We find that for a large enough strange quark mass, $m_s^2/4\mu \Delta >2/3(1-0.023)$ ($\mu$ is the quark number chemical potential, $\Delta$ is the superconducting gap), the kaon condensed color flavor locked (CFL) phase of asymptotically dense strongly interacting 3 flavor quark matter is unstable with respect to spontaneous generation of currents of Nambu Goldstone bosons due to spontaneous breaking of baryon number symmetry and hypercharge symmetry in the $\mathrm{CFL}{K}^0$ ground state. The total baryon and hypercharge currents vanish in the ground state. We find that $\mathrm{CFL}{K}^0$ and the new state are separated by a first order phase transition. The result is derived in the mean field approximation of high density effective theory with electromagnetic interactions turned off.

We study the rare decays $B_u^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-}$, ${\rho }^{+}{\ell }^{+}{\ell }^{-}$ and $B_d^0\to {\ell }^{+}{\ell }^{-}$ ($\ell =e$, $\mu$) in the $R$-parity violating supersymmetric standard model. From the latest upper limits of $\mathcal{B}(B_u^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-})$ and $\mathcal{B}(B_d^0\to {\ell }^{+}{\ell }^{-})$, we have derived new upper bounds on the relevant $R$-parity violating couplings products, which are stronger than the existing ones. Using the constrained parameter space, we present the $R$-parity violating effects on the branching ratios and the forward-backward asymmetries of these decays. We find that $\mathcal{B}(B_d^0\to {\ell }^{+}{\ell }^{-})$ and $\mathcal{B}(B_u^{+}\to {\rho }^{+}{\ell }^{+}{\ell }^{-})$ could be enhanced several orders by the $R$-parity violating sneutrino and squark exchanges, respectively. The $R$-parity violating effects on the dilepton invariant mass spectra of $B_u^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-}$, ${\rho }^{+}{\ell }^{+}{\ell }^{-}$ and the normalized forward-backward asymmetry ${\mathcal{A}}_{\mathrm{FB}}(B_u^{+}\to {\pi }^{+}{\ell }^{+}{\ell }^{-})$ and ${\mathcal{A}}_{\mathrm{FB}}(B_u^{+}\to {\rho }^{+}{\ell }^{+}{\ell }^{-})$ are studied in detail. Our results could be used to probe the $R$-parity violating effects and will correlate with searches for the direct $R$-parity violating signals at the future experiments.

The forward-backward asymmetry ${\mathcal{A}}_{\mathrm{FB}}$ in $B\to K^{*}{\ell }^{+}{\ell }^{-}$ decay is a sensitive probe of new physics. Previous studies have focused on the sensitivity in the position of the zero. However, the effective Wilson coefficients (short distance effective couplings) are in principle complex, as illustrated by $B\to \rho {\ell }^{+}{\ell }^{-}$ decay within the standard model. Allowing for this, but keeping the $B\to K^{*}\gamma$ and $K^{*}{\ell }^{+}{\ell }^{-}$ rate constraints, we find the landscape for ${\mathcal{A}}_{\mathrm{FB}}(B\to K^{*}{\ell }^{+}{\ell }^{-})$ to be far richer than from entertaining just sign flips. The complex nature of effective Wilson coefficients can be explored by future high statistics experiments.

We present a study of excited charm-strange baryon states produced in $e^{+}{e}^{-}$ annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of $384{\mathrm{fb}}^{-1}$ recorded with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ storage rings at the Stanford Linear Accelerator Center. We study strong decays of charm-strange baryons to ${\Lambda }_c^{+}{K}_S^0$, ${\Lambda }_c^{+}{K}^{-}$, ${\Lambda }_c^{+}{K}^{-}{\pi }^{+}$, ${\Lambda }_c^{+}{K}_S^0{\pi }^{-}$, ${\Lambda }_c^{+}{K}_S^0{\pi }^{-}{\pi }^{+}$, and ${\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$. This study confirms the existence of the states ${\Xi }_c(2980{)}^{+}$, ${\Xi }_c(3077{)}^{+}$, and ${\Xi }_c(3077{)}^0$, with a more accurate determination of the ${\Xi }_c(2980{)}^{+}$ mass and width. We also present evidence for two new states, ${\Xi }_c(3055{)}^{+}$ and ${\Xi }_c(3123{)}^{+}$, decaying through the intermediate-resonant modes ${\Sigma }_c(2455{)}^{++}{K}^{-}$ and ${\Sigma }_c(2520{)}^{++}{K}^{-}$, respectively. For each of these baryons, we measure the yield in each final state, determine the statistical significance, and calculate the product of the production cross section and branching fractions. We also measure the masses and widths of these excited charm-strange baryons.

