Two-time (2T) gravity in $d+2$ dimensions predicts 1T general relativity in $d$ dimensions, augmented with a local scale symmetry known as the Weyl symmetry in 1T field theory. The emerging general relativity comes with a number of constraints, particularly on scalar fields and their interactions in 1T field theory. These constraints, detailed in this paper, are footprints of 2T gravity and could be a basis for testing 2T physics. Some of the conceptually interesting consequences of the “accidental” Weyl symmetry include that the gravitational constant emerges from vacuum values of the dilaton and other Higgs-type scalars and that it changes after every cosmic phase transition (inflation, grand unification, electroweak phase transition, etc.). We show that this consequential Weyl symmetry in $d$ dimensions originates from coordinate reparametrization, not from scale transformations, in the $d+2$ spacetime of 2T gravity. To recognize this structure we develop in detail the geometrical structures, curvatures, symmetries, etc. of the $d+2$ spacetime which is restricted by a homothety condition derived from the action of 2T gravity. Observers that live in $d$ dimensions perceive general relativity and all degrees of freedom as shadows of their counterparts in $d+2$ dimensions. Kaluza-Klein type modes are removed by gauge symmetries and constraints that follow from the 2T-gravity action. However some analogs to Kaluza-Klein modes, which we call “prolongations” of the shadows into the higher dimensions, remain but they are completely determined, up to gauge freedom, by the shadows in $d$ dimensions.

We consider the entanglement dynamics between two Unruh-DeWitt detectors at rest separated at a distance $d$. This simple model when analyzed properly in quantum field theory shows many interesting facets and helps to dispel some misunderstandings of entanglement dynamics. We find that there is spatial dependence of quantum entanglement in the stable regime due to the phase difference of vacuum fluctuations the two detectors experience, together with the interference of the mutual influences from the backreaction of one detector on the other. When two initially entangled detectors are still outside each other’s light cone, the entanglement oscillates in time with an amplitude dependent on spatial separation $d$. When the two detectors begin to have causal contact, an interference pattern of the relative degree of entanglement (compared to those at spatial infinity) develops a parametric dependence on $d$. The detectors separated at those $d$ with a stronger relative degree of entanglement enjoy longer disentanglement times. In the cases with weak coupling and large separation, the detectors always disentangle at late times. For sufficiently small $d$, the two detectors can have residual entanglement even if they initially were in a separable state, while for $d$ a little larger, there could be transient entanglement created by mutual influences. However, we see no evidence of entanglement creation outside the light cone for initially separable states.

Using gauge-invariant perturbation theory, we study the effects of stellar magnetic fields on polar gravitational waves emitted during the collapse of homogeneous dust. We found that the emitted energy in gravitational waves depends strongly on the initial stellar radius as well as on the ratio between the poloidal and toroidal magnetic components. The polar gravitational-wave output of such a collapse can easily be up to a few orders of magnitude larger than what we get from the nonmagnetized collapse. The changes due to the existence of a magnetic field could be helpful in extracting some information about inner magnetic profiles of progenitors from the detection of the gravitational waves radiated during black hole formation, which results from the stellar collapse.

In recent work by two of us, [Durrer & Ruser, Phys. Rev. Lett. 99, 071601 (2007); Ruser & Durrer Phys. Rev. D 76, 104014 (2007)], graviton production due to a moving spacetime boundary (braneworld) in a five dimensional bulk has been considered. In the same way as the presence of a conducting plate modifies the electromagnetic vacuum, the presence of a brane modifies the graviton vacuum. As the brane moves, the time dependence of the resulting boundary condition leads to particle creation via the so-called ’dynamical Casimir effect’. In our previous work a term in the boundary condition which is linear in the brane velocity has been neglected. In this work we develop a new approach which overcomes this approximation. We show that the previous results are not modified if the brane velocity is low.

