We show how the symmetry breaking pattern of the simplest little Higgs model, and that of the smallest moose model that incorporates an approximate custodial SU(2), can be realized through the condensation of strongly coupled fermions. In each case a custodial SU(2) symmetry of the new strong dynamics limits the sizes of corrections to precision electroweak observables. In the case of the simplest little Higgs, there are no new light states beyond those present in the original model. However, our realization of the symmetry breaking pattern of the moose model predicts an additional scalar field with mass of order a TeV or higher that has exactly the same quantum numbers as the standard model Higgs and which decays primarily to third generation quarks.

We study the complementarity between the indirect detection of dark matter with $\gamma$-rays in H.E.S.S. and the supersymmetry searches with ATLAS at the Large Hadron Collider (LHC) in the focus point region within the mSUGRA framework. The sensitivity of the central telescope of the H.E.S.S. II experiment with an energy threshold of $\sim 20\mathrm{GeV}$ is investigated. We show that the detection of $\gamma$-ray fluxes of $\mathcal{O}({10}^{-12}){\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ with H.E.S.S. II covers a substantial part of the focus point region which may be more difficult for LHC experiments. Despite the presence of multi-TeV scalars, we show that LHC will be sensitive to a complementary part of this region through three-body next-to-lightest supersymmetric particle leptonic decays. This interesting complementarity between H.E.S.S. II and LHC searches is further highlighted in terms of the gluino mass and the two lightest neutralino mass difference.

We discuss the properties of the collective modes of a system composed by a thermalized quark-gluon plasma traversed by a relativistic jet of partons. The transport equations obeyed by the components of the plasma and of the jet are studied in the Vlasov approximation. Assuming that the partons in the jet can be described with a tsunamilike distribution function we derive the expressions of the dispersion law of the collective modes. Then the behavior of the unstable gauge modes of the system is analyzed for various values of the velocity of the jet, of the momentum of the collective modes and of the angle between these two quantities. We find that the most unstable modes are those with momentum orthogonal to the velocity of the jet and that these instabilities appear when the velocity of the jet is higher than a threshold value, which depends on the plasma and jet frequencies. The results obtained within the Vlasov approximation are compared with the corresponding results obtained using a chromohydrodynamical approach. The effect we discuss here suggests a possible collective mechanism for the description of the jet quenching phenomena in heavy-ion collisions.

The gluon-gluon induced terms for Higgs production through weak boson fusion (WBF) are computed. Formally, these are of next-to-next-to-leading order in the strong coupling constant. This is the lowest order at which nonzero color exchange occurs between the scattering quarks, leading to a color field and thus additional hadronic activity between the outgoing jets. Using a minimal set of cuts, the numerical impact of these terms is at the percent level with respect to the next-to-leading order rate for weak boson fusion. Applying the so-called WBF cuts leads to an even stronger suppression, so that we do not expect a significant deterioration of the WBF signal by these color exchange effects.

We present the first observation and cross section measurement of exclusive dijet production in $\overline{p}p$ interactions, $\overline{p}p\to \overline{p}+\mathrm{dijet}+p$. Using a data sample of $310{\mathrm{pb}}^{-1}$ collected by the Run II Collider Detector at Fermilab at $\sqrt{s}=1.96\mathrm{TeV}$, exclusive cross sections for events with two jets of transverse energy $E_T^{\mathrm{jet}}\ge 10\mathrm{GeV}$ have been measured as a function of minimum $E_T^{\mathrm{jet}}$. The exclusive signal is extracted from fits to data distributions based on Monte Carlo simulations of expected dijet signal and background shapes. The simulated background distribution shapes are checked in a study of a largely independent data sample of $200{\mathrm{pb}}^{-1}$ of $b$-tagged jet events, where exclusive dijet production is expected to be suppressed by the $J_z=0$ total angular momentum selection rule. Results obtained are compared with theoretical expectations, and implications for exclusive Higgs boson production at the $pp$ Large Hadron Collider at $\sqrt{s}=14\mathrm{TeV}$ are discussed.

