Table of contents

We present a complete treatment of the diffusion processes for supersymmetric electroweak baryogenesis that characterizes transport dynamics ahead of the phase transition bubble wall within the symmetric phase. In particular, we generalize existing approaches to distinguish between chemical potentials of particles and their superpartners. This allows us to test the assumption of superequilibrium (equal chemical potentials for particles and sparticles) that has usually been made in earlier studies. We show that in the Minimal Supersymmetric Standard Model, superequilibrium is generically maintained — even in the absence of fast supergauge interactions — due to the presence of Yukawa interactions. We provide both analytic arguments as well as illustrative numerical examples. We also extend the latter to regions where analytical approximations are not available since down-type Yukawa couplings or supergauge interactions only incompletely equilibrate. We further comment on cases of broken superequilibrium wherein a heavy superpartner decouples from the electroweak plasma, causing a kinematic bottleneck in the chain of equilibrating reactions. Such situations may be relevant for baryogenesis within extensions of the MSSM. We also provide a compendium of inputs required to characterize the symmetric phase transport dynamics.

We study the stochastic motion of a relativistic trailing string in black hole AdS₅. The classical string solution develops a world-sheet horizon and we determine the associated Hawking radiation spectrum. The emitted radiation causes fluctuations on the string both above and below the world-sheet horizon. In contrast to standard black hole physics, the fluctuations below the horizon are causally connected with the boundary of AdS. We derive a bulk stochastic equation of motion for the dual string and use the AdS/CFT correspondence to determine the evolution of a fast heavy quark in the strongly coupled = 4 plasma. We find that the kinetic mass of the quark decreases by ΔM = −(γλ)^1/2T/2 while the correlation time of world sheet fluctuations increases by γ^1/2.

We provide a dual gravity description of a supersymmetric heavy nucleus, following the idea of our previous paper arXiv/0809.3141. The supersymmetric nucleus consists of a merginal bound state of A baryons distributed over a ball in 3 dimensions. In the gauge/string duality, the baryon in = 4 super Yang-Mills (SYM) theory corresponds to a D5-brane wrapping S⁵ of the AdS₅×S⁵ spacetime, so the nucleus corresponds to a collection of A D5-branes. We take a large A and a near horizon limits of a back-reacted geometry generated by the wrapped A D5-branes, where we find a gap in the supergravity fluctuation spectrum. This spectrum is a gravity dual of giant resonances of heavy nuclei, in the supersymmetric toy example of QCD.

A linear stability analysis of twisted flux-tubes (strings) in an SU(2) semilocal theory — an Abelian-Higgs model with two charged scalar fields with a global SU(2) symmetry — is carried out. Here the twist refers to a relative phase between the two complex scalars (with linear dependence on, say, the z coordinate), and importantly it leads to a global current flowing along the the string. Such twisted strings bifurcate with the Abrikosov-Nielsen-Olesen (ANO) solution embedded in the semilocal theory. Our numerical investigations of the small fluctuation spectrum confirm previous results that twisted strings exhibit instabilities whose amplitudes grow exponentially in time. More precisely twisted strings with a single magnetic flux quantum admit a continuous family of unstable eigenmodes with harmonic z dependence, indexed by a wavenumber k∊[−k_m, k_m]. Carrying out a perturbative semi-analytic analysis of the bifurcation, it is found that the purely numerical results are very well reproduced. This way one obtains not only a good qualitative description of the twisted solutions themselves as well as of their instabilities, but also a quantitative description of the numerical results. Our semi-analytic results indicate that in close analogy to the known instability of the embedded ANO vortex a twisted string is also likely to expand in size caused by the spreading out of its magnetic flux.

We perform a systematic analysis of globally consistent D-brane quivers which realize the MSSM and analyze them with respect to their Yukawa couplings. Often, desired couplings are perturbatively forbidden due to the presence of global U(1) symmetries. We investigate the conditions under which D-brane instantons will induce these missing couplings without generating other phenomenological drawbacks, such as R-parity violating couplings or a μ-term which is too large. Furthermore, we systematically analyze which quivers allow for a mechanism that can account for the small neutrino masses and other experimentally observed hierarchies. We show that only a small fraction of the globally consistent D-brane quivers exhibits phenomenology compatible with experimental observations.

Starting from the semiclassical reduced-action approach to transplanckian scattering by Amati, Veneziano and one of us and from our previous quantum extension of that model, we investigate theS-matrix expression for inelastic processes by extending to this case the tunneling features previously found in the region of classical gravitational collapse. The resulting model exhibits some non-unitary S-matrix eigenvalues for impact parameters b < b_c, a critical value of the order of the gravitational radiusR = 2Gs^1/2, thus showing that some (inelastic) unitarity defect is generally present, and can be studied quantitatively. We find that S-matrix unitarity for b < b_c is restored only if the rapidity phase-space parameter y is allowed to take values larger than the effective coupling Gs/ℏ itself. Some features of the resulting unitary model are discussed.

We compute one-loop corrections to the S and T parameters in the Unhiggs scenario. In that scenario, the Standard Model Higgs is replaced by a non-local object, called the Unhiggs, whose spectral function displays a continuum above the mass gap. The Unhiggs propagator has effectively the same UV properties as the Standard Model Higgs propagator, which implies that loop corrections to the electroweak precision observables are finite and calculable. We show that the Unhiggs is consistent with electroweak precision tests when its mass gap is at the weak scale; in fact, it then mimics a light SM Higgs boson. We also argue that the Unhiggs, while being perfectly visible to electroweak precision observables, is invisible to detection at LEP.

