On the anatomy of multi-spin magnon and single spike string solutions

We study rigid string solutions rotating in AdS₅×S⁵${\mathit{AdS}}_5\times S^5$ background. For particular values of the parameters of the solutions we find multispin solutions corresponding to giant magnons and single spike strings. We present an analysis of the dispersion relations in the case of three spin solutions distributed only in S⁵$S^5$ and the case of one spin in AdS₅${\mathit{AdS}}_5$ and two spins in S⁵$S^5$. The possible relation of these string solutions to gauge theory operators and spin chains are briefly discussed.     

Exact expressions for quantum corrections to spinning strings

The one-loop worldsheet quantum corrections to the energy of spinning strings on R×S³$\mathbb{R}\times S^3$ within AdS₅×S⁵${\mathit{AdS}}_5\times S^5$ are reexamined. The explicit expansion in the effective 't Hooft coupling λ^′=λ/J²${\lambda }^{\prime }=\lambda /J^2$ is rigorously derived. The expansion contains both analytic and non-analytic terms in λ^′${\lambda }^{\prime }$, as well as exponential corrections. Furthermore, we pin down the origin of the terms that are not captured by the quantum string Bethe ansatz, which only produces analytic terms in λ^′${\lambda }^{\prime }$. It is shown that the analytic terms arise from string fluctuations within the S³$S^3$, whereas the non-analytic and exponential terms, which are not captured by the Bethe ansatz, originate from the fluctuations in all directions within the supersymmetric sigma model on AdS₅×S⁵${\mathit{AdS}}_5\times S^5$. We also comment on the case of spinning string in AdS₃×S¹${\mathit{AdS}}_3\times S^1$.     

Mesons and Higgs branch in defect theories

We consider the defect theory obtained by intersecting D3- and D5-branes along two common spatial directions. We work in the approximation in which the D5-brane is a probe in the AdS₅×S⁵${\mathit{AdS}}_5\times S^5$ background. By adding worldvolume flux to the D5-brane and choosing an appropriate embedding of the probe in AdS₅×S⁵${\mathit{AdS}}_5\times S^5$, one gets a supersymmetric configuration in which some of the D3-branes recombine with the D5-brane. We check this fact by showing that the D5-brane can be regarded as a system of polarized D3-branes. On the field theory side this corresponds to the Higgs branch of the defect theory, where some of the fundamental hypermultiplet fields living on the intersection acquire a vacuum expectation value. We study the spectrum of mesonic bound states of the defect theory in this Higgs branch and show that it is continuous and gapless.     

Some properties of the Alday–Maldacena minimum

The Alday–Maldacena solution, relevant to the n=4$n=4$ gluon amplitude in N=4$N=4$ SYM at strong coupling, was recently identified as a minimum of the regularized action in the moduli space of solutions of the AdS₅${\mathit{AdS}}_5$σ  -model equations of motion. Analogous solutions of the Nambu–Goto equations for the n=4$n=4$ case are presented and shown to form (modulo the reparametrization group) an equally large but different moduli space, with the Alday–Maldacena solution at the intersection of the σ  -model and Nambu–Goto moduli spaces. We comment upon the possible form of the regularized action for n=5$n=5$. A function of moduli parameters za$z_a$ is written, whose minimum reproduces the BDDK one-loop five-gluon amplitude. This function may thus be considered as some kind of Legendre transform of the BDDK formula and has its own value independently of the Alday–Maldacena approach.     

Ricci-flat and charged wormholes in five dimensions

We construct stationary Ricci-flat inter-universe Lorentzian wormhole solutions in all D?5$D?5$ dimensions that connect two flat asymptotic spacetimes. Such a solution can be viewed as the gravity dual of a string tachyon state whose linear momentum is larger than its tension. We focus our analysis on the D=5$D=5$ wormholes which are not traversable for the timelike and null geodesics; however, we demonstrate that there exist accelerated timelike trajectories that traverse from one asymptotic region to the other. We further study the minimally-coupled scalar wave equation and demonstrate that the quantum tunnelling between two worlds must occur. We also obtain charged wormholes in five-dimensional supergravities. With appropriate choice of parameters, these wormholes connect AdS₃×S²${\mathit{AdS}}_3\times S^2$ in one asymptotic region to flat Minkowskian spacetime in the other.     