Chemical-potential dependence of pi and sigma meson masses is analyzed at both real and imaginary chemical potentials, ${\mu }_{\mathrm{R}}$ and ${\mu }_{\mathrm{I}}$, by using the Polyakov-loop extended Nambu–Jona-Lasinio (PNJL) model that possesses both the extended ${\mathbb{Z}}_3$ symmetry and chiral symmetry. In the ${\mu }_{\mathrm{I}}$ region, the meson masses have the Roberge-Weiss periodicity. The ${\mu }_{\mathrm{I}}$ dependence of the meson masses becomes stronger as temperature increases. We argue that meson masses and physical quantities in the ${\mu }_{\mathrm{R}}$ region will be determined from lattice QCD data on meson masses in the ${\mu }_{\mathrm{I}}$ region by using the PNJL model, if the data are measured in the future.

Supersymmetric models with broken $R$ parity provide mechanisms that allow to generate Majorana neutrino masses and magnetic moments through virtual particle-sparticle loops. This constitutes an attractive alternative to the seesaw mechanism. In this paper, we present a detailed calculation of the transition magnetic moments of a Majorana neutrino in gauge-mediated supersymmetry breaking minimal supersymmetric standard model (MSSM) without $R$ parity. We base our analysis on the renormalization group evolution of the MSSM parameters, which are unified at the grand unified theory scale.

We propose a new realization of softly broken supersymmetric theories as theories defined on stochastic superspace. At the classical level, the supersymmetry breaking is parametrized in terms of a single (in general complex) mass parameter, $\xi$, describing the stochasticity of the Grassmannian superspace coordinates. In the context of the standard model with stochastic supersymmetry, the structure of the soft-breaking terms has various characteristic features that can be tested in LHC experiments. Namely, at the classical level, the $B_{\mu }$ parameter, the universal soft trilinear coupling $A_0$, the universal gaugino mass $m_{1/2}$, and the universal scalar mass $m_0$ are given solely in terms of $\xi$; there are no other arbitrary parameters. The relations are $B_{\mu }={\xi }^{*}$, $A_0=2{\xi }^{*}$, $m_{1/2}=|\xi |/2$, and $m_0=0$. At the quantum level, these relations hold at a certain scale $\Lambda$ which is a second free parameter. The soft scalar masses, zero at tree level, are induced radiatively through the renormalization group equations at one loop. With this pattern of soft-breaking terms, large supersymmetric contributions to flavor changing neutral current processes are avoided. As a concrete illustration of the proposed formalism, we consider a minimal model, which is just the constrained minimal supersymmetric standard model with the stochastic superspace relations among the soft-breaking parameters imposed at the scale $\Lambda$. We show that this theory is phenomenologically viable for a certain region in the $(\xi ,\Lambda )$ parameter space. Some sensible extensions of the minimal model are then briefly discussed.

Utilizing recent deep inelastic scattering measurements $({\sigma }_r,F_{2,3,L})$ and data on hadronic dilepton production we determine at next-to-next-to-leading order (NNLO) (3-loop) of QCD the dynamical parton distributions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale ($Q_0^2<1{\mathrm{GeV}}^2$). These are compared with “standard” NNLO distributions generated from positive input distributions at some fixed and higher resolution scale ($Q_0^2>1{\mathrm{GeV}}^2$). Although the NNLO corrections imply in both approaches an improved value of ${\chi }^2$, typically ${\chi }_{\mathrm{NNLO}}^2\simeq 0.9{\chi }_{\mathrm{NLO}}^2$, present deep inelastic scattering data are still not sufficiently accurate to distinguish between NLO results and the minute NNLO effects of a few percent, despite the fact that the dynamical NNLO uncertainties are somewhat smaller than the NLO ones and both are, as expected, smaller than those of their standard counterparts. The dynamical predictions for $F_L(x,Q^2)$ become perturbatively stable already at $Q^2=2–3{\mathrm{GeV}}^2$ where precision measurements could even delineate NNLO effects in the very small-$x$ region. This is in contrast to the common standard approach but NNLO/NLO differences are here less distinguishable due to the larger $1\sigma$ uncertainty bands. Within the dynamical approach we obtain ${\alpha }_s(M_Z^2)=0.1124\pm 0.0020$, whereas the somewhat less constrained standard fit gives ${\alpha }_s(M_Z^2)=0.1158\pm 0.0035$.

