We quantify the potential for testing modified Newtonian dynamics (MOND) with Laser Interferometer Space Antenna pathfinder, should a saddle point fly-by be incorporated into the mission. We forecast the expected signal-to-noise ratio for a variety of instrument noise models and trajectories past the saddle. For standard theoretical parameters, the signal-to-noise ratio reaches middle to high double figures even with modest assumptions about instrument performance and saddle approach. Obvious concerns, like systematics arising from Laser Interferometer Space Antenna pathfinder self-gravity, or the Newtonian background, are examined and shown not to be a problem. We also investigate the impact of a negative observational result upon the free function determining the theory. We demonstrate that, if Newton’s gravitational constant is constrained to not be renormalized by more than a few percent, only contrived MONDian free functions would survive a negative result. There are exceptions, e.g. free functions not asymptoting to 1 in the Newtonian limit, but rather diverging or asymptoting to zero (depending on their mother relativistic MONDian theory). Finally, we scan the structure of all proposed relativistic MONDian theories, and classify them with regards to their nonrelativistic limit, finding three broad cases (with a few subcases depending on the form of the free function). It is appears that only the Einstein-Aether formulation, and the subcases where the free function does not asymptote to 1 in other theories, would survive a negative result without resorting to “designer” free functions.

Hybrid inflation is a two-field model where inflation ends due to an instability. In the neighborhood of the instability point, the potential is very flat and the quantum fluctuations dominate over the classical motion of the inflaton and waterfall fields. In this article, we study this regime in the framework of stochastic inflation. We numerically solve the two coupled Langevin equations controlling the evolution of the fields and compute the probability distributions of the total number of e-folds and of the inflation exit point. Then, we discuss the physical consequences of our results, in particular, the question of how the quantum diffusion can affect the observable predictions of hybrid inflation.

We investigate monoenergetic gamma-ray signatures from annihilations of dark matter comprised of $Z^1$, the first Kaluza-Klein (KK) excitation of the $Z$ boson in a nonminimal universal extra dimensions (UED) model. The self interactions of the non-Abelian $Z^1$ gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson $B^1$, which is the standard Kaluza-Klein dark matter (KKDM) candidate. We find that the annihilation rate is indeed considerably larger for the $Z^1$ than for the $B^1$. Even though relic density calculations indicate that the mass of the $Z^1$ should be larger than the mass of the $B^1$, the predicted monoenergetic gamma fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. The realistic prospects for detection depend on the experimental energy resolution.

It has recently been shown that supersonic relative velocities between dark matter and baryonic matter can have a significant effect on formation of the first structures in the Universe. If this effect is still non-negligible during the epoch of hydrogen reionization, it generates large-scale anisotropy in the free-electron density, which gives rise to a CMB $B$ mode. We compute the $B$-mode power spectrum and find a characteristic shape with acoustic peaks at $\ell \approx 200,400,\dots$. The amplitude of this signal is a free parameter, which is related to the dependence of the ionization fraction on the relative baryon cold dark matter velocity during the epoch of reionization. However, we find that the $B$-mode signal is undetectably small for currently favored reionization models in which hydrogen is reionized promptly at $z\sim 10$, although constraints on this signal by future experiments may help constrain models in which partial reionization occurs at higher redshift, e.g., by accretion onto primordial black holes.

High-precision measurements of the temperature and polarization anisotropies of the cosmic microwave background radiation have been employed to set robust constraints on dark matter annihilation during recombination. In this work we improve and generalize these constraints to apply to energy deposition during the recombination era with arbitrary redshift dependence. Our approach also provides more rigorous and model-independent bounds on dark matter annihilation and decay scenarios. We employ principal component analysis to identify a basis of weighting functions for the energy deposition. The coefficients of these weighting functions parameterize any energy deposition model and can be constrained directly by experiment. For generic energy deposition histories that are currently allowed by WMAP 7 data, up to 3 principal component coefficients are measurable by Planck and up to 5 coefficients are measurable by an ideal cosmic variance limited experiment. For WIMP dark matter, our analysis demonstrates that the effect on the CMB is described well by a single (normalization) parameter and a universal redshift dependence for the energy deposition history. We give WMAP 7 constraints on both generic energy deposition histories and the universal WIMP case.

