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Sample records for heterotic string solutions

  1. Heterotic string solutions and coset conformal field theories

    CERN Document Server

    Giveon, Amit; Tseytlin, Arkady A

    1993-01-01

    We discuss solutions of the heterotic string theory which are analogous to bosonic and superstring backgrounds related to coset conformal field theories. A class of exact `left-right symmetric' solutions is obtained by supplementing the metric, antisymmetric tensor and dilaton of the superstring solutions by the gauge field background equal to the generalised Lorentz connection with torsion. As in the superstring case, these backgrounds are $\\a'$-independent, i.e. have a `semiclassical' form. The corresponding heterotic string sigma model is obtained from the combination of the (1,0) supersymmetric gauged WZNW action with the action of internal fermions coupled to the target space gauge field. The pure (1,0) supersymmetric gauged WZNW theory is anomalous and does not describe a consistent heterotic string solution. We also find (to the order $\\alpha'^3$) a two-dimensional perturbative heterotic string solution with the trivial gauge field background. To the leading order in $\\alpha'$ it coincides with the kno...

  2. A solution to the decompactification problem in chiral heterotic strings

    Directory of Open Access Journals (Sweden)

    Ioannis Florakis

    2017-08-01

    Full Text Available We present a solution to the decompactification problem of gauge thresholds in chiral heterotic string theories with two large extra dimensions, where supersymmetry is spontaneously broken by the Scherk–Schwarz mechanism. Whenever the Kaluza–Klein scale that controls supersymmetry breaking is much lower than the string scale, the infinite towers of heavy states contribute non-trivially to the renormalisation of gauge couplings, which typically grow linearly with the large volume of the internal space and invalidate perturbation theory. We trace the origin of the decompactification problem to properties of the six dimensional theory obtained in the infinite volume limit and show that thresholds may instead exhibit logarithmic volume dependence and we provide the conditions for this to occur. We illustrate this mechanism with explicit string constructions where the decompactification problem does not occur.

  3. Heterotic cosmic strings

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie; Krause, Axel

    2006-01-01

    We show that all three conditions for the cosmological relevance of heterotic cosmic strings, the right tension, stability and a production mechanism at the end of inflation, can be met in the strongly coupled M-theory regime. Whereas cosmic strings generated from weakly coupled heterotic strings have the well-known problems posed by Witten in 1985, we show that strings arising from M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic M-theory compactifications solve these problems in an elegant fashion

  4. Confusing the heterotic string

    International Nuclear Information System (INIS)

    Benett, D.L.; Mizrachi, L.

    1986-01-01

    A confusion mechanism is proposed as a global modification of the heterotic string model. It envolves a confusion hypersurface across which the two E 8 's of the heterotic string are permuted. A remarkable numerical coincidence is found which prevents an inconsistency in the model. The low energy limit of this theory (after compactification) is typically invariant under one E 8 only, thereby removing the shadow world from the original model. (orig.)

  5. Confusing the heterotic string

    Science.gov (United States)

    Benett, D.; Brene, N.; Mizrachi, Leah; Nielsen, H. B.

    1986-10-01

    A confusion mechanism is proposed as a global modification of the heterotic string model. It envolves a confusion hypersurface across which the two E 8's of the heterotic string are permuted. A remarkable numerical coincidence is found which prevents an inconsistency in the model. The low energy limit of this theory (after compactification) is typically invariant under one E 8 only, thereby removing the shadow world from the original model.

  6. Confusing the heterotic string

    Energy Technology Data Exchange (ETDEWEB)

    Benett, D.L.; Brene, N.; Nielsen, H.B.; Mizrachi, L.

    1986-10-02

    A confusion mechanism is proposed as a global modification of the heterotic string model. It envolves a confusion hypersurface across which the two E/sub 8/'s of the heterotic string are permuted. A remarkable numerical coincidence is found which prevents an inconsistency in the model. The low energy limit of this theory (after compactification) is typically invariant under one E/sub 8/ only, thereby removing the shadow world from the original model.

  7. The heterotic string

    International Nuclear Information System (INIS)

    Gross, D.J.

    1986-01-01

    Traditional string theories, either bosonic or supersymmetric, came in two varieties, closed string theories and open string theories. Closed string are neutral objects which describe at low energies gravity or supergravity. Open strings have geometrically invariant ends to which charge can be attached, thereby obtaining, in addition to gravity, Yang-Mills gauge interactions. Recently a new kind of string theory was discovered--the heterotic string, which is a chiral hybrid of the closed superstring and the closed bosonic string, and which produces by an internal dynamical mechanism gauge interactions of a totally specified kind. Although this theory is found in an attempt to produce a superstring theory which would yield a low energy E/sub 8/xE/sub 8/ supersymmetric, anomaly free, gauge theory, as suggested by the anomaly cancellation mechanism of Green and Schwarz, it fits naturally into the general framework of consistent string theories

  8. Heterotic string construction

    International Nuclear Information System (INIS)

    Schellekens, A.N.

    1989-01-01

    In this paper an elementary introduction to the principles of four-dimensional string construction will be given. Although the emphasis is on lattice constructions, almost all results have further, and often quite straightforward generalizations to other constructions. Since heterotic strings look phenomenologically more promising than type-II theories the authors only consider the former, although everything can easily be generalized to type-II theories. Some additional aspects of lattice constructions are discussed, and an extensive review can be found

  9. Heterotic strings on homogeneous spaces

    International Nuclear Information System (INIS)

    Israel, D.; Kounnas, C.; Orlando, D.; Petropoulos, P.M.

    2005-01-01

    We construct heterotic string backgrounds corresponding to families of homogeneous spaces as exact conformal field theories. They contain left cosets of compact groups by their maximal tori supported by NS-NS 2-forms and gauge field fluxes. We give the general formalism and modular-invariant partition functions, then we consider some examples such as SU(2)/U(1)∝S 2 (already described in a previous paper) and the SU(3)/U(1) 2 flag space. As an application we construct new supersymmetric string vacua with magnetic fluxes and a linear dilaton. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  10. Dyonic black hole in heterotic string theory

    International Nuclear Information System (INIS)

    Jatkar, D.P.; Mukherji, S.

    1997-01-01

    We study some features of the dyonic black hole solution in heterotic string theory on a six-torus. This solution has 58 parameters. Of these, 28 parameters denote the electric charge of the black hole, another 28 correspond to the magnetic charge, and the other two parameters are the mass and the angular momentum of the black hole. We discuss the extremal limit and show that in various limits it reduces to the known black hole solutions. The solutions saturating the Bogomolnyi bound are identified. An explicit solution is presented for the non-rotating dyonic black hole. (orig.)

  11. Non-Kaehler heterotic string solutions with non-zero fluxes and non-constant dilaton

    Energy Technology Data Exchange (ETDEWEB)

    Fernández, Marisa [Universidad del País Vasco,Facultad de Ciencia y Tecnología, Departamento de Matemáticas,Apartado 644, 48080 Bilbao (Spain); Ivanov, Stefan [University of Sofia “St. Kl. Ohridski”,Faculty of Mathematics and Informatics,Blvd. James Bourchier 5, 1164 Sofia (Bulgaria); Institute of Mathematics and Informatics, Bulgarian Academy of Sciences (Bulgaria); Ugarte, Luis [Departamento de Matemáticas - I.U.M.A., Universidad de Zaragoza,Campus Plaza San Francisco, 50009 Zaragoza (Spain); Vassilev, Dimiter [Department of Mathematics and Statistics, University of New Mexico,Albuquerque, New Mexico, 87131-0001 (United States)

    2014-06-12

    Conformally compact and complete smooth solutions to the Strominger system with non vanishing flux, non-trivial instanton and non-constant dilaton using the first Pontrjagin form of the (−)-connection on 6-dimensional non-Kähler nilmanifold are presented. In the conformally compact case the dilaton is determined by the real slices of the elliptic Weierstrass function. The dilaton of non-compact complete solutions is given by the fundamental solution of the Laplacian on R{sup 4}. All solutions satisfy the heterotic equations of motion up to the first order of α{sup ′}.

  12. Anomaly cancellation and smooth non-Kahler solutions in heterotic string theory

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie; Fu Jixiang; Tseng, L.-S.; Yau, S.-T.

    2006-01-01

    We show that six-dimensional backgrounds that are T 2 bundle over a Calabi-Yau two-fold base are consistent smooth solutions of heterotic flux compactifications. We emphasize the importance of the anomaly cancellation condition which can only be satisfied if the base is K3 while a T 4 base is excluded. The conditions imposed by anomaly cancellation for the T 2 bundle structure, the dilaton field, and the holomorphic stable bundles are analyzed and the solutions determined. Applying duality, we check the consistency of the anomaly cancellation constraints with those for flux backgrounds of M-theory on eight-manifolds

  13. EFFECTIVE ACTIONS FOR HETEROTIC STRING THEORY

    NARCIS (Netherlands)

    SUELMANN, H

    Heterotic String Theory is an attempt to construct a description of nature that is more satisfying than the Standard Model. A major problem is that it is very difficult to do explicit calculations in string theory. Therefore, it is useful to construct a 'normal' field theory that approximates HST.

  14. Cosmological constant versus free energy for heterotic strings

    International Nuclear Information System (INIS)

    Alvarez, E.; Osorio, M.A.R.

    1988-01-01

    A detailed analysis is made of the modular-invariant formulation of the free energy of heterotic strings. Several instances are pointed out in which a duality formula can be obtained, and its physical implications are discussed. The interplay between the free energy of a given heterotic string and the cosmological constant of the toroidal compactification of another heterotic string is emphasized. (orig.)

  15. Instantons, hypermultiplets and the heterotic string

    International Nuclear Information System (INIS)

    Halmagyi, Nick; Melnikov, Ilarion V.; Sethi, Savdeep

    2007-01-01

    Hypermultiplet couplings in type IIA string theory on a Calabi-Yau space can be quantum corrected by D2-brane instantons wrapping special Lagrangian cycles. On the other hand, hypermultiplet couplings in the heterotic string on a K3 surface are corrected by world-sheet instantons wrapping curves. In a class of examples, we relate these two sets of instanton corrections. We first present an analogue of the c-map for the heterotic string via a dual flux compactification of M-theory. Using this duality, we propose two ways of capturing quantum corrections to hypermultiplets. We then use the orientifold limit of certain F-theory compactifications to relate curves in K3 to special Lagrangians in dual type IIA compactifications. We conclude with some results from perturbative string theory for hypermultiplet F-terms and a conjecture about the topology of brane instantons

  16. The confusion mechanism and the heterotic string

    International Nuclear Information System (INIS)

    Bennett, D.L.; Mizrachi, L.; Nielsen, H.B.; Brene, N.

    1987-01-01

    The confusion mechanism introduced earlier in connection with the gauge glass model is here discussed in the context of field theories involving symmetry groups which have outer automorphisms. The heterotic string with an E 8 x E 8 symmetry may be influenced by confusion with the result that only one E 8 group survives and the shadow world disappears. (orig.)

  17. Exophobic Quasi-Realistic Heterotic String Vacua

    CERN Document Server

    Assel, Benjamin; Faraggi, Alon E; Kounnas, Costas; Rizos, John

    2009-01-01

    We demonstrate the existence of heterotic-string vacua that are free of massless exotic fields. The need to break the non-Abelian GUT symmetries in k=1 heterotic-string models by Wilson lines, while preserving the GUT embedding of the weak-hypercharge and the GUT prediction sin^2\\theta_w(M(GUT))=3/8, necessarily implies that the models contain states with fractional electric charge. Such states are severely restricted by observations, and must be confined or sufficiently massive and diluted. We construct the first quasi-realistic heterotic-string models in which the exotic states do not appear in the massless spectrum, and only exist, as they must, in the massive spectrum. The SO(10) GUT symmetry is broken to the Pati-Salam subgroup. Our PS heterotic-string models contain adequate Higgs representations to break the GUT and electroweak symmetry, as well as colour Higgs triplets that can be used for the missing partner mechanism. By statistically sampling the space of Pati-Salam vacua we demonstrate the abundan...

  18. The confusion mechanism and the heterotic string

    International Nuclear Information System (INIS)

    Bennett, D.L.; Nielsen, H.B.; Brene, N.; Mizrachi, L.

    1986-01-01

    The confusion mechanism introduced earlier in connection with the gauge glass model is here discussed in the context of field theories involving symmetry groups which have outer automorphisms. The heterotic string with an E 8 8xE 8 symmetry may be influence by confusion with the result that only one E 8 group survives and the shadow world disappears. (author)

  19. Heterotic String/F-theory Duality from Mirror Symmetry

    CERN Document Server

    Berglund, Per

    1998-01-01

    We use local mirror symmetry in type IIA string compactifications on Calabi-Yau n+1 folds $X_{n+1}$ to construct vector bundles on (possibly singular) elliptically fibered Calabi-Yau n-folds Z_n. The interpretation of these data as valid classical solutions of the heterotic string compactified on Z_n proves F-theory/heterotic duality at the classical level. Toric geometry is used to establish a systematic dictionary that assigns to each given toric n+1-fold $X_{n+1}$ a toric n fold Z_n together with a specific family of sheafs on it. This allows for a systematic construction of phenomenologically interesting d=4 N=1 heterotic vacua, e.g. on deformations of the tangent bundle, with grand unified and SU(3)\\times SU(2) gauge groups. As another application we find non-perturbative gauge enhancements of the heterotic string on singular Calabi-Yau manifolds and new non-perturbative dualities relating heterotic compactifications on different manifolds.

  20. Kahler stabilized, modular invariant heterotic string models

    International Nuclear Information System (INIS)

    Gaillard, Mary K.; Gaillard, Mary K.; Nelson, Brent D.

    2007-01-01

    We review the theory and phenomenology of effective supergravity theories based on orbifold compactifications of the weakly-coupled heterotic string. In particular, we consider theories in which the four-dimensional theory displays target space modular invariance and where the dilatonic mode undergoes Kahler stabilization. A self-contained exposition of effective Lagrangian approaches to gaugino condensation and heterotic string theory is presented, leading to the development of the models of Bintruy, Gaillard and Wu. Various aspects of the phenomenology of this class of models are considered. These include issues of supersymmetry breaking and superpartner spectra, the role of anomalous U(1) factors, issues of flavor and R-parity conservation, collider signatures, axion physics, and early universe cosmology. For the vast majority of phenomenological considerations the theories reviewed here compare quite favorably to other string-derived models in the literature. Theoretical objections to the framework and directions for further research are identified and discussed

  1. Seesaw neutrinos from the heterotic string

    International Nuclear Information System (INIS)

    Buchmueller, W.; Hamaguchi, K.; Ramos-Sanchez, S.; Ratz, M.

    2007-03-01

    We study the possibility of realizing the neutrino seesaw mechanism in the E 8 x E 8 heterotic string. In particular, we consider its Z 6 orbifold compactifications leading to the supersymmetric standard model gauge group and matter content. We find that these models possess all the necessary ingredients for the seesaw mechanism, including the required Dirac Yukawa couplings and large Majorana mass terms. We argue that this situation is quite common in heterotic orbifolds. In contrast to the conventional seesaw of grand unified theories (GUTs), no large GUT representations are needed to generate the Majorana mass terms. The total number of right-handed neutrinos can be very large, up to O(100). (orig.)

  2. Covariant heterotic strings and odd self-dual lattices

    International Nuclear Information System (INIS)

    Lerche, W.; Luest, D.

    1987-01-01

    We investigate the implications of modular invariance for covariantly formulated heterotic strings. It is shown that modular invariant heterotic strings are characterized by odd self-dual lorentzian lattices which include charges of the bosonized superconformal ghosts. The proof of modular invariance involves the anomaly in the ghost number current in a crucial way. (orig.)

  3. Massive neutral particles on heterotic string theory

    International Nuclear Information System (INIS)

    Olivares, Marco; Villanueva, J.R.

    2013-01-01

    The motion of massive particles in the background of a charged black hole in heterotic string theory, which is characterized by a parameter α, is studied in detail in this paper. Since it is possible to write this space-time in the Einstein frame, we perform a quantitative analysis of the time-like geodesics by means of the standard Lagrange procedure. Thus, we obtain and solve a set of differential equations and then we describe the orbits in terms of the elliptic p-Weierstrass function. Also, by making an elementary derivation developed by Cornbleet (Am. J. Phys. 61(7):650-651, 1993) we obtain the correction to the angle of advance of perihelion to first order in α, and thus, by comparing with Mercury's data we give an estimation for the value of this parameter, which yields an heterotic solar charge Q s un ≅ 0.728 [Km]=0.493 M s un. Therefore, in addition to the study on null geodesics performed by Fernando (Phys. Rev. D 85:024033, 2012), this work completes the geodesic structure for this class of space-time. (orig.)

  4. Massive neutral particles on heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Olivares, Marco [Pontificia Universidad de Catolica de Valparaiso, Instituto de Fisica, Valparaiso (Chile); Villanueva, J.R. [Universidad de Valparaiso, Departamento de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile)

    2013-12-15

    The motion of massive particles in the background of a charged black hole in heterotic string theory, which is characterized by a parameter {alpha}, is studied in detail in this paper. Since it is possible to write this space-time in the Einstein frame, we perform a quantitative analysis of the time-like geodesics by means of the standard Lagrange procedure. Thus, we obtain and solve a set of differential equations and then we describe the orbits in terms of the elliptic p-Weierstrass function. Also, by making an elementary derivation developed by Cornbleet (Am. J. Phys. 61(7):650-651, 1993) we obtain the correction to the angle of advance of perihelion to first order in {alpha}, and thus, by comparing with Mercury's data we give an estimation for the value of this parameter, which yields an heterotic solar charge Q{sub s}un {approx_equal} 0.728 [Km]=0.493 M{sub s}un. Therefore, in addition to the study on null geodesics performed by Fernando (Phys. Rev. D 85:024033, 2012), this work completes the geodesic structure for this class of space-time. (orig.)

  5. Connecting the ambitwistor and the sectorized heterotic strings

    Science.gov (United States)

    Azevedo, Thales; Jusinskas, Renann Lipinski

    2017-10-01

    The sectorized description of the (chiral) heterotic string using pure spinors has been misleadingly viewed as an infinite tension string. One evidence for this fact comes from the tree level 3-point graviton amplitude, which we show to contain the usual Einstein term plus a higher curvature contribution. After reintroducing a dimensionful parameter ℓ in the theory, we demonstrate that the heterotic model is in fact two-fold, depending on the choice of the supersymmetric sector, and that the spectrum also contains one massive (open string like) multiplet. By taking the limit ℓ → ∞, we finally show that the ambitwistor string is recovered, reproducing the unexpected heterotic state in Mason and Skinner's RNS description.

  6. Heterotic string in an arbitrary background field

    International Nuclear Information System (INIS)

    Sen, A.

    1985-01-01

    An expression for the light-cone gauge action for the first-quantized heterotic string in the presence of arbitrary background gauge, gravitational, and antisymmetric tensor fields is derived. The result is a two-dimensional local field theory with N = 1/2 supersymmetry. The constraints imposed on the background fields in order to make this theory one-loop finite are derived. These constraints are identical to the equations of motion for the massless fields at the linearized level. Finally, it is shown that if there is no background antisymmetric tensor field, and if the gauge connection is set equal to the spin connection, the effective action is that of an N = 1 supersymmetric nonlinear and N = 2 supersymmetric Georgi-Glashow models the occurrence of the fermion fractionization is the necessity; the ignorance of it results in the inconsistency in the perturbative calculation of the mass splittings among the members of the supermultiplets. The notable feature of our result is that the degeneracy due to the Jackiw-Rebbi zero mode is not independent of the one required by the supersymmetry, suggesting a nontrivial structure in embedding the topology of Higgs fields into supersymmetric gauge theories

  7. O(6,22) BPS configurations of the heterotic string

    International Nuclear Information System (INIS)

    Behrndt, K.; Kallosh, R.

    1996-01-01

    We present a static multicenter magnetic solution of toroidally compactified heterotic string theory, which is T-duality covariant. The space-time geometry depends on the mass M and on the O(6,22) norm N of the magnetic charges. For a different range of parameters the (M,N) solution includes (1) two-independent-positive-parameter extremal magnetic black holes with a nonsingular geometry in a stringy frame (a=1 black holes included), (2) a=√3 extremal black holes, and (3) singular massive and massless magnetic white holes (repulsons). The electric multicenter solution is also given in an O(6,22)-symmetric form. copyright 1996 The American Physical Society

  8. Covarient quantization of heterotic strings in supersymmetric chiral boson formulation

    International Nuclear Information System (INIS)

    Yu, F.

    1992-01-01

    This dissertation presents the covariant supersymmetric chiral boson formulation of the heterotic strings. The main feature of this formulation is the covariant quantization of the so-called leftons and rightons -- the (1,0) supersymmetric generalizations of the world-sheet chiral bosons -- that constitute basic building blocks of general heterotic-type string models. Although the (Neveu-Schwarz-Ramond or Green-Schwarz) heterotic strings provide the most realistic string models, their covariant quantization, with the widely-used Siegel formalism, has never been rigorously carried out. It is clarified in this dissertation that the covariant Siegel formalism is pathological upon quantization. As a test, a general classical covariant (NSR) heterotic string action that has the Siegel symmetry is constructed in arbitrary curved space-time coupled to (1,0) world-sheet super-gravity. In the light-cone gauge quantization, the critical dimensions are derived for such an action with leftons and rightons compactified on group manifolds G L x G R . The covariant quantization of this action does not agree with the physical results in the light-cone gauge quantization. This dissertation establishes a new formalism for the covariant quantization of heterotic strings. The desired consistent covariant path integral quantization of supersymmetric chiral bosons, and thus the general (NSR) heterotic-type strings with leftons and rightons compactified on torus circle-times d L S 1 x circle-times d R S 1 are carried out. An infinite set of auxiliary (1,0) scalar superfields is introduced to convert the second-class chiral constraint into first-class ones. The covariant gauge-fixed action has an extended BRST symmetry described by the graded algebra GL(1/1). A regularization respecting this symmetry is proposed to deal with the contributions of the infinite towers of auxiliary fields and associated ghosts

  9. Discrete symmetries in the heterotic-string landscape

    International Nuclear Information System (INIS)

    Athanasopoulos, P

    2015-01-01

    We describe a new type of discrete symmetry that relates heterotic-string models. It is based on the spectral flow operator which normally acts within a general N = (2, 2) model and we use this operator to construct a map between N = (2, 0) models. The landscape of N = (2, 0) models is of particular interest among all heterotic-string models for two important reasons: Firstly, N =1 spacetime SUSY requires (2, 0) superconformal invariance and secondly, models with the well motivated by the Standard Model SO(10) unification structure are of this type. This idea was inspired by a new discrete symmetry in the space of fermionic ℤ 2 × ℤ 2 heterotic-string models that exchanges the spinors and vectors of the SO(10) GUT group, dubbed spinor-vector duality. We will describe how to generalize this to arbitrary internal rational Conformal Field Theories. (paper)

  10. Discrete symmetries in the heterotic-string landscape

    Science.gov (United States)

    Athanasopoulos, P.

    2015-07-01

    We describe a new type of discrete symmetry that relates heterotic-string models. It is based on the spectral flow operator which normally acts within a general N = (2, 2) model and we use this operator to construct a map between N = (2, 0) models. The landscape of N = (2, 0) models is of particular interest among all heterotic-string models for two important reasons: Firstly, N =1 spacetime SUSY requires (2, 0) superconformal invariance and secondly, models with the well motivated by the Standard Model SO(10) unification structure are of this type. This idea was inspired by a new discrete symmetry in the space of fermionic ℤ2 × ℤ2 heterotic-string models that exchanges the spinors and vectors of the SO(10) GUT group, dubbed spinor-vector duality. We will describe how to generalize this to arbitrary internal rational Conformal Field Theories.

  11. Torsion, supersymmetry, and the heterotic string

    International Nuclear Information System (INIS)

    Curtright, T.

    1985-01-01

    The dynamical effects of torsion are summarized for bosonic and supersymmetric sigma models in two spacetime dimensions. Analogous structure for the heterotic superstring is discussed, including the presence of nonlinear realizations of supersymmetry on the world-sheet. 27 refs

  12. On the elliptic genus of three E-strings and heterotic strings

    International Nuclear Information System (INIS)

    Cai, Wenhe; Huang, Min-xin; Sun, Kaiwen

    2015-01-01

    A precise formula for the elliptic genus of three E-strings is presented. The related refined free energy coincides with the result calculated from topological string on local half K3 Calabi-Yau threefold up to genus twelve. The elliptic genus of three heterotic strings computed from M9 domain walls matches with the result from orbifold formula to high orders. This confirms the n=3 case of the recent conjecture that n pairs of E-strings can recombine into n heterotic strings.

  13. The non-minimal heterotic pure spinor string in a curved background

    Energy Technology Data Exchange (ETDEWEB)

    Chandia, Osvaldo [Facultad de Artes Liberales and Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez,Diagonal Las Torres 2640, Peñalolén, Santiago (Chile)

    2014-03-21

    We study the non-minimal pure spinor string in a curved background. We find that the minimal BRST invariance implies the existence of a non-trivial stress-energy tensor for the minimal and non-minimal variables in the heterotic curved background. We find constraint equations for the b ghost. We construct the b ghost as a solution of these constraints.

  14. Anomaly, fluxes and (2,0) heterotic-string compactifications

    International Nuclear Information System (INIS)

    Gillard, Joe; Papadopoulos, George; Tsimpis, Dimitrios

    2003-01-01

    We compute the corrections to heterotic-string backgrounds with (2,0) world-sheet supersymmetry, up to two loops in sigma-model perturbation theory. We investigate the conditions for these backgrounds to preserve spacetime supersymmetry and we find that a sufficient requirement for consistency is the applicability of the ∂ ∂-bar-lemma. In particular, we investigate the α' corrections to (2,0) heterotic-string compactifications and we find that the Calabi-Yau geometry of the internal space is deformed to a hermitean one. We show that at first order in α', the heterotic anomaly-cancellation mechanism does not induce any lifting of moduli. We explicitly compute the corrections to the conifold and to the U(n)-invariant Calabi-Yau metric at first order in α'. We also find a generalization of the gauge-field equations, compatible with the Donaldson equations on conformally-balanced hermitean manifolds. (author)

  15. Lattice classification of the four-dimensional heterotic strings

    International Nuclear Information System (INIS)

    Balog, J.; Forgacs, P.; Vecsernyes, P.; Horvath, Z.

    1987-06-01

    A lattice slicing procedure is proposed which leads to the classification of all four-dimensional chiral heterotic strings based on Conway and Sloane's 22-dimensional self-dual Euclidean lattices. By reversing this procedure it is possible to construct all these theories. (author)

  16. On the cosmological constant in the heterotic string theory

    International Nuclear Information System (INIS)

    Gava, E.; Iengo, R.

    1987-01-01

    We examine the possible physical assumptions which can be made in the heterotic string theory in order to derive the vanishing of the cosmological constant within the theory of modular forms on the moduli space. It seems that more mathematical information is needed to reach a definite result. (author)

  17. Effective action and β-functions for the heterotic string

    International Nuclear Information System (INIS)

    Foakes, A.P.; Mohammedi, N.; Ross, D.A.

    1988-01-01

    The results of the calculation of the metric β-function for the heterotic string sigma model up to three loops are presented and it is shown that although this β-function is non vanishing it is compatible with an O((α') 2 ) effective action in which there are no terms cubic in the Riemann tensor or gauge field strength. (orig.)

  18. Heterotic sigma models and non-linear strings

    International Nuclear Information System (INIS)

    Hull, C.M.

    1986-01-01

    The two-dimensional supersymmetric non-linear sigma models are examined with respect to the heterotic string. The paper was presented at the workshop on :Supersymmetry and its applications', Cambridge, United Kingdom, 1985. The non-linear sigma model with Wess-Zumino-type term, the coupling of the fermionic superfields to the sigma model, super-conformal invariance, and the supersymmetric string, are all discussed. (U.K.)

  19. E(lementary) Strings in Six-Dimensional Heterotic F-Theory

    OpenAIRE

    Choi, Kang-Sin; Rey, Soo-Jong

    2017-01-01

    Using E-strings, we can analyze not only six-dimensional superconformal field theories but also probe vacua of non-perturabative heterotic string. We study strings made of D3-branes wrapped on various two-cycles in the global F-theory setup. We claim that E-strings are elementary in the sense that various combinations of E-strings can form M-strings as well as heterotic strings and new kind of strings, called G-strings. Using them, we show that emissions and combinations of heterotic small in...

  20. Heterotic-type II string duality and the H-monopole problem

    CERN Document Server

    Girardello, L; Zaffaroni, A

    1996-01-01

    Since T-duality has been proved only perturbatively and most of the heterotic states map into solitonic, non-perturbative, type II states, the 6-dimensional string-string duality between the heterotic string and the type II string is not sufficient to prove the S-duality of the former, in terms of the known T-duality of the latter. We nevertheless show in detail that perturbative T-duality, together with the heterotic-type II duality, does imply the existence of heterotic H-monopoles, with the correct multiplicity and multiplet structure. This construction is valid at a generic point in the moduli space of heterotic toroidal compactifications.

  1. sigma model approach to the heterotic string theory

    International Nuclear Information System (INIS)

    Sen, A.

    1985-09-01

    Relation between the equations of motion for the massless fields in the heterotic string theory, and the conformal invariance of the sigma model describing the propagation of the heterotic string in arbitrary background massless fields is discussed. It is emphasized that this sigma model contains complete information about the string theory. Finally, we discuss the extension of the Hull-Witten proof of local gauge and Lorentz invariance of the sigma-model to higher order in α', and the modification of the transformation laws of the antisymmetric tensor field under these symmetries. Presence of anomaly in the naive N = 1/2 supersymmetry transformation is also pointed out in this context. 12 refs

  2. Compactifications of the Heterotic string with unitary bundles

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, T.

    2006-05-23

    In this thesis we investigate a large new class of four-dimensional supersymmetric string vacua defined as compactifications of the E{sub 8} x E{sub 8} and the SO(32) heterotic string on smooth Calabi-Yau threefolds with unitary gauge bundles and heterotic five-branes. The first part of the thesis discusses the implementation of this idea into the E{sub 8} x E{sub 8} heterotic string. After specifying a large class of group theoretic embeddings featuring unitary bundles, we analyse the effective four-dimensional N=1 supergravity upon compactification. From the gauge invariant Kaehler potential for the moduli fields we derive a modification of the Fayet-Iliopoulos D-terms arising at one-loop in string perturbation theory. From this we conjecture a one-loop deformation of the Hermitian Yang-Mills equation and introduce the idea of {lambda}-stability as the perturbatively correct stability concept generalising the notion of Mumford stability valid at tree-level. We then proceed to a definition of SO(32) heterotic vacua with unitary gauge bundles in the presence of heterotic five-branes and find agreement of the resulting spectrum with the S-dual framework of Type I/Type IIB orientifolds. A similar analysis of the effective four-dimensional supergravity is performed. Further evidence for the proposed one-loop correction to the stability condition is found by identifying the heterotic corrections as the S-dual of the perturbative part of {pi}-stability as the correct stability concept in Type IIB theory. After reviewing the construction of holomorphic stable vector bundles on elliptically fibered Calabi-Yau manifolds via spectral covers, we provide semi-realistic examples for SO(32) heterotic vacua with Pati-Salam and MSSM-like gauge sectors. We finally discuss the construction of realistic vacua with flipped SU(5) GUT and MSSM gauge group within the E{sub 8} x E{sub 8} framework, based on the embedding of line bundles into both E{sub 8} factors. Some of the appealing

  3. A heterotic N=2 string with space-time supersymmetry

    International Nuclear Information System (INIS)

    Bellucci, S.; Galajinsky, A.; Lechtenfeld, O.

    2001-02-01

    It is reconsidered the issue of embedding space-time fermions into the four dimensional N=2 world-sheet supersymmetric string. A new heterotic theory is constructed, taking the right-movers from the N =4 topological extension of the conventional N=2 string but a c=0 conformal field theory supporting target-space supersymmetry for the left-moving sector. The global bosonic symmetry of the full formalism proves to be U(1,1), just as in the usual N=2 string. Quantization reveals a spectrum of only two physical states, one boson and one fermion, which fall in a multiplet of (1,0) supersymmetry

  4. Towards matter inflation in heterotic string theory

    International Nuclear Information System (INIS)

    Antusch, Stefan; Erdmenger, Johanna; Halter, Sebastian; Dutta, Koushik

    2011-02-01

    Recently, a class of inflation models in supergravity with gauge non-singlet matter fields as the inflaton has been proposed. It is based on a 'tribrid' structure in the superpotential and on a 'Heisenberg symmetry' for solving the η-problem. We suggest that a generalization of this model class may be suitable for realising inflation in heterotic orbifold compactifications, where the Heisenberg symmetry is a property of the tree-level Kaehler potential of untwisted matter fields. We discuss moduli stabilization in this setup and propose a mechanism to stabilize the modulus associated to the inflaton, which respects the symmetry in the large radius limit. Inflation ends via a waterfall phase transition, as in hybrid inflation. We give conditions which have to be satisfied for realising inflation along these lines in the matter sector of heterotic orbifolds. (orig.)

  5. Towards matter inflation in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Antusch, Stefan; Erdmenger, Johanna; Halter, Sebastian [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany); Dutta, Koushik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-02-15

    Recently, a class of inflation models in supergravity with gauge non-singlet matter fields as the inflaton has been proposed. It is based on a 'tribrid' structure in the superpotential and on a 'Heisenberg symmetry' for solving the {eta}-problem. We suggest that a generalization of this model class may be suitable for realising inflation in heterotic orbifold compactifications, where the Heisenberg symmetry is a property of the tree-level Kaehler potential of untwisted matter fields. We discuss moduli stabilization in this setup and propose a mechanism to stabilize the modulus associated to the inflaton, which respects the symmetry in the large radius limit. Inflation ends via a waterfall phase transition, as in hybrid inflation. We give conditions which have to be satisfied for realising inflation along these lines in the matter sector of heterotic orbifolds. (orig.)

  6. Holomorphic Yukawa couplings in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Blesneag, Stefan [Rudolf Peierls Centre for Theoretical Physics, Oxford University,1 Keble Road, Oxford, OX1 3NP (United Kingdom); Buchbinder, Evgeny I. [The University of Western Australia,35 Stirling Highway, Crawley WA 6009 (Australia); Candelas, Philip [Mathematical Institute, University of Oxford,Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG (United Kingdom); Lukas, Andre [Rudolf Peierls Centre for Theoretical Physics, Oxford University,1 Keble Road, Oxford, OX1 3NP (United Kingdom)

    2016-01-26

    We develop techniques, based on differential geometry, to compute holomorphic Yukawa couplings for heterotic line bundle models on Calabi-Yau manifolds defined as complete intersections in projective spaces. It is shown explicitly how these techniques relate to algebraic methods for computing holomorphic Yukawa couplings. We apply our methods to various examples and evaluate the holomorphic Yukawa couplings explicitly as functions of the complex structure moduli. It is shown that the rank of the Yukawa matrix can decrease at specific loci in complex structure moduli space. In particular, we compute the up Yukawa coupling and the singlet-Higgs-lepton trilinear coupling in the heterotic standard model described in ref. http://dx.doi.org/10.1007/JHEP06(2014)100.

  7. R-symmetries from the orbifolded heterotic string

    International Nuclear Information System (INIS)

    Schmitz, Matthias

    2014-08-01

    We examine the geometric origin of discrete R-symmetries in heterotic orbifold compactifications. By analysing the symmetries of the worldsheet instanton solutions and the underlying geometry, we obtain a scheme that allows us to systematically explore the R-symmetries arising in these compactifications. Applying this scheme to a classification of orbifold geometries, we are able to find all R-symmetries of heterotic orbifolds with Abelian point groups. We show that in the vast majority of cases, the R-symmetries found satisfy anomaly universality constraints, as required in heterotic orbifolds. Then we examine the implications of the presence of these R-symmetries on a class of phenomenologically attractive orbifold compactifications known as the heterotic mini-landscape. We use the technique of Hilbert bases in order to analyse the properties of a vacuum configuration. We find that phenomenologically viable models remain and the main attractive features of the mini-landscape are unaltered.

  8. New infinite-dimensional hidden symmetries for heterotic string theory

    International Nuclear Information System (INIS)

    Gao Yajun

    2007-01-01

    The symmetry structures of two-dimensional heterotic string theory are studied further. A (2d+n)x(2d+n) matrix complex H-potential is constructed and the field equations are extended into a complex matrix formulation. A pair of Hauser-Ernst-type linear systems are established. Based on these linear systems, explicit formulations of new hidden symmetry transformations for the considered theory are given and then these symmetry transformations are verified to constitute infinite-dimensional Lie algebras: the semidirect product of the Kac-Moody o(d,d+n-circumflex) and Virasoro algebras (without center charges). These results demonstrate that the heterotic string theory under consideration possesses more and richer symmetry structures than previously expected

  9. Supersymmetric sigma models and the heterotic string

    International Nuclear Information System (INIS)

    Hull, C.M.; Witten, E.

    1989-01-01

    The authors define the (1 + 1)-dimensional supersymmetry algebra of type (p, q) to be that generated by p right-handed Majorana-Weyl supercharges and q left-handed ones. They construct the non-linear sigma models with supersymmetry of type (1, 0) and (2, 0) and discuss their geometry and their relevance to compactifications of the heterotic superstring. The sigma-model anomalies can be canceled by a mechanism closely related to that used by Green and Schwarz to cancel gravitational and Yang-Mills anomalies for the superstring

  10. Low Energy Supersymmetry from the Heterotic String Landscape

    CERN Document Server

    Lebedev, O; Raby, S; Ramos-Sanchez, S; Ratz, M; Vaudrevange, P K S; Wingerter, A; Lebedev, Oleg; Nilles, Hans-Peter; Raby, Stuart; Ramos-Sanchez, Saul; Ratz, Michael; Vaudrevange, Patrick K. S.; Wingerter, Akin

    2007-01-01

    We study possible correlations between properties of the observable and hidden sectors in heterotic string theory. Specifically, we analyze the case of the Z6-II orbifold compactification which produces a significant number of models with the spectrum of the supersymmetric standard model. We find that requiring realistic features does affect the hidden sector such that hidden sector gauge group factors SU(4) and SO(8) are favoured. In the context of gaugino condensation, this implies low energy supersymmetry breaking.

  11. The crystallographic space groups and Heterotic string theory

    International Nuclear Information System (INIS)

    El Naschie, M.S.

    2009-01-01

    While the 17 planar crystallographic groups were shown to correspond to 17 two and three Stein spaces with a total dimension equal to DimE12=5α-bar o ≅685, the present work reveals that the corresponding 219 three dimensional groups leads to a total dimensionality equal to N o ≅8872 which happens to be the exact total number of massless states of the transfinite version of Heterotic super string spectrum.

  12. Constructing 5d orbifold grand unified theories from heterotic strings

    International Nuclear Information System (INIS)

    Kobayashi, Tatsuo; Raby, Stuart; Zhang Renjie

    2004-01-01

    A three-generation Pati-Salam model is constructed by compactifying the heterotic string on a particular T 6 /Z 6 Abelian symmetric orbifold with two discrete Wilson lines. The compactified space is taken to be the Lie algebra lattice G 2 -bar SU(3)-bar SO(4). When one dimension of the SO(4) lattice is large compared to the string scale, this model reproduces many features of a 5d SO(10) grand unified theory compactified on an S 1 /Z 2 orbifold. (Of course, with two large extra dimensions we can obtain a 6d SO(10) grand unified theory.) We identify the orbifold parities and other ingredients of the orbifold grand unified theories in the string model. Our construction provides a UV completion of orbifold grand unified theories, and gives new insights into both field theoretical and string theoretical constructions

  13. Anomaly, fluxes and (2,0) heterotic-string compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Gillard, Joe; Papadopoulos, George; Tsimpis, Dimitrios [Department of Mathematics, King' s College London, Strand, London WC2R 2LS (United Kingdom)]. E-mail: tsimpis@fy.chalmers.se

    2003-06-01

    We compute the corrections to heterotic-string backgrounds with (2,0) world-sheet supersymmetry, up to two loops in sigma-model perturbation theory. We investigate the conditions for these backgrounds to preserve spacetime supersymmetry and we find that a sufficient requirement for consistency is the applicability of the {partial_derivative} {partial_derivative}-bar-lemma. In particular, we investigate the {alpha}' corrections to (2,0) heterotic-string compactifications and we find that the Calabi-Yau geometry of the internal space is deformed to a hermitean one. We show that at first order in {alpha}', the heterotic anomaly-cancellation mechanism does not induce any lifting of moduli. We explicitly compute the corrections to the conifold and to the U(n)-invariant Calabi-Yau metric at first order in {alpha}'. We also find a generalization of the gauge-field equations, compatible with the Donaldson equations on conformally-balanced hermitean manifolds. (author)

  14. Gravitational threshold corrections in non-supersymmetric heterotic strings

    Directory of Open Access Journals (Sweden)

    Ioannis Florakis

    2017-03-01

    Full Text Available We compute one-loop quantum corrections to gravitational couplings in the effective action of four-dimensional heterotic strings where supersymmetry is spontaneously broken by Scherk–Schwarz fluxes. We show that in both heterotic and type II theories of this class, no moduli dependent corrections to the Planck mass are generated. We explicitly compute the one-loop corrections to the R2 coupling and find that, despite the absence of supersymmetry, its contributions may still be organised into representations of subgroups of the modular group, and admit a universal form, determined uniquely by the multiplicities of the ground states of the theory. Moreover, similarly to the case of gauge couplings, also the gravitational sector may become strongly coupled in models which dynamically induce large volume for the extra dimensions.

  15. Compactifications of heterotic strings on non-Kaehler complex manifolds II

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie; Dasgupta, Keshav; Green, Paul S.; Sharpe, Eric

    2004-01-01

    We continue our study of heterotic compactifications on non-Kaehler complex manifolds with torsion. We give further evidence of the consistency of the six-dimensional manifold presented earlier and discuss the anomaly cancellation and possible supergravity description for a generic non-Kaehler complex manifold using the newly proposed superpotential. The manifolds studied in our earlier papers had zero Euler characteristics. We construct new examples of non-Kaehler complex manifolds with torsion in lower dimensions, that have nonzero Euler characteristics. Some of these examples are constructed from consistent backgrounds in F-theory and therefore are solutions to the string equations of motion. We discuss consistency conditions for compactifications of the heterotic string on smooth non-Kaehler manifolds and illustrate how some results well known for Calabi-Yau compactifications, including counting the number of generations, apply to the non-Kaehler case. We briefly address various issues regarding possible phenomenological applications

  16. One loop tadpole in heterotic string field theory

    Science.gov (United States)

    Erler, Theodore; Konopka, Sebastian; Sachs, Ivo

    2017-11-01

    We compute the off-shell 1-loop tadpole amplitude in heterotic string field theory. With a special choice of cubic vertex, we show that this amplitude can be computed exactly. We obtain explicit and elementary expressions for the Feynman graph decomposition of the moduli space, the local coordinate map at the puncture as a function of the modulus, and the b-ghost insertions needed for the integration measure. Recently developed homotopy algebra methods provide a consistent configuration of picture changing operators. We discuss the consequences of spurious poles for the choice of picture changing operators.

  17. Towards low energy physics from the heterotic string

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, S.N.R.

    2008-06-15

    We investigate orbifold compactifications of the heterotic string, addressing in detail their construction, classification and phenomenological potential. Based on the insight gained from grand unification theories, we develop a successful strategy to search for models resembling the minimal supersymmetric extension of the standard model (MSSM) in Z{sub 6}-II orbifold compactifications. We find about 200 MSSM candidates with the gauge group and the exact spectrum of the MSSM, and supersymmetric vacua below the compactification scale. Among them, there are several models with the following realistic features: R-parity, seesaw suppressed neutrino masses, and intermediate scale of supersymmetry breakdown. (orig.)

  18. Spontaneous symmetry breaking in 4-dimensional heterotic string

    International Nuclear Information System (INIS)

    Maharana, J.

    1989-07-01

    The evolution of a 4-dimensional heterotic string is considered in the background of its massless excitations such as graviton, antisymmetric tensor, gauge fields and scalar bosons. The compactified bosonic coordinates are fermionized. The world-sheet supersymmetry requirement enforces Thirring-like four fermion coupling to the background scalar fields. The non-abelian gauge symmetry is exhibited through the Ward identities of the S-matrix elements. The spontaneous symmetry breaking mechanism is exhibited through the broken Ward identities. An effective 4-dimensional action is constructed and the consequence of spontaneous symmetry breaking is envisaged for the effective action. 19 refs

  19. Exploring the web of heterotic string theories using anomalies

    International Nuclear Information System (INIS)

    Ruehle, Fabian

    2013-07-01

    We investigate how anomalies can be used to infer relations among different descriptions of heterotic string theory. Starting from the observation that the construction mechanism of heterotic orbifold compactifications considered up to now prevents them from being resolved into fully smooth Calabi-Yau compactification manifolds, we use a new mechanism to obtain an orbifold which does not suffer from the aforementioned limitations. We explain in general how to resolve orbifolds into smooth Calabi-Yau using toric geometry and gauged linear sigma models. The latter allow for studying the theory in various other regions of the string moduli space as well, which unveils interesting intermediate geometries. By following anomalies through the different regimes, we can match the orbifold theories to their smooth Calabi-Yau counterparts. In the process, we investigate discrete R and non-R orbifold symmetries and propose a mechanism for studying their fate in other regions of the moduli space. Finally, we introduce a novel anomaly cancelation mechanism in gauged linear sigma models, which manifests itself in target space as a description of compactification geometries with torsion and Neveu-Schwarz five branes.

  20. Exploring the web of heterotic string theories using anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Ruehle, Fabian

    2013-07-15

    We investigate how anomalies can be used to infer relations among different descriptions of heterotic string theory. Starting from the observation that the construction mechanism of heterotic orbifold compactifications considered up to now prevents them from being resolved into fully smooth Calabi-Yau compactification manifolds, we use a new mechanism to obtain an orbifold which does not suffer from the aforementioned limitations. We explain in general how to resolve orbifolds into smooth Calabi-Yau using toric geometry and gauged linear sigma models. The latter allow for studying the theory in various other regions of the string moduli space as well, which unveils interesting intermediate geometries. By following anomalies through the different regimes, we can match the orbifold theories to their smooth Calabi-Yau counterparts. In the process, we investigate discrete R and non-R orbifold symmetries and propose a mechanism for studying their fate in other regions of the moduli space. Finally, we introduce a novel anomaly cancelation mechanism in gauged linear sigma models, which manifests itself in target space as a description of compactification geometries with torsion and Neveu-Schwarz five branes.

  1. Supersymmetric standard model from the heterotic string (II)

    International Nuclear Information System (INIS)

    Buchmueller, W.; Hamaguchi, K.; Tokyo Univ.; Lebedev, O.; Ratz, M.

    2006-06-01

    We describe in detail a Z 6 orbifold compactification of the heterotic E 8 x E 8 string which leads to the (supersymmetric) standard model gauge group and matter content. The quarks and leptons appear as three 16-plets of SO(10), two of which are localized at fixed points with local SO(10) symmetry. The model has supersymmetric vacua without exotics at low energies and is consistent with gauge coupling unification. Supersymmetry can be broken via gaugino condensation in the hidden sector. The model has large vacuum degeneracy. Certain vacua with approximate B-L symmetry have attractive phenomenological features. The top quark Yukawa coupling arises from gauge interactions and is of the order of the gauge couplings. The other Yukawa couplings are suppressed by powers of standard model singlet fields, similarly to the Froggatt-Nielsen mechanism. (Orig.)

  2. Classification of flipped SU(5) heterotic-string vacua

    Energy Technology Data Exchange (ETDEWEB)

    Faraggi, Alon E., E-mail: alon.faraggi@liv.ac.uk [Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom); Rizos, John, E-mail: irizos@uoi.gr [Department of Physics, University of Ioannina, GR45110 Ioannina (Greece); Sonmez, Hasan, E-mail: Hasan.Sonmez@liv.ac.uk [Department of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom)

    2014-09-15

    We extend the classification of free fermionic heterotic-string vacua to models in which the SO(10) GUT symmetry is reduced at the string level to the flipped SU(5) subgroup. In our classification method the set of boundary condition basis vectors is fixed and the enumeration of string vacua is obtained in terms of the Generalised GSO (GGSO) projection coefficients entering the one-loop partition function. We derive algebraic expressions for the GGSO projections for all the physical states appearing in the sectors generated by the set of basis vectors. This enables the programming of the entire spectrum analysis in a computer code. For that purpose we developed two independent codes, based on FORTRAN95 and JAVA, and all results presented are confirmed by the two independent routines. We perform a statistical sampling in the space of 2{sup 44}∼10{sup 13} flipped SU(5) vacua, and scan up to 10{sup 12} GGSO configurations. Contrary to the corresponding Pati–Salam classification results, we do not find exophobic flipped SU(5) vacua with an odd number of generations. We study the structure of exotic states appearing in the three generation models, that additionally contain a viable Higgs spectrum, and demonstrate the existence of models in which all the exotic states are confined by a hidden sector non-Abelian gauge symmetry, as well as models that may admit the racetrack mechanism.

