Assuming the dominance of the spin-spin interaction in a diquark, we point out that the mass difference in the beauty sector $M(Z_b^{\prime }{)}^{\pm }-M(Z_b{)}^{\pm }$ scales with quark masses as expected in QCD, with respect to the corresponding mass difference $M(Z_c^{\prime }{)}^{\pm }-M(Z_c{)}^{\pm }$. Notably, we show that the decays $\mathrm{\Upsilon }(10890)\to \mathrm{\Upsilon }(nS){\pi }^{+}{\pi }^{-}$ and $\mathrm{\Upsilon }(10890)\to (h_b(1P),h_b(2P)){\pi }^{+}{\pi }^{-}$ are compatible with heavy quark spin conservation if the contributions of $Z_b,Z_b^{\prime }$ intermediate states are taken into account, $\mathrm{\Upsilon }(10890)$ being either a $\mathrm{\Upsilon }(5S)$ or the beauty analog of $Y_c(4260)$. Belle results on these decays support the quark spin wave function of the $Z$ states as tetraquarks. We also consider the role of light quark spin nonconservaton in $Z_b,Z_b^{\prime }$ decays into $B{B}^{*}$ and $B^{*}{B}^{*}$. Indications of possible signatures of the still missing $X_b$ resonance are proposed.

We investigate the angular momentum decomposition with a quantum electrodynamics example to clarify the proton spin decomposition debates. We adopt the light-front formalism where the parton model is well defined. We prove that the sum of fermion and boson angular momenta is equal to half the sum of the two gravitational form factors $A(0)$ and $B(0)$, as is well known. However, the suggestion to make a separation of the above relation into the fermion and boson pieces, as a way to measure the orbital angular momentum of fermions or bosons, respectively, is not justified from our explicit calculation.

We examine matter-induced $CPT$ violation effects in long-baseline electron neutrino appearance experiments in a low energy neutrino factory setup. Assuming $CPT$ invariance in vacuum, the magnitude of $CPT$ violating asymmetry in matter has been estimated using the exact expressions for the transition probabilities. The dependence of the asymmetry on the oscillation parameters like mixing angles, mass squared differences, as well as on the Dirac $CP$ violating phase has been investigated.

Second-order Newton equations of motion for a radiating particle are presented. It is argued that the trajectories obeying them also satisfy the Abraham-Lorentz-Dirac (ALD) equations for general 3D motions in the nonrelativistic and relativistic limits. The case of forces depending on only the proper time is here considered. For these properties to hold, it is sufficient that the external force be infinitely smooth and that a Landau-Lifshitz series formed with its time derivatives converges. This series defines in a special local way the effective forces entering the Newton equations. When the external force vanishes in an open vicinity of a given time, the effective one also becomes null. Thus, the proper solutions of the effective equations cannot show runaway or preacceleration effects. The Newton equations are numerically solved for a pulsed force given by an analytic function along the proper time axis. The simultaneous satisfaction of the ALD equations is numerically checked. Furthermore, a set of modified ALD equations for almost everywhere infinitely smooth forces, but including steplike discontinuities in some points, is also presented. The form of the equations supports the statement argued in a previous work, that the causal Lienard-Wiechert field solution surrounding a radiating particle implies that the effective force on the particle should instantaneously vanish when the external force is retired. The modified ALD equations proposed in the previous work are here derived in a generalized way including the same effect also when the force is instantly connected. The possibility of deriving a pointlike model showing a finite mass and an infinite electromagnetic energy from a reasonable Lagrangian theory is also started to be investigated here.

While LHC8 Higgs mass and sparticle search constraints favor a multi-TeV value of soft SUSY breaking terms, electroweak naturalness favors a superpotential Higgsino mass $\mu \sim 100–200\mathrm{GeV}$: the mismatch results in an apparent little hierarchy characterized by $\mu \ll m_{\text{soft}}$ (with $m_{\text{soft}}\sim m_{3/2}$ in gravity mediation). It has been suggested that the little hierarchy arises from a mismatch between Peccei-Quinn (PQ) and hidden sector intermediate scales $v_{\mathrm{PQ}}\ll m_{\text{hidden}}$. We examine the Murayama-Suzuki-Yanagida model of radiatively driven PQ symmetry breaking which not only generates a weak scale value of $\mu$ but also produces intermediate scale Majorana masses for right-hand neutrinos. For this model, we show ranges of parameter choices with multi-TeV values of $m_{3/2}$ which can easily generate values of $\mu \sim 100–200\mathrm{GeV}$ so that the apparent little hierarchy suggested from data emerges quite naturally. In such a scenario, dark matter would be comprised of an axion plus a Higgsino-like weakly-interacting massive particle admixture where the axion mass and Higgsino masses are linked by the value of the PQ scale. The required light Higgsinos should ultimately be detected at a linear $e^{+}{e}^{-}$ collider with $\sqrt{s}>2m(\text{Higgsino})$.

