We discuss a robust projection method for the extraction of excited-state masses of the nucleon from a matrix of correlation functions. To illustrate the algorithm in practice, we present results for the positive parity excited states of the nucleon in quenched QCD. Using eigenvectors obtained via the variational method, we construct an eigenstate-projected correlation function amenable to standard analysis techniques. The method displays its utility when comparing results from the fit of the projected correlation function with those obtained from the eigenvalues of the variational method. Standard nucleon interpolators are considered, with $2\times 2$ and $3\times 3$ correlation matrix analyses presented using various combinations of source-smeared, sink-smeared, and smeared-smeared correlation functions. Using these new robust methods, we observe a systematic dependency of the extracted nucleon excited-state masses on source- and sink-smearing levels. To the best of our knowledge, this is the first clear indication that a correlation matrix of standard nucleon interpolators is insufficient to isolate the eigenstates of QCD.

We investigate the model dependence of no-helicity flip generalized parton distribution of the pion upon different approaches for the quark-hadron and quark-photon vertices, in the spacelike region. In order to obtain information on contributions from both the valence and the nonvalence regions, we compare results for spacelike momentum transfers obtained from (i) an analytic covariant model with a bare quark-photon vertex, (ii) a light-front approach with a quark-photon vertex dressed through a microscopic vector-meson model, and (iii) a light-front approach based on the relativistic Hamiltonian dynamics. Our comparisons lead us to infer the same dynamical mechanism, the one-gluon-exchange dominance at short distances, as a source of both the electromagnetic form factor at large momentum transfer and the parton distribution close to the end points. The expected collinear behavior of the generalized parton distributions at high-momentum transfer, i.e. a maximum for $x\sim 1$, is also illustrated, independently of the different approaches. Finally, a comparison with recent lattice calculations of the gravitational form factors is presented.

Electron-positron pair production in combined laser and Coulomb fields is studied. To this end, the Feynman diagram for multiphoton pair creation by muon impact on a circularly polarized high-frequency laser beam is evaluated within the framework of laser-dressed quantum electrodynamics employing relativistic Volkov states. In the limit of low laser intensity, the result is shown to coincide with the known expression for multiphoton pair creation by a proton which is treated as an external Coulomb field. A scaling of the total pair creation rate is analyzed. The recoil distribution is calculated numerically and its dependence on the projectile mass and the number of absorbed photons is discussed. Angular spectra of the scattered muon, as well as energy spectra of the created particles and the correlation between the produced particles’ emission angles, are presented.

We investigate in a model-independent way to what extent one can perturb tribimaximal mixing in order to generate a sizable value of $|U_{e3}|$, while at the same time keeping solar neutrino mixing near its measured value, which is close to ${sin}^2{\theta }_{12}=\frac{1}{3}$. Three straightforward breaking mechanisms to generate $|U_{e3}|\simeq 0.1$ are considered. For charged lepton corrections, the suppression of a sizable contribution to ${sin}^2{\theta }_{12}$ can be achieved if $CP$ violation in neutrino oscillations is almost maximal. Generation of the indicated value of $|U_{e3}|\simeq 0.1$ through renormalization group corrections requires the neutrinos to be quasidegenerate in mass. The consistency with the allowed range of ${sin}^2{\theta }_{12}$ together with large running of $|U_{e3}|$ forces one of the Majorana phases to be close to $\pi$. This implies large cancellations in the effective Majorana mass governing neutrinoless double beta ($(\beta \beta {)}_{0\nu }$) decay, constraining it to lie near its minimum allowed value of $m_0\cos 2{\theta }_{12}$, where $m_0\gtrsim 0.1\mathrm{eV}$. Finally, explicit breaking of the neutrino mass matrix in the inverted hierarchical and quasidegenerate neutrino mass spectrum cases is similarly correlated with the $(\beta \beta {)}_{0\nu }$-decay effective Majorana mass, although to a lesser extent. The implied values for the atmospheric neutrino mixing angle ${\theta }_{23}$ are given in all cases.

