We provide new values for the model parameters of the covariant constituent quark model (with built-in infrared confinement) in the meson sector by a fit to the leptonic decay constants and a number of electromagnetic decays. We then evaluate, in a parameter-free way, the form factors of the $B(B_s)\to P(V)$ transitions in the full kinematical region of momentum transfer. As an application of our results, we calculate the widths of the nonleptonic $B_s$ decays into $D_s^{-}{D}_s^{+}$, $D_s^{*-}{D}_s^{+}+D_s^{-}{D}_s^{*+}$, and $D_s^{*-}{D}_s^{*+}$. These modes give the largest contribution to $\Delta \Gamma$ for the $B_s-{\overline{B}}_s$ system. We also treat the nonleptonic decay $B_s\to J/\psi \varphi$. Although this mode is color-suppressed, this decay has important implications for the search of possible $CP$-violating new-physics effects in $B_s-{\overline{B}}_s$ mixing.

Finite energy QCD sum rules involving both inverse- and positive-moment integration kernels are employed to determine the bottom-quark mass. The result obtained in the $\overline{\mathrm{MS}}$ scheme at a reference scale of 10 GeV is ${\overline{m}}_b(10\mathrm{GeV})=3623(9)\mathrm{MeV}$. This value translates into a scale-invariant mass ${\overline{m}}_b({\overline{m}}_b)=4171(9)\mathrm{MeV}$. This result has the lowest total uncertainty of any method, and is less sensitive to a number of systematic uncertainties that affect other QCD sum rule determinations.

The $T$-odd correlation coefficient $D$ in nuclear $\beta$ decay probes $CP$ violation in many theories beyond the standard model. We provide an analysis for how large $D$ can be in light of constraints from electric dipole moment (EDM) searches. We argue that the neutron EDM $d_n$ currently provides the strongest constraint on $D$, which is $10–{10}^3$ times stronger than current direct limits on $D$ (depending on the model). In particular, contributions to $D$ in leptoquark models (previously regarded as “EDM safe”) are more constrained than previously thought. Bounds on $D$ can be weakened only by fine-tuned cancellations or if theoretical uncertainties are larger than estimated in $d_n$. We also study implications for $D$ from mercury and deuteron EDMs.

In M. Sato, J. High Energy Phys. 07 (2010) 026, we proposed two models of M theory, the Hermitian 3-algebra model and Lie 3-algebra model. In this paper, we study the Lie 3-algebra model with a Lorentzian Lie 3-algebra. This model is ghost-free despite the Lorentzian 3-algebra. We show that our model satisfies two criteria as a model of M theory. First, we show that the model possesses $\mathcal{N}=1$ supersymmetry in 11 dimensions. Second, we show the model reduces to Banks-Fischler-Shenker-Susskind matrix theory with finite size matrices in a discrete light-cone quantization limit.

We present new models of nonlinear electromagnetism which satisfy the Noether-Gaillard-Zumino current conservation and are, therefore, self-dual. The new models differ from the Born-Infeld–type models in that they deform the Maxwell theory starting with terms like $\lambda (\partial F{)}^4$. We provide a recursive algorithm to find all higher-order terms in the action of the form ${\lambda }^n{\partial }^{4n}{F}^{2n+2}$, which are necessary for the $U(1)$ duality current conservation. We use one of these models to find a self-dual completion of the $\lambda (\partial F{)}^4$ correction to the open string action. We discuss the implication of these findings for the issue of UV finiteness of $\mathcal{N}=8$ supergravity.

We examine the static potential in the presence of flavors in the perturbative backreacted D4/D8 system from localized D8 branes, focusing, in particular, on the Sakai- Sugimoto model. For the case of long strings we find the flavor corrections to the static potential which are of exponential form. We then investigate shorter Wilson loops and express their energy analytically in terms of the lengths of two neighboring Wilson loops. Moreover, we find that beyond a certain scale the static force in the backreacted background is reduced compared to one in the probe limit, as expected due to screening effects. We also compare the string world sheets in the two backgrounds and find how they get modified by the backreaction. Our results are supported by numerical computations as well. Finally, we discuss our results in comparison with the lattice data.

A nonlocal gravity model, which does not assume the existence of a new dimensional parameter in the action and includes a function $f({\square }^{-1}R)$, with $\square$ the d’Alembertian operator, is considered. The model is proven to have de Sitter solutions only if the function $f$ satisfies a certain second-order linear differential equation. The de Sitter solutions corresponding to the simplest case, an exponential function $f$, are explored, without any restrictions on the parameters. If the value of the Hubble parameter is positive, the de Sitter solution is stable at late times, both for negative and for positive values of the cosmological constant. Also, the stability of the solutions with zero cosmological constant is discussed and sufficient conditions for it are established in this case. New de Sitter solutions are obtained, which correspond to the model with dark matter, and stability is proven in this situation for nonzero values of the cosmological constant.

