We present a particularly nice $D$-dimensional graph-based representation of the full color-dressed five-point tree-level gluon amplitude. It possesses the following virtues: (1) it satisfies the color-kinematic correspondence, and thus trivially generates the associated five-point graviton amplitude, (2) all external-state information is encoded in color-ordered partial amplitudes, and (3) one function determines the kinematic contribution of all graphs in the Yang-Mills amplitude, so the associated gravity amplitude is manifestly permutation symmetric. The third virtue, while shared among all known loop-level correspondence-satisfying representations, is novel for tree-level representations sharing the first two virtues. This new $D$-dimensional representation makes contact with the recently found multiloop five-point representations, suggesting all-loop, all-multiplicity ramifications through unitarity. Additionally we present a slightly less virtuous representation of the six-point maximally helicity-violating (MHV) and $\overline{\mathrm{MHV}}$ amplitudes that holds only in four dimensions.

New neutrino states ${\nu }_b$, sterile under the standard model interactions, can be coupled to baryons via the isoscalar vector currents that are much stronger than the standard model weak interactions. If some fraction of solar neutrinos oscillate into ${\nu }_b$ on their way to Earth, the coherently enhanced elastic ${\nu }_b$-nucleus scattering can generate a strong signal in the dark matter detectors. For the interaction strength a few hundred times stronger than the weak force, the elastic ${\nu }_b$-nucleus scattering via new baryonic currents may account for the existing anomalies in the direct detection dark matter experiments at low recoil. We point out that for solar-neutrino energies, the baryon-current-induced inelastic scattering is suppressed, so that the possible enhancement of a new force is not in conflict with signals at dedicated neutrino detectors. We check this explicitly by calculating the ${\nu }_b$-induced deuteron breakup, and the excitation of a 4.4 MeV $\gamma$ line in ${}^{12}\mathrm{C}$. A stronger-than-weak force coupled to the baryonic current implies the existence of a new Abelian gauge group $\mathrm{U}(1{)}_B$ with a relatively light gauge boson.

We consider two-dimensional large $N$ gauge theory with $D$ adjoint scalars on a torus, which is obtained from a $D+2$-dimensional pure Yang-Mills theory on $T^{D+2}$ with $D$ small radii. The two-dimensional model has various phases characterized by the holonomy of the gauge field around noncontractible cycles of the 2-torus. We determine the phase boundaries and derive the order of the phase transitions using a method developed in an earlier work (hep-th/0910.4526), which is nonperturbative in the ’t Hooft coupling and uses a $1/D$ expansion. We embed our phase diagram in the more extensive phase structure of the $D+2$-dimensional Yang-Mills theory and match with the picture of a cascade of phase transitions found earlier in lattice calculations [4]. We also propose a dual gravity system based on a Scherk-Schwarz compactification of a D2 brane wrapped on a 3-torus and find a phase structure which is similar to the phase diagram found in the gauge theory calculation.

Superstring theory and other supersymmetric theories predict the existence of relatively light, weakly interacting scalar particles, called moduli, with a universal form of coupling to matter. Such particles can be emitted from cusps of cosmic strings, where extremely large Lorentz factors are achieved momentarily. Highly boosted modulus bursts emanating from cusps subsequently decay into gluons; they generate parton cascades which in turn produce large numbers of pions and then neutrinos. Because of very large Lorentz factors, extremely high energy neutrinos, up to the Planck scale and above, are produced. For some model parameters, the predicted flux of neutrinos with energies $\gtrsim {10}^{21}\mathrm{eV}$ is observable by JEM-EUSO and by the future large radio detectors LOFAR and SKA.

In this note we examine whether spherically symmetric solutions in covariant Horava-Lifshitz gravity can reproduce Newton’s Law in the IR limit $\lambda \to 1$. We adopt the position that the auxiliary field $A$ is independent of the space-time metric [J. Alexandre and P. Pasipoularides, Phys. Rev. D 83, 084030 (2011).][J. Greenwald, V. H. Satheeshkumar, and A. Wang, J. Cosmol. Astropart. Phys. 12 (2010) 007.], and we assume, as in [A. M. da Silva, Classical Quantum Gravity 28, 055011 (2011).], that $\lambda$ is a running coupling constant. We show that under these assumptions, spherically symmetric solutions fail to restore the standard Newtonian physics in the IR limit $\lambda \to 1$, unless $\lambda$ does not run, and has the fixed value $\lambda =1$. Finally, we comment on the Horava and Melby-Thompson approach [P. Horava and C. M. Melby-Thompson, Phys. Rev. D 82, 064027 (2010).] in which $A$ is assumed as a part of the space-time metric in the IR.

