In this paper, in a class of warped compactifications with the brane/flux annihilation, we find that the inflation may be driven by a flat direction identified as that along the number $p$ of $\overline{\mathrm{D}3}$ branes located at the tip of the Klebanov-Strassler throat. The spectrum of adiabatic perturbation generated during inflation is nearly scale invariant, which may be obtained by using the results shown in the phantom inflation, since in a four-dimension effective description the evolution of energy density along the $p$ direction is slowly increasing.

If inflation is to be considered in an unbiased way, as possibly originating from one of a wide range of underlying theories, then observations need not be simply applied to reconstructing the inflaton potential $V(\varphi )$ or a specific kinetic term, as in Dirac-Born-Infeld inflation, but rather to reconstruct the inflationary action in its entirety. We discuss the constraints that can be placed on a general single field action from measurements of the primordial scalar and tensor fluctuation power spectra and non-Gaussianities. The analytic form of the action that is consistent with data turns out to be surprisingly simple and easy to categorize. We also present the flow equation formalism for reconstructing a general inflationary Lagrangian $\mathcal{L}(X,\varphi )$, with $X=\frac{1}{2}{\partial }_{\mu }\varphi {\partial }^{\mu }\varphi$, in a general gauge, that reduces to canonical and DBI inflation in the specific gauge ${\mathcal{L}}_X=c_s^{-1}$.

We present a phase-space noncommutative extension of quantum cosmology and study the Kantowski-Sachs cosmological model requiring that the two scale factors of the Kantowski-Sachs metric, the coordinates of the system, and their conjugate canonical momenta do not commute. Through the Arnowitt-Deser-Misner formalism, we obtain the Wheeler-DeWitt (WDW) equation for the noncommutative system. The Seiberg-Witten map is used to transform the noncommutative equation into a commutative one, i.e. into an equation with commutative variables, which depend on the noncommutative parameters $\theta$ and $\eta$. Numerical solutions are found both for the classical and the quantum formulations of the system. These solutions are used to characterize the dynamics and the state of the universe. From the classical solutions we obtain the behavior of quantities such as the volume expansion, the shear, and the characteristic volume. However, the analysis of these quantities does not lead to any restriction on the value of the noncommutative parameters $\theta$ and $\eta$. On the other hand, for the quantum system, one can obtain, via the numerical solution of the WDW equation, the wave function of the universe for commutative as well as for the noncommutative models. Interestingly, we find that the existence of suitable solutions of the WDW equation imposes bounds on the values of the noncommutative parameters. Moreover, the noncommutativity in the momenta leads to damping of the wave function, implying that this noncommutativity can be of relevance for the selection of possible initial states of the early universe.

The Gaussian effective potential is derived for the non-Abelian $\mathrm{SU}(2)\times \mathrm{U}(1)$ gauge theory of electroweak interactions. At variance with naive derivations, the Gaussian effective potential is proven to be a genuine variational tool in any gauge. The role of ghosts is discussed and the unitarity gauge is shown to be the only choice which allows calculability without insertion of further approximations. The full non-Abelian calculation confirms the existence of a light Higgs boson in the nonperturbative strong coupling regime of the Higgs sector.

Discovery potentials for extra neutral interactions at the Large Hadron Collider in forthcoming experiments are analyzed using resonant leptoproduction. For this purpose we use high precision next-to-next-to-leading order determinations of the QCD background in this channel, at the tail of the Drell-Yan distributions, in the invariant mass region around $0.8<Q<2.5\mathrm{TeV}$. We focus our analysis primarily on a novel string-inspired $Z^{\prime }$, obtained in left-right symmetric free fermionic heterotic string models and whose existence at low energies is motivated by its role in suppressing proton decay mediation. We analyze the parametric dependence of the predictions and perform comparison with other models based on bottom-up approaches, that are constructed by requiring anomaly cancellation and enlarged Higgs structure. We show that the results are not particularly sensitive to the specific charge assignments. This may render quite difficult the extraction of significant information from the forward-backward asymmetries on the resonance, assuming that these are possible due to a sizeable width. The challenge to discover extra (nonanomalous) $Z^{\prime }$ in this kinematic region remains strongly dependent on the size of the new gauge coupling. Weakly coupled extra $Z^{\prime }$ will not be easy to identify even with a very good theoretical determination of the QCD background through next-to-next-to-leading order.

