We discuss the possibility that the IceCube neutrino telescope might be observing the Fermi bubbles. If the bubbles discovered in gamma rays originate from accelerated protons, they should be strong emitters of high energy ($\gtrsim \mathrm{GeV}$) neutrinos. These neutrinos are detectable as showerlike or tracklike events at a ${\mathrm{Km}}^3$ neutrino observatory. For a primary cosmic ray flux with spectrum $\propto E^{-2.1}$ and cutoff energy at or above 10 PeV, the Fermi bubble flux substantially exceeds the atmospheric background, and could account for up to $\sim 4–5$ of the 28 events detected above $\sim 30\mathrm{TeV}$ at IceCube. Running the detector for $\sim 5–7$ more years should be sufficient to discover this flux at high significance. For a primary cosmic ray flux with steeper spectrum, and/or lower cutoff energy, longer running times will be required to overcome the background.

A gamma-ray excess over background has been claimed in the inner regions of the Galaxy, triggering some excitement about the possibility that the gamma rays originate from the annihilation of dark matter particles. We point out that the existence of such an excess depends on how the diffuse gamma-ray background is defined, and on the procedure employed to fit such background to observations. We demonstrate that a gamma-ray emission with spectral and morphological features closely matching the observed excess arises from a population of cosmic ray protons in the inner Galaxy, and provides proof of principle and arguments for the existence of such a population, most likely originating from local supernova remnants. Specifically, the “Galactic center excess” is readily explained by a recent cosmic ray injection burst, with an age in the 1–10 kilo-year range, while the extended inner Galaxy excess points to mega-year old injection episodes, continuous or impulsive. We conclude that it is premature to argue that there are no standard astrophysical mechanisms that can explain the excess.

Double parton distribution functions are used in the QCD description of double parton scattering. The double parton distributions evolve with hard scales through QCD evolution equations which obey nontrivial momentum and valence quark number sum rules. We describe an attempt to construct initial conditions for the evolution equations which exactly fulfill these sum rules and discuss its shortcomings. We also discuss the factorization of the double parton distributions into a product of two single parton distribution functions at small values of the parton momentum fractions.

We consider semi-inclusive $\mathrm{diphoton}+\mathrm{jet}$ and inclusive diphoton production in high-energy proton-nucleus collisions, treating the target nucleus as a color-glass condensate and the projectile proton in the parton model. We obtain the prompt diphoton production cross section in terms of fragmentation and direct contributions. The fragmentation part is given in terms of single-photon and double-photon fragmentation functions. We study prompt, direct, and fragmentation diphoton correlations in $\mathrm{p}+\mathrm{p}$ and $\mathrm{p}+\mathrm{A}$ collisions at the LHC and show that at low values of transverse momenta of the produced photon pair these correlations are sensitive to saturation effects. We show that back-to-back (de)correlations in prompt diphoton production are stronger in the fragmentation part than in the direct one.

We discuss the $\beta$-deformation of ${\mathrm{AdS}}_5\times S^5$ which incorporates the $SL(2,\mathbb{R})$ symmetry of the type IIB theory. The axion-dilaton is identified with a two-torus from an 11-dimensional viewpoint. We consider the null geodesic with equal component angular momenta to take the Penrose limit of the deformed ${\mathrm{AdS}}_5\times S^5$. We study the bosonic part of the string sigma model and the spectrum of the string in the $pp$-wave background.

The methods of nonlinear realizations have proven to be powerful in studying the low-energy physics resulting from spontaneously broken internal and spacetime symmetries. In this paper, we reconsider how these techniques may be applied to the case of spontaneously broken gauge theories, concentrating on Yang-Mills theories. We find that coset methods faithfully reproduce the description of low-energy physics in terms of massive gauge bosons and discover that the Stückelberg replacement commonly employed when treating massive gauge theories arises in a natural manner. Uses of the methods are considered in various contexts, including generalizations to $p$-form gauge fields. We briefly discuss potential applications of the techniques to theories of massive gravity and their possible interpretation as a Higgs phase of general relativity.