We calculate in a very simple way the spectrum of giant magnon bound states at strong coupling in $\mathcal{N}=4$ super Yang-Mills theory (SYM), by utilizing the description of the field theory vacuum in terms of a condensate of eigenvalues of commuting matrices. We further show that these calculations can be understood in terms of the central charge extension that permits the calculation of Bogomol’nyi-Prasad-Sommerfield masses in the Coulomb branch of $\mathcal{N}=4$ SYM. This paper shows further evidence that the strong coupling expansion of the maximally supersymmetric Yang-Mills theory in four dimensions can be done systematically from first principles, without the assumption of integrability.

Preliminary results concerning the time evolution of strongly exited $SU(2)$ Bogomolny-Prasad-Sommerfield (BPS) magnetic monopoles have been published in G. Fodor and I. Rácz, Phys. Rev. Lett. 92, 151801 (2004). The behavior of these dynamical magnetic monopoles was investigated by means of numerical simulations in the four-dimensional Minkowski spacetime. The developed code—although applied to spherically symmetric configurations—incorporates both the techniques of conformal compactification and that of the hyperboloidal initial value problem. Our primary aim here is to provide a detailed account on the methods and results of the investigations reported in G. Fodor and I. Rácz, Phys. Rev. Lett. 92, 151801 (2004). In addition, some important new results, which go much beyond the scope of these early studies, are also presented. In particular, to be able to distinguish linear and nonlinear effects, evolutions of monopoles deformed by various excitations, including both very small and extra large energy excitation, are investigated. In addition, a detailed account is provided on the spacetime dependence of the basic variables, as well as that of the other physically significant dynamical qualities such as the energy and energy current densities, the radial and angular pressures, and the magnetic charge density. A careful comprehensive study of the associated energy transfers and energy balances is also included.

Evidence has recently emerged for a hidden symmetry of planar scattering amplitudes in $\mathcal{N}=4$ super-Yang-Mills theory called dual conformal symmetry. At weak coupling the presence of this symmetry has been observed through five loops, while at strong coupling the symmetry has been shown to have a natural interpretation in terms of a $T$-dualized ${\mathrm{AdS}}_5$. In this paper we study dual conformally invariant off-shell four-point Feynman diagrams. We classify all such diagrams through four loops and evaluate 10 new off-shell integrals in terms of Mellin-Barnes representations, also finding explicit expressions for their infrared singularities.

We propose a $(3+1)\mathrm{D}$ linear set of covariant vector equations, which unify the spin-0 “new Dirac equation” with its spin-$1/2$ counterpart, proposed by Staunton. Our equations describe a spin-$(0,1/2)$ supermultiplet with different numbers of degrees of freedom in the bosonic and fermionic sectors. The translation-invariant spin degrees of freedom are carried by two copies of the Heisenberg algebra. This allows us to realize space-time supersymmetry in a bosonized form. The grading structure is provided by an internal reflection operator. Then the construction is generalized by means of the Majorana equation to a supersymmetric theory of massive higher-spin particles. The resulting theory is characterized by a nonlinear symmetry superalgebra, that, in the large-spin limit, reduces to the super-Poincaré algebra with or without tensorial central charge.