We consider theories where lepton flavor is violated, in particular concentrating on the four fermion operator consisting of three electrons and a tau. Strong constraints are available from existing searches for $\tau \to eee$, requiring the scale of the contact interaction to be $\lesssim 1/(9\mathrm{TeV}{)}^2$. We reexamine this type of physics, assuming that the particles responsible are heavy (with masses $\gtrsim \mathrm{TeV}$) such that a contact interaction description continues to be applicable at the energies for a future $e^{+}{e}^{-}$ collider. We find that the process $e^{+}{e}^{-}\to e\tau$ can be a very sensitive probe of this kind of physics (even for very conservative assumptions about the detector performance), already improving upon the tau decay bounds to $\lesssim 1/(11\mathrm{TeV}{)}^2$ at collider energy $\sqrt{s}=500\mathrm{GeV}$, or reaching $\lesssim 1/(35\mathrm{TeV}{)}^2$ for $\sqrt{s}=3\mathrm{TeV}$. Even stronger bounds are possible at $e^{-}{e}^{-}$ colliders in the same energy range.

In this paper we consider a Higgs boson with mass and other properties compatible with those of the recently discovered Higgs particle at the LHC, and explore the possibility of new Higgs leptonic decays, beyond the standard model, with the singular feature of being lepton flavor violating (LFV). We study these LFV Higgs decays, $H\to l_k{\overline{l}}_m$, within the context of the inverse seesaw model (ISS) and consider the most generic case where three additional pairs of massive right-handed singlet neutrinos are added to the standard model particle content. We require in addition that the input parameters of this ISS model are compatible with the present neutrino data and other constraints, like perturbativity of the neutrino Yukawa couplings. We present a full one-loop computation of the $\mathrm{BR}(H\to l_k{\overline{l}}_m)$ rates for the three possible channels, $l_k{\overline{l}}_m=\mu \overline{\tau }$, $e\overline{\tau }$, $e\overline{\mu }$, and analyze in full detail the predictions as functions of the various relevant ISS parameters. We study in parallel the correlated one-loop predictions for the radiative decays, $l_m\to l_k\gamma$, within this same ISS context, and require full compatibility of our predictions with the present experimental bounds for the three radiative decays, $\mu \to e\gamma$, $\tau \to \mu \gamma$, and $\tau \to e\gamma$. After exploring the ISS parameter space we conclude on the maximum allowed LFV Higgs decay rates within the ISS.

We study 20 charmless hadronic $B\to f_{1}P$ decays in the perturbative QCD (pQCD) formalism with $B$ denoting $B_u$, $B_d$, and $B_s$ mesons; $P$ standing for the light pseudoscalar mesons; and $f_1$ representing axial-vector mesons $f_1(1285)$ and $f_1(1420)$ that result from a mixing of quark-flavor $f_{1q}[\frac{u\overline{u}+d\overline{d}}{\sqrt{2}}]$ and $f_{1s}[s\overline{s}]$ states with the angle ${\varphi }_{f_1}$. The estimations of $CP$-averaged branching ratios and $CP$ asymmetries of the considered $B\to f_{1}P$ decays, in which the $B_s\to f_{1}P$ modes are investigated for the first time, are presented in the pQCD approach with ${\varphi }_{f_1}\sim 24°$ from recently measured $B_{d/s}\to J/\psi f_1(1285)$ decays. It is found that (a) the tree (penguin) dominant $B^{+}\to f_1{\pi }^{+}(K^{+})$ decays with large branching ratios [$\mathcal{O}({10}^{-6})$] and large direct $CP$ violations (around 14%–28% in magnitude) simultaneously are believed to be clearly measurable at the LHCb and Belle II experiments; (b) the $B_d\to f_1{K}_S^0$ and $B_s\to f_1(\eta ,{\eta }^{\prime })$ decays with nearly pure penguin contributions and safely negligible tree pollution also have large decay rates in the order of ${10}^{-6}–{10}^{-5}$, which can be confronted with the experimental measurements in the near future; (c) as the alternative channels, the $B^{+}\to f_1({\pi }^{+},K^{+})$ and $B_d\to f_1{K}_S^0$ decays have the supplementary power in providing more effective constraints on the Cabibbo-Kobayashi-Maskawa weak phases $\alpha$, $\gamma$, and $\beta$, correspondingly, which are explicitly analyzed through the large decay rates and the direct and mixing-induced $CP$ asymmetries in the pQCD approach and are expected to be stringently examined by the measurements with high precision; (d) the weak annihilation amplitudes play important roles in the $B^{+}\to f_1(1420)K^{+}$, $B_d\to f_1(1420)K_S^0$, $B_s\to f_1(1420){\eta }^{\prime }$ decays, and so on, which would offer more evidence, once they are confirmed by the experiments, to identify the soft-collinear effective theory and the pQCD approach on the evaluations of annihilation diagrams and to help further understand the annihilation mechanism in the heavy $B$ meson decays; (e) combined with the future precise tests, the considered decays can provide more information to further understand the mixing angle ${\varphi }_{f_1}$ and the nature of the $f_1$ mesons in depth after the confirmations on the reliability of the pQCD calculations in the present work.