The availability of branching fractions for a large majority of $D_s$ decays permits the prediction of inclusive branching fractions. This is achieved with the help of a modest amount of input from an isospin statistical model applied to nonresonant multibody $D_s$ decays. A systematic uncertainty in these mostly small branching ratios is estimated by comparing predictions of this model with those of a model involving quark-antiquark pair production. The calculated inclusive branching fractions can be compared with data (for example, from a large sample of $D_s^{+}{D}_s^{*-}+D_s^{*+}{D}_s^{-}$ obtained by the CLEO Collaboration) and examined for specific final states which can shed light on strong and weak decay mechanisms.

Isolated horizon conditions enforce the time invariance of both the intrinsic and the extrinsic geometry of a (quasilocal) black hole horizon. Nonexpanding horizons, only requiring the invariance of the intrinsic geometry, have been successfully employed in the (excision) initial data of black holes in instantaneous equilibrium. Here we propose the use of the full isolated horizon structure when solving the elliptic system resulting from the complete set of conformal $3+1$ Einstein equations under a quasiequilibrium ansatz prescription. We argue that a set of geometric inner boundary conditions for this extended elliptic system then follows, determining the shape of the excision surface.

Fermionic condensate and the vacuum expectation values of the energy-momentum tensor are investigated for a massive spinor field in higher-dimensional spacetimes with an arbitrary number of toroidally compactified spatial dimensions. By using the Abel-Plana summation formula and the zeta function technique we present the vacuum expectation values in two different forms. Applications of the general formulas to cylindrical and toroidal carbon nanotubes are given. We show that the topological Casimir energy is positive for metallic cylindrical nanotubes and is negative for semiconducting ones. The toroidal compactification of a cylindrical nanotube along its axis increases the Casimir energy for metallic-type (periodic) boundary conditions along its axis and decreases the Casimir energy for the semiconducting-type compactifications.

It is shown that the $E_{6(6)}$ symmetric entropy formula describing black holes and black strings in $D=5$ is intimately tied to the geometry of the generalized quadrangle GQ(2, 4) with automorphism group the Weyl group $W(E_6)$. The 27 charges correspond to the points and the 45 terms in the entropy formula to the lines of GQ(2, 4). Different truncations with 15, 11 and 9 charges are represented by three distinguished subconfigurations of GQ(2, 4), well known to finite geometers; these are the “doily” [i.e. GQ(2, 2)] with 15, the “perp set” of a point with 11, and the “grid” [i.e. GQ(2, 1)] with nine points, respectively. In order to obtain the correct signs for the terms in the entropy formula, we use a noncommutative labeling for the points of GQ(2, 4). For the 40 different possible truncations with nine charges this labeling yields 120 Mermin squares—objects well known from studies concerning Bell-Kochen-Specker-like theorems. These results are connected to our previous ones obtained for the $E_{7(7)}$ symmetric entropy formula in $D=4$ by observing that the structure of GQ(2, 4) is linked to a particular kind of geometric hyperplane of the split Cayley hexagon of order 2, featuring 27 points located on nine pairwise disjoint lines (a distance-3-spread). We conjecture that the different possibilities of describing the $D=5$ entropy formula using Jordan algebras, qubits and/or qutrits correspond to employing different coordinates for an underlying noncommutative geometric structure based on GQ(2, 4).

The basic characteristics of the covariant chiral current $⟨J_{\mu }⟩$ and the covariant chiral energy-momentum tensor $⟨T_{\mu \nu }⟩$ are obtained from a chiral effective action. These results are used to justify the covariant boundary condition used in recent approaches of computing the Hawking flux from chiral gauge and gravitational anomalies. We also discuss a connection of our results with the conventional calculation of nonchiral currents and stress tensors in different (Unruh, Hartle-Hawking and Boulware) states.

We describe a simple model of dark matter, which explains the PAMELA/ATIC excesses while being consistent with all present constraints. The DAMA annual modulation signal can also be explained for some values of the parameters. The model consists of a dark sector containing a weakly coupled broken $U(1)$ gauge symmetry, under which only the dark matter state and the leptons are charged.