  3. Entropy Spectrum of Black Holes of Heterotic String Theory via Adiabatic Invariance

    Institute of Scientific and Technical Information of China (English)

    Alexis Larra? aga; Luis Cabarique; Manuel Londo? o

    2012-01-01

    Using adiabatic invariance and the Bohr-Sommerfeld quantization rule we investigate the entropy spectroscopy of two black holes of heterotic string theory,the charged GMGHS and the rotating Sen solutions.It is shown that the entropy spectrum is equally spaced in both cases,identically to the spectrum obtained before for Schwarzschild,Reissner-Nordstr?m and Kerr black holes.Since the adiabatic invariance method does not use quasinormal mode analysis,there is no need to impose the small charge or small angular momentum limits and there is no confusion on whether the real part or the imaginary part of the modes is responsible for the entropy spectrum.

  4. Calabi-Yau compactifications of non-supersymmetric heterotic string theory

    International Nuclear Information System (INIS)

    Blaszczyk, Michael; Groot Nibbelink, Stefan

    2015-07-01

    Phenomenological explorations of heterotic strings have conventionally focused primarily on the E 8 x E 8 theory. We consider smooth compactifications of all three ten-dimensional heterotic theories to exhibit the many similarities between the non-supersymmetric SO(16) x SO(16) theory and the related supersymmetric E 8 x E 8 and SO(32) theories. In particular, we exploit these similarities to determine the bosonic and fermionic spectra of Calabi-Yau compactifications with line bundles of the nonsupersymmetric string. We use elements of four-dimensional supersymmetric effective field theory to characterize the non-supersymmetric action at leading order and determine the Green-Schwarz induced axion-couplings. Using these methods we construct a non-supersymmetric Standard Model(SM)-like theory. In addition, we show that it is possible to obtain SM-like models from the standard embedding using at least an order four Wilson line. Finally, we make a proposal of the states that live on five branes in the SO(16) x SO(16) theory and find under certain assumptions the surprising result that anomaly factorization only admits at most a single brane solution.

  5. The Solution Construction of Heterotic Super-Liouville Model

    Science.gov (United States)

    Yang, Zhan-Ying; Zhen, Yi

    2001-12-01

    We investigate the heterotic super-Liouville model on the base of the basic Lie super-algebra Osp(1|2).Using the super extension of Leznov-Saveliev analysis and Drinfeld-Sokolov linear system, we construct the explicit solution of the heterotic super-Liouville system in component form. We also show that the solutions are local and periodic by calculating the exchange relation of the solution. Finally starting from the action of heterotic super-Liouville model, we obtain the conserved current and conserved charge which possessed the BRST properties.

  6. Amplitude relations in heterotic string theory and Einstein-Yang-Mills

    Energy Technology Data Exchange (ETDEWEB)

    Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, D-14476 Potsdam (Germany)

    2016-11-11

    We present all-multiplicity evidence that the tree-level S-matrix of gluons and gravitons in heterotic string theory can be reduced to color-ordered single-trace amplitudes of the gauge multiplet. Explicit amplitude relations are derived for up to three gravitons, up to two color traces and an arbitrary number of gluons in each case. The results are valid to all orders in the inverse string tension α{sup ′} and generalize to the ten-dimensional superamplitudes which preserve 16 supercharges. Their field-theory limit results in an alternative proof of the recently discovered relations between Einstein-Yang-Mills amplitudes and those of pure Yang-Mills theory. Similarities and differences between the integrands of the Cachazo-He-Yuan formulae and the heterotic string are investigated.

  7. AdS strings with torsion: Noncomplex heterotic compactifications

    International Nuclear Information System (INIS)

    Frey, Andrew R.; Lippert, Matthew

    2005-01-01

    Combining the effects of fluxes and gaugino condensation in heterotic supergravity, we use a ten-dimensional approach to find a new class of four-dimensional supersymmetric AdS 4 compactifications on almost-Hermitian manifolds of SU(3) structure. Computation of the torsion allows a classification of the internal geometry, which for a particular combination of fluxes and condensate, is nearly Kaehler. We argue that all moduli are fixed, and we show that the Kaehler potential and superpotential proposed in the literature yield the correct AdS 4 radius. In the nearly Kaehler case, we are able to solve the H Bianchi identity using a nonstandard embedding. Finally, we point out subtleties in deriving the effective superpotential and understanding the heterotic supergravity in the presence of a gaugino condensate

  8. Thermodynamical aspect of black hole solutions in heteric string theory

    CERN Document Server

    Fujisaki, H

    2003-01-01

    Thermodynamical properties of charged rotating dilatonic black holes are discussed on the basis of the general solution of Sen in the heterotic string theory compactified on a six dimensional torus. The most probable microcanonical configuration of black holes is then described in the single-massive-mode dominance scenario.

  9. Gauge coupling unification in heterotic string models with gauge mediated supersymmetry breaking

    International Nuclear Information System (INIS)

    Anandakrishnan, Archana; Raby, Stuart

    2011-01-01

    We calculate the weak scale minimal supersymmetric standard model spectrum starting from a heterotic string theory compactified on an anisotropic orbifold. Supersymmetry breaking is mediated by vectorlike exotics that arise naturally in heterotic string theories. The messengers that mediate supersymmetry breaking come in incomplete grand unified theory (GUT) multiplets and give rise to nonuniversal gaugino masses at the GUT scale. Models with nonuniversal gaugino masses at the GUT scale have the attractive feature of allowing for precision gauge coupling unification at the GUT scale with negligible contributions from threshold corrections near the unification scale. The unique features of this minimally supersymmetric standard model spectrum are light gluinos and also large mass differences between the lightest and the next-to-lightest neutralinos and charginos which could lead to interesting signatures at the colliders.

  10. Field redefinitions and Chern-Simons terms in the heterotic string

    International Nuclear Information System (INIS)

    Bern, Z.; Shimada, T.

    1987-07-01

    Field redefinitions in the low energy effective action of the heterotic string are discussed. A field redefinition is constructed which generates the local counterterm that transforms the Lorentz into the gravitational form of the anomaly. We also discuss the field redefinition which torsionizes the Lorentz Chern-Simons term and its relation to an amplitude matching study of the compatibility of torsion with the Gauss-Bonnet combination. (orig.)

  11. Background constraints in the infinite tension limit of the heterotic string

    Czech Academy of Sciences Publication Activity Database

    Azevedo, T.; Lipinski Jusinskas, Renann

    2016-01-01

    Roč. 2016, č. 8 (2016), s. 1-23, č. článku 133. ISSN 1029-8479 R&D Projects: GA ČR GBP201/12/G028 Institutional support: RVO:68378271 Keywords : conformal field models in string theory * superstrings and heterotic strings Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 6.063, year: 2016

  12. D-term Spectroscopy in Realistic Heterotic-String Models

    CERN Document Server

    Dedes, Athanasios

    2000-01-01

    The emergence of free fermionic string models with solely the MSSM charged spectrum below the string scale provides further evidence to the assertion that the true string vacuum is connected to the Z_2 x Z_2 orbifold in the vicinity of the free fermionic point in the Narain moduli space. An important property of the Z_2 x Z_2 orbifold is the cyclic permutation symmetry between the three twisted sectors. If preserved in the three generations models the cyclic permutation symmetry results in a family universal anomalous U(1)_A, which is instrumental in explaining squark degeneracy, provided that the dominant component of supersymmetry breaking arises from the U(1)_A D-term. Interestingly, the contribution of the family--universal D_A-term to the squark masses may be intra-family non-universal, and may differ from the usual (universal) boundary conditions assumed in the MSSM. We contemplate how D_A--term spectroscopy may be instrumental in studying superstring models irrespective of our ignorance of the details ...

  13. Non-supersymmetric flux compactifications of heterotic string- and M-theory

    Energy Technology Data Exchange (ETDEWEB)

    Held, Johannes Georg Joseph

    2012-05-08

    This dissertation is concerned with non-supersymmetric vacua of string theory in the supergravity (SUGRA) approach. This approach is the effective description of string theory at low energies. The concrete field of research that is treated here is heterotic E{sub 8} x E{sub 8} string theory at weak and at strong coupling, respectively. In the strong coupling limit the theory is described by eleven-dimensional SUGRA with two ten-dimensional boundaries (heterotic M-Theory). The transition to the weak coupling limit is governed by the restricted space dimension, whose length tends to zero for weak coupling such that the two boundaries get identified with each other. The resulting theory is ten-dimensional E{sub 8} x E{sub 8} SUGRA. In the context of this heterotic SUGRA, at first six of the former nine space-dimensions are compactified, and then, in the presence of non-vanishing background flux, conditions for unbroken supersymmetry (SUSY) in four space-time dimensions are analyzed. Afterwards, a violation of one of the necessary SUSY conditions is allowed. An essential ingredient, necessary for this to work, is the presence of flux. This kind of SUSY-breaking leads to severe constraints on the compact six-dimensional manifold, which can be satisfied by fiber bundles with two-dimensional fiber and four-dimensional base. In simple examples one can stabilize the expectation value of the dilaton as well as the volume of the fiber, whereas the volume of the base remains undetermined. Furthermore, the effect of a fermionic condensate is analyzed. The expected additional SUSY-breaking can be observed, and it is shown that the breaking induced by the flux can not be canceled by the contributions from the condensate. The end of this thesis is concerned with the discussion of the strong coupling limit of the previously found examples. To analyze this, it is necessary to rewrite the action of heterotic M-theory as a sum of quadratic terms, which vanish once SUSY is imposed

  14. Torsional heterotic geometries

    International Nuclear Information System (INIS)

    Becker, Katrin; Sethi, Savdeep

    2009-01-01

    We construct new examples of torsional heterotic backgrounds using duality with orientifold flux compactifications. We explain how duality provides a perturbative solution to the type I/heterotic string Bianchi identity. The choice of connection used in the Bianchi identity plays an important role in the construction. We propose the existence of a much larger landscape of compact torsional geometries using string duality. Finally, we present some quantum exact metrics that correspond to NS5-branes placed on an elliptic space. These metrics describe how torus isometries are broken by NS flux.

  15. Dualities in five dimensions and charged string solutions

    International Nuclear Information System (INIS)

    Kar, S.; Maharana, J.

    1996-01-01

    We consider an eleven dimensional supergravity compactified on K3 x T 2 and show that the resulting five dimensional theory has identical massless states as that of a heterotic string compactified on a specific five torus T 5 . The strong-weak coupling duality of the five dimensional theory is argued to represent a ten dimensional Type IIA string compactified on K3 x S 1 , supporting the conjecture of string-string duality in six dimensions. In this perspective, we present a magnetically charged solution of the low energy heterotic string effective action in five dimensions with a charge defined on a three sphere S 3 due to the two form potential. We use the Poincare duality to replace the antisymmetric two form with a gauge field in the effective action and obtain a string solution with charge on a two sphere S 2 instead of that on a three sphere S 3 in the five dimensional spacetime. We note that the string-particle duality is accompanied by a change of topology from S 3 to S 2 and vice versa. (orig.)

  16. Anomaly cancellation in effective supergravity theories from the heterotic string: Two simple examples

    Directory of Open Access Journals (Sweden)

    Mary K. Gaillard

    2018-02-01

    Full Text Available We use Pauli–Villars regularization to evaluate the conformal and chiral anomalies in the effective field theories from Z3 and Z7 compactifications of the heterotic string without Wilson lines. We show that parameters for Pauli–Villars chiral multiplets can be chosen in such a way that the anomaly is universal in the sense that its coefficient depends only on a single holomorphic function of the three diagonal moduli. It is therefore possible to cancel the anomaly by a generalization of the four-dimensional Green–Schwarz mechanism. In particular we are able to reproduce the results of a string calculation of the four-dimensional chiral anomaly for these two models.

  17. Anomaly cancellation in effective supergravity theories from the heterotic string: Two simple examples

    Science.gov (United States)

    Gaillard, Mary K.; Leedom, Jacob

    2018-02-01

    We use Pauli-Villars regularization to evaluate the conformal and chiral anomalies in the effective field theories from Z3 and Z7 compactifications of the heterotic string without Wilson lines. We show that parameters for Pauli-Villars chiral multiplets can be chosen in such a way that the anomaly is universal in the sense that its coefficient depends only on a single holomorphic function of the three diagonal moduli. It is therefore possible to cancel the anomaly by a generalization of the four-dimensional Green-Schwarz mechanism. In particular we are able to reproduce the results of a string calculation of the four-dimensional chiral anomaly for these two models.

  18. Charged string solutions with dilaton and modulus fields

    CERN Document Server

    Cvetic, M

    1994-01-01

    We find charged, abelian, spherically symmetric solutions (in flat space-time) corresponding to the effective action of $D=4$ heterotic string theory with scale-dependent dilaton $\\p$ and modulus $\\vp$ fields. We take into account perturbative (genus-one), moduli-dependent `threshold' corrections to the coupling function $f(\\p,\\vp)$ in the gauge field kinetic term $f(\\p,\\vp) F^2_{\\m\

  19. Vanishing of the vacuum amplitude of heterotic string compactified on a tensor product of N=2 superconformal models

    International Nuclear Information System (INIS)

    Kei Ito.

    1988-07-01

    The vacuum amplitude of heterotic string compactified on a tensor product of nine copies of c=1, N=2 superconformal models is shown to vanish due to a generalized Riemann's theta identity associated with the 12x12 matrix identity t BB=6 2 I 12 , identity B ij =-5(i=j), 1(i≠j). (author). 4 refs

  20. Flipped SU(5) from manifold compactification of the ten-dimensional heterotic string

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, B.A.; Ellis, J.; Hagelin, J.S.; Ticciati, R.; Nanopoulos, D.V.

    1987-11-19

    We show that a recently proposed flipped SU(5) x U(1) GUT cannot be obtained from a conventional SO(10) GUT, nor from the heterotic string by Hosotani gauge symmetry breaking of E/sub 6/ on a manifold with (2,2) world-sheet supersymmetry. It can in principle be obtained by Hosotani gauge symmetry breaking of SO(10) on a manifold with (1,2) world-sheet supersymmetry. We identify the topological conditions under which the required chiral matter generations, Higgs multiplets, and gauge singlet fields can be light. In particular we show that non-perturbative world-sheet instanton effects neither destabilize the manifold nor give masses to the gauge singlets. The required Yukawa couplings are not forbidden by any known selection rules.

  1. Coset space compactification of the field theory limit of a heterotic string

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.; Helayel-Neto, J.A.

    1986-07-01

    The D = 10 - E/sub 8/xE/sub 8/ field theory limit of the heterotic string is compactified on the non-symmetric coset space Sp(4)/SU(2) xU(1) that is known in the limit of decoupled gravity to give three standard fermion generations, with SU(5)xSU(3)sub(F)xU(1)sub(F) as a gauge group in D = 4. Allowing for non-vanishing fermion bilinear condensates, and assuming the conventional form of the supersymmetry transformations, the presence of a family of N = 1 supersymmetric background field configurations is proved. This requires the non-compact space to be flat: (Minkowski)/sup 4/, while the 3-form Hsub(MNP) is non-vanishing and proportional to the torsion on the internal manifold. All equations of motion, including that of the dilation, are satisfied.

  2. A coset space compactification of the field theory limit of a heterotic string

    International Nuclear Information System (INIS)

    Foda, O.; Helayel-Neto, J.A.

    1986-01-01

    The D = 10 - E 8 xE 8 field theory limit of the heterotic string is compactified on the non-symmetric coset space Sp(4)/SU(2) xU(1) that is known in the limit of decoupled gravity to give three standard fermion generations, with SU(5)xSU(3)sub(F)xU(1)sub(F) as a gauge group in D = 4. Allowing for non-vanishing fermion bilinear condensates, and assuming the conventional form of the supersymmetry transformations, the presence of a family of N = 1 supersymmetric background field configurations is proved. This requires the non-compact space to be flat: (Minkowski) 4 , while the 3-form Hsub(MNP) is non-vanishing and proportional to the torsion on the internal manifold. All equations of motion, including that of the dilation, are satisfied. (author)

  3. A coset-space compactification of the field-theory limit of a heterotic string

    International Nuclear Information System (INIS)

    Foda, O.; Helayel-Neto, J.A.

    1985-06-01

    The D=10-E 8 xE 8 field-theory limit of the heterotic string is compactified on the non-symmetric coset-space Sp(4)/SU(2)xU(1), that is known - in the limit of decoupled gravity - to give 3 standard fermion generations, with SU(5)xSU(3)sub(F)xU(1)sub(F) as a gauge group in D=4. Allowing for non-vanishing fermion-bilinear condensates, and assuming the conventional form of the supersymmetry transformations, we prove the presence of a family of N=1 supersymmetric background field configurations. This requires the non-compact space to be flat: (Minkowski) 4 , while the 3-form Hsub(MNP) is non-vanishing, and proportional to the torsion on the internal manifold. All equations of motion - including that of the dilaton - are satisfied. (author)

  4. α'-Corrections to extremal dyonic black holes in heterotic string theory

    International Nuclear Information System (INIS)

    Sahoo, Bindusar; Sen, Ashoke

    2007-01-01

    We explicitly compute the entropy of an extremal dyonic black hole in heterotic string theory compactified on T 6 or K3 x T 2 by taking into account all the tree level four derivative corrections to the low energy effective action. For supersymmetric black holes the result agrees with the answer obtained earlier 1) by including only the Gauss-Bonnet corrections to the effective action 2) by including all terms related to the curvature squared terms via space-time supersymmetry transformation, and 3) by using general arguments based on the assumption of AdS 3 near horizon geometry and space-time supersymmetry. For non-supersymmetric extremal black holes the result agrees with the one based on the assumption of AdS 3 near horizon geometry and space-time supersymmetry of the underlying theory

  5. Toward the realistic three-generation model in the (2,0) heterotic string compactification

    International Nuclear Information System (INIS)

    Asatryan, H.M.; Murayama, A.

    1992-01-01

    In this paper, the three generation models with SUSY SO(10) or SU(5) GUTs derived from the (2,0) compactification of E 8 x E' 8 heterotic string, the massless matter field spectra at the GUT scale M X and the breaking directions of GUT symmetries are discussed. A pseudo-left-right symmetric Pati-Salam model is naturally deduced in the SUSY SO(10) GUT and shown to have an interesting property, M x ≅ M P1 , M R ≅ 10 10 GeV and M S ( the scale of superpartner masses) ≅ 10 4 GeV, as a result of the renormalization group equation analysis using the new precise LEP data

  6. Classical and quantum aspects of BPS black holes in N=2,D=4 heterotic string compactifications

    International Nuclear Information System (INIS)

    Rey, S.-J.

    1997-01-01

    We study classical and quantum aspects of D=4, N=2 BPS black holes for T 2 compactification of D=6, N=1 heterotic string vacua. We extend dynamical relaxation phenomena of moduli fields to a background consisting of a BPS soliton or a black hole and provide a simpler but more general derivation of the Ferrara-Kallosh extremized black hole mass and entropy. We study quantum effects to the BPS black hole mass spectra and to their dynamical relaxation. We show that, despite non-renormalizability of string effective supergravity, the quantum effect modifies BPS mass spectra only through coupling constant and moduli field renormalizations. Based on target-space duality, we establish a perturbative non-renormalization theorem and obtain the exact BPS black hole mass and entropy in terms of the renormalized string loop-counting parameter and renormalized moduli fields. We show that a similar conclusion holds, in the large T 2 limit, for leading non-perturbative correction. We finally discuss implications to type-I and type-IIA Calabi-Yau black holes. (orig.)

  7. (MS)SM-like models on smooth Calabi-Yau manifolds from all three heterotic string theories

    International Nuclear Information System (INIS)

    Groot Nibbelink, Stefan

    2015-09-01

    We perform model searches on smooth Calabi-Yau compactifications for both the supersymmetric E 8 x E 8 and SO(32) as well as for the non-supersymmetric SO(16) x SO(16) heterotic strings simultaneously. We consider line bundle backgrounds on both favorable CICYs with relatively small h 11 and the Schoen manifold. Using Gram matrices we systematically analyze the combined consequences of the Bianchi identities and the tree-level Donaldson-Uhlenbeck-Yau equations inside the Kaehler cone. In order to evaluate the model building potential of the three heterotic theories on the various geometries, we perform computer-aided scans. We have generated a large number of GUT-like models (up to over a few hundred thousand on the various geometries for the three heterotic theories) which become (MS)SM-like upon using a freely acting Wilson line. For all three heterotic theories we present tables and figures summarizing the potentially phenomenologically interesting models which were obtained during our model scans.

  8. N=2 heterotic string compactifications on orbifolds of K3×T{sup 2}

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyaya, Aradhita; David, Justin R. [Centre for High Energy Physics, Indian Institute of Science,C.V. Raman Avenue, Bangalore 560012 (India)

    2017-01-10

    We study N=2 compactifications of E{sub 8}×E{sub 8} heterotic string theory on orbifolds of K3×T{sup 2} by g{sup ′} which acts as an ℤ{sub N} automorphism of K3 together with a 1/N shift on a circle of T{sup 2}. The orbifold action g{sup ′} corresponds to the 26 conjugacy classes of the Mathieu group M{sub 24}. We show that for the standard embedding the new supersymmetric index for these compactifications can always be decomposed into the elliptic genus of K3 twisted by g{sup ′}. The difference in one-loop corrections to the gauge couplings are captured by automorphic forms obtained by the theta lifts of the elliptic genus of K3 twisted by g{sup ′}. We work out in detail the case for which g{sup ′} belongs to the equivalence class 2B. We then investigate all the non-standard embeddings for K3 realized as a T{sup 4}/ℤ{sub ν} orbifold with ν=2,4 and g{sup ′} the 2A involution. We show that for non-standard embeddings the new supersymmetric index as well as the difference in one-loop corrections to the gauge couplings are completely characterized by the instanton numbers of the embeddings together with the difference in number of hypermultiplets and vector multiplets in the spectrum.

  9. Automated Systematic Generation and Exploration of Flat Direction Phenomenology in Free Fermionic Heterotic String Theory

    Science.gov (United States)

    Greenwald, Jared

    Any good physical theory must resolve current experimental data as well as offer predictions for potential searches in the future. The Standard Model of particle physics, Grand Unied Theories, Minimal Supersymmetric Models and Supergravity are all attempts to provide such a framework. However, they all lack the ability to predict many of the parameters that each of the theories utilize. String theory may yield a solution to this naturalness (or self-predictiveness) problem as well as offer a unifed theory of gravity. Studies in particle physics phenomenology based on perturbative low energy analysis of various string theories can help determine the candidacy of such models. After a review of principles and problems leading up to our current understanding of the universe, we will discuss some of the best particle physics model building techniques that have been developed using string theory. This will culminate in the introduction of a novel approach to a computational, systematic analysis of the various physical phenomena that arise from these string models. We focus on the necessary assumptions, complexity and open questions that arise while making a fully-automated at direction analysis program.

  10. Boson-fermion mass splittings in four-dimensional heterotic string models with anomalous U(1) gauge groups

    International Nuclear Information System (INIS)

    Yamaguchi, Masahiro; Yamamoto, Hisashi; Onogi, Tetsuya

    1989-01-01

    In four-dimensional heterotic string models with anomalous U(1) gauge groups, space-time supersymmetry (SUSY) breaks down spontaneously at one loop. In this paper, the Ward-Takahashi identity of broken SUSY in one-loop two-point amplitudes is investigated in all generalities. The boson-fermion mass splitting of any supersymmetric pair in an arbitrary model is proportional to the product of the D-term expectation value (the sum of (chirality)x(U(1) charge) of massless fermions in the model) and the U(1) charge of the external particle. In order to give a better understanding of the results, we present some examples of the mass splittings in a simple Z 3 orbifold model. (orig.)

  11. Exact solutions and singularities in string theory

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Tseytlin, A.A.

    1994-01-01

    We construct two new classes of exact solutions to string theory which are not of the standard plane wave of gauged WZW type. Many of these solutions have curvature singularities. The first class includes the fundamental string solution, for which the string coupling vanishes near the singularity. This suggests that the singularity may not be removed by quantum corrections. The second class consists of hybrids of plane wave and gauged WZW solutions. We discuss a four-dimensional example in detail

  12. Extremal black holes as exact string solutions

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Tseytlin, A.A.

    1994-01-01

    We show that the leading order solution describing an extremal electrically charged black hole in string theory is, in fact, an exact solution to all orders in α' when interpreted in a Kaluza-Klein fashion. This follows from the observation that it can be obtained via dimensional reduction from a five-dimensional background which is proved to be an exact string solution

  13. LHC di-photon excess and gauge coupling unification in extra Z{sup '} heterotic-string derived models

    Energy Technology Data Exchange (ETDEWEB)

    Ashfaque, J. [University of Liverpool, Department of Mathematical Sciences, Liverpool (United Kingdom); Delle Rose, L. [University of Southampton, School of Physics and Astronomy, Southampton (United Kingdom); Faraggi, A.E. [Rutherford Appleton Laboratory, Department of Particle Physics, Chilton, Didcot (United Kingdom); Marzo, C. [Universita del Salento, Dipartimento di Matematica e Fisica ' ' Ennio De Giorgi' ' , Lecce (Italy); INFN, Lecce (Italy)

    2016-10-15

    A di-photon excess at the LHC can be explained as a Standard Model singlet that is produced and decays by heavy vector-like colour triplets and electroweak doublets in one-loop diagrams. The characteristics of the required spectrum are well motivated in heterotic-string constructions that allow for a light Z{sup '}. Anomaly cancellation of the U(1){sub Z'} symmetry requires the existence of the Standard Model singlet and vector-like states in the vicinity of the U(1){sub Z'} breaking scale. In this paper we show that the agreement with the gauge coupling data at one-loop is identical to the case of the Minimal Supersymmetric Standard Model, owing to cancellations between the additional states. We further show that effects arising from heavy thresholds may push the supersymmetric spectrum beyond the reach of the LHC, while maintaining the agreement with the gauge coupling data. We show that the string-inspired model can indeed produce an observable signal and discuss the feasibility of obtaining viable scalar mass spectrum. (orig.)

  14. Cosmological string solutions by dimensional reduction

    International Nuclear Information System (INIS)

    Behrndt, K.; Foerste, S.

    1993-12-01

    We obtain cosmological four dimensional solutions of the low energy effective string theory by reducing a five dimensional black hole, and black hole-de Sitter solution of the Einstein gravity down to four dimensions. The appearance of a cosmological constant in the five dimensional Einstein-Hilbert produces a special dilaton potential in the four dimensional effective string action. Cosmological scenarios implement by our solutions are discussed

  15. Heterotic brane world

    International Nuclear Information System (INIS)

    Nilles, H.-P.

    2004-01-01

    Heterotic E 8 x E 8 string theory is a promising source of grand unified model building. It can accommodate the successful aspects of grand unification while avoiding problems like doublet-triplet splitting in the Higgs sector and fast proton decay. We exploit the geometrical properties of the theory as a guideline for realistic model building. (author)

  16. Cosmic strings: A problem or a solution?

    International Nuclear Information System (INIS)

    Bennett, D.P.; Bouchet, F.R.

    1987-10-01

    The most fundamental issue in the theory of cosmic strings is addressed by means of Numerical Simulations: the existence of a scaling solution. The resolution of this question will determine whether cosmic strings can form the basis of an attractive theory of galaxy formation or prove to be a cosmological disaster like magnetic monopoles or domain walls. After a brief discussion of our numerical technique, results are presented which, though still preliminary, offer the best support to date of this scaling hypothesis. 6 refs., 2 figs

  17. General solution of string inspired nonlinear equations

    International Nuclear Information System (INIS)

    Bandos, I.A.; Ivanov, E.; Kapustnikov, A.A.; Ulanov, S.A.

    1998-07-01

    We present the general solution of the system of coupled nonlinear equations describing dynamics of D-dimensional bosonic string in the geometric (or embedding) approach. The solution is parametrized in terms of two sets of the left- and right-moving Lorentz harmonic variables providing a special coset space realization of the product of two (D-2) dimensional spheres S D-2 = SO(1,D-1)/SO(1,1)xSO(D-2) contained in K D-2 . (author)

  18. String field theory solution for any open string background

    Czech Academy of Sciences Publication Activity Database

    Erler, T.; Maccaferri, Carlo

    2014-01-01

    Roč. 10, Oct (2014), 1-37 ISSN 1029-8479 R&D Projects: GA ČR GBP201/12/G028 Institutional support: RVO:68378271 Keywords : tachyon condensation * string field theory * conformal field models in string theory * bosonic strings Subject RIV: BE - Theoretical Physics Impact factor: 6.111, year: 2014

  19. Non-static vacuum strings: exterior and interior solutions

    International Nuclear Information System (INIS)

    Stein-Schabes, J.A.

    1986-01-01

    New non-static cylindrically symmetric solutions of Einsteins's equations are presented. Some of these solutions represent string-like objects. An exterior vacuum solution is matched to a non-vacuum interior solution for different forms of the energy-momentum tensor. They generalize the standard static string. 12 refs

  20. Heterotic Non-Kähler Geometries via Polystable Bundles on Calabi-Yau Threefolds

    DEFF Research Database (Denmark)

    Andreas, Bjorn; Garcia Fernandez, Mario

    2012-01-01

    In arXiv:1008.1018 it is shown that a given stable vector bundle V on a Calabi-Yau threefold X which satisfies c_2(X) = c_2(V ) can be deformed to a solution of the Strominger system and the equations of motion of heterotic string theory. In this note we extend this result to the polystable case...

  1. Analytic study of nonperturbative solutions in open string field theory

    International Nuclear Information System (INIS)

    Bars, I.; Kishimoto, I.; Matsuo, Y.

    2003-01-01

    We propose an analytic framework to study the nonperturbative solutions of Witten's open string field theory. The method is based on the Moyal star formulation where the kinetic term can be split into two parts. The first one describes the spectrum of two identical half strings which are independent from each other. The second one, which we call midpoint correction, shifts the half string spectrum to that of the standard open string. We show that the nonlinear equation of motion of string field theory is exactly solvable at zeroth order in the midpoint correction. An infinite number of solutions are classified in terms of projection operators. Among them, there exists only one stable solution which is identical to the standard butterfly state. We include the effect of the midpoint correction around each exact zeroth order solution as a perturbation expansion which can be formally summed to the complete exact solution

  2. Some exact solutions of magnetized viscous model in string ...

    Indian Academy of Sciences (India)

    Recently, the string cosmology has received considerable attention in the ... require a quantum theory of gravity, for which string theory seems to be the most promis- ..... where d2 is a constant of integration, which is taken as unity without the loss of ..... The solutions present interesting features in the presence of vis-.

  3. Conformal symmetry and string theories

    International Nuclear Information System (INIS)

    Kumar, A.

    1987-01-01

    This thesis is devoted to the study of various aspects of the 2-dimensional conformal field theory and its applications to strings. We make a short review of the conformal field theory and its supersymmetric extension, called superconformal field theory. We present an elegant superspace formulation of these theories and solve the condition for the closure of the superconformal algebra. The we go on to classify the superconformal field theories according to these solutions. We prove that N ≥ 5 superconformal algebra, with N being the number of supersymmetries, does not have central charge. We find the primary representations of all the interesting superconformal algebra. We study the quantization of the superconformal theories and derive the constraints on the central charge of the algebra that has to be satisfied for a consistent quantum theory. This quantization process also determines the ground state energy of the system and the spectrum of the model. We study the global aspects of the conformal symmetry and its role in the construction of consistent heterotic string theories. We prove the uniqueness of heterotic superstring theories in 10 dimensions in the fermionic constructions. We show how the vertex operators are closely associated with the primary field representation of the conformal algebra. We utilize these vertex operator constructions to obtain tree amplitudes in the 10-dimensional heterotic string theory. We show by explicit calculation at the 3-point level that the scattering amplitudes derived from the heterotic superstring are same as the ones obtained from 10-dimensional supergravity theories

  4. Sv-map between type I and heterotic sigma models

    Science.gov (United States)

    Fan, Wei; Fotopoulos, A.; Stieberger, S.; Taylor, T. R.

    2018-05-01

    The scattering amplitudes of gauge bosons in heterotic and open superstring theories are related by the single-valued projection which yields heterotic amplitudes by selecting a subset of multiple zeta value coefficients in the α‧ (string tension parameter) expansion of open string amplitudes. In the present work, we argue that this relation holds also at the level of low-energy expansions (or individual Feynman diagrams) of the respective effective actions, by investigating the beta functions of two-dimensional sigma models describing world-sheets of open and heterotic strings. We analyze the sigma model Feynman diagrams generating identical effective action terms in both theories and show that the heterotic coefficients are given by the single-valued projection of the open ones. The single-valued projection appears as a result of summing over all radial orderings of heterotic vertices on the complex plane representing string world-sheet.

  5. Baryon string model. II. Special solutions of classical three-string equations of motion

    International Nuclear Information System (INIS)

    Klimenko, S.V.; Kochin, V.N.; Plyushchai, M.S.; Pron'ko, G.P.

    1986-01-01

    The authors consider special solutions of the classical threestring equations of motion. The basic results needed for construction and analysis of the special solutions are examined. The authors consider very simple solutions in which the three-string node moves with the velocity of light. Singlemode solutions are studied. The graphical packet Atom is used to study and visualize the string dynamics. A new procedure was developed within the packet for graphical representation of many parameter functions. The distinctive feature of these procedures is the large class of functions (including explicit, implicit, and parametric functions) that can be represented by means of parametric, coordinate, and functional isolines

  6. Heterotic M2-branes

    Directory of Open Access Journals (Sweden)

    Neil Lambert

    2015-10-01

    Full Text Available We construct the action for N M2-branes on S1/Z2. The resulting theory has a gauge anomaly but this can be cancelled if the two fixed point planes each support 8 chiral Fermions in the fundamental of U(N. Taking the low energy limit leads to the worldsheet theory of N free heterotic strings whose quantization induces an E8 spacetime gauge symmetry on each fixed point plane. Thus this paper presents a non-abelian worldvolume analogue of the classic Hořava–Witten analysis.

  7. Evidence for a scaling solution in cosmic-string evolution

    International Nuclear Information System (INIS)

    Bennett, D.P.; Bouchet, F.R.

    1988-01-01

    We study, by means of numerical simulations, the most fundamental issue of cosmic-string evolution: the existence of a scaling solution. We find strong evidence that a scaling solution does indeed exist. This justifies the main assumption on which the cosmic-string theories of galaxy formation are based. Our main conclusion coincides with that of Albrecht and Turok in previous work, but our results are not consistent with theirs. In fact, our results indicate that the details of string evolution are very different from the standard dogma

  8. Cosmological solutions in string theory with dilaton self interaction potential

    International Nuclear Information System (INIS)

    Mora, C.; Pimentel, L.O.

    2003-01-01

    In this work we present homogeneous and isotropic cosmological solutions for the low energy limit of string theory with a self interacting potential for the scalar field. For a potential that is a linear combination of two exponential, a family of exact solutions are found for the different spatial curvatures. Among this family a non singular accelerating solution for positive curvature is singled out and the violation of the energy conditions for that solution is studied, and also its astrophysical consequences. The string coupling for this solution is finite. (Author)

  9. No Strings Attached: Open Source Solutions

    Science.gov (United States)

    Fredricks, Kathy

    2009-01-01

    Imagine downloading a new software application and not having to worry about licensing, finding dollars in the budget, or incurring additional maintenance costs. Imagine finding a Web design tool in the public domain--free for use. Imagine major universities that provide online courses with no strings attached. Imagine online textbooks without a…

  10. A nonperturbative solution of D=1 string theory

    International Nuclear Information System (INIS)

    Gross, D.J.; Miljkovic, N.

    1990-01-01

    We derive a nonperturbative solution of D=1 string theory, based on a double scaling limit of the one dimensional random matrix model. We derive an exact expression for the partition function in terms of the string coupling constant. The weak coupling expansion suffers from infrared divergences, which we attribute to massless tadpoles. The continuum limit seems to be well defined, however, in a strong coupling expansion. This could correspond to a different stable nonperturbative vacuum. (orig.)

  11. Heterotic moduli stabilization

    International Nuclear Information System (INIS)

    Cicoli, M.; De Alwis, S.; Colorado Univ., Boulder, CO; Westphal, A.

    2013-04-01

    We perform a systematic analysis of moduli stabilization for weakly coupled heterotic string theory compactified on smooth Calabi-Yau three-folds. We focus on both supersymmetric and supersymmetry breaking vacua of generic (0,2) compactifications obtained by minimising the total (F+D)-term scalar potential. After reviewing how to stabilise all the geometric moduli in a supersymmetric way by including fractional fluxes, non-perturbative and threshold effects, we show that the inclusion of α' corrections leads to new de Sitter or nearly Minkowski vacua which break supersymmetry spontaneously. The minimum lies at moderately large volumes of all the geometric moduli, at perturbative values of the string coupling and at the right phenomenological value of the GUT gauge coupling. However the structure of the heterotic 3-form flux used for complex structure moduli stabilization does not contain enough freedom to tune the superpotential. This results in the generic prediction of high-scale supersymmetry breaking around the GUT scale. We finally provide a dynamical derivation of anisotropic compactifications with stabilized moduli which allow for perturbative gauge coupling unification around 10 16 GeV.

  12. Heterotic moduli stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Cicoli, M. [Bologna Univ. (Italy). Dipt. Fisica ed Astronomia; INFN, Bologna (Italy); Adbus Salam ICTP, Trieste (Italy); De Alwis, S. [Adbus Salam ICTP, Trieste (Italy); Colorado Univ., Boulder, CO (United States). UCB 390 Physics Dept.; Westphal, A. [DESY Hamburg (Germany). Theory Group

    2013-04-15

    We perform a systematic analysis of moduli stabilization for weakly coupled heterotic string theory compactified on smooth Calabi-Yau three-folds. We focus on both supersymmetric and supersymmetry breaking vacua of generic (0,2) compactifications obtained by minimising the total (F+D)-term scalar potential. After reviewing how to stabilise all the geometric moduli in a supersymmetric way by including fractional fluxes, non-perturbative and threshold effects, we show that the inclusion of {alpha}' corrections leads to new de Sitter or nearly Minkowski vacua which break supersymmetry spontaneously. The minimum lies at moderately large volumes of all the geometric moduli, at perturbative values of the string coupling and at the right phenomenological value of the GUT gauge coupling. However the structure of the heterotic 3-form flux used for complex structure moduli stabilization does not contain enough freedom to tune the superpotential. This results in the generic prediction of high-scale supersymmetry breaking around the GUT scale. We finally provide a dynamical derivation of anisotropic compactifications with stabilized moduli which allow for perturbative gauge coupling unification around 10{sup 16} GeV.

  13. Non-Perturbative Formulation of Time-Dependent String Solutions

    CERN Document Server

    Alexandre, J; Mavromatos, Nikolaos E; Alexandre, Jean; Ellis, John; Mavromatos, Nikolaos E.

    2006-01-01

    We formulate here a new world-sheet renormalization-group technique for the bosonic string, which is non-perturbative in the Regge slope alpha' and based on a functional method for controlling the quantum fluctuations, whose magnitudes are scaled by the value of alpha'. Using this technique we exhibit, in addition to the well-known linear-dilaton cosmology, a new, non-perturbative time-dependent background solution. Using the reparametrization invariance of the string S-matrix, we demonstrate that this solution is conformally invariant to alpha', and we give a heuristic inductive argument that conformal invariance can be maintained to all orders in alpha'. This new time-dependent string solution may be applicable to primordial cosmology or to the exit from linear-dilaton cosmology at large times.

  14. Nonperturbative flipped SU(5) vacua in heterotic M-theory

    Energy Technology Data Exchange (ETDEWEB)

    Faraggi, Alon E. E-mail: faraggi@thphys.ox.ac.uk; Garavuso, Richard E-mail: garavuso@thphys.ox.ac.uk; Isidro, Jose M. E-mail: isidro@thphys.ox.ac.uk

    2002-10-07

    The evidence for neutrino masses in atmospheric and solar neutrino experiments provides further support for the embedding of the Standard Model fermions in the chiral 16 SO(10) representation. Such an embedding is afforded by the realistic free fermionic heterotic-string models. In this paper we advance the study of these string models toward a nonperturbative analysis by generalizing the work of Donagi, Pantev, Ovrut and Waldram from the case of G=SU(2n+1) to G=SU(2n) stable holomorphic vector bundles on elliptically fibered Calabi-Yau manifolds with fundamental group Z{sub 2}. We demonstrate existence of G=SU(4) solutions with three generations and SO(10) observable gauge group over Hirzebruch base surface, whereas we show that certain classes of del Pezzo base surface do not admit such solutions. The SO(10) symmetry is broken to SU(5)xU(1) by a Wilson line. The overlap with the realistic free fermionic heterotic-string models is discussed.

  15. Hyperbolic strings

    International Nuclear Information System (INIS)

    Popov, A.D.

    1991-01-01

    We introduce hyperbolic strings as closed bosonic strings with the target space R d-1,1 xT q+1,1 which has an additional time-like dimension in the internal space. The Fock spaces of the q-parametric family of standard bosonic, fermionic and heterotic strings with the target spaces of dimension n≤d+q are shown to be embedded into the Fock space of hyperbolic strings. The condition of the absence of anomaly fixes d and q for all three types of strings written in a bosonized form. (orig.)

  16. Chains of N=2, D=4 heterotic type II duals

    CERN Document Server

    Aldazabal, G; Font, A; Quevedo, Fernando

    1996-01-01

    We report on a search for N=2 heterotic strings that are dual candidates of type II compactifications on Calabi-Yau threefolds described as K3 fibrations. We find many new heterotic duals by using standard orbifold techniques. The associated type II compactifications fall into chains in which the proposed duals are heterotic compactifications related one another by a sequential Higgs mechanism. This breaking in the heterotic side typically involves the sequence SU(4)\\rightarrow SU(3)\\rightarrow SU(2)\\rightarrow 0, while in the type II side the weights of the complex hypersurfaces and the structure of the K3 quotient singularities also follow specific patterns.

  17. Topological amplitudes in heterotic superstring theory

    International Nuclear Information System (INIS)

    Antoniadis, I.; Taylor, T.R.

    1996-06-01

    We show that certain heterotic string amplitudes are given in terms of correlators of the twisted topological (2,0) SCFT, corresponding to the internal sector of the N = 1 spacetime supersymmetric background. The genus g topological partition function F g corresponds to a term in the effective action of the form W 2g , where W is the gauge or gravitational superfield. We study also recursion relations related to holomorphic anomalies, showing that, contrary to the type II case, they involve correlators of anti-chiral superfields. The corresponding terms in the effective action are of the form W 2g II n , where II is a chiral superfield obtained by chiral projection of a general superfield. We observe that the structure of the recursion relations is that of N = 1 spacetime supersymmetry Ward identity. We give also a solution of the tree level recursion relations and discuss orbifold examples. (author). 23 refs, 2 figs

  18. Fermionization of strings, and their conformal invariant solutions

    International Nuclear Information System (INIS)

    Abdalla, E.; Abdalla, M.C.B.

    1987-01-01

    The fermionic description of bosonic string theory, which turns out to be a Thirring model, is given. The relation of continuous spin to compactification is discussed, and regular solutions with finitely many fields can be found if the spin is a rational number. The relation between W.Z.W. theory and SU (n) Thirring model is also treated. (Author) [pt

  19. String Theory and M-Theory

    Science.gov (United States)

    Becker, Katrin; Becker, Melanie; Schwarz, John H.

    String theory is one of the most exciting and challenging areas of modern theoretical physics. This book guides the reader from the basics of string theory to recent developments. It introduces the basics of perturbative string theory, world-sheet supersymmetry, space-time supersymmetry, conformal field theory and the heterotic string, before describing modern developments, including D-branes, string dualities and M-theory. It then covers string geometry and flux compactifications, applications to cosmology and particle physics, black holes in string theory and M-theory, and the microscopic origin of black-hole entropy. It concludes with Matrix theory, the AdS/CFT duality and its generalizations. This book is ideal for graduate students and researchers in modern string theory, and will make an excellent textbook for a one-year course on string theory. It contains over 120 exercises with solutions, and over 200 homework problems with solutions available on a password protected website for lecturers at www.cambridge.org/9780521860697. Comprehensive coverage of topics from basics of string theory to recent developments Ideal textbook for a one-year course in string theory Includes over 100 exercises with solutions Contains over 200 homework problems with solutions available to lecturers on-line

  20. Exact solutions in string-motivated scalar-field cosmology

    International Nuclear Information System (INIS)

    Oezer, M.; Taha, M.O.

    1992-01-01

    Two exact cosmological solutions to a scalar-field potential motivated by six-dimensional (6D) Einstein-Maxwell theory are given. The resulting pure scalar-field cosmology is free of singularity and causality problems but conserves entropy. These solutions are then extended into exact cosmological solutions for a decaying scalar field with an approximate two-loop 4D string potential. The resulting cosmology is, for both solutions, free of cosmological problems and close to the standard cosmology of the radiation era

  1. A one-loop test of string duality

    International Nuclear Information System (INIS)

    Vafa, C.

    1995-01-01

    We test Type IIA-heterotic string duality in six dimensions by showing that the sigma model anomaly of the heterotic string is generated by a combination of a tree level and a string one-loop correction on the Type IIA side. (orig.)

  2. A Metric for Heterotic Moduli

    Science.gov (United States)

    Candelas, Philip; de la Ossa, Xenia; McOrist, Jock

    2017-12-01

    Heterotic vacua of string theory are realised, at large radius, by a compact threefold with vanishing first Chern class together with a choice of stable holomorphic vector bundle. These form a wide class of potentially realistic four-dimensional vacua of string theory. Despite all their phenomenological promise, there is little understanding of the metric on the moduli space of these. What is sought is the analogue of special geometry for these vacua. The metric on the moduli space is important in phenomenology as it normalises D-terms and Yukawa couplings. It is also of interest in mathematics, since it generalises the metric, first found by Kobayashi, on the space of gauge field connections, to a more general context. Here we construct this metric, correct to first order in {α^{\\backprime}}, in two ways: first by postulating a metric that is invariant under background gauge transformations of the gauge field, and also by dimensionally reducing heterotic supergravity. These methods agree and the resulting metric is Kähler, as is required by supersymmetry. Checking the metric is Kähler is intricate and the anomaly cancellation equation for the H field plays an essential role. The Kähler potential nevertheless takes a remarkably simple form: it is the Kähler potential of special geometry with the Kähler form replaced by the {α^{\\backprime}}-corrected hermitian form.

  3. Unification of string dualities

    International Nuclear Information System (INIS)

    Sen, A.

    1997-01-01

    We argue that all conjectured dualities involving various string, M- and F-theory compactifications can be 'derived' from the conjectured duality between type I and SO(32) heterotic string theory, T-dualities and the definition of M-and F-theories. (orig.)

  4. Heterotic weight lifting

    Energy Technology Data Exchange (ETDEWEB)

    Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)

    2010-03-21

    We describe a method for constructing genuinely asymmetric (2,0) heterotic strings out of N=2 minimal models in the fermionic sector, whereas the bosonic sector is only partly build out of N=2 minimal models. This is achieved by replacing one minimal model plus the superfluous E{sub 8} factor by a non-supersymmetric CFT with identical modular properties. This CFT generically lifts the weights in the bosonic sector, giving rise to a spectrum with fewer massless states. We identify more than 30 such lifts, and we expect many more to exist. This yields more than 450 different combinations. Remarkably, despite the lifting of all Ramond states, it is still possible to get chiral spectra. Even more surprisingly, these chiral spectra include examples with a certain number of chiral families of SO(10), SU(5) or other subgroups, including just SU(3)xSU(2)xU(1). The number of families and mirror families is typically smaller than in standard Gepner models. Furthermore, in a large number of different cases, spectra with three chiral families can be obtained. Based on a first scan of about 10% of the lifted Gepner models we can construct, we have collected more than 10,000 distinct spectra with three families, including examples without mirror fermions. We present an example where the GUT group is completely broken to the standard model, but the resulting and inevitable fractionally charged particles are confined by an additional gauge group factor.

