We analyze the observed state $D_{s0}^{*}(2317{)}^{+}$ in the Bethe-Salpeter approach. Assuming that $D_{s0}^{*}(2317{)}^{+}$ is an $S$-wave $DK$ molecular bound state, we establish the Bethe-Salpeter equation for $D_{s0}^{*}(2317{)}^{+}$. With the kernel induced by $\rho$ and $\omega$ exchange diagrams, we solve the Bethe-Salpeter equation numerically and find that the bound state of $DK$ indeed can exist. We also calculate the decay width of the isospin-violating mode $D_{s0}^{*}(2317{)}^{+}\to D_s^{+}{\pi }^0$ through exchanging vector mesons $D^{*}$ and $K^{*}$ including the $\eta -{\pi }^0$ mixing effect which gives important contribution to the decay width. We find that the decay width is smaller than the resolution of the experimental detector.

We explore the LHC phenomenology of an extension of warped Higgsless models. The model is supersymmetric in the bulk and on the IR brane as introduced in [A. Knochel and T. Ohl, Phys. Rev. D 78, 045016 (2008).], corresponding to an emergence of a supersymmetric spectrum in the composite sector of the Higgsless model. In particular, the lightest neutralino is rendered stable by an $R$ parity and serves as a realistic cold dark matter candidate. The observation of missing energy signals at the LHC from the production of the lightest supersymmetric and next-to-lightest supersymmetric particle in association with third generation quarks is discussed based on simulations using WHIZARD.

We study the hidden sector effects on the mass renormalization of a simplest gauge-mediated supersymmetry breaking scenario. We point out that possible hidden sector contributions render the soft scalar masses smaller, resulting in drastically different sparticle mass spectrum at low energy. In particular, in the $\mathbf{5}+\overline{\mathbf{5}}$ minimal gauge-mediated supersymmetry breaking with high messenger scale (that is favored by the gravitino cold dark matter scenario), we show that a stau can be the next lightest superparticle for moderate values of hidden sector self-coupling. This provides a very simple theoretical model of long-lived charged next lightest superparticles, which imply distinctive signals in ongoing and upcoming collider experiments.

Some of the cleanest signals for new physics in the early runs of the LHC will involve strongly produced particles which give rise to multiple leptons by undergoing cascade decays through weakly interacting states to stable particles. Some of the most spectacular final states will involve three or more leptons, multiple jets and generally missing energy-momentum as well. A triad of the most interesting models of new physics which induce such signals is known to consist of (i) supersymmetry with $R$-parity conservation, (ii) a universal extra dimension with conservation of KK-parity, and (iii) little Higgs models with conserved $T$-parity. Similar signals could also arise if the standard model is augmented with a fourth sequential generation of heavy fermions. We study all these possibilities and show that a judiciously chosen set of observables, critically involving the number of identifiable jets and leptons, can collectively provide distinct footprints for each of these models. In fact, simple pairwise correlation of such observables can enable unambiguous identification of the underlying model, even with a relatively small data sample.

In a simple extension of the minimal supersymmetric standard model, out-of-equilibrium decays of TeV-scale exotic vectorlike squarks may generate the baryon asymmetry of the universe. Baryon number and $CP$ violation are present in the superpotential, so this mechanism does not rely on $CP$ violation in supersymmetry breaking parameters. We discuss phenomenological constraints on the model as well as potential signals for the Large Hadron Collider and electronic dipole moment experiments. A variation on the TeV-scale model allows the exotic squarks to be the messengers of gauge mediated supersymmetry breaking.

We present an $R$-parity conserving model of sneutrino dark matter within a Higgsphilic $U(1{)}^{\prime }$ extension of the minimal supersymmetric standard model. In this theory, the $\mu$ parameter and light Dirac neutrino masses are generated naturally upon the breaking of the $U(1{)}^{\prime }$ gauge symmetry. One of the right-handed sneutrinos is the lightest supersymmetric particle. The leptonic and hadronic decays of another sneutrino, taken to be the next-to-lightest superpartner, allow for a natural fit to the recent results reported by the PAMELA experiment. We perform a detailed calculation of the dark matter relic density in this scenario, and show that the model is consistent with the ATIC and Fermi LAT experiments.

We analyze the hadronization structure of both vector and axial-vector currents leading to $\tau \to KK\pi {\nu }_{\tau }$ decays. At leading order in the $1/N_C$ expansion, and considering only the contribution of the lightest resonances, we work out, within the framework of the resonance chiral Lagrangian, the structure of the local vertices involved in those processes. The couplings in the resonance theory are constrained by imposing the asymptotic behavior of vector and axial-vector spectral functions ruled by QCD. In this way we predict the hadron spectra and conclude that, contrary to previous assertions, the vector contribution dominates by far over the axial-vector one in all $KK\pi$ charge channels.

