This paper explores the effects of finite width in processes of pair production of an extra heavy quark with charge $2/3$ (top partner) and its subsequent decay into a bosonic dark matter (DM) candidate—either scalar or vector—and SM up-type quarks at the Large Hadron Collider (LHC). This dynamics has been ignored so far in standard experimental searches of heavy quarks decaying to DM and we assess herein the regions of validity of current approaches, based on the assumption that the extra quarks have a narrow width. Further, we discuss the configurations of masses, widths and couplings where the latter breaks down.

We study constraints and implications of the recent LHCb measurement of $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$ for tree-level Higgs-mediated flavor-changing neutral current (FCNC) interactions. Combined with experimental data on the $B_s$ mass difference $\mathrm{\Delta }{m}_s$ and the $h\to \mu \tau$ and $h\to {\tau }^{+}{\tau }^{-}$ decay branching ratios from the LHC, we find that the Higgs FCNC couplings are severely constrained. The allowed regions for $B_s\to \mu \tau$, $\tau \tau$ and $h\to sb$ decays are obtained. Current data allow large $CP$ violation in the $h\to {\tau }^{+}{\tau }^{-}$ decay. Consequences of the Cheng-Sher ansatz for the Higgs-Yukawa couplings are discussed in some detail.

Processes with dark matter interacting with the standard model fermions through new scalars or pseudoscalars with flavor-diagonal couplings proportional to fermion mass are well motivated theoretically, and provide a useful phenomenological model with which to interpret experimental results. Two modes of dark matter production from these models have been considered in the existing literature: pairs of dark matter produced through top quark loops with an associated monojet in the event, and pair production of dark matter with pairs of heavy flavored quarks (tops or bottoms). In this paper, we demonstrate that a third, previously overlooked channel yields a non-negligible contribution to LHC dark matter searches in these models. In spite of a generally lower production cross section at LHC when compared to the associated top-pair channel, non-flavor violating single top quark processes are kinematically favored and can significantly increase the sensitivity to these models. Including dark matter production in association with a single top quark through scalar or pseudoscalar mediators, the exclusion limit set by the LHC searches for dark matter can be improved by 30% up to a factor of two, depending on the mass assumed for the mediator particle.

We study the effects of considering nontrivial unphysical lepton sector phases on the group theoretical properties of the flavor and generalized $CP$ symmetry elements in the case where there are three light, distinct Majorana neutrino species. We highlight the similarities and differences between the charged lepton and neutrino sectors and further elucidate the group properties of the flavor and generalized $CP$ symmetry elements. We show how the inclusion of these leptonic phases affects the bottom-up constructions of these symmetry elements and discuss the implications for top-down model building based on discrete symmetry groups.

In general, we can propose the hybrid supersymmetry breakings and hybrid mediations in the supersymmetric standard models. In this paper, we study the hybrid mediation for supersymmetry (SUSY) breaking. In particular, we study how to keep the good properties of gravity mediation, gauge mediation, and anomaly mediation, while solving their problems simultaneously. As an example, we consider the gauge-gravity mediation, where all the supersymmetric particles (sparticles) obtain the SUSY breaking soft terms from the traditional gravity mediation while gauge mediation gives dominant contributions to the soft terms in the colored sector due to the splitted messengers. Thus, we can realize the electroweak supersymmetry naturally where the sleptons, sneutrinos, and electroweakinos are light within one TeV while the squarks and gluino are heavy around a few TeVs. Then we can explain 125 GeV Higgs mass, satisfy the LHC SUSY search bounds, and explain the anomalous magnetic moment of muon, etc. Moreover, the gluino and squarks are well beyond the current LHC run II searches.

It is possible to ameliorate the Higgs vacuum stability problem by switching over to two-Higgs-doublet models (2HDM), ensuring a stable electroweak vacuum up to the Planck scale, even though the top quark mass may be on the high side. However, the simultaneous requirements of perturbative unitarity, and also compatibility with collider and flavor data, constrain the parameter space severely. We investigate the collider signals answering to the regions allowed by such constraints. In particular, the near degeneracy of the neutral heavy scalar and the pseudoscalar is a feature that is probed. The LHC allows distinguishability of these two states, together with signal significance of at least $3\sigma$, in its high-luminosity run. While $e^{+}{e}^{-}$ colliders may have rather low event rates, muon colliders, cashing in on the principle of radiative return, can probe 2HDM scenarios with (pseudo)scalar masses up to TeV or so, though with the price of losing distinction between the $CP$-even and -odd states.