  5. Heterotic weight lifting

    International Nuclear Information System (INIS)

    Gato-Rivera, B.; Schellekens, A.N.

    2010-01-01

    We describe a method for constructing genuinely asymmetric (2,0) heterotic strings out of N=2 minimal models in the fermionic sector, whereas the bosonic sector is only partly build out of N=2 minimal models. This is achieved by replacing one minimal model plus the superfluous E 8 factor by a non-supersymmetric CFT with identical modular properties. This CFT generically lifts the weights in the bosonic sector, giving rise to a spectrum with fewer massless states. We identify more than 30 such lifts, and we expect many more to exist. This yields more than 450 different combinations. Remarkably, despite the lifting of all Ramond states, it is still possible to get chiral spectra. Even more surprisingly, these chiral spectra include examples with a certain number of chiral families of SO(10), SU(5) or other subgroups, including just SU(3)xSU(2)xU(1). The number of families and mirror families is typically smaller than in standard Gepner models. Furthermore, in a large number of different cases, spectra with three chiral families can be obtained. Based on a first scan of about 10% of the lifted Gepner models we can construct, we have collected more than 10,000 distinct spectra with three families, including examples without mirror fermions. We present an example where the GUT group is completely broken to the standard model, but the resulting and inevitable fractionally charged particles are confined by an additional gauge group factor.

  6. Solution of the dilaton problem in open bosonic string theories

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Z. (Los Alamos National Lab., NM (United States)); Dunbar, D.C. (Liverpool Univ. (United Kingdom))

    1991-01-01

    One of the most remarkable features of string theories is that they seem to provide a framework for a consistent theory of quantum gravity which is unified with all other forces. String theories fall into the two basic, a priori equally interesting, categories of open and closed string theories. For the past five years virtually all attention has been focused on purely closed string theories even though the reincarnation of string theory began with the discovery of anomaly cancellation and finiteness in the Green-Schwarz open superstring. It is the authors' purpose in this essay to rekindle interest in open string theories as potential theories of nature, including gravity. All string theories naively contain a massless dilaton which couples with the strength of gravity in direct violation of experiment. They present a simple mechanism for giving the dilaton a mass in unoriented open bosonic string theories.

  7. Solution of the dilaton problem in open bosonic string theories

    International Nuclear Information System (INIS)

    Bern, Z.; Dunbar, D.C.

    1991-01-01

    One of the most remarkable features of string theories is that they seem to provide a framework for a consistent theory of quantum gravity which is unified with all other forces. String theories fall into the two basic, a priori equally interesting, categories of open and closed string theories. For the past five years virtually all attention has been focused on purely closed string theories even though the reincarnation of string theory began with the discovery of anomaly cancellation and finiteness in the Green-Schwarz open superstring. It is the authors' purpose in this essay to rekindle interest in open string theories as potential theories of nature, including gravity. All string theories naively contain a massless dilaton which couples with the strength of gravity in direct violation of experiment. They present a simple mechanism for giving the dilaton a mass in unoriented open bosonic string theories

  8. Open strings in the SL(2, R) WZWN model with solution for a rigidly rotating string

    DEFF Research Database (Denmark)

    Lomholt, Michael Andersen; Larsen, A.L.

    2003-01-01

    Boundary conditions and gluing conditions for open strings and D-branes in the SL(2, R) WZWN model, corresponding to AdS , are discussed. Some boundary conditions and gluing conditions previously considered in the literature are shown to be incompatible with the variation principle. We then consi......Boundary conditions and gluing conditions for open strings and D-branes in the SL(2, R) WZWN model, corresponding to AdS , are discussed. Some boundary conditions and gluing conditions previously considered in the literature are shown to be incompatible with the variation principle. We...... then consider open string boundary conditions corresponding to a certain field-dependent gluing condition. This allows us to consider open strings with constant energy and angular momentum. Classically, these open strings naturally generalize the open strings in flat Minkowski space. For rigidly rotating open...

  9. BPS string solutions in non-Abelian Yang-Mills theories

    Energy Technology Data Exchange (ETDEWEB)

    Kneipp, Marco A.C.; Brockill, Patrick [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]. E-mail: kneipp@cbpf.br; brockill@cbpf.br

    2001-04-01

    Starting from the bosonic part of N=2 Super QCD with a 'Seiberg-Witten' N = 2 breaking mass term, we obtain string BPS conditions for arbitrary semi-simple gauge groups. We show that the vacuum structure is compatible with a symmetry breaking scheme which allows the existence of Z{sub k}-strings and which has Spin (10) {yields} SU(5) x Z{sub 2} as a particular case. We obtain BPS Z{sub k}-string solutions and show that they satisfy the same first order differential equations and string tension as the BPS string for the U(1) case. (author)

  10. Some solutions of the equations of motion of the relativistic string with massive ends

    International Nuclear Information System (INIS)

    Barbashov, B.M.

    1977-01-01

    The classical theory is discussed for the relativistic string with point masses at its ends. The dynamical equations are solved for the class of motions of this system when the time evolution parameter tau is the proper time of both massive string ends. In this case the solution of the boundary equations is given by the almost periodic functions. Constraints on the normal modes resulting from the orthonormal gauge conditions differ essentially from the Virasoro ones. Incidentally one obtains an exact solution for the half-infinite string with mass at one end. It is also proved that the exact solution for the string with massive ends cannot be a periodic function. (Auth.)

  11. Heterotic/type I duality and D-brane instantons

    Science.gov (United States)

    Bachas, C.; Fabre, C.; Kiritsis, E.; Obers, N. A.; Vanhove, P.

    1998-01-01

    We study heterotic/type I duality in d = 8, 9 uncompactified dimensions. We consider the special ("BPS-saturated") F4 and R4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side.

  12. Heterotic/type I duality and D-brane instantons

    International Nuclear Information System (INIS)

    Bachas, C.; Fabre, C.; Vanhove, P.

    1998-01-01

    We study heterotic/type I duality in d=8,9 uncompactified dimensions. We consider the special (''BPS-saturated'') F 4 and R 4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be motivated as arising from a D-brane instanton calculation on the type I side. (orig.)

  13. Heterotic / type-I duality and D-brane instantons

    CERN Document Server

    Bachas, C P; Kiritsis, Elias B; Obers, N A; Vanhove, P

    1998-01-01

    We study heterotic/type-I duality in d=8,9 uncompactified dimensions. We consider the special (``BPS saturated'') F^4 and R^4 terms in the effective one-loop heterotic action, which are expected to be non-perturbatively exact. Under the standard duality map these translate to tree-level, perturbative and non-perturbative contributions on the type I side. We check agreement with the one-loop open string calculation, and discuss the higher-order perturbative contributions, which arise because of the mild non-holomorphicities of the heterotic elliptic genus. We put the heterotic world-sheet instanton corrections in a form that can be recognized easily as arising from a D-brane instanton calculation on the type-I side.

  14. Heterotic non-Abelian orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Maximilian [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Ramos-Sanchez, Saul [UNAM, Mexico (Mexico). Dept. of Theoretical Physics; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-04-15

    We perform the first systematic analysis of particle spectra obtained from heterotic string compactifications on non-Abelian toroidal orbifolds. After developing a new technique to compute the particle spectrum in the case of standard embedding based on higher dimensional supersymmetry, we compute the Hodge numbers for all recently classified 331 non-Abelian orbifold geometries which yield N=1 supersymmetry for heterotic compactifications. Surprisingly, most Hodge numbers follow the empiric pattern h{sup (1,1)}-h{sup (2,1)}=0 mod 6, which might be related to the number of three standard model generations. Furthermore, we study the fundamental groups in order to identify the possibilities for non-local gauge symmetry breaking. Three examples are discussed in detail: the simplest non-Abelian orbifold S{sub 3} and two more elaborated examples, T{sub 7} and {Delta}(27), which have only one untwisted Kaehler and no untwisted complex structure modulus. Such models might be especially interesting in the context of no-scale supergravity. Finally, we briefly discuss the case of orbifolds with vanishing Euler numbers in the context of enhanced (spontaneously broken) supersymmetry.

  15. Spin(7) compactifications and 1/4-BPS vacua in heterotic supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Angus, Stephen [Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS),Daejeon, 34051 Republic of (Korea, Republic of); Matti, Cyril [Department of Mathematics, City University, Northampton Square, London, EC1V 0HB (United Kingdom); Mandelstam Institute for Theoretical Physics, NITheP, andSchool of Physics, University of the Witwatersrand,Johannesburg, WITS 2050 South Africa (South Africa); Svanes, Eirik E. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7589, LPTHE,Paris, F-75005 (France); CNRS, UMR 7589, LPTHE,Paris, F-75005 (France); Sorbonne Universités, Institut Lagrange de Paris,98 bis Bd Arago, Paris, 75014 (France)

    2016-03-25

    We continue the investigation into non-maximally symmetric compactifications of the heterotic string. In particular, we consider compactifications where the internal space is allowed to depend on two or more external directions. For preservation of supersymmetry, this implies that the internal space must in general be that of a Spin(7) manifold, which leads to a 1/4-BPS four-dimensional supersymmetric perturbative vacuum breaking all but one supercharge. We find that these solutions allow for internal geometries previously excluded by the domain-wall-type solutions, and hence the resulting four-dimensional superpotential is more generic. In particular, we find an interesting resemblance to the superpotentials that appear in non-geometric flux compactifications of type II string theory. If the vacua are to be used for phenomenological applications, they must be lifted to maximal symmetry by some non-perturbative or higher-order effect.

  16. On multibrane solutions in open string field theory

    Czech Academy of Sciences Publication Activity Database

    Murata, Masaki; Schnabl, Martin

    2011-01-01

    Roč. 2011, č. 188 (2011), s. 50-55 ISSN 0375-9687. [International Conference on String Field Theory and Related Aspects (SFT2010). Kyoto, 18.10.2010-22.10.2010] Grant - others:EUROHORC and ESF(XE) EYI/07/E010 Institutional research plan: CEZ:AV0Z10100502 Keywords : string field theory * D-branes * open strings Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.063, year: 2011 http://ptp.ipap.jp/link?PTPS/188/50/

  17. Heterotic model building: 16 special manifolds

    International Nuclear Information System (INIS)

    He, Yang-Hui; Lee, Seung-Joo; Lukas, Andre; Sun, Chuang

    2014-01-01

    We study heterotic model building on 16 specific Calabi-Yau manifolds constructed as hypersurfaces in toric four-folds. These 16 manifolds are the only ones among the more than half a billion manifolds in the Kreuzer-Skarke list with a non-trivial first fundamental group. We classify the line bundle models on these manifolds, both for SU(5) and SO(10) GUTs, which lead to consistent supersymmetric string vacua and have three chiral families. A total of about 29000 models is found, most of them corresponding to SO(10) GUTs. These models constitute a starting point for detailed heterotic model building on Calabi-Yau manifolds in the Kreuzer-Skarke list. The data for these models can be downloaded http://www-thphys.physics.ox.ac.uk/projects/CalabiYau/toricdata/index.html.

  18. Universality in radiative corrections for non-supersymmetric heterotic vacua

    CERN Document Server

    Angelantonj, C; Tsulaia, Mirian

    2016-01-01

    Properties of moduli-dependent gauge threshold corrections in non-supersymmetric heterotic vacua are reviewed. In the absence of space-time supersymmetry these amplitudes are no longer protected and receive contributions from the whole tower of string states, BPS and not. Never-theless, the difference of gauge thresholds for non-Abelian gauge groups displays a remarkable universality property, even when supersymmetry is absent. We present a simple heterotic construction that shares this universal behaviour and expose the necessary conditions on the super-symmetry breaking mechanism for universality to occur.

  19. The solution space of the unitary matrix model string equation and the Sato Grassmannian

    International Nuclear Information System (INIS)

    Anagnostopoulos, K.N.; Bowick, M.J.; Schwarz, A.

    1992-01-01

    The space of all solutions to the string equation of the symmetric unitary one-matrix model is determined. It is shown that the string equations is equivalent to simple conditions on points V 1 and V 2 in the big cell Gr (0) of the Sato Grassmannian Gr. This is a consequence of a well-defined continuum limit in which the string equation has the simple form [P, 2 - ]=1, with P and 2 - 2x2 matrices of differential operators. These conditions on V 1 and V 2 yield a simple system of first order differential equations whose analysis determines the space of all solutions to the string equation. This geometric formulation leads directly to the Virasoro constraints L n (n≥0), where L n annihilate the two modified-KdV τ-functions whose product gives the partition function of the Unitary Matrix Model. (orig.)

  20. Sectors of solutions and minimal energies in classical Liouville theories for strings

    International Nuclear Information System (INIS)

    Johansson, L.; Kihlberg, A.; Marnelius, R.

    1984-01-01

    All classical solutions of the Liouville theory for strings having finite stable minimum energies are calculated explicitly together with their minimal energies. Our treatment automatically includes the set of natural solitonlike singularities described by Jorjadze, Pogrebkov, and Polivanov. Since the number of such singularities is preserved in time, a sector of solutions is not only characterized by its boundary conditions but also by its number of singularities. Thus, e.g., the Liouville theory with periodic boundary conditions has three different sectors of solutions with stable minimal energies containing zero, one, and two singularities. (Solutions with more singularities have no stable minimum energy.) It is argued that singular solutions do not make the string singular and therefore may be included in the string quantization

  1. Asymmetric Gepner models II. Heterotic weight lifting

    Energy Technology Data Exchange (ETDEWEB)

    Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)

    2011-05-21

    A systematic study of 'lifted' Gepner models is presented. Lifted Gepner models are obtained from standard Gepner models by replacing one of the N=2 building blocks and the E{sub 8} factor by a modular isomorphic N=0 model on the bosonic side of the heterotic string. The main result is that after this change three family models occur abundantly, in sharp contrast to ordinary Gepner models. In particular, more than 250 new and unrelated moduli spaces of three family models are identified. We discuss the occurrence of fractionally charged particles in these spectra.

  2. Asymmetric Gepner models II. Heterotic weight lifting

    International Nuclear Information System (INIS)

    Gato-Rivera, B.; Schellekens, A.N.

    2011-01-01

    A systematic study of 'lifted' Gepner models is presented. Lifted Gepner models are obtained from standard Gepner models by replacing one of the N=2 building blocks and the E 8 factor by a modular isomorphic N=0 model on the bosonic side of the heterotic string. The main result is that after this change three family models occur abundantly, in sharp contrast to ordinary Gepner models. In particular, more than 250 new and unrelated moduli spaces of three family models are identified. We discuss the occurrence of fractionally charged particles in these spectra.

  3. Non-linear σ-models and string theories

    International Nuclear Information System (INIS)

    Sen, A.

    1986-10-01

    The connection between σ-models and string theories is discussed, as well as how the σ-models can be used as tools to prove various results in string theories. Closed bosonic string theory in the light cone gauge is very briefly introduced. Then, closed bosonic string theory in the presence of massless background fields is discussed. The light cone gauge is used, and it is shown that in order to obtain a Lorentz invariant theory, the string theory in the presence of background fields must be described by a two-dimensional conformally invariant theory. The resulting constraints on the background fields are found to be the equations of motion of the string theory. The analysis is extended to the case of the heterotic string theory and the superstring theory in the presence of the massless background fields. It is then shown how to use these results to obtain nontrivial solutions to the string field equations. Another application of these results is shown, namely to prove that the effective cosmological constant after compactification vanishes as a consequence of the classical equations of motion of the string theory. 34 refs

  4. Introduction to strings and superstrings

    International Nuclear Information System (INIS)

    Traubenberg, M.R. de.

    1988-01-01

    We discuss the main features on the formulation of string theory that, in a primitive level, describe the hadronic phenomenon of duality. We also study an extension of the models of closed and strings with spin. Then, by using supersymmetry, it is formulated the theory of superstrings and heterotic strings with the aim of unify the fundamental interactions and matter. (M.W.O.) [pt

  5. On string solutions of Bethe equations in N=4 supersymmetric Yang-Mills theory

    International Nuclear Information System (INIS)

    Bytsko, A.G.; Shenderovich, I.E.

    2007-12-01

    The Bethe equations, arising in description of the spectrum of the dilatation operator for the su(2) sector of the N=4 supersymmetric Yang-Mills theory, are considered in the anti-ferromagnetic regime. These equations are deformation of those for the Heisenberg XXX magnet. It is proven that in the thermodynamic limit roots of the deformed equations group into strings. It is proven that the corresponding Yang's action is convex, which implies uniqueness of solution for centers of the strings. The state formed of strings of length (2n+1) is considered and the density of their distribution is found. It is shown that the energy of such a state decreases as n grows. It is observed that non-analyticity of the left hand side of the Bethe equations leads to an additional contribution to the density and energy of strings of even length. Whence it is concluded that the structure of the anti-ferromagnetic vacuum is determined by the behaviour of exponential corrections to string solutions in the thermodynamic limit and possibly involves strings of length 2. (orig.)

  6. On string solutions of Bethe equations in N=4 supersymmetric Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Bytsko, A.G. [Rossijskaya Akademiya Nauk, St. Petersburg (Russian Federation). Inst. Matematiki]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Shenderovich, I.E. [St. Petersburg State Univ. (Russian Federation). Physics Dept.

    2007-12-15

    The Bethe equations, arising in description of the spectrum of the dilatation operator for the su(2) sector of the N=4 supersymmetric Yang-Mills theory, are considered in the anti-ferromagnetic regime. These equations are deformation of those for the Heisenberg XXX magnet. It is proven that in the thermodynamic limit roots of the deformed equations group into strings. It is proven that the corresponding Yang's action is convex, which implies uniqueness of solution for centers of the strings. The state formed of strings of length (2n+1) is considered and the density of their distribution is found. It is shown that the energy of such a state decreases as n grows. It is observed that non-analyticity of the left hand side of the Bethe equations leads to an additional contribution to the density and energy of strings of even length. Whence it is concluded that the structure of the anti-ferromagnetic vacuum is determined by the behaviour of exponential corrections to string solutions in the thermodynamic limit and possibly involves strings of length 2. (orig.)

  7. Electric magnetic duality in string theory

    International Nuclear Information System (INIS)

    Sen, A.

    1992-07-01

    The electric-magnetic duality transformation in four dimensional heterotic string theory discussed by Shapere, Trivedi and Wilczek is shown to be an exact symmetry of the equations of motion of low energy effective field theory even after including the scalar and the vector fields, arising due to compactification, in the effective field theory. Using this duality transformation we construct rotating black hole solutions in the effective field theory carrying both electric and magnetic charges. The spectrum of extremal magnetically charged black holes turn out to be similar to that of electrically charged elementary string excitations lying on the leading Regge trajectory. We also discuss the possibility that the duality symmetry is an exact symmetry of the full string theory under which electrically charged elementary string excitations get exchanged with magnetically charged soliton like solutions. This proposal might be made concrete following the suggestion of Dabholkar et. al. that fundamental strings may be regarded as soliton like classical solutions in the effective field theory. (author). 20 refs

  8. Heterotic particle models from various perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Blaszczyk, Michael I.

    2012-10-15

    We consider the compactification of heterotic string theory on toroidal orbifolds and their resolutions. In the framework of gauged linear sigma models we develop realizations of such spaces, allowing to continously vary the moduli and thus smoothly interpolate between different corners of the theory. This way all factorizable orbifold resolutions as well as some non-factorizable ones can be obtained. We find that for a given geometry there are many model which realize it as a target space, differing in their complexity. We explore regions of moduli space which otherwise would not be accessible. In particular we are interested in the orbifold regime, where exact string calculations are possible, and the large volume regime, where techniques of supergravity compactification can be applied. By comparing these two theories and matching the spectra we find evidence for non-perturbative effects which interpolate between these regimes.

  9. Large-N behaviour of string solutions in the Heisenberg model

    CERN Document Server

    Fujita, T; Takahashi, H

    2003-01-01

    We investigate the large-N behaviour of the complex solutions for the two-magnon system in the S = 1/2 Heisenberg XXZ model. The Bethe ansatz equations are numerically solved for the string solutions with a new iteration method. Clear evidence of the violation of the string configurations is found at N = 22, 62, 121, 200, 299, 417, but the broken states are still Bethe states. The number of Bethe states is consistent with the exact diagonalization, except for one singular state.

  10. R-parity from the heterotic string

    International Nuclear Information System (INIS)

    Gaillard, Mary K.

    2004-01-01

    In T-duality invariant effective supergravity with gaugino condensation as the mechanism for supersymmetry breaking, there is a residual discrete symmetry that could play the role of R-parity in supersymmetric extensions of the Standard Model

  11. Grand unification in the heterotic brane world

    International Nuclear Information System (INIS)

    Vaudrevange, Patrick Karl Simon

    2008-08-01

    String theory is known to be one of the most promising candidates for a uni ed description of all elementary particles and their interactions. Starting from the ten-dimensional heterotic string, we study its compactification on six-dimensional orbifolds. We clarify some important technical aspects of their construction and introduce new parameters, called generalized discrete torsion. We identify intrinsic new relations between orbifolds with and without (generalized) discrete torsion. Furthermore, we perform a systematic search for MSSM-like models in the context of Z 6 -II orbifolds. Using local GUTs, which naturally appear in the heterotic brane world, we construct about 200 MSSM candidates. We find that intermediate SUSY breaking through hidden sector gaugino condensation is preferred in this set of models. A specific model, the so-called benchmark model, is analyzed in detail addressing questions like the identification of a supersymmetric vacuum with a naturally small μ-term and proton decay. Furthermore, as vevs of twisted fields correspond to a resolution of orbifold singularities, we analyze the resolution of Z 3 singularities in the local and in the compact case. Finally, we exemplify this procedure with the resolution of a Z 3 MSSM candidate. (orig.)

  12. Grand unification in the heterotic brane world

    Energy Technology Data Exchange (ETDEWEB)

    Vaudrevange, Patrick Karl Simon

    2008-08-15

    String theory is known to be one of the most promising candidates for a uni ed description of all elementary particles and their interactions. Starting from the ten-dimensional heterotic string, we study its compactification on six-dimensional orbifolds. We clarify some important technical aspects of their construction and introduce new parameters, called generalized discrete torsion. We identify intrinsic new relations between orbifolds with and without (generalized) discrete torsion. Furthermore, we perform a systematic search for MSSM-like models in the context of Z{sub 6}-II orbifolds. Using local GUTs, which naturally appear in the heterotic brane world, we construct about 200 MSSM candidates. We find that intermediate SUSY breaking through hidden sector gaugino condensation is preferred in this set of models. A specific model, the so-called benchmark model, is analyzed in detail addressing questions like the identification of a supersymmetric vacuum with a naturally small {mu}-term and proton decay. Furthermore, as vevs of twisted fields correspond to a resolution of orbifold singularities, we analyze the resolution of Z{sub 3} singularities in the local and in the compact case. Finally, we exemplify this procedure with the resolution of a Z{sub 3} MSSM candidate. (orig.)

  13. Introduction to string theory and string compactifications

    International Nuclear Information System (INIS)

    GarcIa-Compean, Hugo

    2005-01-01

    Basics of some topics on perturbative and non-perturbative string theory are reviewed. After a mathematical survey of the Standard Model of particle physics and GUTs, the bosonic string kinematics for the free case and with interaction is described. The effective action of the bosonic string and the spectrum is also discussed. T-duality in closed and open strings and the definition of D-brane are surveyed. Five perturbative superstring theories and their spectra is briefly outlined. Calabi-Yau three-fold compactifications of heterotic strings and their relation to some four-dimensional physics are given. Finally, non-perturbative issues like S-duality, M-theory and F-theory are also reviewed

  14. Folded three-spin string solutions in AdS5 x S5

    International Nuclear Information System (INIS)

    Ryang Shijong

    2004-01-01

    We construct a spinning closed string solution in AdS 5 x S 5 which is folded in the radial direction and has two equal spins in AdS 5 and a spin in S 5 . The energy expression of the three-spin solution specified by the folding and winding numbers for the small S 5 spin shows a logarithmic behavior and a one-third power behavior of the large total AdS 5 spin, in the long string and in the short string located near the boundary of AdS 5 respectively. It exhibits the non-regular expansion in the 't Hooft coupling constant, while it takes the regular one when the S 5 spin becomes large. (author)

  15. Topics in string theory

    International Nuclear Information System (INIS)

    Neveu, A.

    1986-01-01

    There exist several string models. In the first lecture, the simplest one, the open bosonic string, which turns out to live most naturally in 26 dimensions will be described in some detail. In the second lecture, the closed bosonic strings, and the open and closed 10-dimensional strings (superstrings) are reviewed. In the third lecture, various compactification schemes which have been proposed to deal with the extra space dimensions, from 4 to 10 or 26 are dealt with; in particular, the Frenkel-Kac construction which builds non-Abelian internal symmetry groups out of the compactified dimensions, and the resulting heterotic string are described. Finally, in the fourth lecture, the important problem of the second quantization of string theories, and of the underlying gauge invariance which is responsible for the possibility of dealing, in a consistent fashion, with interacting high-spin states without negative metric is addressed. 41 references, 8 figures

  16. Entropy of non-extreme rotating black holes in string theories

    International Nuclear Information System (INIS)

    Youm, D.

    1998-01-01

    We formulate the Rindler space description of rotating black holes in string theories. We argue that the comoving frame is the natural frame for studying the thermodynamics of rotating black holes and the statistical analysis of rotating black holes gets simplified in this frame. We also calculate statistical entropies of a general class of rotating black holes in heterotic strings on tori by applying the D-brane description and the correspondence principle. We find at least a qualitative agreement between the Bekenstein-Hawking entropies and the statistical entropies of these black hole solutions. (orig.)

  17. D-brane description of new open string solutions in AdS5

    International Nuclear Information System (INIS)

    Kluson, J.

    2008-01-01

    In this Letter we find D-brane descriptions of some of new open string solutions that were found in (0804.3438 [hep-th]). These D5-brane and D3-brane configurations give gravitational dual descriptions of Wilson loops in some particular representations

  18. Heterotic α ’-corrections in Double Field Theory

    OpenAIRE

    Bedoya, OscarInstituto de Astronomía y Física del Espacio (CONICET-UBA), Ciudad Universitaria, Buenos Aires, Argentina; Marqués, Diego(Instituto de Astronomía y Física del Espacio (CONICET-UBA), Ciudad Universitaria, Buenos Aires, Argentina); Núñez, Carmen(Instituto de Astronomía y Física del Espacio (CONICET-UBA), Ciudad Universitaria, Buenos Aires, Argentina)

    2014-01-01

    We extend the generalized flux formulation of Double Field Theory to include all the first order bosonic contributions to the α′ expansion of the heterotic string low energy effective theory. The generalized tangent space and duality group are enhanced by α′ corrections, and the gauge symmetries are generated by the usual (gauged) generalized Lie derivative in the extended space. The generalized frame receives derivative corrections through the spin connection with torsion, which is incorpora...

  19. Generalized string theory mapping relations between gravity and gauge theory

    International Nuclear Information System (INIS)

    Bjerrum-Bohr, N.E.J.

    2003-01-01

    A previous study of the Kawai, Lewellen and Tye (KLT) relations between gravity and gauge theories, imposed by the relationship of closed and open strings, are here extended in the light of general relativity and Yang-Mills theory as effective field theories. We discuss the possibility of generalizing the traditional KLT mapping in this effective setting. A generalized mapping between the effective Lagrangians of gravity and Yang-Mills theory is presented, and the corresponding operator relations between gauge and gravity theories at the tree level are further explored. From this generalized mapping remarkable diagrammatic relations are found, linking diagrams in gravity and Yang-Mills theory, as well as diagrams in pure effective Yang-Mills theory. Also the possibility of a gravitational coupling to an antisymmetric field in the gravity scattering amplitude is considered, and shown to allow for mixed open-closed string solutions, i.e., closed heterotic strings

  20. A new exact solution to the classical equations of motion of the relativistic string with massive ends

    International Nuclear Information System (INIS)

    Barbashov, B.M.; Chervyakov, A.M.

    1991-01-01

    The classical histories of the relativistic string with massive ends in space-time are examined in terms of geometric invariants of both the string world surface and world lines of the point masses at the string ends. In this formulation the string variables are completely defined by means of the constant curvatures and torsions of the endpoint trajectories which are subjected to a system of differential equations with a delayed arguments that incorporates retardation effects of the interaction of two point masses through the string. The well-known example of the rotating straight-line string with massive ends corresponds to a particular solution of this system for the constant torsions. A new exact solution for the periodic torsions of the world trajectories of the massive string ends is found. In this case the string coordinates are represented in terms of normal elliptic integrals and describe a more intricate motion including its transverse vibrations than rotation of a stretched string in a given plane. 17 refs

  1. On moduli stabilisation and de Sitter vacua in MSSM heterotic orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Parameswaran, Susha L. [Uppsala Univ. (Sweden). Dept. of Physics and Astronomy; Ramos-Sanchez, Saul [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zavala, Ivonne [Bonn Univ. (Germany). Bethe Center for Theoretical Physics and Physikalisches Inst.

    2010-09-15

    We study the problem of moduli stabilisation in explicit heterotic orbifold compactifications, whose spectra contain the MSSM plus some vector-like exotics that can be decoupled. Considering all the bulk moduli, we obtain the 4D low energy effective action for the compactification, which has contributions from various, computable, perturbative and non-perturbative effects. Hidden sector gaugino condensation and string worldsheet instantons result in a combination of racetrack, KKLT and cusp-form contributions to the superpotential, which lift all the bulk moduli directions. We point out the properties observed in our concrete models, which tend to be missed when only ''generic'' features of a model are assumed. We search for interesting vacua and find several de Sitter solutions, but so far, they all turn out to be unstable. (orig.)

  2. Functional integral approach to string theories

    International Nuclear Information System (INIS)

    Sakita, B.

    1987-01-01

    Fermionic string theory can be made supersymmetric: the superstring. It contains among others mass zero gauge fields of spin 1 and 2. The recent revival of interests in string field theories is due to the recognition of the compactified superstring theory as a viable theory of grandunification of all interactions, especially after Green and Schwarz's discovery of the gauge and gravitational anomaly cancellation in 0(32) superstring theory. New developments include string phenomenology, general discussions of compactification, new models, especially the heterotic string. These are either applications or extensions of string field theories. Although these are very exciting developments, the author limits his attention to the basics of the bosonic string theory

  3. Superstrings fermionic solutions

    International Nuclear Information System (INIS)

    Rausch de Traubenberg, M.

    1990-06-01

    The solutions proposed by the superstring theory are classified and compared. In order to obtain some of the equivalences, the demonstration is based on the coincidence of the excitation spectrum and the quantum numbers from different states. The fermionic representation of the heterotical strings is discussed. The conformal invariance and the supersymmetric results extended to two dimensions are investigated. Concerning the fermionic strings, the formalism and a phenomenological solution involving three families of quarks, chiral leptons and leptons from the E 6 gauge group are presented. The equivalence between real and complex fermions is discussed. The similarity between some of the solutions of the Wess-Zumino-Witten model and the orbifolds is considered. The formal calculation program developed for reproducing the theory's low energy spectra, in the fermionic string formalism is given [fr

  4. Inverse Scattering Method and Soliton Solution Family for String Effective Action

    International Nuclear Information System (INIS)

    Ya-Jun, Gao

    2009-01-01

    A modified Hauser–Ernst-type linear system is established and used to develop an inverse scattering method for solving the motion equations of the string effective action describing the coupled gravity, dilaton and Kalb–Ramond fields. The reduction procedures in this inverse scattering method are found to be fairly simple, which makes the proposed inverse scattering method applied fine and effective. As an application, a concrete family of soliton solutions for the considered theory is obtained

  5. Higgs versus matter in the heterotic landscape

    International Nuclear Information System (INIS)

    Buchmueller, W.; Schmidt, J.

    2009-01-01

    In supersymmetric extensions of the standard model there is no basic difference between Higgs and matter fields, which leads to the well-known problem of potentially large baryon and lepton number violating interactions. Although these unwanted couplings can be forbidden by continuous or discrete global symmetries, a theoretical guiding principle for their choice is missing. We examine this problem for a class of vacua of the heterotic string compactified on an orbifold. As expected, in general there is no difference between Higgs and matter. However, certain vacua happen to possess unbroken matter parity and discrete R-symmetries which single out Higgs fields in the low energy effective field theory. We present a method how to identify maximal vacua in which the perturbative contribution to the μ-term and the expectation value of the superpotential vanish. Two vacua are studied in detail, one with two pairs of Higgs doublets and one with partial gauge-Higgs unification

  6. N = 1 dual string pairs and their modular superpotentials

    International Nuclear Information System (INIS)

    Luest, D.

    1998-01-01

    We review the duality between heterotic and F-theory string vacua with N=1 space-time supersymmetry in eight, six and four dimensions. In particular, we discuss two chains of four-dimensional F-theory/heterotic dual string pairs, where F-theory is compactified on certain elliptic Calabi-Yau fourfolds, and the dual heterotic vacua are given by compactifications on elliptic Calabi-Yau threefolds plus the specification of the E 8 x E 8 gauge bundles. We show that the massless spectra of the dual pairs agree by using, for one chain of models, an index formula to count the heterotic bundle moduli and determine the dual F-theory spectra from the Hodge numbers of the fourfolds and of the type IIB base spaces. Moreover as a further check, we demonstrate that for one particular heterotic/F-theory dual pair the N=1 superpotentials are the same. (orig.)

  7. Local grand unification in the heterotic landscape

    International Nuclear Information System (INIS)

    Schmidt, Jonas

    2009-06-01

    We consider the possibility that the unification of the electroweak interactions and the strong force arises from string theory, at energies significantly lower than the string scale. As a tool, an effective grand unified field theory in six dimensions is derived from an anisotropic orbifold compactification of the heterotic string. It is explicitly shown that all anomalies cancel in the model, though anomalous Abelian gauge symmetries are present locally at the boundary singularities. In the supersymmetric vacuum additional interactions arise from higher-dimensional operators. We develop methods that relate the couplings of the effective theory to the location of the vacuum, and find that unbroken discrete symmetries play an important role for the phenomenology of orbifold models. An efficient algorithm for the calculation of the superpotential to arbitrary order is developed, based on symmetry arguments. We furthermore present a correspondence between bulk fields of the orbifold model in six dimensions, and the moduli fields that arise from compactifying four internal dimensions on a manifold with non-trivial gauge background. (orig.)

  8. Local grand unification in the heterotic landscape

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Jonas

    2009-07-15

    We consider the possibility that the unification of the electroweak interactions and the strong force arises from string theory, at energies significantly lower than the string scale. As a tool, an effective grand unified field theory in six dimensions is derived from an anisotropic orbifold compactification of the heterotic string. It is explicitly shown that all anomalies cancel in the model, though anomalous Abelian gauge symmetries are present locally at the boundary singularities. In the supersymmetric vacuum additional interactions arise from higher-dimensional operators. We develop methods that relate the couplings of the effective theory to the location of the vacuum, and find that unbroken discrete symmetries play an important role for the phenomenology of orbifold models. An efficient algorithm for the calculation of the superpotential to arbitrary order is developed, based on symmetry arguments. We furthermore present a correspondence between bulk fields of the orbifold model in six dimensions, and the moduli fields that arise from compactifying four internal dimensions on a manifold with non-trivial gauge background. (orig.)

  9. Gravity from strings

    International Nuclear Information System (INIS)

    Deser, S.

    1987-01-01

    We obtain the Einstein action plus quadratic curvature corrections generated by closed bosonic, heterotic and supersymmetric strings by matching the four-graviton amplitude (to first order in the slope parameter and fourth power of momenta) with an effective local gravitational action. The resulting corrections are first shown to be of the Gauss-Bonnet form. It is then noted that, by the very nature of the slope expansion, the field-redefinition theorem applies. Consequently, only the curvature-squared term is determined, while squares of its contractions are explicitly seen not to contribute. This latter property has a generalization to all orders which implies that the effective gravitational action is unavoidably ghost-free. The properties of solutions to these corrected theories are then examined. First neglecting dilatons, we find the explicit 'Schwarzschild' metrics. Both asymptotically flat and de Sitter solutions are present. The latter are however shown to be unstable. The former have horizons and singularities which are respectively smaller and less violent than in Einstein gravity; the correct sign of the slope parameter also ensures absence of naked singularities. When dilatons are included, the cosmological vacua are gratifyingly excluded. (orig.)

  10. Local models of heterotic flux vacua: spacetime and worldsheet aspects

    International Nuclear Information System (INIS)

    Israel, D.; Carlevaro, L.

    2011-01-01

    We report on some recent progress in understanding heterotic flux compactifications, from a worldsheet perspective mainly. We consider local models consisting in torus fibration over warped Eguchi-Hanson space and non-Kaehler resolved conifold geometries. We analyze the supergravity solutions and define a double-scaling limit of the resolved singularities, defined such that the geometry is smooth and weakly coupled. We show that, remarkably, the heterotic solutions admit solvable worldsheet CFT descriptions in this limit. This allows in particular to understand the important role of worldsheet non-perturbative effects. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. The Infinitesimal Moduli Space of Heterotic G 2 Systems

    Science.gov (United States)

    de la Ossa, Xenia; Larfors, Magdalena; Svanes, Eirik E.

    2018-06-01

    Heterotic string compactifications on integrable G 2 structure manifolds Y with instanton bundles {(V,A), (TY,\\tilde{θ})} yield supersymmetric three-dimensional vacua that are of interest in physics. In this paper, we define a covariant exterior derivative D and show that it is equivalent to a heterotic G 2 system encoding the geometry of the heterotic string compactifications. This operator D acts on a bundle Q}=T^*Y \\oplus End(V) \\oplus End(TY)} and satisfies a nilpotency condition \\check{{D^2=0} , for an appropriate projection of D. Furthermore, we determine the infinitesimal moduli space of these systems and show that it corresponds to the finite-dimensional cohomology group H^1_{D}(Q). We comment on the similarities and differences of our result with Atiyah's well-known analysis of deformations of holomorphic vector bundles over complex manifolds. Our analysis leads to results that are of relevance to all orders in the {α'} expansion.

  12. On heterotic supermanifolds

    International Nuclear Information System (INIS)

    Randjbar-Daemi, S.; Salam, A.; Strathdee, J.

    1988-08-01

    The geometry of heterotic supermanifolds is discussed with particular reference to patching conditions and gauge fixing. Superfield formalism is used and the associated torsion constraints are solved explicitly in an arbitrary gauge, that is without imposing gauge conditions. Finite gauge transformations are constructed. The structure group associated with Wess-Zumino type gauges is obtained and is reduced by further refinements of the gauge conditions up to the stage at which the standard description of the super Riemann surface is recovered. It is shown that any invariant functional of the super 3-bein can depend only on a finite number of parameters, i.e. the moduli and super moduli. Chiral superfields and the structure of action functionals are discussed and, finally the integration measure in supermoduli space is derived by an application of the Faddeev-Popov prescription. (author). 15 refs

  13. Off-diagonal deformations of Kerr metrics and black ellipsoids in heterotic supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Vacaru, Sergiu I. [Quantum Gravity Research, Topanga, CA (United States); University ' ' Al. I. Cuza' ' , Project IDEI, Iasi (Romania); Irwin, Klee [Quantum Gravity Research, Topanga, CA (United States)

    2017-01-15

    Geometric methods for constructing exact solutions of equations of motion with first order α{sup '} corrections to the heterotic supergravity action implying a nontrivial Yang-Mills sector and six-dimensional, 6-d, almost-Kaehler internal spaces are studied. In 10-d spacetimes, general parametrizations for generic off-diagonal metrics, nonlinear and linear connections, and matter sources, when the equations of motion decouple in very general forms are considered. This allows us to construct a variety of exact solutions when the coefficients of fundamental geometric/physical objects depend on all higher-dimensional spacetime coordinates via corresponding classes of generating and integration functions, generalized effective sources and integration constants. Such generalized solutions are determined by generic off-diagonal metrics and nonlinear and/or linear connections; in particular, as configurations which are warped/compactified to lower dimensions and for Levi-Civita connections. The corresponding metrics can have (non-) Killing and/or Lie algebra symmetries and/or describe (1+2)-d and/or (1+3)-d domain wall configurations, with possible warping nearly almost-Kaehler manifolds, with gravitational and gauge instantons for nonlinear vacuum configurations and effective polarizations of cosmological and interaction constants encoding string gravity effects. A series of examples of exact solutions describing generic off-diagonal supergravity modifications to black hole/ellipsoid and solitonic configurations are provided and analyzed. We prove that it is possible to reproduce the Kerr and other type black solutions in general relativity (with certain types of string corrections) in the 4-d case and to generalize the solutions to non-vacuum configurations in (super-) gravity/string theories. (orig.)

  14. Off-diagonal deformations of Kerr metrics and black ellipsoids in heterotic supergravity

    International Nuclear Information System (INIS)

    Vacaru, Sergiu I.; Irwin, Klee

    2017-01-01

    Geometric methods for constructing exact solutions of equations of motion with first order α ' corrections to the heterotic supergravity action implying a nontrivial Yang-Mills sector and six-dimensional, 6-d, almost-Kaehler internal spaces are studied. In 10-d spacetimes, general parametrizations for generic off-diagonal metrics, nonlinear and linear connections, and matter sources, when the equations of motion decouple in very general forms are considered. This allows us to construct a variety of exact solutions when the coefficients of fundamental geometric/physical objects depend on all higher-dimensional spacetime coordinates via corresponding classes of generating and integration functions, generalized effective sources and integration constants. Such generalized solutions are determined by generic off-diagonal metrics and nonlinear and/or linear connections; in particular, as configurations which are warped/compactified to lower dimensions and for Levi-Civita connections. The corresponding metrics can have (non-) Killing and/or Lie algebra symmetries and/or describe (1+2)-d and/or (1+3)-d domain wall configurations, with possible warping nearly almost-Kaehler manifolds, with gravitational and gauge instantons for nonlinear vacuum configurations and effective polarizations of cosmological and interaction constants encoding string gravity effects. A series of examples of exact solutions describing generic off-diagonal supergravity modifications to black hole/ellipsoid and solitonic configurations are provided and analyzed. We prove that it is possible to reproduce the Kerr and other type black solutions in general relativity (with certain types of string corrections) in the 4-d case and to generalize the solutions to non-vacuum configurations in (super-) gravity/string theories. (orig.)

  15. Nonrelativistic closed string theory

    International Nuclear Information System (INIS)

    Gomis, Jaume; Ooguri, Hirosi

    2001-01-01

    We construct a Galilean invariant nongravitational closed string theory whose excitations satisfy a nonrelativistic dispersion relation. This theory can be obtained by taking a consistent low energy limit of any of the conventional string theories, including the heterotic string. We give a finite first order worldsheet Hamiltonian for this theory and show that this string theory has a sensible perturbative expansion, interesting high energy behavior of scattering amplitudes and a Hagedorn transition of the thermal ensemble. The strong coupling duals of the Galilean superstring theories are considered and are shown to be described by an eleven-dimensional Galilean invariant theory of light membrane fluctuations. A new class of Galilean invariant nongravitational theories of light-brane excitations are obtained. We exhibit dual formulations of the strong coupling limits of these Galilean invariant theories and show that they exhibit many of the conventional dualities of M theory in a nonrelativistic setting

  16. The NMSSM and string theory

    International Nuclear Information System (INIS)

    Lebedev, Oleg; Ramos-Sanchez, Saul

    2009-12-01

    We study the possibility of constructing the NMSSM from the heterotic string. String derived NMSSMs are much more rare than MSSMs due to the extra requirement that there exist a light singlet which couples to the Higgs pairs. They share the common feature that the singlet self-interactions are typically suppressed, leading to either the ''decoupling'' or to the Peccei-Quinn limit of the NMSSM. In the latter case, the spectrum contains a light pseudoscalar which may be relevant to the MSSM fine-tuning problem.We provide a Z 6 heterotic orbifold example of the NMSSM with approximate Peccei-Quinn symmetry, whose origin lies in the string selection rules combined with our choice of the vacuum configuration. (orig.)

  17. Strong/weak coupling duality relations for non-supersymmetric string theories

    International Nuclear Information System (INIS)

    Blum, J.D.; Dienes, K.R.

    1998-01-01

    Both the supersymmetric SO(32) and E 8 x E 8 heterotic strings in ten dimensions have known strong-coupling duals. However, it has not been known whether there also exist strong-coupling duals for the non-supersymmetric heterotic strings in ten dimensions. In this paper, we construct explicit open-string duals for the circle compactifications of several of these non-supersymmetric theories, among them the tachyon-free SO(16) x SO(16) string. Our method involves the construction of heterotic and open-string interpolating models that continuously connect non-supersymmetric strings to supersymmetric strings. We find that our non-supersymmetric dual theories have exactly the same massless spectra as their heterotic counterparts within a certain range of our interpolations. We also develop a novel method for analyzing the solitons of non-supersymmetric open-string theories, and find that the solitons of our dual theories also agree with their heterotic counterparts. These are therefore the first known examples of strong/weak coupling duality relations between non-supersymmetric, tachyon-free string theories. Finally, the existence of these strong-coupling duals allows us to examine the non-perturbative stability of these strings, and we propose a phase diagram for the behavior of these strings as a function of coupling and radius. (orig.)

  18. Heterotic Hyper-Kähler flux backgrounds

    Science.gov (United States)

    Halmagyi, Nick; Israël, Dan; Sarkis, Matthieu; Svanes, Eirik Eik

    2017-08-01

    We study Heterotic supergravity on Hyper-Kähler manifolds in the presence of non-trivial warping and three form flux with Abelian bundles in the large charge limit. We find exact, regular solutions for multi-centered Gibbons-Hawking spaces and Atiyah-Hitchin manifolds. In the case of Atiyah-Hitchin, regularity requires that the circle at infinity is of the same order as the instanton number, which is taken to be large. Alternatively there may be a non-trivial density of smeared five branes at the bolt.

  19. Quantum no-scale regimes in string theory

    Science.gov (United States)

    Coudarchet, Thibaut; Fleming, Claude; Partouche, Hervé

    2018-05-01

    We show that in generic no-scale models in string theory, the flat, expanding cosmological evolutions found at the quantum level can be attracted to a "quantum no-scale regime", where the no-scale structure is restored asymptotically. In this regime, the quantum effective potential is dominated by the classical kinetic energies of the no-scale modulus and dilaton. We find that this natural preservation of the classical no-scale structure at the quantum level occurs when the initial conditions of the evolutions sit in a subcritical region of their space. On the contrary, supercritical initial conditions yield solutions that have no analogue at the classical level. The associated intrinsically quantum universes are sentenced to collapse and their histories last finite cosmic times. Our analysis is done at 1-loop, in perturbative heterotic string compactified on tori, with spontaneous supersymmetry breaking implemented by a stringy version of the Scherk-Schwarz mechanism.

  20. The 10-D chiral null model and the relation to 4-D string solutions

    International Nuclear Information System (INIS)

    Behrndt, K.

    1994-12-01

    The chiral null model is a generalization of the fundamental string and gravitational wave background. It is an example of a conformally invariant model in all orders in α' and has unbroken supersymmetries. In a Kaluza-Klein approach we start in 10 dimensions and reduce the model down to 4 dimensions without making any restrictions. The 4-D field content is given by the metric, torsion, dilaton, a moduli field and 6 gauge fields. This model is self-dual and near the singularities asymptotically free. The relation to known IWP, Taub-NUT and rotating black hole solutions is discussed. (orig.)

  1. N =1 supergravitational heterotic galileons

    Science.gov (United States)

    Deen, Rehan; Ovrut, Burt

    2017-11-01

    Heterotic M -theory consists of a five-dimensional manifold of the form S 1 / Z 2 × M 4. It has been shown that one of the two orbifold planes, the "observable" sector, can have a low energy particle spectrum which is precisely the N = 1 super-symmetric standard model with three right-handed neutrino chiral supermultiplets. The other orbifold plane constitutes a "hidden" sector which, since its communication with the observable sector is suppressed, will be ignored in this paper. However, the finite fifth-dimension allows for the existence of three-brane solitons which, in order to render the vacuum anomaly free, must appear. That is, heterotic M -theory provides a natural framework for brane-world cosmological scenarios coupled to realistic particle physics. The complete worldvolume action of such three-branes is unknown. Here, treating these solitons as probe branes, we construct their scalar worldvolume Lagrangian as a derivative expansion of the heterotic DBI action. In analogy with similar calculations in the M 5 and AdS 5 context, this leads to the construction of "heterotic Galileons". However, realistic vacua of heterotic M -theory are necessarily N = 1 supersymmetric in four dimensions. Hence, we proceed to supersymmetrize the three-brane worldvolume action, first in flat superspace and then extend the results to N = 1 supergravity. Such a worldvolume action may lead to interesting cosmology, such as "bouncing" universe models, by allowing for the violation of the Null Energy Condition (NEC).

