We discuss short-baseline electron and muon neutrino disappearance searches into sterile neutrinos at a very low energy neutrino factory (VLENF) with a muon energy between about 2 and 4 GeV. A lesson learned from reactor experiments, such as Double Chooz and Daya Bay, is to use near and far detectors with identical technologies to reduce the systematical errors (the VLENF has been recently renamed into nuSTORM-Neutrinos from STORed Muons). We therefore derive the physics results from a combined near-far detector fit and illustrate that uncertainties on $\mathrm{\text{cross sections}}\times \mathrm{\text{efficiencies}}$ can be eliminated in a self-consistent way. We also include the geometry of the setup, i.e., the extension of the decay straight and the muon decay kinematics relevant at the near detector, and we demonstrate that these affect the sensitivities for $\Delta m^2\gtrsim 30{\mathrm{eV}}^2$, where oscillations take place already in the near detector. Compared to appearance searches, we find that the sensitivity depends on the locations of both detectors and the muon energy, where the near detector should be as close as possible to the source, and the far detector at about 500 to 800 m. In order to exclude the currently preferred parameter region, at least ${10}^{19}$ useful muon decays per polarity are needed for $E_{\mu }=2\mathrm{GeV}$, or, alternatively, a higher muon energy can be used.

It is known that the covariant graviton two-point function in de Sitter spacetime is infrared-divergent for some choices of gauge parameters. On the other hand, it is also known that there are no infrared divergences requiring an infrared cutoff for the physical graviton two-point function for this spacetime in the transverse-traceless-synchronous gauge in the global coordinate system. We show in this paper that the covariant graviton Wightman two-point function with two gauge parameters is equivalent to the physical one in the global coordinate system in the sense that they produce the same two-point function of any local gauge-invariant tensor linear in the graviton field such as the linearized Weyl tensor. This confirms the fact, pointed out decades ago, that the infrared divergences of the graviton two-point function in the covariant gauge for some choices of gauge parameters are a gauge artifact in the sense that they do not contribute to the Wightman two-point function of any local gauge-invariant tensor field in linearized theory.

If supersymmetry is discovered at the LHC, the next question will be the determination of the underlying model. While this may be challenging or even intractable, a more optimistic question is whether we can understand the main contours of any particular paradigm of the mediation of supersymmetry breaking. The determination of superpartner masses through endpoint measurements of kinematic observables arising from cascade decays is a powerful diagnostic tool. In particular, the determination of the gaugino sector has the potential to discriminate between certain mediation schemes (not all schemes, and not between different UV realizations of a given scheme). We reconstruct gaugino masses, choosing a model where anomaly contributions to supersymmetry breaking are important (KKLT compactification), and find the gaugino unification scale. Moreover, reconstruction of other superpartner masses allows us to solve for the parameters defining the UV model. The analysis is performed in the stop and stau coannihilation regions where the lightest neutralinos are mainly gauginos, to additionally satisfy dark matter constraints. We thus develop observables to determine stau and stop masses to verify that the coannihilation mechanism is indeed operational, and solve for the relic density.

We apply the conformal gravity theory to a sample of 111 spiral galaxies whose rotation curve data points extend well beyond the optical disk. With no free parameters other than galactic mass-to-light ratios, the theory is able to account for the systematics that is observed in this entire set of rotation curves without the need for any dark matter at all. In previous applications of the theory, a central role was played by a universal linear potential term $V(r)={\gamma }_0{c}^{2}r/2$ that is generated through the effect of cosmology on individual galaxies, with the coefficient ${\gamma }_0=3.06\times {10}^{-30}{\mathrm{cm}}^{-1}$ being of cosmological magnitude. Because the current sample is so big and encompasses some specific galaxies whose data points go out to quite substantial distances from galactic centers, we are able to identify an additional globally induced universal term in the data, a quadratic $V(r)=-\kappa c^2{r}^2/2$ term that is induced by inhomogeneities in the cosmic background. With $\kappa$ being found to be of magnitude $\kappa =9.54\times {10}^{-54}{\mathrm{cm}}^{-2}$, through study of the motions of particles contained within galaxies we are thus able to both detect the presence of a global de Sitter-like component and provide a specific value for its strength. Our study suggests that invoking dark matter may be nothing more than an attempt to describe global physics effects such as these in purely local galactic terms.