We propose, using the example of the O(4) sigma model, a general method for solving integrable two dimensional relativistic sigma models in a finite size periodic box. Our starting point is the so-called Y-system, which is equivalent to the thermodynamic Bethe ansatz equations of Yang and Yang. It is derived from the Zamolodchikov scattering theory in the cross channel, for virtual particles along the non-compact direction of the space-time cylinder. The method is based on the integrable Hirota dynamics that follows from the Y-system. The outcome is a nonlinear integral equation for a single complex function, valid for an arbitrary quantum state and accompanied by the finite size analogue of Bethe equations. It is close in spirit to the Destri-deVega (DdV) equation. We present the numerical data for the energy of various states as a function of the size, and derive the general Lüscher-type formulas for the finite size corrections. We also re-derive by our method the DdV equation for the SU(2) chiral Gross-Neveu model.

We construct a new classical solution in the ABJM theory corresponding to M5-branes with a non-zero self-dual three-form flux. This is an M-theory lift of the D4-brane solution expressed as a non-commutative plane in the three dimensional super Yang-Mills theory. We discuss that our solution is closely related with the three-algebra. We show that the corresponding configuration of the M5-brane satisfies the equations of motion in the single M5-brane action. We find the agreement between the tension of the M5-brane solution in the ABJM action and the one computed from the single M5-brane action.

If Micro Black Holes (MBHs) can be produced at the LHC, they will decay very fast. We study hypothetical MBHs that do not decay; in particular, QCD effects on accretion by MBHs that are produced at rest. We explain why accretion of a nucleon by such MBHs is associated with pion emission. This pion emission results in a kick to the MBHs, such that their velocities are large enough to escape the Earth. Our study provides an extra assurance that MBHs which might be produced at the LHC are not dangerous.

We study flavour violation in a supersymmetric SO(10) implementation of the type II seesaw mechanism, which provides a predictive realization of triplet leptogenesis. The experimental upper bounds on lepton flavour violating processes have a significant impact on the leptogenesis dynamics, in particular they exclude the strong washout regime. Requiring successful leptogenesis then constrains the otherwise largely unknown overall size of flavour-violating observables, thus yielding testable predictions. In particular, the branching ratio for μ → eγ lies within the reach of the MEG experiment if the superpartner spectrum is accessible at the LHC, and the supersymmetric contribution to ε_K can account for a significant part of the experimental value. We show that this scenario can be realized in a consistent SO(10) model achieving gauge symmetry breaking and doublet-triplet splitting in agreement with the proton decay bounds, improving on the MSSM prediction for α₃(m_Z), and reproducing the measured quark and lepton masses.

We calculate the bulk viscosity, drag force and jet quenching parameter in Improved Holographic QCD. We find that the bulk viscosity rises near the phase transition but does not exceed the shear viscosity. The drag force shows the effects of asymptotic freedom both as a function of velocity and temperature. It indicates diffusion times of heavy quarks in rough agreement with data. The jet quenching parameter values computed via the light-like Wilson loop are in the lower range suggested by data.

We explore the possibility of a new dark matter candidate in the supersymmetric type III seesaw mechanism where a neutral scalar component of the Y = 0 triplet can be the lightest supersymmetric particle. Its thermal abundance can be in the right range if non-standard cosmology such as kination domination is assumed. The enhanced cross-section of the dark matter annihilation to W⁺W⁻ can leave detectable astrophysical and cosmological signals whose current observational data puts a lower bound on the dark matter mass. The model predicts the existence of a charged scalar almost degenerate with the dark matter scalar and its lifetime lies between 5.5 cm and 6.3 m. It provides a novel opportunity of the dark mater mass measurement by identifying slowly-moving and highly-ionizing tracks in the LHC experiments. If the ordinary lightest supersymmetric particle is the usual Bino, its decay leads to clean signatures of same-sign dilepton and di-charged-scalar associated with observable displaced vertices which are essentially background-free and can be fully reconstructed.

We study a Δ(54) × Z₂ flavor model for leptons and sleptons. The tri-bimaximal mixing can be reproduced for arbitrary neutrino masses if certain vacuum alignments of scalar fields are realized. The deviation from the tri-bimaximal mixing of leptons is predicted. The predicted upper bound for sin θ₁₃ is 0.07. The value of sin θ₂₃ could be deviated from the maximal mixing considerably while sin θ₁₂ is hardly deviated from 1/√3. We also study SUSY breaking terms in the slepton sector. Three families of left-handed and right-handed slepton masses are almost degenerate. Our model leads to smaller values of flavor changing neutral currents than the present experimental bounds.

In [1] we explained that partition functions of various matrix models can be constructed from that of the cubic Kontsevich model, which, therefore, becomes a basic elementary building block in "M-theory" of matrix models [2]. However, the less topical complex matrix model appeared to be an exception: its decomposition involved not only the Kontsevich τ-function but also another constituent, which we now identify as the Brezin-Gross-Witten (BGW) partition function. The BGW τ-function can be represented either as a generating function of all unitary-matrix integrals or as a Kontsevich-Penner model with potential 1/X (instead of X³ in the cubic Kontsevich model).

