One-loop W L W L and Z L Z L scattering from the electroweak Chiral Lagrangian with a light Higgs-like scalar

By including the recently discovered Higgs-like scalar φ in the Electroweak Chiral Lagrangian, and using the Equivalence Theorem, we carry out the complete one-loop computation of the elastic scattering amplitude for the longitudinal components of the gauge bosons V = W , Z at high energy. We also compute φφ → φφ and the inelastic process VV → φφ , and identify the counterterms needed to cancel the divergences, namely the well known a 4 and a 5 chiral parameters plus three additional ones only superficially treated in the literature because of their dimension 8. Finally we compute all the partial waves and discuss the limitations of the one-loop computation due to only approximate unitarity

Yang–Mills theory for semidirect products G⋉g∗ and its instantons

Yang–Mills theory with a symmetry algebra that is the semidirect product h⋉h∗ defined by the coadjoint action of a Lie algebra h on its dual h∗ is studied. The gauge group is the semidirect product Gh⋉h∗ , a noncompact group given by the coadjoint action on h∗ of the Lie group Gh of h . For h simple, a method to construct the self–antiself dual instantons of the theory and their gauge nonequivalent deformations is presented. Every Gh⋉h∗ instanton has an embedded Gh instanton with the same instanton charge, in terms of which the construction is realized. As an example, h=su(2) and instanton charge one is considered. The gauge group is in this case SU(2)⋉R3 . Explicit expressions for the selfdual connection, the zero modes and the metric and complex structures of the moduli space are given

Higgs-otic inflation and string theory

We propose that inflation is driven by a (complex) neutral Higgs of the MSSM extension of the SM, in a chaotic-like inflation setting. The SUSY breaking soft term masses are of order 10 12 − 10 13 GeV, which is identified with the inflaton mass scale and is just enough to stabilise the SM Higgs potential. The fine-tuned SM Higgs has then a mass around 126 GeV, in agreement with LHC results. We point out that the required large field excursions of chaotic inflation may be realised in string theory with the (complex) inflaton/Higgs identified with a continuous Wilson line or D-brane position. We show specific examples and study in detail a IIB orientifold with D7-branes at singularities, with SM gauge group and MSSM Higgs sector. In this case the inflaton/Higgs fields correspond to D7-brane positions along a two-torus transverse to them. Masses and monodromy are induced by closed string G 3 fluxes, and the inflaton potential can be computed directly from the DBI+CS action. We show how this action sums over Planck suppressed corrections, which amount to a field dependent rescaling of the inflaton fields, leading to a linear potential in the large field regime. We study the evolution of the two components of the Higgs/inflaton and compute the slow-roll parameters for purely adiabatic perturbations. For large regions of initial conditions slow roll inflation occurs and 50-60 efolds are obtained with r > 0.07, testable in forthcoming experiments. Our scheme is economical in the sense that both EWSB and inflation originate in the same sector of the theory, all inflaton couplings are known and reheating occurs efficiently

Transplanckian axions!?

We discuss quantum gravitational effects in Einstein theory coupled to periodic axion scalars to analyze the viability of several proposals to achieve superplanckian axion periods (aka decay constants) and their possible application to large field inflation models. The effects we study correspond to the nucleation of euclidean gravitational instantons charged under the axion, and our results are essentially compatible with (but independent of) the Weak Gravity Conjecture, as follows: single axion theories with superplanckian periods contain gravitational instantons inducing sizable higher harmonics in the axion potential, which spoil superplanckian inflaton field range. A similar result holds for multi-axion models with lattice alignment (like the Kim-Nilles-Peloso model). Finally, theories with N axions can still achieve a moderately superplanckian periodicity (by a N $$\sqrt{N}$$ factor) with no higher harmonics in the axion potential. The Weak Gravity Conjecture fails to hold in this case due to the absence of some instantons, which are forbidden by a discrete Z N gauge symmetry. Finally we discuss the realization of these instantons as euclidean D-branes in string compactifications