We report on a series of new solutions to five-dimensional minimal supergravity. Our method applies to space-times with two commuting Killing symmetries and consists in combining dimensional reduction on two-spaces of constant curvature with reduction on a two-torus. The first gives rise to various generalized Bertotti-Robinson solutions supported by electric and magnetic fluxes, which presumably describe the near-horizon regions of black holes and black rings (strings). The second provides generating techniques based on $U$ duality of the corresponding three-dimensional sigma model. We identify duality transformations relating the above solutions to asymptotically flat ones and obtain new globally regular dyonic solitons. Some new extremal asymptotically flat multicenter solutions are constructed too. We also show that geodesic solutions of three-dimensional sigma models passing through the same target space point generically split into disjoint classes which cannot be related by the isotropy subgroup of $U$ duality.

We consider a self-gravitating system containing a globally timelike Killing vector and a nonlinear Born-Infeld electromagnetic field and scalar fields. We prove that under certain boundary conditions (asymptotically flat/anti–de Sitter) there cannot be any nontrivial field configurations in the spacetime. To explore nontrivial solutions, one should break any of the conditions we imposed. The case with another type of nonlinear electromagnetic field is also analyzed, and similar conclusions have been obtained under certain conditions.

We study quantum gravitational perturbations in the static patch of de Sitter space. In particular, we determine the symplectic inner product of these perturbations and use it to write down the graviton two-point function in the state analogous to the Bunch-Davies vacuum in a certain gauge. We find this two-point function to be infrared-finite and time-translation invariant.

We consider spherically symmetric spacetimes sourced by a fluid with pressure anisotropy in the radial direction. We use gauge-invariant perturbation theory to study the stability of this class of spacetimes under axial perturbations. We apply our results to three diverse examples. Two examples arise as endpoints of collapse of a ball of fluid—one describes a well-behaved stellar interior, and the other has a naked singularity. We prove the stability of the stellar interior both with respect to Dirichlet and quasinormal mode boundary conditions on the perturbation. Surprisingly, the naked singularity is also stable under axial perturbations. Last, we take the example of anisotropic cosmology to show that, in this case, the relevant perturbations are those in which the direction of anisotropy is also perturbed.

We construct empirical models of the diffuse gamma-ray background toward the Galactic Center. Including all known point sources and a template of emission associated with interactions of cosmic rays with molecular gas, we show that the extended emission observed previously in the Fermi Large Area Telescope data toward the Galactic Center is detected at high significance for all permutations of the diffuse model components. However, we find that the fluxes and spectra of the sources in our model change significantly depending on the background model. In particular, the spectrum of the central Sgr A* source is less steep than in previous works and the recovered spectrum of the extended emission has large systematic uncertainties, especially at lower energies. If the extended emission is interpreted to be due to dark matter annihilation, we find annihilation into pure $b$-quark and $\tau$-lepton channels to be statistically equivalent goodness of fits. In the case of the pure $b$-quark channel, we find a dark matter mass of $39.4(\genfrac{}{}{0ex}{}{+3.7}{-2.9}\text{stat})(\pm 7.9\mathrm{sys})\mathrm{GeV}$, while a pure ${\tau }^{+}{\tau }^{-}$-channel case has an estimated dark matter mass of $9.43(\genfrac{}{}{0ex}{}{+0.63}{-0.52}\text{stat})(\pm 1.2\mathrm{sys})\mathrm{GeV}$. Alternatively, if the extended emission is interpreted to be astrophysical in origin such as due to unresolved millisecond pulsars, we obtain strong bounds on dark matter annihilation, although systematic uncertainties due to the dependence on the background models are significant.

The amplitude for Higgs boson decay into two photons in a homogeneous and time-independent magnetic field is investigated by proper-time regularization in a gauge-invariant manner and is found to be singular at large field values. The singularity is caused by the component of the charged vector boson field that is tachyonic in a strong magnetic field. Also, tools for the computation of the amplitude in a more general electromagnetic background are developed.

It has been pointed out recently that current experiments still allow for a two Higgs doublet model where the $hb\overline{b}$ coupling ($k_D{m}_b/v$) is negative; a sign opposite to that of the Standard Model. Due to the importance of delayed decoupling in the $h{H}^{+}{H}^{-}$ coupling, $h\to \gamma \gamma$ improved measurements will have a strong impact on this issue. For the same reason, measurements or even bounds on $h\to Z\gamma$ are potentially interesting. In this article, we revisit this problem, highlighting the crucial importance of $h\to VV$, which can be understood with simple arguments. We show that the impacts on $k_D<0$ models of both $h\to b\overline{b}$ and $h\to {\tau }^{+}{\tau }^{-}$ are very sensitive to input values for the gluon fusion production mechanism; in contrast, $h\to \gamma \gamma$ and $h\to Z\gamma$ are not. We also inquire if the search for $h\to Z\gamma$ and its interplay with $h\to \gamma \gamma$ will impact the sign of the $hb\overline{b}$ coupling. Finally, we study these issues in the context of the flipped two Higgs doublet model.