We construct a Dark Matter (DM) annihilation module that can encompass the predictions from a wide array of models built to explain the recently reported PAMELA and ATIC/PPB-BETS excesses. We present a detailed analysis of the injection spectrums for DM annihilation and quantitatively demonstrate effects that have previously not been included from the particle physics perspective. With this module we demonstrate the parameter space that can account for the aforementioned excesses and be compatible with existing high energy gamma ray and neutrino experiments. However, we find that it is relatively generic to have some tension between the results of the HESS experiment and the ATIC/PPB-BETS experiments within the context of annihilating DM. We discuss ways to alleviate this tension and how upcoming experiments will be able to differentiate amongst the various possible explanations of the purported excesses.

We study the fermionic T-duality symmetry of integrable Green-Schwarz sigma models on AdS backgrounds. We show that the sigma model on AdS₅ × S¹ background is self-dual under fermionic T-duality. We also construct new integrable sigma models on AdS₂ × CPⁿ. These backgrounds could be realized as supercosets of SU supergroups for arbitrary n, but could also be realized as supercosets of OSp supergroups for n = 1,3. We find that the supercosets based on SU supergroups are self-dual under fermionic T-duality, while the supercosets based on OSp supergroups are not. However, the reasons of OSp supercosets being not self-dual under fermionic T-duality are different. For OSp(6|2) case, corresponding to AdS₂ × CP³ background, the failure is due to the singular fermionic quadratic terms, just like AdS₄ × CP³ case. For OSp(3|2) case, the failure is due to the shortage of right number of κ-symmetry to gauge away the fermionic degrees of freedom, even though the fermionic quadratic term is not singular any more. More general, for the supercosets of the OSp supergroups with superalgebra B(n,m), including AdS₂ × S²ⁿ and AdS₄ × S²ⁿ backgrounds, the sigma models are not self-dual under fermionic T-duality as well, obstructed by the κ-symmetry.

We prove that there are only finitely many distinct semi-simple gauge groups and matter representations possible in consistent 6D chiral (1,0) supergravity theories with one tensor multiplet. The proof relies only on features of the low-energy theory; the consistency conditions we impose are that anomalies should be cancelled by the Green-Schwarz mechanism, and that the kinetic terms for all fields should be positive in some region of moduli space. This result does not apply to the case of the non-chiral (1,1) supergravities, which are not constrained by anomaly cancellation.

Our recent construction arXiv:0903.3966 for the fuzzy 2-sphere in terms of bifundamentals, discovered in the context of the ABJM model, is shown to be explicitly equivalent to the usual (adjoint) fuzzy sphere construction. The matrices ^α that define it play the role of fuzzy Killing spinors on the 2-sphere, out of which all spherical harmonics are constructed. Starting from the quadratic fluctuation action around these solutions in the mass-deformed ABJM theory, we recover a supersymmetric D4-brane action wrapping a 2-sphere, including fermions. We obtain both the usual D4 action with an unusual x-dependence on the sphere, as well as a twisted version in terms of the usual x-dependence, and contrast our result with the Maldacena-Núñez case of a D5 wrapping an S². The twisted and unwisted fields are related by the same matrix ^α.

We analyze flavor-changing-neutral-current (FCNC) effects in the b → s transitions that are induced by family non-universal U(1)' gauge symmetries. After systematically developing the necessary formalism, we present a correlated analysis for the ΔB = 1,2 processes. We adopt a model-independent approach in which we only require family-universal charges for the first and second generations and small fermion mixing angles. We analyze the constraints on the resulting parameter space from B_s−_s mixing and the time-dependent CP asymmetries of the penguin-dominated B_d → (π,ϕ,η',ρ,ω,f₀)K_S decays. Our results indicate that the currently observed discrepancies in some of these modes with respect to the Standard Model predictions can be consistently accommodated within this general class of models.

We describe a number of striking features of a class of smooth solitons in gauged and ungauged minimal supergravity in five dimensions. The solitons are globally asymptotically flat or asymptotically AdS without any Kaluza-Klein directions but contain a minimal sphere formed when a cycle pinches off in the interior of the spacetime. The solutions carry a local magnetic charge and many have rather unusual ergosurfaces. Perhaps most strikingly, many of the solitons have more electric charge or, in the asymptotically AdS case, more electric charge and angular momentum than is allowed by the usual BPS bound. We comment on, but do not resolve, the new puzzle this raises for AdS/CFT.

We construct background-independent Noether charges in Topologically Massive Gravity with negative cosmological constant using its first-order formulation. The procedure is carried out by keeping track of the surface terms in the variation of the action, regardless the value of the gravitational Chern-Simons coupling μ. In particular, this method provides a definition of conserved quantities for solutions at the chiral point μℓ = 1 (ℓ is the AdS radius) that contain logarithmic terms (Log Gravity). It is also shown that the charge formula gives a finite result for warped AdS black holes without the need for any background-substraction procedure.

We examine five-dimensional = 2 gauged supergravity including terms up to four derivatives. These additional terms correspond to the supersymmetric completion of R², and were originally obtained in hep-th/0611329 using conformal supergravity techniques. Here we integrate out the auxiliary fields and obtain the on-shell action for minimal supergravity with such corrections. We then construct R-charged AdS black holes to linear order in the four derivative terms and investigate the effect of these corrections on their thermodynamical properties. Finally, we relate the geometrical coefficients governing the four-derivative corrections to gauge theory data using holographic anomaly matching. This enables us to obtain a microscopic expression for the entropy of the solutions.

We present an orthogonal basis of gauge invariant operators constructed from some complex matrices for the free matrix field, where operators are expressed with the help of Brauer algebra. This is a generalisation of our previous work for a signle complex matrix. We also discuss the matrix quantum mechanics relevant to = 4 SYM on S³ × R. A commuting set of conserved operators whose eigenstates are given by the orthogonal basis is shown by using enhanced symmetries at zero coupling.

