We study the complex scalar loop corrections to the boundary-boundary gauge two-point function in pure AdS space in Poincare coordinates, in the presence of boundary quadratic perturbations to the scalar. These perturbations correspond to double-trace perturbations in the dual CFT and modify the boundary conditions of the bulk scalars in AdS. We find that, in addition to the usual UV divergences, the one-loop calculation suffers from a divergence originating in the limit as the loop vertices approach the AdS horizon. We show that this type of divergence is independent of the boundary coupling; making use of this we extract the finite relative variation of the imaginary part of the loop via Cutkosky rules as the boundary perturbation varies. Applying our methods to compute the effects of a time-dependent impurity to the conductivities using the replica trick in AdS/CFT, we find that generally an IR-relevant disorder reduces the conductivity and that in the extreme low frequency limit the correction due to the impurities overwhelms the planar CFT result even though it is supposedly $1/N^2$ suppressed. We also comment on the more physical scenario of a time-independent impurity.

We investigate the dark matter and the cosmological baryon asymmetry in a simple theory where baryon ($B$) and lepton ($L$) number are local gauge symmetries that are spontaneously broken. In this model, the cold dark matter candidate is the lightest new field with baryon number and its stability is an automatic consequence of the gauge symmetry. Dark matter annihilation is either through a leptophobic gauge boson whose mass must be below a TeV or through the Higgs boson. Since the mass of the leptophobic gauge boson has to be below the TeV scale, one finds that in the first scenario there is a lower bound on the elastic cross section of about $5\times {10}^{-46}{\mathrm{cm}}^2$. Even though baryon number is gauged and not spontaneously broken until the weak scale, a cosmologically acceptable baryon excess is possible. There can be a tension between achieving both the measured baryon excess and the dark matter density.

Dark matter density profiles based upon $\Lambda \mathrm{CDM}$ cosmology motivate an ansatz velocity distribution function with fewer high-velocity particles than the Maxwell-Boltzmann distribution or proposed variants. The high-velocity tail of the distribution is determined by the outer slope of the dark matter halo—the large radius behavior of the Galactic dark matter density. $N$-body simulations of Galactic halos reproduce the high-velocity behavior of this ansatz. Predictions for direct detection rates are dramatically affected for models where the threshold scattering velocity is within 30% of the escape velocity.

We extend the Abbott-Deser-Tekin procedure of defining conserved quantities of asymptotically constant-curvature spacetimes, and give an analogous expression for the conserved charges of geometries that are solutions of quadratic curvature gravity models in generic $D$ dimensions and that have arbitrary asymptotes possessing at least one Killing isometry. We show that the resulting charge expression correctly reduces to its counterpart when the background is taken to be a space of constant curvature and, moreover, is background gauge invariant. As applications, we compute and comment on the energies of two specific examples: the three-dimensional Lifshitz black hole and a five-dimensional companion of the first, whose energy has never been calculated before.

The gravitational couplings of matter are studied in the presence of Lorentz and $CPT$ violation. At leading order in the coefficients for Lorentz violation, the relativistic quantum Hamiltonian is derived from the gravitationally coupled minimal standard-model extension. For spin-independent effects, the nonrelativistic quantum Hamiltonian and the classical dynamics for test and source bodies are obtained. A systematic perturbative method is developed to treat small metric and coefficient fluctuations about a Lorentz-violating and Minkowski background. The post-Newtonian metric and the trajectory of a test body freely falling under gravity in the presence of Lorentz violation are established. An illustrative example is presented for a bumblebee model. The general methodology is used to identify observable signals of Lorentz and $CPT$ violation in a variety of gravitational experiments and observations, including gravimeter measurements, laboratory and satellite tests of the weak equivalence principle, antimatter studies, solar-system observations, and investigations of the gravitational properties of light. Numerous sensitivities to coefficients for Lorentz violation can be achieved in existing or near-future experiments at the level of parts in ${10}^3$ down to parts in ${10}^{15}$. Certain coefficients are uniquely detectable in gravitational searches and remain unmeasured to date.