We review the Coulomb gas computation of three-point functions in the $SL(2,\mathbb{R})$ Wess-Zumino-Novikov-Witten model and obtain explicit expressions for generic states. These amplitudes have been computed in the past by this and other methods but the analytic continuation in the number of screening charges required by the Coulomb gas formalism had only been performed in particular cases. After showing that ghost contributions to the correlators can be generally expressed in terms of Schur polynomials, we solve Aomoto integrals in the complex plane, a new set of multiple integrals of Dotsenko-Fateev type. We then make use of monodromy invariance to analytically continue the number of screening operators and prove that this procedure gives results in complete agreement with the amplitudes obtained from the bootstrap approach. We also compute a four-point function involving a spectral flow operator and we verify that it leads to the one unit spectral flow three-point function according to a prescription previously proposed in the literature. In addition, we present an alternative method to obtain spectral flow nonconserving $n$-point functions through well defined operators and we prove that it reproduces the exact correlators for $n=3$. Independence of the result on the insertion points of these operators suggests that it is possible to violate winding number conservation modifying the background charge.

We study causal hydrodynamics (Israel-Stewart theory) of gauge theory plasmas from the AdS/CFT duality. Causal hydrodynamics requires new transport coefficients (relaxation times) and we compute them for a number of supersymmetric gauge theories including the $\mathcal{N}=4$ super Yang-Mills theory. However, the relaxation times obtained from the “shear mode” do not agree with the ones from the “sound mode,” which implies that the Israel-Stewart theory is not a sufficient framework to describe the gauge theory plasmas.

We investigate the intermediate and late-time behavior of the massive Dirac spinor field in the background of static spherically symmetric brane-world black hole solutions. The intermediate asymptotic behavior of the massive spinor field exhibits a dependence on the field’s parameter mass as well as the multiple number of the wave mode. On the other hand, the late-time behavior power-law decay has a rate which is independent of those factors.

In paper I of this series we discuss how magnification bias distorts the 3D correlation function by enhancing the observed correlation in the line-of-sight (LOS) orientation, especially on large scales. This lensing anisotropy is distinctive, making it possible to separately measure the galaxy-galaxy, galaxy-magnification and magnification-magnification correlations. Here we extend the discussion to the power spectrum and also to redshift space. In real space, pairs oriented close to the LOS direction are not protected against nonlinearity even if the pair separation is large; this is because nonlinear fluctuations can enter through gravitational lensing at a small transverse separation (or i.e. impact parameter). The situation in Fourier space is different: by focusing on a small wave number $k$, as is usually done, linearity is guaranteed because both the LOS and transverse wave numbers must be small. This is why magnification distortion of the galaxy correlation appears less severe in Fourier space. Nonetheless, the effect is non-negligible, especially for the transverse Fourier modes, and should be taken into account in interpreting precision measurements of the galaxy power spectrum, for instance those that focus on the baryon oscillations. The lensing induced anisotropy of the power spectrum has a shape that is distinct from the more well-known redshift space anisotropies due to peculiar motions and the Alcock-Paczynski effect. The lensing anisotropy is highly localized in Fourier space while redshift space distortions are more spread out. This means that one could separate the magnification bias component in real observations, implying that potentially it is possible to perform a gravitational lensing measurement without measuring galaxy shapes.

The constraints on the radion evolution in the universal extra dimension (UED) model from cosmic microwave background (CMB) and Type Ia supernovae (SNe Ia) data are studied. In the UED model, where both the gravity and standard model fields can propagate in the extra dimensions, the evolution of the extra-dimensional volume, the radion, induces variation of fundamental constants. We discuss the effects of variation of the relevant constants in the context of UED for the CMB power spectrum and SNe Ia data. We then use the three-year WMAP data to constrain the radion evolution at $z\sim 1100$, and the $2\sigma$ constraint on $\dot{\rho }/{\rho }_0$ ($\rho$ is a function of the radion, to be defined in the text) is $[-8.8,6.6]\times {10}^{-13}{\mathrm{yr}}^{-1}$. The SNe Ia gold sample yields a constraint on $\dot{\rho }/{\rho }_0$, for redshift between 0 and 1, to be $[-4.7,14]\times {10}^{-13}{\mathrm{yr}}^{-1}$. Furthermore, the constraints from SNe Ia can be interpreted as bounds on the evolution QCD scale parameter, ${\dot{\Lambda }}_{\mathrm{QCD}}/{\Lambda }_{\mathrm{QCD},0}$, $[-1.4,2.8]\times {10}^{-11}{\mathrm{yr}}^{-1}$, without reference to the UED model.