We give a rigorous and mathematically clear presentation of the covariant and gauge-invariant theory of gravitational waves in a perturbed Friedmann-Lemaître-Robertson-Walker universe for fourth order gravity, where the matter is described by a perfect fluid with a barotropic equation of state. As an example of a consistent analysis of tensor perturbations in fourth order gravity, we apply the formalism to a simple background solution of $R^n$ gravity. We obtain the exact solutions of the perturbation equations for scales much bigger than and smaller than the Hubble radius. It is shown that the evolution of tensor modes is highly sensitive to the choice of $n$ and an interesting new feature arises. During the radiation dominated era, their exists a growing tensor perturbation for nearly all choices of $n$. This occurs even when the background model is undergoing accelerated expansion as opposed to the case of general relativity. Consequently, cosmological gravitational wave modes can in principle provide a strong constraint on the theory of gravity independent of other cosmological data sets.

We consider cosmology in the Einstein-Æther theory (the generally covariant theory of gravitation coupled to a dynamical timelike Lorentz-violating vector field) with a linear Æ-Lagrangian. The $3+1$ spacetime splitting approach is used to derive covariant and gauge invariant perturbation equations which are valid for a general class of Lagrangians. Restricting attention to the parameter space of these theories which is consistent with local gravity experiments, we show that there are tracking behaviors for the Æ field, both in the background cosmology and at the linear perturbation level. The primordial power spectrum of scalar perturbations in this model is shown to be the same as that predicted by standard general relativity. However, the power spectrum of tensor perturbation is different from that in general relativity, but has a smaller amplitude and so cannot be detected at present. We also study the implications for late-time cosmology and find that the evolution of photon and neutrino anisotropic stresses can source the Æ field perturbation during the radiation and matter dominated epochs, and as a result the CMB and matter power spectra are modified. However, these effects are degenerate with respect to other cosmological parameters, such as neutrino masses and the bias parameter in the observed galaxy spectrum.

We study the Hawking radiation in the framework of open quantum systems by examining the time evolution of a detector (modeled by a two-level atom) interacting with vacuum massless scalar fields. The dynamics of the detector is governed by a master equation obtained by tracing over the field degrees of freedom from the complete system. The nonunitary effects are studied by analyzing the time behavior of a particular observable of the detector, i.e., its admissible state, in the Unruh, Hartle-Hawking, as well as Boulware vacua outside a Schwarzschild black hole. We find that the detector in both the Unruh and Hartle-Hawking vacua would spontaneously excite with a nonvanishing probability the same as what one would obtain if there is thermal radiation at the Hawking temperature from the black hole, thus reproducing the basic results concerning the Hawking effect in the framework of open quantum systems.

Rolling tachyon backgrounds, arising from open strings on unstable branes in bosonic string theory, can be related to a simple statistical mechanical model-Coulomb gas of point charges in two dimensions confined to a circle, the Dyson gas. In this paper we describe a statistical system that is dual to non-BPS branes in superstring theory. We argue that even though the concept of time is absent in the statistical dual sitting at equilibrium, the notion of time can emerge at the large number of particles $N\to \infty$ limit.

We have studied preheating of field perturbations in a 3-dimensional lattice including the effect of scalar metric perturbations in two generic models of inflation: chaotic inflation with a quartic potential and standard hybrid inflation. We have prepared the initial state for the classical evolution of the system with vanishing vector and tensor metric perturbations, consistent with the constraint equations, the energy and momentum constraints. The nonlinear evolution inevitably generates vector and tensor modes, and this reflects on how well the constraint equations are fulfilled during the evolution. The induced preheating of the scalar metric perturbations is not large enough to backreact onto the fields, but it could affect the evolution of vector and tensor modes. This is the case in hybrid inflation for some values of the coupling $g$ and the height of potential $V_0^{1/4}$. For example with $V_0^{1/4}\simeq {10}^{15}\mathrm{GeV}$, preheating of scalar perturbations is such that their source term in the evolution equation for tensor and vector fluctuations becomes comparable to that of the field anisotropic stress.