This work is the result of the ideas developed by Ken Yoshida about the possibility of extending the range of applications of the matrix model approach to the computation of the holomorphic superpotential of the β-deformed = 4 super Yang-Mills theory both in the presence of a mass term and in the massless limit. Our formulae, while agreeing with all the existing results we can compare with, are valid also in the case of spontaneously broken gauge symmetry.

We consider noncommutative GUT inspired field theories formulated within the enveloping-algebra formalism for anomaly safe compact simple gauge groups. Our theories have only gauge fields and fermions, and we compute the UV divergent part of the one-loop background-field effective action involving two fermionic fields at first order in the noncommutativity parameter θ. We show that, if the second-degree Casimir has the same value for all the irreducible group representations furnished by the fermionic multiplets of the model, then, that UV divergent part can be renormalised by carrying out multiplicative renormalisations of the coupling constant, θ and the fields, along with the inclusion of θ-dependent counterterms which vanish upon imposing the equations of motion. These θ-dependent counterterms have no physical effect since they vanish on-shell. This result along with the vanishing of the UV divergent part of the fermionic four-point functions leads to the unexpected conclusion that the one-loop matter sector of the background-field effective action of these theories is one-loop multiplicatively renormalisable on-shell. We also show that the background-field effective action of the gauge sector of the theories considered here receives no θ-dependent UV divergent contributions at one-loop. We thus conclude that these theories are on-shell one-loop multiplicatively renormalisable at first order in θ.

We consider the resummation of soft gluon emission for squark and gluino hadroproduction at next-to-leading-logarithmic (NLL) accuracy in the framework of the minimal supersymmetric standard model. We present analytical results for squark-squark and squark-gluino production and provide numerical predictions for all squark and gluino pair-production processes at the Tevatron and at the LHC. The size of the soft-gluon corrections and the reduction in the scale uncertainty are most significant for processes involving gluino production. At the LHC, where the sensitivity to squark and gluino masses ranges up to 3 TeV, the corrections due to NLL resummation over and above the NLO predictions can be as high as 35% in the case of gluino-pair production, whereas at the Tevatron, the NLL corrections are close to 40% for squark-gluino final states with sparticle masses around 500 GeV.

We use the conservation of the renormalized boundary stress-energy tensor to obtain the equilibrium condition for a general (thin or fat) black ring solution. We also investigate the role of the spatial stress in the thermodynamics of deformation within the quasilocal formalism of Brown and York and discuss the relation with other methods. In particular, we discuss the quantum statistical relation for the unbalanced black ring solution.

We present new M2 and M5-brane solutions in M-theory based on transverse Gibbons-Hawking spaces. These solutions provide realizations of fully localized type IIA D2/D6 and NS5/D6 brane intersections. One novel feature of these solutions is that the metric functions depend on more than two transverse coordinates (unlike all the other previous known solutions). All the solutions have eight preserved supersymmetries and the world-volume theories of the NS5-branes are new non-local, non-gravitational, six dimensional, T-dual little string theories with eight supersymmetries. We discuss the limits in which the dynamics of the D2 and NS5-branes decouple from the bulk for these solutions.

Based on prototypical example of Al. Zamolodchikov's recursion relations for the four point conformal block and using recently proposed Alday-Gaiotto-Tachikawa (AGT) conjecture, recursion relations are derived for the generalized prepotential of = 2 SYM with f = 0,1,2,3,4 (anti) fundamental or an adjoint hypermultiplets. In all cases the large expectation value limit is derived explicitly. A precise relationship between generic 1-point conformal block on torus and specific 4-point conformal block on sphere is established. In view of AGT conjecture this translates into a relation between partition functions with an adjoint and 4 fundamental hypermultiplets.

We analyze the asymptotic symmetries of near extremal Kerr black holes in four dimensions using the AdS₂/CFT₁ correspondence. We find a Virasoro algebra with central charge c_R = 12J that is independent from the Virasoro algebra (with the same central charge) that acts on the degenerate ground state. The energy of the excitations is computed as well, and we can use Cardy's formula to determine the near extremal entropy. Our result is consistent with the Bekenstein-Hawking area law for near extremal Kerr black holes.

We investigate hard radiation emission in small-angle transplanckian scattering. We show how to reduce this problem to a quantum field theory computation in a classical background (gravitational shock wave). In momentum space, the formalism is similar to the flat-space light cone perturbation theory, with shock wave crossing vertices added. In the impact parameter representation, the radiating particle splits into a multi-particle virtual state, whose wavefunction is then multiplied by individual eikonal factors. As a phenomenological application, we study QCD radiation in transplanckian collisions of TeV-scale gravity models. We derive the distribution of initial state radiation gluons, and find a suppression at large transverse momenta with respect to the standard QCD result. This is due to rescattering events, in which the quark and the emitted gluon scatter coherently. Interestingly, the suppression factor depends on the number of extra dimensions and provides a new experimental handle to measure this number. We evaluate the leading-log corrections to partonic cross-sections due to the initial state radiation, and prove that they can be absorbed into the hadronic PDF. The factorization scale should then be chosen in agreement with an earlier proposal of Emparan, Masip, and Rattazzi. In the future, our methods can be applied to the gravitational radiation in transplanckian scattering, where they can go beyond the existing approaches limited to the soft radiation case.