In-medium chiral symmetry breaking in confining potential models of QCD is examined. Past attempts to analyze these models have been hampered by infrared divergences that appear at nonzero temperature. We argue that previous attempts to circumvent this problem are not satisfactory and demonstrate a simple resolution. We also show that the expectation that confining models do not exhibit a chiral phase transition is incorrect. The effect of summing ring diagrams is investigated, and we present the first determination of the temperature-density phase diagram for three model systems. We find that observables and the phase structure of the confinement models depend strongly on whether vacuum polarization is accounted for. Finally, it appears that standard confinement models cannot adequately describe both hadron phenomenology and in-medium properties of QCD.

We reconstruct $B^{\pm }\to D{K}^{\pm }$ decays in a data sample collected by the CDF II detector at the Tevatron collider corresponding to $1{\mathrm{fb}}^{-1}$ of integrated luminosity. We select decay modes where the $D$ meson decays to either $K^{-}{\pi }^{+}$ (flavor eigenstate) or $K^{-}{K}^{+}$, ${\pi }^{-}{\pi }^{+}$ ($CP$-even eigenstates), and measure the direct $CP$ asymmetry $A_{CP+}=0.39\pm 0.17(\mathrm{stat})\pm 0.04(\mathrm{syst})$, and the double ratio of $CP$-even to flavor eigenstate branching fractions $R_{CP+}=1.30\pm 0.24(\mathrm{stat})\pm 0.12(\mathrm{syst})$. These measurements will improve the determination of the Cabibbo-Kobayashi-Maskawa angle $\gamma$. They are performed here for the first time using data from hadron collisions.

In this paper we formulate $\mathcal{N}=1$ supergravity as a constrained $BF$ theory with $OSp(4|1)$ gauge superalgebra. We derive the modified supergravity Lagrangian that, apart from standard supergravity with a negative cosmological constant, contains terms proportional to the (inverse of the) Immirzi parameter. Although these terms do not change classical field equations, they might be relevant in quantum theory. We briefly discuss the perturbation theory around the supersymmetric topological vacuum.

We discuss the correspondence between degenerate fields of the ${\mathcal{W}}_N$ algebra and punctures of Gaiotto’s description of the Seiberg-Witten curve of $\mathcal{N}=2$ superconformal gauge theories. Namely, we find that the type of degenerate fields of the ${\mathcal{W}}_N$ algebra, with null states at level one, is classified by Young diagrams with $N$ boxes, and that the singular behavior of the Seiberg-Witten curve near the puncture agrees with that of ${\mathcal{W}}_N$ generators. We also find how to translate mass parameters of the gauge theory to the momenta of the Toda theory.

The nonleptonic weak processes $s+u\to u+d$ and $u+d\to s+u$ are known to dominate the dissipation mechanism responsible for the viscosity of strange quark matter in its normal phase. The rates of such processes remain unknown for many color superconducting phases of quark matter. In this paper, we partially fill up the gap by calculating the difference of the rates of the two nonleptonic weak processes in four transverse spin-one color superconducting phases of quark matter (slightly) out of $\beta$ equilibrium. The four phases studied are the color-spin locked phase, the polar phase, the planar phase, and the $A$ phase. In the limit of vanishing color superconducting gap, we reproduce the known results in the normal phase. In the general case, the rates are suppressed relative to the normal phase. The degree of the suppression is determined by the structure of the gap function in momentum space, which in turn is determined by the pairing pattern of quarks. At low temperatures, the rate is dominated by the ungapped modes. In this limit, the strongest suppression of the rate occurs in the color-spin-locked phase, and the weakest is in the polar phase and the $A$ phase.

The lower bound of the shear viscosity to entropy density ratio is examined using an exact representation of the ratio through the density of states. Under certain assumptions it can be shown that the lower bound of the ratio is not universal; its value is determined by the entropy density. Some examples of physical systems are discussed in the paper where one can expect violation of the conformal $1/4\pi$ value.

We study the full entanglement dynamics of two uniformly accelerated Unruh-DeWitt detectors with no direct interaction in between but each coupled to a common quantum field and moving back-to-back in the field vacuum. For two detectors initially prepared in a separable state our exact results show that quantum entanglement between the detectors can be created by the quantum field under some specific circumstances, though each detector never enters the other’s light cone in this setup. In the weak coupling limit, this entanglement creation can occur only if the initial moment is placed early enough and the proper acceleration of the detectors is not too large or too small compared to the natural frequency of the detectors. Once entanglement is created it lasts only a finite duration, and always disappears at late times. Prior result by Reznik [B. Reznik, Found. Phys. 33, 167 (2003).] derived using the time-dependent perturbation theory with extended integration domain is shown to be a limiting case of our exact solutions at some specific moment. In the strong coupling and high acceleration regime, vacuum fluctuations experienced by each detector locally always dominate over the cross correlations between the detectors, so entanglement between the detectors will never be generated.

