Symmetry Of String Theory Research Articles

Mirror Symmetry for New Physics beyond the Standard Model in 4D Spacetime

The two discrete generators of the full Lorentz group O(1,3) in 4D spacetime are typically chosen to be parity inversion symmetry P and time reversal symmetry T, which are responsible for the four topologically separate components of O(1,3). Under general considerations of quantum field theory (QFT) with internal degrees of freedom, mirror symmetry is a natural extension of P, while CP symmetry resembles T in spacetime. In particular, mirror symmetry is critical as it doubles the full Dirac fermion representation in QFT and essentially introduces a new sector of mirror particles. Its close connection to T-duality and Calabi–Yau mirror symmetry in string theory is clarified. Extension beyond the Standard Model can then be constructed using both left- and right-handed heterotic strings guided by mirror symmetry. Many important implications such as supersymmetry, chiral anomalies, topological transitions, Higgs, neutrinos, and dark energy are discussed.

Statistical mirror symmetry

In this paper, we investigate a duality between Hermitian and almost Kähler structures on the tangent manifold TM induced by pairs of conjugate connections on its base, affine Riemannian manifold M. In the context of information geometry, the classical theory of statistical manifold (which we call S-geometry) prescribes a parametrized family of probability distributions with a Fisher-Rao metric g and, using the Amari-Chensov tensor, a family of dualistic, torsion-free connections ∇(α), known as α-connections on M. Here we prescribe an alternative geometric framework (which we call P-geometry or partially flat geometry) by treating such parametrization as affine coordinates with respect to a flat connection ∇, and considering its g-conjugate connection ∇⁎ which is curvature-free but generally carries torsion. Under P-geometry, the triplet (g,∇,∇⁎) on M leads to a pair of complex and almost Kähler structures on TM, in “mirror correspondence” to each other. Such complex-to-symplectic correspondence is reminiscent of mirror symmetry in string theory. We discuss the statistical meaning of mirror correspondence in terms of reference duality and representation duality in (various generalizations of) contrast/divergence functions characterizing proximity of probability distributions within a parametric statistical model.

More on quantum chiral higher spin gravity

Chiral Higher Spin Gravity is unique in being the smallest higher spin extension of gravity and in having a simple local action both in flat and (anti)-de Sitter spaces. It must be a closed subsector of any other higher spin theory in four dimensions, which makes it an important building block and benchmark. Using the flat space version for simplicity, we perform a thorough study of quantum corrections in Chiral Theory, which strengthen our earlier results arXiv:1805.00048. Even though the interactions are naively non-renormalizable, we show that there are no UV-divergences in two-, three- and four-point amplitudes at one loop thanks to the higher spin symmetry. We also give arguments that the AdS Chiral Theory should exhibit similar properties. It is shown that Chiral Theory admits Yang-Mills gaugings with $U(N)$, $SO(N)$ and $USp(N)$ groups, which is reminiscent of the Chan-Paton symmetry in string theory.

Highly symmetric D-brane-anti-D-brane effective actions

The entire S-matrix elements of four, five and six point functions of D-brane-anti D-brane system are explored. To deal with symmetries of string amplitudes as well as their all order α′ corrections we first address a four point function of one closed string Ramond-Ramond (RR) and two real tachyons on the world volume of brane-anti brane system. We then focus on symmetries of string theory as well as universal tachyon expansion to achieve both string and effective field theory of an RR and three tachyons where the complete algebraic analysis for the whole S-matrix < {V}_{C^{-1}}{V}_{T^{-1}}{V}_{T^0}{V}_{T^0}> was also revealed. Lastly, we employ all the conformal field theory techniques to < {V}_{C^{-1}}{V}_{T^{-1}}{V}_{T^0}{V}_{T^0}{V}_{T^0}> , working out with symmetries of theory and find out the expansion for the amplitude to be able to precisely discover all order singularity structures of D-brane-anti-D-brane effective actions of string theory. Various remarks about the so called generalized Veneziano amplitude and new string couplings are elaborated as well.

