We present results from a detailed numerical study of the small-scale and loop production properties of cosmic string networks, based on the largest and highest resolution string simulations to date. We investigate the nontrivial fractal properties of cosmic strings, in particular, the fractal dimension and renormalized string mass per unit length, and we also study velocity correlations. We demonstrate important differences between string networks in flat (Minkowski) spacetime and the two very similar expanding cases. For high resolution matter era network simulations, we provide strong evidence that small-scale structure has converged to “scaling” on all dynamical length scales, without the need for other radiative damping mechanisms. We also discuss preliminary evidence that the dominant loop production size is also approaching scaling.

This paper investigates the parameter space of theories with gauge-mediated supersymmetry breaking leading to gravitino (cold) dark matter with mass $m_{3/2}\sim 1\mathrm{keV}\to 10\mathrm{MeV}$. We pay particular attention to the cosmological role of messenger fields. Cosmology requires that these messengers decay to the visible sector if the lightest messenger mass $M_X\gtrsim 30\mathrm{TeV}$. We then examine the various possible messenger number violating interactions allowed by the symmetries of the theory and by phenomenology. Late messenger decay generally results in entropy production hence in the dilution of preexisting gravitinos. We find that in $SU(5)$ grand unification only specific messenger-matter couplings allow to produce the required amount of gravitino dark matter particles. Gravitino dark matter with the correct abundance is, however, expected in larger gauge groups such as $SO(10)$ for generic nonrenormalizable messenger-matter interactions and for arbitrarily high post-inflationary reheating temperatures.

We study possible restoration patterns of chiral symmetry in a generalized hidden local symmetry model, which is a low-energy effective theory of QCD including pseudoscalar, vector and axial-vector mesons. We derive Wilsonian renormalization-group equations and analyze the running couplings and their fixed points at the chiral restoration point. We find three types of the chiral restoration, which are classified as the standard, vector manifestation and intermediate scenarios, respectively. It turns out that the rho and $A_1$ meson become massless and their decay into pion is suppressed in all the restoration patterns. Each restoration scenario violates or fulfills the vector-meson dominance at the critical point in a different manner, which may reflect on the contributions from the pion to the dilepton spectrum.

We study inclusive semileptonic $\overline{B}\to X_c\ell {\overline{\nu }}_{\ell }$ decay using the power counting $m_c\sim \sqrt{{\Lambda }_{\mathrm{QCD}}{m}_b}$. Assuming this scaling for the charm-quark mass, the decay kinematics can be chosen to access the shape-function region even in $b\to c$ transitions. To apply effective field theory methods in this region we extend soft-collinear effective theory to describe massive collinear quarks. We calculate the tree-level decay rate, including $\mathcal{O}({\Lambda }_{\mathrm{QCD}}/m_b)$ power corrections, and show that it factorizes into a convolution of jet and shape functions. We identify a certain kinematical variable whose decay spectrum is proportional to the universal leading-order shape function familiar from $b\to u$ decay, and speculate as to whether information about this shape function can be extracted from data on $b\to c$ decay.

Due to the presence of quantum correlations in the $C=-1$ and $C=+1$ $D^0{\overline{D}}^0$ pairs produced in the reactions $e^{+}{e}^{-}\to D^0{\overline{D}}^0(n{\pi }^0)$ and $e^{+}{e}^{-}\to D^0{\overline{D}}^0\gamma (n{\pi }^0)$, respectively, the time-integrated $D^0{\overline{D}}^0$ decay rates are sensitive to interference between amplitudes for indistinguishable final states. The size of this interference is governed by the relevant amplitude ratios and can include contributions from $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing. We present a method for simultaneously measuring the magnitudes and phases of these amplitude ratios and searching for $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing. We make use of fully- and partially-reconstructed $D^0{\overline{D}}^0$ pairs in both $C$ eigenstates, and we estimate experimental sensitivities based on a plausible charm factory data set. Similar analyses can be applied to coherent $K^0{\overline{K}}^0$, $B^0{\overline{B}}^0$, or $B_s^0{\overline{B}}_s^0$ pairs.