We present a lattice calculation of the masses and decay constants of $D_{(s)}^{*}$ and $B_{(s)}^{*}$ mesons using the gauge configurations produced by the European Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ dynamical quarks at three values of the lattice spacing $a\sim (0.06-0.09)\mathrm{fm}$. Pion masses are simulated in the range $M_{\pi }\simeq (210–450)\mathrm{MeV}$, while the strange and charm sea-quark masses are close to their physical values. We compute the ratios of vector to pseudoscalar masses and decay constants for various values of the heavy-quark mass $m_h$ in the range $0.7m_c^{\mathrm{phys}}\lesssim m_h\lesssim 3m_c^{\mathrm{phys}}$. In order to reach the physical $b$-quark mass, we exploit the heavy quark effective theory prediction that, in the static limit of infinite heavy-quark mass, the considered ratios are equal to one. At the physical point our results are $M_{D^{*}}/M_D=1.0769(79)$, $M_{D_s^{*}}/M_{D_s}=1.0751(56)$, $f_{D^{*}}/f_D=1.078(36)$, $f_{D_s^{*}}/f_{D_s}=1.087(20)$, $M_{B^{*}}/M_B=1.0078(15)$, $M_{B_s^{*}}/M_{B_s}=1.0083(10)$, $f_{B^{*}}/f_B=0.958(22)$ and $f_{B_s^{*}}/f_{B_s}=0.974(10)$. Combining them with the experimental values of the pseudoscalar meson masses (used as input to fix the quark masses) and the values of the pseudoscalar decay constants calculated by ETMC, we get $M_{D^{*}}=2013(14)$, $M_{D_s^{*}}=2116(11)$, $f_{D^{*}}=223.5(8.4)$, $f_{D_s^{*}}=268.8(6.6)$, $M_{B^{*}}=5320.5(7.6)$, $M_{B_s^{*}}=5411.36(5.3)$, $f_{B^{*}}=185.9(7.2)$ and $f_{B_s^{*}}=223.1(5.4)\mathrm{MeV}$.

Using a soft-wall AdS/QCD approach we derive the Schrödinger-type equation of motion for the tetraquark wave function, which is dual to the dimension-4 AdS bulk profile. The latter coincides with the number of constituents in the leading Fock state of the tetraquark. The obtained equation of motion is solved analytically, providing predictions for both the tetraquark wave function and its mass. A low mass limit for possible tetraquark states is given by $M\ge 2\kappa =1\mathrm{GeV}$, where $\kappa =0.5\mathrm{GeV}$ is the typical value of the scale parameter in soft-wall AdS/QCD. We confirm results of the COMPASS Collaboration recently reported on the discovery of the $a_1(1414)$ state, interpreted as a tetraquark state composed of light quarks and having $J^{PC}=1^{++}$. Our prediction for the mass of this state, $M_{a_1}=\sqrt{2}\mathrm{GeV}\simeq 1.414\mathrm{GeV}$, is in good agreement with the COMPASS result $M_{a_1}=1.414_{-0.013}^{+0.015}\mathrm{GeV}$. Next we included finite quark mass effects, which are essential for the tetraquark states involving heavy quarks.

We investigate the symmetry property and the stability of the heptaquark containing two identical heavy antiquarks using color-spin interaction. We construct the wave function of the heptaquark from the Pauli exclusion principle in the SU(3) breaking case. The stability of the heptaquark against the strong decay into one baryon and two mesons is discussed in a simple chromomagnetic model. We find that $q^2{s}^3{\overline{s}}^2$ with $I=0,S=\frac{5}{2}$ is the most stable heptaquark configuration that could be probed by reconstructing the $\mathrm{\Lambda }+\varphi +\varphi$ invariant mass.

