We evaluate the $\pi NN$, $\pi \Sigma \Sigma$, $\pi \Lambda \Sigma$, $K\Lambda N$ and $K\Sigma N$ coupling constants and the corresponding monopole masses in lattice QCD with two flavors of dynamical quarks. The parameters representing the SU(3)-flavor symmetry are computed at the point where the three quark flavors are degenerate at the physical $s$-quark mass. In particular, we obtain $\alpha \equiv F/(F+D)=0.395(6)$. The quark-mass dependences of the coupling constants are obtained by changing the $u$- and the $d$-quark masses. We find that the SU(3)-flavor parameters have weak quark-mass dependence and thus the SU(3)-flavor symmetry is broken by only a few percent at each quark-mass point we consider.

It has been argued recently that parton showers based on color dipoles conflict with collinear factorization and do not lead to the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equation. We show that this conclusion is based on an inappropriate assumption, namely, the choice of the gluon energy as evolution variable. We further show numerically that Monte Carlo programs based on dipole showers with “infrared-sensible” evolution variables reproduce the DGLAP equation both in asymptotic form as well as in comparison to the leading behavior of second-order QCD matrix elements.

In this paper we investigate the strong decays of the two newly observed bottom-strange mesons $B_{s1}(5830)$ and $B_{s2}^{*}(5840)$ in the framework of the quark pair creation model. The two-body strong decay widths of $B_{s1}(5830{)}^0\to B^{*+}{K}^{-}$ and $B_{s2}^{*}(5840{)}^0\to B^{+}{K}^{-}$, $B^{*+}{K}^{-}$ are calculated by considering $B_{s1}(5830)$ to be a mixture between $|{}^{1}P_1⟩$ and $|{}^{3}P_1⟩$ states, and $B_{s2}^{*}(5840)$ to be a $|{}^{3}P_2⟩$ state. The double pion decay of $B_{s1}(5830)$ and $B_{s2}^{*}(5840)$ is supposed to occur via the intermediate state $\sigma$ and $f_0(980)$. Although the double pion decay widths of $B_{s1}(5830)$ and $B_{s2}^{*}(5840)$ are smaller than the two-body strong decay widths of $B_{s1}(5830)$ and $B_{s2}^{*}(5840)$, one suggests future experiments to search the double pion decays of $B_{s1}(5830)$ and $B_{s2}^{*}(5840)$ due to their sizable decay widths.

We perform a Dalitz plot analysis of the decay $D_s^{+}\to K^{+}{K}^{-}{\pi }^{+}$ with the CLEO-c data set of $586{\mathrm{pb}}^{-1}$ of $e^{+}{e}^{-}$ collisions accumulated at $\sqrt{s}=4.17\mathrm{GeV}$. This corresponds to about $0.57\times {10}^6$ $D_s^{\pm }{D}_s^{*\mp }$ pairs from which we select 14 400 candidates with a background of roughly 15%. In contrast to previous measurements we find good agreement with our data only by including an additional $f_0(1370){\pi }^{+}$ contribution. We measure the magnitude, phase, and fit fraction of $K^{*}(892{)}^0{K}^{+}$, $\varphi (1020){\pi }^{+}$, $K_0^{*}(1430)K^{+}$, $f_0(980){\pi }^{+}$, $f_0(1710){\pi }^{+}$, and $f_0(1370){\pi }^{+}$ contributions and limit the possible contributions of other $KK$ and $K\pi$ resonances that could appear in this decay.

We calculate the orbital angular momentum of the “quark” in the scalar diquark model as well as that of the electron in QED (to order $\alpha$). We compare the orbital angular momentum obtained from the Jaffe-Manohar decomposition to that obtained from the Ji relation and estimate the importance of the vector potential in the definition of orbital angular momentum.

Motivated by slow-roll inflationary cosmology we study a scalar unparticle weakly coupled to a Higgs field in the broken symmetry phase. The mixing between the unparticle and the Higgs field results in a seesaw type matrix and the mixing angles feature a Mikheyev-Smirnov-Wolfenstein (MSW) effect as a consequence of the unparticle field being noncanonical. We find two (MSW) resonances for small and large spacelike momenta. The unparticlelike mode features a nearly flat potential with spinodal instabilities and a large expectation value. An effective potential for the unparticlelike field is generated from the Higgs potential, but with couplings suppressed by a large power of the small seesaw ratio. The dispersion relation for the Higgs-like mode features an imaginary part even at “tree level” as a consequence of the fact that the unparticle field describes a multiparticle continuum. Mixed unparticle-Higgs propagators reveal the possibility of oscillations, albeit with short coherence lengths. The results are generalized to the case in which the unparticle features a mass gap, in which case a low energy MSW resonance may occur for lightlike momenta depending on the scales. Unparticle-Higgs mixing leads to an effective unparticle potential of the new-inflation form. Slow-roll variables are suppressed by seesaw ratios and the anomalous dimensions and favor a red spectrum of scalar perturbations consistent with cosmic microwave background data.