We discuss ILC measurements for a specific MSSM scenario with $CP$ phases, where the lightest neutralino is a good candidate for dark matter, annihilating efficiently through t-channel exchange of light staus. These prospective ($CP$-even) ILC measurements are then used to fit the underlying model parameters. A collider prediction of the relic density of the neutralino from this fit gives $0.116<\Omega h^2<0.19$ at 95% C.L. $CP$-odd observables, while being a direct signal of $CP$ violation, do not help in further constraining $\Omega h^2$. The interplay with (in)direct detection of dark matter and with measurements of electric dipole moments is also discussed. Finally we comment on collider measurements at higher energies for refining the prediction of $\Omega h^2$.

We have calculated the neutron electric dipole moment (EDM) in the presence of the $CP$ violating $\theta$ term in lattice QCD with two-flavor dynamical clover quarks, using the external electric field method. Accumulating a large number of statistics by the averages over 16 different source points and over forward and backward nucleon propagators, we have obtained nonzero signals of neutron and proton EDM beyond 1 standard deviation at each quark mass in full QCD. We have investigated the quark mass dependence of nucleon EDM in full QCD, and have found that nucleon EDM in full QCD does not decrease toward the chiral limit, as opposed to the theoretical expectation. We briefly discuss possible reasons for this behavior.

We study screening correlators of quark-antiquark composites at $T=2T_c$, where $T_c$ is the QCD phase transition temperature, using overlap quarks in the quenched approximation of lattice QCD. As the lattice spacing is changed from $1/4T$ to $a=1/6T$ and $1/8T$, we find that screening correlators change little, in contrast with the situation for other types of lattice fermions. All correlators are close to the ideal gas prediction at small separations. The long distance falloff is clearly exponential, showing that a parametrization by a single screening length is possible at distances $z\ge 1/T$. The correlator corresponding to the thermal vector is close to the ideal gas value at all distances, whereas that for the thermal scalar deviates at large distances. This is examined through the screening lengths and momentum space correlators. There is strong evidence that the screening transfer matrix does not have reflection positivity.

Based on recent work on nuclear binding, we update and extend the anthropic constraints on the light quark masses, with results that are more tightly constrained than previously obtained. We find that heavy nuclei would fall apart (because the attractive nuclear central potential becomes too weak) if the sum of the light quark masses $m_u+m_d$ would exceed their physical values by 64% (at 95% confidence level). We summarize the anthropic constraints that follow from requiring the existence both of heavy atoms and of hydrogen. With the additional assumption that the quark Yukawa couplings do not vary, these constraints provide a remarkably tight anthropic window for the Higgs vacuum expectation value: $0.39<v/v_{\mathrm{physical}}<1.64$.

Certain time-dependent configurations in the $c=1$ matrix model correspond to string theory backgrounds which have spacelike boundaries and appear geodesically incomplete. We investigate quantum mechanical properties of a class of such configurations in the matrix model, in terms of fermionic eigenvalues. We describe Hamiltonian evolution of the eigenvalue density using several different time variables, some of which are infinite and some of which are finite in extent. We derive unitary transformations relating these different descriptions, and use those to calculate fermion correlators in the time-dependent background. Using the chiral formalism, we write the time-dependent configurations as a state in the original matrix model Hilbert space.