Symmetry of String Scattering Amplitudes

We explore the hidden symmetry in string theory by studying string scattering amplitudes. We calculate 4-point open string scattering amplitudes with three tachyons and a massive higher spin string state. The result can be expressed as Type D Lauricella functions which are generalization of Gaussian Hypergeometric functions. In various high energy limits, the string amplitudes reduced to the expected results that we obtained previously. We find exact SL (K + 3, ℂ) symmetry for the string amplitudes at general energy.

String theory as a higher spin theory

The symmetries of string theory on ${\rm AdS}_3 \times {\rm S}^3 \times \mathbb{T}^4$ at the dual of the symmetric product orbifold point are described by a so-called Higher Spin Square (HSS). We show that the massive string spectrum in this background organises itself in terms of representations of this HSS, just as the matter in a conventional higher spin theory does so in terms of representations of the higher spin algebra. In particular, the entire untwisted sector of the orbifold can be viewed as the Fock space built out of the multiparticle states of a single representation of the HSS, the so-called `minimal' representation. The states in the twisted sector can be described in terms of tensor products of a novel family of representations that are somewhat larger than the minimal one.

Modular invariant inflation

Modular invariance is a striking symmetry in string theory, which may keep stringy corrections under control. In this paper, we investigate a phenomenological consequence of the modular invariance, assuming that this symmetry is preserved as well as in a four dimensional (4D) low energy effective field theory. As a concrete setup, we consider a modulus field T whose contribution in the 4D effective field theory remains invariant under the modular transformation and study inflation drived by T. The modular invariance restricts a possible form of the scalar potenntial. As a result, large field models of inflation are hardly realized. Meanwhile, a small field model of inflation can be still accomodated in this restricted setup. The scalar potential traced during the slow-roll inflation mimics the hilltop potential Vht, but it also has a non-negligible deviation from Vht. Detecting the primordial gravitational waves predicted in this model is rather challenging. Yet, we argue that it may be still possible to falsify this model by combining the information in the reheating process which can be determined self-completely in this setup.

Formal and physical equivalence in two cases in contemporary quantum physics

The application of analytic continuation in quantum field theory (QFT) is juxtaposed to T-duality and mirror symmetry in string theory. Analytic continuation—a mathematical transformation that takes the time variable t to negative imaginary time—it—was initially used as a mathematical technique for solving perturbative Feynman diagrams, and was subsequently the basis for the Euclidean approaches within mainstream QFT (e.g., Wilsonian renormalization group methods, lattice gauge theories) and the Euclidean field theory program for rigorously constructing non-perturbative models of interacting QFTs. A crucial difference between theories related by duality transformations and those related by analytic continuation is that the former are judged to be physically equivalent while the latter are regarded as physically inequivalent. There are other similarities between the two cases that make comparing and contrasting them a useful exercise for clarifying the type of argument that is needed to support the conclusion that dual theories are physically equivalent. In particular, T-duality and analytic continuation in QFT share the criterion for predictive equivalence that two theories agree on the complete set of expectation values and the mass spectra and the criterion for formal equivalence that there is a “translation manual” between the physically significant algebras of observables and sets of states in the two theories. The analytic continuation case study illustrates how predictive and formal equivalence are compatible with physical inequivalence, but not in the manner of standard underdetermination cases. Arguments for the physical equivalence of dual theories must cite considerations beyond predictive and formal equivalence. The analytic continuation case study is an instance of the strategy of developing a physical theory by extending the formal or mathematical equivalence with another physical theory as far as possible. That this strategy has resulted in developments in pure mathematics as well as theoretical physics is another feature that this case study has in common with dualities in string theory.

The string landscape, black holes and gravity as the weakest force

We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale Lambda=g M_{Pl}, invisible to the low-energy effective field theorist, which sets a cutoff on the validity of the effective theory. Moreover, there is some light charged particle with mass smaller than or equal to Lambda. The bound is motivated by arguments involving holography and absence of remnants, the (in) stability of black holes as well as the non-existence of global symmetries in string theory. A sharp form of the conjecture is that there are always light "elementary" electric and magnetic objects with a mass/charge ratio smaller than the corresponding ratio for macroscopic extremal black holes, allowing extremal black holes to decay. This conjecture is supported by a number of non-trivial examples in string theory. It implies the necessary presence of new physics beneath the Planck scale, not far from the GUT scale, and explains why some apparently natural models of inflation resist an embedding in string theory.