We give an explicit form for the Lorentzian vertices recently introduced for possibly defining the dynamics of loop quantum gravity. As a result of doing so, a natural regularization of the vertices is suggested. The regularized vertices are then proven to be finite. An interpretation of the regularization in terms of a gauge fixing is also given.

The detection of by-products from particle annihilations in galactic halos would provide important information about the nature of the dark matter. Observational evidence for a local excess of high-energy positrons has motivated recent models with an additional interaction between dark matter particles that can result in a Sommerfeld enhancement to the cross section. In such models, the cross section for annihilation becomes velocity-dependent and may enhance the dark matter annihilation rate in the solar neighborhood relative to the rate in the early Universe sufficiently to source observed fluxes of high-energy positrons. We demonstrate that, for particle interaction cross sections that increase with decreasing velocity, the kinematical structures of dark matter halos with interior density profiles shallower than isothermal, such as Navarro-Frenk-White or Einasto halos, may induce a further enhancement owing to the position-dependent velocity distribution. We provide specific examples for the increase in the annihilation rate with a cross section enhanced by the Sommerfeld effect. In dark matter halos like that of the Milky Way and Local Group dwarf galaxies, the effective cross section at the halo center can be significantly larger than its local value. The additional enhancement owing to halo kinematics depends upon the parameters of any model, but is a prediction of certain models aimed at explaining measured positron fluxes and can exceed an order of magnitude.

We study diffractive vector-meson photoproduction using string theory via AdS/CFT. The large $s$ behavior of the cross sections for the scattering of the vector meson $V$ on a proton is dominated by the soft Pomeron, ${\sigma }_V\sim s^{2ϵ-2{\alpha }_P^{\prime }/B}$, where from the string theory model of [arXiv:hep-th/0501039], $ϵ$ is approximately $1/7$ below 10 GeV, and $1/11$ for higher, but still sub-Froissart, energies. This is due to the production of black holes in the dual gravity. In $\varphi$ photoproduction the mesonic Regge poles do not contribute, so that we deal with a pure Pomeron contribution. This allows for an experimental test. At the gauge theory “Planck scale” of about 1–2 GeV, the ratios of the soft Pomeron contributions to the photoproduction cross sections of different vector mesons involve not only the obvious quark model factors, but also the Boltzmann factors $e^{-4M_V/T_0}$, with $T_0$ the temperature of the dual black hole. The presence of these factors is confirmed in the experimental data for $\rho$, $\omega$, $\varphi$, $J/\psi$, and $\psi (2S)$ photoproduction and is compatible with the meager ${\rm Y}$ photoproduction data. Throughout, we use vector-meson dominance, and from the data we obtain $T_0$ of about 1.3 GeV, i.e. the gauge theory “Planck scale,” as expected. The ratio of the experimental soft Pomeron onset scale ${\widehat{E}}_R\sim 9\mathrm{GeV}$ and of the gauge theory Planck scale, $T_0\sim 1.3\mathrm{GeV}$, conforms to the theoretical prediction of $N_c^2/N_c^{1/4}$.

The properties of compact stars made of massive bosons with a repulsive self-interaction mediated by vector mesons are studied within the mean-field approximation and general relativity. We demonstrate that there exists a scaling property for the mass-radius curve for arbitrary boson masses and interaction strengths which results in a universal mass-radius relation. The radius remains nearly constant for a wide range of compact star masses. The maximum stable mass and radius of boson stars are determined by the interaction strength and scale with the Landau mass and radius. Both the maximum mass and the corresponding radius increase linearly with the interaction strength so that they can be radically different compared to the other families of boson stars where interactions are ignored.

We briefly review existing proposals for the renormalization of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and study the numerical effects of several of them on the $W$-boson hadronic partial decay widths. We then use these results to evaluate the relative shifts on the CKM parameters $|V_{ij}{|}^2$ induced by the quark-mixing renormalization effects, as well as their scheme dependence. We also discuss the implications of this analysis for the most precise unitarity test of the CKM matrix.

We construct a new solution of five-dimensional gravity coupled to a dilaton which encodes essential features of holographic QCD backgrounds dynamically. In particular, it implements linear confinement, i.e., the area-law behavior of the Wilson loop, by means of a dynamically deformed anti-de Sitter metric. The predicted square masses of the light-flavored natural-parity mesons and their excitations lie on linear trajectories of an approximately universal slope with respect to both radial and spin quantum numbers and are in satisfactory agreement with experimental data.

We discuss the anomalous magnetic moment of fermion in a realistic $SU(3)$ model of gauge-Higgs unification compactified on an orbifold $S^1/Z_2$ including $Z_2$-odd bulk mass for fermions. An operator analysis implies that the anomalous magnetic moment should be finite and predictable, even though higher dimensional gauge theories are nonrenormalizable. Our main purpose is to clarify the cancellation mechanism of the UV divergences appearing in various types of Feynman diagrams. The cancellation of divergence turns out to take place between the contributions of the partners in the Higgs-like mechanism present in the nonzero Kaluza-Klein modes to form massive gauge bosons. It is also argued that the cancellation may be attributed to the quantum mechanical supersymmetry hidden in the scenario of gauge-Higgs unification.

