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.)
EFFECTIVE ACTIONS FOR HETEROTIC STRING THEORY
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.
Courant algebroid connections and string effective actions
Jurčo, B.
2017-01-01
Courant algebroids are a natural generalization of quadratic Lie algebras, appearing in various contexts in mathematical physics. A connection on a Courant algebroid gives an analogue of a covariant derivative compatible with a given fiber-wise metric. Imposing further conditions resembling standard Levi-Civita connections, one obtains a class of connections whose curvature tensor in certain cases gives a new geometrical description of equations of motion of low energy effective action of str...
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.)
The effective action of a BPS Alice string
Energy Technology Data Exchange (ETDEWEB)
Chatterjee, Chandrasekhar; Nitta, Muneto [Keio University, Department of Physics, and Research and Education Center for Natural Sciences, Yokohama, Kanagawa (Japan)
2017-11-15
Recently a BPS Alice string has been found in a U(1) x SO(3) gauge theory coupled with three charged complex scalar fields in the triplet representation (in JHEP 1709:046 arXiv:1703.08971 [hep-th], 2017). It is a half BPS state preserving a half of the supercharges when embedded into a supersymmetric gauge theory. In this paper, we study zero modes of a BPS Alice string. After presenting U(1) and translational zero modes, we construct the effective action of these modes. In contrast to a previous analysis of the conventional Alice string for which only large distance behaviors are known, we can exactly perform a calculation in the full space thanks to the BPS properties. (orig.)
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.)
On non-BPS effective actions of string theory
Hatefi, Ehsan
2018-05-01
We discuss some physical prospective of the non-BPS effective actions of type IIA and IIB superstring theories. By dealing with all complete three and four point functions, including a closed Ramond-Ramond string (in terms of both its field strength and its potential), gauge (scalar) fields as well as a real tachyon and under symmetry structures, we find various restricted world volume and bulk Bianchi identities. The complete forms of the non-BPS scattering amplitudes including their Chan-Paton factors are elaborated. All the singularity structures of the non-BPS amplitudes, their all order α ' higher-derivative corrections, their contact terms and various modified Bianchi identities are derived. Finally, we show that scattering amplitudes computed in different super-ghost pictures are compatible when suitable Bianchi identities are imposed on the Ramond-Ramond fields. Moreover, we argue that the higher-derivative expansion in powers of the momenta of the tachyon is universal.
Variational methods and effective actions in string models
International Nuclear Information System (INIS)
Dereli, T.; Tucker, R.W.
1987-01-01
Effective actions motivated by zero-order and first-order actions are examined. Particular attention is devoted to a variational procedure that is consistent with the structure equations involving the Lorentz connection. Attention is drawn to subtleties that can arise in varying higher-order actions and an efficient procedure developed to handle these cases using the calculus of forms. The effect of constrained variations on the field equations is discussed. (author)
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
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.
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
Ambiguity in determining the effective action for string-corrected Einstein gravity
International Nuclear Information System (INIS)
Hochberg, D.; Shimada, T.
1986-11-01
The authors attempt to clarify some issues dealing with the determination of some of the coefficients appearing in the low-energy gravitational effective action for closed strings. In particular, the coefficients of the Rsub(μv) 2 and R 2 terms of the quadratic curvature corrections to the Einstein-Hilbert action are shown not to be determined by matching the on-shell S-matrices of the effective theory with that of the string theories. The mechanism responsible for the ambiguity of these coefficients is revealed as a cancellation among the contact, exchange and point-insertion terms contributing to the tree S-matrix of the effective local theory. Although ghost poles will appear in the graviton propagator for general quadratic curvature corrections, the effective theory remains unitary. The manifest absence of ghosts is achieved by choosing the Gauss-Bonnet combination of quadratic curvature terms, but the string does not single out this combination over any other. (author)
String states, loops and effective actions in noncommutative field theory and matrix models
Directory of Open Access Journals (Sweden)
Harold C. Steinacker
2016-09-01
Full Text Available Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
String states, loops and effective actions in noncommutative field theory and matrix models
Energy Technology Data Exchange (ETDEWEB)
Steinacker, Harold C., E-mail: harold.steinacker@univie.ac.at
2016-09-15
Refining previous work by Iso, Kawai and Kitazawa, we discuss bi-local string states as a tool for loop computations in noncommutative field theory and matrix models. Defined in terms of coherent states, they exhibit the stringy features of noncommutative field theory. This leads to a closed form for the 1-loop effective action in position space, capturing the long-range non-local UV/IR mixing for scalar fields. The formalism applies to generic fuzzy spaces. The non-locality is tamed in the maximally supersymmetric IKKT or IIB model, where it gives rise to supergravity. The linearized supergravity interactions are obtained directly in position space at one loop using string states on generic noncommutative branes.