While the arcminute-scale cosmic microwave background (CMB) anisotropies are due to secondary effects, point sources dominate the total anisotropy power spectrum. At high frequencies the point sources are primarily in the form of dusty, star-forming galaxies. Both Herschel and Planck have recently measured the anisotropy power spectrum of cosmic infrared background (CIB) generated by dusty, star-forming galaxies from degree to subarcminute angular scales, including the nonlinear clustering of these galaxies at multipoles of 3000 to 6000 relevant to CMB secondary anisotropy studies. We scale the CIB angular power spectra to CMB frequencies and interpret the combined WMAP-7 year and arcminute-scale Atacama Cosmology Telescope and South Pole Telescope CMB power spectra measurements to constrain the Sunyaev-Zel’dovich (SZ) effects. Allowing the CIB clustering amplitude to vary, we constrain the amplitudes of thermal and kinetic SZ power spectra at 150 GHz.

Dark energy models, such as the chameleon, where the acceleration of the expansion of the Universe results from the dynamics of a scalar field coupled to matter, suffer from the potential existence of a fifth force. Three known mechanisms have been proposed to restore general relativity in the solar system and the laboratory, which are the symmetron/Damour-Polyakov effect, the Vainshtein property and the chameleon screening. Here, we propose to probe the existence of chameleons in the laboratory, considering their particle physics consequences. We envisage the resonant and nonresonant production of chameleons in the sun and their back-conversion into X-ray photons in a solar helioscope pipe such as the one used by CAST. We find that the resonant contribution is only present for a very small range of chameleon couplings to matter and occurs in extremely narrow magnetized regions in the sun. However, in the nonresonant case, chameleons are created in all available solar magnetic regions and for a very wide range of chameleon couplings to photons and matter. Such chameleons could leave the sun and be back-converted into X-ray photons above the photosphere or in the magnetic pipe of a helioscope. A detection of these X-rays would indicate the existence of chameleons. The number of produced chameleons and regenerated X-ray photons varies depending on the strength of the solar magnetic field in the production shell, the matter and photon couplings of chameleons, and the magnetic field length and magnitude inside a dipole magnet. We focus on a template model for the solar magnetic field: a constant magnetic field in a narrow shell surrounding the tachocline. The X-ray photons in a helioscope pipe obtained from back-conversion of the chameleons created inside the sun have a spectrum which is peaked in the sub-keV region, just below the actual sensitivity range of the present axion helioscopes. Nevertheless they are detectable by present-day magnetic helioscopes like CAST and Sumico, which were built originally for solar axions. We also propose a chameleon-through-a-wall experiment whereby X-ray photons from a synchroton radiation source could be converted into chameleons inside a dipole magnet, then pass a wall which is opaque to X-rays before being back-converted into X-ray photons in a second magnet downstream. We show that this could provide a direct signature for the existence of chameleon particles.

A search for an excess of muon neutrinos from dark matter annihilations in the Sun has been performed with the AMANDA-II neutrino telescope using data collected in 812 days of live time between 2001 and 2006 and 149 days of live time collected with the AMANDA-II and the 40-string configuration of IceCube during 2008 and early 2009. No excess over the expected atmospheric neutrino background has been observed. We combine these results with the previously published IceCube limits obtained with data taken during 2007 to obtain a total live time of 1065 days. We provide an upper limit at 90% confidence level on the annihilation rate of captured neutralinos in the Sun, as well as the corresponding muon flux limit at the Earth, both as functions of the neutralino mass in the range 50–5000 GeV. We also derive a limit on the neutralino-proton spin-dependent and spin-independent cross section. The limits presented here improve the previous results obtained by the collaboration between a factor of 2 and 5, as well as extending the neutralino masses probed down to 50 GeV. The spin-dependent cross section limits are the most stringent so far for neutralino masses above 200 GeV, and well below direct search results in the mass range from 50 GeV to 5 TeV.

The Nakanishi perturbative integral representation of the four-dimensional T-matrix is investigated in order to get a workable treatment for scattering states, solutions of the inhomogeneous Bethe-Salpeter Equation, in Minkowski space. The projection onto the null-plane of the four-dimensional inhomogeneous Bethe-Salpeter Equation plays a key role for devising an equation for the Nakanishi weight function (a real function), as in the homogeneous case that corresponds to bound states and it has been already studied within different frameworks. In this paper, the whole formal development is illustrated in detail and applied to a system, composed by two massive scalars interacting through the exchange of a massive scalar. The explicit expression of the scattering integral equations are also obtained in ladder approximation, and, as simple applications of our formalism, some limiting cases, like the zero-energy limit and the Wick-Cutkosky model in the continuum, are presented.