Using tachyon or quintessence fields along with a barotropic fluid on the brane we examine the different cosmological stages in a Friedmann-Robertson-Walker universe, from the first radiation scenario to the later era dominated by cosmic string networks. We introduce a new algorithm to generalize previous works on exact solutions and apply it to study tachyon and quintessence fields localized on the brane. We also explore the low and high energy regimes of the solutions. Besides, we show that the tachyon and quintessence fields are driven by an inverse power law potential. Finally, we find several simple exacts solutions for tachyon and/or quintessence fields.

Most of the mass content of dark matter haloes is expected to be in the form of tidal debris. The density of debris is not constant, but rather can grow due to formation of caustics at the apocenters and pericenters of the orbit, or decay as a result of phase mixing. In the phase space, the debris assemble in a hierarchy that is truncated by the primordial temperature of dark matter. Understanding this phase structure can be of significant importance for the interpretation of many astrophysical observations and, in particular, dark matter detection experiments. With this purpose in mind, we develop a general theoretical framework to describe the hierarchical structure of the phase space of cold dark matter haloes. We do not make any assumption of spherical symmetry and/or smooth and continuous accretion. Instead, working with correlation functions in the action-angle space, we can fully account for the hierarchical structure (predicting a two-point correlation function $\propto \Delta J^{-1.6}$ in the action space), as well as the primordial discreteness of the phase space. As an application, we estimate the boost to the dark matter annihilation signal due to the structure of the phase space within virial radius: the boost due to the hierarchical tidal debris is of order unity, whereas the primordial discreteness of the phase structure can boost the total annihilation signal by up to an order of magnitude. The latter is dominated by the regions beyond 20% of the virial radius, and is largest for the recently formed haloes with the least degree of phase mixing. Nevertheless, as we argue in a companion paper, the boost due to small gravitationally-bound substructure can dominate this effect at low redshifts.

The effects of SU(3) symmetry breaking and configuration mixing have been investigated for the weak vector and axial-vector form factors in the chiral constituent quark model ($\chi \mathrm{CQM}$) for the strangeness changing as well as strangeness conserving semileptonic octet baryon decays in the nonperturbative regime. The results are in good agreement with existing experimental data and also show improvement over other phenomenological models.

We investigate on exotic tetraquark hadrons of the kind $[cs][\overline{c}\overline{s}]$ by computing their spectrum and decay modes within a constituent diquark-antidiquark model. We also compare these predictions with the present experimental knowledge.

We show that the $R$-parity violating decays of the lighter top squarks (${\tilde{t}}_1$) triggered by the lepton number violating couplings ${\lambda }_{i33}^{\prime }$, where the lepton family index $i=1–3$, can be observed at the LHC via the dilepton dijet channel even if the coupling is as small as ${10}^{-4}$ or ${10}^{-5}$. This is the case in several models of neutrino mass, provided the ${\tilde{t}}_1$ is the next lightest supersymmetric particle and the lightest neutralino is the lightest supersymmetric particle. First, we have obtained a fairly model-independent estimate of the minimum observable value of the parameter [$P_{ij}\equiv \mathrm{BR}(\tilde{t}\to l_i^{+}b)\times \mathrm{BR}({\tilde{t}}^{*}\to l_j^{-}\overline{b})$] at the LHC for an integrated luminosity of $10{\mathrm{fb}}^{-1}$ as a function of $m_{{\tilde{t}}_1}$ by a standard Pythia based analysis. We have then computed the parameter $P_{ij}$ in several representative models of neutrino mass constrained by the neutrino oscillation data and have found that the theoretical predictions are above the estimated minimum observable levels for a wide region of the parameter space.

Low-energy supersymmetry (SUSY) and several other theories that address the hierarchy problem predict pair-production at the LHC of particles with standard model quantum numbers that decay to jets, missing energy, and possibly leptons. If an excess of such events is seen in LHC data, a theoretical framework in which to describe it will be essential to constraining the structure of the new physics. We propose a basis of four deliberately simplified models, each specified by only 2–3 masses and 4–5 branching ratios, for use in a first characterization of data. Fits of these simplified models to the data furnish a quantitative presentation of the jet structure, electroweak decays, and heavy-flavor content of the data, independent of detector effects. These fits, together with plots comparing their predictions to distributions in data, can be used as targets for describing the data within any full theoretical model.