We show that $CPT$-even aetherlike Lorentz-breaking actions, for the scalar and electromagnetic fields, are generated via their appropriate Lorentz-breaking coupling to spinor fields, in three, four, and five space-time dimensions. Besides, we also show that aetherlike terms for the spinor field can be generated as a consequence of the same couplings. We discuss the dispersion relations in the theories with aetherlike Lorentz-breaking terms and find the tree-level effective (Breit) potential for fermion scattering and the one-loop effective potential corresponding to the action of the scalar field.

Passerini and Severini have recently shown that the Braunstein-Ghosh-Severini (BGS) entropy $S_{\Gamma }=-\mathrm{Tr}[{\rho }_{\Gamma }\log {\rho }_{\Gamma }]$ of a certain density matrix ${\rho }_{\Gamma }$ naturally associated to a graph $\Gamma$, is maximized, among all graphs with a fixed number of links and nodes, by regular graphs. We ask if this result can play a role in quantum gravity, and be related to the apparent regularity of the physical geometry of space. We show that in loop quantum gravity the matrix ${\rho }_{\Gamma }$ is precisely the Hamiltonian operator (suitably normalized) of a nonrelativistic quantum particle interacting with the quantum gravitational field, if we restrict elementary area and volume eigenvalues to a fixed value. This operator provides a spectral characterization of the physical geometry, and can be interpreted as a state describing the spectral information about the geometry available when geometry is measured by its physical interaction with matter. It is then tempting to interpret its BGS entropy $S_{\Gamma }$ as a genuine physical entropy: we discuss the appeal and the difficulties of this interpretation.

We study the Fock description of a quantum free field on the three-sphere with a mass that depends explicitly on time, also interpretable as an explicitly time dependent quadratic potential. We show that, under quite mild restrictions on the time dependence of the mass, the specific Fock representation of the canonical commutation relations which is naturally associated with a massless free field provides a unitary dynamics even when the time varying mass is present. Moreover, we demonstrate that this Fock representation is the only acceptable one, up to unitary equivalence, if the vacuum has to be $SO(4)$-invariant (i.e., invariant under the symmetries of the field equation) and the dynamics is required to be unitary. In particular, the analysis and uniqueness of the quantization can be applied to the treatment of cosmological perturbations around Friedmann-Robertson-Walker spacetimes with the spatial topology of the three-sphere, like e.g. for gravitational waves (tensor perturbations). In addition, we analyze the extension of our results to free fields with a time dependent mass defined on other compact spatial manifolds. We prove the uniqueness of the Fock representation in the case of a two-sphere as well, and discuss the case of a three-torus.

We study the formation of a black hole and its subsequent evaporation in a model employing a minisuperspace approach to loop quantum gravity. In previous work the static solution was obtained and shown to be singularity-free. Here, we examine the more realistic dynamical case by generalizing the static case with the help of the Vaidya metric. We track the formation and evolution of trapped surfaces during collapse and evaporation and examine the buildup of quantum gravitationally caused stress energy preventing the formation of a singularity.

In models of natural inflation, the inflaton is an axionlike particle. Unfortunately, axion potentials in UV-complete theories appear to be too steep to drive inflation. We show that, even for a steep potential, natural inflation can occur if the coupling between axion and gauge fields is taken into account. Because of this coupling, quanta of the gauge field are produced by the rolling of the axion. If the coupling is large enough, such a dissipative effect slows down the axion, leading to inflation even for a steep potential. The spectrum of perturbations is quasiscale invariant, but in the simplest construction its amplitude is larger than ${10}^{-5}$. We discuss a possible way out of this problem.

We report on the analysis of the low-energy electron-recoil spectrum from the CDMS II experiment using data with an exposure of 443.2 kg-days. The analysis provides details on the observed counting rate and possible background sources in the energy range of 2–8.5 keV. We find no significant excess of a peaked contribution to the total counting rate above the background model, and compare this observation to the recent DAMA results. In the framework of a conversion of a dark matter particle into electromagnetic energy, our 90% confidence level upper limit of $0.246\mathrm{\text{events}}/\mathrm{kg}/\mathrm{day}$ at 3.15 keV is lower than the total rate above background observed by DAMA. In absence of any specific particle physics model to provide the scaling in cross section between NaI and Ge, we assume a $Z^2$ scaling. With this assumption the observed rate in DAMA remains higher than the upper limit in CDMS. Under the conservative assumption that the modulation amplitude is 6% of the total rate we obtain upper limits on the modulation amplitude a factor of $\sim 2$ lower than observed by DAMA, constraining some possible interpretations of this modulation.