  2. Solutions of the Strominger System via Stable Bundles on Calabi-Yau Threefolds

    DEFF Research Database (Denmark)

    Andreas, Björn; Garcia Fernandez, Mario

    2012-01-01

    We prove that a given Calabi-Yau threefold with a stable holomorphic vector bundle can be perturbed to a solution of the Strominger system provided that the second Chern class of the vector bundle is equal to the second Chern class of the tangent bundle. If the Calabi-Yau threefold has strict SU(......) holonomy then the equations of motion derived from the heterotic string effective action are also satisfied by the solutions we obtain....

  3. CP violation and moduli stabilization in heterotic models

    International Nuclear Information System (INIS)

    Giedt, Joel

    2002-01-01

    The role of moduli stabilization in predictions for CP violation is examined in the context of four-dimensional effective supergravity models obtained from the weakly coupled heterotic string. They point out that while stabilization of compactification moduli has been studied extensively, the determination of background values for other scalar by dynamical means has not been subjected to the same degree of scrutiny. These other complex scalars are important potential sources of CP violation and they show in a simple model how their background values (including complex phases) may be determined from the minimization of the supergravity scalar potential, subject to the constraint of vanishing cosmological constant

  4. Consistent superstrings as solutions of the D=26 bosonic string theory

    International Nuclear Information System (INIS)

    Casher, A.; Englert, F.; Nicolai, H.; Taormina, A.

    1985-01-01

    Consistent closed ten-dimensional superstrings, i.e. the two N=2 superstrings, are contained in the 26-dimensional bosonic closed string theory. The latter thus appears as the fundamental string theory. (orig.)

  5. Anomalies and modular invariance in string theory

    International Nuclear Information System (INIS)

    Schellekens, A.N.; Warner, N.P.

    1986-01-01

    All known anomaly cancellations of heterotic string theories are derived directly from one-loop modular invariance, and are shown to be related to a property of modular functions of weight 2. Using modular invariance infinite classes of anomaly free field theories are constructed in (8m+2) dimensions for any m. A generating function is obtained for the anomalies of string-related field theories in (8m+2) dimensions. (orig.)

  6. A classification of open string models

    International Nuclear Information System (INIS)

    Nahm, W.

    1985-12-01

    Open string models are classified using modular invariance. No good candidates for new models are found, though the existence of an E 8 invariant model in Rsup(17,1), a similar one in Rsup(5,1) and of a supersymmetric model in Rsup(2,1) cannot be excluded by this technique. An intriguing relation between the left moving and right moving sectors of the heterotic string emerges. (orig.)

  7. Heterotic Mini-landscape in blow-up

    CERN Document Server

    Bizet, Nana Geraldine Cabo

    2013-01-01

    Localization properties of fields in compact extra dimensions are crucial ingredients for string model building, particularly in the framework of orbifold compactifications. Realistic models often require a slight deviation from the orbifold point, that can be analyzed using field theoretic methods considering (singlet) fields with nontrivial vacuum expectation values. Some of these fields correspond to blow-up modes that represent the resolution of orbifold singularities. Improving on previous analyses we give here an explicit example of the blow-up of a model from the heterotic Mini-landscape. An exact identification of the blow-up modes at various fixed points and fixed tori with orbifold twisted fields is given. We match the massless spectra and identify the blow-up modes as non-universal axions of compactified string theory. We stress the important role of the Green-Schwarz anomaly polynomial for the description of the resolution of orbifold singularities.

  8. Phenomenological aspects of heterotic orbifold models at one loop

    International Nuclear Information System (INIS)

    Birkedal-Hansen, A.; Binetruy, P.; Mambrini, Y.; Nelson, B.

    2003-01-01

    We provide a detailed study of the phenomenology of orbifold compactifications of the heterotic string within the context of supergravity effective theories. Our investigation focuses on those models where the soft Lagrangian is dominated by loop contributions to the various soft supersymmetry breaking parameters. Such models typically predict non-universal soft masses and are thus significantly different from minimal supergravity and other universal models. We consider the pattern of masses that are governed by these soft terms and investigate the implications of certain indirect constraints on supersymmetric models, such as flavor-changing neutral currents, the anomalous magnetic moment of the muon and the density of thermal relic neutralinos. These string-motivated models show novel behavior that interpolates between the phenomenology of unified supergravity models and models dominated by the superconformal anomaly

  9. EVH black hole solutions with higher derivative corrections

    International Nuclear Information System (INIS)

    Yavartanoo, Hossein

    2012-01-01

    We analyze the effect of higher derivative corrections to the near horizon geometry of the extremal vanishing horizon (EVH) black hole solutions in four dimensions. We restrict ourselves to a Gauss-Bonnet correction with a dilation dependent coupling in an Einstein-Maxwell-dilaton theory. This action may represent the effective action as it arises in tree level heterotic string theory compactified to four dimensions or the K3 compactification of type II string theory. We show that EVH black holes, in this theory, develop an AdS 3 throat in their near horizon geometry. (orig.)

  10. Magnetic strings

    International Nuclear Information System (INIS)

    Chaves, Max

    2006-01-01

    The conception of the magnetic string is presented as an infinitely thin bundle of magnetic flux lines. The magnetic strings are surrounded by a film of current that rotates around them, and are a solution of Maxwell's equations. The magnetic potential contains a line singularity, and its stability can be established topologically. A few comments are added on the possibility that they may exist at a cosmological scale as relics of the Big Bang. (author) [es

  11. Fayet-Iliopoulos D terms in string theory

    Energy Technology Data Exchange (ETDEWEB)

    Sen, A.

    1987-06-01

    One loop scalar masses induced by Fayet-Ilipoulos D terms in string theory are calculated directly in the heterotic string theory for an arbitrary compactification which preserves space-time supersymmetry at the string tree level. The result is shown to be a total derivative in the moduli space of a torus with two punctures, and hence receives contribution only from the boundary of this moduli space.

  12. Fayet-Iliopoulos D terms in string theory

    International Nuclear Information System (INIS)

    Sen, A.

    1987-06-01

    One loop scalar masses induced by Fayet-Ilipoulos D terms in string theory are calculated directly in the heterotic string theory for an arbitrary compactification which preserves space-time supersymmetry at the string tree level. The result is shown to be a total derivative in the moduli space of a torus with two punctures, and hence receives contribution only from the boundary of this moduli space

  13. Accidental symmetries and the effective Lagrangian of string theory

    International Nuclear Information System (INIS)

    Ovrut, B.A.

    1989-01-01

    In this paper the relationship between accidental worldsheet symmetries of the string generating functional and target space invariance groups is discussed. Accidental symmetries are used to derive the invariance groups and effective low energy Lagrangian for the bosonic string, and the heterotic string compactified to four-dimensions on Z N orbifolds. The necessity of a new type of Green-Schwarz mechanism, associated with the auxiliary vector field in the four-dimensional N = 1 supergravity multiplet, is shown using these methods

  14. Heterotic M-theory, warped geometry and the cosmological constant problem

    International Nuclear Information System (INIS)

    Krause, A.

    2001-01-01

    The first part of this thesis analyzes whether a locally flat background represents a stable vacuum for the proposed heterotic M-theory. A calculation of the leading order supergravity exchange diagrams leads to the conclusion that the locally flat vacuum cannot be stable. Afterwards a comparison with the corresponding weakly coupled heterotic string amplitudes is made. Next, we consider compactifications of heterotic M-theory on a Calabi-Yau threefold, including a non-vanishing G-flux. The ensuing warped-geometry is determined completely and used to show that the variation of the Calabi-Yau volume along the orbifold direction varies quadratically with distance instead linearly as suggested by an earlier first order approximation. In the second part of this thesis we propose a mechanism for obtaining a small cosmological constant. This mechanism consists of the separation of two domain-walls, which together constitute our world, up to a distance 2l ≅1/M GUT . The resulting warped-geometry leads to an exponential suppression of the cosmological constant, which thereby can obtain its observed value without introducing a large hierarchy. An embedding of this set-up into IIB string-theory entails an SU(6) grand unified theory with a natural explanation of the Higgs doublet-triplet splitting. Finally, we examine to what extent the string-theory T-duality can influence curvature. To this aim we derive the full transformation of the curvature-tensor under T-duality. (orig.)

  15. The superpotential in heterotic orbifold GUTs

    Energy Technology Data Exchange (ETDEWEB)

    Kappl, Rolf

    2011-12-08

    We study in this work the phenomenology of heterotic orbifold compactifications. Exact and approximate R symmetries of the superpotential in the context of supersymmetric field theories are discussed. We further study symmetries, phenomenological implications and Yukawa couplings from superpotential contributions in extra dimensional theories. We apply the developed methods to models, which base on heterotic orbifolds.

  16. String dualities and superpotential

    International Nuclear Information System (INIS)

    Ha, Tae-Won

    2010-09-01

    The main objective of this thesis is the computation of the superpotential induced by D5- branes in the type IIB string theory and by five-branes in the heterotic string theory. Both superpotentials have the same functional form which is the chain integral of the holomorphic three-form. Using relative (co)homology we can unify the flux and brane superpotential. The chain integral can be seen as an example of the Abel-Jacobi map. We discuss many structures such as mixed Hodge structure which allows for the computation of Picard-Fuchs differential equations crucial for explicit computations. We blow up the Calabi-Yau threefold along the submanifold wrapped by the brane to obtain geometrically more appropriate configuration. The resulting geometry is non-Calabi-Yau and we have a canonically given divisor. This blown-up geometry makes it possible to restrict our attention to complex structure deformations. However, the direct computation is yet very difficult, thus the main tool for computation will be the lift of the brane configuration to a F-theory compactification. In F-theory, since complex structure, brane and, if present, bundlemoduli are all contained in the complex structure moduli space of the elliptic Calabi-Yau fourfold, the computation can be dramatically simplified. The heterotic/F-theory duality is extended to include the blow-up geometry and thereby used to give the blow-up geometry amore physical meaning. (orig.)

  17. String dualities and superpotential

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Tae-Won

    2010-09-15

    The main objective of this thesis is the computation of the superpotential induced by D5- branes in the type IIB string theory and by five-branes in the heterotic string theory. Both superpotentials have the same functional form which is the chain integral of the holomorphic three-form. Using relative (co)homology we can unify the flux and brane superpotential. The chain integral can be seen as an example of the Abel-Jacobi map. We discuss many structures such as mixed Hodge structure which allows for the computation of Picard-Fuchs differential equations crucial for explicit computations. We blow up the Calabi-Yau threefold along the submanifold wrapped by the brane to obtain geometrically more appropriate configuration. The resulting geometry is non-Calabi-Yau and we have a canonically given divisor. This blown-up geometry makes it possible to restrict our attention to complex structure deformations. However, the direct computation is yet very difficult, thus the main tool for computation will be the lift of the brane configuration to a F-theory compactification. In F-theory, since complex structure, brane and, if present, bundlemoduli are all contained in the complex structure moduli space of the elliptic Calabi-Yau fourfold, the computation can be dramatically simplified. The heterotic/F-theory duality is extended to include the blow-up geometry and thereby used to give the blow-up geometry amore physical meaning. (orig.)

  18. Complex world-sheets from N=2 strings

    International Nuclear Information System (INIS)

    Barbon, J.L.F.

    1996-01-01

    We study some properties of target space strings constructed from (2,1) heterotic strings. We argue that world-sheet complexification is a general property of the bosonic sector of such target world-sheets. We give a target space interpretation of this fact and relate it to the non-gaussian nature of free string field theory. We provide several one-loop calculations supporting the stringy construction of critical world-sheets in terms of (2,1) models. Using finite-temperature boundary conditions in the underlying (2,1) string we obtain non-chiral target space spin structures, and point out some of the problems arising for chiral spin structures, such as the heterotic world-sheet. To this end, we study the torus partition function of the corresponding asymmetric orbifold of the (2,1) string. (orig.)

  19. Analytic solutions in the dyon black hole with a cosmic string: Scalar fields, Hawking radiation and energy flux

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, H.S., E-mail: horacio.santana.vieira@hotmail.com [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil); Centro de Ciências, Tecnologia e Saúde, Universidade Estadual da Paraíba, CEP 58233-000, Araruna, PB (Brazil); Bezerra, V.B., E-mail: valdir@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil); Silva, G.V., E-mail: gislainevs@hotmail.com [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, CEP 58051-970, João Pessoa, PB (Brazil)

    2015-11-15

    Charged massive scalar fields are considered in the gravitational and electromagnetic field produced by a dyonic black hole with a cosmic string along its axis of symmetry. Exact solutions of both angular and radial parts of the covariant Klein–Gordon equation in this background are obtained, and are given in terms of the confluent Heun functions. The role of the presence of the cosmic string in these solutions is showed up. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation spectrum and the energy flux. -- Highlights: •A cosmic string is introduced along the axis of symmetry of the dyonic black hole. •The covariant Klein–Gordon equation for a charged massive scalar field in this background is analyzed. •Both angular and radial parts are transformed to a confluent Heun equation. •The resulting Hawking radiation spectrum and the energy flux are obtained.

  20. Dynamical black holes in low-energy string theory

    Energy Technology Data Exchange (ETDEWEB)

    Aniceto, Pedro [Departamento de Matemática, Instituto Superior Técnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049 Lisboa (Portugal); Rocha, Jorge V. [Departament de Física Quàntica i Astrofísica, Institut de Ciències del Cosmos (ICCUB),Universitat de Barcelona,Martí i Franquès 1, E-08028 Barcelona (Spain)

    2017-05-08

    We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of dilaton-electrovacuum radiating solutions with a trivial axion, previously found by Güven and Yörük, is re-derived in a simpler manner and its causal structure is clarified. It is shown that such dynamical spacetimes featuring apparent horizons do not possess a regular light-like past null infinity or future null infinity, depending on whether they are radiating or accreting. These solutions are then extended in two ways. First we consider a Vaidya-like generalisation, which introduces a null dust source. Such spacetimes are used to test the status of cosmic censorship in the context of low-energy string theory. We prove that — within this family of solutions — regular black holes cannot evolve into naked singularities by accreting null dust, unless standard energy conditions are violated. Secondly, we employ S-duality to derive new time-dependent dyon solutions with a nontrivial axion turned on. Although they share the same causal structure as their Einstein-Maxwell-dilaton counterparts, these solutions possess both electric and magnetic charges.

  1. Heterotic/Type-II duality and its field theory avatars

    International Nuclear Information System (INIS)

    Kiritsis, Elias

    1999-01-01

    In these lecture notes, I will describe heterotic/type-II duality in six and four dimensions. When supersymmetry is the maximal N=4 it will be shown that the duality reduces in the field theory limit to the Montonen-Olive duality of N=4 Super Yang-Mills theory. We will consider further compactifications of type II theory on Calabi-Yau manifolds. We will understand the physical meaning of geometric conifold singularities and the dynamics of conifold transitions. When the CY manifold is a K3 fibration we will argue that the type-II ground-state is dual to the heterotic theory compactified on K3xT 2 . This allows an exact computation of the low effective action. Taking the field theory limit, α ' →0, we will recover the Seiberg-Witten non-perturbative solution of N=2 gauge theory

  2. Four-flux and warped heterotic M-theory compactifications

    International Nuclear Information System (INIS)

    Curio, Gottfried; Krause, Axel

    2001-01-01

    In the framework of heterotic M-theory compactified on a Calabi-Yau threefold 'times' an interval, the relation between geometry and four-flux is derived beyond first order. Besides the case with general flux which cannot be described by a warped geometry one is naturally led to consider two special types of four-flux in detail. One choice shows how the M-theory relation between warped geometry and flux reproduces the analogous one of the weakly coupled heterotic string with torsion. The other one leads to a quadratic dependence of the Calabi-Yau volume with respect to the orbifold direction which avoids the problem with negative volume of the first order approximation. As in the first order analysis we still find that Newton's constant is bounded from below at just the phenomenologically relevant value. However, the bound does not require an ad hoc truncation of the orbifold-size any longer. Finally we demonstrate explicitly that to leading order in κ 2/3 no Cosmological constant is induced in the four-dimensional low-energy action. This is in accord with what one can expect from supersymmetry

  3. De Sitter vacua from heterotic M-theory

    International Nuclear Information System (INIS)

    Becker, Melanie; Curio, Gottfried; Krause, Axel

    2004-01-01

    It is shown how metastable de Sitter vacua might arise from heterotic M-theory. The balancing of its two non-perturbative effects, open membrane instantons against gaugino condensation on the hidden boundary, which act with opposing forces on the interval length, is used to stabilize the orbifold modulus (dilaton) and other moduli. The non-perturbative effects break supersymmetry spontaneously through F-terms which leads to a positive vacuum energy density. In contrast to the situation for the weakly coupled heterotic string, the charged scalar matter fields receive non-vanishing vacuum expectation values and therefore masses in a phenomenologically relevant regime. It is important that in order to obtain these de Sitter vacua we are not relying on exotic effects or fine-tuning of parameters. Vacua with more realistic supersymmetry breaking scales and gravitino masses are obtained by breaking the hidden E 8 gauge group down to groups of smaller rank. Also small values for the open membrane instanton Pfaffian are favored in this respect. Finally we outline how the incorporation of additional flux superpotentials can be used to stabilize the remaining moduli

  4. Heterotic SO(32) model building in four dimensions

    International Nuclear Information System (INIS)

    Choi, K.S.; Groot Nibbelink, S.; Minnesota Univ., Minneapolis, MN; Trapletti, M.

    2004-10-01

    Four dimensional heterotic SO(32) orbifold models are classified systematically with model building applications in mind. We obtain all Z 3 , Z 7 and Z 2N models based on vectorial gauge shifts. The resulting gauge groups are reminiscent of those of type-I model building, as they always take the form SO(2n 0 ) x U(n 1 ) x.. x U(n N-1 ) x SO(2n N ). The complete twisted spectrum is determined simultaneously for all orbifold models in a parametric way depending on n 0 ,.., n N , rather than on a model by model basis. This reveals interesting patterns in the twisted states: They are always built out of vectors and anti-symmetric tensors of the U(n) groups, and either vectors or spinors of the SO(2n) groups. Our results may shed additional light on the S-duality between heterotic and type-I strings in four dimensions. As a spin-off we obtain an SO(10) GUT model with four generations from the Z 4 orbifold. (orig.)

  5. Vortex-like and string-like solutions for the 2+1 dimensional SU(2) Yang-Mills theory with the Chern-Simons term

    International Nuclear Information System (INIS)

    Teh, R.

    1989-07-01

    Vortex-like and string-like solutions of 2+1 Dim. SU(2) YM theory with the Chern-Simons term are discussed. Two ansatze are constructed which yield respectively analytic Bessel function solutions and elliptic function solutions. The Bessel function solutions are vortex-like and tend to the same vacuum state as the Ginzburg-Landau vortex solution at large ρ. The Jacobi elliptic function solutions are string-like, have finite energy and magnetic flux concentrated along a line in the x 1 - x 2 plane. (author). 18 refs

  6. From anomalies of finite symmetries to heterotic GUTs

    Science.gov (United States)

    Vaudrevange, Patrick K. S.

    2017-11-01

    We review the role of finite symmetries for particle physics with special emphasis on discrete anomalies and on their possible origin from extra dimensions. Then, we apply our knowledge on finite symmetries to the problematic proton decay operators of various mass-dimensions, focusing on ℤ4R , i.e. a special R-symmetry of order 4. We show that this ℤ4R symmetry can naturally originate from extra dimensions as a discrete remnant of higher-dimensional Lorentz symmetry. Finally, in order to obtain a unified picture from the heterotic string theory we discuss grand unified theories (GUTs) in extra dimensions compactified on ℤ2 × ℤ2 orbifolds and show how proton decay operators can be suppressed in a certain class of orbifolds.

  7. Heterotic free fermionic and symmetric toroidal orbifold models

    Energy Technology Data Exchange (ETDEWEB)

    Athanasopoulos, P.; Faraggi, A.E. [Department of Mathematical Sciences, University of Liverpool,Liverpool L69 7ZL (United Kingdom); Nibbelink, S. Groot [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München,80333 München (Germany); Mehta, V.M. [Institute for Theoretical Physics, University of Heidelberg,69120 Heidelberg (Germany)

    2016-04-07

    Free fermionic models and symmetric heterotic toroidal orbifolds both constitute exact backgrounds that can be used effectively for phenomenological explorations within string theory. Even though it is widely believed that for ℤ{sub 2}×ℤ{sub 2} orbifolds the two descriptions should be equivalent, a detailed dictionary between both formulations is still lacking. This paper aims to fill this gap: we give a detailed account of how the input data of both descriptions can be related to each other. In particular, we show that the generalized GSO phases of the free fermionic model correspond to generalized torsion phases used in orbifold model building. We illustrate our translation methods by providing free fermionic realizations for all ℤ{sub 2}×ℤ{sub 2} orbifold geometries in six dimensions.

  8. Heterotic Road to the MSSM with R parity

    CERN Document Server

    Lebedev, Oleg; Raby, Stuart; Ramos-Sanchez, Saul; Ratz, Michael; Vaudrevange, Patrick K S; Wingerter, Akin

    2008-01-01

    In a previous paper, referred to as a "Mini-Landscape" search, we explored a "fertile patch" of the heterotic landscape based on a Z6-II orbifold with SO(10) and E6 local GUT structures. In the present paper we extend this analysis. We find many models with the minimal supersymmetric standard model spectra and an exact R parity. In all of these models, the vector-like exotics decouple along D flat directions. We present two "benchmark" models which satisfy many of the constraints of a realistic supersymmetric model, including non-trivial Yukawa matrices for 3 families of quarks and leptons and Majorana neutrino masses for right-handed neutrinos with non-trivial See-Saw masses for the 3 light neutrinos. In an appendix we comment on the important issue of string selection rules and in particular the so-called "gamma-rule".

  9. Topics in string theory

    Science.gov (United States)

    Gorbatov, Elie

    In the first part of the dissertation we study noncommutative field theories at finite temperature. We find evidence for winding states and observe the existence of a transition to a new phase where there is a reduction of the degrees of freedom in the non-planar sector of the theory. We emphasize that such a transition is generic and insensitive to the particulars of the UV definition of the theory. In the second part we investigate some aspects of M-theory compactifications on orbifolds. The heterotic E8 x E 8 string compactified on T4/ ZN has gauge group G x G˜ with massless states in the twisted sector charged under both factors. In the dual M-theory description on T4/ ZN x S1/Z 2 the two groups do not communicate with each other since they reside on the boundary of the eleven dimensional spacetime. This leads to a conundrum for the twisted states of the perturbative heterotic string for there does not seem to be local degrees of freedom which carry charges under both G and G˜. We propose a resolution of this apparent paradox by nonperturbative states in M-theory. In support of our argument we review the consideration of six-dimensional gauge couplings and verify the local anomaly cancellation. In order to understand the dynamical properties of these states we deform the orbifold geometry, find an equivalent string theory background, and brane engineer the low energy six-dimensional field theories. In the process we encounter many exotic and surprising phenomena which are intrinsically M-theoretic and completely invisible to the perturbative observer.

  10. Cosmological solutions in string theory with dilaton self interaction potential; Soluciones cosmologicas en teoria de cuerdas con potencial de autointeraccion dilatonico

    Energy Technology Data Exchange (ETDEWEB)

    Mora, C. [Departamento de Matematicas, Unidad Profesional Interdisciplinaria de Biotecnologia, IPN, Av. Acueducto s/n Barrio La Laguna Ticoman, 07340 Mexico D.F. (Mexico)]. E-mail: cmora@acei.upibi.ipn.mx; Pimentel, L.O. [Departamento de Fisica, Universidad Autonoma Metropolitana-lztapalapa, A.P. 44-534, 09340Mexico, D.F. (Mexico)]. E-mail: lopr@xanum.uam.mx

    2003-07-01

    In this work we present homogeneous and isotropic cosmological solutions for the low energy limit of string theory with a self interacting potential for the scalar field. For a potential that is a linear combination of two exponential, a family of exact solutions are found for the different spatial curvatures. Among this family a non singular accelerating solution for positive curvature is singled out and the violation of the energy conditions for that solution is studied, and also its astrophysical consequences. The string coupling for this solution is finite. (Author)

  11. N=2 type II - heterotic duality and higher derivative F-terms

    International Nuclear Information System (INIS)

    Antoniadis, I.; Narain, K.S.; Taylor, T.R.

    1995-07-01

    We test the recently conjectured duality between N-2 supersymmetric type II and heterotic string models by analyzing a class of higher dimensional interactions in the respective low-energy Lagrangians. These are F-terms of the form F g W 2g where W is the gravitational superfield. On the type II side these terms are generated at the g-loop level and in fact are given by topological partition functions of the twisted Calabi-Yan sigma model. We show that on the heterotic side these terms arise at the one-loop level. We study in detail a rank 3 example and show that the corresponding couplings, F g satisfy the same holomorphic anomaly equations as in the type II case. Moreover we study the leading singularities of F g 's on the heterotic side, near the enhanced symmetry point and show that they are universal poles of order 2g - 2 with coefficients that are given by the Euler number of the moduli space of genus-g Riemann surfaces. This confirms a recent conjecture that the physics near the conifold singularity is governed by c=1 string theory at the self-dual point. (author). 24 refs

  12. Non-geometric five-branes in heterotic supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Shin; Yata, Masaya [Department of Physics, Kitasato University,Sagamihara 252-0373 (Japan); Department of Physics, National University of Singapore,2, Science Drive 3, Singapore 117542 (Singapore)

    2016-11-10

    We study T-duality chains of five-branes in heterotic supergravity where the first order α{sup ′}-corrections are present. By performing the α{sup ′}-corrected T-duality transformations of the heterotic NS5-brane solutions, we obtain the KK5-brane and the exotic 5{sub 2}{sup 2}-brane solutions associated with the symmetric, the neutral and the gauge NS5-branes. We find that the Yang-Mills gauge field in these solutions satisfies the self-duality condition in the three- and two-dimensional transverse spaces to the brane world-volumes. The O(2,2) monodromy structures of the 5{sub 2}{sup 2}-brane solutions are investigated by the α{sup ′}-corrected generalized metric. Our analysis shows that the symmetric 5{sub 2}{sup 2}-brane solution, which satisfies the standard embedding condition, is a T-fold and it exhibits the non-geometric nature. We also find that the neutral 5{sub 2}{sup 2}-brane solution is a T-fold at least at O(α{sup ′}). On the other hand, the gauge 5{sub 2}{sup 2}-brane solution is not a T-fold but show unusual structures of space-time.

  13. Two-loop string theory on null compactifications

    International Nuclear Information System (INIS)

    Cove, Henry C.D.; Szabo, Richard J.

    2006-01-01

    We compute the two-loop contributions to the free energy in the null compactification of perturbative string theory at finite temperature. The cases of bosonic, type II and heterotic strings are all treated. The calculation exploits an explicit reductive parametrization of the moduli space of infinite-momentum frame string worldsheets in terms of branched cover instantons. Various arithmetic and physical properties of the instanton sums are described. Applications to symmetric product orbifold conformal field theories and to the matrix string theory conjecture are also briefly discussed

  14. On heterotic vacua with fermionic expectation values

    Energy Technology Data Exchange (ETDEWEB)

    Minasian, Ruben [Institut de Physique Theorique, Universite Paris Saclay, CEA, CNRS, Gif-sur-Yvette (France); Petrini, Michela [Sorbonne Universites, CNRS, LPTHE, UPMC Paris 06, UMR 7589, Paris (France); Svanes, Eirik Eik [Sorbonne Universites, CNRS, LPTHE, UPMC Paris 06, UMR 7589, Paris (France); Sorbonne Universites, Institut Lagrange de Paris, Paris (France)

    2017-03-15

    We study heterotic backgrounds with non-trivial H-flux and non-vanishing expectation values of fermionic bilinears, often referred to as gaugino condensates. The gaugini appear in the low energy action via the gauge-invariant three-form bilinear Σ{sub MNP} = tr anti χΓ{sub MNP}χ. For Calabi-Yau compactifications to four dimensions, the gaugino condensate corresponds to an internal three-form Σ{sub mnp} that must be a singlet of the holonomy group. This condition does not hold anymore when an internal H-flux is turned on and O(α{sup '}) effects are included. In this paper we study flux compactifications to three and four-dimensions on G-structure manifolds. We derive the generic conditions for supersymmetric solutions. We use integrability conditions and Lichnerowicz type arguments to derive a set of constraints whose solution, together with supersymmetry, is sufficient for finding backgrounds with gaugino condensate. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Algebraic solutions in open string field theory – a lightning review

    Czech Academy of Sciences Publication Activity Database

    Schnabl, Martin

    2010-01-01

    Roč. 50, č. 3 (2010), s. 102-108 ISSN 1210-2709 Grant - others:EUROHORC(XE) EYI/07/E010 Institutional research plan: CEZ:AV0Z10100502 Keywords : string field theory * tachyon condensation Subject RIV: BF - Elementary Particles and High Energy Physics https://ojs.cvut.cz/ojs/index.php/ap/article/download/1213/1045

  16. Δ(54) flavor phenomenology and strings

    Energy Technology Data Exchange (ETDEWEB)

    Carballo-Pérez, Brenda [Instituto de Física, Universidad Nacional Autónoma de México,Apartado Postal 20-364, Ciudad de México 01000 (Mexico); HEBA Ideas S.A. de C.V.,Calculistas 37, Cd. Mx. 09400 (Mexico); Peinado, Eduardo; Ramos-Sánchez, Saúl [Instituto de Física, Universidad Nacional Autónoma de México,Apartado Postal 20-364, Ciudad de México 01000 (Mexico)

    2016-12-23

    Δ(54) can serve as a flavor symmetry in particle physics, but remains almost unexplored. We show that in a classification of semi-realistic ℤ{sub 3}×ℤ{sub 3} heterotic string orbifolds, Δ(54) turns out to be the most natural flavor symmetry, providing additional motivation for its study. We revisit its phenomenological potential from a low-energy perspective and subject to the constraints of string models. We find a model with Δ(54) arising from heterotic orbifolds that leads to the Gatto-Sartori-Tonin relation for quarks and charged-leptons. Additionally, in the neutrino sector, it leads to a normal hierarchy for neutrino masses and a correlation between the reactor and the atmospheric mixing angles, the latter taking values in the second octant and being compatible at three sigmas with experimental data.

  17. Light hidden-sector U(1)s in string compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Goodsell, Mark; Ringwald, Andreas

    2010-02-15

    We review the case for light U(1) gauge bosons in the hidden-sector of heterotic and type II string compactifications, present estimates of the size of their kinetic mixing with the visible-sector hypercharge U(1), and discuss their possibly very interesting phenomenological consequences in particle physics and cosmology. (orig.)

  18. Light hidden-sector U(1)s in string compactifications

    International Nuclear Information System (INIS)

    Goodsell, Mark; Ringwald, Andreas

    2010-02-01

    We review the case for light U(1) gauge bosons in the hidden-sector of heterotic and type II string compactifications, present estimates of the size of their kinetic mixing with the visible-sector hypercharge U(1), and discuss their possibly very interesting phenomenological consequences in particle physics and cosmology. (orig.)

  19. Exact solutions of the Schrödinger equation with a coulomb ring-shaped potential in the cosmic string spacetime

    Science.gov (United States)

    Wang, Zhi; Long, Zheng-wen; Long, Chao-yun; Teng, Jing

    2015-05-01

    We study the Schrödinger equation with a Coulomb ring-shaped potential in the spacetime of a cosmic string, and the solutions of the system are obtained by using the generalized parametric Nikiforov-Uvarov (NU) method. They show that the quantum dynamics of a physical system depend on the non-trivial topological features of the cosmic string spacetime and the energy levels of the considered quantum system depend explicitly on the angular deficit α which characterizes the global structure of the metric in the cosmic string spacetime.

  20. A note on flux induced superpotentials in string theory

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Melanie [Department of Physics, University of Maryland, College Park, MD 20742-4111 (United States)]. E-mail: melanieb@physics.umd.edu; Constantin, Dragos [Department of Physics, University of Maryland, College Park, MD 20742-4111 (United States)

    2003-08-01

    Non-vanishing fluxes in M-theory and string theory compactifications induce a superpotential in the lower dimensional theory. Gukov has conjectured the explicit form of this superpotential. We check this conjecture for the heterotic string compactified on a Calabi-Yau three-fold as well as for warped M-theory compactifications on Spin(7) holonomy manifolds, by performing a Kaluza-Klein reduction. (author)

  1. A note on flux induced superpotentials in string theory

    International Nuclear Information System (INIS)

    Becker, Melanie; Constantin, Dragos

    2003-01-01

    Non-vanishing fluxes in M-theory and string theory compactifications induce a superpotential in the lower dimensional theory. Gukov has conjectured the explicit form of this superpotential. We check this conjecture for the heterotic string compactified on a Calabi-Yau three-fold as well as for warped M-theory compactifications on Spin(7) holonomy manifolds, by performing a Kaluza-Klein reduction. (author)

  2. AdS3 xw (S3 x S3 x S1) solutions of type IIB string theory

    International Nuclear Information System (INIS)

    Donos, Aristomenis; Gauntlett, Jerome P.; Imperial College, London; Sparks, James

    2008-10-01

    We analyse a recently constructed class of local solutions of type IIB supergravity that consist of a warped product of AdS 3 with a sevendimensional internal space. In one duality frame the only other nonvanishing fields are the NS three-form and the dilaton. We analyse in detail how these local solutions can be extended to globally well-defined solutions of type IIB string theory, with the internal space having topology S 3 x S 3 x S 1 and with properly quantised three-form flux. We show that many of the dual (0,2) SCFTs are exactly marginal deformations of the (0,2) SCFTs whose holographic duals are warped products of AdS 3 with seven-dimensional manifolds of topology S 3 x S 2 x T 2 . (orig.)

  3. Connecting solutions in open string field theory with singular gauge transformations

    Czech Academy of Sciences Publication Activity Database

    Erler, Theodore; Maccaferri, C.

    2012-01-01

    Roč. 2012, č. 4 (2012), 1-40 ISSN 1126-6708 Grant - others:EUROHORC and ESF(XE) EYI/07/E010 Institutional research plan: CEZ:AV0Z10100502 Keywords : tachyon condensation * string field theory Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.618, year: 2012 http://link.springer.com/article/10.1007%2FJHEP04%282012%29107

  4. Field theory and strings

    International Nuclear Information System (INIS)

    Bonara, L.; Cotta-Ramusino, P.; Rinaldi, M.

    1987-01-01

    It is well-known that type I and heterotic superstring theories have a zero mass spectrum which correspond to the field content of N=1 supergravity theory coupled to supersymmetric Yang-Mills theory in 10-D. The authors study the field theory ''per se'', in the hope that simple consistency requirements will determine the theory completely once one knows the field content inherited from string theory. The simplest consistency requirements are: N=1 supersymmetry; and absence of chiral anomalies. This is what the authors discuss in this paper here leaving undetermined the question of the range of validity of the resulting field theory. As is known, a model of N=1 supergravity (SUGRA) coupled to supersymmetric Yang-Mills (SYM) theory was known in the form given by Chapline and Manton. The coupling of SUGRA to SYM was determined by the definition of the ''field strength'' 3-form H in this paper

  5. An ambiguity in fermionic string perturbation theory

    International Nuclear Information System (INIS)

    Atick, J.J.; Rabin, J.M.

    1988-01-01

    Recent investigation by Verlinde and Verlinde has shown that the fermionic string loop amplitudes change by a total derivative term in the moduli space under a change of basis of the supermoduli. This ambiguity is addressed in the context of the heterotic string theory, and shown to be a consequence of an inherent ambiguity in defining integration over the variables of a Grassmann algebra - in this case the Grassmann-valued coordinates of the supermoduli space. A resolution of this ambiguity in genus-two within this formalism is also presented. (orig.)

  6. BPS algebras, genus zero and the heterotic Monster

    Science.gov (United States)

    Paquette, Natalie M.; Persson, Daniel; Volpato, Roberto

    2017-10-01

    In this note, we expand on some technical issues raised in (Paquette et al 2016 Commun. Number Theory Phys. 10 433-526) by the authors, as well as providing a friendly introduction to and summary of our previous work. We construct a set of heterotic string compactifications to 0  +  1 dimensions intimately related to the Monstrous moonshine module of Frenkel, Lepowsky, and Meurman (and orbifolds thereof). Using this model, we review our physical interpretation of the genus zero property of Monstrous moonshine. Furthermore, we show that the space of (second-quantized) BPS-states forms a module over the Monstrous Lie algebras mg —some of the first and most prominent examples of Generalized Kac-Moody algebras—constructed by Borcherds and Carnahan. In particular, we clarify the structure of the module present in the second-quantized string theory. We also sketch a proof of our methods in the language of vertex operator algebras, for the interested mathematician.

  7. Integrals of periodic motion and periodic solutions for classical equations of relativistic string with masses at ends. I. Integrals of periodic motion

    International Nuclear Information System (INIS)

    Barbashov, B.M.

    1996-01-01

    Boundary equations for the relativistic string with masses at ends are formulated in terms of geometrical invariants of world trajectories of masses at the string ends. In the three-dimensional Minkowski space E 2 1 , there are two invariants of that sort, the curvature K and torsion κ. Curvatures of trajectories of the string ends with masses are always constant, K i =γ/m i (i=1,2), whereas torsions κ i obey a system of differential equations with deviating arguments. For these equations with periodic κ i (τ+nl)=κ(τ), constants of motion are obtained (part 1) and exact solutions are presented (part 2) for periods l and 2l where l is the string length in the plane of parameters τ and σ(σ 1 =0, σ 2 =l). 7 refs

  8. Supergravity duals of matrix string theory

    International Nuclear Information System (INIS)

    Morales, Jose F.; Samtleben, Henning

    2002-01-01

    We study holographic duals of type II and heterotic matrix string theories described by warped AdS 3 supergravities. By explicitly solving the linearized equations of motion around near horizon D-string geometries, we determine the spectrum of Kaluza-Klein primaries for type I, II supergravities on warped AdS 3 xS 7 . The results match those coming from the dual two-dimensional gauge theories living on the D-string worldvolumes. We briefly discuss the connections with the N=(8,8), N=(8,0) orbifold superconformal field theories to which type IIB/heterotic matrix strings flow in the infrared. In particular, we associate the dimension (h,h-bar) (32,32) twisted operator which brings the matrix string theories out from the conformal point (R; 8 ) N /S N with the dilaton profile in the supergravity background. The familiar dictionary between masses and 'scaling' dimensions of field and operators are modified by the presence of non-trivial warp factors and running dilatons. These modifications are worked out for the general case of domain wall/QFT correspondences between supergravities on warped AdS d+1 xS q geometries and super Yang-Mills theories with 16 supercharges. (author)

  9. Heterotic computing: past, present and future.

    Science.gov (United States)

    Kendon, Viv; Sebald, Angelika; Stepney, Susan

    2015-07-28

    We introduce and define 'heterotic computing' as a combination of two or more computational systems such that they provide an advantage over either substrate used separately. This first requires a definition of physical computation. We take the framework in Horsman et al. (Horsman et al. 2014 Proc. R. Soc. A 470, 20140182. (doi:10.1098/rspa.2014.0182)), now known as abstract-representation theory, then outline how to compose such computational systems. We use examples to illustrate the ubiquity of heterotic computing, and to discuss the issues raised when one or more of the substrates is not a conventional silicon-based computer. We briefly outline the requirements for a proper theoretical treatment of heterotic computational systems, and the advantages such a theory would provide. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  10. Persistent homology and string vacua

    Energy Technology Data Exchange (ETDEWEB)

    Cirafici, Michele [Center for Mathematical Analysis, Geometry and Dynamical Systems,Instituto Superior Técnico, Universidade de Lisboa,Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Institut des Hautes Études Scientifiques,Le Bois-Marie, 35 route de Chartres, F-91440 Bures-sur-Yvette (France)

    2016-03-08

    We use methods from topological data analysis to study the topological features of certain distributions of string vacua. Topological data analysis is a multi-scale approach used to analyze the topological features of a dataset by identifying which homological characteristics persist over a long range of scales. We apply these techniques in several contexts. We analyze N=2 vacua by focusing on certain distributions of Calabi-Yau varieties and Landau-Ginzburg models. We then turn to flux compactifications and discuss how we can use topological data analysis to extract physical information. Finally we apply these techniques to certain phenomenologically realistic heterotic models. We discuss the possibility of characterizing string vacua using the topological properties of their distributions.

  11. A rotating string

    International Nuclear Information System (INIS)

    Jensen, B.

    1993-06-01

    The author presents a global solution of Einstein's equations which represents a rotating cosmic string with a finite coreradius. The importance of pressure for the generation of closed timelike curves outside the coreregion of such strings is clearly displayed in this model due to the simplicity of the source. 10 refs

  12. Flat directions in left-right symmetric string derived models

    International Nuclear Information System (INIS)

    Cleaver, Gerald B.; Clements, David J.; Faraggi, Alon E.

    2002-01-01

    The only string models known to reproduce the minimal supersymmetric standard model in the low energy effective field theory are those constructed in the free fermionic formulation. We demonstrate the existence of quasirealistic free fermionic heterotic string models in which supersymmetric singlet flat directions do not exist. This raises the possibility that supersymmetry is broken perturbatively in such models by the one-loop Fayet-Iliopoulos term. We show, however, that supersymmetric flat directions that utilize vacuum expectation values of some non-Abelian fields in the massless string spectrum do exist in the model. We argue that hidden sector condensates lift the flat directions and break supersymmetry hierarchically

  13. Baryon string model

    International Nuclear Information System (INIS)

    Klimenko, S.V.; Kochin, V.N.; Plyushchaj, M.S.; Pron'ko, G.P.; Razumov, A.V.; Samarin, A.V.

    1985-01-01

    Partial solutions to classical equations of three-string motion are considered. Simplest solutions, when three-string center moving with high velocity, are co nsidered. Single-mode solutions are studied. Explicit form of their parametrization is obtained and three-string dynamics visualization is made. Means of graphic packet ''Atom'' were used for visualization. A set of processes for graphic representation of multiparametric functions is developed. Peculiarity of these processes is a wide class of functions, which are represented by parametric, coordinate and functional isolines

  14. String theory flux vacua on twisted tori and generalized complex geometry

    International Nuclear Information System (INIS)

    Andriot, David

    2010-01-01

    This thesis is devoted to the study of flux vacua of string theory, with the ten-dimensional space-time split into a four-dimensional maximally symmetric space-time, and a six-dimensional internal manifold M, taken to be a solv-manifold (twisted torus). Such vacua are of particular interest when trying to relate string theory to supersymmetric (SUSY) extensions of the standard model of particles, or to cosmological models. For SUSY solutions of type II supergravities, allowing for fluxes on M helps to solve the moduli problem. Then, a broader class of manifolds than just the Calabi-Yau can be considered for M, and a general characterization is given in terms of Generalized Complex Geometry: M has to be a Generalized Calabi-Yau (GCY). A subclass of solv-manifolds have been proven to be GCY, so we look for solutions with such M. To do so, we use an algorithmic resolution method. Then we focus on specific new solutions: those admitting an intermediate SU(2) structure. A transformation named the twist is then discussed. It relates solutions on torus to solutions on solv-manifolds. Working out constraints on the twist to generate solutions, we can relate known solutions, and find a new one. We also use the twist to relate flux vacua of heterotic string. Finally we consider ten-dimensional de Sitter solutions. Looking for such solutions is difficult, because of several problems among which the breaking of SUSY. We propose an Ansatz for SUSY breaking sources which helps to overcome these difficulties. We give an explicit solution on a solv-manifold, and discuss partially its four-dimensional stability. (author)

  15. Some properties of the product manifold of the solutions of string generated gravity models

    International Nuclear Information System (INIS)

    Ghika, G.

    1989-01-01

    Assuming that M 1 and M 2 are Einstein manifolds with M 2 compact and dim M 2 = n > 2 we show that the internal space M 2 is of constant curvature. If M 1 is flat and M 2 is Einstein then M 2 is also flat. We prove that if M 2 is spin, M 2 compact and A(M 2 )≠0 then R 1 must be negative. For n=4, M 2 Einstein and R 1 =0, the product of the gravitational constant and slope parameter is expressed by the Euler characteristic of M 2 divided by the integral over M 2 of the scalar curvature of M 2 . The model is then coupled to the dilaton field φ. In that case if M 1 is maximal symmetric, M 2 compact Einstein with n≥2, R 1 R 2 ≥0 and φ depends only on the variables of M 2 then on obtains the result that φ is constant and M 2 is flat. Other combinations of the second order in the curvatures arising from the bosonic and supersymmetric string theories are analyzed in the same global product case.(author)

  16. Charting the Landscape of Supercritical String Theory

    International Nuclear Information System (INIS)

    Hellerman, Simeon; Swanson, Ian

    2007-01-01

    Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions and different amounts of world sheet supersymmetry. These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories

  17. Comparative gene expression profiles between heterotic and non-heterotic hybrids of tetraploid Medicago sativa

    Directory of Open Access Journals (Sweden)

    Nettleton Dan

    2009-08-01

    Full Text Available Abstract Background Heterosis, the superior performance of hybrids relative to parents, has clear agricultural value, but its genetic control is unknown. Our objective was to test the hypotheses that hybrids expressing heterosis for biomass yield would show more gene expression levels that were different from midparental values and outside the range of parental values than hybrids that do not exhibit heterosis. Results We tested these hypotheses in three Medicago sativa (alfalfa genotypes and their three hybrids, two of which expressed heterosis for biomass yield and a third that did not, using Affymetrix M. truncatula GeneChip arrays. Alfalfa hybridized to approximately 47% of the M. truncatula probe sets. Probe set signal intensities were analyzed using MicroArray Suite v.5.0 (MAS and robust multi-array average (RMA algorithms. Based on MAS analysis, the two heterotic hybrids performed similarly, with about 27% of genes showing differential expression among the parents and their hybrid compared to 12.5% for the non-heterotic hybrid. At a false discovery rate of 0.15, 4.7% of differentially expressed genes in hybrids (~300 genes showed nonadditive expression compared to only 0.5% (16 genes in the non-heterotic hybrid. Of the nonadditively expressed genes, approximately 50% showed expression levels that fell outside the parental range in heterotic hybrids, but only one of 16 showed a similar profile in the non-heterotic hybrid. Genes whose expression differed in the parents were three times more likely to show nonadditive expression than genes whose parental transcript levels were equal. Conclusion The higher proportions of probe sets with expression level that differed from the parental midparent value and that were more extreme than either parental value in the heterotic hybrids compared to a non-heterotic hybrid were also found using RMA. We conclude that nonadditive expression of transcript levels may contribute to heterosis for biomass

  18. Higher-order blackhole solutions in N=2 supergravity and Calabi-Yau string backgrounds

    NARCIS (Netherlands)

    Behrndt, K.; Cardoso, G.L.; de Wit, B.Q.P.J.; Lüst, D.; Mohaupt, T.; Sabra, W.A.

    1998-01-01

    Based on special geometry, we consider corrections to N=2 extremal black-hole solutions and their entropies originating from higher-order derivative terms in N=2 supergravity. These corrections are described by a holomorphic function, and the higher-order black-hole solutions can be expressed in

  19. Cosmic string solution in a Born-Infeld type theory of gravity

    International Nuclear Information System (INIS)

    Rocha, W.J. da; Guimaraes, M.E.X.