We present a new scheme for the general computation of cosmic propagators that allow to interpolate between standard perturbative results at low $k$ and their expected large-$k$ resummed behavior. This scheme is applicable to any multipoint propagator and allows the matching of perturbative low-$k$ calculations to any number of loops to their large-$k$ behavior, and can potentially be applied in case of nonstandard cosmological scenarios such as those with non-Gaussian initial conditions. The validity of our proposal is checked against previous prescriptions and measurements in numerical simulations showing a remarkably good agreement. Such a generic prescription for multipoint propagators provides the necessary building blocks for the computation of polyspectra in the context of the so-called $\Gamma$ expansion introduced by F. Bernardeau, M. Crocce, and R. ScoccimarroPhys. Rev. D 78, 103521 (2008).. As a concrete application we present a consistent calculation of the matter bispectrum at one-loop order.

Relating the forward light-by-light scattering to energy weighted integrals of the ${\gamma }^{*}\gamma$ fusion cross sections, with one real photon ($\gamma$) and one virtual photon (${\gamma }^{*}$), we find two new exact superconvergence relations. They complement the known superconvergence relation based on the extension of the Gerasimov-Drell-Hearn sum rule to the light-light system. We also find a set of sum rules for the low-energy photon-photon interaction. All of the new relations are verified here exactly at leading order in scalar and spinor QED. The superconvergence relations, applied to the ${\gamma }^{*}\gamma$ production of mesons, lead to intricate relations between the $\gamma \gamma$ decay widths or the ${\gamma }^{*}\gamma$ transition form factors for (pseudo)scalar, axial-vector, and tensor mesons. We discuss the phenomenological implications of these results for mesons in both the light-quark sector and the charm-quark sector.

When the classically conformal invariance is imposed on the minimal gauged $B-L$ extended standard model, the $B-L$ gauge symmetry is broken by the Coleman-Weinberg mechanism naturally at the TeV scale. Introducing a new $Z_2$ parity in the model, we investigate phenomenology of a right-handed neutrino dark matter whose stability is ensured by the parity. We find that the relic abundance of the dark matter particle can be consistent with the observations through annihilation processes enhanced by resonances of either the standard model Higgs boson, the $B-L$ Higgs boson, or the $B-L$ gauge boson ($Z^{\prime }$ boson). Therefore, the dark matter mass is close to half of one of these boson masses. Because of the classically conformal invariance and the $B-L$ gauge symmetry breaking via the Coleman-Weinberg mechanism, Higgs boson masses, $Z^{\prime }$ boson mass, and the dark matter mass are all related, and we identify the mass region to be consistent with experimental results. We also calculate the spin-independent cross section of the dark matter particle off with nucleon and discuss implications for future direct dark matter search experiments.