The “no-hair” theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively “frozen in” the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes $N_B=e{\Phi }_{\infty }/(\pi c\hslash )$, where ${\Phi }_{\infty }\approx 2{\pi }^2{B}_{\mathrm{NS}}{R}_{\mathrm{NS}}^3/(P_{\mathrm{NS}}c)$ is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole’s magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.

We assume a $GL(4,R)$ space-time symmetry which is spontaneously broken to $SO(3,1)$. We carry out the coset construction of the effective theory for the nonlinearly realized broken symmetry in terms of the Goldstone fields and matter fields transforming linearly under the unbroken Lorentz subgroup. We then identify functions of the Goldstone and matter fields that transform linearly also under the broken symmetry. Expressed in terms of these quantities the effective theory reproduces the vierbein formalism of general relativity with general coordinate invariance being automatically realized nonlinearly over $GL(4,R)$. The coset construction makes no assumptions about any underlying theory that might be responsible for the assumed symmetry breaking. We give a brief discussion of the possibility of field theories with $GL(4,R)$ rather than Lorentz space-time symmetry providing the underlying dynamics.

If more than one curvaton dominate the Universe at different epochs from each other, curvature perturbations can be temporarily enhanced to a value much larger than the observed one ${10}^{-5}$. The traces of the enhancement may be left as higher order correlation functions, that is, as non-Gaussianity, the stochastic gravitational waves that are sourced by scalar-scalar mode couplings, as well as the primordial black holes that are formed by the gravitational collapse of the enhanced curvature perturbations. We first confirm that such a temporal enhancement indeed occurs by solving the linearized perturbation equations both numerically and analytically. We then derive an analytic expression of the full-order curvature perturbation which does not rely on the frequently used sudden decay approximation and is exact on superhorizon scales. By using this analytic formula, we provide expressions of the nonlinearity parameters $f_{\mathrm{NL}}$, ${\tau }_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$. If both two curvatons contribute to the final curvature perturbations, the strong non-Gaussianity appears in the trispectrum rather than in the bispectrum. We also find a unique consistency relation between ${\tau }_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$ without $f_{\mathrm{NL}}$. By using the second-order perturbation theory, we numerically show that the spectrum of the induced gravitational waves has a plateau corresponding to duration of the enhancement and such gravitational waves can be probed by ultimate-DECIGO and space-based atomic interferometers. We finally calculate the abundance of the primordial black holes and put a constraint on the amplitude of the enhanced curvature perturbations.

In the context of the geometrical analysis of weakly non-Gaussian cosmic microwave background maps, the 2D differential extrema counts as functions of the excursion set threshold is derived from the full moments expansion of the joint probability distribution of an isotropic random field, its gradient, and invariants of the Hessian. Analytic expressions for these counts are given to second order in the non-Gaussian correction, while a Monte Carlo method to compute them to arbitrary order is presented. Matching count statistics to these estimators is illustrated on fiducial non-Gaussian Planck data.

We quantify the effects of the voids known to exist in the Universe upon the reconstruction of the dark energy equation of state $w$. We show that the effect can start to be comparable with some of the other errors taken into account when analyzing supernova data, depending strongly upon the low redshift cutoff used in the sample. For the supernova data alone, the error induced in the reconstruction of $w$ is much larger than the percent level. When the Baryonic Acoustic Oscillations and the Cosmic Microwave Background data are included in the fit, the effect of the voids upon the determination of $w$ is much lessened but is not much smaller than some of the other errors taken into consideration when performing such fits. We also look at the effect of voids upon the estimation of the equation of state when we allow $w$ to vary over time and show that even when supernova, Cosmic Microwave Background, and Baryonic Acoustic Oscillations data are used to constrain the equation of state, the best fit points in parameter space can change at the 10% level due to the presence of voids, and error-bars increase significantly.

We calculated the stress of the quantum vacuum, the Casimir stress, in a spherically symmetric medium, Maxwell’s fish eye, surrounded by a perfect mirror and derived an exact analytic solution. Our solution questions the idea that the Casimir force of a spherical mirror is repulsive—we found an attractive stress in the medium that diverges at the mirror.