Multiple Parton Interactions are the tool to obtain information on the correlations between partons in the hadron structure. Partons may be correlated in all degrees of freedom and all different correlation terms contribute to the cross section. The contributions due to the different parton flavors can be isolated, at least to some extent, by selecting properly the final state. In the case of high energy proton-proton collisions, the effects of correlations in the transverse coordinates and in fractional momenta are, on the contrary, unavoidably mixed in the final observables. The standard way to quantify the strength of double parton interactions is by the value of the effective cross section and a small value of the effective cross section may be originated both by the relatively short transverse distance between the pairs of partons undergoing the double interaction and by a large dispersion of the distribution in multiplicity of the multiparton distributions. The aim of the present paper is to show how the effects of longitudinal and transverse correlations may be disentangled by taking into account the additional information provided by double parton interactions in high energy proton-deuteron collisions.

The one-loop contribution of the excited Kaluza-Klein (KK) modes of the $S{U}_L(2)$ gauge group on the off-shell $W^{-}{W}^{+}\gamma$ and $W^{-}{W}^{+}Z$ vertices is calculated in the context of a pure Yang-Mills theory in five dimensions and its phenomenological implications discussed. The use of a gauge-fixing procedure for the excited KK modes that is covariant under the standard gauge transformations of the $S{U}_L(2)$ group is stressed. A gauge-fixing term and the Faddeev-Popov ghost sector for the KK gauge modes that are separately invariant under the standard gauge transformations of $S{U}_L(2)$ are presented. It is shown that the one-loop contributions of the KK modes to the off-shell $W^{-}{W}^{+}\gamma$ and $W^{-}{W}^{+}Z$ vertices are free of ultraviolet divergences and well-behaved at high energies. It is found that for a size of the fifth dimension of $R^{-1}\sim 1\mathrm{TeV}$, the one-loop contribution of the KK modes to these vertices is about 1 order of magnitude lower than the corresponding standard model radiative correction. This contribution is similar to the one estimated for new gauge bosons contributions in other contexts. Tree-level effects on these vertices induced by operators of higher canonical dimension are also investigated. It is found that these effects are lower than those generated at the one-loop order by the KK gauge modes.

The discovery of charged Higgs bosons is of particular importance, since their existence is predicted by supersymmetry and they are absent in the standard model (SM). If the charged Higgs bosons are too heavy to be produced in pairs at future linear colliders, single production associated with a top and a bottom quark is enhanced in parts of the parameter space. We present the next-to-leading-order calculation in supersymmetric QCD within the minimal supersymmetric SM, completing a previous calculation of the SM-QCD corrections. In addition to the usual approach to perform the loop integration analytically, we apply a numerical approach based on the Bernstein-Tkachov theorem. In this framework, we avoid some of the generic problems connected with the analytical method.

Using data from the $B$ factories and the Tevatron, we perform tests of how well nonleptonic $B$ decays of the kind $B\to D_{(s)}^{(*)}P$, where $P$ is a pion or kaon, are described within the factorization framework. We find that factorization works well—as is theoretically expected—for color-allowed, tree-diagram-like topologies. Moreover, also exchange topologies, which have a nonfactorizable character, do not show any anomalous behavior. We discuss also isospin triangles between the $B\to D^{(*)}\pi$ decay amplitudes, and determine the corresponding amplitudes in the complex plane, which show a significant enhancement of the color-suppressed tree contribution with respect to the factorization picture. Using data for $B\to D^{(*)}K$ decays, we determine $SU(3)$-breaking effects and cannot resolve any nonfactorizable $SU(3)$-breaking corrections larger than $\sim 5\%$. In view of these results, we point out that a comparison between the ${\overline{B}}_d^0\to D^{+}{\pi }^{-}$ and ${\overline{B}}_s^0\to D_s^{+}{\pi }^{-}$ decays offers an interesting new determination of $f_d/f_s$. Using CDF data, we obtain the most precise value of this ratio at CDF, and discuss the prospects for a corresponding measurement at LHCb.