Galilean anti-de-Sitter spacetime in Romans theory

The Romans type IIA theory is the only known example of 10-dimensional maximal supergravity where (tensor) fields are explicitly massive. We provide an example of a non-relativistic anti-de-Sitter NRadS₄×S⁶${\mathit{NRadS}}_4\times S^6$ background as a solution in massive type IIA. A compactification of which on S⁶$S^6$ gives immediately the prototype NRadS background in D=4$D=4$ which is proposed to be dual to ‘cold atoms’ or unitary fermions on a wire.     

Searching for an extra neutral gauge boson from muon pair production at LHC

We search for signatures of the extra neutral gauge boson Z^′$Z^{\prime }$, predicted in some extensions of the Standard Model, from the analysis of some distributions for p+p→μ⁺+μ⁻+X$p+p\to {\mu }^{+}+{\mu }^{-}+X$, where the only exotic particle involved is Z^′$Z^{\prime }$. In addition to the invariant mass and charge asymmetry distributions, we propose in our search to use the transverse momentum distribution (pT$p_T$) as an observable. We do our calculation for two values of the LHC center of mass energy (7 and 14 TeV), corresponding to 1 and 100 fb⁻¹ of luminosity, in order to compare our findings from some models with the distributions following from the Standard Model. By applying convenient cuts in the invariant mass, we show that the final particles pT$p_T$ distributions can reveal the presence of an extra neutral gauge boson contribution. We also claim that it is possible to disentangle the models considered here and we emphasize that the minimal version of the model, based on SUC₍₃₎×SUL₍₃₎×UX₍₁₎$\mathit{SU}{(3)}_C\times \mathit{SU}{(3)}_L\times U{(1)}_X$ symmetry, presents the more clear signatures for Z^′$Z^{\prime }$ existence.     

Entropy of an extremal regular black hole

We introduce a magnetically charged extremal regular black hole in the coupled system of Einstein gravity and nonlinear electrodynamics. Its near horizon geometry is given by AdS₂×S²${\mathit{AdS}}_2\times S^2$. It turns out that the entropy function approach does not automatically lead to a correct entropy of the Bekenstein–Hawking entropy. This contrasts to the case of the extremal Reissner–Norström black hole in the Einstein–Maxwell theory. We conclude that the entropy function approach does not work for a magnetically charged extremal regular black hole without singularity, because of the nonlinearity of the entropy function.     

Ultraviolet behaviour of higher spin gauge field propagators and one loop mass renormalization

The ultraviolet singular structure of the bulk-to-bulk propagators for higher spin gauge fields in AdS₄${\mathit{AdS}}_4$ space is analyzed in details. Possible interactions with the Higgs scalar and the corresponding one loop mass renormalization are studied. This mass renormalization is finite and connected with the anomalous dimensions of those currents in the corresponding boundary CFT₃${\mathit{CFT}}_3$ that cease to be conserved when the interaction is switched on. In particular it is proportional to ?−2$?-2$.     

A note on embedding non-Abelian finite flavor groups in continuous groups

A non-Abelian finite flavor group G⊂SO(3)$G\subset \mathit{SO}(3)$ can have double covering G^′⊂SU(2)$G^{\prime }\subset \mathit{SU}(2)$ such that G⊄G^′$G\not\subset G^{\prime }$. This situation is not contradictory, but quite natural, and we give explicit examples such as G=Dn$G=D_n$, G^′=Q_2n$G^{\prime }=Q_{2n}$ and G=T$G=T$, G^′=T^′$G^{\prime }=T^{\prime }$. This observation can be crucial in particle theory model building.     