Currently, a number of experiments are searching for vacuum magnetic birefringence and dichroism, i.e. for dispersive and absorptive features in the propagation of polarized light along a transverse magnetic field in vacuum. In this paper we calculate the standard model contributions to these signatures, thereby illuminating the discovery potential of such experiments in the search for new physics. We discuss the three main sources for a standard model contribution to a dichroism signal: photon splitting, neutrino pair production and production of gravitons.

Using a sample of $2.59\times {10}^7$ $\psi (2S)$ decays collected by the CLEO-c detector, we present results of a study of ${\chi }_{c0}$ and ${\chi }_{c2}$ decays into two-meson final states. We present the world’s most precise measurements of the ${\chi }_{cJ,(J=0,2)}\to {\pi }^{+}{\pi }^{-}$, ${\pi }^0{\pi }^0$, $K^{+}{K}^{-}$, $K_S^0{K}_S^0$, $\eta \eta$, and ${\eta }^{\prime }{\eta }^{\prime }$ branching fractions, and a search for ${\chi }_c$ decays into $\eta {\eta }^{\prime }$. These results shed light on the mechanism of charmonium decays into pseudoscalar mesons.

We present a Dalitz plot analysis of charmless $B^{\pm }$ decays to the final state ${\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp }$ using a sample of $(465\pm 5)\times {10}^6$ $B\overline{B}$ pairs collected by the BABAR experiment at $\sqrt{s}=10.58\mathrm{GeV}$. We measure the branching fractions $\mathcal{B}(B^{\pm }\to {\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp })=(15.2\pm 0.6\pm 1.2\pm 0.4)\times {10}^{-6}$, $\mathcal{B}(B^{\pm }\to {\rho }^0(770){\pi }^{\pm })=(8.1\pm 0.7\pm {1.2}_{-1.1}^{+0.4})\times {10}^{-6}$, $\mathcal{B}(B^{\pm }\to f_2(1270){\pi }^{\pm })=(1.57\pm 0.42\pm {0.16}_{-0.19}^{+0.53})\times {10}^{-6}$, and $\mathcal{B}(B^{\pm }\to {\pi }^{\pm }{\pi }^{\pm }{\pi }^{\mp }\mathrm{\text{nonresonant}})=(5.3\pm 0.7\pm {0.6}_{-0.5}^{+1.1})\times {10}^{-6}$, where the uncertainties are statistical, systematic, and model-dependent, respectively. Measurements of branching fractions for the modes $B^{\pm }\to {\rho }^0(1450){\pi }^{\pm }$ and $B^{\pm }\to f_0(1370){\pi }^{\pm }$ are also presented. We observe no significant direct $CP$ asymmetries for the above modes, and there is no evidence for the decays $B^{\pm }\to f_0(980){\pi }^{\pm }$, $B^{\pm }\to {\chi }_{c0}{\pi }^{\pm }$, or $B^{\pm }\to {\chi }_{c2}{\pi }^{\pm }$.

We discuss the problem of an electron in the presence of a magnetic field in Podolsky’s generalized electrodynamics. The problem of the energy levels is then formulated using noncommutative coordinates, and its physical consequences are analyzed.

In a recent paper a systematic study on shearing expansion-free spherically symmetric distributions was presented. As a particular case of such systems, the Skripkin model was mentioned, which corresponds to a nondissipative perfect fluid with a constant energy density. Here we show that such a model is inconsistent with junction conditions. It is shown that in general for any nondissipative fluid distribution, the expansion-free condition requires the energy density to be inhomogeneous. As an example we consider the case of dust, which allows for a complete integration.

We derive several no-go theorems in the context of massive type IIA string theory compactified to four dimensions in a way that, in the absence of fluxes, preserves $\mathcal{N}=1$ supersymmetry. Our derivation is based on the dilaton, Kähler and complex structure moduli dependence of the potential of the four-dimensional effective field theory, that is generated by the presence of $D6$-branes, $O6$-planes, RR fluxes, NSNS 3-form flux, and geometric fluxes. To demonstrate the usefulness of our theorems, we apply them to the most commonly studied class of toroidal orientifolds. We show that for all but two of the models in this class the slow-roll parameter $ϵ$ is bounded from below by numbers of order unity as long as the fluxes satisfy the Bianchi identities, ruling out slow-roll inflation and even the existence of de Sitter extrema in these models. For the two cases that avoid the no-go theorems, we provide some details of our numerical studies, demonstrating that small $ϵ$ can indeed be achieved. We stress that there seems to be an $\eta$-problem, suggesting that none of the models in this class are viable from a cosmological point of view at least at large volume, small string coupling, and leading order in the ${\alpha }^{\prime }$-expansion.

The main objective of this article is to recast the hypermultiplets sector of five-dimensional ungauged $\mathcal{N}=2$ supergravity into a manifestly symplectic-covariant form. We propose that this facilitates the construction and analysis of hypermultiplet fields coupled to $p$-brane sources and discuss examples.