We present a direct measurement of trilinear gauge boson couplings at $\gamma WW$ and $ZWW$ vertices in $WW$ and $WZ$ events produced in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. We consider events with one electron or muon, missing transverse energy, and at least two jets. The data were collected using the D0 detector and correspond to $1.1{\mathrm{fb}}^{-1}$ of integrated luminosity. Considering two different relations between the couplings at the $\gamma WW$ and $ZWW$ vertices, we measure these couplings at 68% C.L. to be ${\kappa }_{\gamma }={1.07}_{-0.29}^{+0.26}$, $\lambda ={0.00}_{-0.06}^{+0.06}$, and $g_1^Z={1.04}_{-0.09}^{+0.09}$ in a scenario respecting $SU(2{)}_L\otimes U(1{)}_Y$ gauge symmetry and $\kappa ={1.04}_{-0.11}^{+0.11}$ and $\lambda ={0.00}_{-0.06}^{+0.06}$ in an “equal couplings” scenario.

Using $e^{+}{e}^{-}\to D_s^{-}{D}_s^{*+}$ and $D_s^{*-}{D}_s^{+}$ interactions at 4170 MeV collected with the CLEO-c detector, we investigate the semileptonic decays $D_s^{+}\to f_0(980)e^{+}\nu$ and $D_s^{+}\to \varphi e^{+}\nu$. By examining the decay rates as functions of the four-momentum transfer squared $q^2$, we measure the ratio $[\frac{d\mathcal{B}}{d{q}^2}(D_s^{+}\to f_0(980)e^{+}\nu )\mathcal{B}(f_0\to {\pi }^{+}{\pi }^{-})]/[\frac{d\mathcal{B}}{d{q}^2}(D_s^{+}\to \varphi e^{+}\nu )\mathcal{B}(\varphi \to K^{+}{K}^{-})]$ at $q^2$ of zero to be $(42\pm 11)\%$. This ratio has been predicted to equal the rate ratio $[\mathcal{B}(B_s\to J/\psi f_0)\mathcal{B}(f_0\to {\pi }^{+}{\pi }^{-})]/[\mathcal{B}(B_s\to J/\psi \varphi )\mathcal{B}(\varphi \to K^{+}{K}^{-})]$, thus indicating that the $CP$ eigenstate $J/\psi f_0$ could be useful for measuring $CP$ violation via $B_s$ mixing. Assuming a simple pole model for the form factor $|f_{+}(q^2)|$ in the $f_0{e}^{+}\nu$ decay, we find a pole mass of $({1.7}_{-0.7}^{+4.5}\pm 0.2)\mathrm{GeV}$. We also determine the $f_0$ mass and width as $({977}_{-9}^{+11}\pm 1)$ and $({91}_{-22}^{+30}\pm 3)\mathrm{MeV}$, respectively. In addition, we present updated results for $\mathcal{B}(D_s^{+}\to f_0(980)e^{+}\nu )\mathcal{B}(f_0\to {\pi }^{+}{\pi }^{-})=(0.20\pm 0.03\pm 0.01)\%$ and $\mathcal{B}(D_s^{+}\to \varphi e^{+}\nu )=(2.36\pm 0.23\pm 0.13)\%$. Assuming that the $f_0$ wave function is a combination of strange and nonstrange quark-antiquark components, we use our measurement for $\mathcal{B}(D_s^{+}\to f_0(980)e^{+}\nu )$ to extract a value of the mixing angle that we find consistent with $\mid \overline{s}s⟩$ dominance, adding to the mystery as to why the $f_0$ decays predominantly to two pions rather than two kaons.

$D=11$ supergravity near a spacelike singularity admits a cosmological billiard description based on the hyperbolic Kac-Moody group $E_{10}$. The quantization of this system via the supersymmetry constraint is shown to lead to wave functions involving automorphic (Maass wave) forms under the modular group $W^{+}(E_{10})\cong PS{L}_2(\mathtt{O})$ with Dirichlet boundary conditions on the billiard domain. A general inequality for the Laplace eigenvalues of these automorphic forms implies that the wave function of the Universe is generically complex and always tends to zero when approaching the initial singularity. We discuss possible implications of this result for the question of singularity resolution in quantum cosmology and comment on the differences with other approaches.

A new quark-field smearing algorithm is defined which enables efficient calculations of a broad range of hadron correlation functions. The technique applies a low-rank operator to define smooth fields that are to be used in hadron creation operators. The resulting space of smooth fields is small enough that all elements of the reduced quark propagator can be computed exactly at reasonable computational cost. Correlations between arbitrary sources, including multihadron operators can be computed a posteriori without requiring new lattice Dirac operator inversions. The method is tested on realistic lattice sizes with light dynamical quarks.