We present an analysis of nonperturbative contributions to the transverse momentum distribution of $Z/{\gamma }^{*}$ bosons produced at hadron colliders. The new data on the angular distribution ${\varphi }_{\eta }^{*}$ of Drell-Yan pairs measured at the Tevatron are shown to be in excellent agreement with a perturbative QCD prediction based on the Collins-Soper-Sterman (CSS) resummation formalism at next-to-next-to-leading logarithmic (NNLL) accuracy. Using these data, we determine the nonperturbative component of the CSS resummed cross section and estimate its dependence on arbitrary resummation scales and other factors. With the scale dependence included at the NNLL level, a significant nonperturbative component is needed to describe the angular data.

An intriguing opposite sign of the $CP$-violating asymmetry from that expected within the Standard Model was recently measured in the tau decay modes ${\tau }^{\pm }\to K_s{\pi }^{\pm }{\stackrel{(-)}{\nu }}_{\tau }$ by the BABAR collaboration. If this result is confirmed with higher precision, the observed decay rate asymmetry $A_{CP}$ can only arise from some nonstandard interactions occurring possibly in both the hadronic as well as in the leptonic sectors. We illustrate that, while a simple charged scalar interaction cannot yield this rate asymmetry, it will be possible to generate this in the presence of a tensor interaction. Parametrizing the strength and weak phase of this nonstandard interaction contribution, the observed branching ratio and the decay-rate $CP$ asymmetry for the particular mode ${\tau }^{\pm }\to K_s{\pi }^{\pm }{\stackrel{(-)}{\nu }}_{\tau }$ are used to determine the $CP$-violating weak phase and the coupling of a tensorial interaction that can give a consistent sign and magnitude of the asymmetry.

New heavy leptons with standard model gauge couplings have well-determined cross sections for pair production. A standard pattern of mass mixing implies that the most likely decays are ${\tau }^{\prime }\to W{\nu }^{\prime }$ and ${\nu }^{\prime }\to W\tau$. Interestingly there have been no direct searches for heavy leptons with these decays at the LHC. However comparison with several multilepton searches allows us to set new limits on the heavy lepton masses. Three observed excesses in the signal regions prevent us from setting stronger limits.

We present a significantly improved determination of the Bjorken sum for $0.6\le Q^2\le 4.8{\mathrm{GeV}}^2$ using precise new $g_1^p$ and $g_1^d$ data taken with the CLAS detector at Jefferson Lab. A higher-twist analysis of the $Q^2$ dependence of the Bjorken sum yields the twist-4 coefficient $f_2^{p-n}=-0.064\pm 0.009{\pm }_{0.036}^{0.032}$. This leads to the color polarizabilities ${\chi }_E^{p-n}=-0.032\pm 0.024$ and ${\chi }_B^{p-n}=0.032\pm 0.013$. The strong force coupling is determined to be ${\alpha }_s^{\overline{\mathrm{MS}}}(M_Z^2)=0.1123\pm 0.0061$, which has an uncertainty a factor of 1.5 smaller than earlier estimates using polarized deep inelastic scattering (DIS) data. This improvement makes the comparison between ${\alpha }_s$ extracted from polarized DIS and other techniques a valuable test of QCD.

Extremely weakly interacting particles like the gravitino may be stable enough on cosmological time scales to constitute a good dark matter candidate even in the presence of $R$-parity violation. We consider the possibility that the recently identified 3.5 keV x-ray line can be generated in light gravitino decays to neutrinos and photons. We find that this is indeed possible in loop processes induced by trilinear lepton-number-violating couplings. We show that in order to avoid overproduction of gravitinos, the reheating temperature has to be at most around 100 GeV to 1 TeV. Finally we briefly discuss associated LHC phenomenology due to a relatively light gluino and multijet/multilepton events from $R$-parity-violating decays of neutralinos.