Motion of test particles in the gravitational field associated with an electromagnetic plane wave is investigated. The interaction with the radiation field is modeled by a force term à la Poynting-Robertson entering the equations of motion given by the 4-momentum density of radiation observed in the particle’s rest frame with a multiplicative constant factor expressing the strength of the interaction itself. Explicit analytical solutions are obtained. Scattering of fields by the electromagnetic wave, i.e., scalar (spin 0), massless spin $\frac{1}{2}$ and electromagnetic (spin 1) fields, is studied too.

In the framework of Newtonian cosmology or general relativity it is simple to derive a mass scale below which collapsed structures are relatively devoid of baryons. We examine how the inclusion of a chameleon scalar field affects this baryonic Jeans mass, bearing in mind both the canonical case of a gravitational-strength coupling between the scalar field and matter, as well as the strong coupling regime wherein the coupling is very large. We find that baryon effects persist down to smaller scales in a chameleon theory than they do in ordinary general relativity, especially in the case of strong coupling. Several potentially observable consequences of this are identified.

We study quantum corrections to Friedmann-Robertson-Walker cosmology with a scalar field under the assumption that the dynamics are subject to renormalization group improvement. We use the Bianchi identity to relate the renormalization group scale to the scale factor and obtain the improved cosmological evolution equations. We study the solutions of these equations in the renormalization group fixed point regime, obtaining the time dependence of the scalar field strength and the Hubble parameter in specific models with monomial and trinomial quartic scalar field potentials. We find that power-law inflation can be achieved in the renormalization group fixed point regime with the trinomial potential, but not with the monomial one. We study the transition to the quasiclassical regime, where the quantum corrections to the couplings become small, and find classical dynamics as an attractor solution for late times. We show that the solution found in the renormalization group fixed point regime is also a cosmological fixed point in the autonomous phase space. We derive the power spectrum of cosmological perturbations and find that the scalar power spectrum is exactly scale invariant and bounded up to arbitrarily small times, while the tensor perturbations are tilted as appropriate for the background power-law inflation. We specify conditions for the renormalization group fixed point values of the couplings under which the amplitudes of the cosmological perturbations remain small.

The supermassive objects in galactic nuclei are thought to be the Kerr black holes predicted by general relativity, although a definite proof of their actual nature is still lacking. The most massive objects in AGN ($M\sim {10}^9$ $M_{\odot }$) seem to have a high radiative efficiency ($\eta \sim 0.4$) and a moderate mass accretion rate ($L_{\mathrm{bol}}/L_{\mathrm{Edd}}\sim 0.3$). The high radiative efficiency could suggest they are very rapidly rotating black holes. The moderate luminosity could indicate that their accretion disk is geometrically thin. If so, these objects could be excellent candidates to test the Kerr black hole hypothesis. An accurate measurement of the radiative efficiency of an individual AGN may probe the geometry of the space-time around the black hole candidate with a precision comparable to the one achievable with future space-based gravitational-wave detectors like LISA. A robust evidence of the existence of a black hole candidate with $\eta >0.32$ and accreting from a thin disk may be interpreted as an indication of new physics. For the time being, there are several issues to address before using AGN to test the Kerr paradigm, but the approach seems to be promising and capable of providing interesting results before the advent of gravitational wave astronomy.

We consider a two-flavor Polyakov–Nambu–Jona-Lasinio model where the Lagrangian includes an interaction term that explicitly breaks the ${\mathrm{U}}_A(1)$ anomaly. At finite temperature, the restoration of chiral and axial symmetries, signaled by the behavior of several observables, is investigated. We compare the effects of two regularizations at finite temperature, one of them, that allows high momentum quarks states, leading to the full recovery of chiral symmetry. From the analysis of the behavior of the topological susceptibility and of the mesonic masses of the axial partners, it is found in the SU(2) model that, unlike the SU(3) results, the recovery of the axial symmetry is not a consequence of the full recovery of the chiral symmetry. Thus, one needs to use an additional idea, by means of a temperature dependence of the anomaly coefficient, that simulates instanton suppression effects.

Weak vector-boson fusion provides a unique channel to directly probe the mechanism of electroweak symmetry breaking at hadron colliders. We present a method that allows to calculate total cross sections to next-to-next-to-leading order (NNLO) in QCD for an arbitrary $V^{*}{V}^{*}\to X$ process, the so-called structure function approach. By discussing the case of Higgs production in detail, we estimate several classes of previously neglected contributions and we argue that such method is accurate at a precision level well above the typical residual scale and PDF uncertainties at NNLO. Predictions for cross sections at the Tevatron and the LHC are presented for a variety of cases: the standard model Higgs (including anomalous couplings), neutral and charged scalars in extended Higgs sectors and (fermiophobic) vector resonance production. Further results can be easily obtained through the public use of the VBF@NNLO code.

The recently measured charge asymmetry of like-sign dimuon events by the D0 collaboration at Tevatron shows the $3.9\sigma$ deviation from the standard model prediction. In order to solve this mismatch, we investigate the right-handed current contributions to $B_s-{\overline{B}}_s$ and $B_d-{\overline{B}}_d$ mixings that are the major source of the like-sign dimuon events in $b\overline{b}$ production in general left-right models without imposing manifest or pseudomanifest left-right symmetry. We find the allowed region of new physics parameters satisfying the current experimental data.