    2009-01-01

    Full text. Advances in the formal structure of string theory point to the emergence, and necessity, of a scalar-tensorial theory of gravity. It seems that, at least at high energy scales, the Einstein's theory is not enough to explain the gravitational phenomena. In other words, the existence of a scalar (gravitational) field acting as a mediator of the gravitational interaction together with the usual purely rank-2 tensorial field is, indeed, a natural prediction of unification models as supergravity, superstrings and M-theory. This type of modified gravitation was first introduced in a different context in the 60's in order to incorporate the Mach's principle into relativity, but nowadays it acquired different sense in cosmology and gravity theories. Although such unification theories are the most acceptable, they all exist in higher dimensional spaces. The compactification from these higher dimensions to the 4-dimensional physics is not unique and there exist many effective theories of gravity which come from the unification process. Each of them must, of course, satisfy some predictions. Here, in this paper, we will deal with one of them. The so-called NDL theory. One important assumption in General Relativity is that all field interact in the same way with gravity. This is the so called Strong Equivalence Principle (SEP). It is well known, with good accuracy, that this is true when we concern with matter to matter interaction, i.e, the Weak Equivalence Principle(WEP) is tested. But, until now, there is no direct observational confirmation of this affirmation to the gravity to gravity interaction. In an extension of the field theoretical description of General Relativity constructed by is used to propose an alternative field theory of gravity. In this theory gravitons propagate in a different spacetime. The velocity of propagation of the gravitational waves in this theory does not coincide with the General Relativity predictions. (author)

  20. Splitting strings on integrable backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Vicedo, Benoit

    2011-05-15

    We use integrability to construct the general classical splitting string solution on R x S{sup 3}. Namely, given any incoming string solution satisfying a necessary self-intersection property at some given instant in time, we use the integrability of the worldsheet {sigma}-model to construct the pair of outgoing strings resulting from a split. The solution for each outgoing string is expressed recursively through a sequence of dressing transformations, the parameters of which are determined by the solutions to Birkhoff factorization problems in an appropriate real form of the loop group of SL{sub 2}(C). (orig.)

  1. String theory of Calabi-Yau compactifications

    International Nuclear Information System (INIS)

    Luetken, C.A.

    1989-01-01

    The conformal field theory description of Calabi-Yau compactifications of the heterotic superstring from 10 to 4 dimensions is outlined. The basic ideas of ordinary (bosonic) conformal field theory are explained before describing the exactly solvable N=2 superconformal minimal models which are needed in the tensor construction of certain particularly simple string vacua. Using a simple sigma-model construction of algebraic varieties and drawing on insight gained from the Landau-Ginzburg description of critical phenomena, it is explained how the critical behaviour of these 2-dimensional solvable quantum field theories with complex supersymmetry may be regarded as string compactification on a Calabi-Yau background. The virtue of this is to provide a tool for computing exact (tree level) results for strings in these highly non-trivial vacua, including all the Yukawa couplings needed in the construction of the low-energy effective field theory. (orig.)

  2. Heterotic computing: exploiting hybrid computational devices.

    Science.gov (United States)

    Kendon, Viv; Sebald, Angelika; Stepney, Susan

    2015-07-28

    Current computational theory deals almost exclusively with single models: classical, neural, analogue, quantum, etc. In practice, researchers use ad hoc combinations, realizing only recently that they can be fundamentally more powerful than the individual parts. A Theo Murphy meeting brought together theorists and practitioners of various types of computing, to engage in combining the individual strengths to produce powerful new heterotic devices. 'Heterotic computing' is defined as a combination of two or more computational systems such that they provide an advantage over either substrate used separately. This post-meeting collection of articles provides a wide-ranging survey of the state of the art in diverse computational paradigms, together with reflections on their future combination into powerful and practical applications. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. Construction of closed fermionic string models in four dimensions

    International Nuclear Information System (INIS)

    Lewellen, D.C.

    1987-01-01

    It is possible to construct consistent closed string models directly in four space-time dimensions if reparametrization invariance, conformal invariance and world sheet supersymmetry are properly accounted for. In the context of string models whose internal degrees of freedom are represented by free world sheet fermions, it is possible to completely solve for the above requirements, providing a simple set of rules for constructing string models. N = 1 supersymmetric and non-supersymmetric heterotic type string models with chiral fermions and realistic gauge groups, as well as generalized type II models with realistic gauge groups, can easily be constructed. Many other string models can be constructed using similar methods based on free world sheet bosons

  4. String theory

    International Nuclear Information System (INIS)

    Chan Hongmo.

    1987-10-01

    The paper traces the development of the String Theory, and was presented at Professor Sir Rudolf Peierls' 80sup(th) Birthday Symposium. The String theory is discussed with respect to the interaction of strings, the inclusion of both gauge theory and gravitation, inconsistencies in the theory, and the role of space-time. The physical principles underlying string theory are also outlined. (U.K.)

  5. String derived exophobic SU(6)×SU(2) GUTs

    International Nuclear Information System (INIS)

    Bernard, Laura; Faraggi, Alon E.; Glasser, Ivan; Rizos, John; Sonmez, Hasan

    2013-01-01

    With the apparent discovery of the Higgs boson, the Standard Model has been confirmed as the theory accounting for all sub-atomic phenomena. This observation lends further credence to the perturbative unification in Grand Unified Theories (GUTs) and string theories. The free fermionic formalism yielded fertile ground for the construction of quasi-realistic heterotic-string models, which correspond to toroidal Z 2 ×Z 2 orbifold compactifications. In this paper we study a new class of heterotic-string models in which the GUT group is SU(6)×SU(2) at the string level. We use our recently developed fishing algorithm to extract an example of a three generation SU(6)×SU(2) GUT model. We explore the phenomenology of the model and show that it contains the required symmetry breaking Higgs representations. We show that the model admits flat directions that produce a Yukawa coupling for a single family. The novel feature of the SU(6)×SU(2) string GUT models is that they produce an additional family universal anomaly free U(1) symmetry, and may remain unbroken below the string scale. The massless spectrum of the model is free of exotic states.

  6. Super string field theory and the Wess-Zumino-Witten action

    Czech Academy of Sciences Publication Activity Database

    Erler, Theodore

    2017-01-01

    Roč. 2017, č. 10 (2017), s. 1-63, č. článku 057. ISSN 1029-8479 R&D Projects: GA MŠk EF15_003/0000437 Institutional support: RVO:68378271 Keywords : string field theory * superstrings and heterotic strings Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 6.063, year: 2016

  7. Renormalization-group flows and charge transmutation in string theory

    International Nuclear Information System (INIS)

    Orlando, D.; Petropoulos, P.M.; Sfetsos, K.

    2006-01-01

    We analyze the behaviour of heterotic squashed-Wess-Zumino-Witten backgrounds under renormalization-group flow. The flows we consider are driven by perturbation creating extra gauge fluxes. We show how the conformal point acts as an attractor from both the target-space and world-sheet points of view. We also address the question of instabilities created by the presence of closed time-like curves in string backgrounds. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. The strings connection: MSSM-like models from strings

    Energy Technology Data Exchange (ETDEWEB)

    Nilles, Hans Peter [Bethe Center for Theoretical Physics (BCTP) and Physikalisches Institut der Universitaet Bonn, Bonn (Germany)

    2014-05-15

    String theory constructions towards the MSSM allow us to identify some general properties that could be relevant for tests at the LHC. They originate from the geometric structure of compactification and the location of fields in extra-dimensional space. Within the framework of the heterotic MiniLandscape we extract some generic lessons for supersymmetric model building. Among them is a specific pattern of SUSY breakdown based on mirage mediation and remnants of extended supersymmetry. This leads to a split spectrum with heavy scalars of the first two families of quarks and leptons and suppressed masses for gauginos, top partners and Higgs bosons. The models exhibit some specific form of hidden supersymmetry consistent with the high mass of the Higgs boson and all presently available experimental constraints. The most compelling picture is based on precision gauge coupling unification that might be in the kinematic reach of the LHC. (orig.)

  9. Quantum supergravity, supergravity anomalies and string phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, Mary K., E-mail: mkgaillard@lbl.gov

    2016-11-15

    I discuss the role of quantum effects in the phenomenology of effective supergravity theories from compactification of the weakly coupled heterotic string. An accurate incorporation of these effects requires a regularization procedure that respects local supersymmetry and BRST invariance and that retains information associated with the cut-off scale, which has physical meaning in an effective theory. I briefly outline the Pauli–Villars regularization procedure, describe some applications, and comment on what remains to be done to fully define the effective quantum field theory.

  10. Automorphic Forms and Mock Modular Forms in String Theory

    Science.gov (United States)

    Nazaroglu, Caner

    We study a variety of modular invariant objects in relation to string theory. First, we focus on Jacobi forms over generic rank lattices and Siegel forms that appear in N = 2, D = 4 compactifications of heterotic string with Wilson lines. Constraints from low energy spectrum and modularity are employed to deduce the relevant supersymmetric partition functions entirely. This procedure is applied on models that lead to Jacobi forms of index 3, 4, 5 as well as Jacobi forms over root lattices A2 and A3. These computations are then checked against an explicit orbifold model which can be Higgsed to the models under question. Models with a single Wilson line are then studied in detail with their relation to paramodular group Gammam as T-duality group made explicit. These results on the heterotic string side are then turned into predictions for geometric invariants using TypeII - Heterotic duality. Secondly, we study theta functions for indenite signature lattices of generic signature. Building on results in literature for signature (n-1,1) and (n-2,2) lattices, we work out the properties of generalized error functions which we call r-tuple error functions. We then use these functions to build such indenite theta functions and describe their modular completions.

  11. Heterotic quantum and classical computing on convergence spaces

    Science.gov (United States)

    Patten, D. R.; Jakel, D. W.; Irwin, R. J.; Blair, H. A.

    2015-05-01

    Category-theoretic characterizations of heterotic models of computation, introduced by Stepney et al., combine computational models such as classical/quantum, digital/analog, synchronous/asynchronous, etc. to obtain increased computational power. A highly informative classical/quantum heterotic model of computation is represented by Abramsky's simple sequential imperative quantum programming language which extends the classical simple imperative programming language to encompass quantum computation. The mathematical (denotational) semantics of this classical language serves as a basic foundation upon which formal verification methods can be developed. We present a more comprehensive heterotic classical/quantum model of computation based on heterotic dynamical systems on convergence spaces. Convergence spaces subsume topological spaces but admit finer structure from which, in prior work, we obtained differential calculi in the cartesian closed category of convergence spaces allowing us to define heterotic dynamical systems, given by coupled systems of first order differential equations whose variables are functions from the reals to convergence spaces.

  12. Giant magnon solution and dispersion relation in string theory in AdS3×S3×T4 with mixed flux

    International Nuclear Information System (INIS)

    Hoare, B.; Stepanchuk, A.; Tseytlin, A.A.

    2014-01-01

    We address the question of the exact form of the dispersion relation for light-cone string excitations in string theory in AdS 3 ×S 3 ×T 4 with mixed R–R and NS–NS 3-form fluxes. The analogy with string theory in AdS 5 ×S 5 suggests that in addition to the data provided by the perturbative near-BMN expansion and symmetry algebra considerations there is another source of information for the dispersion relation – the semiclassical giant magnon solution. In earlier work in (arXiv:1303.1037) and (arXiv:1304.4099) we found that the symmetry algebra constraints, which are consistent with a perturbative expansion, do not completely determine the form of the dispersion relation. The aim of the present paper is to fix the dispersion relation by constructing a generalisation of the known dyonic giant magnon soliton on S 3 to the presence of a non-zero NS–NS flux described by a WZ term in the string action (with coefficient q). We find that the angular momentum of this soliton gets shifted by a term linear in world-sheet momentum p. We also discuss the symmetry algebra of the string light-cone S-matrix and show that the exact dispersion relation, which should have the correct perturbative BMN and semiclassical giant magnon limits, should also contain such a linear momentum term. The simplicity of the resulting bound-state picture provides a strong argument in favour of this dispersion relation

  13. String flipped SO(10) model from Z4 orbifold

    International Nuclear Information System (INIS)

    Sato, H.; Shimojo, M.

    1993-01-01

    We search all possible string grand-unified-theory models obtained from heterotic superstrings compactified on a Z 4 orbifold with one Wilson line. It is shown that there is an essentially unique anomaly-free flipped SO(10) model with three generations plus one mirror conjugate generation of matter fields. We derive effective Yukawa interactions and examine the structure of mass matrices as well as a possible scenario of string coupling unification. The four-generation Z 4 orbifold model is a phenomenologically viable model beyond the minimal supersymmetric standard one

  14. Searching for the standard model in the string landscape: SUSY GUTs

    Science.gov (United States)

    Raby, Stuart

    2011-03-01

    The standard model is the theory describing all observational data from the highest energies to the largest distances. (There is, however, one caveat: additional forms of energy, not part of the standard model, known as dark matter and dark energy must be included in order to describe the Universe at galactic scales and larger.) High energies refers to physics at the highest energy particle accelerators, including CERN's LEP II (which ceased operation in 2000 to begin construction of the Large Hadron Collider now in operation) and Fermilab's Tevatron, as well as to the energies obtained in particle jets created in so-called active galactic nuclei scattered throughout the visible Universe. Some of these extra-galactic particles bombard our own Earth in the form of cosmic rays, or super-energetic protons which scatter off nucei in the upper atmosphere. String theory is, on the other hand, an unfinished theoretical construct which attempts to describe all matter and their interactions in terms of the harmonic oscillations of open and/or closed strings. It is regarded as unfinished since at present it is a collection of ideas, tied together by powerful consistency conditions, called dualities, with the ultimate goal of finding the completed string theory. At the moment we only have descriptions which are valid in different mutually exclusive limits with names such as type I, IIA, IIB, heterotic, M and F theory. The string landscape has been described in the pages of many scholarly and popular works. It is perhaps best understood as the collection of possible solutions to the string equations; albeit these solutions look totally different in the different limiting descriptions. What do we know about the string landscape? We know that there are such a large number of possible solutions that the only way to represent this number is as 10500 or a 1 followed by 500 zeros. Note that this is not a precise value since the uncertainty is given by a number just as large

  15. Searching for the standard model in the string landscape: SUSY GUTs

    International Nuclear Information System (INIS)

    Raby, Stuart

    2011-01-01

    The standard model is the theory describing all observational data from the highest energies to the largest distances. (There is, however, one caveat: additional forms of energy, not part of the standard model, known as dark matter and dark energy must be included in order to describe the Universe at galactic scales and larger.) High energies refers to physics at the highest energy particle accelerators, including CERN's LEP II (which ceased operation in 2000 to begin construction of the Large Hadron Collider now in operation) and Fermilab's Tevatron, as well as to the energies obtained in particle jets created in so-called active galactic nuclei scattered throughout the visible Universe. Some of these extra-galactic particles bombard our own Earth in the form of cosmic rays, or super-energetic protons which scatter off nucei in the upper atmosphere. String theory is, on the other hand, an unfinished theoretical construct which attempts to describe all matter and their interactions in terms of the harmonic oscillations of open and/or closed strings. It is regarded as unfinished since at present it is a collection of ideas, tied together by powerful consistency conditions, called dualities, with the ultimate goal of finding the completed string theory. At the moment we only have descriptions which are valid in different mutually exclusive limits with names such as type I, IIA, IIB, heterotic, M and F theory. The string landscape has been described in the pages of many scholarly and popular works. It is perhaps best understood as the collection of possible solutions to the string equations; albeit these solutions look totally different in the different limiting descriptions. What do we know about the string landscape? We know that there are such a large number of possible solutions that the only way to represent this number is as 10 500 or a 1 followed by 500 zeros. Note that this is not a precise value since the uncertainty is given by a number just as large

  16. Bowed Strings

    Science.gov (United States)

    Rossing, Thomas D.; Hanson, Roger J.

    In the next eight chapters, we consider some aspects of the science of bowed string instruments, old and new. In this chapter, we present a brief discussion of bowed strings, a subject that will be developed much more thoroughly in Chap. 16. Chapters 13-15 discuss the violin, the cello, and the double bass. Chapter 17 discusses viols and other historic string instruments, and Chap. 18 discusses the Hutchins-Schelleng violin octet.

  17. String theory compactifications

    CERN Document Server

    Graña, Mariana

    2017-01-01

    The lectures in this book provide graduate students and non-specialist researchers with a concise introduction to the concepts and formalism required to reduce the ten-dimensional string theories to the observable four-dimensional space-time - a procedure called string compactification. The text starts with a very brief introduction to string theory, first working out its massless spectrum and showing how the condition on the number of dimensions arises. It then dwells on the different possible internal manifolds, from the simplest to the most relevant phenomenologically, thereby showing that the most elegant description is through an extension of ordinary Riemannian geometry termed generalized geometry, which was first introduced by Hitchin. Last but not least, the authors review open problems in string phenomenology, such as the embedding of the Standard Model and obtaining de Sitter solutions.

  18. The operator formalism and contact terms in string theory

    International Nuclear Information System (INIS)

    Doyle, M.D.

    1992-01-01

    The operator formalism has proven to be a powerful tool in string theory. In particular, by making explicit the role of a choice of local coordinates (or, equivalently, a normal-ordering prescription) at vertex operator insertions, it provides a framework for understanding the insertion of very general states in both on-shell string theory and string field theory, for formulating a semirigid N = 2 geometry-based approach to topological gravity, for resolving ambiguities in fermionic string theory, and for analyzing contact interactions. The main focus of this thesis on this last application of the operator formalism, although it touches on each of the others. The first goal is the analysis of the dilaton contact terms required for the dilaton equation in the bosonic and heterotic strings. In the bosonic case, a coordinate family appropriate for a punctured sphere is given and is used to calculate dilaton two-point functions. This coordinate family is later generalized to a 'good' coordinate family appropriate for dilaton calculations on higher genus surfaces. It is found that dilaton-dilaton contact terms are improperly normalized resulting in the failure of the dilaton equation, suggesting that the zero-momentum dilaton is not the string coupling constant. This seems to be the result of a tachyon divergence. A similar calculation in the heterotic case, where there is no tachyon, shows that the dilaton contact terms are properly normalized, and that the dilaton equation and the interpretation of the dilaton as the string coupling constant goes through. The other major goal is re-examination of Green and Seiberg's work which showed that, in simple treatments of fermionic string theory, it is necessary to introduce contact interactions when vertex operators collide to avoid the failure of certain superconformal Ward identities

  19. Marginal deformations of heterotic G 2 sigma models

    Science.gov (United States)

    Fiset, Marc-Antoine; Quigley, Callum; Svanes, Eirik Eik

    2018-02-01

    Recently, the infinitesimal moduli space of heterotic G 2 compactifications was described in supergravity and related to the cohomology of a target space differential. In this paper we identify the marginal deformations of the corresponding heterotic nonlinear sigma model with cohomology classes of a worldsheet BRST operator. This BRST operator is nilpotent if and only if the target space geometry satisfies the heterotic supersymmetry conditions. We relate this to the supergravity approach by showing that the corresponding cohomologies are indeed isomorphic. We work at tree-level in α' perturbation theory and study general geometries, in particular with non-vanishing torsion.

  20. Perturbative string thermodynamics near black hole horizons

    International Nuclear Information System (INIS)

    Mertens, Thomas G.; Verschelde, Henri; Zakharov, Valentin I.

    2015-01-01

    We provide further computations and ideas to the problem of near-Hagedorn string thermodynamics near (uncharged) black hole horizons, building upon our earlier work http://dx.doi.org/10.1007/JHEP03(2014)086. The relevance of long strings to one-loop black hole thermodynamics is emphasized. We then provide an argument in favor of the absence of α ′ -corrections for the (quadratic) heterotic thermal scalar action in Rindler space. We also compute the large k limit of the cigar orbifold partition functions (for both bosonic and type II superstrings) which allows a better comparison between the flat cones and the cigar cones. A discussion is made on the general McClain-Roth-O’Brien-Tan theorem and on the fact that different torus embeddings lead to different aspects of string thermodynamics. The black hole/string correspondence principle for the 2d black hole is discussed in terms of the thermal scalar. Finally, we present an argument to deal with arbitrary higher genus partition functions, suggesting the breakdown of string perturbation theory (in g s ) to compute thermodynamical quantities in black hole spacetimes.

  1. Bosonic strings

    CERN Document Server

    Jost, Jürgen

    2007-01-01

    This book presents a mathematical treatment of Bosonic string theory from the point of view of global geometry. As motivation, Jost presents the theory of point particles and Feynman path integrals. He provides detailed background material, including the geometry of Teichmüller space, the conformal and complex geometry of Riemann surfaces, and the subtleties of boundary regularity questions. The high point is the description of the partition function for Bosonic strings as a finite-dimensional integral over a moduli space of Riemann surfaces. Jost concludes with some topics related to open and closed strings and D-branes. Bosonic Strings is suitable for graduate students and researchers interested in the mathematics underlying string theory.

  2. Effective action of heterotic compactification on K3 with non-trivial gauge bundles

    International Nuclear Information System (INIS)

    Schasny, Martin

    2012-10-01

    In this thesis we study the heterotic string compactified on K3 with non-trivial gauge bundles. We focus on two backgrounds, the well-known standard embedding and abelian line bundles. Using a Kaluza-Klein reduction, the six-dimensional effective action is computed up to terms of order α' 2 with special attention on the hypermultiplet sector. We compute the moduli dependent couplings of the matter fields and analyze the geometry of the hyperscalar sigma model. Moreover, we prove the consistency with six-dimensional supergravity and derive the appropriate D-term scalar potential. For the line bundle backgrounds we show that the gauge flux stabilizes some geometrical moduli and renders some abelian vector multiplets massive.

  3. Heterotic non-linear sigma models with anti-de Sitter target spaces

    International Nuclear Information System (INIS)

    Michalogiorgakis, Georgios; Gubser, Steven S.

    2006-01-01

    We calculate the beta function of non-linear sigma models with S D+1 and AdS D+1 target spaces in a 1/D expansion up to order 1/D 2 and to all orders in α ' . This beta function encodes partial information about the spacetime effective action for the heterotic string to all orders in α ' . We argue that a zero of the beta function, corresponding to a worldsheet CFT with AdS D+1 target space, arises from competition between the one-loop and higher-loop terms, similarly to the bosonic and supersymmetric cases studied previously in [J.J. Friess, S.S. Gubser, Non-linear sigma models with anti-de Sitter target spaces, Nucl. Phys. B 750 (2006) 111-141]. Various critical exponents of the non-linear sigma model are calculated, and checks of the calculation are presented

  4. Effective action of heterotic compactification on K3 with non-trivial gauge bundles

    Energy Technology Data Exchange (ETDEWEB)

    Schasny, Martin

    2012-10-15

    In this thesis we study the heterotic string compactified on K3 with non-trivial gauge bundles. We focus on two backgrounds, the well-known standard embedding and abelian line bundles. Using a Kaluza-Klein reduction, the six-dimensional effective action is computed up to terms of order {alpha}'{sup 2} with special attention on the hypermultiplet sector. We compute the moduli dependent couplings of the matter fields and analyze the geometry of the hyperscalar sigma model. Moreover, we prove the consistency with six-dimensional supergravity and derive the appropriate D-term scalar potential. For the line bundle backgrounds we show that the gauge flux stabilizes some geometrical moduli and renders some abelian vector multiplets massive.

  5. Perspectives on string phenomenology

    CERN Document Server

    Kane, Gordon; Kumar, Piyush

    2015-01-01

    The remarkable recent discovery of the Higgs boson at the CERN Large Hadron Collider completed the Standard Model of particle physics and has paved the way for understanding the physics which may lie beyond it. String/M theory has emerged as a broad framework for describing a plethora of diverse physical systems, which includes condensed matter systems, gravitational systems as well as elementary particle physics interactions. If string/M theory is to be considered as a candidate theory of Nature, it must contain an effectively four-dimensional universe among its solutions that is indistinguishable from our own. In these solutions, the extra dimensions of string/M Theory are “compactified” on tiny scales which are often comparable to the Planck length. String phenomenology is the branch of string/M theory that studies such solutions, relates their properties to data, and aims to answer many of the outstanding questions of particle physics beyond the Standard Model. This book contains perspectives on stri...

  6. Open problems in string cosmology

    International Nuclear Information System (INIS)

    Toumbas, N.

    2010-01-01

    Some of the open problems in string cosmology are highlighted within the context of the recently constructed thermal and quantum superstring cosmological solutions. Emphasis is given on the high temperature cosmological regime, where it is argued that thermal string vacua in the presence of gravito-magnetic fluxes can be used to bypass the Hagedorn instabilities of string gas cosmology. This article is based on a talk given at the workshop on ''Cosmology and Strings'', Corfu, September 6-13, 2009. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Vacuum strings in FRW models

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, C C; Oattes, L M; Starkman, G D

    1988-01-01

    The authors find that vacuum string solutions cannot be embedded in an FRW model in the spirit of the swiss cheese model for inhomogeneities. Since all standard lensing calculations rely implicitly on the Swiss Cheese model, this result indicates that the previous lensing results for the vacuum string may be in error.

  8. Towards optimal packed string matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany

    2014-01-01

    -size string-matching instruction wssm is available in contemporary commodity processors. The other word-size maximum-suffix instruction wslm is only required during the pattern pre-processing. Benchmarks show that our solution can be efficiently implemented, unlike some prior theoretical packed string...

  9. Comparing double string theory actions

    International Nuclear Information System (INIS)

    De Angelis, L.; Gionti, S.J.G.; Marotta, R.; Pezzella, F.

    2014-01-01

    Aimed to a deeper comprehension of a manifestly T-dual invariant formulation of string theory, in this paper a detailed comparison between the non-covariant action proposed by Tseytlin and the covariant one proposed by Hull is done. These are obtained by making both the string coordinates and their duals explicitly appear, on the same footing, in the world-sheet action, so “doubling” the string coordinates along the compact dimensions. After a discussion on the nature of the constraints in both the models and the relative quantization, it results that the string coordinates and their duals behave like “non-commuting” phase space coordinates but their expressions in terms of Fourier modes generate the oscillator algebra of the standard bosonic string. A proof of the equivalence of the two formulations is given. Furthermore, open-string solutions are also discussed

  10. Comparing double string theory actions

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, L. [Dipartimento di Fisica, Università degli Studi “Federico II” di Napoli,Complesso Universitario Monte S. Angelo ed. 6, via Cintia, 80126 Napoli (Italy); Gionti, S.J.G. [Specola Vaticana, Vatican City, V-00120, Vatican City State and Vatican Observatory Research Group, Steward Observatory, The University Of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721 (United States); Marotta, R.; Pezzella, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Napoli,Complesso Universitario di Monte S. Angelo ed. 6, via Cintia, 80126 Napoli (Italy)

    2014-04-28

    Aimed to a deeper comprehension of a manifestly T-dual invariant formulation of string theory, in this paper a detailed comparison between the non-covariant action proposed by Tseytlin and the covariant one proposed by Hull is done. These are obtained by making both the string coordinates and their duals explicitly appear, on the same footing, in the world-sheet action, so “doubling” the string coordinates along the compact dimensions. After a discussion on the nature of the constraints in both the models and the relative quantization, it results that the string coordinates and their duals behave like “non-commuting” phase space coordinates but their expressions in terms of Fourier modes generate the oscillator algebra of the standard bosonic string. A proof of the equivalence of the two formulations is given. Furthermore, open-string solutions are also discussed.

  11. An equivalence between momentum and charge in string theory

    International Nuclear Information System (INIS)

    Horne, J.H.; Horowitz, G.T.; Steif, A.R.

    1992-01-01

    It is shown that for a translationally invariant solution to string theory, spacetime duality interchanges the momentum in the symmetry direction and the axion charge per unit length. As one application, we show explicitly that charged black strings are equivalent to boosted (uncharged) black strings. The extremal black strings (which correspond to the field outside of a fundamental macroscopic string) are equivalent to plane-fronted waves describing strings moving at the speed of light

  12. The confining trailing string

    CERN Document Server

    Kiritsis, E; Nitti, F

    2014-01-01

    We extend the holographic trailing string picture of a heavy quark to the case of a bulk geometry dual to a confining gauge theory. We compute the classical trailing confining string solution for a static as well as a uniformly moving quark. The trailing string is infinitely extended and approaches a confining horizon, situated at a critical value of the radial coordinate, along one of the space-time directions, breaking boundary rotational invariance. We compute the equations for the fluctuations around the classical solutions, which are used to obtain boundary force correlators controlling the Langevin dynamics of the quark. The imaginary part of the correlators has a non-trivial low-frequency limit, which gives rise to a viscous friction coefficient induced by the confining vacuum. The vacuum correlators are used to define finite-temperature dressed Langevin correlators with an appropriate high-frequency behavior.

  13. String field representation of the Virasoro algebra

    Energy Technology Data Exchange (ETDEWEB)

    Mertes, Nicholas [Institute of Physics AS CR,Na Slovance 2, Prague 8 (Czech Republic); Department of Physics, University of Miami,Coral Gables, FL (United States); Schnabl, Martin [Institute of Physics AS CR,Na Slovance 2, Prague 8 (Czech Republic)

    2016-12-29

    We construct a representation of the zero central charge Virasoro algebra using string fields in Witten’s open bosonic string field theory. This construction is used to explore extensions of the KBc algebra and find novel algebraic solutions of open string field theory.

  14. Ubiquity of non-geometry in heterotic compactifications

    Energy Technology Data Exchange (ETDEWEB)

    García-Etxebarria, Iñaki [Max Planck Institute for Physics,Föhringer Ring 6, 80805 Munich (Germany); Lüst, Dieter [Max Planck Institute for Physics,Föhringer Ring 6, 80805 Munich (Germany); Arnold Sommerfeld Center for Theoretical Physics,Theresienstraße 37, 80333 Munich (Germany); Massai, Stefano [Enrico Fermi Institute, University of Chicago,5640 S Ellis Ave, Chicago, IL 60637 (United States); Arnold Sommerfeld Center for Theoretical Physics,Theresienstraße 37, 80333 Munich (Germany); Mayrhofer, Christoph [Arnold Sommerfeld Center for Theoretical Physics,Theresienstraße 37, 80333 Munich (Germany)

    2017-03-08

    We study the effect of quantum corrections on heterotic compactifications on elliptic fibrations away from the stable degeneration limit, elaborating on a recent observation by Malmendier and Morrison. We show that already for the simplest non-trivial elliptic fibration the effect is quite dramatic: the I{sub 1} degeneration with trivial gauge background dynamically splits into two T-fects with monodromy around each T-fect being (conjugate to) T-duality along one of the legs of the T{sup 2}. This implies that almost every elliptic heterotic compactification becomes a non-geometric T-fold away from the stable degeneration limit. We also point out a subtlety due to this non-geometric splitting at finite fiber size. It arises when determining, via heterotic/F-theory duality, the SCFTs associated to a small number of pointlike instantons probing heterotic ADE singularities. Along the way we resolve various puzzles in the literature.

  15. Multiquark strings

    International Nuclear Information System (INIS)

    Wang, F.; Chun, W.

    1985-01-01

    The use of basis states described as hadronic (or hadron-hadron) or hidden-colour (or colour-colour) for a system of quarks does not necessarily imply that connected exotic multiquark hadrons do exist. Antisymmetrization of quark wave functions tends to make these descriptions ill defined. It appears necessary to have stable collective structures called strings or bags to provide the physical connections required by quark confinement. The masses of multiquark hadrons can then be estimated by using semplified string, bag and NR potential models. The results turn out to be qualitatively similar in all these models. The stability problem for multiquark strings is briefly discussed

  16. Supersymmetry and String Theory: Beyond the Standard Model

    International Nuclear Information System (INIS)

    Rocek, Martin

    2007-01-01

    When I was asked to review Michael Dine's new book, 'Supersymmetry and String Theory', I was pleased to have a chance to read a book by such an established authority on how string theory might become testable. The book is most useful as a list of current topics of interest in modern theoretical physics. It gives a succinct summary of a huge variety of subjects, including the standard model, symmetry, Yang-Mills theory, quantization of gauge theories, the phenomenology of the standard model, the renormalization group, lattice gauge theory, effective field theories, anomalies, instantons, solitons, monopoles, dualities, technicolor, supersymmetry, the minimal supersymmetric standard model, dynamical supersymmetry breaking, extended supersymmetry, Seiberg-Witten theory, general relativity, cosmology, inflation, bosonic string theory, the superstring, the heterotic string, string compactifications, the quintic, string dualities, large extra dimensions, and, in the appendices, Goldstone's theorem, path integrals, and exact beta-functions in supersymmetric gauge theories. Its breadth is both its strength and its weakness: it is not (and could not possibly be) either a definitive reference for experts, where the details of thorny technical issues are carefully explored, or a textbook for graduate students, with detailed pedagogical expositions. As such, it complements rather than replaces the much narrower and more focussed String Theory I and II volumes by Polchinski, with their deep insights, as well the two older volumes by Green, Schwarz, and Witten, which develop string theory pedagogically. (book review)

  17. Cosmic strings

    International Nuclear Information System (INIS)

    Bennett, D.P.

    1988-07-01

    Cosmic strings are linear topological defects that are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation that are based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characteristic microwave background anistropy. It has recently been discovered by F. Bouchet and myself that details of cosmic string evolution are very different from the so-called ''standard model'' that has been assumed in most of the string induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain. 29 refs., 9 figs

  18. Lattice strings

    International Nuclear Information System (INIS)

    Thorn, C.B.

    1988-01-01

    The possibility of studying non-perturbative effects in string theory using a world sheet lattice is discussed. The light-cone lattice string model of Giles and Thorn is studied numerically to assess the accuracy of ''coarse lattice'' approximations. For free strings a 5 by 15 lattice seems sufficient to obtain better than 10% accuracy for the bosonic string tachyon mass squared. In addition a crude lattice model simulating string like interactions is studied to find out how easily a coarse lattice calculation can pick out effects such as bound states which would qualitatively alter the spectrum of the free theory. The role of the critical dimension in obtaining a finite continuum limit is discussed. Instead of the ''gaussian'' lattice model one could use one of the vertex models, whose continuum limit is the same as a gaussian model on a torus of any radius. Indeed, any critical 2 dimensional statistical system will have a stringy continuum limit in the absence of string interactions. 8 refs., 1 fig. , 9 tabs

  19. Pre-geometrical field theory of the open string

    International Nuclear Information System (INIS)

    Nojiri, M.M.; Nojiri, Shin'ichi

    1988-01-01

    We propose a gauge invariant, background independent string action, which contains open and closed string fields and no kinetic terms. The kinetic term is generated through the condensation of the string fields, which is the solution of the equations of motion. We solve the equations and show that the action is classically equivalent to the open string action proposed by Hata et al. (orig.)

  20. D-strings in unconventional type I vacuum configurations

    International Nuclear Information System (INIS)

    Bianchi, M.; Gava, E.; Morales, F.; Narain, K.S.

    1998-11-01

    We determine the spectrum of D-string bound states in various classes of generalized type I vacuum configurations with sixteen and eight supercharges. The precise matching of the BPS spectra confirms the duality between unconventional type IIB orientfolds with quantized NS-NS antisymmetric tensor and heterotic CHL models in D=8. A similar analysis puts the duality between type II (4,0) models and type I strings without open strings on a firmer ground. The analysis can be extended to type II (2,0) asymmetric orbifolds and their type I duals that correspond to unconventional K3 compactifications. Finally we discuss BPS-saturated threshold corrections to the corresponding low-energy effective lagrangians. In particular we show how the exact moduli dependence of some F 4 terms in the eight-dimensional type II (4,0) orbifold is reproduced by the infinite sum of D-instanton contributions in the dual type I theory. (author)

  1. Top-quark mass coupling and classification of weakly coupled heterotic superstring vacua

    International Nuclear Information System (INIS)

    Rizos, J.

    2014-01-01

    The quest for the Standard Model among the huge number of string vacua is usually based on a set of phenomenological criteria related to the massless spectrum of string models. In this work we study criteria associated with interactions in the effective low energy theory and in particular with the presence of the coupling that provides mass to the top quark. Working in the context of the free-fermionic formulation of the heterotic superstring, we demonstrate that, in a big class of phenomenologically promising Z 2 x Z 2 compactifications, these criteria can be expressed entirely in terms of the generalised GSO projection coefficients entering the definition of the models. They are shown to be very efficient in identifying phenomenologically viable vacua, especially in the framework of computer-based search, as they are met by approximately one every 10 4 models. We apply our results in the investigation of a class of supersymmetric Pati-Salam vacua, comprising 10 16 configurations, and we show that when combined with other phenomenological requirements they lead to a relatively small set of about 10 7 Standard Model compatible models that can be fully classified. (orig.)

  2. Top-quark mass coupling and classification of weakly coupled heterotic superstring vacua

    Science.gov (United States)

    Rizos, J.

    2014-06-01

    The quest for the Standard Model among the huge number of string vacua is usually based on a set of phenomenological criteria related to the massless spectrum of string models. In this work we study criteria associated with interactions in the effective low energy theory and in particular with the presence of the coupling that provides mass to the top quark. Working in the context of the free-fermionic formulation of the heterotic superstring, we demonstrate that, in a big class of phenomenologically promising compactifications, these criteria can be expressed entirely in terms of the generalised GSO projection coefficients entering the definition of the models. They are shown to be very efficient in identifying phenomenologically viable vacua, especially in the framework of computer-based search, as they are met by approximately one every models. We apply our results in the investigation of a class of supersymmetric Pati-Salam vacua, comprising configurations, and we show that when combined with other phenomenological requirements they lead to a relatively small set of about Standard Model compatible models that can be fully classified.

  3. Open spinning strings

    International Nuclear Information System (INIS)

    Stefanski, B. Jr.

    2004-01-01

    We find classical open string solutions in the AdS 5 x S 5 /Z 2 orientifold with angular momenta along the five-sphere. The energy of these solutions has an expansion in integral powers of λ with sigma-model corrections suppressed by inverse powers of J - the total angular momentum. This gives a prediction for the exact anomalous dimensions of operators in the large N limit of an N = 2 Sp, Super-Yang-Mills theory with matter. We also find a simple map between open and closed string solutions. This gives a prediction for an all-loop planar relationship between the anomalous dimensions of single-trace and two-quark operators in the dual gauge theory. (author)

  4. Singleton strings

    International Nuclear Information System (INIS)

    Engquist, J.; Sundell, P.; Tamassia, L.

    2007-01-01

    The group theoretical structure underlying physics in anti de Sitter (AdS) spacetime is intrinsically different with respect to the flat case, due to the presence of special ultra-short representations, named singletons, that do not admit a flat space limit. The purpose of this collaboration is to exploit this feature in the study of string and brane dynamics in AdS spacetime, in particular while trying to establish a connection between String Theory in AdS backgrounds (in the tensionless limit) and Higher-Spin Gauge Theory. (orig.)

  5. 1/4 BPS States and Non-Perturbative Couplings in N=4 String Theories

    CERN Document Server

    Lerche, W.

    1999-01-01

    We compute certain 2K+4-point one-loop couplings in the type IIA string compactified on K3 x T^2, which are related a topological index on this manifold. Their special feature is that they are sensitive to only short and intermediate BPS multiplets. The couplings derive from underlying prepotentials of the form G(T,U)=d^{2K}V ln[chi10(T,U,V)], where chi10(T,U,V) is the helicity partition function of 1/4 BPS states. In the dual heterotic string on T^6, the amplitudes describe non-perturbative gravitational corrections due to bound states of fivebrane instantons with heterotic world-sheet instantons. We argue, as a consequence, that our results give information about instanton configurations in six dimensional Sp(2k) gauge theories on T^6.

  6. String phenomenology

    CERN Document Server

    Ibáñez, Luis E

    2015-01-01

    This chapter reviews a number of topics in the field of string phenomenology, focusing on orientifold/F-theory models yielding semirealistic low-energy physics. The emphasis is on the extraction of the low-energy effective action and possible tests of specific models at the LHC.

  7. String GUTs

    International Nuclear Information System (INIS)

    Aldazabal, G.; Ibanez, L.E.; Uranga, A.M.

    1995-01-01

    Standard SUSY-GUTs such as those based on SU(5) or SO(10) lead to predictions for the values of α s and sin 2 θ W in amazing agreement with experiment. In this article we investigate how these models may be obtained from string theory, thus bringing them into the only known consistent framework for quantum gravity. String models with matter in standard GUT representations require the realization of affine Lie algebras at higher levels. We start by describing some methods to build level k=2 symmetric orbifold string models with gauge groups SU(5) or SO(10). We present several examples and identify generic features of the type of models constructed. Chiral fields appropriate to break the symmetry down to the standard model generically appear in the massless spectrum. However, unlike in standard SUSY-GUTs, they often behave as string moduli, i.e., they do not have self-couplings. We also discuss briefly the doublet-triplet Higgs splitting. We find that, in some models, built-in sliding-singlet type of couplings exist. (orig.)

  8. Kinetic Mixing of U(1)s in Heterotic Orbifolds

    CERN Document Server

    Goodsell, Mark; Ringwald, Andreas

    2012-01-01

    We study kinetic mixing between massless U(1) gauge symmetries in the bosonic formulation of heterotic orbifold compactifications. For non-prime Z_N factorisable orbifolds, we find a simple expression of the mixing in terms of the properties of the N=2 subsectors, which helps understand under what conditions mixing can occur. With this tool, we analyse Z_6-II heterotic orbifolds and find non-vanishing mixing even without including Wilson lines. We show that some semi-realistic models of the Mini-Landscape admit supersymmetric vacua with mixing between the hypercharge and an additional U(1), which can be broken at low energies. We finally discuss some phenomenologically appealing possibilities that hidden photons in heterotic orbifolds allow.

  9. Kinetic mixing of U(1)s in heterotic orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Goodsell, Mark [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Ramos-Sanchez, Saul [UNAM, Mexico (Mexico). Dept. of Theoretical Physics; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-10-15

    We study kinetic mixing between massless U(1) gauge symmetries in the bosonic formulation of heterotic orbifold compactifications. For non-prime Z{sub N} factorisable orbifolds, we find a simple expression of the mixing in terms of the properties of the N=2 subsectors, which helps understand under what conditions mixing can occur. With this tool, we analyse Z{sub 6}-II heterotic orbifolds and find non-vanishing mixing even without including Wilson lines. We show that some semi-realistic models of the Mini-Landscape admit supersymmetric vacua with mixing between the hypercharge and an additional U(1), which can be broken at low energies. We finally discuss some phenomenologically appealing possibilities that hidden photons in heterotic orbifolds allow. (orig.)

  10. A novel class of string models with Scherk-Schwarz supersymmetry breaking

    CERN Document Server

    Scrucca, Claudio A; Scrucca, Claudio A.; Serone, Marco

    2001-01-01

    A new type of four-dimensional string vacua with Scherk--Schwarz supersymmetry breaking is considered. The construction involves Z_N x Z_M' freely acting orbifolds, defined in terms of rotations and translations in the internal space. Tachyons are either absent or limited to a given region of the tree-level moduli space. Particular attention is devoted to an interesting Z_3 x Z_3' heterotic example.

  11. Black strings and classical hair

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Yang, H.

    1997-01-01

    We examine the geometry near the event horizon of a family of black string solutions with traveling waves. It has previously been shown that the metric is continuous there. Contrary to expectations, we find that the geometry is not smooth, and the horizon becomes singular whenever a wave is present. Both five-dimensional and six-dimensional black strings are considered with similar results. copyright 1997 The American Physical Society

  12. Supersymmetry Constraints and String Theory on K3

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ying-Hsuan; Shao, Shu-Heng [Jefferson Physical Laboratory, Harvard University,Cambridge, MA 02138 (United States); Wang, Yifan [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Yin, Xi [Jefferson Physical Laboratory, Harvard University,Cambridge, MA 02138 (United States)

    2015-12-22

    We study supervertices in six dimensional (2,0) supergravity theories, and derive supersymmetry non-renormalization conditions on the 4- and 6-derivative four-point couplings of tensor multiplets. As an application, we obtain exact non-perturbative results of such effective couplings in type IIB string theory compactified on K3 surface, extending previous work on type II/heterotic duality. The weak coupling limit thereof, in particular, gives certain integrated four-point functions of half-BPS operators in the nonlinear sigma model on K3 surface, that depend nontrivially on the moduli, and capture worldsheet instanton contributions.

  13. Self-dual nonsupersymmetric Type II String Compactifications

    International Nuclear Information System (INIS)

    Kachru, Shamit; Silverstein, Eva

    1998-01-01

    It has recently been proposed that certain nonsupersymmetric type II orbifolds have vanishing perturbative contributions to the cosmological constant. We show that techniques of Sen and Vafa allow one to construct dual type II descriptions of these models (some of which have no weakly coupled heterotic dual). The dual type II models are given by the same orbifolds with the string coupling S and a T 2 volume T exchanged. This allows us to argue that in various strongly coupled limits of the original type II models, there are weakly coupled duals which exhibit the same perturbative cancellations as the original models

  14. Moving five-branes and membrane instantons in low energy heterotic M theory

    International Nuclear Information System (INIS)

    Carlos, Beatriz de; Roberts, Jonathan; Schmoehe, Yaiza

    2005-01-01

    We study cosmological solutions in the context of four-dimensional low energy heterotic M theory with moving bulk branes. First we present nontrivial, analytic axion solutions generated by new symmetries of the full potential-free action, and we discuss their relation to 'triple axion' solutions found in Pre-Big-Bang cosmologies. Next we consider the presence of a nonperturbative superpotential with and without a background perfect fluid. In the absence of a fluid the dilaton and the T-modulus go to the potential-free solutions at late time, while the moving brane tries to avoid colliding with the boundary and stabilize within the bulk. When the fluid is included the dynamics of the fields change, and we study their behavior both numerically and analytically. In particular we examine the possibility of this setup being a realization of the quintessential scenario and the impact of the fluid on the cosmological stabilization of the moduli

  15. Open string topological amplitudes and gaugino masses

    International Nuclear Information System (INIS)

    Antoniadis, I.; Narain, K.S.; Taylor, T.R.

    2005-09-01

    We discuss the moduli-dependent couplings of the higher derivative F-terms (TrW 2 ) h-1 , where W is the gauge N =1 chiral superfield. They are determined by the genus zero topological partition function F (0,h) , on a world-sheet with h boundaries. By string duality, these terms are also related to heterotic topological amplitudes studied in the past, with the topological twist applied only in the left-moving supersymmetric sector of the internal N =(2,0) superconformal field theory. The holomorphic anomaly of these couplings relates them to terms of the form Π n (TrW 2 ) h-2 , where Π's represent chiral projections of non-holomorphic functions of chiral superfields. An important property of these couplings is that they violate R-symmetry for h ≥ 3. As a result, once supersymmetry is broken by D-term expectation values, (TrW 2 ) 2 generates gaugino masses that can be hierarchically smaller than the scalar masses, behaving as m 1/2 ∼ m 0 4 in string units. Similarly, ΠTrW 2 generates Dirac masses for non-chiral brane fermions, of the same order of magnitude. This mechanism can be used for instance to obtain fermion masses at the TeV scale for scalar masses as high as m 0 ∼ O (10 13 ) GeV. We present explicit examples in toroidal string compactifications with intersecting D-branes. (author)

  16. Scaling laws for nonintercommuting cosmic string networks

    International Nuclear Information System (INIS)

    Martins, C.J.A.P.

    2004-01-01

    We study the evolution of noninteracting and entangled cosmic string networks in the context of the velocity-dependent one-scale model. Such networks may be formed in several contexts, including brane inflation. We show that the frozen network solution L∝a, although generic, is only a transient one, and that the asymptotic solution is still L∝t as in the case of ordinary (intercommuting) strings, although in the present context the universe will usually be string dominated. Thus the behavior of two strings when they cross does not seem to affect their scaling laws, but only their densities relative to the background

  17. Fermions on the electroweak string

    CERN Document Server

    Moreno, J M; Quirós, Mariano; Moreno, J M; Oaknin, D H; Quiros, M

    1995-01-01

    We construct a simple class of exact solutions of the electroweak theory including the naked Z--string and fermion fields. It consists in the Z--string configuration (\\phi,Z_\\theta), the {\\it time} and z components of the neutral gauge bosons (Z_{0,3},A_{0,3}) and a fermion condensate (lepton or quark) zero mode. The Z--string is not altered (no feed back from the rest of fields on the Z--string) while fermion condensates are zero modes of the Dirac equation in the presence of the Z--string background (no feed back from the {\\it time} and z components of the neutral gauge bosons on the fermion fields). For the case of the n--vortex Z--string the number of zero modes found for charged leptons and quarks is (according to previous results by Jackiw and Rossi) equal to |n|, while for (massless) neutrinos is |n|-1. The presence of fermion fields in its core make the obtained configuration a superconducting string, but their presence (as well as that of Z_{0,3},A_{0,3}) does not enhance the stability of the Z--stri...

  18. Boundary terms in the Nambu-Goto string action

    Science.gov (United States)

    Hadasz, Leszek; Wȩgrzyn, Paweł

    1995-03-01

    We investigate classical strings defined by the Nambu-Goto action with the boundary term added. We demonstrate that the latter term has a significant bearing on the string dynamics. It is confirmed that new action terms that depend on higher order derivatives of string coordinates cannot be considered as continuous perturbations from the starting string functional. In the case when the boundary term reduces to the Gauss-Bonnet term, a stability analysis is performed on the rotating rigid string solution. We determine the most generic solution that the fluctuations grow to. Longitudinal string excitations are found. The Regge trajectories are nonlinear.