The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a ${20}^3\times 40$ lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-$3/2$ baryons, including the electric-quadrupole moment $E2$ and the magnetic-octupole moment $M3$. The world’s first determination of a nonzero $M3$ form factor for the $\Delta$ baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish that the environment sensitivity is far less pronounced for the decuplet baryons compared to the octet baryons. A surprising result is that the charge radii of the decuplet baryons are generally smaller than those of the octet baryons. The magnetic moment of the ${\Delta }^{+}$ reveals a turnover in the low quark-mass region, making it smaller than the proton magnetic moment. These results are consistent with the expectations of quenched chiral perturbation theory. A similar turnover is also noticed in the magnetic moment of the ${\Sigma }^{*0}$, but not for ${\Xi }^{*}$ where only kaon loops can appear in quenched QCD. The electric-quadrupole moment of the ${\Omega }^{-}$ baryon is positive when the negative charge factor is included, and is equal to $0.86\pm 0.12\times {10}^{-2}{\mathrm{fm}}^2$, indicating an oblate shape.

This work is based on an earlier proposal [H. Singh, Phys. Lett. B 673, 68 (2009)] that the membrane BF theory consists of matter fields along with Chern-Simons fields as well as the auxiliary pairs of scalar and tensor fields. In particular, we discuss the supersymmetry aspects of such a membrane theory. It is concluded that the theory possesses maximal supersymmetry, and it is related to the L-BLG theory via a field map. We obtain fuzzy-sphere solution, and corresponding tensor field configuration is given.

We show at one loop and first order in the noncommutativity parameters that in any noncommutative GUT inspired theory the total contribution to the fermionic four point functions coming only from the interaction between fermions and gauge bosons, though not UV finite by power counting, is UV finite at the end of the day. We also show that this is at odds with the general case for noncommutative gauge theories—chiral or otherwise—defined by means of Seiberg-Witten maps that are the same—barring the gauge group representation—for left-handed spinors as for right-handed spinors. We believe that the results presented in this paper tilt the scales to the side of noncommutative GUTS and noncommutative GUT inspired versions of the standard model.

Proceeding from nonlinear realizations of (super)conformal symmetries, we explicitly demonstrate that adding the harmonic oscillator potential to the action of conformal mechanics does not break these symmetries but modifies the transformation properties of the (super)fields. We also analyze the possibility to introduce potentials in $N=4$ supersymmetric mechanics by coupling it with auxiliary fermionic superfields. The new coupling we considered does not introduce new fermionic degrees of freedom—all our additional fermions are purely auxiliary ones. The new bosonic components have a first order kinetic term and therefore they serve as spin degrees of freedom. The resulting system contains, besides the potential term in the bosonic sector, a nontrivial spinlike interaction in the fermionic sector. The superconformal mechanics we constructed in this paper is invariant under the full $D(2,1;\alpha )$ superconformal group. This invariance is not evident and is achieved within modified (super)conformal transformations of the superfields.

We derive sum rules involving the spectral density of the stress-energy tensor in $\mathcal{N}=4$ super-Yang-Mills theory and pure Yang-Mills theory. The sum rules come from the hydrodynamic behavior at small momenta and the conformal (in the case of $\mathcal{N}=4$ super-Yang-Mills theory) or asymptotically free (as for the pure Yang-Mills theory) behavior at large momenta. These sum rules may help constrain quark-gluon plasma transport coefficients obtained from lattice QCD.

A three-parameter (positive odd integer $s$, thickness factor $\lambda$, and asymmetry factor $a$) family of asymmetric thick brane solutions in five dimensions were constructed from a two-parameter ($s$ and $\lambda$) family of symmetric ones in by R. Guerrero, R. O. Rodriguez, and R. Torrealba in [Phys. Rev. D 72, 124012 (2005).]. The values $s=1$ and $s\ge 3$ correspond to single branes and double branes, respectively. These branes have very rich inner structure. In this paper, by presenting the mass-independent potentials of Kaluza-Klein (KK) modes in the corresponding Schrödinger equations, we investigate the localization and mass spectra of fermions on the symmetric and asymmetric thick branes in an anti-de Sitter background. In order to analyze the effect of gravity-fermion interaction (i.e., the effect of the inner structure of the branes) and scalar-fermion interaction to the spectrum of fermion KK modes, we consider three kinds of typical kink-fermion couplings. The spectra of left chiral fermions for these couplings consist of a bound zero mode and a series of gapless continuous massive KK modes, some discrete bound KK modes including zero mode (exist mass gaps), and a series of continuous massive KK modes, infinite discrete bound KK modes, respectively. The structures of the spectra are investigated in detail.