We compute the one-loop amplitude for a Higgs boson, a quark-antiquark pair and a pair of gluons of negative helicity, i.e. for the next-to-maximally helicity violating (NMHV) case, (H,1⁻,2_q⁺,3_g⁻,4_g⁻). The calculation is performed using an effective Lagrangian which is valid in the limit of very large top quark mass. As a result of this paper all amplitudes for the transition of a Higgs boson into 4 partons are now known analytically at one-loop order.

In the Type II superstring the 4-point function for massless NS-NS bosons at one-loop is well known [1, 14]. The overall constant factor in this amplitude is very important because it needs to satisfy the unitarity and S-duality conditions [14]. This coefficient has not been computed in the pure spinor formalism due to the difficulty to solve the integrals on the pure spinors space. In this paper we compute it by using the non-minimal pure spinor formalism and we will show that the answer is in perfect agreement with the one given in [14].

We consider a model of static cosmic string loops in type IIB string theory, where the strings wrap cycles within the internal space. The strings are not topologically stabilised, however the presence of a lifting potential traps the windings giving rise to kinky cycloops. We find that PBH formation occurs at early times in a small window, whilst at late times we observe the formation of dark matter relics in the scaling regime. This is in stark contrast to previous predictions based on field theoretic models. We also consider the PBH contribution to the mass density of the universe, and use the experimental data to impose bounds on the string theory parameters.

We show how the link variables of Arkani-Hamed, Cachazo, Cheung and Kaplan (ACCK), can be used to compute general gluon tree amplitudes in the twistor string. They arise from instanton sectors labelled by d, with d = n−1, where n is the number of negative helicities. Read backwards, this shows how the various forms for the tree amplitudes studied by ACCK can be grouped into contour integrals whose structure implies the existence of an underlying string theory.

We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain ``messenger mesons," which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.

The Standard Model (SM) predictions for the lepton flavor-violating (LFV) processes like μ → eγ are well far from any realistic experimental resolution, thus, the appearance of μ → eγ at the running MEG experiment would unambiguously point towards a New Physics (NP) signal. In this article, we discuss the phenomenological implications in case of observation/improved upper bound on μ → eγ at the running MEG experiment for supersymmetric (SUSY) scenarios with a see-saw mechanism accounting for the neutrino masses. We outline the role of related observables to μ → eγ in shedding light on the nature of the SUSY LFV sources providing useful tools i) to reconstruct some fundamental parameters of the neutrino physics and ii) to test whether an underlying SUSY Grand Unified Theory (GUT) is at work. The perspectives for the detection of LFV signals in τ decays are also discussed.

We analyze the role played by anomaly poles in an anomalous gauge theory by discussing their signature in the corresponding off-shell effective action. The origin of these contributions, in the most general kinematical case, is elucidated by performing a complete analysis of the anomaly vertex at perturbative level. We use two independent (but equivalent) representations: the Rosenberg representation and the longitudinal/transverse (L/T) parameterization, used in recent studies of g−2 of the muon and in the proof of non-renormalization theorems of the anomaly vertex. The poles extracted from the L/T parameterization do not couple in the infrared for generic anomalous vertices, as in Rosenberg, but we show that they are responsible for the violations of unitarity in the UV region, using a class of pole-dominated amplitudes. We conclude that consistent formulations of anomalous models require necessarily the cancellation of these polar contributions. Establishing the UV significance of these terms provides a natural bridge between the anomalous effective action and its completion by a nonlocal theory. Some additional difficulties with unitarity of the mechanism of inflow in extra dimensional models with an anomalous theory on the brane, due to the presence of anomaly poles, are also pointed out.

It is well known that a constant O(n,n,) transformation can relate different string backgrounds with ncommuting isometries that have very different geometric and topological properties. Here we construct discrete families of (flux) backgrounds on internal manifolds of different topologies by performing certain coordinate dependent O(d,d) transformations, where d is the dimension of the internal manifold. Our two principal examples include respectively the family of type IIB compactifications with D5 branes and O5 planes on six-dimensional nilmanifolds, and the heterotic torsional backgrounds.

Based on a recent idea by Krohn and Yavin, we construct a little Higgs model with an internal parity that is not broken by anomalous Wess-Zumino-Witten terms. The model is a modification of the ``minimal moose'' models by Arkani-Hamed et al. and Cheng and Low. The new parity prevents large corrections to oblique electroweak parameters and leads to a viable dark matter candidate. It is shown how the complete Standard Model particle content, including quarks and leptons together with their Yukawa couplings, can be implemented. Successful electroweak symmetry breaking and consistency with electroweak precision constraints is achieved for natural parameters choices. A rich spectrum of new particles is predicted at the TeV scale, some of which have sizable production cross sections and striking decay signatures at the LHC.

For supersymmetric theories with gravitino dark matter, the maximal reheating temperature consistent with big bang nucleosynthesis bounds arises when the physical gaugino masses are degenerate. We consider the cases of a stau or sneutrino next-to-lightest superpartner, which have relatively less constraint from big bang nucleosynthesis. The resulting parameter space is consistent with leptogenesis requirements, and can be reached in generalized gauge mediation models. Such models illustrate a class of theories that overcome the well-known tension between big bang nucleosynthesis and leptogenesis.

We investigate the role of boundary conditions in gauge theories in AdS₄. The presence of the boundary can break the gauge symmetry consistently with AdS₄ isometries. We show that, as a consequence, the gauge bosons associated to the broken symmetries become massive at one loop. In particular chiral gauge theories such us the Standard Model are necessarily massive in AdS₄. We briefly discuss similarities with the Schwinger model and implications for CFTs in three dimensions.