  19. Boundary terms in the Nambu-Goto string action

    International Nuclear Information System (INIS)

    Hadasz, L.; Wegrzyn, P.

    1995-01-01

    We investigate classical strings defined by the Nambu-Goto action with the boundary term added. We demonstrate that the latter term has a significant bearing on the string dynamics. It is confirmed that new action terms that depend on higher order derivatives of string coordinates cannot be considered as continuous perturbations from the starting string functional. In the case when the boundary term reduces to the Gauss-Bonnet term, a stability analysis is performed on the rotating rigid string solution. We determine the most generic solution that the fluctuations grow to. Longitudinal string excitations are found. The Regge trajectories are nonlinear

  20. Counting states of black strings with traveling waves

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Marolf, D.

    1997-01-01

    We consider a family of solutions to string theory which depend on arbitrary functions and contain regular event horizons. They describe six-dimensional extremal black strings with traveling waves and have an inhomogeneous distribution of momentum along the string. The structure of these solutions near the horizon is studied and the horizon area computed. We also count the number of BPS string states at weak coupling whose macroscopic momentum distribution agrees with that of the black string. It is shown that the number of such states is given by the Bekenstein-Hawking entropy of the black string with traveling waves. copyright 1997 The American Physical Society

  1. String flipped SO(10) model from [ital Z][sub 4] orbifold

    Energy Technology Data Exchange (ETDEWEB)

    Sato, H. (Department of Physics, Hyogo University of Education, Yashiro-cho, Hyogo 673-14 (Japan)); Shimojo, M. (Department of Electronics and Information Engineering, Fukui National College of Technology, Sabae, Fukui 916 (Japan))

    1993-12-15

    We search all possible string grand-unified-theory models obtained from heterotic superstrings compactified on a [ital Z][sub 4] orbifold with one Wilson line. It is shown that there is an essentially unique anomaly-free flipped SO(10) model with three generations plus one mirror conjugate generation of matter fields. We derive effective Yukawa interactions and examine the structure of mass matrices as well as a possible scenario of string coupling unification. The four-generation [ital Z][sub 4] orbifold model is a phenomenologically viable model beyond the minimal supersymmetric standard one.

  2. Five-brane superpotentials and heterotic/F-theory duality

    International Nuclear Information System (INIS)

    Grimm, Thomas W.; Ha, Tae-Won; Klemm, Albrecht; Klevers, Denis

    2010-01-01

    Under heterotic/F-theory duality it was argued that a wide class of heterotic five-branes is mapped into the geometry of an F-theory compactification manifold. In four-dimensional compactifications this identifies a five-brane wrapped on a curve in the base of an elliptically fibered Calabi-Yau threefold with a specific F-theory Calabi-Yau fourfold containing the blow-up of the five-brane curve. We argue that this duality can be reformulated by first constructing a non-Calabi-Yau heterotic threefold by blowing up the curve of the five-brane into a divisor with five-brane flux. Employing heterotic/F-theory duality this leads us to the construction of a Calabi-Yau fourfold and four-form flux. Moreover, we obtain an explicit map between the five-brane superpotential and an F-theory flux superpotential. The map of the open-closed deformation problem of a five-brane in a compact Calabi-Yau threefold into a deformation problem of complex structures on a dual Calabi-Yau fourfold with four-form flux provides a powerful tool to explicitly compute the five-brane superpotential.

  3. Heterotic superstring and curved, scale-invariant superspace

    International Nuclear Information System (INIS)

    Kuusk, P.K.

    1988-01-01

    It is shown that the modified heterotic superstring [R. E. Kallosh, JETP Lett. 43, 456 (1986); Phys. Lett. 176B, 50 (1986)] demands a scale-invariant superspace for its existence. Explicit expressions are given for the connection, the torsion, and the curvature of an extended scale-invariant superspace with 506 bosonic and 16 fermionic coordinates

  4. Heterotic responses of tetraploid and triploid plantain hybrids in ...

    African Journals Online (AJOL)

    Heterotic responses of tetraploid and triploid plantain hybrids in southeast Nigeria under alley-cropping. V Wilson, A Tenkouano. Abstract. (African Crop Science Journal: 1999 7(2): 117-124). AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's ...

  5. Heterotic Pomeron: high energy hadronic collisions in QCD

    International Nuclear Information System (INIS)

    Chung-I Tan

    1993-01-01

    A unified treatment of high energy collisions in QCD is presented. Using a probabilistic approach, both perturbative (hard) and non-perturbative (soft) components are incorporated in a consistent fashion, leading to a ''Heterotic Pomeron''. As a Regge trajectory, it is non linear, approaching 1 in the limit t → -∞. 2 tabs., 9 refs

  6. Dynamical evolution of cosmic strings

    International Nuclear Information System (INIS)

    Bouchet, F.R.

    1988-01-01

    The author have studied by means of numerical simulations the dynamical evolution of a network of cosmic strings, both in the radiation and matter era. Our basic conclusion is that a scaling solution exists, i.e., the string energy density evolves as t -2 . This means that the process by which long strings dump their energy into closed loops (which can gravitationally radiate away) is efficient enough to prevent the string domination over other forms of energy. This conclusion does not depend on the initial string energy density, nor on the various numerical parameters. On the other hand, the generated spectrum of loop sizes does depend on the value of our numerical lower cutoff (i.e., the minimum length of loop we allow to be chopped off the network). Furthermore, the network evolution is very different from what was assumed before), namely the creation of a few horizon sized loops per horizon volume and per hubble time, which subsequently fragment into about 10 smaller daughter loops. Rather, many tiny loops are directly cut from the network of infinite strings, and it appears that the only fundamental scale (the horizon) has been lost. This is probably because a fundamental ingredient had been overlooked, namely the kinks. These kinks are created in pairs at each intercommutation, and very rapidly, the long strings appear to be very kinky. Thus the number of long strings per horizon is still of the order of a few, but their total length is fairly large. Furthermore, a large number of kinks favors the formation of small loops, and their sizes might well be governed by the kink density along the long strings. Finally, we computed the two-point correlation function of the loops and found significant differences from the work of Turok

  7. On the consistency and high-energy behavior of string theory

    International Nuclear Information System (INIS)

    Mende, P.F.

    1988-01-01

    In Part I, it is shown that the heterotic string is free of gauge and gravitational anomalies by showing that (a) unless the gauge group is E S x E S or Spin(32)/Z 2 or a subgroup, the internal sector partition function vanishes so there is no consistent theory; and (b) for E 8 x E 8 and Spin(32)/Z 2 compactifications, the longitudinal modes of the massless gauge particles decouple, as required by gauge invariance. We discuss the geometric interpretation for string theory when the action is invariant under a modular subgroup. In Part II, the high-energy behavior of string scattering amplitudes is studied to all orders in perturbation theory, with the aim of exploring the short-distance structure of string theory. It is shown that the sum over all Riemann surfaces is dominated by a saddle point. Consequently, the high-energy limit is universal and simple to calculate. In this limit the amplitudes fall off much faster than allowed by field theory. The dominant saddle points are identified as coming from world sheets which are Z G+1 symmetric algebraic curves, and their contribution to the scattering amplitude is evaluated for the bosonic to all orders and for the heterotic string to two-loop order. An interesting spacetime picture of the high-energy limit emerges. The issue of summing the perturbation expansion is addressed

  8. The orbifolder: A tool to study the low-energy effective theory of heterotic orbifolds

    Science.gov (United States)

    Nilles, H. P.; Ramos-Sánchez, S.; Vaudrevange, P. K. S.; Wingerter, A.

    2012-06-01

    The orbifolder is a program developed in C++ that computes and analyzes the low-energy effective theory of heterotic orbifold compactifications. The program includes routines to compute the massless spectrum, to identify the allowed couplings in the superpotential, to automatically generate large sets of orbifold models, to identify phenomenologically interesting models (e.g. MSSM-like models) and to analyze their vacuum configurations. Program summaryProgram title: orbifolder Catalogue identifier: AELR_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELR_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 145 572 No. of bytes in distributed program, including test data, etc.: 930 517 Distribution format: tar.gz Programming language:C++ Computer: Personal computer Operating system: Tested on Linux (Fedora 15, Ubuntu 11, SuSE 11) Word size: 32 bits or 64 bits Classification: 11.1 External routines: Boost (http://www.boost.org/), GSL (http://www.gnu.org/software/gsl/) Nature of problem: Calculating the low-energy spectrum of heterotic orbifold compactifications. Solution method: Quadratic equations on a lattice; representation theory; polynomial algebra. Running time: Less than a second per model.

  9. New Supersymmetric String Compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, Shamit

    2002-11-25

    We describe a new class of supersymmetric string compactifications to 4d Minkowski space. These solutions involve type II strings propagating on (orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR fluxes. The simplest examples have descriptions as cosets, generalizing the three-dimensional nilmanifold. They can also be thought of as twisted tori. We derive a formula for the (super)potential governing the light fields, which is generated by the fluxes and certain ''twists'' in the geometry. Detailed consideration of an example also gives strong evidence that in some cases, these exotic geometries are related by smooth transitions to standard Calabi-Yau or G2 compactifications of M-theory.

  10. Cosmic strings and black holes

    International Nuclear Information System (INIS)

    Aryal, M.; Ford, L.H.; Vilenkin, A.

    1986-01-01

    The metric for a Schwarzschild black hole with a cosmic string passing through it is discussed. The thermodynamics of such an object is considered, and it is shown that S = (1/4)A, where S is the entropy and A is the horizon area. It is noted that the Schwarzschild mass parameter M, which is the gravitational mass of the system, is no longer identical to its energy. A solution representing a pair of black holes held apart by strings is discussed. It is nearly identical to a static, axially symmetric solution given long ago by Bach and Weyl. It is shown how these solutions, which were formerly a mathematical curiosity, may be given a more physical interpretation in terms of cosmic strings

  11. String Gas Cosmology

    OpenAIRE

    Brandenberger, Robert H.

    2008-01-01

    String gas cosmology is a string theory-based approach to early universe cosmology which is based on making use of robust features of string theory such as the existence of new states and new symmetries. A first goal of string gas cosmology is to understand how string theory can effect the earliest moments of cosmology before the effective field theory approach which underlies standard and inflationary cosmology becomes valid. String gas cosmology may also provide an alternative to the curren...

  12. Closed string field theory

    International Nuclear Information System (INIS)

    Strominger, A.

    1987-01-01

    A gauge invariant cubic action describing bosonic closed string field theory is constructed. The gauge symmetries include local spacetime diffeomorphisms. The conventional closed string spectrum and trilinear couplings are reproduced after spontaneous symmetry breaking. The action S is constructed from the usual ''open string'' field of ghost number minus one half. It is given by the associator of the string field product which is non-vanishing because of associativity anomalies. S does not describe open string propagation because open string states associate and can thereby be shifted away. A field theory of closed and open strings can be obtained by adding to S the cubic open string action. (orig.)

  13. Reconciling grand unification with strings by anisotropic compactifications

    International Nuclear Information System (INIS)

    Dundee, Ben; Raby, Stuart; Wingerter, Akin

    2008-01-01

    We analyze gauge coupling unification in the context of heterotic strings on anisotropic orbifolds. This construction is very much analogous to effective five-dimensional orbifold grand unified theory field theories. Our analysis assumes three fundamental scales: the string scale M S , a compactification scale M C , and a mass scale for some of the vectorlike exotics M EX ; the other exotics are assumed to get mass at M S . In the particular models analyzed, we show that gauge coupling unification is not possible with M EX =M C , and in fact we require M EX C ∼3x10 16 GeV. We find that about 10% of the parameter space has a proton lifetime (from dimension six gauge exchange) 10 33 yr 0 e + ) 36 yr. The other 80% of the parameter space gives proton lifetimes below Super-Kamiokande bounds. The next generation of proton decay experiments should be sensitive to the remaining parameter space.

  14. Holomorphic couplings in non-perturbative string compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Klevers, Denis Marco

    2011-06-15

    In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z{sub 3}, that is canonically constructed from the original five-brane and Calabi-Yau threefold Z{sub 3} via a blow-up. We exploit the use of the blow-up threefold Z{sub 3} as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z{sub 3} as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z{sub 3}, that is generated dynamically by the five-brane backreaction. (orig.)

  15. Holomorphic couplings in non-perturbative string compactifications

    International Nuclear Information System (INIS)

    Klevers, Denis Marco

    2011-06-01

    In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z 3 , that is canonically constructed from the original five-brane and Calabi-Yau threefold Z 3 via a blow-up. We exploit the use of the blow-up threefold Z 3 as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z 3 as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z 3 , that is generated dynamically by the five-brane backreaction. (orig.)

  16. Rotating and orbiting strings in Dp-brane background

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Sagar; Panigrahi, Kamal L. [Department of Physics, Indian Institute of Technology Kharagpur,721302, Kharagpur (India)

    2015-03-04

    We probe the open fundamental strings in Dp-brane (p=1, 3, 5) backgrounds and find new classes of rotating and orbiting string solutions. We show that for various worldsheet embedding ansatz we get solutions of the string equations of motion that correspond to the well known giant magnon and single spikes, in addition to few new solutions corresponding to the orbiting strings. We make a systematic study of both rigidly rotating and orbiting strings in D1, D3 and D5-brane backgrounds.

  17. Multiple fibrations in Calabi-Yau geometry and string dualities

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Lara B.; Gao, Xin; Gray, James; Lee, Seung-Joo [Physics Department, Virginia Tech,Robeson Hall, Blacksburg, VA 24061 (United States)

    2016-10-19

    In this work we explore the physics associated to Calabi-Yau (CY) n-folds that can be described as a fibration in more than one way. Beginning with F-theory vacua in various dimensions, we consider limits/dualities with M-theory, type IIA, and heterotic string theories. Our results include many M-/F-theory correspondences in which distinct F-theory vacua — associated to different elliptic fibrations of the same CY n-fold — give rise to the same M-theory limit in one dimension lower. Examples include 5-dimensional correspondences between 6-dimensional theories with Abelian, non-Abelian and superconformal structure, as well as examples of higher rank Mordell-Weil geometries. In addition, in the context of heterotic/F-theory duality, we investigate the role played by multiple K3- and elliptic fibrations in known and novel string dualities in 8-, 6- and 4-dimensional theories. Here we systematically summarize nested fibration structures and comment on the roles they play in T-duality, mirror symmetry, and 4-dimensional compactifications of F-theory with G-flux. This investigation of duality structures is made possible by geometric tools developed in a companion paper http://arxiv.org/abs/1608.07554.

  18. BPS limit of multi- D- and DF-strings in boundary string field theory

    International Nuclear Information System (INIS)

    Go, Gyungchoon; Ishida, Akira; Kim, Yoonbai

    2007-01-01

    A BPS limit is systematically derived for straight multi- D- and DF-strings from the D3D-bar3 system in the context of boundary superstring field theory. The BPS limit is obtained in the limit of thin D(F)-strings, where the Bogomolny equation supports singular static multi-D(F)-string solutions. For the BPS multi-string configurations with arbitrary separations, BPS sum rule is fulfilled under a Gaussian type tachyon potential and reproduces exactly the descent relation. For the DF-strings ((p,q)-strings), the distribution of fundamental string charge density coincides with its energy density and the Hamiltonian density takes the BPS formula of square-root form

  19. String theory on the edge

    International Nuclear Information System (INIS)

    Thorlacius, L.

    1989-01-01

    Open string vacuum configurations are described in terms of a one-dimensional field theory on the worldsheet boundary. The one-dimensional path integral has direct physical interpretation as a source term for closed string fields. This means that the vacuum divergences (Mobius infinities) of the path integral must be renormalized correctly. The author shows that reparametrization invariance Ward identities, apart from specifying the equations of motion of spacetime background gauge fields, also serve to fix the renormalization scheme of the vacuum divergences. He argues that vacuum configurations of open strings correspond to Caldeira-Leggett models of dissipative quantum mechanics (DQM) evaluated at a delocalization critical point. This connection reveals that critical DQM will manifest reparametrization invariance (inherited from the conformal invariance of string theory) rather than just scale invariance. This connection should open up new ways of constructing analytic and approximate solutions of open string theory (in particular, topological solitons such as monopoles and instantons). Type I superstring theory gives rise to a supersymmetric boundary field theory. Bose-Fermi cancellation eliminates vacuum divergences but the one-loop beta function remains the same as in the bosonic theory. Reparametrization invariance Ward identities dictate a boundary state normalization which yields consistent string-loop corrections to spacetime equations of motion, in both the periodic and anti-periodic fermion sectors

  20. Black string in dRGT massive gravity

    Energy Technology Data Exchange (ETDEWEB)

    Tannukij, Lunchakorn [Mahidol University, Department of Physics, Faculty of Science, Bangkok (Thailand); Hanyang University, Department of Physics, Seoul (Korea, Republic of); Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Wongjun, Pitayuth [Naresuan University, The Institute for Fundamental Study, Phitsanulok (Thailand); Ministry of Education, Thailand Center of Excellence in Physics, Bangkok (Thailand); Ghosh, Suchant G. [Jamia Millia Islamia, Centre of Theoretical Physics, New Delhi (India); University of Kwazulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Durban (South Africa)

    2017-12-15

    We present a cylindrically symmetric solution, both charged and uncharged, which is known as a black string solution to the nonlinear ghost-free massive gravity found by de Rham, Gabadadze, and Tolley (dRGT). This ''dRGT black string'' can be thought of as a generalization of the black string solution found by Lemos. Moreover, the dRGT black string solution includes other classes of black string solution such as the monopole-black string ones since the graviton mass contributes to the global monopole term as well as the cosmological-constant term. To investigate the solution, we compute mass, temperature, and entropy of the dRGT black string. We found that the existence of the graviton mass drastically affects the thermodynamics of the black string. Furthermore, the Hawking-Page phase transition is found to be possible for the dRGT black string as well as the charged dRGT black string. The dRGT black string solution is thermodynamically stable for r > r{sub c} with negative thermodynamical potential and positive heat capacity while it is unstable for r < r{sub c} where the potential is positive. (orig.)

  1. Gravity and strings

    CERN Document Server

    Ortín, Tomás

    2015-01-01

    Self-contained and comprehensive, this definitive new edition of Gravity and Strings is a unique resource for graduate students and researchers in theoretical physics. From basic differential geometry through to the construction and study of black-hole and black-brane solutions in quantum gravity - via all the intermediate stages - this book provides a complete overview of the intersection of gravity, supergravity, and superstrings. Now fully revised, this second edition covers an extensive array of topics, including new material on non-linear electric-magnetic duality, the electric-tensor formalism, matter-coupled supergravity, supersymmetric solutions, the geometries of scalar manifolds appearing in 4- and 5-dimensional supergravities, and much more. Covering reviews of important solutions and numerous solution-generating techniques, and accompanied by an exhaustive index and bibliography, this is an exceptional reference work.

  2. Cosmic global strings

    International Nuclear Information System (INIS)

    Sikivie, P.

    1991-01-01

    The topics are: global strings; the gravitational field of a straight global string; how do global strings behave?; the axion cosmological energy density; computer simulations of the motion and decay of global strings; electromagnetic radiation from the conversion of Nambu-Goldstone bosons in astrophysical magnetic fields. (orig.)

  3. Evidence for string substructure

    International Nuclear Information System (INIS)

    Bergman, O.

    1996-06-01

    The author argues that the behavior of string theory at high temperature and high longitudinal boosts, combined with the emergence of p-branes as necessary ingredients in various string dualities, point to a possible reformulation of strings, as well as p-branes, as composites of bits. He reviews the string-bit models, and suggests generalizations to incorporate p-branes

  4. String consistency for unified model building

    International Nuclear Information System (INIS)

    Chaudhuri, S.; Chung, S.W.; Hockney, G.; Lykken, J.

    1995-01-01

    We explore the use of real fermionization as a test case for understanding how specific features of phenomenological interest in the low-energy effective superpotential are realized in exact solutions to heterotic superstring theory. We present pedagogic examples of models which realize SO(10) as a level two current algebra on the world-sheet, and discuss in general how higher level current algebras can be realized in the tensor product of simple constituent conformal field theories. We describe formal developments necessary to compute couplings in models built using real fermionization. This allows us to isolate cases of spin structures where the standard prescription for real fermionization may break down. (orig.)

  5. Natural inflation and moduli stabilization in heterotic orbifolds

    International Nuclear Information System (INIS)

    Ruehle, Fabian; Wieck, Clemens

    2015-03-01

    We study moduli stabilization in combination with inflation in heterotic orbifold compactifications in the light of a large Hubble scale and the favored tensor-to-scalar ratio r∼0.05. To account for a trans-Planckian field range we implement aligned natural inflation. Although there is only one universal axion in heterotic constructions, further axions from the geometric moduli can be used for alignment and inflation. We argue that such an alignment is rather generic on orbifolds, since all non-perturbative terms are determined by modular weights of the involved fields and the Dedekind η function. We present two setups inspired by the mini-landscape models of the Z 6-II orbifold which realize aligned inflation and stabilization of the relevant moduli. One has a supersymmetric vacuum after inflation, while the other includes a gaugino condensate which breaks supersymmetry at a high scale.

  6. Gauge unification in highly anisotropic string compactifications

    International Nuclear Information System (INIS)

    Hebecker, A.; Trapletti, M.

    2005-01-01

    It is well known that heterotic string compactifications have, in spite of their conceptual simplicity and aesthetic appeal, a serious problem with precision gauge coupling unification in the perturbative regime of string theory. Using both a duality-based and a field-theoretic definition of the boundary of the perturbative regime, we reevaluate the situation in a quantitative manner. We conclude that the simplest and most promising situations are those where some of the compactification radii are exceptionally large, corresponding to highly anisotropic orbifold models. Thus, one is led to consider constructions which are known to the effective field-theorist as higher-dimensional or orbifold grand unified theories (orbifold GUTs). In particular, if the discrete symmetry used to break the GUT group acts freely, a non-local breaking in the larger compact dimensions can be realized, leading to a precise gauge coupling unification as expected on the basis of the MSSM particle spectrum. Furthermore, a somewhat more model dependent but nevertheless very promising scenario arises if the GUT breaking is restricted to certain singular points within the manifold spanned by the larger compactification radii

  7. String driven inflation

    International Nuclear Information System (INIS)

    Turok, N.

    1987-11-01

    It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation. 17 refs., 1 fig

  8. Hot String Soup

    OpenAIRE

    Lowe, D. A.; Thorlacius, L.

    1994-01-01

    Above the Hagedorn energy density closed fundamental strings form a long string phase. The dynamics of weakly interacting long strings is described by a simple Boltzmann equation which can be solved explicitly for equilibrium distributions. The average total number of long strings grows logarithmically with total energy in the microcanonical ensemble. This is consistent with calculations of the free single string density of states provided the thermodynamic limit is carefully defined. If the ...

  9. String-driven inflation

    International Nuclear Information System (INIS)

    Turok, N.

    1988-01-01

    It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation

  10. Non-critical Poincare invariant bosonic string backgrounds and closed string tachyons

    International Nuclear Information System (INIS)

    Alvarez, Enrique; Gomez, Cesar; Hernandez, Lorenzo

    2001-01-01

    A new family of non critical bosonic string backgrounds in arbitrary space-time dimension D and with ISO(1,D-2) Poincare invariance are presented. The metric warping factor and dilaton agree asymptotically with the linear dilaton background. The closed string tachyon equation of motion enjoys, in the linear approximation, an exact solution of 'kink' type interpolating between different expectation values. A renormalization group flow interpretation, based on a closed string tachyon potential of type -T 2 e -T , is suggested

  11. On background-independent open-string field theory

    International Nuclear Information System (INIS)

    Witten, E.

    1992-01-01

    A framework for background-independent open-string field theory is proposed. The approach involves using the Batalin-Vilkovisky formalism, in a way suggested by recent developments in closed-string field theory, to implicitly define a gauge-invariant Lagrangian in a hypothetical ''space of all open-string world-sheet theories.'' It is built into the formalism that classical solutions of the string field theory are Becchi-Rouet-Stora-Tyutin- (BRST-) invariant open-string world-sheet theories and that, when expanding around a classical solution, the infinitesimal gauge transformations are generated by the world-sheet BRST operator

  12. Comments on the symmetry of AdS6 solutions in string/M-theory and Killing spinor equations

    Directory of Open Access Journals (Sweden)

    Hyojoong Kim

    2016-09-01

    Full Text Available It was recently pointed out in [1] that AdS6 solutions in IIB theory enjoy an extended symmetry structure and the consistent truncation to D=4 internal space leads to a nonlinear sigma model with target SL(3,R/SO(2,1. We continue to study the purely bosonic D=4 effective action, and elucidate how the addition of scalar potential term still allows Killing spinor equations in the absence of gauge fields. In particular, the potential turns out to be a single diagonal component of the coset representative. Furthermore, we perform a general analysis of the integrability conditions of Killing spinor equations and establish that the effective action can be in fact generalized to arbitrary sizes and signatures, e.g. with target SL(n,R/SO(p,n−p and the scalar potential expressible by a single diagonal component of the coset representative. We also comment on a similar construction and its generalizations of effective D=5 purely bosonic non-linear sigma model action related to AdS6 in M-theory.

  13. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    International Nuclear Information System (INIS)

    Villanueva, J. R.; Olivares, Marco

    2015-01-01

    Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics

  14. Dimensional reduction of 10d heterotic string effective lagrangian with higher derivative terms

    International Nuclear Information System (INIS)

    Lalak, Z.; Pawelczyk, J.

    1989-11-01

    Dimensional reduction of the 10d Supergravity-Yang-Mills theories containing up to four derivatives is described. Unexpected nondiagonal corrections to 4d gauge kinetic function and negative contributions to scalar potential are found. We analyzed the general structure of the resulting lagrangian and discuss the possible phenomenological consequences. (author)

  15. An example of higher weight superpotential interaction in the heterotic string on orbifolds

    International Nuclear Information System (INIS)

    Erdenebayar, D.

    1994-11-01

    An explicit orbifold example of the non-zero correlation functions related to the additional contribution to the induced mass term for Higgs particles at low energies is given. We verify that they form finite dimensional representations of the target space modular transformation SL 2 (Z). This action of the modular group is shown to be consistent with its action on the fixed points set defining the twisted fields. (author). 11 refs

  16. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Olivares, Marco [Universidad Diego Portales, Avenida Ejercito Libertador 441, Facultad de Ingenieria, Santiago (Chile)

    2015-11-15

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)

  17. Cosmology from string theory

    International Nuclear Information System (INIS)

    Anchordoqui, Luis; Nawata, Satoshi; Goldberg, Haim; Nunez, Carlos

    2007-01-01

    We explore the cosmological content of Salam-Sezgin six-dimensional supergravity, and find a solution to the field equations in qualitative agreement with observation of distant supernovae, primordial nucleosynthesis abundances, and recent measurements of the cosmic microwave background. The carrier of the acceleration in the present de Sitter epoch is a quintessence field slowly rolling down its exponential potential. Intrinsic to this model is a second modulus which is automatically stabilized and acts as a source of cold dark matter, with a mass proportional to an exponential function of the quintessence field (hence realizing varying mass particle models within a string context). However, any attempt to saturate the present cold dark matter component in this manner leads to unacceptable deviations from cosmological data--a numerical study reveals that this source can account for up to about 7% of the total cold dark matter budget. We also show that (1) the model will support a de Sitter energy in agreement with observation at the expense of a miniscule breaking of supersymmetry in the compact space; (2) variations in the fine structure constant are controlled by the stabilized modulus and are negligible; (3) ''fifth'' forces are carried by the stabilized modulus and are short range; (4) the long time behavior of the model in four dimensions is that of a Robertson-Walker universe with a constant expansion rate (w=-1/3). Finally, we present a string theory background by lifting our six-dimensional cosmological solution to ten dimensions

  18. Minimal string theories and integrable hierarchies

    Science.gov (United States)

    Iyer, Ramakrishnan

    -perturbative definition for the first time. Notably, we discover that the Painleve IV equation plays a key role in organizing the string theory physics, joining its siblings, Painleve I and II, whose roles have previously been identified in this minimal string context. We then present evidence that the conjectured type II theories have smooth non-perturbative solutions, connecting two perturbative asymptotic regimes, in a 't Hooft limit. Our technique also demonstrates evidence for new minimal string theories that are not apparent in a perturbative analysis.

  19. Hagedorn Behavior of Little String Theories from string corrections to NS5-branes

    DEFF Research Database (Denmark)

    Harmark, Troels; Obers, N. A.

    2000-01-01

    We examine the Hagedorn behavior of little string theory using its conjectured duality with near-horizon NS5-branes. In particular, by studying the string-corrected NS5-brane supergravity solution, it is shown that tree-level corrections to the temperature vanish, while the leading one-loop string...... correction generates the correct temperature dependence of the entropy near the Hagedorn temperature. Finally, the Hagedorn behavior of ODp-brane theories, which are deformed versions of little string theory, is considered via their supergravity duals....

  20. Supersymmetric gauge theories from string theory

    International Nuclear Information System (INIS)

    Metzger, St.

    2005-12-01

    This thesis presents various ways to construct four-dimensional quantum field theories from string theory. In a first part we study the generation of a supersymmetric Yang-Mills theory, coupled to an adjoint chiral superfield, from type IIB string theory on non-compact Calabi-Yau manifolds, with D-branes wrapping certain sub-cycles. Properties of the gauge theory are then mapped to the geometric structure of the Calabi-Yau space. Even if the Calabi-Yau geometry is too complicated to evaluate the geometric integrals explicitly, one can then always use matrix model perturbation theory to calculate the effective superpotential. The second part of this work covers the generation of four-dimensional super-symmetric gauge theories, carrying several important characteristic features of the standard model, from compactifications of eleven-dimensional supergravity on G 2 -manifolds. If the latter contain conical singularities, chiral fermions are present in the four-dimensional gauge theory, which potentially lead to anomalies. We show that, locally at each singularity, these anomalies are cancelled by the non-invariance of the classical action through a mechanism called 'anomaly inflow'. Unfortunately, no explicit metric of a compact G 2 -manifold is known. Here we construct families of metrics on compact weak G 2 -manifolds, which contain two conical singularities. Weak G 2 -manifolds have properties that are similar to the ones of proper G 2 -manifolds, and hence the explicit examples might be useful to better understand the generic situation. Finally, we reconsider the relation between eleven-dimensional supergravity and the E 8 x E 8 -heterotic string. This is done by carefully studying the anomalies that appear if the supergravity theory is formulated on a ten-manifold times the interval. Again we find that the anomalies cancel locally at the boundaries of the interval through anomaly inflow, provided one suitably modifies the classical action. (author)

  1. The cosmological constant in the brane world of string theory on S{sup 1}/Z{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wang Anzhong [GCAP-CASPER, Department of Physics, Baylor University, Waco, TX 76798-7316 (United States); Department of Theoretical Physics, State University of Rio de Janeiro, RJ (Brazil); LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris cedex 05 (France)], E-mail: anzhong_wang@baylor.edu; Santos, N.O. [LERMA/CNRS-FRE 2460, Universite Pierre et Marie Curie, ERGA, Boite 142, 4 Place Jussieu, 75005 Paris cedex 05 (France); School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil)

    2008-11-06

    Orbifold branes in string theory are investigated, and the general field equations both outside and on the branes are given explicitly for type II and heterotic string. The radion stability is studied using the Goldberger-Wise mechanism, and shown explicitly that it is stable. It is also found that the effective cosmological constant on each of the two branes can be easily lowered to its current observational value, using large extra dimensions. This is also true for type I string. Therefore, brane world of string theory provides a viable and built-in mechanism for solving the long-standing cosmological constant problem. Applying the formulas to cosmology, we obtain the generalized Friedmann equations on the branes.

  2. Relativistic classical strings. II

    International Nuclear Information System (INIS)

    Galvao, C.A.P.

    1985-01-01

    The interactions of strings with electromagnetic and gravitational fields are extensively discussed. Some concepts of differential geometry are reviewed. Strings in Kaluza-Klein manifolds are studied. (L.C.) [pt

  3. Inflationary string theory?

    Indian Academy of Sciences (India)

    strongly motivate a detailed search for inflation within string theory, although it has ... between string theory and observations provides a strong incentive for ..... sonably be expected to arise for any system having very many degrees of freedom.

  4. Chronology protection in string theory

    International Nuclear Information System (INIS)

    Dyson, Lisa

    2004-01-01

    Many solutions of General Relativity appear to allow the possibility of time travel. This was initially a fascinating discovery, but geometries of this type violate causality, a basic physical law which is believed to be fundamental. Although string theory is a proposed fundamental theory of quantum gravity, geometries with closed timelike curves have resurfaced as solutions to its low energy equations of motion. In this paper, we will study the class of solutions to low energy effective supergravity theories related to the BMPV black hole and the rotating wave-D1-D5-brane system. Time travel appears to be possible in these geometries. We will attempt to build the causality violating regions and propose that stringy effects prohibit their construction. The proposed chronology protection agent for these geometries mirrors a mechanism string theory employs to resolve a class of naked singularities. (author)

  5. Strings in the Sun?

    International Nuclear Information System (INIS)

    Chudnovsky, E.; Vilenkin, A.

    1988-01-01

    If light superconducting strings were formed in the early Universe, then it is very likely that now they exist in abundance in the interstellar plasma and in stars. The dynamics of such strings can be dominated by friction, so that they are ''frozen'' into the plasma. Turbulence of the plasma twists and stretches the strings, forming a stochastic string network. Such networks must generate particles and magnetic fields, and may play an important role in the physics of stars and of the Galaxy

  6. Why string theory?

    CERN Document Server

    Conlon, Joseph

    2016-01-01

    Is string theory a fraud or one of the great scientific advances? Why do so many physicists work on string theory if it cannot be tested? This book provides insight into why such a theory, with little direct experimental support, plays such a prominent role in theoretical physics. The book gives a modern and accurate account of string theory and science, explaining what string theory is, why it is regarded as so promising, and why it is hard to test.

  7. pp wave big bangs: Matrix strings and shrinking fuzzy spheres

    International Nuclear Information System (INIS)

    Das, Sumit R.; Michelson, Jeremy

    2005-01-01

    We find pp wave solutions in string theory with null-like linear dilatons. These provide toy models of big bang cosmologies. We formulate matrix string theory in these backgrounds. Near the big bang 'singularity', the string theory becomes strongly coupled but the Yang-Mills description of the matrix string is weakly coupled. The presence of a second length scale allows us to focus on a specific class of non-Abelian configurations, viz. fuzzy cylinders, for a suitable regime of parameters. We show that, for a class of pp waves, fuzzy cylinders which start out big at early times dynamically shrink into usual strings at sufficiently late times

  8. Random surfaces and strings

    International Nuclear Information System (INIS)

    Ambjoern, J.

    1987-08-01

    The theory of strings is the theory of random surfaces. I review the present attempts to regularize the world sheet of the string by triangulation. The corresponding statistical theory of triangulated random surfaces has a surprising rich structure, but the connection to conventional string theory seems non-trivial. (orig.)

  9. Dynamics of Carroll strings

    Energy Technology Data Exchange (ETDEWEB)

    Cardona, Biel [Departament d’Estructura i Constituents de la Matèriaand Institut de Ciències del Cosmos (ICCUB) Facultat de Física, Universitat de Barcelona,Diagonal 647, E-08028 Barcelona, Catalonia (Spain); Gomis, Joaquim [Departament d’Estructura i Constituents de la Matèriaand Institut de Ciències del Cosmos (ICCUB) Facultat de Física, Universitat de Barcelona,Diagonal 647, E-08028 Barcelona, Catalonia (Spain); Department of Physics, Faculty of Science, Chulalongkorn University,Bangkok 10330 (Thailand); Pons, Josep M. [Departament d’Estructura i Constituents de la Matèriaand Institut de Ciències del Cosmos (ICCUB) Facultat de Física, Universitat de Barcelona,Diagonal 647, E-08028 Barcelona, Catalonia (Spain)

    2016-07-11

    We construct the canonical action of a Carroll string doing the Carroll limit of a canonical relativistic string. We also study the Killing symmetries of the Carroll string, which close under an infinite dimensional algebra. The tensionless limit and the Carroll p-brane action are also discussed.

  10. String Math 2017

    CERN Document Server

    The series of String-Math conferences has developed into a central event on the interface between mathematics and physics related to string theory, quantum field theory and neighboring subjects. The conference will take place from July 24-28 in the main building of Hamburg university. The String-Math conference is organised by the University of Hamburg jointly with DESY Hamburg.

  11. Open string theory in 1+1 dimensions

    International Nuclear Information System (INIS)

    Bershadsky, M.; Kutasov, D.

    1992-01-01

    We show that tree level open two dimensional string theory is exactly solvable; the solution exhibits some unusual features, and is qualitatively different from the closed case. The open string 'tachyon' S-matrix describes free fermions, which can be interpreted as the quarks at the ends of the string. These 'quarks' live naturally on a lattice in space-time. We also find an exact vacuum solution of the theory, corresponding to a charged black hole. (orig.)

  12. Exact string theory model of closed timelike curves and cosmological singularities

    International Nuclear Information System (INIS)

    Johnson, Clifford V.; Svendsen, Harald G.

    2004-01-01

    We study an exact model of string theory propagating in a space-time containing regions with closed timelike curves (CTCs) separated from a finite cosmological region bounded by a big bang and a big crunch. The model is an nontrivial embedding of the Taub-NUT geometry into heterotic string theory with a full conformal field theory (CFT) definition, discovered over a decade ago as a heterotic coset model. Having a CFT definition makes this an excellent laboratory for the study of the stringy fate of CTCs, the Taub cosmology, and the Milne/Misner-type chronology horizon which separates them. In an effort to uncover the role of stringy corrections to such geometries, we calculate the complete set of α ' corrections to the geometry. We observe that the key features of Taub-NUT persist in the exact theory, together with the emergence of a region of space with Euclidean signature bounded by timelike curvature singularities. Although such remarks are premature, their persistence in the exact geometry is suggestive that string theory is able to make physical sense of the Milne/Misner singularities and the CTCs, despite their pathological character in general relativity. This may also support the possibility that CTCs may be viable in some physical situations, and may be a natural ingredient in pre-big bang cosmological scenarios

  13. Cosmic strings and inflation

    International Nuclear Information System (INIS)

    Vishniac, E.T.

    1987-01-01

    We examine the compatibility of inflation with the cosmic string theory for galaxy formation. There is a general conflict between having sufficient string tension to effect galaxy formation, and reheating after inflation to a high enough temperature that strings may form in a thermal phase transition. To escape this conflict, we propose a class of models where the inflation is coupled to the string-producing field. The strings are formed late in inflation as the inflaton rolls towards its zero-temperature value. A large subset of these models have a novel large-scale distribution of galaxies that is fractal, displays biasing without dynamics or feedback mechanisms, and contains voids. (orig.)

  14. Minimal open strings

    International Nuclear Information System (INIS)

    Hosomichi, Kazuo

    2008-01-01

    We study FZZT-branes and open string amplitudes in (p, q) minimal string theory. We focus on the simplest boundary changing operators in two-matrix models, and identify the corresponding operators in worldsheet theory through the comparison of amplitudes. Along the way, we find a novel linear relation among FZZT boundary states in minimal string theory. We also show that the boundary ground ring is realized on physical open string operators in a very simple manner, and discuss its use for perturbative computation of higher open string amplitudes.

  15. Critical string wave equations and the QCD (U(N{sub c})) string. (Some comments)

    Energy Technology Data Exchange (ETDEWEB)

    Botelho, Luiz C.L. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Matematica. Dept. de Matematica Aplicada], e-mail: botelho.luiz@superig.com.br

    2009-07-01

    We present a simple proof that self-avoiding fermionic strings solutions solve formally (in a Quantum Mechanical Framework) the QCD(U(N{sub c})) loop wave equation written in terms of random loops. (author)

  16. Closed Strings From Nothing

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, Albion

    2001-07-25

    We study the physics of open strings in bosonic and type II string theories in the presence of unstable D-branes. When the potential energy of the open string tachyon is at its minimum, Sen has argued that only closed strings remain in the perturbative spectrum. We explore the scenario of Yi and of Bergman, Hori and Yi, who argue that the open string degrees of freedom are strongly coupled and disappear through confinement. We discuss arguments using open string field theory and worldsheet boundary RG flows, which seem to indicate otherwise. We then describe a solitonic excitation of the open string tachyon and gauge field with the charge and tension of a fundamental closed string. This requires a double scaling limit where the tachyon is taken to its minimal value and the electric field is taken to its maximum value. The resulting flux tube has an unconstrained spatial profile; and for large fundamental string charge, it appears to have light, weakly coupled open strings living in the core. We argue that the flux tube acquires a size or order {alpha}' through sigma model and string coupling effects; and we argue that confinement effects make the light degrees of freedom heavy and strongly interacting.

  17. Closed Strings From Nothing

    International Nuclear Information System (INIS)

    Lawrence, Albion

    2001-01-01

    We study the physics of open strings in bosonic and type II string theories in the presence of unstable D-branes. When the potential energy of the open string tachyon is at its minimum, Sen has argued that only closed strings remain in the perturbative spectrum. We explore the scenario of Yi and of Bergman, Hori and Yi, who argue that the open string degrees of freedom are strongly coupled and disappear through confinement. We discuss arguments using open string field theory and worldsheet boundary RG flows, which seem to indicate otherwise. We then describe a solitonic excitation of the open string tachyon and gauge field with the charge and tension of a fundamental closed string. This requires a double scaling limit where the tachyon is taken to its minimal value and the electric field is taken to its maximum value. The resulting flux tube has an unconstrained spatial profile; and for large fundamental string charge, it appears to have light, weakly coupled open strings living in the core. We argue that the flux tube acquires a size or order α' through sigma model and string coupling effects; and we argue that confinement effects make the light degrees of freedom heavy and strongly interacting

  18. The arithmetic of strings

    International Nuclear Information System (INIS)

    Freund, P.G.O.

    1988-01-01

    According to the author nobody has succeeded as yet in extracting any new numbers from string theory. This paper discusses how if one cannot get new numbers from string theory, maybe one can get new strings out of number theory. Number theory is generally regarded as the purest form of mathematics. So how can it conceivably make contact with physics which aims at describing nature? The author discusses how the connecting link of these two disciplines is provided by the compact Riemann surfaces. These appear as world sheets of interacting strings. For instance, string-string scattering at the three-loop level involves the four external strings attaching themselves to a genus three compact surface

  19. T-duality orbifolds of heterotic Narain compactifications

    Energy Technology Data Exchange (ETDEWEB)

    Nibbelink, Stefan Groot [School of Engineering and Applied Sciences, Rotterdam University of Applied Sciences,G.J. de Jonghweg 4-6, 3015 GG Rotterdam (Netherlands); Vaudrevange, Patrick K.S. [Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München,Theresienstraße 37, 80333 München (Germany); Physik Department T30, Technische Universität München,James-Franck-Straße, 85748 Garching (Germany)

    2017-04-06

    To obtain a unified framework for symmetric and asymmetric heterotic orbifold constructions we provide a systematic study of Narain compactifications orbifolded by finite order T-duality subgroups. We review the generalized vielbein that parametrizes the Narain moduli space (i.e. the metric, the B-field and the Wilson lines) and introduce a convenient basis of generators of the heterotic T-duality group. Using this we generalize the space group description of orbifolds to Narain orbifolds. This yields a unified, crystallographic description of the orbifold twists, shifts as well as Narain moduli. In particular, we derive a character formula that counts the number of unfixed Narain moduli after orbifolding. Moreover, we develop new machinery that may ultimately open up the possibility for a full classification of Narain orbifolds. This is done by generalizing the geometrical concepts of ℚ-, ℤ- and affine classes from the theory of crystallography to the Narain case. Finally, we give a variety of examples illustrating various aspects of Narain orbifolds, including novel T-folds.

  20. Topological defects in open string field theory

    Science.gov (United States)

    Kojita, Toshiko; Maccaferri, Carlo; Masuda, Toru; Schnabl, Martin

    2018-04-01

    We show how conformal field theory topological defects can relate solutions of open string field theory for different boundary conditions. To this end we generalize the results of Graham and Watts to include the action of defects on boundary condition changing fields. Special care is devoted to the general case when nontrivial multiplicities arise upon defect action. Surprisingly the fusion algebra of defects is realized on open string fields only up to a (star algebra) isomorphism.

  1. Static potential for a string with a topological term

    International Nuclear Information System (INIS)

    Zaikov, R.P.; Zlatev, S.I.

    1991-01-01

    We study the static potential for a string in (2+1)-dimensional space-time with action including a topological term. An appropriate static solution is found and the corresponding potential is obtained. Such a solution does not exist beyond a critical distance between the ends of the string. The one-loop corrections to the static potential are calculated. (orig.)

  2. Electric drill-string telemetry

    CERN Document Server

    Carcione, J M

    2003-01-01

    We design a numerical algorithm for simulation of low-frequency electric-signal transmission through a drill string. This is represented by a transmission line with varying geometrical and electromagnetic properties versus depth, depending on the characteristics of the drill-string/formation system. These properties are implicitly modeled by the series impedance and the shunt admittance of the transmission line. The differential equations are parabolic, since at low frequencies the wave field is diffusive. We use an explicit scheme for the solution of parabolic problems, based on a Chebyshev expansion of the evolution operator and the Fourier pseudospectral method to compute the spatial derivatives. The results are verified by comparison to analytical solutions obtained for the initial-value problem with a voltage source.

  3. Dynamics of Strings in Noncommutative Gauge Theory

    International Nuclear Information System (INIS)

    Gross, David J.; Nekrasov, Nikia A.

    2000-01-01

    We continue our study of solitons in noncommutative gauge theories and present an extremely simple BPS solution of N=4 U(1) noncommutative gauge theory in 4 dimensions, which describes N infinite D1 strings that pierce a D3 brane at various points, in the presence of a background B-field in the Seiberg-Witten limit. We call this solution the N-fluxon. For N=1 we calculate the complete spectrum of small fluctuations about the fluxon and find three kinds of modes: the fluctuations of the superstring in 10 dimensions arising from fundamental strings attached to the D1 strings, the ordinary particles of the gauge theory in 4 dimensions and a set of states with discrete spectrum, localized at the intersection point - corresponding to fundamental strings stretched between the D1 string and the D3 brane. We discuss the fluctuations about the N-fluxon as well and derive explicit expressions for the amplitudes of interactions between these various modes. We show that translations in noncommutative gauge theories are equivalent to gauge transformations (plus a constant shift of the gauge field) and discuss the implications for the translational zeromodes of our solitons. We also find the dyonic versions of N-fluxon, as well as of our previous string-monopole solution. (author)

  4. New Higgs transitions between dual N=2 string models

    International Nuclear Information System (INIS)

    Berglund, P.; Katz, S.; Klemm, A.; Mayr, P.

    1997-01-01

    We describe a new kind of transition between topologically distinct N=2 type II Calabi-Yau vacua through points with enhanced non-abelian gauge symmetries together with fundamental charged matter hyper multiplets. We connect the appearance of matter to the local geometry of the singularity and discuss the relation between the instanton numbers of the Calabi-Yau manifolds taking part in the transition. In a dual heterotic string theory on K3 x T 2 the process corresponds to Higgsing a semi-classical gauge group or equivalently to a variation of the gauge bundle. In special cases the situation reduces to simple conifold transitions in the Coulomb phase of the non-abelian gauge symmetries. (orig.)

  5. Zamolodchikov's c-theorem and string effective actions

    International Nuclear Information System (INIS)

    Mavromatos, N.E.; Miramontes, J.L.

    1988-01-01

    Zamolodchikov's c-theorem for 2D renormalisable field theories is presented in a way which allows for a straightforward application to the case of bosonic σ-models. As a consistency check in the latter case, the Curci-Paffuti relation is rederived. It is also shown that the 'metric' in coupling constant space in this case is a c-number function of the backgrounds. Attempts to derive off-shell functional relations between the Weyl anomaly coefficients and field variations of string effective actions, compatible with the c-theorem, are discussed by emphasising the necessity of performing explicit perturbative calculations in order to arrive at definite conclusions. Comments concerning the extension of the c-theorem to the case of supersymmetric and heterotic σ-models are also made. (orig.)

  6. BRST invariant mixed string vertex for the bosonic string

    International Nuclear Information System (INIS)

    Clarizia, A.; Pezzella, F.

    1987-09-01

    We construct a BRST invariant (N+M)-string vertex including both open and closed string states. When we saturate it with N open string and M closed string physical states it reproduces their corresponding scattering amplitude. As a particular case we obtain BRST invariant vertex for the open-closed string transition. (orig.)