Two-dimensional gauge theory and matrix model

We study a matrix model obtained by dimensionally reducing Chern–Simons theory on S³$S^3$. We find that the matrix integration is decomposed into sectors classified by the representation of SU(2)$\mathit{SU}(2)$. We show that the N  -block sectors reproduce SU(N)$\mathit{SU}(N)$ Yang–Mills theory on S²$S^2$ as the matrix size goes to infinity.     

Shot noise in HTc superconductor quantum point contact system

We study the electrical transport properties of a quantum point contact between a lead and a high Tc superconductor. For this, we use the Hamiltonian approach and non-equilibrium Green functions of the system. The electrical current and the shot noise are calculated with this formalism. We consider d_x²−y²${\mathrm{d}}_{x^2-y^2}$, d_xy${\mathrm{d}}_{\mathit{xy}}$, d_x²−y²+is${\mathrm{d}}_{x^2-y^2}+\mathrm{is}$ and d_xy+is${\mathrm{d}}_{\mathit{xy}}+\mathrm{is}$ symmetries for the pair potential. Also we explore the s₊₋${\mathrm{s}}_{+-}$ and s₊₊${\mathrm{s}}_{++}$ symmetries describing the behavior of the ferropnictides superconductors. We found that for d_xy${\mathrm{d}}_{\mathit{xy}}$ symmetry there is not a zero bias conductance peak and for d+is$\mathrm{d}+\mathrm{is}$ symmetries there is a displacement of the transport properties. From shot noise and current, the Fano factor is calculated and we found that it takes values of effective charge between e and 2e  , this is explained by the diffraction of quasiparticles in the contact. For the s₊₋${\mathrm{s}}_{+-}$ and s₊₊${\mathrm{s}}_{++}$ symmetries the results show that the electrical current and the shot noise depend on the mixing coefficient, furthermore, the effective electric charge can take values between 0 and 2e, in contrast with the results obtained for s wave superconductors.     

Eikonal contributions to ultra high energy neutrino–nucleon cross sections in low scale gravity models

We calculate low scale gravity effects on the cross section for neutrino–nucleon scattering at center of mass energies up to the Greisen–Zatsepin–Kuzmin (GZK) scale, in the eikonal approximation. We compare the cases of an infinitely thin brane embedded in n=5$n=5$ compactified extra-dimensions, and of a brane with a physical tension MS=1 TeV$M_S=1\text{TeV}$ and MS=10 TeV$M_S=10\text{TeV}$. The extra dimensional Planck scale MD$M_D$ is set at ¹⁰³ GeV${10}^3\text{GeV}$ and 2×¹⁰³ GeV$2\times {10}^3\text{GeV}$. We also compare our calculations with neutral current standard model calculations in the same energy range, and compare the thin brane eikonal cross section to its saddle point approximation. New physics effects enhance the cross section by orders of magnitude on average. They are quite sensitive to MS$M_S$ and MD$M_D$ choices, though much less sensitive to n.     

Integrability lost: Chaotic dynamics of classical strings on a confining holographic background

It is known that classical string dynamics on pure AdS₅×S⁵${\mathit{AdS}}_5\times S^5$ is integrable and plays an important role in solvability. This is a deep and central issue in holography. Here we investigate similar classical integrability for a more realistic confining background and provide a negative answer. The dynamics of a class of simple string configurations on AdS soliton background can be mapped to the dynamics of a set of non-linearly coupled oscillators. In a suitable limit of small fluctuations we discuss a quasi-periodic analytic solution of the system. Numerics indicates chaotic behavior as the fluctuations are not small. Integrability implies the existence of a regular foliation of the phase space by invariant manifolds. Our numerics shows how this nice foliation structure is eventually lost due to chaotic motion. We also verify a positive Lyapunov index for chaotic orbits. Our dynamics is roughly similar to other known non-integrable coupled oscillator systems like Hénon–Heiles equations.