We present a novel global QCD analysis of charged $D^{*}$-meson fragmentation functions at next-to-leading order accuracy. This is achieved by making use of the available data for single-inclusive $D^{*}$-meson production in electron-positron annihilation, hadron-hadron collisions, and, for the first time, in-jet fragmentation in proton-proton scattering. It is shown how to include all relevant processes efficiently and without approximations within the Mellin moment technique, specifically for the in-jet fragmentation cross section. The presented technical framework is generic and can be straightforwardly applied to future analyses of fragmentation functions for other hadron species, as soon as more in-jet fragmentation data become available. We choose to work within the zero mass variable flavor number scheme which is applicable for sufficiently high energies and transverse momenta. The obtained optimum set of parton-to-$D^{*}$ fragmentation functions is accompanied by Hessian uncertainty sets which allow one to propagate hadronization uncertainties to other processes of interest.

We present the results of a combined fit of the reactor antineutrino rates and the Daya Bay measurement of ${\sigma }_{f,235}$ and ${\sigma }_{f,239}$. The combined fit leads to a better determination of the two cross sections per fission: ${\sigma }_{f,235}=6.29\pm 0.08$ and ${\sigma }_{f,239}=4.24\pm 0.21$ in units of ${10}^{-43}{\mathrm{cm}}^2/\text{fission}$, with respective uncertainties of about 1.2% and 4.9%. Since the respective deviations from the theoretical cross sections per fission are $2.5\sigma$ and $0.7\sigma$, we conclude that, if the reactor antineutrino anomaly is not due to active-sterile neutrino oscillations, it is likely that it can be solved with a revaluation of the ${}^{235}\mathrm{U}$ reactor antineutrino flux. However, the ${}^{238}\mathrm{U}$, ${}^{239}\text{Pu}$, and ${}^{241}\mathrm{Pu}$ fluxes, which have larger uncertainties, could also be significantly different from the theoretical predictions.

We study the thermodynamic phase diagram of three-dimensional $sl(N;\mathbb{R})$ higher spin black holes. By analyzing the semiclassical partition function we uncover a rich structure that includes Hawking-Page transitions to the ${\mathrm{AdS}}_3$ vacuum, first order phase transitions among black hole states, and a second order critical point. Our analysis is explicit for $N=4$ but we extrapolate some of our conclusions to arbitrary $N$. In particular, we argue that even $N$ is stable in the ensemble under consideration but odd $N$ is not.

Statistical systems near a classical critical point have been intensively studied from both theoretical and experimental points of view. In particular, correlation functions are of relevance in comparing theoretical models with the experimental data of real systems. In order to compute physical quantities near a critical point, one needs to know the model at the critical (conformal) point. In this line, recent progress in the knowledge of conformal field theories, through the conformal bootstrap, gives the hope of getting some interesting results also outside of the critical point. In this paper, we will review and clarify how, starting from the knowledge of the critical correlators, one can calculate in a safe way their behavior outside the critical point. The approach illustrated requires the model to be just scale invariant at the critical point. We will clarify the method by applying it to different kind of perturbations of the 2D Ising model.

Einstein’s vierbein formulation of general relativity based on the notion of distant parallelism (teleparallelism) naturally introduces a covariant surface term in addition to the Einstein-Hilbert action. We investigate the action principle in teleparallelism with the existence of spacetime boundaries and find that the covariant surface term exactly eliminates all the unwanted surface terms that reside in the metric formulation of general relativity, in the role of a Gibbons-Hawking-York (GHY) term. The identity of such a covariant GHY term is further confirmed by the recovery of the correct black hole entropy from the free energy due to the spacetime boundary. These results indicate that the vierbein formulation of gravity generally exhibits a well-posed action principle and readily admits the path-integral approach to quantization.

We present a novel cosmological solution in the framework of extended quasidilaton theory which underwent scrutiny recently. We only consider terms that do not generate the Boulware-Deser degree of freedom, hence the ghost-free quasidilaton theory, and show three new branches of cosmological evolution therein. One of the solutions passes the perturbative stability tests. This new solution exhibits a late time self-acceleration and all graviton polarizations acquire masses that converge to a constant in the asymptotic future. Moreover, all modes propagate at the speed of light. We propose that this solution can be used as a benchmark model for future phenomenological studies.