STRING THEORY, QUANTUM MECHANICS AND NONCOMMUTATIVE GEOMETRY: A NEW PERSPECTIVE ON THE GRAVITATIONAL DYNAMICS OF D0-BRANES

We do not know the symmetries underlying string theory. Furthermore, there must exist an inherently quantum, and space–time independent, formulation of this theory. Independent of string theory, there should exist a description of quantum mechanics which does not refer to a classical space–time manifold. We propose such a formulation of quantum mechanics, based on noncommutative geometry. This description reduces to standard quantum mechanics, whenever an external classical space–time is available. However, near the Planck energy scale, self-gravity effects modify the Schrödinger equation to the non-linear Doebner–Goldin equation. Remarkably, this non-linear equation also arises in the quantum dynamics of D0-branes. This suggests that the noncommutative quantum dynamics proposed here is actually the quantum gravitational dynamics of D0-branes, and that automorphism invariance is a symmetry of string theory.

Proton decay, Yukawa couplings and underlying gauge symmetry in string theory

In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that ( D ¯ , L ) are different from H ¯ ( 5 ¯ ) in their origins. In this article, we consider a possibility that they come from different irreducible components in g / h . Requiring that all the Yukawa coupling constants of quarks and leptons be generated from the super-Yang–Mills interactions of G, we found in the context of Georgi–Glashow H = SU ( 5 ) unification that the minimal choice of G is E 7 and E 8 is the only alternative. This idea is systematically implemented in heterotic String, M theory and F theory, confirming the absence of dimension 4 proton decay operators. Not only H = SU ( 5 ) but also G constrain operators of effective field theories, providing non-trivial information.

High-Energy Zero-Norm States and Symmetries of String Theory

High-energy limit of zero-norm states in the old covariant first quantized spectrum of the 26D open bosonic string, together with the assumption of a smooth behavior of string theory in this limit, are used to derive infinitely many linear relations among the leading high-energy, fixed-angle behavior of four-point functions of different string states. As a result, ratios among all high-energy scattering amplitudes of four arbitrary string states can be calculated algebraically and the leading order amplitudes can be expressed in terms of that of four tachyons as conjectured by Gross in 1988. A dual calculation can also be performed and equivalent results are obtained by taking the high-energy limit of Virasoro constraints. Finally, we compute all high-energy scattering amplitudes of three tachyons and one massive state at the leading order by saddle-point approximation to verify our results.

CPT and Other Symmetries in String/M Theory

We initiate a search for non-perturbative consistency conditions in M theory. Some non-perturbative conditions are already known in Type I theories; we review these and search for others. We focus principally on possible anomalies in discrete symmetries. It is generally believed that discrete symmetries in string theories are gauge symmetries, so anomalies would provide evidence for inconsistencies. Using the orbifold cosmic string construction, we give some evidence that the symmetries we study are gauged. We then search for anomalies in discrete symmetries in a variety of models, both with and without supersymmetry. In symmetric orbifold models we extend previous searches, and show in a variety of examples that all anomalies may be canceled by a Green-Schwarz mechanism. We explore some asymmetric orbifold constructions and again find that all anomalies may be canceled this way. Then we turn to Type IIB orientifold models where it is known that even perturbative anomalies are non-universal. In the examples we study, by combining geometric discrete symmetries with continuous gauge symmetries, one may define non-anomalous discrete symmetries already in perturbation theory; in other cases, the anomalies are universal. Finally, we turn to the question of CPT conservation in string/M theory. It is well known that CPT is conserved in all string perturbation expansions; here in a number of examples for which a non-perturbative formulation is available we provide evidence that it is conserved exactly.

Adventures in thermal duality. II. Towards a duality-covariant string thermodynamics

In a recent companion paper, we observed that the rules of ordinary thermodynamics generally fail to respect thermal duality, a symmetry of string theory under which the physics at temperature T is related to the physics at the inverse temperature 1/T. Even when the free energy and internal energy exhibit the thermal duality symmetry, the entropy and specific heat are defined in such a way that this symmetry is destroyed. In this paper, we propose a modification of the traditional definitions of these quantities, yielding a manifestly duality-covariant thermodynamics. At low temperatures, these modifications produce "corrections" to the standard definitions of entropy and specific heat which are suppressed by powers of the string scale. These corrections may nevertheless be important for the full development of a consistent string thermodynamics. We find, for example, that the string-corrected entropy can be smaller than the usual entropy at high temperatures, suggesting a possible connection with the holographic principle. We also discuss some outstanding theoretical issues prompted by our approach.