We discuss generalizations of the Brodsky–Lepage–Mackenzie optimization procedure for renormalization group invariant quantities. In this respect, we discuss in detail the features and construction of the $\{\beta \}$-expansion presentation instead of the standard perturbative series with regard to the Adler $D$ function and Bjorken polarized sum rules obtained in the order of $\mathcal{O}({\alpha }_s^4)$. Based on the $\{\beta \}$ expansion, we analyze different schemes of optimization, including the corrected principle of maximal conformality, numerically illustrating their results. We suggest our scheme for the series optimization and apply it to both the above quantities.

We develop a Monte Carlo event generator based on the combination of a parton production formula including the effects of parton saturation (called the DHJ formula) and a hadronization process due to the Lund string fragmentation model. This event generator is designed for the description of hadron productions at forward rapidities and in a wide transverse momentum range in high-energy proton-proton collisions. We analyze transverse momentum spectra of charged hadrons as well as identified particles, including pion, kaon, and (anti)proton at RHIC energy and ultraforward neutral pion spectra from the LHCf experiment. We compare our results to those obtained in other models based on parton-hadron duality and fragmentation functions.

A large cross section for $e^{+}{e}^{-}\to {\mathrm{\Lambda }}_c^{+}{\overline{\mathrm{\Lambda }}}_c^{-}$ pair production near its threshold provides an opportunity to study the charm baryon ${\mathrm{\Lambda }}_c^{+}/{\overline{\mathrm{\Lambda }}}_c^{-}$ at a $\tau$-charm factory with $e^{+}{e}^{-}$ collisions. We call for the determination of the ${\mathrm{\Lambda }}_c^{+}/{\overline{\mathrm{\Lambda }}}_c^{-}$ spin using the process $e^{+}{e}^{-}\to {\mathrm{\Lambda }}_c^{+}{\overline{\mathrm{\Lambda }}}_c^{-},{\mathrm{\Lambda }}_c^{+}\to p{K}_S^0$, and we present a formula and a method to estimate the statistical significance for spin assignment $J=\frac{1}{2}$ and $J=\frac{3}{2}$. A Monte Carlo study shows that the significance is sensitive to the number of observed events. A few hundred observed signal events will yield the statistical significance larger than five standard deviations.

We study the anomalously large rates of some hadronic transitions observed in heavy quarkonia using a constituent quark model that has been successful in describing meson and baryon phenomenology. QCD multipole expansion (QCDME) is used to describe the hadronic transitions. The hybrid intermediate states needed in the QCDME method are calculated in a natural, parameter-free extension of our constituent quark model based on the quark confining string scheme. Some of the anomalies are explained due to the presence of a hybrid state with a mass near the one of the decaying resonance, whereas others are justified by the presence of molecular components in the wave function. Certain unexpected results are pointed out.

Motivated by a $\sim 3\sigma$ excess recorded by the CMS experiment at the LHC around a mass of order $\sim 137\mathrm{GeV}$ in $ZZ\to 4l$ and $\gamma \gamma$ samples, we analyze the discovery potential of a second neutral Higgs boson in the Supersymmetric $B-L$ extension of the Standard Model at the CERN machine. We confirm that a double Higgs peak structure can be generated in this framework, with $CP$-even Higgs boson masses at $\sim 125\mathrm{GeV}$ and $\sim 137\mathrm{GeV}$, unlike the case of the Minimal Supersymmetric Standard Model.

In this paper we examine the sensitivity of the Long Baseline Neutrino Oscillation Experiment to the inclusion of two new sterile neutrino flavors with masses in the eV range. We implement a model with a modified Casas-Ibarra parametrization which can accommodate medium scale mass eigenstates and introduce a new complex mixing angle. We explore the new mixing angle parameter space and demonstrate how LBNE can be used to either provide evidence for or rule out a particular model of sterile neutrinos. Certain three-flavor $CP$-violation scenarios cannot be distinguished from the sterile neutrinos. Constraints from the Daya Bay reactor experiment and T2K are used to help lift this degeneracy.