Using the most general form of the nucleon interpolating current, we calculate the tensor form factors of the nucleon within light cone QCD sum rules. A comparison of our results on tensor form factors with those of the chiral-soliton model and lattice QCD is given.

We present the distinctive collider signatures of no-scale $\mathcal{F}\mathrm{\text{−}}SU(5)$, a highly efficient and phenomenologically favored model built on the tripodal foundations of the $\mathcal{F}$-lipped $SU(5)\times U(1{)}_{\mathrm{X}}$ grand unified theory, extra $\mathcal{F}$-theory derived TeV scale vectorlike particle multiplets, and the dynamic high-scale boundary conditions of no-scale supergravity. The identifying features of the supersymmetric spectrum are a light stop and gluino, with both sparticles much lighter than all the additional squarks. This unique mass hierarchy leads to the enhanced production of events with an ultrahigh multiplicity of hadronic jets, which should be clearly visible to the $\sqrt{s}=7\mathrm{TeV}$ LHC at only $1{\mathrm{fb}}^{-1}$ of integrated luminosity. We suggest a modest alternative event cutting procedure based around a reduced minimal transverse momentum per jet ($p_{\mathrm{T}}>20\mathrm{GeV}$), and an increased minimal multiplicity ($\ge 9$) of distinct jets per subscribed event. These criteria optimize the $\mathcal{F}\mathrm{\text{−}}SU(5)$ signal-to-background ratio, while readily suppressing the contribution of all standard model processes, allowing moreover a clear differentiation from competing models of new physics, most notably minimal supergravity. The characteristic no-scale signature is quite stable across the viable parameter space, modulo an overall rescaling of the mass spectrum; detection by the LHC of the ultrahigh jet signal would constitute a suggestive evocation of the intimately linked stringy origins of $\mathcal{F}\mathrm{\text{−}}SU(5)$ and could possibly provide a glimpse into the underlying structure of the fundamental string moduli.

We study a warped extra-dimension scenario where the standard model fields lie in the bulk, with the addition of a fourth family of fermions. We concentrate on the flavor structure of the Higgs couplings with fermions in the flavor anarchy ansatz. Even without a fourth family, these couplings will be generically misaligned with respect to the standard model fermion mass matrices. The presence of the fourth family typically enhances the misalignment effects and we show that one should expect them to be highly nonsymmetrical in the (34) intergenerational mixing. The radiative corrections from the new fermions and their flavor-violating couplings to the Higgs affect negligibly known experimental precision measurements such as the oblique parameters and $Z\to b\overline{b}$ or $Z\to {\mu }^{+}{\mu }^{-}$. On the other hand, $\Delta F=1$, 2 processes, mediated by tree-level Higgs exchange, as well as radiative corrections to $b\to s\gamma$ and $\mu \to e\gamma$ put some generic pressure on the allowed size of the flavor-violating couplings. But more importantly, these couplings will alter the Higgs decay patterns as well as those of the new fermions, and produce very interesting new signals associated to Higgs phenomenology in high energy colliders. These signals might become very important indirect signals for these type of models as they would be present even when the KK mass scale is high and no heavy KK particle is discovered.

We investigate the possibility of $\mathrm{U}(1{)}^{\prime }$ mediation, leading to an effective SUSY where the first two family sfermions are above 100 TeV but the third family sfermions and the Higgs doublets are in the TeV region (or the light stop (${\tilde{t}}_l$) case). The $\mathrm{U}(1{)}^{\prime }$ gaugino, Zprimino ($Z^{\prime }$-ino), needs not to be at a TeV scale, but needs to be somewhat lighter than the messenger scale. We consider two cases, one the mediation is only through $\mathrm{U}(1{)}^{\prime }$ and the other through $\mathrm{U}(1{)}^{\prime }$ and the electroweak hypercharge $\mathrm{U}(1{)}_Y$. In the SUSY field theory framework, we calculate the superpartner mass spectra for these two cases. We also point out that the particle species needed for these mechanisms are already obtained from a ${\mathbf{Z}}_{12-I}$ orbifold compactification.