An exploration of the dynamically generated $\Lambda$ and $\Sigma$ resonances has been made in the vector meson-baryon (VB) systems coupled to pseudoscalar meson-baryon (PB) channels. The VB interactions are obtained from the Lagrangians written within the hidden local symmetry which, in addition to Yukawa-type vector-baryon-baryon (VBB) vertices, naturally gives rise to a contact interaction. Using the VBB vertices, we calculate the $t$-, $s$-, and $u$-channel diagrams considering the octet baryon exchange in the latter two cases. For the PB channels we rely on the the Weinberg-Tomozawa interactions and calculate the $\mathrm{PB}\leftrightarrow \mathrm{VB}$ transition amplitudes extending the Kroll-Ruderman theorem by replacing the photon by the vector mesons. In addition to the low-lying $\Lambda (1405)$, $\Lambda (1670)$ found in previous works, we find resonances which coincide well with $\Lambda (2000)$, $\Sigma (1750)S_{11}$, $\Sigma (1940)D_{13}$, $\Sigma (2000)S_{11}$ and predict three ${\Lambda }^{*}$’s with $J^{\pi }=3/2^{-}$ and masses $1754-i2\mathrm{MeV}$, $1862-i33\mathrm{MeV}$, $2139-i14\mathrm{MeV}$ together with a broad $1/2^{-}$ ${\Sigma }^{*}$ with mass $\sim 1430\mathrm{MeV}$. We find that most of these next-to-low-lying states couple weakly with the pseudoscalar mesons, which implies that it is important to study the reactions with VB final states in order to obtain reliable information on the properties of such resonances.

The flux tube model offers a pictorial description of what happens during the deconfinement phase transition in QCD. The three-point vertices of a flux tube network lead to formation of baryons upon hadronization. Therefore, correlations in the baryon number distribution at the last scattering surface are related to the preceding pattern of the flux tube vertices in the quark-gluon plasma, and provide a signature of the nearby deconfinement phase transition. I discuss the nature of the expected signal, and how to extract it from the experimental data for heavy ion collisions at RHIC and LHC.

The extended Lomon-Gari-Krümpelmann model of nucleon electromagnetic form factors, which embodies $\rho$, ${\rho }^{\prime }$, $\omega$, ${\omega }^{\prime }$, and $\varphi$ vector meson contributions and the perturbative QCD high momentum transfer behavior has been extended to the timelike region. Breit-Wigner formulas with momentum-dependent widths have been considered for broad resonances in order to have a parametrization for the electromagnetic form factors that fulfills, in the timelike region, constraints from causality, analyticity, and unitarity. This analytic extension of the Lomon-Gari-Krümpelmann model has been used to perform a unified fit to all the nucleon electromagnetic form factor data, in the spacelike and timelike region (where form factor values are extracted from $e^{+}{e}^{-}\leftrightarrow N\overline{N}$ cross sections data). The knowledge of the complete analytic structure of form factors enables predictions at extended momentum transfer, and also of timelike observables such as the ratio between electric and magnetic form factors and their relative phase.

We study the processes $p\overline{p}\to WZ\to {\ell }^{\pm }\nu {\ell }^{+}{\ell }^{-}$ and $p\overline{p}\to ZZ\to {\ell }^{+}{\ell }^{-}\nu \overline{\nu }$, where $\ell =e$ or $\mu$. Using $8.6{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider, we measure the $WZ$ production cross section to be ${4.50}_{-0.66}^{+0.63}\mathrm{pb}$ which is consistent with, but slightly larger than, the prediction of the standard model. The $ZZ$ cross section is measured to be $1.64\pm 0.46\mathrm{pb}$, in agreement with a prediction of the standard model. Combination with an earlier analysis of the $ZZ\to {\ell }^{+}{\ell }^{-}{\ell }^{+}{\ell }^{-}$ channel yields a $ZZ$ cross section of ${1.44}_{-0.34}^{+0.35}\mathrm{pb}$.

In a paper appearing in this issue of Physical Review D, Burmistrov raises some critical comments on the thermodynamics of a cold tachyon Fermi gas [E. Trojan and G. V. Vlasov, Phys. Rev. D 83, 124013 (2011)]. However, apart from any possible theoretical speculation, there are the basic physical principles to test the theory.

In contrast to Trojan and Vlasov [E. Trojan and G. V. Vlasov, Phys. Rev. D 83, 124013 (2011).], it is found that an ideal Fermi gas of tachyons has a subluminous velocity of sound for any particle density and, therefore, the causality condition for a tachyon gas holds always true. Also, an ideal Fermi gas of tachyons never possesses an exotic equation of state with the pressure exceeding the energy density.