We show how Newtonian gravity emerges on 4-dimensional non-commutative spacetime branes in Yang-Mills matrix models. Large matter clusters such as galaxies are embedded in large-scale harmonic deformations of the space-time brane, which screen gravity for long distances. On shorter scales, the local matter distribution reproduces Newtonian gravity via local deformations of the brane and its metric. The harmonic ``gravity bag'' acts as a halo with effective positive energy density. This leads in particular to a significant enhancement of the orbital velocities around galaxies at large distances compared with the Newtonian case, before dropping to zero as the geometry merges with a Milne-like cosmology. Besides these ``harmonic'' solutions, there is another class of solutions which is more similar to Einstein gravity. Thus the IKKT model provides an accessible candidate for a quantum theory of gravity.

We consider the high-energy limit of the colour-ordered one-loop five-gluon amplitude in the planar maximally supersymmetric = 4 Yang-Mills theory in multi-Regge kinematics where all of the gluons are strongly ordered in rapidity. We apply the calculation of the one-loop pentagon in D = 6−2 performed in a companion paper [1] to compute the one-loop five-gluon amplitude through to (²). Using the factorisation properties of the amplitude in the high-energy limit, we extract the one-loop gluon-production vertex to the same accuracy, and, by exploiting the iterative structure of the gluon-production vertex implied by the BDS ansatz, we perform the first computation of the two-loop gluon-production vertex up to and including finite terms.

We provide the first theoretical study of a novel variable, a_T, proposed in ref. [1] as a more accurate probe of the region of low transverse momentum p_T, for the Z boson p_Tdistribution at hadron colliders. The a_T is the component ofp_T transverse to a suitably defined axis. Our study involves resummation of large logarithms in a_T up to the next-to-leading logarithmic accuracy and we compare the results to those for the well-known p_T distribution, identifying important physical differences between the two cases. We also test our resummed result at the two-loop level by comparing its expansion to order α_s² with the corresponding fixed-order results and find agreement with our expectations.

We discuss twistor-like interpretation of the Sp(8) invariant formulation of 4d massless fields in ten dimensional Lagrangian Grassmannian Sp(8)/P which is the generalized space-time in this framework. The correspondence space C isSpH(8)/PH where SpH(8) is the semidirect product of Sp(8) with Heisenberg group SpH_M and PH is some quasiparabolic subgroup of SpH(8). Spaces of functions on Sp(8)/P and SpH(8)/PH consist of Q_P closed functions on Sp(8) and Q_PH closed functions on SpH(8), where Q_P and Q_PH are canonical BRST operators of P and PH. The space of functions on the generalized twistor space T identifies with the SpH(8) Fock module. Although T cannot be realized as a homogeneous space, we find a nonstandard SpH(8) invariant BRST operator Q (Q² = 0) that gives rise to an appropriate class of functions via the condition Qf = 0 equivalent to the unfolded higher-spin equations. The proposed construction is manifestly Sp(8) invariant, globally defined and coordinate independent. Its Minkowski analogue gives a version of twistor theory with both types of chiral spinors treated on equal footing. The extensions to the higher rank case with several Heisenberg groups and to the complex case are considered. A relation with Riemann theta functions, that are Q-closed, is discussed.

We propose a realistic β-Beam experiment with four source ions and two baselines for the best possible sensitivity to θ₁₃, CP violation and mass hierarchy. Neutrinos from ¹⁸Ne and ⁶He with Lorentz boost γ = 350 are detected in a 500 kton water Čerenkov detector at a distance L = 650 km (first oscillation peak) from the source. Neutrinos from ⁸B and ⁸Li are detected in a 50 kton magnetized iron detector at a distance L = 7000 km (magic baseline) from the source. Since the decay ring requires a tilt angle ϑ = 34.5° to send the beam to the magic baseline, the far end of the ring has a maximum depth of d = 2132 m for magnetic field strength of 8.3 T, if one demands that the fraction of ions that decay along the straight sections of the racetrack geometry decay ring (called livetime) is 0.3. We alleviate this problem by proposing to trade reduction of the livetime of the decay ring with the increase in the boost factor of the ions, such that the number of events at the detector remains almost the same. This allows to substantially reduce the maximum depth of the decay ring at the far end, without significantly compromising the sensitivity of the experiment to the oscillation parameters. We take ⁸B and ⁸Li with γ = 390 and 656 respectively, as these are the largest possible boost factors possible with the envisaged upgrades of the SPS at CERN. This allows us to reduce d of the decay ring by a factor of 1.7 for 8.3 T magnetic field. Increase of magnetic field to 15 T would further reduce d to 738 m only. We study the sensitivity reach of this two baseline two storage ring β-Beam experiment, and compare it with the corresponding reach of the other proposed facilities. We find that for values of sin² 2θ₁₃>10⁻³ this β-Beam setup outperforms the Neutrino Factory sensitivities.

We study a statistical model defined by a conformally invariant distribution of overlapping spheres in arbitrary dimension d. The model arises as the asymptotic distribution of cosmic bubbles in d+1 dimensional de Sitter space, and also as the asymptotic distribution of bubble collisions with the domain wall of a fiducial ``observation bubble'' in d+2 dimensional de Sitter space. In this note we calculate the 2-, 3-, and 4-point correlation functions of exponentials of the ``bubble number operator'' analytically in d = 2. We find that these correlators are free of infrared divergences, covariant under the global conformal group, charge conserving, and transform with positive conformal dimensions that are related in a novel way to the charge. Although by themselves these operators probably do not define a full-fledged conformal field theory, one can use the partition function on a sphere to compute an approximate central charge in the 2D case. The theory in any dimension has a noninteracting limit when the nucleation rate of the bubbles in the bulk is very large. The theory in two dimensions is related to some models of continuum percolation, but it is conformal for all values of the tunneling rate.