We analyze the fine-tuning in the constrained minimal supersymmetric standard model in the light of the present and expected ATLAS and CMS searches for supersymmetry. Even with $10{\mathrm{fb}}^{-1}$ of data and no discovery of supersymmetry valid regions might remain with fine-tuning less than 20. Moreover we investigate the fine-tuning price of grand unification scale Yukawa coupling relations. Considering a $2\sigma$ constraint for $(g-2{)}_{\mu }$ and fine-tuning less than 30 yields an allowed range of $y_{\tau }/y_b=[1.31,1.70]$, which points towards the alternative grand unification prediction $y_{\tau }/y_b=3/2$. Relaxing the $(g-2{)}_{\mu }$ constraint to $5\sigma$ extends the possible region to [1.02, 1.70], allowing for approximate $b-\tau$ Yukawa coupling unification.

We have analyzed the prospect of probing a nonuniversal gaugino mass model of mixed bino-Higgsino dark matter at the current 7 TeV run of LHC. It provides cosmologically compatible dark matter relic density over two broad bands of parameters, corresponding to $m_{\tilde{g}}<m_{\tilde{q}}$ and $m_{\tilde{g}}\sim m_{\tilde{q}}$. The supersymmetry spectrum of this model has two distinctive features: (i) an approximate degeneracy among the lighter chargino and neutralino masses, and (ii) an inverted mass hierarchy of squark masses. We find that these features can be exploited to obtain a viable signal up to $m_{\tilde{g}}\sim 800\mathrm{GeV}$ over both the parameter bands with an integrated luminosity $5{\mathrm{fb}}^{-1}$.

We study the reach of the Large Hadron Collider with $1{\mathrm{fb}}^{-1}$ of data at $\sqrt{s}=7\mathrm{TeV}$ for several classes of supersymmetric models with compressed mass spectra, using jets and missing transverse energy cuts like those employed by ATLAS for summer 2011 data. In the limit of extreme compression, the best limits come from signal regions that do not require more than 2 or 3 jets and that remove backgrounds by requiring more missing energy rather than a higher effective mass.

QCD lattice simulations determine hadron masses as functions of the quark masses. From the gradients of these masses and using the Feynman-Hellmann theorem the hadron sigma terms can then be determined. We use here a novel approach of keeping the singlet quark mass constant in our simulations which upon using an $SU(3)$ flavor symmetry breaking expansion gives highly constrained (i.e. few parameter) fits for hadron masses in a multiplet. This is a highly advantageous procedure for determining the hadron mass gradient as it avoids the use of delicate chiral perturbation theory. We illustrate the procedure here by estimating the light and strange sigma terms for the baryon octet.

A key problem in making precise perturbative QCD predictions is to set the proper renormalization scale of the running coupling. The extended renormalization group equations, which express the invariance of the physical observables under both the renormalization scale- and scheme-parameter transformations, provide a convenient way for estimating the scale- and scheme-dependence of the physical process. In this paper, we present a solution for the scale equation of the extended renormalization group equations at the four-loop level. Using the principle of maximum conformality (PMC)/Brodsky-Lepage-Mackenzie (BLM) scale-setting method, all nonconformal $\{{\beta }_i\}$ terms in the perturbative expansion series can be summed into the running coupling, and the resulting scale-fixed predictions are independent of the renormalization scheme. The PMC/BLM scales can be fixed order-by-order. As a useful reference, we present a systematic and scheme-independent procedure for setting PMC/BLM scales up to next-to-next-to-leading order. An explicit application for determining the scale setting of $R_{e^{+}{e}^{-}}(Q)$ up to four loops is presented. By using the world average ${\alpha }_s^{\overline{\mathrm{MS}}}(M_Z)=0.1184\pm 0.0007$, we obtain the asymptotic scale for the ’t Hooft scheme associated with the $\overline{\mathrm{MS}}$ scheme, ${\Lambda }_{\overline{\mathrm{MS}}}^{\prime tH}={245}_{-10}^{+9}\mathrm{MeV}$, and the asymptotic scale for the conventional $\overline{\mathrm{MS}}$ scheme, ${\Lambda }_{\overline{\mathrm{MS}}}={213}_{-8}^{+19}\mathrm{MeV}$.