We include the ${\eta }_c$ meson into the $\eta \mathrm{\text{−}}{\eta }^{\prime }\mathrm{\text{−}}G$ mixing formalism constructed in our previous work, where $G$ represents the pseudoscalar gluball. The mixing angles in this tetramixing matrix are constrained by theoretical and experimental implications from relevant hadronic processes. Especially, the angle between ${\eta }_c$ and $G$ is found to be about 11° from the measured decay widths of the ${\eta }_c$ meson. The pseudoscalar glueball mass $m_G$, the pseudoscalar densities $m_{qq,ss,cc}$, and the $U(1)$ anomaly matrix elements associated with the mixed states are solved from the anomalous Ward identities. The solution $m_G\approx 1.4\mathrm{GeV}$ obtained from the $\eta \mathrm{\text{−}}{\eta }^{\prime }\mathrm{\text{−}}G$ mixing is confirmed, while $m_{qq}$ grows to above the pion mass, and thus increases perturbative QCD predictions for the branching ratios $\mathrm{Br}(B\to {\eta }^{\prime }K)$. We then analyze the ${\eta }_c$-mixing effects on charmonium magnetic dipole transitions, and on the $B\to {\eta }^{(\prime )}{K}_S$ branching ratios and $CP$ asymmetries, which further improve the consistency between theoretical predictions and data. A predominant observation is that the ${\eta }_c$ mixing enhances the perturbative QCD predictions for $\mathrm{Br}(B\to {\eta }^{\prime }K)$ by 18%, but does not alter those for $\mathrm{Br}(B\to \eta K)$. The puzzle due to the large $\mathrm{Br}(B\to {\eta }^{\prime }K)$ data is then resolved.

We perform a chiral extrapolation of the baryon octet and decuplet masses in a relativistic formulation of chiral perturbation theory. A partial summation is assumed as implied by the use of physical baryon and meson masses in the one-loop diagrams. Upon a chiral expansion, our results are consistent with strict chiral perturbation theory at the next-to-next-to-next-to-leading order. All counter terms are correlated by a large-$N_c$ operator analysis. Our results are confronted with recent results of unquenched three-flavor lattice simulations. We adjust the parameter set to the pion-mass dependence of the nucleon and omega masses as computed by the BMW Collaboration and predict the pion-mass dependence of the remaining baryon octet and decuplet states. The current lattice simulations can be described accurately and smoothly up to pion masses of about 600 MeV. In particular, we recover the recent results of the HSC without any further adjustments.

We present a search for the rare radiative decay $W^{\pm }\to {\pi }^{\pm }\gamma$ using data corresponding to an integrated luminosity of $4.3{\mathrm{fb}}^{-1}$ of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF experiment at Fermilab. As no statistically significant signal is observed, we set a 95%-confidence-level upper limit on the relative branching fraction $\Gamma (W^{\pm }\to {\pi }^{\pm }\gamma )/\Gamma (W^{\pm }\to e^{\pm }\nu )$ at $6.4\times {10}^{-5}$, a factor of 10 improvement over the previous limit.

The momentum diffusion coefficient for heavy quarks is studied in a deconfined gluon plasma in the static approximation by investigating a correlation function of the color electric field using Monte Carlo techniques. The diffusion coefficient is extracted from the long-distance behavior of such a correlator. For temperatures $T_c<T\lesssim 2T_c$, our nonperturbative estimate of the diffusion coefficient is found to be very different from the leading-order perturbation theory and is in the right ballpark to explain the heavy quark flow seen by the PHENIX Collaboration at the RHIC experiment.

We study the zero-point energy of massless scalar and vector fields subject to spheroidal boundary conditions. For massless scalar fields and small ellipticity the zero-point energy can be found using both zeta function and Green’s function methods. The result agrees with the conjecture that the zero-point energy for a boundary remains constant under small deformations of the boundary that preserve volume (the boundary deformation conjecture), formulated in the case of an elliptic-cylindrical boundary. In the case of massless vector fields, an exact solution is not possible. We show that a zonal approximation disagrees with the result of the boundary deformation conjecture. Applying our results to the MIT bag model, we find that the zero-point energy of the bag should stabilize the bag against deformations from a spherical shape.

We consider an interacting Lifshitz field with $z=3$ in a curved spacetime. We analyze the renormalizability of the theory for interactions of the form $\lambda {\varphi }^n$, with arbitrary even $n$. We compute the running of the coupling constants both in the ultraviolet and infrared regimes. We show that the Lorentz-violating terms generate couplings to the spacetime metric that are not invariant under general coordinate transformations. These couplings are not suppressed by the scale of Lorentz violation and therefore survive at low energies. We point out that in these theories, unless the effective mass of the field is many orders of magnitude below the scale of Lorentz violation, the coupling to the four-dimensional Ricci scalar ${\xi }^{(4)}R{\varphi }^2$ does not receive large quantum corrections $\xi \gg 1$. We argue that quantum corrections involving spatial derivatives of the lapse function (which appear naturally in the so-called healthy extension of the Hořava-Lifshitz theory of gravity) are not generated unless they are already present in the bare Lagrangian.