We continue our lattice simulations of QCD with 2 flavors of color-sextet quarks as a model for conformal or walking technicolor. A 2-loop perturbative calculation of the $\beta$ function which describes the evolution of this theory’s running coupling constant predicts that it has a second zero at a finite coupling. This nontrivial zero would be an infrared stable fixed point, in which case the theory with massless quarks would be a conformal field theory. However, if the interaction between quarks and antiquarks becomes strong enough that a chiral condensate forms before this IR fixed point is reached, the theory is QCD-like with spontaneously broken chiral symmetry and confinement. However, the presence of the nearby IR fixed point means that there is a range of couplings for which the running coupling evolves very slowly, i.e. it “walks.” We are simulating the lattice version of this theory with staggered quarks at finite temperature, studying the changes in couplings at the deconfinement and chiral-symmetry restoring transitions as the temporal extent ($N_t$) of the lattice, measured in lattice units, is increased. Our earlier results on lattices with $N_t=4$, 6 show both transitions move to weaker couplings as $N_t$ increases consistent with walking behavior. In this paper we extend these calculations to $N_t=8$. Although both transitions again move to weaker couplings, the change in the coupling at the chiral transition from $N_t=6$ to $N_t=8$ is appreciably smaller than that from $N_t=4$ to $N_t=6$. This indicates that at $N_t=4$, 6 we are seeing strong-coupling effects and that we will need results from $N_t>8$ to determine if the chiral-transition coupling approaches zero as $N_t\to \infty$, as needed for the theory to walk.

Baryon to meson transition distribution amplitudes (TDAs) extend the concept of generalized parton distributions. Baryon to meson TDAs appear as building blocks in the collinear factorized description of amplitudes for a class of hard exclusive reactions, prominent examples of which being hard exclusive meson electroproduction off a nucleon in the backward region and baryon-antibaryon annihilation into a meson and a lepton pair. We study the general properties of these objects following the underlying symmetries of QCD. In particular, the Lorentz symmetry results in the polynomiality property of the Mellin moments in longitudinal momentum fractions. We present a detailed account of the isotopic and permutation symmetry properties of nucleon to pion ($\pi N$) TDAs. This restricts the number of independent leading twist $\pi N$ TDAs to eight functions, providing description of all isotopic channels. Using chiral symmetry and the crossing relation between $\pi N$ TDAs and $\pi N$ generalized distribution amplitudes, we establish soft pion theorems for $\pi N$ TDAs, which determine the magnitude of $\pi N$ TDAs. Finally, we build a simple resonance exchange model for $\pi N$ TDAs considering $N$ and $\Delta (1232)$ exchange contributions into the isospin-$\frac{1}{2}$ and isospin-$\frac{3}{2}$ $\pi N$ TDAs.

The two-particle wave function of neutrino and recoil nucleus is found as a solution of an initial-value problem in the far zone for a time longer than the electron capture decay lifetime of a hydrogenlike ion. The neutrino-recoil entanglement arising in such a process is a consequence of the momentum conservation and is closely related to the wave packet structure of the state. Because of neutrino mixing, the joint wave packet involves the coherent superposition of the neutrino mass eigenstate packets. This is the new physical realization of the Einstein-Podolsky-Rosen thought experiment, which has no analogue in quantum optics and quantum informatics. A class of possible experiments for the registration of a neutrino and a recoil nucleus is proposed. It is shown that, due to spatial correlations, neutrino and recoil oscillations can be observed in the coincidence experiment.

In the type III seesaw model, the heavy neutrinos are contained in leptonic triplet representations. The Yukawa couplings of the triplet fermion and the left-handed neutrinos with the doublet Higgs field produce the Dirac mass terms. Together with the Majorana masses for the leptonic triplets, the light neutrinos obtain nonzero seesaw masses. We point out that it is also possible to have a quadruplet Higgs field to produce the Dirac mass terms to facilitate the seesaw mechanism. The vacuum expectation value of the quadruplet Higgs is constrained to be small by electroweak precision data. Therefore, the Yukawa couplings of a quadruplet can be much larger than those for a doublet. We also find that unlike the usual type III seesaw model where at least two copies of leptonic triplets are needed, with both doublet and quadruplet Higgs representations, just one leptonic triplet is possible to have a phenomenologically acceptable model because light neutrino masses can receive sizable contributions at both tree and one-loop levels. Large Yukawa couplings of the quadruplet can induce observable effects for lepton flavor violating processes $\mu \to e\gamma$ and $\mu -e$ conversion. Implications of the recent $\mu \to e\gamma$ limit from MEG and the limit on $\mu -e$ conversion on Au are also given. Some interesting collider signatures for the doubly charged Higgs boson in the quadruplet are discussed.