Charged massive particles (CHAMPs), when present during the big bang nucleosynthesis (BBN) era, may significantly alter the synthesis of light elements when compared to a standard BBN scenario. This is due to the formation of bound states with nuclei. This paper presents a detailed numerical and analytical analysis of such CHAMP BBN. All reactions important for predicting light-element yields are calculated within the Born approximation. Three previously neglected effects are treated in detail: (a) photodestruction of bound states due to electromagnetic cascades induced by the CHAMP decay, (b) late-time efficient destruction/production of ${}^2\mathrm{H}$, ${}^6\mathrm{Li}$, and ${}^7\mathrm{Li}$ due to reactions on charge $Z=1$ nuclei bound to CHAMPs, and (c) CHAMP exchange between nuclei. Each of these effects may induce orders-of-magnitude changes in the final abundance yields. The study focuses on the impact of CHAMPs on a possible simultaneous solution of the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ problems. It is shown that a previously suggested simultaneous solution of the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ problems for a relic decaying at ${\tau }_x\approx 1000\sec $ is only weakly dependent on the relic being neutral or charged, unless its hadronic branching ratio is small, $B_h\ll {10}^{-4}$. By use of a Monte Carlo analysis it is shown that within CHAMP BBN the existence of further parameter space for a simultaneous solution of the ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ problem for long decay times ${\tau }_x\gtrsim {10}^6\sec $ seems possible but fairly unlikely.

We investigate the noncommutative effect on the non-Gaussianities of primordial cosmological perturbation. In the lowest order of string length and slow-roll parameter, we find that in the models with small speed of sound the noncommutative modifications could be observable if assuming a relatively low string scale. In particular, the dominant modification of the non-Gaussianity estimator $f_{\mathrm{NL}}$ could reach $O(1)$ in Dirac-Born-Infeld (DBI) inflation and $K$-inflation. The corrections are sensitive to the speed of sound and the choice of string length scale. Moreover the shapes of the corrected non-Gaussianities are distinct from that of ordinary ones.

It has been suggested that dark matter particles are strongly interacting, composite, macroscopically large objects made of well known light quarks (or antiquarks). In doing so it is argued that these compact composite objects (CCOs) provide natural explanations of observed data, such as the 511 keV line from the bulge of our galaxy observed by INTEGRAL, and the excess of diffuse gamma rays in the 1–20 MeV band observed by COMPTEL. Here we argue that the atmospheres of positrons that surround CCOs composed of di-antiquark pairs in the favored color-flavor-locked superconducting state are sufficiently dense as to place stringent limits on the penetration depth of interstellar electrons incident upon them, resulting in an extreme suppression of previously estimated rates of positronium formation, and hence in the flux of 511 keV photons resulting from their subsequent decays. The associated rate of direct electron-positron annihilations, which yield the MeV photons postulated to explain the 1–20 MeV photon excess, is also suppressed. We also discuss how even if a fraction of positrons somehow penetrated the surface of the CCOs, the extremely strong electric fields generated from the bulk antiquark matter would result in the destruction of positronium atoms long before they decay.

We study the possibility that the current accelerated expansion of the universe is driven by the vacuum energy density of a colored scalar field which is responsible for a phase transition in which the gauge $SU(3{)}_c$ symmetry breaks. We show that if we are stuck in a $SU(3{)}_c$-preserving false vacuum, then $SU(3{)}_c$ symmetry breaking can be accommodated without violating any experimental QCD bounds or bounds from cosmological observations. Moreover, unless there is an unnatural fine-tuning beyond the usual cosmological constant fine-tuning, the true vacuum state of the universe is anti-de Sitter. The model can likely be tested at the LHC. A possible (though not necessary) consequence of the model is the existence of fractionally charged massive hadrons. The model can be embedded in supersymmetric theories where massive colored scalar fields appear naturally.