We have reanalyzed the world data on inclusive polarized DIS, in both NLO and LO QCD, including the new HERMES and COMPASS data. The updated NLO polarized densities are given in both the $\overline{\mathrm{MS}}$ and JET schemes. The impact of the new data on the results is discussed.

We consider the effective topological field theory on Euclidean D-strings wrapping on a 2-cycle in the internal space. We evaluate the vacuum expectation value of a suitable operator corresponding to the chemical potential of vortices bounded to the D-strings, and find that it reduces to the partition function of generalized two-dimensional Yang-Mills theory as a result of localization. We argue that the partition function gives a grand canonical ensemble of multi-instanton corrections for four-dimensional $\mathcal{N}=2$ gauge theory in a suitable large $N$ limit. We find two-dimensional gauge theories that provide the instanton partition function for four-dimensional $\mathcal{N}=2$ theories with the hypermultiplets in the adjoint and fundamental representations. We also propose a partition function that gives the instanton contributions to four-dimensional $\mathcal{N}=2$ quiver gauge theory. We discuss the relation between Nekrasov’s instanton partition function and the Dijkgraaf-Vafa theory in terms of large $N$ phase transitions of the generalized two-dimensional Yang-Mills theory.

We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming CMB experiments such as BICEP, QUaD, BRAIN, ClOVER and Planck to the nonzero total neutrino mass $M_{\nu }$ indicated by current neutrino oscillation data. We find that these experiments greatly benefit from lensing extraction techniques, improving their one-sigma sensitivity to $M_{\nu }$ by a factor of order four. The combination of data from Planck and the SAMPAN mini-satellite project would lead to $\sigma (M_{\nu })\sim 0.1$ eV, while a value as small as $\sigma (M_{\nu })\sim 0.035$ eV is within the reach of a space mission based on bolometers with a passively cooled 3–4 m aperture telescope, representative of the most ambitious projects currently under investigation. We show that our results are robust not only considering possible difficulties in subtracting astrophysical foregrounds from the primary CMB signal but also when the minimal cosmological model ($\Lambda$ Mixed Dark Matter) is generalized in order to include a possible scalar tilt running, a constant equation-of-state parameter for the dark energy and/or extra relativistic degrees of freedom.

In this article we elaborate on a recently proposed interpretation of deformed special relativity (DSR) as an effective measurement theory in the presence of non-negligible (albeit small) quantum gravitational fluctuations. We provide several heuristic arguments to explain how such a new theory can emerge and discuss the possible observational consequences of this framework. Given that our discussion considers leading order corrections to the standard dispersion relations, our results apply to a very wide class of possible modifications of special relativity.

We study gravitational lensing by compact objects in gravity theories that can be written in a post-post-Newtonian (PPN) framework: i.e., the metric is static and spherically symmetric, and can be written as a Taylor series in ${\mathsf{m}}_{•}/r$, where ${\mathsf{m}}_{•}$ is the gravitational radius of the compact object. Working invariantly, we compute corrections to standard weak-deflection lensing observables at first and second order in the perturbation parameter $\epsilon ={\vartheta }_{•}/{\vartheta }_E$, where ${\vartheta }_{•}$ is the angular gravitational radius and ${\vartheta }_E$ is the angular Einstein ring radius of the lens. We show that the first-order corrections to the total magnification and centroid position vanish universally for gravity theories that can be written in the PPN framework. This arises from some surprising, fundamental relations among the lensing observables in PPN gravity models. We derive these relations for the image positions, magnifications, and time delays. A deep consequence is that any violation of the universal relations would signal the need for a gravity model outside the PPN framework (provided that some basic assumptions hold). In practical terms, the relations will guide observational programs to test general relativity, modified gravity theories, and possibly the cosmic censorship conjecture. We use the new relations to identify lensing observables that are accessible to current or near-future technology, and to find combinations of observables that are most useful for probing the spacetime metric. We give explicit applications to the galactic black hole, microlensing, and the binary pulsar J0737-3039.

In this work a new set of boundary conditions for Chern-Simons gravity that lead to a fully gauge invariant action is analyzed. This particular form of the action reproduces the standard results of black hole thermodynamics and determines that the algebra of charges of diffeomorphisms at the horizon is the Virasoro algebra.