The measurement of the ${\eta }_b$ mass, together with a QCD result for the hyperfine splitting $E_{\mathrm{HFS}}=M_{{\rm Y}(1S)}-M_{{\eta }_b}$, allows us to determine the strong coupling constant ${\alpha }_s$ at a low energy scale. The result ${\alpha }_s(M_{{\rm Y}(1S)})=0.197\pm 0.002{|}_{\Delta E_{\mathrm{HFS}}^{\exp }}\pm 0.002{|}_{\mathrm{scheme}}\pm 0.002{|}_{\delta ⟨G^2⟩}\pm 0.006{|}_{\delta m_b}\pm 0.005{|}_{\mathrm{ho}}$, ${\alpha }_s(M_{Z^0})=0.124\pm 0.001{|}_{\Delta E_{\mathrm{HFS}}^{\exp }}\pm 0.001{|}_{\mathrm{scheme}}\pm 0.001{|}_{\delta ⟨G^2⟩}\pm 0.003{|}_{\delta m_b}\pm 0.002{|}_{\mathrm{ho}}$ is compatible with the current world average of ${\alpha }_s$ reported by the Particle Data Group, and shows that the experimental lowest-lying $\overline{b}b$ hyperfine splitting can be reproduced in terms of a perturbative and nonperturbative QCD contribution.

We propose a supersymmetric $A_4\times SU(5)$ model of quasidegenerate neutrinos which predicts the effective neutrino mass $m_{ee}$ relevant for neutrinoless double beta decay to be proportional to the neutrino mass scale, thereby allowing its determination approximately independently of unknown Majorana phases. Such a natural quasidegeneracy is achieved by using $A_4$ family symmetry (as an example of a non-Abelian family symmetry with real triplet representations) to enforce a contribution to the neutrino mass matrix proportional to the identity. Tribimaximal neutrino mixing as well as quark $CP$ violation with $\alpha \approx 90°$ and a leptonic $CP$ phase ${\delta }_{\mathrm{MNS}}\approx 90°$ arise from the breaking of the $A_4$ family symmetry by the vacuum expectation values of four “flavon” fields pointing in specific postulated directions in flavor space.

The innermost stable circular orbit (ISCO) delimits the transition from circular orbits to those that plunge into a black hole. In the test-mass limit, well-defined ISCO conditions exist for the Kerr and Schwarzschild spacetimes. In the finite-mass case, there are a large variety of ways to define an ISCO in a post-Newtonian (PN) context. Here I generalize the gauge-invariant ISCO condition of Blanchet and Iyer [Classical Quantum Gravity 20, 755 (2003)] to the case of spinning (nonprecessing) binaries. The Blanchet-Iyer ISCO condition has two desirable and unexpected properties: (1) it exactly reproduces the Schwarzschild ISCO in the test-mass limit, and (2) it accurately approximates the recently calculated shift in the Schwarzschild ISCO frequency due to the conservative-piece of the gravitational self-force [L. Barack and N. Sago, Phys. Rev. Lett. 102, 191101 (2009)]. The generalization of this ISCO condition to spinning binaries has the property that it also exactly reproduces the Kerr ISCO in the test-mass limit (up to the order at which PN spin corrections are currently known). The shift in the ISCO due to the spin of the test-particle is also calculated. Remarkably, the gauge-invariant PN ISCO condition exactly reproduces the ISCO shift predicted by the Papapetrou equations for a fully relativistic spinning particle. It is surprising that an analysis of the stability of the standard PN equations of motion is able (without any form of “resummation”) to accurately describe strong-field effects of the Kerr spacetime. The ISCO frequency shift due to the conservative self-force in Kerr is also calculated from this new ISCO condition, as well as from the effective-one-body Hamiltonian of Barausse and Buonanno [Phys. Rev. D 81, 084024 (2010)]. These results serve as a useful point of comparison for future gravitational self-force calculations in the Kerr spacetime.