The presence of inhomogeneities modifies the cosmic distances through the gravitational lensing effect, and, indirectly, must affect the main cosmological tests. Assuming that the dark energy is a smooth component, the simplest way to account for the influence of clustering is to suppose that the average evolution of the expanding Universe is governed by the total matter-energy density whereas the focusing of light is only affected by a fraction of the total matter density quantified by the $\alpha$ Dyer-Roeder parameter. By using two different samples of SNe type Ia data, the ${\Omega }_m$ and $\alpha$ parameters are constrained by applying the Zeldovich-Kantowski-Dyer-Roeder luminosity distance-redshift relation for a flat ($\Lambda \mathrm{CDM}$) model. A ${\chi }^2$-analysis using the 115 SNe Ia data of the Astier et al. sample (2006) constrains the density parameter to be ${\Omega }_m={0.26}_{-0.07}^{+0.17}$ ($2\sigma$) while the $\alpha$ parameter is weakly limited (all the values $\in [0,1]$ are allowed even at $1\sigma$). However, a similar analysis based the 182 SNe Ia data of Riess et al. (2007) constrains the pair of parameters to be ${\Omega }_m={0.33}_{-0.07}^{+0.09}$ and $\alpha \ge 0.42$ ($2\sigma$). Basically, this occurs because the Riess et al. sample extends to appreciably higher redshifts. As a general result, even considering the existence of inhomogeneities as described by the smoothness $\alpha$ parameter, the Einstein-de Sitter model is ruled out by the two samples with a high degree of statistical confidence ($11.5\sigma$ and $9.9\sigma$, respectively). The inhomogeneous Hubble-Sandage diagram discussed here highlights the necessity of the dark energy, and a transition deceleration/accelerating phase at $z\sim 0.5$ is also required.

The process $gg\to h_0\to \gamma \gamma$ is studied in the Lee-Wick extension of the standard model (LWSM) proposed by Grinstein, O’Connell, and Wise. In this model, negative norm partners for each SM field are introduced with the aim to cancel quadratic divergences in the Higgs mass. All sectors of the model relevant to $gg\to h_0\to \gamma \gamma$ are diagonalized and results are commented on from the perspective of both the Lee-Wick and higher-derivative formalisms. Deviations from the SM rate for $gg\to h_0$ are found to be of the order of 15%–5% for Lee-Wick masses in the range 500–1000 GeV. Effects on the rate for $h_0\to \gamma \gamma$ are smaller, of the order of 5%–1% for Lee-Wick masses in the same range. These comparatively small changes may well provide a means of distinguishing the LWSM from other models such as universal extra dimensions where same-spin partners to standard model fields also appear. Corrections to determinations of Cabibbo-Kobayashi-Maskawa (CKM) elements $|V_{t(b,s,d)}|$ are also considered and are shown to be positive, allowing the possibility of measuring a CKM element larger than unity, a characteristic signature of the ghostlike nature of the Lee-Wick fields.

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass $m/T=0.4$ and find that a first order phase transition line appears in the high density regime for ${\mu }_q/T\gtrsim 2.5$. We also discuss the difference between the phase structures of QCD with nonzero quark chemical potential and nonzero isospin chemical potential.

The fat-link irrelevant clover fermion action is a variant of the $O(a)$-improved Wilson action where the irrelevant operators are constructed using smeared links. While the use of such smearing allows for the use of highly improved definitions of the field strength tensor $F_{\mu \nu }$, we show that the standard 1-loop clover term with a mean field improved coefficient $c_{\mathrm{sw}}$ is sufficient to remove the $O(a)$ errors, avoiding the need for nonperturbative tuning. This result enables efficient dynamical simulations in QCD with the fat-link irrelevant clover fermion action

We calculate the electroweak and QCD corrections to $W^{-}{W}^{+}\to t\overline{t}$ and $ZZ\to t\overline{t}$. We also consider the interplay of these corrections with the effect of anomalous interactions that affect the massive weak bosons and the top. The results at the $VV$ level fusion are convoluted with the help of the effective vector boson approximation to give predictions for a high energy $e^{+}{e}^{-}$ collider.