  7. Open-closed string correspondence in open string field theory

    International Nuclear Information System (INIS)

    Baumgartl, M.; Sachs, I.

    2008-01-01

    We address the problem of describing different closed string backgrounds in background independent open string field theory: A shift in the closed string background corresponds to a collective excitation of open strings. As an illustration we apply the formalism to the case where the closed string background is a group manifold. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  8. The search for a realistic flipped SU(5) string model

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J.L. (Center for Theoretical Physics, Texas A and M Univ., College Station, TX (United States) Astroparticle Physics Group, Houston Advanced Research Center (HARC), The Woodlands, TX (United States)); Nanopoulos, D.V. (Center for Theoretical Physics, Texas A and M Univ., College Station, TX (United States) Astroparticle Physics Group, Houston Advanced Research Center (HARC), The Woodlands, TX (United States)); Yuan, K. (Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL (United States))

    1993-07-05

    We present an extensive search for a class of flipped SU(5) models built within the free fermionic formulation of the heterotic string. We describe a set of algorithms which constitute the basis for a computer program capable of generating systematically the massless spectrum and the superpotential of all possible models within the class we consider. Our search through the huge parameter space to be explored is simplified considerably by the constraint of N=1 spacetime supersymmetry and the need for extra Q, anti Q representations beyond the standard ones in order to possibly achieve string gauge coupling unification at scales of O(10[sup 18] GeV). Our results are remarkably simple and evidence the large degree of redundancy in this kind of constructions. We find one model with gauge group SU(5)xU(1)sub(Y tilde)xSO(10)[sub h]xSU(4)[sub h]xU(1)[sup 5] and fairly acceptable phenomenological properties. We study the D- and F-flatness constraints and the symmetry breaking pattern in this model and conclude that string gauge coupling unification is quite possible. (orig.)

  9. Lie algebra lattices and strings on T-folds

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Yuji [Institute of Physics, University of Tsukuba,Ibaraki 305-8571 (Japan); Sugawara, Yuji [Department of Physical Sciences, College of Science and Engineering, Ritsumeikan University,Shiga 525-8577 (Japan)

    2017-02-06

    We study the world-sheet conformal field theories for T-folds systematically based on the Lie algebra lattices representing the momenta of strings. The fixed point condition required for the T-duality twist restricts the possible Lie algebras. When the T-duality acts as a simple chiral reflection, one is left with the four cases, A{sub 1},D{sub 2r},E{sub 7},E{sub 8}, among the simple simply-laced algebras. From the corresponding Englert-Neveu lattices, we construct the modular invariant partition functions for the T-fold CFTs in bosonic string theory. Similar construction is possible also by using Euclidean even self-dual lattices. We then apply our formulation to the T-folds in the E{sub 8}×E{sub 8} heterotic string theory. Incorporating non-trivial phases for the T-duality twist, we obtain, as simple examples, a class of modular invariant partition functions parametrized by three integers. Our construction includes the cases which are not reduced to the free fermion construction.

  10. Strings, texture, and inflation

    International Nuclear Information System (INIS)

    Hodges, H.M.; Primack, J.R.

    1991-01-01

    We examine mechanisms, several of which are proposed here, to generate structure formation, or to just add large-scale features, through either gauged or global cosmic strings or global texture, within the framework of inflation. We first explore the possibility that strings or texture form if there is no coupling between the topological theory and the inflaton or spacetime curvature, via (1) quantum creation, and (2) a sufficiently high reheat temperature. In addition, we examine the prospects for the inflaton field itself to generate strings or texture. Then, models with the string/texture field coupled to the curvature, and an equivalent model with coupling to the inflaton field, are considered in detail. The requirement that inflationary density fluctuations are not so large as to conflict with observations leads to a number of constraints on model parameters. We find that strings of relevance for structure formation can form in the absence of coupling to the inflaton or curvature through the process of quantum creation, but only if the strings are strongly type I, or if they are global strings. If formed after reheating, naturalness suggests that gauged cosmic strings correspond to a type-I superconductor. Similarly, gauged strings formed during inflation via conformal coupling ξ=1/6 to the spacetime curvature (in a model suggested by Yokoyama in order to evade the millisecond pulsar constraint on cosmic strings) are expected to be strongly type I

  11. Document retrieval on repetitive string collections.

    Science.gov (United States)

    Gagie, Travis; Hartikainen, Aleksi; Karhu, Kalle; Kärkkäinen, Juha; Navarro, Gonzalo; Puglisi, Simon J; Sirén, Jouni

    2017-01-01

    Most of the fastest-growing string collections today are repetitive, that is, most of the constituent documents are similar to many others. As these collections keep growing, a key approach to handling them is to exploit their repetitiveness, which can reduce their space usage by orders of magnitude. We study the problem of indexing repetitive string collections in order to perform efficient document retrieval operations on them. Document retrieval problems are routinely solved by search engines on large natural language collections, but the techniques are less developed on generic string collections. The case of repetitive string collections is even less understood, and there are very few existing solutions. We develop two novel ideas, interleaved LCPs and precomputed document lists , that yield highly compressed indexes solving the problem of document listing (find all the documents where a string appears), top- k document retrieval (find the k documents where a string appears most often), and document counting (count the number of documents where a string appears). We also show that a classical data structure supporting the latter query becomes highly compressible on repetitive data. Finally, we show how the tools we developed can be combined to solve ranked conjunctive and disjunctive multi-term queries under the simple [Formula: see text] model of relevance. We thoroughly evaluate the resulting techniques in various real-life repetitiveness scenarios, and recommend the best choices for each case.

  12. Cosmic strings in an expanding spacetime

    International Nuclear Information System (INIS)

    Stein-Schabes, J.A.; Burd, A.B.

    1987-04-01

    We investigate the stability of a static, infinitely long and straight vacuum string solution under inhomogeneous axisymmetric time-dependent perturbations. We find it to be perturbatively stable. We further extend our work by finding a string solutions in an expanding Universe. The back reaction of the string on the gravitational field has been ignored. The background is assumed to be a Friedman-Robertson-Walker (FRW) cosmology. By numerically integrating the field equations in a radiation and matter dominated models, we discover oscillatory solutions. The possible damping of these oscillations is discussed. For late times the solution becomes identical to the static one studied in the first part of the paper. 19 refs., 8 figs

  13. The stability of D-term cosmic strings

    International Nuclear Information System (INIS)

    Collinucci, A.; Smyth, P.; Van Proeyen, A.

    2007-01-01

    In this article, we discuss the semi-classical stability of the D-term string solution of D=4, N=1 supergravity with a constant Fayet-Iliopoulos term. Regardless of the particular theory one is interested in, the stability of cosmic strings is necessary if we hope to observe them. We apply the spinorial Witten-Nester method to prove a positive energy theorem for the D-term cosmic string background with positive deficit angle. We also pay particular attention to the negative deficit angle D-term string, which is known to violate the dominant energy condition. Within the class of string solutions we consider, this violation implies that the negative deficit angle D-term string must have a naked pathology and therefore the positive energy theorem we prove does not apply to it. (orig.)

  14. Strings and quantum gravity

    International Nuclear Information System (INIS)

    Vega, H.J. de

    1990-01-01

    One of the main challenges in theoretical physics today is the unification of all interactions including gravity. At present, string theories appear as the most promising candidates to achieve such a unification. However, gravity has not completely been incorporated in string theory, many technical and conceptual problems remain and a full quantum theory of gravity is still non-existent. Our aim is to properly understand strings in the context of quantum gravity. Attempts towards this are reviewed. (author)

  15. ABCD of Beta Ensembles and Topological Strings

    CERN Document Server

    Krefl, Daniel

    2012-01-01

    We study beta-ensembles with Bn, Cn, and Dn eigenvalue measure and their relation with refined topological strings. Our results generalize the familiar connections between local topological strings and matrix models leading to An measure, and illustrate that all those classical eigenvalue ensembles, and their topological string counterparts, are related one to another via various deformations and specializations, quantum shifts and discrete quotients. We review the solution of the Gaussian models via Macdonald identities, and interpret them as conifold theories. The interpolation between the various models is plainly apparent in this case. For general polynomial potential, we calculate the partition function in the multi-cut phase in a perturbative fashion, beyond tree-level in the large-N limit. The relation to refined topological string orientifolds on the corresponding local geometry is discussed along the way.

  16. Introduction to string and superstring theory II

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1987-03-01

    Conformal field theory is reviewed, then conformal invariance is used to rederive the basic results on the embedding dimensionality for bosonic and fermionic strings. The spectrum of the bosonic and the computation of scattering amplitudes are discussed. The formalism used is extended to clarify the origin of Yang-Mills gauge invariance in the open bosonic string theory. The question of the general-coordinate gauge invariance of string theory is addressed, presenting two disparate viewpoints on this question. A brief introduction is then given of the reduction from the idealized string theory in 10 extended dimensions to more realistic solutions in which all but 4 of these dimensions are compactified. The state of knowledge about the space-time supersymmetry of the superstring from the covariant viewpoint is outlined. An approach for identifying possible 6-dimensional spaces which might represent the form of the compact dimensions is discussed, and the orbifold scheme of compactification is presented. 77 refs., 18 figs

  17. Introduction to string and superstring theory II

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E.

    1987-03-01

    Conformal field theory is reviewed, then conformal invariance is used to rederive the basic results on the embedding dimensionality for bosonic and fermionic strings. The spectrum of the bosonic and the computation of scattering amplitudes are discussed. The formalism used is extended to clarify the origin of Yang-Mills gauge invariance in the open bosonic string theory. The question of the general-coordinate gauge invariance of string theory is addressed, presenting two disparate viewpoints on this question. A brief introduction is then given of the reduction from the idealized string theory in 10 extended dimensions to more realistic solutions in which all but 4 of these dimensions are compactified. The state of knowledge about the space-time supersymmetry of the superstring from the covariant viewpoint is outlined. An approach for identifying possible 6-dimensional spaces which might represent the form of the compact dimensions is discussed, and the orbifold scheme of compactification is presented. 77 refs., 18 figs. (LEW)

  18. 6d string chains

    Science.gov (United States)

    Gadde, Abhijit; Haghighat, Babak; Kim, Joonho; Kim, Seok; Lockhart, Guglielmo; Vafa, Cumrun

    2018-02-01

    We consider bound states of strings which arise in 6d (1,0) SCFTs that are realized in F-theory in terms of linear chains of spheres with negative self-intersections 1,2, and 4. These include the strings associated to N small E 8 instantons, as well as the ones associated to M5 branes probing A and D type singularities in M-theory or D5 branes probing ADE singularities in Type IIB string theory. We find that these bound states of strings admit (0,4) supersymmetric quiver descriptions and show how one can compute their elliptic genera.

  19. QCD and string theories

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, G.

    1990-01-01

    This paper is devoted to a review of the connections between quantumchromodynamics (QCD) and string theories. One reviews the phenomenological models leading to string pictures in non perturbative QCD and the string effects, related to soft gluon coherence, which arise in perturbative QCD. One tries to build a string theory which goes to QCD at the zero slope limit. A specific model, based on superstring theories is shown to agree with QCD four point amplitudes at the Born approximation and with one loop corrections. One shows how this approach can provide a theoretical framework to account for the phenomenological property of parton-hadron duality

  20. Thermodynamics of quantum strings

    CERN Document Server

    Morgan, M J

    1994-01-01

    A statistical mechanical analysis of an ideal gas of non-relativistic quantum strings is presented, in which the thermodynamic properties of the string gas are calculated from a canonical partition function. This toy model enables students to gain insight into the thermodynamics of a simple 'quantum field' theory, and provides a useful pedagogical introduction to the more complicated relativistic string theories. A review is also given of the thermodynamics of the open bosonic string gas and the type I (open) superstring gas. (author)

  1. Interpolating string field theories

    International Nuclear Information System (INIS)

    Zwiebach, B.

    1992-01-01

    This paper reports that a minimal area problem imposing different length conditions on open and closed curves is shown to define a one-parameter family of covariant open-closed quantum string field theories. These interpolate from a recently proposed factorizable open-closed theory up to an extended version of Witten's open string field theory capable of incorporating on shell closed strings. The string diagrams of the latter define a new decomposition of the moduli spaces of Riemann surfaces with punctures and boundaries based on quadratic differentials with both first order and second order poles

  2. Stretching cosmic strings

    International Nuclear Information System (INIS)

    Turok, N.; Bhattacharjee, P.

    1984-01-01

    The evolution of a network of strings produced at a grand-unification phase transition in an expanding universe is discussed, with particular reference to the processes of energy exchange between the strings and the rest of the universe. This is supported by numerical calculations simulating the behavior of strings in an expanding universe. It is found that in order that the energy density of the strings does not come to dominate the total energy density there must be an efficient mechanism for energy loss: the only plausible one being the production of closed loops and their subsequent decay via gravitational radiation

  3. QCD and hadronic strings

    International Nuclear Information System (INIS)

    Cohen-Tannoudji, G.

    1989-01-01

    This series of lectures is devoted to review ot he connections between QCD and string theories. One reviews the phenomenological models leading to string pictures in non perturbative QCD and the string effects, related to soft gluon coherence, which arise in perturbative QCD. One tries to build a string theory which goes to QCD at the zero slope limit. A specific model, based on superstring theories is shown to agree with QCD four point amplitudes at the Born approximation and with one loop corrections. One shows how this approach can provide a theoretical framework to account for the phenomenological property of parton-hadron duality.(author)

  4. The Kerr geometry, complex world lines and hyperbolic strings

    International Nuclear Information System (INIS)

    Burinskii, A.Ya.

    1994-01-01

    In the Lind-Newman representation the Kerr geometry is created by a source moving along an analytical complex world line. An equivalence of the complex world line and complex (hyperbolic) string is considered. Therefore the hyperbolic string may play the role of the complex source of the Kerr geometry. The Kerr solution with the complex string source acquires Regge behavior of the angular momentum. (orig.)

  5. On SUSY breaking and χSB from string duals

    International Nuclear Information System (INIS)

    Gomis, Jaume

    2002-01-01

    We find regular string duals of three-dimensional N=1 SYM with a Chern-Simons interaction at level k for SO and Sp gauge groups. Using the string dual we exactly reproduce the conjectured pattern of supersymmetry breaking proposed by Witten by showing that there is dynamical supersymmetry breaking for k 2h →Z 2 by analyzing the symmetries of the string solution

  6. Discrete R-symmetries and anomaly universality in heterotic orbifolds

    Energy Technology Data Exchange (ETDEWEB)

    Bizet, Nana G. Cabo [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear,Calle 30, esq.a 5ta Ave, Miramar, 6122 La Habana (Cuba); Kobayashi, Tatsuo [Department of Physics, Kyoto University,Kyoto 606-8502 (Japan); Peña, Damián K. Mayorga [Bethe Center for Theoretical Physics and Physikalisches Institut der Universität Bonn,Nussallee 12, 53115 Bonn (Germany); Parameswaran, Susha L. [Department of Mathematics and Physics, Leibniz Universität Hannover,Welfengarten 1, 30167 Hannover (Germany); Schmitz, Matthias [Bethe Center for Theoretical Physics and Physikalisches Institut der Universität Bonn,Nussallee 12, 53115 Bonn (Germany); Zavala, Ivonne [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2014-02-24

    We study discrete R-symmetries, which appear in the 4D low energy effective field theory derived from heterotic orbifold models. We derive the R-symmetries directly from the geometrical symmetries of the orbifolds. In particular, we obtain the corresponding R-charges by requiring that the couplings be invariant under these symmetries. This allows for a more general treatment than the explicit computations of correlation functions made previously by the authors, including models with discrete Wilson lines, and orbifold symmetries beyond plane-by-plane rotational invariance. The R-charges obtained in this manner differ from those derived in earlier explicit computations. We study the anomalies associated with these R-symmetries, and comment on the results.

  7. Abstraction/Representation Theory for heterotic physical computing.

    Science.gov (United States)

    Horsman, D C

    2015-07-28

    We give a rigorous framework for the interaction of physical computing devices with abstract computation. Device and program are mediated by the non-logical representation relation; we give the conditions under which representation and device theory give rise to commuting diagrams between logical and physical domains, and the conditions for computation to occur. We give the interface of this new framework with currently existing formal methods, showing in particular its close relationship to refinement theory, and the implications for questions of meaning and reference in theoretical computer science. The case of hybrid computing is considered in detail, addressing in particular the example of an Internet-mediated social machine, and the abstraction/representation framework used to provide a formal distinction between heterotic and hybrid computing. This forms the basis for future use of the framework in formal treatments of non-standard physical computers. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  8. Solving the decompactification problem in string theory

    CERN Document Server

    Kiritsis, Elias B; Petropoulos, P M; Rizos, J

    1996-01-01

    We investigate heterotic ground states in four dimensions in which N=4 supersymmetry is spontaneously broken to N=2. N=4 supersymmetry is restored at a decompactification limit corresponding to m_{3/2}\\to 0. We calculate the full moduli dependent threshold corrections and confirm that they are supressed in the decompactification limit m_{3/2}\\to 0 as expected from the restauration of N=4 supersymmetry. This should be contrasted with the behavior of the standard N=2 groundstates where the coupling blow up linearly with the volume of the decompactifying manifold. This mechanism provides a solution to the decompactification problem for the gauge coupling constants. We also discuss how the mechanism can be implemented in ground states with lower supersymmetry.

  9. Rotating black string with nonlinear source

    International Nuclear Information System (INIS)

    Hendi, S. H.

    2010-01-01

    In this paper, we derive rotating black string solutions in the presence of two kinds of nonlinear electromagnetic fields, so-called Born-Infeld and power Maxwell invariant. Investigation of the solutions show that for the Born-Infeld black string the singularity is timelike and the asymptotic behavior of the solutions is anti-de Sitter, but for power Maxwell invariant solutions, depending on the values of nonlinearity parameter, the singularity may be timelike as well as spacelike and the solutions are not asymptotically anti-de Sitter for all values of the nonlinearity parameter. Next, we calculate the conserved quantities of the solutions by using the counterterm method, and find that these quantities do not depend on the nonlinearity parameter. We also compute the entropy, temperature, the angular velocity, the electric charge, and the electric potential of the solutions, in which the conserved and thermodynamics quantities satisfy the first law of thermodynamics.

  10. De Sitter vacua in no-scale supergravities and Calabi-Yau string models

    CERN Document Server

    Covi, Laura; Gross, Christian; Louis, Jan; Palma, Gonzalo A; Scrucca, Claudio A

    2008-01-01

    We perform a general analysis on the possibility of obtaining metastable vacua with spontaneously broken N=1 supersymmetry and non-negative cosmological constant in the moduli sector of string models. More specifically, we study the condition under which the scalar partners of the Goldstino are non-tachyonic, which depends only on the Kahler potential. This condition is not only necessary but also sufficient, in the sense that all of the other scalar fields can be given arbitrarily large positive square masses if the superpotential is suitably tuned. We consider both heterotic and orientifold string compactifications in the large-volume limit and show that the no-scale property shared by these models severely restricts the allowed values for the `sGoldstino' masses in the superpotential parameter space. We find that a positive mass term may be achieved only for certain types of compactifications and specific Goldstino directions. Additionally, we show how subleading corrections to the Kahler potential which b...

  11. $\\mathcal{N}=2^\\star$ from Topological Amplitudes in String Theory

    CERN Document Server

    Florakis, Ioannis

    2016-01-01

    In this paper, we explicitly construct string theory backgrounds that realise the so-called $\\mathcal N=2^\\star$ gauge theory. We prove the consistency of our models by calculating their partition function and obtaining the correct gauge theory spectrum. We further provide arguments in favour of the universality of our construction which covers a wide class of models all of which engineer the same gauge theory. We reproduce the corresponding Nekrasov partition function once the $\\Omega$-deformation is included and the appropriate field theory limit taken. This is achieved by calculating the topological amplitudes $F_g$ in the string models. In addition to heterotic and type II constructions, we also realise the mass deformation in type I theory, thus leading to a natural way of uplifting the result to the instanton sector.

  12. Full component Lagrangian in the linear multiplet formulation of string-inspired effective supergravity

    International Nuclear Information System (INIS)

    Giedt, Joel

    2003-01-01

    We compute the component field four-dimensional N = 1 supergravity Lagrangian that is obtained from a superfield Lagrangian in the U(1) K formalism with a linear dilaton multiplet. All fermionic terms are presented. In a variety of important ways, our results generalize those that have been reported previously, and are flexible enough to accommodate many situations of phenomenological interest in string-inspired effective supergravity, especially models based on orbifold compactifications of the weakly coupled heterotic string. We provide for an effective theory of hidden gaugino and matter condensation. We include supersymmetric Green-Schwarz counterterms associated with the cancellation of U(1) and modular duality anomalies; the modular duality counterterm is of a rather general form. Our assumed form for the dilaton Kaehler potential is quite general and can accommodate Kaehler stabilization methods. We note possible applications of our results. We also discuss the usefulness of the linear dilaton formulation as a complement to the chiral dilaton approach

  13. Semilocal and electroweak strings

    NARCIS (Netherlands)

    Achucarro, A; Vachaspati, T

    We review a class of non-topological defects in the standard electroweak model, and their implications. Starting with the semilocal string, which provides a counterexample to many well-known properties of topological vortices, we discuss electroweak strings and their stability with and without

  14. Disordered chaotic strings

    DEFF Research Database (Denmark)

    Schäfer, Mirko; Greiner, Martin

    2011-01-01

    to chaotic strings. Inhomogeneous coupling weights as well as small-world perturbations of the ring-network structure are discussed. It is found that certain combinations of coupling and network disorder preserve the empirical relationship between chaotic strings and the weak and strong sector...

  15. Derandomizing from random strings

    NARCIS (Netherlands)

    Buhrman, H.; Fortnow, L.; Koucký, M.; Loff, B.

    2010-01-01

    In this paper we show that BPP is truth-table reducible to the set of Kolmogorov random strings R(K). It was previously known that PSPACE, and hence BPP is Turing-reducible to R(K). The earlier proof relied on the adaptivity of the Turing-reduction to find a Kolmogorov-random string of polynomial

  16. Optimal Packed String Matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany

    2011-01-01

    In the packed string matching problem, each machine word accommodates – characters, thus an n-character text occupies n/– memory words. We extend the Crochemore-Perrin constantspace O(n)-time string matching algorithm to run in optimal O(n/–) time and even in real-time, achieving a factor – speed...

  17. Introduction to string theory

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    I will present a simple and non-technical overview of string theory, aimed for non-experts who like to get some idea what string theory is about. Besides introductory material, I intend to cover also some of the more recent developments.

  18. StringForce

    DEFF Research Database (Denmark)

    Barendregt, Wolmet; Börjesson, Peter; Eriksson, Eva

    2017-01-01

    In this paper, we present the forced collaborative interaction game StringForce. StringForce is developed for a special education context to support training of collaboration skills, using readily available technologies and avoiding the creation of a "mobile bubble". In order to play String......Force two or four physically collocated tablets are required. These tablets are connected to form one large shared game area. The game can only be played by collaborating. StringForce extends previous work, both technologically and regarding social-emotional training. We believe String......Force to be an interesting demo for the IDC community, as it intertwines several relevant research fields, such as mobile interaction and collaborative gaming in the special education context....

  19. String-Math 2015

    CERN Document Server

    2015-01-01

    Welcome to String-Math 2015 at Sanya. The conference will be opened in December 31, 2015- January 4, 2016. String theory plays a central role in theoretical physics as a candidate for the quantum theory unifying gravity with other interactions. It has profound connections with broad branches of modern mathematics ever since the birth. In the last decades, the prosperous interaction, built upon the joint efforts from both mathematicians and physicists, has given rise to marvelous deep results in supersymmetric gauge theory, topological string, M-theory and duality on the physics side as well as in algebraic geometry, differential geometry, algebraic topology, representation theory and number theory on the mathematics side. The interplay is two-fold. The mathematics has provided powerful tools to fulfill the physical interconnection of ideas and clarify physical structures to understand the nature of string theory. On the other hand, ideas from string theory and quantum field theory have been a source of sign...

  20. Open string model building

    International Nuclear Information System (INIS)

    Ishibashi, Nobuyuki; Onogi, Tetsuya

    1989-01-01

    Consistency conditions of open string theories, which can be a powerful tool in open string model building, are proposed. By making use of these conditions and assuming a simple prescription for the Chan-Paton factors, open string theories in several backgrounds are studied. We show that 1. there exist a large number of consistent bosonic open string theories on Z 2 orbifolds, 2. SO(32) type I superstring is the unique consistent model among fermionic string theories on the ten-dimensional flat Minkowski space, and 3. with our prescription for the Chan-Paton factors, there exist no consistent open superstring theories on (six-dimensional Minkowski space-time) x (Z 2 orbifold). (orig.)

  1. Stationary closed strings in five-dimensional flat spacetime

    Science.gov (United States)

    Igata, Takahisa; Ishihara, Hideki; Nishiwaki, Keisuke

    2012-11-01

    We investigate stationary rotating closed Nambu-Goto strings in five-dimensional flat spacetime. The stationary string is defined as a world sheet that is tangent to a timelike Killing vector. The Nambu-Goto equation of motion for the stationary string is reduced to the geodesic equation on the orbit space of the isometry group action generated by the Killing vector. We take a linear combination of a time-translation vector and space-rotation vectors as the Killing vector, and explicitly construct general solutions of stationary rotating closed strings in five-dimensional flat spacetime. We show a variety of their configurations and properties.

  2. Non-static local string in Brans–Dicke theory

    Indian Academy of Sciences (India)

    Abstract. A recent investigation showed that a local gauge string with a phenomenological energy momentum tensor, as prescribed by Vilenkin, is inconsistent in Brans–Dicke theory. In this work it has been shown that such a string is indeed consistent if one introduces time dependences in the metric. A set of solutions of full ...

  3. Geometric Transitions, Topological Strings, and Generalized Complex Geometry

    International Nuclear Information System (INIS)

    Chuang, Wu-yen

    2007-01-01

    Mirror symmetry is one of the most beautiful symmetries in string theory. It helps us very effectively gain insights into non-perturbative worldsheet instanton effects. It was also shown that the study of mirror symmetry for Calabi-Yau flux compactification leads us to the territory of ''Non-Kaehlerity''. In this thesis we demonstrate how to construct a new class of symplectic non-Kaehler and complex non-Kaehler string theory vacua via generalized geometric transitions. The class admits a mirror pairing by construction. From a variety of sources, including super-gravity analysis and KK reduction on SU(3) structure manifolds, we conclude that string theory connects Calabi-Yau spaces to both complex non-Kaehler and symplectic non-Kaehler manifolds and the resulting manifolds lie in generalized complex geometry. We go on to study the topological twisted models on a class of generalized complex geometry, bi-Hermitian geometry, which is the most general target space for (2, 2) world-sheet theory with non-trivial H flux turned on. We show that the usual Kaehler A and B models are generalized in a natural way. Since the gauged supergravity is the low energy effective theory for the compactifications on generalized geometries, we study the fate of flux-induced isometry gauging in N = 2 IIA and heterotic strings under non-perturbative instanton effects. Interestingly, we find we have protection mechanisms preventing the corrections to the hyper moduli spaces. Besides generalized geometries, we also discuss the possibility of new NS-NS fluxes in a new doubled formalism

  4. Geometric Transitions, Topological Strings, and Generalized Complex Geometry

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Wu-yen; /SLAC /Stanford U., Phys. Dept.

    2007-06-29

    Mirror symmetry is one of the most beautiful symmetries in string theory. It helps us very effectively gain insights into non-perturbative worldsheet instanton effects. It was also shown that the study of mirror symmetry for Calabi-Yau flux compactification leads us to the territory of ''Non-Kaehlerity''. In this thesis we demonstrate how to construct a new class of symplectic non-Kaehler and complex non-Kaehler string theory vacua via generalized geometric transitions. The class admits a mirror pairing by construction. From a variety of sources, including super-gravity analysis and KK reduction on SU(3) structure manifolds, we conclude that string theory connects Calabi-Yau spaces to both complex non-Kaehler and symplectic non-Kaehler manifolds and the resulting manifolds lie in generalized complex geometry. We go on to study the topological twisted models on a class of generalized complex geometry, bi-Hermitian geometry, which is the most general target space for (2, 2) world-sheet theory with non-trivial H flux turned on. We show that the usual Kaehler A and B models are generalized in a natural way. Since the gauged supergravity is the low energy effective theory for the compactifications on generalized geometries, we study the fate of flux-induced isometry gauging in N = 2 IIA and heterotic strings under non-perturbative instanton effects. Interestingly, we find we have protection mechanisms preventing the corrections to the hyper moduli spaces. Besides generalized geometries, we also discuss the possibility of new NS-NS fluxes in a new doubled formalism.

  5. Cylindrically symmetric, static strings with a cosmological constant in Brans-Dicke theory

    International Nuclear Information System (INIS)

    Delice, Oezguer

    2006-01-01

    The static cylindrically symmetric vacuum solutions with a cosmological constant in the framework of the Brans-Dicke theory are investigated. Some of these solutions admitting Lorentz boost invariance along the symmetry axis correspond to local, straight cosmic strings with a cosmological constant. Some physical properties of such solutions are studied. These strings apply attractive or repulsive forces on the test particles. A smooth matching is also performed with a recently introduced interior thick string solution with a cosmological constant

  6. A reduced covariant string model for the extrinsic string

    International Nuclear Information System (INIS)

    Botelho, L.C.L.

    1989-01-01

    It is studied a reduced covariant string model for the extrinsic string by using Polyakov's path integral formalism. On the basis of this reduced model it is suggested that the extrinsic string has its critical dimension given by 13. Additionally, it is calculated in a simple way Poliakov's renormalization group law for the string rigidity coupling constants. (A.C.A.S.) [pt

  7. Early reheating and cosmic strings

    International Nuclear Information System (INIS)

    Stebbins, A.J. III.

    1987-01-01

    In the first chapter, possible thermal histories of the universe during the epoch z = 10 - 100 are studied. Expression for the fractional ionization and electron temperature are given in the case of homogeneous heating as a function of the parameters of arbitrary ionizing sources. It is shown that present and future limits on spectral distortions to the microwave background radiation do not provide very restrictive constraints on possible thermal histories of the universe. Heating by cosmic rays and very massive stars is discussed. In the second chapter, accretion of matter onto the wakes left behind by horizon-size pieces of cosmic string is studied. It was found that in a universe containing cold dissipationless matter (CDM), accretion onto wakes produce a network of sheet-like regions with a nonlinear density enhancement. In the third chapter, a formalism is developed for calculating the microwave ansisotropy produced by cosmic string loops in Minkowski space. The final formalism involves doing a one-dimensional integral along the string for each point on the sky. Exact solutions have only been found for a circular loop seen face-on. The equations are integrated for one particular loop configuration at nine points in its evolution

  8. String field theory

    International Nuclear Information System (INIS)

    Kaku, M.

    1987-01-01

    In this article, the authors summarize the rapid progress in constructing string field theory actions, such as the development of the covariant BRST theory. They also present the newer geometric formulation of string field theory, from which the BRST theory and the older light cone theory can be derived from first principles. This geometric formulation allows us to derive the complete field theory of strings from two geometric principles, in the same way that general relativity and Yang-Mills theory can be derived from two principles based on global and local symmetry. The geometric formalism therefore reduces string field theory to a problem of finding an invariant under a new local gauge group they call the universal string group (USG). Thus, string field theory is the gauge theory of the universal string group in much the same way that Yang-Mills theory is the gauge theory of SU(N). The geometric formulation places superstring theory on the same rigorous group theoretical level as general relativity and gauge theory

  9. Duality relation between charged elastic strings and superconducting cosmic strings

    International Nuclear Information System (INIS)

    Carter, B.

    1989-01-01

    The mechanical properties of macroscopic electromagnetically coupled string models in a flat or curved background are treated using a covariant formalism allowing the construction of a duality transformation that relates the category of uniform ''electric'' string models, constructed as the (nonconducting) charged generalisation of ordinary uncoupled (violin type) elastic strings, to a category of ''magnetic'' string models comprising recently discussed varieties of ''superconducting cosmic strings''. (orig.)

  10. Influenza em animais heterotérmicos Influenza in heterothermics

    Directory of Open Access Journals (Sweden)

    Dalva Assunção Portari Mancini

    2004-06-01

    Full Text Available O objetivo foi pesquisar Ortomyxovirus em animais heterotérmicos. Coletou-se sangue de serpentes dos gêneros Bothrops e Crotalus e de sapo e rãs dos gêneros Bufo e Rana, para a detecção dos receptores de hemácias e anticorpos específicos, ao vírus influenza, pelos testes de hemaglutinação e inibição da hemaglutinação, respectivamente. Pelo teste de hemaglutinação, verificou-se que serpentes e sapos em cativeiro apresentaram receptores em suas hemácias para o vírus influenza, humano e eqüino do tipo A e tipo B. O mesmo ocorreu com serpentes recém chegadas. Quanto ao teste de inibição da hemaglutinação dos soros dos répteis observou-se títulos protetores de anticorpos aos vírus influenza tipo A (origens humana e eqüina e tipo B. Com soro de sapo não se observou reação de inibição da hemaglutinação porém, 83,3% das rãs obtiveram médias de 40UIH para algumas cepas. Conclui-se que animais heterotérmicos podem oferecer condições de hospedeiros aos vírus influenza, assim como susceptibilidade à infecção.The objective was to study Orthomyxovirus in heterothermic animals. Blood samples from snakes (genus Bothrops and Crotalus and from toads and frogs (genus Bufo and Rana were collected to evaluate the red cell receptors and antibodies specific to influenza virus by the hemagglutination and hemagglutination inhibition tests, respectively. Both snakes and toads kept in captivity presented receptors in their red cells and antibodies specific to either influenza virus type A (human and equine origin or influenza type B. The same was observed with recently captured snakes. Concerning the influenza hemagglutination inhibition antibodies protective levels were observed in the reptiles' serum, against influenza type A and type B. Unlike the toads, 83.3% of the frogs presented mean levels of Ab 40HIU for some influenza strains. It was concluded that heterothermic animals could offer host conditions to the influenza

  11. Lattice gravity and strings

    International Nuclear Information System (INIS)

    Jevicki, A.; Ninomiya, M.

    1985-01-01

    We are concerned with applications of the simplicial discretization method (Regge calculus) to two-dimensional quantum gravity with emphasis on the physically relevant string model. Beginning with the discretization of gravity and matter we exhibit a discrete version of the conformal trace anomaly. Proceeding to the string problem we show how the direct approach of (finite difference) discretization based on Nambu action corresponds to unsatisfactory treatment of gravitational degrees. Based on the Regge approach we then propose a discretization corresponding to the Polyakov string. In this context we are led to a natural geometric version of the associated Liouville model and two-dimensional gravity. (orig.)

  12. Superconducting cosmic strings

    International Nuclear Information System (INIS)

    Chudnovsky, E.M.; Field, G.B.; Spergel, D.N.; Vilenkin, A.

    1986-01-01

    Superconducting loops of string formed in the early Universe, if they are relatively light, can be an important source of relativistic particles in the Galaxy. They can be observed as sources of synchrotron radiation at centimeter wavelengths. We propose a string model for two recently discovered radio sources, the ''thread'' in the galactic center and the source G357.7-0.1, and predict that the filaments in these sources should move at relativistic speeds. We also consider superheavy superconducting strings, and the possibility that they be observed as extragalactic radio sources

  13. Final Report: "Strings 2014"

    Energy Technology Data Exchange (ETDEWEB)

    Witten, Edward

    2015-10-21

    The Strings 2014 meeting was held at Princeton University June 23-27, 2014, co-sponsored by Princeton University and the Institute for Advanced Study. The goal of the meeting was to provide a stimulating and up-to-date overview of research in string theory and its relations to other areas of physics and mathematics, ranging from geometry to quantum field theory, condensed matter physics, and more. This brief report lists committee members and speakers but contains no scientific information. Note that the talks at Strings 2014 were videotaped and are available on the conference website: http://physics.princeton.edustrings2014/Talk_titles.shtml.

  14. A disintegrating cosmic string

    International Nuclear Information System (INIS)

    Griffiths, J B; Docherty, P

    2002-01-01

    We present a simple sandwich gravitational wave of the Robinson-Trautman family. This is interpreted as representing a shock wave with a spherical wavefront which propagates into a Minkowski background minus a wedge (i.e. the background contains a cosmic string). The deficit angle (the tension) of the string decreases through the gravitational wave, which then ceases. This leaves an expanding spherical region of Minkowski space behind it. The decay of the cosmic string over a finite interval of retarded time may be considered to generate the gravitational wave. (letter to the editor)

  15. Exceptional groups from open strings

    International Nuclear Information System (INIS)

    Gaberdiel, M.R.; Zwiebach, B.

    1998-01-01

    We consider type IIB theory compactified on a two-sphere in the presence of mutually non-local 7-branes. The BPS states associated with the gauge vectors of exceptional groups are seen to arise from open strings connecting the 7-branes, and multi-pronged open strings capable of ending on more than two 7-branes. These multi-pronged strings are built from open string junctions that arise naturally when strings cross 7-branes. The different string configurations can be multiplied as traditional open strings, and are shown to generate the structure of exceptional groups. (orig.)

  16. Space-time versus world-sheet renormalization group equation in string theory

    International Nuclear Information System (INIS)

    Brustein, R.; Roland, K.

    1991-05-01

    We discuss the relation between space-time renormalization group equation for closed string field theory and world-sheet renormalization group equation for first-quantized strings. Restricting our attention to massless states we argue that there is a one-to-one correspondence between the fixed point solutions of the two renormalization group equations. In particular, we show how to extract the Fischler-Susskind mechanism from the string field theory equation in the case of the bosonic string. (orig.)

  17. String propagation in an exact four-dimensional black hole background

    International Nuclear Information System (INIS)

    Mahapatra, S.

    1997-01-01

    We study string propagation in an exact, stringy, four-dimensional dyonic black hole background. The exact solutions in terms of elliptic functions describing string configurations in the J=0 limit are obtained by solving the string equations of motion and constraints. By using the covariant formalism, we also investigate the propagation of physical perturbations along the string in the given curved background. copyright 1997 The American Physical Society

  18. Enhanced gauge symmetry in type II string theory

    International Nuclear Information System (INIS)

    Katz, S.; Ronen Plesser, M.

    1996-01-01

    We show how enhanced gauge symmetry in type II string theory compactified on a Calabi-Yau threefold arises from singularities in the geometry of the target space. When the target space of the type IIA string acquires a genus g curve C of A N-1 singularities, we find that an SU(N) gauge theory with g adjoint hypermultiplets appears at the singularity. The new massless states correspond to solitons wrapped about the collapsing cycles, and their dynamics is described by a twisted supersymmetric gauge theory on C x R 4 . We reproduce this result from an analysis of the S-dual D-manifold. We check that the predictions made by this model about the nature of the Higgs branch, the monodromy of period integrals, and the asymptotics of the one-loop topological amplitude are in agreement with geometrical computations. In one of our examples we find that the singularity occurs at strong coupling in the heterotic dual proposed by Kachru and Vafa. (orig.)

  19. Constraints on modular inflation in supergravity and string theory

    International Nuclear Information System (INIS)

    Covi, L.; Palma, G.A.; Gomez-Reino, M.; Gross, C.; Louis, J.; Hamburg Univ.; Scrucca, C.A.

    2008-05-01

    We perform a general algebraic analysis on the possibility of realising slow-roll inflation in the moduli sector of string models. This problem turns out to be very closely related to the characterisation of models admitting metastable vacua with non-negative cosmological constant. In fact, we show that the condition for the existence of viable inflationary trajectories is a deformation of the condition for the existence of metastable de Sitter vacua. This condition depends on the ratio between the scale of inflation and the gravitino mass and becomes stronger as this parameter grows. After performing a general study within arbitrary supergravity models, we analyse the implications of our results in several examples. More concretely, in the case of heterotic and orientifold string compactifications on a Calabi-Yau in the large volume limit we show that there may exist fully viable models, allowing both for inflation and stabilisation. Additionally, we show that subleading corrections breaking the no-scale property shared by these models always allow for slow-roll inflation but with an inflationary scale suppressed with respect to the gravitino scale. A scale of inflation larger than the gravitino scale can also be achieved under more restrictive circumstances and only for certain types of compactifications. (orig.)

  20. Cosmic strings and cosmic structure

    International Nuclear Information System (INIS)

    Albrecht, A.; Brandenberger, R.; Turok, N.

    1987-01-01

    The paper concerns the application of the theory of cosmic strings to explain the structure of the Universe. The formation of cosmic strings in the early Universe is outlined, along with the Big Bang theory, Grand Unified theories, and the first three minutes after the Big Bang. A description is given of the shaping of the Universe by cosmic strings, including the evolution of the string. The possibility for direct observation of cosmic strings is discussed. (U.K.)

  1. International conference on string theory

    CERN Document Server

    2017-01-01

    The Strings 2017 conference is part of the "Strings" series of annual conferences, that bring the entire string theory community together. It will include reviews of major developments in the field, and specialized talks on specific topics. There will also be several public lectures given by conference participants, a pre-Strings school at the Technion, and a post-Strings workshop at the Weizmann Institute.

  2. String-math 2012

    CERN Document Server

    Katz, Sheldon; Klemm, Albrecht; Morrison, David R

    2015-01-01

    This volume contains the proceedings of the conference String-Math 2012, which was held July 16-21, 2012, at the Hausdorff Center for Mathematics, Universitat Bonn. This was the second in a series of annual large meetings devoted to the interface of mathematics and string theory. These meetings have rapidly become the flagship conferences in the field. Topics include super Riemann surfaces and their super moduli, generalized moonshine and K3 surfaces, the latest developments in supersymmetric and topological field theory, localization techniques, applications to knot theory, and many more. The contributors include many leaders in the field, such as Sergio Cecotti, Matthias Gaberdiel, Rahul Pandharipande, Albert Schwarz, Anne Taormina, Johannes Walcher, Katrin Wendland, and Edward Witten. This book will be essential reading for researchers and students in this area and for all mathematicians and string theorists who want to update themselves on developments in the math-string interface.

  3. Hydroball string sensing system

    International Nuclear Information System (INIS)

    Hurwitz, M.J.; Ekeroth, D.E.; Squarer, D.

    1991-01-01

    This patent describes a hydroball string sensing system for a nuclear reactor having a core containing a fluid at a fluid pressure. It comprises a tube connectable to the nuclear reactor so that the fluid can flow within the tube at a fluid pressure that is substantially the same as the fluid pressure of the nuclear reactor core; a hydroball string including - a string member having objects positioned therealong with a specified spacing, the object including a plurality of hydroballs, and bullet members positioned at opposing ends of the string member; first sensor means, positioned outside a first segment of the tube, for sensing one of the objects being positioned within the first segment, and for providing a sensing signal responsive to the sensing of the first sensing means

  4. The QCD Effective String

    International Nuclear Information System (INIS)

    Espriu, D.

    2003-01-01

    QCD can be described in a certain kinematical regime by an effective string theory. This string must couple to background chiral fields in a chirally invariant manner, thus taking into account the true chirally non-invariant QCD vacuum. By requiring conformal symmetry of the string and the unitarity constraint on chiral fields we reconstruct the equations of motion for the latter ones. These provide a consistent background for the propagation of the string. By further requiring locality of the effective action we recover the Lagrangian of non-linear sigma model of pion interactions. The prediction is unambiguous and parameter-free. The estimated chiral structural constants of Gasser and Leutwyler fit very well the phenomenological values. (author)

  5. Field theory of strings

    International Nuclear Information System (INIS)

    Ramond, P.

    1987-01-01

    We review the construction of the free equations of motion for open and closed strings in 26 dimensions, using the methods of the Florida Group. Differing from previous treatments, we argue that the constraint L 0 -anti L 0 =0 should not be imposed on all the fields of the closed string in the gauge invariant formalism; we show that it can be incorporated in the gauge invariant formalism at the price of being unable to extract the equations of motion from a Langrangian. We then describe our purely algebraic method to introduce interactions, which works equally well for open and closed strings. Quartic interactions are absent except in the Physical Gauge. Finally, we speculate on the role of the measure of the open string path functional. (orig.)

  6. String Theory Rocks!

    CERN Multimedia

    2008-01-01

    String Theory supporters argue that the universe we live in has eleven dimensions, out of which three spacial dimensions and a temporal one, which define the void and the space-time environment we experience daily.

  7. Voisin-Borcea manifolds and heterotic orbifold models

    Energy Technology Data Exchange (ETDEWEB)

    Buchmuller, W.; Schmidt, J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Louis, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Hamburg Univ. (Germany). Zentrum fuer Mathematische Physik; Valandro, R. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2012-08-15

    We study the relation between a heterotic T{sup 6}/Z{sub 6} orbifold model and a compactification on a smooth Voisin-Borcea Calabi-Yau three-fold with non-trivial line bundles. This orbifold can be seen as a Z{sub 2} quotient of T{sup 4}/Z{sub 3} x T{sup 2}. We consider a two-step resolution, whose intermediate step is (K3 x T{sup 2})/Z{sub 2}. This allows us to identify the massless twisted states which correspond to the geometric Kaehler and complex structure moduli. We work out the match of the two models when non-zero expectation values are given to all twisted geometric moduli. We find that even though the orbifold gauge group contains an SO(10) factor, a possible GUT group, the subgroup after Higgsing does not even include the standard model gauge group. Moreover, after Higgsing, the massless spectrum is non-chiral under the surviving gauge group.

  8. Lectures on string theory

    International Nuclear Information System (INIS)

    Thorn, C.B.

    1988-01-01

    Several topics are discussed in string theory presented as three lectures to the Spring School on Superstrings at the ICTP at Trieste, Italy, in April, 1988. The first lecture is devoted to some general aspects of conformal invariance and duality. The second sketches methods for carrying out perturbative calculations in string field theory. The final lecture presents an alternative lattice approach to a nonperturbative formulation of the sum over world surfaces. 35 refs., 12 figs

  9. String dynamics in QCD

    International Nuclear Information System (INIS)

    Gervais, J.L.; Neveu, A.

    1980-01-01

    Recent works of the authors on string interpretation of the Wilson loop operators in QCD are reviewed in a self-contained fashion. Although most of the results habe already appeared in print, some new material is presented in renormalization of the Wilson loop operator and on the use of light-cone expansion to derive a linear string-like equation in light-cone formalism. (orig.)

  10. Matrix String Theory

    CERN Document Server

    Dijkgraaf, R; Verlinde, Herman L

    1997-01-01

    Via compactification on a circle, the matrix model of M-theory proposed by Banks et al suggests a concrete identification between the large N limit of two-dimensional N=8 supersymmetric Yang-Mills theory and type IIA string theory. In this paper we collect evidence that supports this identification. We explicitly identify the perturbative string states and their interactions, and describe the appearance of D-particle and D-membrane states.

  11. Manipulating Strings in Python

    Directory of Open Access Journals (Sweden)

    William J. Turkel

    2012-07-01

    Full Text Available This lesson is a brief introduction to string manipulation techniques in Python. Knowing how to manipulate strings plays a crucial role in most text processing tasks. If you’d like to experiment with the following lessons, you can write and execute short programs as we’ve been doing, or you can open up a Python shell / Terminal to try them out on the command line.

  12. Strings - Links between conformal field theory, gauge theory and gravity

    International Nuclear Information System (INIS)

    Troost, J.

    2009-05-01

    String theory is a candidate framework for unifying the gauge theories of interacting elementary particles with a quantum theory of gravity. The last years we have made considerable progress in understanding non-perturbative aspects of string theory, and in bringing string theory closer to experiment, via the search for the Standard Model within string theory, but also via phenomenological models inspired by the physics of strings. Despite these advances, many deep problems remain, amongst which a non-perturbative definition of string theory, a better understanding of holography, and the cosmological constant problem. My research has concentrated on various theoretical aspects of quantum theories of gravity, including holography, black holes physics and cosmology. In this Habilitation thesis I have laid bare many more links between conformal field theory, gauge theory and gravity. Most contributions were motivated by string theory, like the analysis of supersymmetry preserving states in compactified gauge theories and their relation to affine algebras, time-dependent aspects of the holographic map between quantum gravity in anti-de-Sitter space and conformal field theories in the bulk, the direct quantization of strings on black hole backgrounds, the embedding of the no-boundary proposal for a wave-function of the universe in string theory, a non-rational Verlinde formula and the construction of non-geometric solutions to supergravity

  13. Stationary strings near a higher-dimensional rotating black hole

    International Nuclear Information System (INIS)

    Frolov, Valeri P.; Stevens, Kory A.