We study the degeneracies between neutrino mass and dark energy as they manifest themselves in cosmological observations. In contradiction to a popular formula in the literature, the suppression of the matter power spectrum caused by massive neutrinos is not just a function of the ratio of neutrino to total mass densities $f_{\nu }={\Omega }_{\nu }/{\Omega }_m$, but also each of the densities independently. We also present a fitting formula for the logarithmic growth factor of perturbations in a flat universe, $f(z,k;f_{\nu },w,{\Omega }_{\mathrm{DE}})\approx [1-A(k){\Omega }_{\mathrm{DE}}{f}_{\nu }+B(k)f_{\nu }^2-C(k)f_{\nu }^3]{\Omega }_m^{\alpha }(z)$, where $\alpha$ depends on the dark energy equation of state parameter $w$. We then discuss cosmological probes where the $f$ factor directly appears: peculiar velocities, redshift distortion, and the integrated Sachs-Wolfe effect. We also modify the approximation of Eisenstein and Hu [Astrophys. J. 511, 5 (1999)] for the power spectrum of fluctuations in the presence of massive neutrinos and provide a revised code [http://www.star.ucl.ac.uk/~lahav/nu_matter_power.f].

We study the equation of state strongly interacting quark matter within a Nambu-Jona-Lasinio-like model in which the chiral condensates and the color superconducting gaps are computed self-consistently as a function of the baryon density. A vector interaction term is added to the Lagrangian in order to render the quark matter equation of state stiffer. For the low density hadronic phase we use a relativistic mean field model. The phase transition to quark matter is computed by a Maxwell construction. We show that stable color-flavor-locking (CFL) cores in hybrid stars are possible if the superconducting gap is sufficiently large. Moreover we find stable stellar configurations in which two phase transitions occur, a first transition from hadronic matter to 2SC quark matter and a second transition from 2SC quark matter to CFL quark matter.

The volume dependence of the ground-state energy of $n$ identical bosons with short-range interactions in a periodic spatial volume with sides of length $L$ is calculated at order $L^{-7}$ in the large-volume expansion. This result will enable a refined determination of the ${\pi }^{+}{\pi }^{+}{\pi }^{+}$ interaction from lattice QCD calculations.

We have considered the diphoton production in the unparticle physics at the LHC. The contributions of spin-0 and spin-2 unparticles to the diphoton production are studied in the invariant mass and other kinematical distributions, along with their dependencies on the model dependent parameters. It is found that the signal corresponding to the unparticles is significant for moderate values of the couplings.

Motivated by a puzzle in the study of two-dimensional lattice quantum electrodynamics with staggered fermions, we construct a two-dimensional fermionic model with a global $U(1)$ symmetry. Our model can be mapped into a model of closed packed dimers and plaquettes. Although the model has the same symmetries as the $XY$ model, we show numerically that the model lacks the well-known Kosterlitz-Thouless phase transition. The model is always in the gapless phase showing the absence of a phase with vortex condensation. In other words the low energy physics is described by a noncompact $U(1)$ field theory. We show that by introducing an even number of layers one can introduce vortex condensation within the model and thus also induce a Kosterlitz-Thouless transition.

We propose to set the Skyrme parameters $F_{\pi }$ and $e$ such that they reproduce the physical masses of the nucleon and the deuteron. We allow deformation using an axially symmetric solution and simulated annealing to minimize the total energy for the $B=1$ nucleon and $B=2$ deuteron. First we find that axial deformations are responsible for a significant reduction (factor of $\approx 4$) of the rotational energy but also that it is not possible to get a common set of parameters $F_{\pi }$ and $e$ which would fit both nucleon and deuteron masses simultaneously at least for $m_{\pi }=138\mathrm{MeV}$, 345 MeV and 500 MeV. This suggests that either $m_{\pi }>500\mathrm{MeV}$ or additional terms must be added to the Skyrme Lagrangian.