^{-}{e}^{+}$ colliders, in contrast to the LHC where a boost in the forward direction can be exploited. We also find that when searching for LLPs, such new experiments with far detectors at future lepton colliders may extend and complement the sensitivity reaches of the experiments at the future lepton colliders with usual near detectors, and the present and future experiments at the LHC. In particular, we find that, for the theory models considered in this study, a MATHUSLA-sized far detector would give a modest improvement compared to the case with a near detector only at future lepton colliders.

Using soft collinear effective field theory, we derive the factorization theorem for the quasi-transverse-momentum-dependent (quasi-TMD) operator. We check the factorization theorem at one-loop level and compute the corresponding coefficient function and anomalous dimensions. The factorized expression is built from the physical TMD distribution, and a nonperturbative lattice related factor. We demonstrate that lattice related functions cancel in appropriately constructed ratios. These ratios could be used to explore various properties of TMD distributions, for instance, the nonperturbative evolution kernel. A discussion of such ratios and the related continuum properties of TMDs is presented.

In this work we analyze the entanglement entropy in deep inelastic scattering off protons and nuclei. It is computed based on the formalism where the partonic state at small-$x$ is maximally entangled with proton being constituted by large number of microstates occurring with equal probabilities. We consider analytical expressions for the number of gluons, $N_{\text{gluon}}$, obtained from gluon saturation models for the dipole-target amplitudes within the QCD color dipole picture. In particular, the nuclear entanglement entropy per nucleon is studied. We also study the underlying uncertainties on these calculations and compare the results to similar investigations in literature.

We study the chiral phase transition of the two-flavor Nambu-Jona-Lasinio (NJL) model in a rotating sphere, which includes both rotation and finite size effects. We find that rotation leads to a suppression of the chiral condensate at a finite temperature, while its effects are smaller than the finite size effects. Our work can be helpful to study the effects relevant to rotation in heavy-ion collisions in a more realistic way.

Applying the vacuum-to-$B$-meson correlation functions with an interpolating current for the light vector meson we construct the light-cone sum rules (LCSR) for the “effective” form factors ${\xi }_{\parallel }(n·p)$, ${\xi }_{\perp }(n·p)$, ${\mathrm{\Xi }}_{\parallel }(\tau ,n·p)$ and ${\mathrm{\Xi }}_{\perp }(\tau ,n·p)$, defined by the corresponding hadronic matrix elements in soft-collinear effective theory (SCET), entering the leading-power factorization formulas for QCD form factors responsible for $B\to V\ell {\overline{\nu }}_{\ell }$ and $B\to V\ell \overline{\ell }$ decays at large hadronic recoil at next-to-leading-order in QCD. The evanescent-operator approach for the perturbative matching of the effective operators from ${\mathrm{SCET}}_{\mathrm{I}}\to \mathrm{HQET}$ is employed in the determination of the hard-collinear functions entering the SCET factorization formulas for the vacuum-to-$B$-meson correlation functions. The light-quark mass effect for the local SCET form factors ${\xi }_{\parallel }(n·p)$ and ${\xi }_{\perp }(n·p)$ is also computed from the LCSR method with the $B$-meson light-cone distribution amplitude ${\varphi }_B^{+}(\omega ,\mu )$ at $\mathcal{O}({\alpha }_s)$. Furthermore, the subleading power corrections to $B\to V$ form factors from the higher-twist $B$-meson light-cone distribution amplitudes are also computed with the same method at tree level up to the twist-six accuracy. Employing the two different models for the $B$-meson light-cone distribution amplitudes consistent with QCD equations of motion, we observe that the higher-twist corrections to $B\to V$ form factors are dominated by the two-particle twist-five distribution amplitude $g_B^{-}(\omega ,\mu )$, in analogy to the previous observation for $B\to P$ form factors. Having at our disposal the LCSR predictions for $B\to V$ form factors, we further perform new determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{ub}|$ from the semileptonic $B\to \rho \ell {\overline{\nu }}_{\ell }$ and $B\to \omega \ell {\overline{\nu }}_{\ell }$ decays, and predict the normalized differential branching fractions and the $q^2$-binned $K^{*}$ longitudinal polarization fractions of the exclusive rare $B\to K^{*}{\nu }_{\ell }{\overline{\nu }}_{\ell }$ decays.

A phenomenological model for the description of the single and double diffractive excitation in $pp$ collisions at high energies is presented. Considering the Good-Walker approach, we propose a model for the eigenstates of the scattering operator and for the treatment of the interaction between them, with the high energy behavior of the cross section driven by perturbative QCD. The behavior of the total, elastic, single, and double diffractive cross sections are analyzed and predictions for the energies of Run 3 of the LHC and those of the cosmic rays experiments are derived. We demonstrate that the model describes the current data for the energy dependence of the cross sections. A comparison with the recent data for the $\rho$ parameter and the differential elastic cross section are also presented and shortcomings of the current model are discussed.

We calculate the neutral pion mass in the presence of an external magnetic field of arbitrary strength in the framework of the linear sigma model coupled to quarks at zero temperature. We find nonmonotonic behavior of the pion mass as a function of magnetic field. We are also able to reproduce existing results for the weak-field approximation.