We find the propagator and calculate the tree level scattering amplitude between two covariantly conserved sources in an anti–de Sitter background for the most general $D$-dimensional quadratic, four-derivative, gravity with a Pauli-Fierz mass. We also calculate the Newtonian potential for various limits of the theory in flat space. We show how the recently introduced three-dimensional New Massive Gravity is uniquely singled out among higher derivative models as a (tree level) unitary model and that its Newtonian limit is equivalent to that of the usual massive gravity in flat space.

The Laser Interferometer Space Antenna (LISA) defines new demands on data analysis efforts in its all-sky gravitational wave survey, recording simultaneously thousands of galactic compact object binary foreground sources and tens to hundreds of background sources like binary black hole mergers and extreme-mass ratio inspirals. We approach this problem with an adaptive and fully automatic Reversible Jump Markov Chain Monte Carlo sampler, able to sample from the joint posterior density function (as established by Bayes theorem) for a given mixture of signals “out of the box”, handling the total number of signals as an additional unknown parameter beside the unknown parameters of each individual source and the noise floor. We show in examples from the LISA Mock Data Challenge implementing the full response of LISA in its TDI description that this sampler is able to extract monochromatic Double White Dwarf signals out of colored instrumental noise and additional foreground and background noise successfully in a global fitting approach. We introduce 2 examples with fixed number of signals (MCMC sampling), and 1 example with unknown number of signals (RJ-MCMC), the latter further promoting the idea behind an experimental adaptation of the model indicator proposal densities in the main sampling stage. We note that the experienced runtimes and degeneracies in parameter extraction limit the shown examples to the extraction of a low but realistic number of signals.

We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke’s discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.

We numerically study the event horizons of two kinds of five-dimensional coalescing black hole solutions with different asymptotic structures: the five-dimensional Kastor-Traschen solution (5DKT) and the coalescing black hole solution on Eguchi-Hanson space (CBEH). Topologies of the spatial infinity are ${\mathrm{S}}^3$ and $L(2;1)={\mathrm{S}}^3/{\mathbb{Z}}_2$, respectively. We show that the crease sets of event horizons are topologically ${\mathrm{R}}^1$ in 5DKT and ${\mathrm{R}}^1\times {\mathrm{S}}^1$ in CBEH, respectively. If we choose the time slices that respect space-time symmetry, the first contact points of the coalescing process is a point in the 5DKT case but a ${\mathrm{S}}^1$ in the CBEH case. We also find that in CBEH, time slices can be chosen so that a black ring with ${\mathrm{S}}^1\times {\mathrm{S}}^2$ topology can be also formed during a certain intermediate period unlike the 5DKT.

The tidal interaction of a (rotating or nonrotating) black hole with nearby bodies produces changes in its mass, angular momentum, and surface area. Similarly, tidal forces acting on a Newtonian, viscous body do work on the body, change its angular momentum, and part of the transferred gravitational energy is dissipated into heat. The equations that describe the rate of change of the black-hole mass, angular momentum, and surface area as a result of the tidal interaction are compared with the equations that describe how the tidal forces do work, torque, and produce heat in the Newtonian body. The equations are strikingly similar, and unexpectedly, the correspondence between the Newtonian-body and black-hole results is revealed to hold in near-quantitative detail. The correspondence involves the combination $k_2\tau$ of “Love quantities” that incorporate the details of the body’s internal structure; $k_2$ is the tidal Love number, and $\tau$ is the viscosity-produced delay between the action of the tidal forces and the body’s reaction. The combination $k_2\tau$ is of order $GM/c^3$ for a black hole of mass $M$; it does not vanish, in spite of the fact that $k_2$ is known to vanish individually for a nonrotating black hole.