In this paper, we categorize nonrotating black hole spacetimes based on their pole structure, and in each of these categories we determine whether the WKB approximation is a valid approximation for calculating the asymptotic quasinormal modes. We show that Schwarzschild black holes with the Gauss-Bonnet (G-B) correction belong to the category in which the WKB approximation is invalid for calculating these modes. In this context, we further discuss and clarify some of the ambiguity in the literature surrounding a validity condition provided for the WKB approximation.

Using the results of Cacciatori, Klemm, Mansi, and Zorzan [J. High Energy Phys. 05 (2008) 097], where all timelike supersymmetric backgrounds of $\mathcal{N}=2$, $D=4$ matter-coupled supergravity with Fayet-Iliopoulos gauging were classified, we construct genuine NUT-charged BPS black holes in ${\mathrm{\text{anti-de Sitter}}}_4$ with nonconstant moduli. The calculations are exemplified for the $\mathrm{SU}(1,1)/\mathrm{U}(1)$ model with prepotential $F=-i{X}^0{X}^1$. The resulting supersymmetric black holes have a hyperbolic horizon and carry two electric, two magnetic, and one NUT charge, which are however not all independent, but are given in terms of three free parameters. We find that turning on a NUT charge lifts the flat directions in the effective black hole potential, such that the horizon values of the scalars are completely fixed by the charges. We also oxidize the solutions to 11 dimensions, and find that they generalize the geometry found in the work of Gauntlett, Kim, Pakis, and Waldram [Phys. Rev. D 65, 026003 (2001)] corresponding to membranes wrapping holomorphic curves in a Calabi-Yau fivefold. Finally, a class of NUT-charged Nernst branes is constructed as well, but these have curvature singularities at the horizon.

Using the noncommutative deformed canonical commutation relations proposed by Carmona et al. [J. M. Carmona, J. L. Cortés, J. Gamboa, and F. Mendez, J. High Energy Phys. 03 (2003) 058.][J. Gamboa, J. Lopéz-Sarrion, and A. P. Polychronakos, Phys. Lett. B 634, 471 (2006).][J. M. Carmona, J. L. Cortés, Ashok Das, J. Gamboa, and F. Mendez, Mod. Phys. Lett. A 21, 883 (2006).], a model describing the dynamics of the noncommutative complex scalar field is proposed. The noncommutative field equations are solved, and the vacuum energy is calculated to the second order in the parameter of noncommutativity. As an application to this model, the Casimir effect, due to the zero-point fluctuations of the noncommutative complex scalar field, is considered. It turns out that in spite of its smallness, the noncommutativity gives rise to a repulsive force at the microscopic level, leading to a modified Casimir potential with a minimum at the point $a_{\min }=\sqrt{\frac{5}{84}}\pi \theta$.

Modified gravity models such as Hořava-Lifshitz gravity or Einstein-æther theory violate local Lorentz invariance and therefore destroy the notion of a universal light cone. Despite this, in the infrared limit both models above possess static, spherically symmetric solutions with “universal horizons”—hypersurfaces that are causal boundaries between an interior region and asymptotic spatial infinity. In other words, there still exist black hole solutions. We construct a Smarr formula (the relationship between the total energy of the spacetime and the area of the horizon) for such a horizon in Einstein-æther theory. We further show that a slightly modified first law of black hole mechanics still holds with the relevant area now a cross-section of the universal horizon. We construct new analytic solutions for certain Einstein-æther Lagrangians and illustrate how our results work in these exact cases. Our results suggest that holography may be extended to these theories despite the very different causal structure as long as the universal horizon remains the unique causal boundary when matter fields are added.

Using the operator approach, we obtain logarithmic quasinormal modes and frequencies of a traceless spin-3 field around the Bañados-Teitelboim-Zanelli black hole at the critical point of the spin-3 topologically massive gravity. The logarithmic quasinormal frequencies are also confirmed by considering logarithmic conformal field theory.