We study a recently proposed mechanism to solve the hierarchy problem in the context of the landscape, where the solution of the hierarchy problem is connected to the requirement of having baryons in our Universe via electroweak baryogenesis. The phase transition is triggered by the fermion condensation of a new gauge sector which becomes strong at a scale $\Lambda$ determined by dimensional transmutation, and it is mediated to the standard model by a new singlet field. In a “friendly” neighborhood of the landscape, where only the relevant operators are “scanned” among the vacua, baryogenesis is effective only if the Higgs mass $m_h$ is comparable to this low scale $\Lambda$, forcing $m_h\sim \Lambda$, and solving the hierarchy problem. A new $CP$ violating phase is needed coupling the new singlet and the Higgs field to new matter fields. We study the constraints on this model given by baryogenesis and by the electron electric dipole moment (EDM), and we briefly comment on gauge coupling unification and on dark matter relic abundance. We find that next generation experiments on the EDM will be sensitive to essentially the entire viable region of the parameter space, so that absence of a signal would effectively rule out the model.

We consider a singlino-dominated neutralino in supersymmetric models with an extra U(1). In case both the $\mu$ term and also the $Z^{\prime }$ mass are generated by the vacuum expectation value of the scalar component of the same singlet chiral superfield, generically the lightest neutralino is not expected to be dominated by the singlino. However, if the gaugino corresponding to the extra U(1) is sufficiently heavy, the lightest neutralino can be dominated by the singlino and still satisfy the constraints resulting from the $Z^{\prime }$ phenomenology. We assume a supersymmetry breaking scenario in which the extra U(1) gaugino can be much heavier than other gauginos. In that framework we show that the singlino-dominated lightest neutralino may be a good candidate for dark matter in a parameter space where various phenomenological constraints are satisfied.

We make a comprehensive study of the theory and phenomenology of a low-energy supersymmetric standard model originating from a string-inspired $E_6$ grand unified gauge group. The exceptional supersymmetric standard model (ESSM) considered here is based on the low-energy standard model gauge group together with an extra $Z^{\prime }$ corresponding to an extra $U(1{)}_N$ gauge symmetry under which right-handed neutrinos have zero charge. The low-energy matter content of the ESSM corresponds to three 27 representations of the $E_6$ symmetry group, to ensure anomaly cancellation, plus an additional pair of Higgs-like doublets as required for high-energy gauge coupling unification. The ESSM is therefore a low-energy alternative to the minimal supersymmetric standard model (MSSM) or next-to-minimal supersymmetric standard model (NMSSM). The ESSM involves extra matter beyond the MSSM contained in three $5+5^{*}$ representations of $SU(5)$, plus three $SU(5)$ singlets which carry $U(1{)}_N$ charges, one of which develops a vacuum expectation value, providing the effective $\mu$ term for the Higgs doublets, as well as the necessary exotic fermion masses. We explore the renormalization group flow of the ESSM and examine theoretical restrictions on the values of new Yukawa couplings caused by the validity of perturbation theory up to the grand unification scale. We then discuss electroweak symmetry breaking and Higgs phenomenology and establish an upper limit on the mass of the lightest Higgs particle which can be significantly heavier than in the MSSM and NMSSM, in leading two-loop approximation. We also discuss the phenomenology of the $Z^{\prime }$ and the extra matter, whose discovery will provide a smoking gun signal of the model.

We compute the energy of the ground state and a low-lying excitation of the gluonic field in the presence of static quark-anti-quark ($q\overline{q}$) sources. We show that for separation between the sources less then a few fm the gluonic ground state of the static $q\overline{q}$ system can be well described in terms of a mean field wave functional with the excited states corresponding to a single quasiparticle excitation of the gluon field. We also discuss the role of many particle excitations relevant for large separation between sources.