Generically, the classical evolution of the inflaton has a brief fast-roll stage that precedes the slow-roll regime. The fast-roll stage leads to a purely attractive potential in the wave equations of curvature and tensor perturbations (while the potential is purely repulsive in the slow-roll stage). This attractive potential leads to a depression of the CMB quadrupole moment for the curvature and $B$-mode angular power spectra. A single new parameter emerges in this way in the early universe model: the comoving wave number $k_1$ characteristic scale of this attractive potential. This mode $k_1$ happens to exit the horizon precisely at the transition from the fast-roll to the slow-roll stage. The fast-roll stage dynamically modifies the initial power spectrum by a transfer function $D(k)$. We compute $D(k)$ by solving the inflaton evolution equations. $D(k)$ effectively suppresses the primordial power for $k<k_1$ and possesses the scaling property $D(k)=\Psi (k/k_1)$ where $\Psi (x)$ is a universal function. We perform a Monte Carlo Markov chain analysis of the WMAP and SDSS data including the fast-roll stage and find the value $k_1=0.266{\mathrm{Gpc}}^{-1}$. The quadrupole mode $k_Q=0.242{\mathrm{Gpc}}^{-1}$ exits the horizon earlier than $k_1$, about one-tenth of an $e$-fold before the end of fast roll. We compare the fast-roll fit with a fit without fast roll but including a sharp lower cutoff on the primordial power. Fast roll provides a slightly better fit than a sharp cutoff for the temperature–temperature, temperature–$E$ modes, and $E$ modes–$E$ modes. Moreover, our fits provide nonzero lower bounds for $r$, while the values of the other cosmological parameters are essentially those of the pure $\Lambda \mathrm{CDM}$ model. We display the real space two point $C^{\mathrm{TT}}(\theta )$ correlator. The fact that $k_Q$ exits the horizon before the slow-roll stage implies an upper bound in the total number of $e$-folds $N_{\mathrm{tot}}$ during inflation. Combining this with estimates during the radiation dominated era we obtain $N_{\mathrm{tot}}\sim 66$, with the bounds $62<N_{\mathrm{tot}}<82$. We repeated the same analysis with the WMAP-5, ACBAR-2007, and SDSS data confirming the overall picture.

As an addendum to our previous evaluation of the weak-interaction corrections to hadronic top-quark pair production [W. Bernreuther, M. Fücker, and Z. G. Si, Phys. Rev. D 74, 113005 (2006).], we determine the leading weak-interaction contributions due to the subprocesses $b\overline{b}\to t\overline{t}$ and $gq(\overline{q})\to t\overline{t}q(\overline{q})$. For several distributions in $t\overline{t}$ production at the CERN LHC, we find that these contributions are non-negligible as compared to the weak corrections from the other partonic subprocesses.

We have searched for bound states in the $\pi \Lambda N$ system by solving the nonrelativistic Faddeev equations, as well as a relativistic version, with input separable $\pi N$, $\pi \Lambda$, and $\Lambda N$ interactions. A bound-state solution, driven by the $\Delta (1232)$ and the $\Sigma (1385)$ $p$-wave meson-baryon resonances, was found in the channel $(I,J^P)=(\frac{3}{2},2^{+})$, provided the $\Lambda$ laboratory momentum at which the $\Lambda N$ ${}^{3}S_1$ phase shift becomes negative is larger than $p_{\mathrm{lab}}\sim 750–800\mathrm{MeV}/\mathrm{c}$. Other strange and charmed $\pi B{B}^{\prime }$ systems that might have bound states of a similar nature are listed.

Using $230\times {10}^6$ $B\overline{B}$ events recorded with the BABAR detector at the $e^{+}{e}^{-}$ storage rings PEP-II, we reconstruct approximately 4100 $B^0\to J/\psi K^{+}{\pi }^{-}$ and 9930 $B^{+}\to J/\psi K^{+}$ decays with $J/\psi \to {\mu }^{+}{\mu }^{-}$ and $e^{+}{e}^{-}$. From the measured $B$-momentum distributions in the $e^{+}{e}^{-}$ rest frame, we determine the mass difference $m(B^0)-m(B^{+})=(+0.33\pm 0.05\pm 0.03)\mathrm{MeV}/c^2$.