There are good reasons that the deconfinement phase transition of pure Yang-Mills theory at finite temperature should also be reflected in the behavior of gauge-fixed gluonic correlation functions. Understanding this in detail would provide another important example of how physical information can be extracted from gauge-dependent correlations, which is not always obvious. Therefore, herein we study the behavior of the Landau-gauge gluon propagator of pure $SU(2)$ across the phase transition in $2+1$ and $3+1$ dimensions in order to assess to what extend the corresponding critical behavior is reflected in these correlations. We discuss why it should emerge from a continuum perspective and test our expectations in lattice simulations. A comparison with $SU(3)$ furthermore reveals quite clear indications for a sensitivity of the gluon propagator to the order of the transition.

Motivated by the recent observation of $CP$ violation in the charm sector by LHCb, we study direct $CP$ asymmetries in the standard model (SM) for the singly Cabibbo-suppressed two-body hadronic decays of charmed mesons using the topological-diagram approach. In this approach, the magnitude and the phase of topological weak annihilation amplitudes, which arise mainly from final-state rescattering, can be extracted from the data. Consequently, direct $CP$ asymmetry $a_{\mathrm{dir}}^{(\mathrm{tree})}$ at tree level can be reliably estimated. In general, it lies in the range ${10}^{-4}<a_{\mathrm{dir}}^{(\mathrm{tree})}<{10}^{-3}$. Short-distance QCD penguins and penguin annihilation are calculated using QCD factorization. Their effects are generally small, especially for $D\to VP$ modes. Since weak penguin annihilation receives long-distance contributions from the color-allowed tree amplitude followed by final-state rescattering, it is expected to give the dominant contribution to the direct $CP$ violation in the decays $D^0\to K^{+}{K}^{-}$ and $D^0\to {\pi }^{+}{\pi }^{-}$, in which $a_{\mathrm{dir}}^{(\mathrm{tree})}$ is absent. The maximal $\Delta a_{CP}^{\mathrm{dir}}$, the direct $CP$ asymmetry difference between the above-mentioned two modes, allowed in the SM is around $-0.25\%$, more than $2\sigma$ away from the current world average of $-(0.645\pm 0.180)\%$.

We present hadron-level predictions from the Monte Carlo generator Cascade and parton-level calculations of open $b$ quark, $b$-flavored hadron, and inclusive $b$-jet production in the framework of the $k_T$-factorization QCD approach for the LHC energies. The unintegrated gluon densities in a proton are determined using the Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation and the Kimber-Martin-Ryskin (KMR) prescription. Our predictions are compared with the first data taken by the CMS and LHCb collaborations at $\sqrt{s}=7\mathrm{TeV}$. We study the theoretical uncertainties of our calculations and investigate the effects coming from parton showers in initial and final states. The special role of initial gluon transverse momenta in description of the data is pointed out.

To see whether a heavy baryon and an antibaryon can form a bound state, the heavy baryonium, we study the two-pion exchange interaction potential between them within the heavy baryon chiral perturbation theory. The obtained potential is applied to calculate the heavy baryonium masses by solving the Schrödinger equation. We find it is true that the heavy baryonium may exist in a reasonable choice of input parameters. The uncertainties remaining in the potential and their influences on the heavy baryonium mass spectrum are discussed.

This paper reports the evaluation of the tenth-order QED contribution to the lepton $g-2$ from the gauge-invariant set of 2072 Feynman diagrams, called Set IV, which are obtained by inserting a second-order lepton vacuum-polarization loop into 518 eighth-order vertex diagrams of four-photon exchange type. The numerical evaluation is carried out by the adaptive-iterative Monte Carlo integration routine vegas using the fortran codes written by the automatic code-generating algorithm gencode$N$. Some of the numerical results are confirmed by comparison with the values of corresponding integrals that have been obtained previously by a different method. The result for the mass-independent contribution of the Set IV to the electron $g-2$ is $-7.7296(48)(\alpha /\pi {)}^5$. There is also a small mass-dependent contribution to the electron $g-2$ due to the muon loop: $-0.01136(7)(\alpha /\pi {)}^5$. The contribution of the tau-lepton loop is $-0.0000937(104)(\alpha /\pi {)}^5$. The sum of all these contributions to the electron $g-2$ is $-7.7407(49)(\alpha /\pi {)}^5$. The same set of diagrams enables us to evaluate the contributions to the muon $g-2$ from the electron loop, muon loop, and tau-lepton loop. They add up to $-46.95(17)(\alpha /\pi {)}^5$.