Barack and Sago [Phys. Rev. Lett. 102, 191101 (2009)] have recently computed the shift of the innermost stable circular orbit (ISCO) of the Schwarzschild spacetime due to the conservative self-force that arises from the finite-mass of an orbiting test-particle. This calculation of the ISCO shift is one of the first concrete results of the self-force program, and provides an exact (fully relativistic) point of comparison with approximate post-Newtonian (PN) computations of the ISCO. Here this exact ISCO shift is compared with nearly all known PN-based methods. These include both “nonresummed” and “resummed” approaches (the latter reproduce the test-particle limit by construction). The best agreement with the exact (Barack-Sago) result is found when the pseudo-4PN coefficient of the effective-one-body (EOB) metric is fit to numerical relativity simulations. However, if one considers uncalibrated methods based only on the currently known 3PN-order conservative dynamics, the best agreement is found from the gauge-invariant ISCO condition of Blanchet and Iyer [Classical Quantum Gravity 20, 755 (2003)], which relies only on the (nonresummed) 3PN equations of motion. This method reproduces the exact test-particle limit without any resummation. A comparison of PN methods with the ISCO in the equal-mass case (computed via sequences of numerical relativity initial-data sets) is also performed. Here a (different) nonresummed method also performs very well (as was previously shown). These results suggest that the EOB approach—while exactly incorporating the conservative test-particle dynamics and having several other important advantages—does not (in the absence of calibration) incorporate conservative self-force effects more accurately than standard PN methods. I also consider how the conservative self-force ISCO shift, combined in some cases with numerical relativity computations of the ISCO, can be used to constrain our knowledge of (1) the EOB effective metric, (2) phenomenological inspiral-merger-ringdown templates, and (3) 4PN- and 5PN-order terms in the PN orbital energy. These constraints could help in constructing better gravitational-wave templates. Lastly, I suggest a new method to calibrate unknown PN terms in inspiral templates using numerical-relativity calculations.

We study the prospects for detecting the annihilation products of dark matter (DM) in the framework of the two highest-resolution numerical simulations currently available, i.e., Via Lactea II and Aquarius. We propose a strategy to determine the shape and size of the region around the Galactic center that maximizes the probability of observing a DM signal, and we show that, although the predicted flux can differ by a factor of 10 for a given DM candidate in the two simulation setups, the search strategy remains actually unchanged, since it relies on the angular profile of the annihilation flux, not on its normalization. We present mock $\gamma$-ray maps that keep into account the diffuse emissions produced by unresolved halos in the Galaxy, and we show that, in an optimistic DM scenario, a few individual clumps can be resolved above the background with the Fermi-LAT. Finally, we calculate the energy-dependent boost factors for positrons and antiprotons and show that they are always of $\mathcal{O}(1)$, and, therefore, they cannot lead to the large enhancements of the antimatter fluxes required to explain the recent PAMELA, ATIC, Fermi, and HESS data. Still, we show that the annihilation of 100 GeV weakly interacting massive particles into charged lepton pairs may contribute significantly to the positron budget.

We utilize top polarization in the process $e^{+}{e}^{-}\to t\overline{t}$ at the International Linear Collider (ILC) with transverse beam polarization to probe interactions of the scalar and tensor type beyond the standard model and to disentangle their individual contributions. Ninety percent confidence level limits on the interactions with realistic integrated luminosity are presented and are found to improve by an order of magnitude compared to the case when the spin of the top quark is not measured. Sensitivities of the order of a few times ${10}^{-3}{\mathrm{TeV}}^{-2}$ for real and imaginary parts of both scalar and tensor couplings at $\sqrt{s}=500$ and 800 GeV with an integrated luminosity of $500{\mathrm{fb}}^{-1}$ and completely polarized beams are shown to be possible. A powerful model-independent framework for inclusive measurements is employed to describe the spin-momentum correlations, and their $C$, $P$, and $T$ properties are presented in a technical appendix.

Recent work shows not only the necessity of a $1/N_c$ expansion to explain the observed mass spectrum of the lightest baryons, but also that at least two distinct large $N_c$ expansions, in which quarks transform under either the color-fundamental or the two-index antisymmetric representation of $\mathrm{SU}(N_c)$, work comparably well. Here we show that the baryon magnetic moments do not support this ambivalence; they strongly prefer the color-fundamental $1/N_c$ expansion, providing experimental evidence that nature decisively distinguishes among $1/N_c$ expansions for this observable.