We present a solution of the five-dimensional gravity-dilaton-tachyon equations of motion with a pure ${\mathrm{AdS}}_5$ metric and a quadratic dilaton and linear tachyon in conformal coordinates. This leads to an infrared soft-wall model where the dilaton profile gives rise to linear Regge trajectories for the four-dimensional mass spectrum of the dual gauge theory. Even though our approach is phenomenological the scalar fields resemble the dilaton and the closed string tachyon of a noncritical string theory. Interestingly, the linear tachyon has the correct profile to imply that chiral symmetry is not restored for highly excited states. Our solution thus provides a dynamical bottom-up model of linear confinement in holographic QCD.

The class of static, spherically symmetric, and finite energy hedgehog solutions in the SU(2) Skyrme model is examined on a metric three-cylinder. The exact analytic shape function of the 1-Skyrmion is found. It can be expressed via elliptic integrals. Its energy is calculated, and its stability with respect to radial and spherically symmetric deformations is analyzed. No other topologically nontrivial solutions belonging to this class are possible on the three-cylinder.

Local gauge symmetries cannot break spontaneously, according to Elitzur’s theorem, but this leaves open the possibility of breaking some global subgroup of the local gauge symmetry, which is typically the gauge symmetry remaining after certain (e.g. Coulomb or Landau) gauge choices. We show that in an SU(2) gauge-Higgs system such symmetries do indeed break spontaneously, but the location of the breaking in the phase diagram depends on the choice of global subgroup. The implication is that there is no unique broken gauge symmetry, but rather many symmetries which break in different places. The problem is to decide which, if any, of these gauge-symmetry breakings is associated with a transition between physically different, confining and nonconfining phases. Several proposals—Kugo-Ojima, Coulomb, and monopole condensate—are discussed.

We use a functional approach to calculate the Casimir energy due to Dirac fields in interaction with thin, flat, parallel walls, which implement imperfect baglike boundary conditions. These are simulated by the introduction of $\delta$-like interactions with the walls. We show that, with a proper choice for the corresponding coupling constants, bag-model boundary conditions are properly implemented. We obtain explicit expressions for the energies in $1+1$ and $3+1$ dimensions, for massless and massive fields.

An analytical solution of Einstein-Maxwell equations with a static fluid as a source is presented. The spacetime is represented by the axially symmetric Weyl metric and the energy-momentum tensor describes a coupling of a fluid with an electromagnetic field. When appropriate limits are performed we recover the well-known solutions of Gutsunaev-Manko and Schwarzschild. Also, using Eckart’s thermodynamics, we calculated the temperature, the mechanical pressure, the charge density, and the energy density of the system. The analysis of thermodynamic quantities suggests that the solution can be used to represent a magnetized compact stellar object surrounded by a charged fluid.

Recollapsing homogeneous and isotropic models present one of the key ingredients for cyclic scenarios. This is considered here within a quantum cosmological framework in the presence of a free scalar field with, in turn, a negative cosmological constant and spatial curvature. Effective equations shed light on the quantum dynamics around a recollapsing phase and the evolution of state parameters such as fluctuations and correlations through such a turn around. In the models considered here, the squeezing of an initial state is found to be strictly monotonic in time during the expansion, turn around, and contraction phases. The presence of such monotonicity is of potential importance in relation to a long-standing debate concerning the (a)symmetry between the expanding and contracting phases in a recollapsing universe. Furthermore, together with recent analogous results concerning a bounce, one can extend this monotonicity throughout an entire cycle. This provides a strong motivation for employing the degree of squeezing as an alternative measure of (quantum) entropy. It may also serve as a new concept of emergent time described by a variable without classical analog. The evolution of the squeezing in emergent oscillating scenarios can in principle provide constraints on the viability of such models.