Differential cross sections for the production of $Z$ bosons or off-shell photons ${\gamma }^{*}$ in association with jets are measured in proton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96\mathrm{TeV}$ using the full data set collected with the Collider Detector at Fermilab in Tevatron run II and corresponding to $9.6{\mathrm{fb}}^{-1}$ of integrated luminosity. Results include first measurements at CDF of differential cross sections in events with a $Z/{\gamma }^{*}$ boson and three or more jets, the inclusive cross section for production of $Z/{\gamma }^{*}$ and four or more jets, and cross sections as functions of various angular observables in lower jet-multiplicity final states. Measured cross sections are compared to several theoretical predictions.

We discuss the construction of gaugings in recent models of $E_7$ extended geometries, focusing on the two inequivalent $SL(8)$ truncations of the theory. In these sectors the conditions for the generation of gaugings in the $\mathbf{36}$, ${\mathbf{36}}^{\prime }$, $\mathbf{420}$ and ${\mathbf{420}}^{\prime }$ representations of $E_{7(7)}$ can be compactly expressed in terms of objects which are in the fundamental representation of $SL(8)$, making the search of solutions simpler. We present a no-go theorem showing that neither of these truncations lead to the new $SO(8)$ dyonic gaugings, at least if the so-called section conditions are implemented. We also show that these truncations can be used to obtain the generalized twist of the seven-sphere, leading to the electric $SO(8)$ gaugings.

The objective of the present paper is to analyze the phase transition of asymptotically anti–de Sitter (AdS) black-hole solutions in Lovelock gravity in the presence of nonlinear electrodynamics. First, we present the asymptotically AdS black-hole solutions for two classes of the Born-Infeld type of nonlinear electrodynamics coupled (separately) with Einstein, Gauss-Bonnet, and third-order Lovelock gravity. Then, in order to discuss the phase transition, we calculate both the heat capacity and the Ricci scalar of the thermodynamical line element. We present a comparison between the singular points of the Ricci scalar using the geometrothermodynamics method and the corresponding vanishing points of the heat capacity in the canonical ensemble. In addition, we discuss the effects of both Lovelock and nonlinear electrodynamics on the phase transition points.

The frequencies of $r$-mode oscillations of rotating neutron stars can be useful for guiding and interpreting gravitational-wave and electromagnetic observations. The frequencies of slowly rotating, barotropic, and nonmagnetic Newtonian stars are well known but subject to various corrections. After making simple estimates of the relative strengths of these corrections, we conclude that relativistic corrections are likely to be the most important. For this reason we extend the formalism of Lockitch et al. [Phys. Rev. D 68, 124010 (2003)], who consider relativistic polytropes, to the case of realistic equations of state. This formulation results in perturbation equations which are solved using a spectral method. We find that for realistic equations of state, the $r$-mode frequency ranges from 1.39–1.57 times the spin frequency of the star when the relativistic compactness parameter ($M/R$) is varied over the astrophysically motivated interval 0.11–0.31. The results presented here are relevant to the design of gravitational wave and electromagnetic $r$-mode searches, and following a successful $r$-mode detection could help constrain the high-density equation of state.

The relic abundance of particle and antiparticle dark matter (DM) need not be vastly different in thermal asymmetric dark matter (ADM) models. By considering the effect of a primordial asymmetry on the thermal Boltzmann evolution of coupled DM and anti-DM, we derive the requisite annihilation cross section. This is used in conjunction with cosmic microwave background and Fermi-LAT gamma-ray data to impose a limit on the number density of anti-DM particles surviving thermal freeze-out. When the extended gamma-ray emission from the Galactic Center is reanalyzed in a thermal ADM framework, we find that annihilation into $\tau$ leptons prefer anti-DM number densities 1%–4% that of DM while the $b$-quark channel prefers 50%–100%.

The Weyl-Wigner-Groenewold-Moyal formalism of deformation quantization is applied to the closed Friedmann-Lemaître-Robertson-Walker cosmological model. We show that the phase space average for the surface of the apparent horizon is quantized in units of the Planck’s surface, and that the total entropy of the Universe is also quantized. Taking into account these two concepts, it is shown that ’t Hooft conjecture on the cosmological holographic principle in radiation and dust dominated quantum universes is satisfied as a manifestation of quantization. This suggests that the entire Universe (not only inside the apparent horizon) can be seen as a two-dimensional information structure encoded on the apparent horizon.