In this article we consider the three-particle decays ${\chi }_{b0,2}\to J/\psi c\overline{c}\to J/\psi D\overline{D}+X$. We present the analytical formulas for the differential widths of these decays, the numerical values of their integrated widths, and check the duality relation that connects the decays ${\chi }_{b0,2}\to \psi c\overline{c}$ with the two-particle decays ${\chi }_{b0,2}\to J/\psi (c\overline{c})$. We also study the possibility of observing the ${\chi }_{b0,2}\to J/\psi D\overline{D}+X$ mode at Tevatron and LHC colliders.

We study KKLT type models with moduli-mixing superpotential. In several string models, gauge kinetic functions are written as linear combinations of two or more moduli fields. Their gluino condensation generates moduli-mixing superpotential. We assume one of moduli fields is frozen already around the string scale. It is found that Kähler modulus can be stabilized at a realistic value without tuning 3-form fluxes because of gluino condensation on (non-)magnetized D-brane. Furthermore, we do not need to highly tune parameters in order to realize a weak gauge coupling and a large hierarchy between the gravitino mass and the Planck scale, when there exists nonperturbative effects on D3-brane. SUSY breaking patterns in our models have a rich structure. Also, some of our models have cosmologically important implications, e.g., on the overshooting problem and the destabilization problem due to finite temperature effects as well as the gravitino problem and the moduli problem.

We assume that weak bases of flavors $(u,c{)}_{L,R}$, $(d,s{)}_{L,R}$, $(e,\mu {)}_{L,R}$, $({\nu }_e,{\nu }_{\mu }{)}_{L,R}$ are the $S_3$ doublet and $t_{L,R}$, $b_{L,R}$, ${\tau }_{L,R}$, ${\nu }_{\tau L,R}$ are the $S_3$ singlet and further there are $S_3$ doublet Higgs ($H_D^1$, $H_D^2$) and $S_3$ singlet Higgs $H_S$. We suggest a $S_3$ invariant Yukawa interaction, in which masses caused from the interaction of $S_3$ singlet flavors and Higgs are very large and masses caused from interactions of $S_3$ doublet flavors and Higgs are very small, and the vacuum expectation value $⟨|H_D^1|{⟩}_0$ is rather small compared to the $⟨|H_D^2|{⟩}_0$. In this model, we can explain the quark sector mass hierarchy, flavor mixing $V_{\mathrm{CKM}}$, and measure of $CP$ violation naturally. The leptonic sector mass hierarchy and flavor mixing described by $V_{\mathrm{MNS}}$ having one maximal and one large mixing character can also be explained naturally with no other symmetry restriction. In our model, an origin of Cabibbo angle is the ratio $\lambda =⟨|H_D^1|{⟩}_0/⟨|H_D^2|{⟩}_0$ and an origin of $CP$ violation is the phase of $H_D^1$.

In the present work, we quantize three Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and radiation. The models differ from each other by the constant curvature of their spatial sections, which may be positive, negative or zero. They give rise to Wheeler-DeWitt equations for the scale factor which have the form of the Schrödinger equation for the quartic anharmonic oscillator. We find their eigenvalues and eigenfunctions by using a method first developed by Chhajlany and Malnev. After that, we use the eigenfunctions in order to construct wave packets for each case and evaluate the time-dependent expectation value of the scale factors, which are found to oscillate between finite maximum and minimum values. Since the expectation values of the scale factors never vanish, we have an initial indication that these models may not have singularities at the quantum level.

Except for the presence of gravitational wave source term, the relativistic perturbation equations of a zero-pressure irrotational fluid in a flat Friedmann world model coincide exactly with the Newtonian ones to the second order in perturbations. Such a relativistic-Newtonian correspondence is available in a special gauge condition (the comoving gauge) in which all the variables are equivalently gauge invariant. In this work we compare our results with the ones in the synchronous gauge which has been used often in the literature. Although the final equations look simpler in the synchronous gauge, the variables have remnant gauge modes. Except for the presence of the gauge mode for the perturbed-order variables, however, the equations in the synchronous gauge are gauge invariant and can be exactly identified as the Newtonian hydrodynamic equations in the Lagrangian frame. In this regard, the relativistic equations to the second order in the comoving gauge are the same as the Newtonian hydrodynamic equations in the Eulerian frame. We resolve several issues related to the two gauge conditions often to fully nonlinear orders in perturbations.