Gauge Theory and Calibrated Geometry, I

The geometry of submanifolds is intimately related to the theory of functions and vector bundles. It has been of fundamental importance to find out how those two objects interact in many geometric and physical problems. A typical example of this relation is that the Picard group of line bundles on an algebraic manifold is isomorphic to the group of divisors, which is generated by holomorphic hypersurfaces modulo linear equivalence. A similar correspondence can be made between the K-group of sheaves and the Chow ring of holomorphic cycles. There are two more very recent examples of such a relation. The mirror symmetry in string theory has revealed a deeper phenomenon involving special Lagrangian cycles (cf. [SYZ]). On the other hand, C. Taubes has shown that the Seiberg-Witten invariant coincides with the Gromov-Witten invariant on any symplectic 4-manifolds. In this paper, we will show another natural interaction between Yang-Mills connections, which are critical points of a Yang-Mills action associated to a vector bundle, and minimal submanifolds, which have been studied extensively for years in classical differential geometry and the calculus of variations.

Brane mapping under (−1) FL

We present the evidence that (−1) F L is a nonperturbative symmetry of Type II string theory. We argue that (−1) F L is a symmetry of string theory as much as the SL(2, Z) of the Type II string is and how the branes are mapped under the (−1) F L modding. NS branes are mapped into the NS branes with the same world volume dimensions but with the different chiral structure. Supersymmetric D p-branes (bound with anti-D p branes) are mapped to unstable nonsupersymmetric D p-branes, which has D( p−1)-branes as kink solutions according to Horava [Type IIA D-branes, K Theory, And Matrix Theory, hep-th/9812135].

D-term inflation in superstring theories

An inflationary stage dominated by a D-term avoids the slow-roll problem of inflation in supergravity and may emerge in theories with a non-anomalous or anomalous U(1) gauge symmetry. The most intriguing and commonly invoked possibility is that the Fayet-Iliopoulos D-term triggering inflation is the one emerging in superstring theories. We discuss the complications one has to face when trying to build up a successful D-term inflationary scenario in superstring models. In particular, we show that the “vacuum shifting” phenomenon of string theories is usually very efficient even in the early Universe, thus preventing inflation from taking place. On the other hand, when D-term inflation is free to occur, the presence of a plethora of fields and several non-anomalous additional Abelian symmetries in string theories may help in reconciling the value of the Fayet-Iliopoulos D-term required by the COBE normalization with the value predicted by string theories. We also show that in superstring D-term inflation gravitinos are likely to pose no cosmological problem.

Stable non-BPS states in string theory

Many string theories contain states which are not BPS, but are stable due to charge conservation. In many cases the description of these states in the strong coupling limit remains unknown despite the existence of a weakly coupled dual theory. However, we show that in some cases duality symmetries in string theory do enable us to identify these states in the strong coupling limit and calculate their masses. We also speculate that in some of the other cases the missing states might arise from non-supersymmetric analog of D0-branes.

Duality symmetries in string theory

We review recent progress in our understanding of duality symmetries in string theory.

Hidden finite symmetries in string theory and duality of dualities

Different compactifications of six-dimensional string theory on M 4 × T 2 are considered. Particular attention is given to the roles of the reduced modes as the S and T fields. It is shown that there is a discrete group of invariances of an equilateral triangle hidden in the model. This group is realized as the interchanges of the two-form fields present in the intermediate step of dimensional reduction in five dimensions. The key ingredient for the existence of this group is the presence of an additional U(1) gauge field in five dimensions, arising as the dual of the Kalb-Ramond axion field strength. As a consequence, the theory contains more four-dimensional SL(2, R) representations, with the resulting complex scalar axidilaton related to the components of the Kaluza-Klein vector fields of the naive dimensional reduction. An immediate byproduct of this relationship is a triadic correspondence among the fundamental string, the solitonic string, and a singular Brinkmann pp wave.