In this paper, by deriving the expressions for double-lepton polarization asymmetries for $B$ to a scalar meson transition in SM and SM4 and considering the corresponding uncertainties in SM we investigate the indirect effects of the fourth generation of quarks on such asymmetries in the $B\to K_0^{*}(1430){\ell }^{+}{\ell }^{-}$ decay. We also compare these asymmetries with those of $B\to K{\ell }^{+}{\ell }^{-}$ decay and find out that most of these asymmetries behave similarly to the corresponding asymmetries for $B\to K{\ell }^{+}{\ell }^{-}$ decay. We finally show that in the $\mu$ channel all asymmetries, except $⟨P_{LL}⟩$, and in $\tau$ channel only $⟨P_{LN}⟩$ can manifest the influence of the fourth generation at the minimum value of $m_{t^{\prime }}$ around 200 GeV. In addition, it is shown that for the $\tau$ channel the asymmetries such as $⟨P_{LL}⟩$, $⟨P_{NN}⟩$, and $⟨P_{TT}⟩$ can indicate the effect of such new physics at $m_{t^{\prime }}\ge 300\mathrm{GeV}$. Hence, the $B\to K_0^{*}(1430){\ell }^{+}{\ell }^{-}$ decay is a valuable tool for probing new physics beyond SM, especially in the indirect searches of the fourth generation of quarks $(t^{\prime },b^{\prime })$ via its manifestations in loop diagrams.

In the standard model the hypercharges of quarks and leptons are not determined by the gauge group $SU(3{)}_c\times SU(2{)}_{\mathrm{L}}\times U(1{)}_{\mathrm{Y}}$ alone. We show that, if we choose the semidirect product group $[SU(3{)}_c\times SU(2{)}_{\mathrm{L}}]⋊U(1{)}_{\mathrm{Y}}$ as its gauge group, the hyperchages are settled to be $n/6$ $\mathrm{mod}\mathbb{Z}(n=0,1,3,4)$. In addition, the conditions for gauge-anomaly cancellation give strong constraints. As a result, the ratios of the hypercharges are uniquely determined and the gravitational anomaly is automatically canceled. The standard charge assignment to quarks and leptons can be properly reproduced. For exotic matter fields their hypercharges are also discussed.

Technidilaton (TD) was proposed long ago in the technicolor near criticality/conformality. To reveal the critical behavior of TD, we explicitly compute the nonperturbative contributions to the scale anomaly $⟨{\theta }_{\mu }^{\mu }⟩$ and to the technigluon condensate $⟨\alpha G_{\mu \nu }^2⟩$, which are generated by the dynamical mass $m$ of the technifermions. Our computation is based on the (improved) ladder Schwinger-Dyson equation, with the gauge coupling $\alpha$ replaced by the two-loop running coupling $\alpha (\mu )$ having the Caswell-Banks-Zaks infrared fixed point ${\alpha }_{*}$: $\alpha (\mu )\simeq \alpha ={\alpha }_{*}$ for the infrared region $m<\mu <{\Lambda }_{\mathrm{TC}}$, where ${\Lambda }_{\mathrm{TC}}$ is the intrinsic scale (analogue of ${\Lambda }_{\mathrm{QCD}}$ of QCD) relevant to the perturbative scale anomaly. We find that $-⟨{\theta }_{\mu }^{\mu }⟩/m^4\to \mathrm{const}\ne 0$ and $⟨\alpha G_{\mu \nu }^2⟩/m^4\to (\alpha /{\alpha }_{\mathrm{cr}}-1{)}^{-3/2}\to \infty$ in the criticality limit $m/{\Lambda }_{\mathrm{TC}}\sim \exp (-\pi /(\alpha /{\alpha }_{\mathrm{cr}}-1{)}^{1/2})\to 0$ ($\alpha ={\alpha }_{*}\searrow {\alpha }_{\mathrm{cr}}$, or $N_f\nearrow N_f^{\mathrm{cr}}$) (“conformal edge”). Our result precisely reproduces the formal identity $⟨{\theta }_{\mu }^{\mu }⟩=(\beta (\alpha )/4{\alpha }^2)⟨\alpha G_{\mu \nu }^2⟩$, where $\beta (\alpha )={\Lambda }_{\mathrm{TC}}\frac{\partial \alpha }{\partial {\Lambda }_{\mathrm{TC}}}=-(2{\alpha }_{\mathrm{cr}}/\pi )·(\alpha /{\alpha }_{\mathrm{cr}}-1{)}^{3/2}$ is the nonperturbative beta function corresponding to the above essential singularity scaling of $m/{\Lambda }_{\mathrm{TC}}$. Accordingly, the partially conserved dilatation current implies $(M_{\mathrm{TD}}/m{)}^2(F_{\mathrm{TD}}/m{)}^2=-4⟨{\theta }_{\mu }^{\mu }⟩/m^4\to \mathrm{const}\ne 0$ at criticality limit, where $M_{\mathrm{TD}}$ is the mass of TD and $F_{\mathrm{TD}}$ the decay constant of TD. We thus conclude that at criticality limit the TD could become a “true (massless) Nambu-Goldstone boson” $M_{\mathrm{TD}}/m\to 0$, only when $m/F_{\mathrm{TD}}\to 0$, namely, getting decoupled, as was the case of “holographic technidilaton” of Haba-Matsuzaki-Yamawaki. The decoupled TD can be a candidate of dark matter.