We study local operators of U(N) × U(N) = 6 Chern-Simons-matter theory including a class of magnetic monopole operators. To take into account the interaction of monopoles and basic fields for large Chern-Simons level k, we consider the appropriate perturbation theory in 1/k which reliably describes small excitations around protected chiral operators. We also compute the superconformal index with some simple monopole operators and show that it agrees with the recent result obtained from localization. For this agreement, it is crucial that excitations of gauge fields and some matter scalars mix, which is described classically by odd dimensional self-duality like equations.

We construct three-dimensional = 2 Chern-Simons-quiver theories which are holographically dual to the M-theory Freund-Rubin solutions AdS₄ × V_5,2/_k (with or without torsion G-flux), where V_5,2 is a homogeneous Sasaki-Einstein seven-manifold. The global symmetry group of these theories is generically SU(2) × U(1) × U(1)_R, and they are hence non-toric. The field theories may be thought of as the n = 2 member of a family of models, labelled by a positive integer n, arising on multiple M2-branes at certain hypersurface singularities. We describe how these models can be engineered via generalized Hanany-Witten brane constructions. The AdS₄ × V_5,2/_k solutions may be deformed to a warped geometry ^1,2 × T*S⁴/_k, with self-dual G-flux through the four-sphere. We show that this solution is dual to a supersymmetric mass deformation, which precisely modifies the classical moduli space of the field theory to the deformed geometry.

Recently Aharony, Bergman and Jafferis (ABJ) have argued that a 3d U(N+M)_k × U(N)_−k Chern-Simons gauge theory may have a vacuum with = 6 supersymmetry only if M⩽k and if a certain period of the B-field in a IIA background is quantized. We use a braneology argument to argue that = 3 supersymmetry may be preserved under the weaker condition that 2Nk⩾M(M−k) with no restriction on the B-field. IIB brane cartoons and 11d supergravity solutions corresponding to = 3 vacua that do not preserve = 6 supersymmetry are argued to represent cascading gauge theories, generalizing the = 2 Seiberg duality conjectured by Giveon and Kutasov. While as usual the M2-brane charge runs as a result of the twisted Bianchi identity for *G₄, the M5-brane charge running relies on the fact that it wraps a torsion homology cycle.

We study cold fermionic atoms using the holographic principle. We note that current atomic experiments with massive fermions trapped in a harmonic potential in the unitarity limit behave as massless fermions thanks to the Thomas-Fermi approximation. We map the thermodynamics of strongly correlated massless fermion to that of the charged black hole and study the thermodynamics and transport properties of cold fermions at strong coupling at finite temperature and density. In cold limit, the specific heat of charged black hole is linear in T independent of the dimensionality, which is reminiscent of Fermi liquids. The shear viscosity per particle is shown to be finite as a consequence of the non-vanishing of the entropy. We show that our holographic results compare favorably with most of the current atomic data.

Recently, Wilson loops with the shape of a double helix have played an important role in studying large spin operators in gauge theories. They correspond to a quark and an anti-quark moving in circles on an S³ (and therefore each of them describes a helix in R × S³). In this paper we consider the case where the particles have two angular momenta on the S³. The string solution corresponding to such Wilson loop can be found using the relation to the Neumann-Rosochatius system allowing the computation of the energy and angular momenta of the configuration. The particular case of only one angular momentum is also considered. It can be thought as an analytic continuation of the rotating strings which are dual to operators in the SL(2) sector of = 4 SYM.

In the landscape, if there is to be any prospect of scientific prediction, it is crucial that there be states which are distinguished in some way. The obvious candidates are states which exhibit symmetries. Here we focus on states which exhibit discrete symmetries. Such states are rare, but one can speculate that they are cosmological attractors. We investigate the problem in model landscapes and cosmologies which capture some of the features of candidate flux landscapes. In non-supersymmetric theories we find no evidence that such states might be cosmologically favored. In supersymmetric theories, simple arguments suggest that states which exhibit R symmetries might be. Our considerations lead us to raise questions about some popular models of eternal inflation.

We calculate the full (α_s²α) corrections to the process of gluino pair production at hadron colliders in the framework of the real MSSM. We show that these contributions can be neglected at the LHC performing a scan over a wide region of the parameter space. The impact of these corrections in the parameter range investigated at the Tevatron is small.

We study QCD-like four dimensional theories in the theoretically controlled framework of deformation theory and/or twisted partition function on S¹ × ³. By using duality, we show that a class of one-flavor theories exhibit new physical phenomena: discrete chiral symmetry breaking (χSB) induced by the condensation of topological disorder operators, and confinement and the generation of mass gap due to new non-selfdual topological excitations. In the ⁴ limit, we argue that the mass gap disappears, the χSB vacua are of runaway type, and the theory flows to a CFT. We also study mixed-representation theories and find abelian χSB by topological operators charged under abelian chiral symmetries. These are reminiscent to, but distinct, from Seiberg-Witten theory with matter, where 4d monopoles have non-abelian chiral charge. This examination also helps us refine our recent bounds on the conformal window. In an appendix, we also discuss mixed vectorlike/chiral representation theories, obtain bounds on their conformal windows, and compare with the all-order beta function results of arXiv:0911.0931.