    2004-01-01

    We study stationary string configurations in a space-time of a higher-dimensional rotating black hole. We demonstrate that the Nambu-Goto equations for a stationary string in the 5D (five-dimensional) Myers-Perry metric allow a separation of variables. We present these equations in the first-order form and study their properties. We prove that the only stationary string configuration that crosses the infinite redshift surface and remains regular there is a principal Killing string. A worldsheet of such a string is generated by a principal null geodesic and a timelike at infinity Killing vector field. We obtain principal Killing string solutions in the Myers-Perry metrics with an arbitrary number of dimensions. It is shown that due to the interaction of a string with a rotating black hole, there is an angular momentum transfer from the black hole to the string. We calculate the rate of this transfer in a space-time with an arbitrary number of dimensions. This effect slows down the rotation of the black hole. We discuss possible final stationary configurations of a rotating black hole interacting with a string

  14. On the Rotating and Oscillating strings in $(AdS_3\\times S^3)_{\\varkappa}$

    CERN Document Server

    Banerjee, Aritra

    2014-01-01

    We study rigidly rotating strings in the $\\varkappa$-deformed $AdS_3 \\times S^3$ background. We find out two classes of solutions corresponding to the giant magnon and single spike solutions of the string rotating is two $S^2_{\\varkappa}$ subspace of rotations reduced along two different isometries. We verify that the dispersion relations reduce to the well known relation in the $\\varkappa\\rightarrow 0$ limit. We further study some oscillating string solutions in the $S^3_{\\varkappa}$ subspace.

  15. Purely cubic action for string field theory

    Science.gov (United States)

    Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

    1986-01-01

    It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.

  16. Algebraic structure of open string interactions

    International Nuclear Information System (INIS)

    Ramond, P.; Rodgers, V.G.J.

    1986-05-01

    Starting from the gauge invariant equations of motion for the free open string we show how to generate interactions by analogy with Yang-Mills. We postulate Non-Abelian transformation laws acting on the fields of the gauge invariant free open string theory. By demanding algebraic closure we then derive a set of consistency requirements and show that they lead to the construction of the minimal interacting equations which contain no cubic terms away from the physical gauge. We present explicit solutions to lowest interacting order for both vertices and structure functions. 14 refs

  17. Algebraic structure of open-string interactions

    International Nuclear Information System (INIS)

    Ramond, P.; Rodgers, V.G.J.

    1986-01-01

    Starting from the gauge-invariant equations of motion for the free open string we show how to generate interactions by analogy with the Yang-Mills system. We postulate non-Abelian transformation laws acting on the fields of the gauge-invariant free open-string theory. By demanding algebraic closure we then derive a set of consistency requirements and show that they lead to the construction of the minimal interacting equations which contain no cubic terms away from the physical gauge. We present explicit solutions to lowest interacting order for both vertices and structure functions

  18. Exactly solvable string models of curved space-time backgrounds

    CERN Document Server

    Russo, J.G.; Russo, J G; Tseytlin, A A

    1995-01-01

    We consider a new 3-parameter class of exact 4-dimensional solutions in closed string theory and solve the corresponding string model, determining the physical spectrum and the partition function. The background fields (4-metric, antisymmetric tensor, two Kaluza-Klein vector fields, dilaton and modulus) generically describe axially symmetric stationary rotating (electro)magnetic flux-tube type universes. Backgrounds of this class include both the dilatonic Melvin solution and the uniform magnetic field solution discussed earlier as well as some singular space-times. Solvability of the string sigma model is related to its connection via duality to a much simpler looking model which is a "twisted" product of a flat 2-space and a space dual to 2-plane. We discuss some physical properties of this model as well as a number of generalizations leading to larger classes of exact 4-dimensional string solutions.

  19. Origin of Abelian gauge symmetries in heterotic/F-theory duality

    International Nuclear Information System (INIS)

    Cvetič, Mirjam; Grassi, Antonella; Klevers, Denis; Poretschkin, Maximilian; Song, Peng

    2016-01-01

    We study aspects of heterotic/F-theory duality for compactifications with Abelian gauge symmetries. We consider F-theory on general Calabi-Yau manifolds with a rank one Mordell-Weil group of rational sections. By rigorously performing the stable degeneration limit in a class of toric models, we derive both the Calabi-Yau geometry as well as the spectral cover describing the vector bundle in the heterotic dual theory. We carefully investigate the spectral cover employing the group law on the elliptic curve in the heterotic theory. We find in explicit examples that there are three different classes of heterotic duals that have U(1) factors in their low energy effective theories: split spectral covers describing bundles with S(U(m)×U(1)) structure group, spectral covers containing torsional sections that seem to give rise to bundles with SU(m)×ℤ_k structure group and bundles with purely non-Abelian structure groups having a centralizer in E_8 containing a U(1) factor. In the former two cases, it is required that the elliptic fibration on the heterotic side has a non-trivial Mordell-Weil group. While the number of geometrically massless U(1)’s is determined entirely by geometry on the F-theory side, on the heterotic side the correct number of U(1)’s is found by taking into account a Stückelberg mechanism in the lower-dimensional effective theory. In geometry, this corresponds to the condition that sections in the two half K3 surfaces that arise in the stable degeneration limit of F-theory can be glued together globally.

  20. Duality symmetries and the Type II string effective action

    International Nuclear Information System (INIS)

    Bergshoeff, E.

    1996-01-01

    We discuss the duality symmetries of Type II string effective actions in nine, ten and eleven dimensions. As a by-product we give a covariant action underlying the ten-dimensional Type IIB supergravity theory. We apply duality symmetries to construct dyonic Type II string solutions in six dimensions and their reformulation as solutions of the ten-dimensional Type IIB theory in ten dimensions. (orig.)

  1. Open-string models with broken supersymmetry

    International Nuclear Information System (INIS)

    Sagnotti, A.

    2002-01-01

    I review the salient features of three classes of open-string models with broken supersymmetry. These suffice to exhibit, in relatively simple settings, the two phenomena of 'brane supersymmetry' and 'brane supersymmetry breaking'. In the first class of models, to lowest order supersymmetry is broken both in the closed and in the open sectors. In the second class of models, to lowest order supersymmetry is broken in the closed sector, but is exact in the open sector, at least for the low-lying modes, and often for entire towers of string excitations. Finally, in the third class of models, to lowest order supersymmetry is exact in the closed (bulk) sector, but is broken in the open sector. Brane supersymmetry breaking provides a natural solution to some old difficulties met in the construction of open-string vacua. (author)

  2. Open-string models with broken supersymmetry

    International Nuclear Information System (INIS)

    Sagnotti, Augusto

    2000-01-01

    We review the salient features of three classes of open-string models with broken supersymmetry. These suffice to exhibit, in relatively simple settings, the two phenomena of 'brane supersymmetry' and 'brane supersymmetry breaking'. In the first class of models, to lowest order supersymmetry is broken both in the closed and in the open sectors. In the second class of models, to lowest order supersymmetry is broken in the closed sector, but is exact in the open sector, at least for the low-lying modes, and often for entire towers of string excitations. Finally, in the third class of models, to lowest order supersymmetry is exact in the closed (bulk) sector, but is broken in the open sector. Brane supersymmetry breaking provides a natural solution to some old difficulties met in the construction of open-string vacua

  3. The effective supergravity of little string theory

    Science.gov (United States)

    Antoniadis, Ignatios; Delgado, Antonio; Markou, Chrysoula; Pokorski, Stefan

    2018-02-01

    In this work we present the minimal supersymmetric extension of the five-dimensional dilaton-gravity theory that captures the main properties of the holographic dual of little string theory. It is described by a particular gauging of N=2 supergravity coupled with one vector multiplet associated with the string dilaton, along the U(1) subgroup of SU(2) R-symmetry. The linear dilaton in the fifth coordinate solution of the equations of motion (with flat string frame metric) breaks half of the supersymmetries to N=1 in four dimensions. Interest in the linear dilaton model has lately been revived in the context of the clockwork mechanism, which has recently been proposed as a new source of exponential scale separation in field theory.

  4. The effective supergravity of little string theory

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, Ignatios [Sorbonne Universite, CNRS, Laboratoire de Physique Theorique et Hautes Energies, LPTHE, Paris (France); University of Bern, Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, Bern (Switzerland); Delgado, Antonio [University of Notre Dame, Department of Physics, Notre Dame, IN (United States); Markou, Chrysoula [Sorbonne Universite, CNRS, Laboratoire de Physique Theorique et Hautes Energies, LPTHE, Paris (France); Pokorski, Stefan [University of Warsaw, Faculty of Physics, Institute of Theoretical Physics, Warsaw (Poland)

    2018-02-15

    In this work we present the minimal supersymmetric extension of the five-dimensional dilaton-gravity theory that captures the main properties of the holographic dual of little string theory. It is described by a particular gauging of N = 2 supergravity coupled with one vector multiplet associated with the string dilaton, along the U(1) subgroup of SU(2) R-symmetry. The linear dilaton in the fifth coordinate solution of the equations of motion (with flat string frame metric) breaks half of the supersymmetries to N = 1 in four dimensions. Interest in the linear dilaton model has lately been revived in the context of the clockwork mechanism, which has recently been proposed as a new source of exponential scale separation in field theory. (orig.)

  5. Small scale structure on cosmic strings

    International Nuclear Information System (INIS)

    Albrecht, A.

    1989-01-01

    I discuss our current understanding of cosmic string evolution, and focus on the question of small scale structure on strings, where most of the disagreements lie. I present a physical picture designed to put the role of the small scale structure into more intuitive terms. In this picture one can see how the small scale structure can feed back in a major way on the overall scaling solution. I also argue that it is easy for small scale numerical errors to feed back in just such a way. The intuitive discussion presented here may form the basis for an analytic treatment of the small structure, which I argue in any case would be extremely valuable in filling the gaps in our resent understanding of cosmic string evolution. 24 refs., 8 figs

  6. Low-energy supergravities from heterotic compactification on reduced structure backgrounds

    International Nuclear Information System (INIS)

    Martinez Pedrera, Danny Manuel

    2009-10-01

    In this thesis, the compactification of heterotic supergravity on six-dimensional manifolds with SU(2) and SU(3) structure is studied. For the SU(2)-structure backgrounds, the spectrum and the bosonic action of the effective theory in four dimensions are obtained. The results are gauged versions of the ungauged N=2 supergravity obtained after compactification on K3 x T 2 . The gauge algebra and the Killing prepotentials are also computed. For the SU(3)-structure backgrounds, the couplings of the resulting N=1 supergravity are computed by reducing terms on the heterotic supergravity action involving fermionic fields, and are further checked by computing the supersymmetry variations of the fermions. (orig.)

  7. Use of induced chlorophyll deficient mutants to identify 'heterotic blocks' in pearl millet chromosomes

    International Nuclear Information System (INIS)

    Burton, G.W.

    1989-01-01

    Full text: Chlorophyll deficient mutant stocks induced in 'Tift 23' of pearl millet (Pennisetum americanum L. Leeke) were crossed with 'Tift 23' and 5 other normal inbreds to study the effect of these deleterious recessive genes on yield. The difference between near-isogenic S 1 (F 2 ) populations homozygous or heterozygous for the chlorophyll deficiency was not significant. However among 69 S 1 progenies from crosses with other inbreds the heterozygotes were higher yielding than the homozygotes in 53 cases, 15 of which were significant. A mutant like 'M5' identified a high yield 'heterotic block' in 'Inbred 104' and a very low yield 'heterotic block' in 'Inbred 186'. (author)

  8. Proceedings of the 14. Claude Itzykson Meeting-2009 recent advances in string theory

    International Nuclear Information System (INIS)

    Aharoni, O.; Arkani-Hamed, N.; Becker, K.; Berkovits, N.; Bern, Z.; De Boer, J.; Emparan, R.; Green, M.; Hartnoll, S.; Heckman, J.; Kachru, S.; Lambert, N.; Louis, J.; Marino, M.; Mathur, S.; McAllister, L.; McGreevy, J.; Polchinski, J.; Sen, A.; Weigand, T.

    2009-01-01

    This document is made up of the slides of the presentations. The titles of the 20 presentations are the following: 1) On d=3 Yang-Mills Chern-Simons theories with 'fractional branes' and their gravity duals; 2) Holography and the S-Matrix; 3) Torsional heterotic geometries; 4) Spin chains from the topological AdS 5 xS 5 string; 5) Harmony of Scattering Amplitudes: from N=4 Super-Yang-Mills Theory to N=8 Supergravity; 6) Quantum aspects of black holes; 7) Black-folds; 8) Supersymmetric String and Field Theory Scattering Amplitudes; 9) Quantum bosons for holographic superconductors; 10) The Point of E8 in F-theory GUTs; 11) Gauge/gravity duality and particle physics; 12) Coupling M2-branes to Background Fields; 13) Compactifications and Generalized Geometries; 14) Nonperturbative aspects of the topological string; 15) Lessons from the information paradox: 16) Inflation in String Theory; 17) Holographic descriptions of quantum liquids; 18) Holography from CFT; 19) Black hole hair removal; and 20) Type IIB GUT vacua and their F-theory uplift

  9. Solution Structure of the Tandem Acyl Carrier Protein Domains from a Polyunsaturated Fatty Acid Synthase Reveals Beads-on-a-String Configuration

    KAUST Repository

    Trujillo, Uldaeliz

    2013-02-28

    The polyunsaturated fatty acid (PUFA) synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP) domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect) and in structural stabilization of the multidomain protein (synergistic effect). While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS) revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of multiple ACP

  10. Solution Structure of the Tandem Acyl Carrier Protein Domains from a Polyunsaturated Fatty Acid Synthase Reveals Beads-on-a-String Configuration

    KAUST Repository

    Trujillo, Uldaeliz; Vá zquez-Rosa, Edwin; Oyola-Robles, Delise; Stagg, Loren J.; Vassallo, David A.; Vega, Irving E.; Arold, Stefan T.; Baerga-Ortiz, Abel

    2013-01-01

    The polyunsaturated fatty acid (PUFA) synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP) domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect) and in structural stabilization of the multidomain protein (synergistic effect). While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS) revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of multiple ACP

  11. Solution structure of the tandem acyl carrier protein domains from a polyunsaturated fatty acid synthase reveals beads-on-a-string configuration.

    Directory of Open Access Journals (Sweden)

    Uldaeliz Trujillo

    Full Text Available The polyunsaturated fatty acid (PUFA synthases from deep-sea bacteria invariably contain multiple acyl carrier protein (ACP domains in tandem. This conserved tandem arrangement has been implicated in both amplification of fatty acid production (additive effect and in structural stabilization of the multidomain protein (synergistic effect. While the more accepted model is one in which domains act independently, recent reports suggest that ACP domains may form higher oligomers. Elucidating the three-dimensional structure of tandem arrangements may therefore give important insights into the functional relevance of these structures, and hence guide bioengineering strategies. In an effort to elucidate the three-dimensional structure of tandem repeats from deep-sea anaerobic bacteria, we have expressed and purified a fragment consisting of five tandem ACP domains from the PUFA synthase from Photobacterium profundum. Analysis of the tandem ACP fragment by analytical gel filtration chromatography showed a retention time suggestive of a multimeric protein. However, small angle X-ray scattering (SAXS revealed that the multi-ACP fragment is an elongated monomer which does not form a globular unit. Stokes radii calculated from atomic monomeric SAXS models were comparable to those measured by analytical gel filtration chromatography, showing that in the gel filtration experiment, the molecular weight was overestimated due to the elongated protein shape. Thermal denaturation monitored by circular dichroism showed that unfolding of the tandem construct was not cooperative, and that the tandem arrangement did not stabilize the protein. Taken together, these data are consistent with an elongated beads-on-a-string arrangement of the tandem ACP domains in PUFA synthases, and speak against synergistic biocatalytic effects promoted by quaternary structuring. Thus, it is possible to envision bioengineering strategies which simply involve the artificial linking of

  12. Deterministic indexing for packed strings

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Skjoldjensen, Frederik Rye

    2017-01-01

    Given a string S of length n, the classic string indexing problem is to preprocess S into a compact data structure that supports efficient subsequent pattern queries. In the deterministic variant the goal is to solve the string indexing problem without any randomization (at preprocessing time...... or query time). In the packed variant the strings are stored with several character in a single word, giving us the opportunity to read multiple characters simultaneously. Our main result is a new string index in the deterministic and packed setting. Given a packed string S of length n over an alphabet σ...

  13. Integrated hydraulic booster/tool string technology for unfreezing of stuck downhole strings in horizontal wells

    Science.gov (United States)

    Tian, Q. Z.

    2017-12-01

    It is common to use a jarring tool to unfreeze stuck downhole string. However, in a horizontal well, influenced by the friction caused by the deviated section, jarring effect is poor; on the other hand, the forcing point can be located in the horizontal section by a hydraulic booster and the friction can be reduced, but it is time-consuming and easy to break downhole string using a large-tonnage and constant pull force. A hydraulic booster - jar tool string has been developed for unfreezing operation in horizontal wells. The technical solution involves three elements: a two-stage parallel spring cylinder structure for increasing the energy storage capacity of spring accelerators; multiple groups of spring accelerators connected in series to increase the working stroke; a hydraulic booster intensifying jarring force. The integrated unfreezing tool string based on these three elements can effectively overcome the friction caused by a deviated borehole, and thus unfreeze a stuck string with the interaction of the hydraulic booster and the mechanical jar which form an alternatively dynamic load. Experimental results show that the jarring performance parameters of the hydraulic booster-jar unfreezing tool string for the horizontal wells are in accordance with original design requirements. Then field technical parameters were developed based on numerical simulation and experimental data. Field application shows that the hydraulic booster-jar unfreezing tool string is effective to free stuck downhole tools in a horizontal well, and it reduces hook load by 80% and lessens the requirement of workover equipment. This provides a new technology to unfreeze stuck downhole string in a horizontal well.

  14. Windings of twisted strings

    Science.gov (United States)

    Casali, Eduardo; Tourkine, Piotr

    2018-03-01

    Twistor string models have been known for more than a decade now but have come back under the spotlight recently with the advent of the scattering equation formalism which has greatly generalized the scope of these models. A striking ubiquitous feature of these models has always been that, contrary to usual string theory, they do not admit vibrational modes and thus describe only conventional field theory. In this paper we report on the surprising discovery of a whole new sector of one of these theories which we call "twisted strings," when spacetime has compact directions. We find that the spectrum is enhanced from a finite number of states to an infinite number of interacting higher spin massive states. We describe both bosonic and world sheet supersymmetric models, their spectra and scattering amplitudes. These models have distinctive features of both string and field theory, for example they are invariant under stringy T-duality but have the high energy behavior typical of field theory. Therefore they describe a new kind of field theories in target space, sitting on their own halfway between string and field theory.

  15. Strings and fundamental physics

    International Nuclear Information System (INIS)

    Baumgartl, Marco; Brunner, Ilka; Haack, Michael

    2012-01-01

    The basic idea, simple and revolutionary at the same time, to replace the concept of a point particle with a one-dimensional string, has opened up a whole new field of research. Even today, four decades later, its multifaceted consequences are still not fully conceivable. Up to now string theory has offered a new way to view particles as different excitations of the same fundamental object. It has celebrated success in discovering the graviton in its spectrum, and it has naturally led scientists to posit space-times with more than four dimensions - which in turn has triggered numerous interesting developments in fields as varied as condensed matter physics and pure mathematics. This book collects pedagogical lectures by leading experts in string theory, introducing the non-specialist reader to some of the newest developments in the field. The carefully selected topics are at the cutting edge of research in string theory and include new developments in topological strings, AdS/CFT dualities, as well as newly emerging subfields such as doubled field theory and holography in the hydrodynamic regime. The contributions to this book have been selected and arranged in such a way as to form a self-contained, graduate level textbook. (orig.)

  16. Strings and fundamental physics

    Energy Technology Data Exchange (ETDEWEB)

    Baumgartl, Marco [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Brunner, Ilka; Haack, Michael (eds.) [Muenchen Univ. (Germany). Fakultaet fuer Physik

    2012-07-01

    The basic idea, simple and revolutionary at the same time, to replace the concept of a point particle with a one-dimensional string, has opened up a whole new field of research. Even today, four decades later, its multifaceted consequences are still not fully conceivable. Up to now string theory has offered a new way to view particles as different excitations of the same fundamental object. It has celebrated success in discovering the graviton in its spectrum, and it has naturally led scientists to posit space-times with more than four dimensions - which in turn has triggered numerous interesting developments in fields as varied as condensed matter physics and pure mathematics. This book collects pedagogical lectures by leading experts in string theory, introducing the non-specialist reader to some of the newest developments in the field. The carefully selected topics are at the cutting edge of research in string theory and include new developments in topological strings, AdS/CFT dualities, as well as newly emerging subfields such as doubled field theory and holography in the hydrodynamic regime. The contributions to this book have been selected and arranged in such a way as to form a self-contained, graduate level textbook. (orig.)

  17. String-Corrected Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Hubeny, V.

    2005-01-12

    We investigate the geometry of four dimensional black hole solutions in the presence of stringy higher curvature corrections to the low energy effective action. For certain supersymmetric two charge black holes these corrections drastically alter the causal structure of the solution, converting seemingly pathological null singularities into timelike singularities hidden behind a finite area horizon. We establish, analytically and numerically, that the string-corrected two-charge black hole metric has the same Penrose diagram as the extremal four-charge black hole. The higher derivative terms lead to another dramatic effect--the gravitational force exerted by a black hole on an inertial observer is no longer purely attractive. The magnitude of this effect is related to the size of the compactification manifold.

  18. On the geometrical approach to the relativistic string theory

    International Nuclear Information System (INIS)

    Barbashov, B.M.; Nesterenko, V.V.

    1978-01-01

    In a geometrical approach to the string theory in the four-dimensional Minkowski space the relativistic invariant gauge proposed earlier for the string moving in three-dimensional space-time is used. In contrast to the results of previous paper the system of equations for the coefficients of the fundamental forms of the string model world sheet can be reduced now to one nonlinear Lionville equation again but for a complex valued function u. It is shown that in the case of space-time with arbitrary dimension there are such string motions which are described by one non-linear equation with a real function u. And as a consequence the soliton solutions investigated earlier take place in a geometrical approach to the string theory in any dimensional space-time

  19. Quantum and classical aspects of deformed c = 1 strings

    International Nuclear Information System (INIS)

    Nakatsu, T.; Tsujimaru, S.; Takasaki, K.

    1995-01-01

    The quantum and classical aspects of a deformed c=1 matrix model proposed by Jevicki and Yoneya are studied. String equations are formulated in the framework of the Toda lattice hierarchy. The Whittaker functions now play the role of generalized Airy functions in c<1 strings. This matrix model has two distinct parameters. Identification of the string coupling constant is thereby not unique, and leads to several different perturbative interpretations of this model as a string theory. Two such possible interpretations are examined. In both cases, the classical limit of the string equations, which turns out to give a formal solution of Polchinski's scattering equations, shows that the classical scattering amplitudes of massless tachyons are insensitive to deformations of the parameters in the matrix model. (author)

  20. Coulomb string tension, asymptotic string tension, and the gluon chain

    OpenAIRE

    Greensite, Jeff; Szczepaniak, Adam P.

    2014-01-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  1. Interacting-string picture of the fermionic string

    International Nuclear Information System (INIS)

    Mandelstam, S.

    1986-01-01

    This report gives a review of the interacting-string picture of the Bose string. In the present lecture, the author outlines a similar treatment of the Fermionic string. The quantization of the free Fermionic string is carried out to the degrees of freedom x, representing the displacement of the string. Also presented are Grassman degrees of freedom S distributed along the string. The report pictures the fermionic string as a string of dipoles. The general picture of the interaction of such strings by joining and splitting is the same as for the Bose string. The author does not at present have the simplest formula for fermion string scattering amplitudes. A less detailed treatment is given than for the Bose string. The report sets up the functional-integration formalism, derives the analog mode, and indicates in general, terms how the conformal transformation to the z-plane may be performed. The paper concludes by stating without proof the formula for the N-article tree amplitude in the manifestly supersymmetric formalism

  2. Are Stopped Strings Preferred in Sad Music?

    OpenAIRE

    David Huron; Caitlyn Trevor

    2017-01-01

    String instruments may be played either with open strings (where the string vibrates between the bridge and a hard wooden nut) or with stopped strings (where the string vibrates between the bridge and a performer's finger pressed against the fingerboard). Compared with open strings, stopped strings permit the use of vibrato and exhibit a darker timbre. Inspired by research on the timbre of sad speech, we test whether there is a tendency to use stopped strings in nominally sad music. Specifica...

  3. Strings for quantumchromodynamics

    International Nuclear Information System (INIS)

    Schomerus, V.

    2007-04-01

    During the last decade, intriguing dualities between gauge and string theory have been found and explored. they provide a novel window on strongly couplde gauge physics, including QCD-like models. Based on a short historical review of modern string theory, we explain how so-called AdS/CFT dualities emerged at the end of the 1990s. Some of their concrete implications and remarkable recent progress are then illustrated for the simplest example, namely the multicolor limit of N=4 SYM theory in four dimensions. We end with a few comments on existing extensions to more realistic models and applications, in particular to the sQGP. This text is meant as a non-technical introduction to gauge/string dualities for (particle) physicists. (orig.)

  4. Strings for quantumchromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Schomerus, V.

    2007-04-15

    During the last decade, intriguing dualities between gauge and string theory have been found and explored. they provide a novel window on strongly couplde gauge physics, including QCD-like models. Based on a short historical review of modern string theory, we explain how so-called AdS/CFT dualities emerged at the end of the 1990s. Some of their concrete implications and remarkable recent progress are then illustrated for the simplest example, namely the multicolor limit of N=4 SYM theory in four dimensions. We end with a few comments on existing extensions to more realistic models and applications, in particular to the sQGP. This text is meant as a non-technical introduction to gauge/string dualities for (particle) physicists. (orig.)

  5. Quark potential of spontaneous strings

    International Nuclear Information System (INIS)

    German, G.; Kleinert, H.

    1989-01-01

    The authors present some recent developments in string models with an extrinsic curvature term in action. Particular emphasis is placed upon the static quark potential and on the thermal deconfinement properties of spontaneous strings

  6. Cosmic strings and galaxy formation

    International Nuclear Information System (INIS)

    Bertschinger, E.

    1989-01-01

    Cosmic strings have become increasingly popular candidates as seeds for the formation of structure in the universe. This scenario, remains a serious cosmogonical model despite close scrutiny. In constrast, magnetic monopoles and domain walls - relic topological defects as are cosmic strings - are disastrous for cosmology if they are left over from the early universe. The production of heavy cosmic strings is speculative, as it depends on the details of ultrahigh energy physics. Fortunately, speculation about cosmic strings is not entirely idle because, if they exist and are heavy enough to seed galaxy formation, cosmic strings can be detected astronomically. Failure to detect cosmic strings would impose some constraints on grand unified theories (GUTs); their discovery would have exciting consequences for high energy physics and cosmology. This article reviews the basic physics of nonsuperconducting cosmic strings, highlighting the field theory aspects, and provides a progress report on calculations of structure formation with cosmic strings

  7. STRING v10

    DEFF Research Database (Denmark)

    Szklarczyk, Damian; Franceschini, Andrea; Wyder, Stefan

    2015-01-01

    , and the available data exhibit notable differences in terms of quality and completeness. The STRING database (http://string-db.org) aims to provide a critical assessment and integration of protein-protein interactions, including direct (physical) as well as indirect (functional) associations. The new version 10...... into families at various levels of phylogenetic resolution. Further improvements in version 10.0 include a completely redesigned prediction pipeline for inferring protein-protein associations from co-expression data, an API interface for the R computing environment and improved statistical analysis...

  8. Proceedings of strings, 89

    International Nuclear Information System (INIS)

    Arnowitt, R.; Bryan, R.; Duff, M.J.; Nanopoulos, D.; Pope, C.N.

    1990-01-01

    Does string theory provide us with a consistent quantum theory of gravity? Is it that Holy Grail of elementary particle physics, a Theory of Everything with embraces all the forces and particles of Nature? Even if it is, can we extract concrete predictions about our low-energy world that can be tested experimentally at the SSC and other particle accelerators? What does it have to say about the origin of the Universe and the thorny problem of the cosmological constant? Are superstring theories unique, or might the eleven-dimensional supermembrane prove equally consistent? These are just some of the question posed and debated at Strings '89

  9. Strings draw theorists together

    International Nuclear Information System (INIS)

    Green, Michael

    2000-01-01

    Theorists are confident that they are closer than ever to finding a quantum theory that unites gravity with the three other fundamental forces in nature. Many of the leading figures in the world of string theory met at the California Institute of Technology in January to discuss recent progress in the field and to reflect on the state of the theory. The enthusiastic mood of the gathering was based on the fact that string theory provides an elegant framework for a unified theory of all the forces and particles in nature, and also gives a consistent quantum-mechanical description of general relativity. String theory, and more precisely superstring theory, describes the assortment of elementary particles such as quarks and leptons, and the gauge bosons responsible for mediating forces in a unified manner as different modes of vibration of a single extended string. This version of the theory also embodies supersymmetry a conjectured symmetry that unifies fermions and bosons. Furthermore, the fact that the string has a fundamental length scale - the ''string length'' - apparently cures the short-distance problems of uniting general relativity with quantum theory. The main problem with the early formulations of superstring theory was that they emphasized the ''perturbative'' point of view, an approximation that describes string-like quantum-mechanical particles moving through classical (that is non quantum-mechanical) space-time. However, very general arguments require that any quantum theory of gravity should also describe space-time geometry in a quantum-mechanical manner. The classical geometry of space-time should then emerge as an approximate description at distance scales much larger than the so-called Planck scale of 10 -33 m. This requires an understanding of the theory beyond the perturbative approximation. It is the quest for this more fundamental description of string theory that has provided the main challenge for string theorists over the past decade. Much

  10. Introduction to string theory

    International Nuclear Information System (INIS)

    Randjbar-Daemi, S.; Strathdee, J.

    1987-10-01

    These notes are based on a set of six introductory lectures given jointly by the authors. After developing the canonical methods we discuss the covariant quantization of the bosonic as well as the fermionic string. Conformal field theory methods are also introduced and used to calculate the anomaly coefficient, c, as well as the critical dimensions for bosonic and superstrings. We briefly sketch the BRS quantization and then offer an elementary derivation of the anomaly in the ghost number current. Finally, we address the one-loop partition function of the bosonic string and the question of SL(2,Z) invariance. (author). 15 refs

  11. Matrix string partition function

    CERN Document Server

    Kostov, Ivan K; Kostov, Ivan K.; Vanhove, Pierre

    1998-01-01

    We evaluate quasiclassically the Ramond partition function of Euclidean D=10 U(N) super Yang-Mills theory reduced to a two-dimensional torus. The result can be interpreted in terms of free strings wrapping the space-time torus, as expected from the point of view of Matrix string theory. We demonstrate that, when extrapolated to the ultraviolet limit (small area of the torus), the quasiclassical expressions reproduce exactly the recently obtained expression for the partition of the completely reduced SYM theory, including the overall numerical factor. This is an evidence that our quasiclassical calculation might be exact.

  12. The energy and stability of D-term strings

    International Nuclear Information System (INIS)

    Collinucci, Andres; Smyth, Paul; Proeyen, Antoine van

    2007-01-01

    Cosmic strings derived from string theory, supergravity or any theory of choice should be stable if we hope to observe them. In this paper we consider D-term strings in D = 4 , N = 1 supergravity with a constant Fayet-Iliopoulos term. We show that the positive deficit angle supersymmetric D-term string is non-perturbatively stable by using standard Witten-Nester techniques to prove a positive energy theorem. Particular attention is paid to the negative deficit angle D-term string, which is known to violate the dominant energy condition. Within the class of string solutions we consider, this violation implies that the negative deficit angle D-term string must have a naked pathology and therefore the positive energy theorem we prove does not apply to it. As an interesting aside, we show that the Witten-Nester charge calculates the total gravitational energy of the D-term string without the need for a cut-off, which may not have been expected

  13. Deriving the four-string and open-closed string interactions from geometric string field theory

    International Nuclear Information System (INIS)

    Kaku, M.

    1990-01-01

    One of the questions concerning the covariant open string field theory is why there are two distinct BRST theories and why the four-string interaction appears in one version but not the other. The authors solve this mystery by showing that both theories are gauge-fixed versions of a higher gauge theory, called the geometric string field theory, with a new field, a string verbein e μσ νρ , which allows us to gauge the string length and σ parametrization. By fixing the gauge, the authors can derive the endpoint gauge (the covariantized light cone gauge), the midpoint gauge of Witten, or the interpolating gauge with arbitrary string length. The authors show explicitly that the four-string interaction is a gauge artifact of the geometric theory (the counterpart of the four-fermion instantaneous Coulomb term of QED). By choosing the interpolating gauge, they produce a new class of four-string interactions which smoothly interpolate between the endpoint gauge and the midpoint gauge (where it vanishes). Similarly, they can extract the closed string as a bound state of the open string, which appears in the endpoint gauge but vanishes in the midpoint gauge. Thus, the four-string and open-closed string interactions do not have to be added to the action as long as the string vierbein is included

  14. Racetrack inflation and cosmic strings

    Energy Technology Data Exchange (ETDEWEB)

    Brax, P. [CEA-Saclay, Gif sur Yvette (France). CEA/DSM/SPhT, Unite de Recherche Associee au CNRS, Service de Physique Theorique; Bruck, C. van de [Sheffield Univ. (United Kingdom). Dept. of Applied Mathematics; Davis, A.C.; Davis, S.C. [Cambridge Univ. (United Kingdom). DAMTP, Centre for Mathematical Sciences; Jeannerot, R. [Instituut-Lorentz for Theoretical Physics, Leiden (Netherlands); Postma, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands)

    2008-05-15

    We consider the coupling of racetrack inflation to matter fields as realised in the D3/D7 brane system. In particular, we investigate the possibility of cosmic string formation in this system. We find that string formation before or at the onset of racetrack inflation is possible, but they are then inflated away. Furthermore, string formation at the end of inflation is prevented by the presence of the moduli sector. As a consequence, no strings survive racetrack inflation. (orig.)

  15. String theory in four dimensions

    International Nuclear Information System (INIS)

    Dine, M.

    1988-01-01

    A representative sample of current ideas about how one might develop a string phenomenology is presented. Some of the obstacles which lie in between string theory and contact with experiment are described. It is hoped that this volume will provide the reader with ways of thinking about string theory in four dimensions and provide tools for asking questions about string theory and ordinary physics. 102 refs

  16. The STRING database in 2011

    DEFF Research Database (Denmark)

    Szklarczyk, Damian; Franceschini, Andrea; Kuhn, Michael

    2011-01-01

    present an update on the online database resource Search Tool for the Retrieval of Interacting Genes (STRING); it provides uniquely comprehensive coverage and ease of access to both experimental as well as predicted interaction information. Interactions in STRING are provided with a confidence score...... models, extensive data updates and strongly improved connectivity and integration with third-party resources. Version 9.0 of STRING covers more than 1100 completely sequenced organisms; the resource can be reached at http://string-db.org....

  17. Instability of colliding metastable strings

    Energy Technology Data Exchange (ETDEWEB)

    Hiramatsu, Takashi [Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics; Eto, Minoru [Yamagata Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research

    2013-04-15

    We investigate the collision dynamics of two metastable strings which can be viewed as tube-like domain walls with winding numbers interpolating a false vacuum and a true vacuum. We find that depending on the relative angle and speed of two strings, instability of strings increases and the false vacuum is filled out by rapid expansion of the strings or of a remnant of the collision.

  18. Cosmic strings and galaxy formation

    Science.gov (United States)

    Bertschinger, Edmund

    1989-01-01

    The cosmogonical model proposed by Zel'dovich and Vilenkin (1981), in which superconducting cosmic strings act as seeds for the origin of structure in the universe, is discussed, summarizing the results of recent theoretical investigations. Consideration is given to the formation of cosmic strings, the microscopic structure of strings, gravitational effects, cosmic string evolution, and the formation of galaxies and large-scale structure. Simulation results are presented in graphs, and several outstanding issues are listed and briefly characterized.

  19. Instability of colliding metastable strings

    International Nuclear Information System (INIS)

    Hiramatsu, Takashi; Kobayashi, Tatsuo; Ookouchi, Yutaka; Kyoto Univ.

    2013-04-01

    We investigate the collision dynamics of two metastable strings which can be viewed as tube-like domain walls with winding numbers interpolating a false vacuum and a true vacuum. We find that depending on the relative angle and speed of two strings, instability of strings increases and the false vacuum is filled out by rapid expansion of the strings or of a remnant of the collision.

  20. Racetrack inflation and cosmic strings

    International Nuclear Information System (INIS)

    Brax, P.; Postma, M.

    2008-05-01

    We consider the coupling of racetrack inflation to matter fields as realised in the D3/D7 brane system. In particular, we investigate the possibility of cosmic string formation in this system. We find that string formation before or at the onset of racetrack inflation is possible, but they are then inflated away. Furthermore, string formation at the end of inflation is prevented by the presence of the moduli sector. As a consequence, no strings survive racetrack inflation. (orig.)

  1. Classification of three-family grand unification in string theory. II. The SU(5) and SU(6) models

    International Nuclear Information System (INIS)

    Kakushadze, Z.; Tye, S.H.

    1997-01-01

    Requiring that supersymmetric SU(5) and SU(6) grand unifications in the heterotic string theory must have three chiral families, adjoint (or higher representation) Higgs fields in the grand unified gauge group, and a non-Abelian hidden sector, we construct such string models within the framework of free conformal field theory and asymmetric orbifolds. Within this framework, we construct all such string models via Z 6 asymmetric orbifolds that include a Z 3 outerautomorphism, the latter yielding a level-three current algebra for the grand unification gauge group SU(5) or SU(6). We then classify all such Z 6 asymmetric orbifolds that result in models with a non-Abelian hidden sector. All models classified in this paper have only one adjoint (but no other higher representation) Higgs field in the grand unified gauge group. This Higgs field is neutral under all other gauge symmetries. The list of hidden sectors for three-family SU(6) string models are SU(2), SU(3), and SU(2)circle-times SU(2). In addition to these, three-family SU(5) string models can also have an SU(4) hidden sector. Some of the models have an apparent anomalous U(1) gauge symmetry. copyright 1997 The American Physical Society

  2. Propagating stress-pulses and wiggling transition revealed in string dynamics

    Science.gov (United States)

    Yao, Zhenwei

    2018-02-01

    Understanding string dynamics yields insights into the intricate dynamic behaviors of various filamentary thin structures in nature and industry covering multiple length scales. In this work, we investigate the planar dynamics of a flexible string where one end is free and the other end is subject to transverse and longitudinal motions. Under transverse harmonic motion, we reveal the propagating pulse structure in the stress profile over the string, and analyze its role in bringing the system into a chaotic state. For a string where one end is under longitudinal uniform acceleration, we identify the wiggling transition, derive the analytical wiggling solution from the string equations, and present the phase diagram.

  3. Determination of the Heterotic groups of Maize inbred lines and the ...

    African Journals Online (AJOL)

    Maize weevil (Sitophilus zeamais Motschulsky) is a major maize (Zea mays L) storage insect pest in the tropics. Fifty-two inbred lines developed for weevil resistance were crossed to two testers, A and B, to determine their heterotic groups and inheritance of resistance to maize weevil. For 10 testcrosses selected for ...

  4. A Mini-Landscape of Exact MSSM Spectra in Heterotic Orbifolds

    CERN Document Server

    Lebedev, O; Raby, S; Ramos-Sánchez, S; Ratz, M; Vaudrevange, P K S; Wingerter, A; Lebedev, Oleg; Nilles, Hans Peter; Raby, Stuart; Ramos-Sanchez, Saul; Ratz, Michael; Vaudrevange, Patrick K.S.; Wingerter, Akin

    2007-01-01

    We explore a "fertile patch" of the heterotic landscape based on a Z_6-II orbifold with SO(10) and E_6 local GUT structures. We search for models allowing for the exact MSSM spectrum. Our result is that of order 100 out of a total 3\\times 10^4 inequivalent models satisfy this requirement.

  5. Heterotic reduction of Courant algebroid connections and Einstein–Hilbert actions

    Energy Technology Data Exchange (ETDEWEB)

    Jurčo, Branislav, E-mail: jurco@karlin.mff.cuni.cz [Mathematical Institute, Faculty of Mathematics and Physics, Charles University, Prague 186 75 (Czech Republic); Vysoký, Jan, E-mail: vysoky@math.cas.cz [Institute of Mathematics of the Czech Academy of Sciences, Žitná 25, Prague 115 67 (Czech Republic); Mathematical Sciences Institute, Australian National University, Acton ACT 2601 (Australia)

    2016-08-15

    We discuss Levi-Civita connections on Courant algebroids. We define an appropriate generalization of the curvature tensor and compute the corresponding scalar curvatures in the exact and heterotic case, leading to generalized (bosonic) Einstein–Hilbert type of actions known from supergravity. In particular, we carefully analyze the process of the reduction for the generalized metric, connection, curvature tensor and the scalar curvature.

  6. Heterotic reduction of Courant algebroid connections and Einstein–Hilbert actions

    International Nuclear Information System (INIS)

    Jurčo, Branislav; Vysoký, Jan

    2016-01-01

    We discuss Levi-Civita connections on Courant algebroids. We define an appropriate generalization of the curvature tensor and compute the corresponding scalar curvatures in the exact and heterotic case, leading to generalized (bosonic) Einstein–Hilbert type of actions known from supergravity. In particular, we carefully analyze the process of the reduction for the generalized metric, connection, curvature tensor and the scalar curvature.

  7. Origin of Abelian Gauge Symmetries in Heterotic/F-theory Duality

    CERN Document Server

    Cvetic, Mirjam; Klevers, Denis; Poretschkin, Maximilian; Song, Peng

    2016-01-01

    We study aspects of heterotic/F-theory duality for compactifications with Abelian gauge symmetries. We consider F-theory on general Calabi-Yau manifolds with a rank one Mordell-Weil group of rational sections. By rigorously performing the stable degeneration limit in a class of toric models, we derive both the Calabi-Yau geometry as well as the spectral cover describing the vector bundle in the heterotic dual theory. We carefully investigate the spectral cover employing the group law on the elliptic curve in the heterotic theory. We find in explicit examples that there are three different classes of heterotic duals that have U(1) factors in their low energy effective theories: split spectral covers describing bundles with S(U(m) x U(1)) structure group, spectral covers containing torsional sections that seem to give rise to bundles with SU(m) x Z_k structure group and bundles with purely non-Abelian structure groups having a centralizer in E_8 containing a U(1) factor. In the former two cases, it is required ...

  8. Simplified pure spinor b ghost in a curved heterotic superstring background

    Energy Technology Data Exchange (ETDEWEB)

    Berkovits, Nathan [ICTP South American Institute for Fundamental Research,Instituto de Física Teórica, UNESP - Universidade Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Chandia, Osvaldo [Departamento de Ciencias, Facultad de Artes Liberales,Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez,Diagonal Las Torres 2640, Peñalolén, Santiago (Chile)

    2014-06-03

    Using the RNS-like fermionic vector variables introduced in arXiv:1305.0693, the pure spinor b ghost in a curved heterotic superstring background is easily constructed. This construction simplifies and completes the b ghost construction in a curved background of arXiv:1311.7012.

  9. String theory and quark confinement

    International Nuclear Information System (INIS)

    Polyakov, A.M.

    1998-01-01

    This article is based on a talk given at the ''Strings '97'' conference. It discusses the search for the universality class of confining strings. The key ingredients include the loop equations, the zigzag symmetry, the non-linear renormalization group. Some new tests for the equivalence between gauge fields and strings are proposed. (orig.)

  10. String theory in four dimensions

    CERN Document Server

    1988-01-01

    ``String Theory in Four Dimensions'' contains a representative collection of papers dealing with various aspects of string phenomenology, including compactifications on smooth manifolds and more general conformal field theories. Together with the lucid introduction by M. Dine, this material gives the reader a good working knowledge of our present ideas for connecting string theory to nature.

  11. String necklaces and primordial black holes from type IIB strings

    International Nuclear Information System (INIS)

    Lake, Matthew; Thomas, Steve; Ward, John

    2009-01-01

    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.

  12. Gauge origin of discrete flavor symmetries in heterotic orbifolds

    Directory of Open Access Journals (Sweden)

    Florian Beye

    2014-09-01

    Full Text Available We show that non-Abelian discrete symmetries in orbifold string models have a gauge origin. This can be understood when looking at the vicinity of a symmetry enhanced point in moduli space. At such an enhanced point, orbifold fixed points are characterized by an enhanced gauge symmetry. This gauge symmetry can be broken to a discrete subgroup by a nontrivial vacuum expectation value of the Kähler modulus T. Using this mechanism it is shown that the Δ(54 non-Abelian discrete symmetry group originates from a SU(3 gauge symmetry, whereas the D4 symmetry group is obtained from a SU(2 gauge symmetry.

  13. SUPERCOLLIDER: String test success

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    On 14 August at the Superconducting Supercollider (SSC) Laboratory in Ellis County, Texas, the Accelerator Systems String Test (ASST) successfully met its objective by operating a half-cell of five collider dipole magnets, one quadrupole magnet, and two spool pieces at the design current of 6500 amperes

  14. Help from the strings

    CERN Multimedia

    2007-01-01

    "How can the nature of basic particles be defined beyond the mechanisms presiding over their creation? Besides the standard model of particle physics - resulting from the postulations of quantum mechanics - contemporary science has pinned its hopes on the totally new unifying notion provided by the highly mathematical string theory."(2 pages)

  15. New Z3 strings

    Directory of Open Access Journals (Sweden)

    Marco A.C. Kneipp

    2016-12-01

    Full Text Available We consider a Yang–Mills–Higgs theory with the gauge group SU(3 broken to its center Z3 by two scalar fields in the adjoint representation and obtain new Z3 strings asymptotic configurations with the gauge field and magnetic field in the direction of the step operators.

  16. On exceptional instanton strings

    NARCIS (Netherlands)

    Del Zotto, M.; Lockhart, G.

    According to a recent classification of 6d (1, 0) theories within F-theory there are only six “pure” 6d gauge theories which have a UV superconformal fixed point. The corresponding gauge groups are SU(3), SO(8), F4, E6, E7, and E8. These exceptional models have BPS strings which are also instantons

  17. String perturbation theory diverges

    International Nuclear Information System (INIS)

    Gross, D.J.; Periwal, V.

    1988-01-01

    We prove that perturbation theory for the bosonic string diverges for arbitrary values of the coupling constant and is not Borel summable. This divergence is independent of the existence of the infinities that occur in the theory due to the presence of tachyons and dilaton tadpoles. We discuss the physical implications of such a divergence

  18. Transversally extended string

    International Nuclear Information System (INIS)

    Akama, Keiichi

    1988-01-01

    Starting with the space-time action of the transversally extended string, we derive its world-sheet action, which is that of a gravitational and gauge theory with matter fields on the world-sheet, with additional effects of the second fundamental quantity. (author)

  19. Interaction of solitons with a string of coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vijendra, E-mail: vsmedphysics@gmail.com; Swami, O. P., E-mail: omg1789@gmail.com; Nagar, A. K., E-mail: ajaya.nagar@gmail.com [Department of Physics, Govt. Dungar College, Bikaner, Rajasthan 334001 (India); Taneja, S., E-mail: sachintaneja9@gmail.com [Department of Radiotherapy, CHAF Bangalore, Karnataka 560007 (India)

    2016-05-06

    In this paper, we develop a theory for discrete solitons interaction with a string of coupled quantum dots in view of the local field effects. Discrete nonlinear Schrodinger (DNLS) equations are used to describe the dynamics of the string. Numerical calculations are carried out and results are analyzed with the help of matlab software. With the help of numerical solutions we demonstrate that in the quantum dots string, Rabi oscillations (RO) are self trapped into stable bright Rabi solitons. The Rabi oscillations in different types of nanostructures have potential applications to the elements of quantum logic and quantum memory.

  20. Lectures on strings and dualities

    International Nuclear Information System (INIS)

    Vafa, C.

    1997-01-01

    In this set of lectures I review recent developments in string theory emphasizing their non-perturbative aspects and their recently discovered duality symmetries. The goal of the lectures is to make the recent exciting developments in string theory accessible to those with no previous background in string theory who wish to join the research effort in this area. Topics covered include a brief review of string theory, its compactifications, solitons and D-branes, black hole entropy and wed of string dualities. (author)