Three-quark nucleon interpolating fields in QCD have well-defined $S{U}_L(3)\times S{U}_R(3)$ and $U_A(1)$ chiral transformation properties, viz. $[(\mathbf{6},\mathbf{3})\oplus (\mathbf{3},\mathbf{6})]$, $[(\mathbf{3},\overline{\mathbf{3}})\oplus (\overline{\mathbf{3}},\mathbf{3})]$, $[(\mathbf{8},\mathbf{1})\oplus (\mathbf{1},\mathbf{8})]$, and their mirror images; see [H. X. Chen, V. Dmitrašinović, A. Hosaka, K. Nagata, and S. L. Zhu, Phys. Rev. D 78, 054021 (2008)]. It has been shown (phenomenologically) in [H. X. Chen, V. Dmitrašinović, and A. Hosaka, Phys. Rev. D 81, 054002 (2010)] that mixing of the $[(\mathbf{6},\mathbf{3})\oplus (\mathbf{3},\mathbf{6})]$ chiral multiplet with one ordinary (naive) and one mirror field belonging to the $[(\mathbf{3},\overline{\mathbf{3}})\oplus (\overline{\mathbf{3}},\mathbf{3})]$, $[(\mathbf{8},\mathbf{1})\oplus (\mathbf{1},\mathbf{8})]$ multiplets can be used to fit the values of the isovector ($g_A^{(3)}$) and the flavor-singlet (isoscalar) axial coupling ($g_A^{(0)}$) of the nucleon and then predict the axial $F$ and $D$ coefficients, or vice versa, in reasonable agreement with experiment. In an attempt to derive such mixing from an effective Lagrangian, we construct all $S{U}_L(3)\times S{U}_R(3)$ chirally invariant nonderivative one-meson-baryon interactions and then calculate the mixing angles in terms of baryons’ masses. It turns out that there are (strong) selection rules: for example, there is only one nonderivative chirally symmetric interaction between $J=\frac{1}{2}$ fields belonging to the $[(\mathbf{6},\mathbf{3})\oplus (\mathbf{3},\mathbf{6})]$ and the $[(\mathbf{3},\overline{\mathbf{3}})\oplus (\overline{\mathbf{3}},\mathbf{3})]$ chiral multiplets, that is also $U_A(1)$ symmetric. We also study the chiral interactions of the $[(\mathbf{3},\overline{\mathbf{3}})\oplus (\overline{\mathbf{3}},\mathbf{3})]$ and $[(\mathbf{8},\mathbf{1})\oplus (\mathbf{1},\mathbf{8})]$ nucleon fields. Again, there are selection rules that allow only one off-diagonal nonderivative chiral $S{U}_L(3)\times S{U}_R(3)$ interaction of this type, that also explicitly breaks the $U_A(1)$ symmetry. We use this interaction to calculate the corresponding mixing angles in terms of baryon masses and fit two lowest-lying observed nucleon (resonance) masses, thus predicting the third ($J=\frac{1}{2}$, $I=\frac{3}{2}$) $\Delta$ resonance, as well as one or two flavor-singlet $\Lambda$ hyperon(s), depending on the type of mixing. The effective chiral Lagrangians derived here may be applied to high density matter calculations.