We study light-cone gauge string field theory in noncritical space-time dimensions. Such a theory corresponds to a string theory in a Lorentz noninvariant background. We identify the worldsheet theory for the longitudinal coordinate variables X^± and study its properties. It is a CFT with the right value of Virasoro central charge, using which we propose a BRST invariant formulation of the worldsheet theory.

We study the formation of marginally trapped surfaces in the head-on collision of two shock waves in de Sitter space-time as a function of the cosmological constant and the shock wave energy. We search for a marginally trapped surface on the past light cone of the collision plane. For space-time dimensions D ⩾ 3, there exists a critical value of the shock wave energy above which there is no trapped surface of this type. For D>3, the critical value of the shock wave energy depends on the de Sitter radius, and there is no this type trapped surface formation for a large cosmological constant. For D = 3, the critical value of the shock wave energy is independent of the cosmological constant. At the critical point, the trapped surface is finite. Below the critical energy value, the area of the trapped surface depends on the cosmological constant and the shock wave energy.

Presented in this paper the nature of the supersymmetrical representation theory behind 4D, = 1 theories, as described by component fields, is investigated using the tools of Adinkras and Garden Algebras. A survey of familiar matter multiplets using these techniques reveals they are described by two fundamental valise Adinkras that are given the names of the cis-Valise (c-V) and the trans-Valise (t-V). A conjecture is made that all off-shell 4D, = 1 component descriptions of supermultiplets are associated with two integers (n_c, n_t) — the numbers of c-V and t-V Adinkras that occur in the representation.

The J/ψ decay angular distributions have been measured in inelastic photoproduction in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb⁻¹. The range in photon-proton centre-of-mass energy, W, was 50 < W < 180 GeV. The J/ψ mesons were identified through their decay into muon pairs. The polar and azimuthal angles of the μ⁺ were measured in the J/ψ rest frame and compared to theoretical predictions at leading and next-to-leading order in QCD.

We find new supergravity solutions generated by D5-branes wrapping a four-cycle and preserving four and two supersymmetries. We first consider the configuration in which the fivebranes wrap a four-cycle in a Calabi-Yau threefold, which preserves four supersymmetries and is a gravity dual to the Coulomb branch of two-dimensional gauge theories with = (2,2) supersymmetry. We also study the case of fivebranes wrapping a co-associative four-cycle in a manifold of G₂-holonomy, which provides a gravity dual of = (1,1) supersymmetric Yang-Mills theory in two dimensions. We also discuss the addition of unquenched fundamental matter fields to these backgrounds and find the corresponding gravity solutions with flavor brane sources.

We compute the 2-loop thermal partition function of Yang-Mills theory on a small 3-sphere, in the large N limit with weak 't Hooft coupling λ = g_YM²N. We include N_s scalars and N_f chiral fermions in the adjoint representation of the gauge group (S)U(N), with arbitrary Yukawa and quartic scalar couplings, assuming only commutator interactions. From this computation one can extract information on the perturbative corrections to the spectrum of the theory, and the correction to its Hagedorn temperature. Furthermore, the computation of the 2-loop partition function is a necessary step towards determining the order of the deconfinement phase transition at weak coupling, for which a 3-loop computation is needed.

We study and construct non-abelian hermitian Yang-Mills (HYM) instantons on Calabi-Yau cones. By means of a particular isometry preserving ansatz, the HYM equations are reduced to a novel Higgs-Yang-Mills flow on the Einstein-Kähler base. For any 2d-dimensional Calabi-Yau cone, we find explicit solutions of the flow equations that correspond to non-trivial SU(d) HYM instantons. These can be regarded as deformations of the spin connection of the Calabi-Yau cone.

J. Harer and D. Zagier have found a strikingly simple generating function [1,2] for exact (all-genera) 1-point correlators in the Gaussian Hermitian matrix model. In this paper we generalize their result to 2-point correlators, using Toda integrability of the model. Remarkably, this exact 2-point correlation function turns out to be an elementary function — arctangent. Relation to the standard 2-point resolvents is pointed out. Some attempts of generalization to 3-point and higher functions are described.

The simplest partition function, associated with homogeneous symmetric forms S of degree r in n variables, is integral discriminant J_n|r(S) = ∫e^{−S(x₁,...,x_n)}dx₁...dx_n. Actually, S-dependence remains the same if e^−S in the integrand is substituted by arbitrary function f(S), i.e. integral discriminant is a characteristic of the form S itself, and not of the averaging procedure. The aim of the present paper is to calculate J_n|r in a number of non-Gaussian cases. Using Ward identities — linear differential equations, satisfied by integral discriminants — we calculate J_2|3,J_2|4,J_2|5 and J_3|3. In all these examples, integral discriminant appears to be a generalized hypergeometric function. It depends on several SL(n) invariants of S, with essential singularities controlled by the ordinary algebraic discriminant of S.

We investigate the phenomenology of general gauge mediation in the MSSM. We apply the strict definition of gauge mediated SUSY-breaking where B_μ is generated only through gauge interactions, and as a result is very close to zero at the messenger scale. In this setup tan β is a prediction rather than an input. The input parameters are independent scales for the gaugino masses, the scalar masses and the messenger mass in accord with general gauge mediation. We investigate the spectra, the constraints on the parameter space from direct searches and indirect observables, as well as fine-tuning. The favoured region of parameter space includes and interpolates between non-split and mildly split SUSY, characteristic of ordinary gauge mediation and direct gauge mediation models, respectively.