A new family of spherically symmetric inhomogeneous solutions of Brans-Dicke gravity is generated using conformal transformation techniques and the Fonarev solution of general relativity as a seed. The latter is mapped from the Einstein to the Jordan conformal frame and this Jordan frame version constitutes a new solution of Brans-Dicke theory. The Brans-Dicke scalar field self-interacts with a power-law or inverse power-law potential in the Jordan frame. The new 4-parameter family of geometries thus generated, which is dynamical and asymptotically Friedmann-Lemaître-Robertson-Walker, contains as special cases two previously known classes of solutions and solves also the field equations of $f(\mathcal{R})={\mathcal{R}}^n$ gravity, which can also be seen as an $\omega =0$ Brans-Dicke theory with a potential.

We search for sterile neutrinos in the holographic dark energy cosmology by using the latest observational data. To perform the analysis, we employ the current cosmological observations, including the cosmic microwave background temperature power spectrum data from the Planck mission, the baryon acoustic oscillation measurements, the type Ia supernova data, the redshift space distortion measurements, the shear data of weak lensing observation, the Planck lensing measurement, and the latest direct measurement of $H_0$ as well. We show that, compared to the $\mathrm{\Lambda }\mathrm{CDM}$ cosmology, the holographic dark energy cosmology with sterile neutrinos can relieve the tension between the Planck observation and the direct measurement of $H_0$ much better. Once we include the $H_0$ measurement in the global fit, we find that the hint of the existence of sterile neutrinos in the holographic dark energy cosmology can be given. Under the constraint of the all-data combination, we obtain $N_{\mathrm{eff}}=3.76\pm 0.26$ and $m_{\nu ,\text{sterile}}^{\mathrm{eff}}<0.215\mathrm{eV}$, indicating that the detection of $\mathrm{\Delta }{N}_{\mathrm{eff}}>0$ in the holographic dark energy cosmology is at the $2.75\sigma$ level and the massless or very light sterile neutrino is favored by the current observations.

In this work, we calculate the $CP$-averaged branching ratios and direct $CP$-violating asymmetries of the quasi-two-body decays $B_{(s)}\to P{\rho }^{\prime }(1450),P{\rho }^{\prime \prime }(1700)\to P\pi \pi$ by employing the perturbative QCD (PQCD) factorization approach, where $P$ is a light pseudoscalar meson $K$, $\pi$, $\eta$, and ${\eta }^{\prime }$. The considered decay modes are studied in the quasi-two-body framework by parametrizing the two-pion distribution amplitude ${\mathrm{\Phi }}_{\pi \pi }^{\mathrm{P}}$. The $P$-wave timelike form factor $F_{\pi }$ in the resonant regions associated with the ${\rho }^{\prime }(1450)$ and ${\rho }^{\prime \prime }(1700)$ is estimated based on available experimental data. The PQCD predictions for the $CP$-averaged branching ratios of the decays $B_{(s)}\to P{\rho }^{\prime }(1450),P{\rho }^{\prime \prime }(1700)\to P\pi \pi$ are in the order of ${10}^{-7}-{10}^{-9}$. The branching ratios of the two-body decays $B_{(s)}\to P{\rho }^{\prime }(1450),P{\rho }^{\prime \prime }(1700)$ are extracted from the corresponding quasi-two-body decay modes. The whole pattern of the squared pion form factor $|F_{\pi }{|}^2$ measured by BABAR Collaboration could also be understood based on our studies. The PQCD predictions in this work will be tested by the precise data from the LHCb and the future Belle II experiments.

We calculate the single transverse spin asymmetries (SSA) for forward inclusive particle production in pp and pA collisions using a hybrid approach. It is shown that the Sivers type contribution to the SSA drops out due to the color entanglement effect, whereas the fragmentation contribution to the spin asymmetry is not affected by the color entanglement effect. This finding offers a natural solution for the sign mismatch problem.