Anomalous transport in holographic chiral superfluids via Kubo formulae

We study anomalous conductivities in Chiral Superfluids in the framework of two different holographic models, by means of Kubo formulae. In addition, we point out the existence of an anomalous transport phenomenon that consists in the presence of a charge density when the superfluid velocity is aligned with a magnetic field. It has been pointed out recently that certain chiral conductivities in holographic superfluids exhibit universal behavior at zero temperature. We show that anomalous conductivities always stabilize at low temperatures in our setup. Even though the particular value they acquire is model-dependent, it seems to be robust and determined solely by the interplay between the broken symmetries and the anomalies

Dispersive calculation of complex Regge trajectories for the lightest f2 resonances and the K⁎(892)

We apply a recently developed dispersive formalism to calculate the Regge trajectories of the f2(1270) , f2′(1525) and K⁎(892) mesons. Trajectories are calculated, not fitted to a family of resonances. Assuming that these resonances can be treated in the elastic approximation, the only input are the pole position and residue of a resonance. In all three cases, the predicted Regge trajectories are almost real and linear, with slopes in agreement with the universal value of order 1 GeV −2 . We also show how these results barely change when considering more than two subtractions in the dispersive formalism

Antisymmetric tensor Z p gauge symmetries in field theory and string theory

We consider discrete gauge symmetries in D dimensions arising as remnants of broken continuous gauge symmetries carried by general antisymmetric tensor fields, rather than by standard 1-forms. The lagrangian for such a general Z p gauge theory can be described in terms of a r -form gauge field made massive by a ( r  − 1)-form, or other dual realizations, that we also discuss. The theory contains charged topological defects of different dimensionalities, generalizing the familiar charged particles and strings in D  = 4. We describe realizations in string theory compactifications with torsion cycles, or with background field strength fluxes. We also provide examples of non-abelian discrete groups, for which the group elements are associated with charged objects of different dimensionality

Negative magnetoresistivity in chiral fluids and holography

In four dimensions Weyl fermions possess a chiral anomaly which leads to several special features in the transport phenomena, such as the negative longitudinal magnetoresistivity . In this paper, we study its inverse, the longitudinal magnetoconductivity, in the case of a chiral anomalous system with a background magnetic field B using the linear response method in the hydrodynamic limit and from holography. Our hydrodynamic results show that in general we need to have energy, momentum and charge dissipations to get a finite DC longitudinal magnetoconductivity due to the existence of the chiral anomaly. Applying the formula that we get from hydrodynamics to the holographic system in the probe limit, we find that the result in the hydrodynamic regime matches that calculated from holography via Kubo formula. The holographic result shows that in an intermediate regime of B there is naturally a negative magnetoresistivity which decreases as 1 /B . At small B direct calculations in the holographic system suggest that holography provides a new explanation for the small B positive magnetoresistivity behavior seen in experiment, i.e. the small B behavior comes from the quantum critical conductivity being affected by the chiral anomaly

Topological vertex for Higgsed 5d T N theories

We analyse the computation of the partition function of 5d T N theories in Higgs branches using the topological vertex. The theories are realised by a web of ( p, q ) 5-branes whose dual description may be given by an M-theory compactification on a certain local non-toric Calabi-Yau threefold. We explicitly show how it is possible to directly apply the topological vertex to the non-toric geometry. Using this novel technique, which considerably simplifies the computation by the existing method, we are able to compute the partition function of the higher rank E 6 , E 7 and E 8 theories. Moreover we show how in some specific cases similar results can be extended to the computation of the partition function of 5d T N theories in the Higgs branch using the refined topological vertex. These cases require a modification of the refined topological vertex

The inflaton as an MSSM Higgs and open string modulus monodromy inflation

It has been recently pointed out that high scale inflation, as recently hinted by the BICEP2 results, is consistent with the identification of an inflaton mass mI≃1013 GeV with the SUSY breaking scale in an MSSM with a fine-tuned SM Higgs. This identification leads to a Higgs mass mh≃126 GeV , consistent with LHC measurements. Here we propose that this naturally suggests to identify the inflaton with the heavy MSSM Higgs system. The fact that the extrapolated Higgs coupling λSM≃0 at scales below the Planck scale suggests the Higgs degrees of freedom could be associated with a Wilson line or D-brane position modulus in string theory. The Higgs system then has a shift symmetry and an N=2 structure which guarantees that its potential has an approximate quadratic chaotic inflation form. These moduli in string compactifications, being compact, allow for trans-Planckian inflaton field range analogous to a version of monodromy inflation