Modified Steiner functional string action
International Nuclear Information System (INIS)
Baillie, C.F.; Johnston, D.A.
1992-01-01
It has recently been suggested by Ambartzumian et al. that the modified Steiner functional has desirable properties as an action for random surfaces and hence string world sheets. We perform a simulation of this action on a dynamically triangulated random surface to investigate this claim and find that the surfaces are in a flat phase
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)
Poisson-Lie T-duality of string effective actions: A new approach to the dilaton puzzle
Czech Academy of Sciences Publication Activity Database
Jurčo, B.; Vysoký, Jan
2018-01-01
Roč. 130, August (2018), s. 1-26 ISSN 0393-0440 Institutional support: RVO:67985840 Keywords : Poisson-Lie T-duality * string effective actions * dilaton field Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.819, year: 2016 https://www.sciencedirect.com/science/article/pii/S0393044018301748?via%3Dihub
Poisson-Lie T-duality of string effective actions: A new approach to the dilaton puzzle
Czech Academy of Sciences Publication Activity Database
Jurčo, B.; Vysoký, Jan
2018-01-01
Roč. 130, August (2018), s. 1-26 ISSN 0393-0440 Institutional support: RVO:67985840 Keywords : Poisson-Lie T- dual ity * string effective actions * dilaton field Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.819, year: 2016 https://www.sciencedirect.com/science/article/pii/S0393044018301748?via%3Dihub
Purely cubic action for string field theory
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.
String loop effect on the BRST charge
International Nuclear Information System (INIS)
Das, A.; Nishino, H.
1987-07-01
An effective BRST charge Q BRST which incorporates the string one-loop corrections is presented for the closed bosonic string in an arbitrary background. The effective σ-model action which leads to such a Q BRST is obtained and some consequences are discussed. (author). 14 refs, 1 fig
Effective lagrangian from bosonic string field theory
International Nuclear Information System (INIS)
Nakazawa, Naohito
1987-01-01
We investigate the low-energy effective action from the string field theoretical view point. The low-energy effective lagrangian for the massless mode of bosonic string is determined to the order of α'. We find a term which can not be determined from the S-matrix approach. (author)
On the relationship between string low-energy effective actions and O(α'3) σ-model β-functions
International Nuclear Information System (INIS)
Jack, I.; Ross, D.A.; Jones, D.R.T.
1988-01-01
We examine in detail the connection between low-energy string effective actions and the σ-model β-functions up to O(α' 3 ) in the torsion-free case. In particular we show that the relationship between, on the one hand, the equations of motion derived from the O(α' 3 ) string effective action, and, on the other hand, the O(α' 3 ) σ-model β-functions necessarily involves derivative operators acting on the β-functions. (orig.)
Boundary terms in Nambu-Goto string action
Hadasz, Leszek; Wegrzyn, Pawel
1994-01-01
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 the boundary term reduces to the Gauss-Bonnet term, a stability analysis is performed on the rotating rigid string so...
Open rigid string with the Gauss-Bonnet term in action
International Nuclear Information System (INIS)
Nesterenko, V.V.; Pirozhenko, I.G.
1998-01-01
The effect of the Gaussian curvature in the rigid string action on the interquark potential is investigated. The linearized equations of motion and boundary conditions, following from the modified string action, are obtained. The equation, defining the eigenfrequency spectrum of the string oscillations is derived. On this basis the interquark potential generated by the string is calculated in one-loop approximation. A substantial influence of the topological term in the string action on the interquark potential at the distances of hadronic size order or less is revealed
Boundary terms in the Nambu-Goto string action
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.
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
String perturbation theory and effective Lagrangians
International Nuclear Information System (INIS)
Klebanov, I.
1987-09-01
We isolate logarithmic divergences from bosonic string amplitudes on a disc. These divergences are compared with 'tadpole' divergences in the effective field theory with a cosmological term, which also contains an effective potential for the dilation. Also, corrections to β-functions are compared with variations of the effective action. In both cases we find an inconsistency between the two. This is a serious problem which could undermine our ability to remove divergences from the bosonic string
Gravitational effects of global strings
International Nuclear Information System (INIS)
Aryal, M.; Everett, A.E.
1986-01-01
We have obtained the gravitational field, in the weak-field approximation, of cosmic strings formed in a phase transition in which a global symmetry is broken (global strings). The effect of this field on light rays passing a global string is found, and the resulting formation of double images and production of discontinuities in the microwave background temperature compared with the corresponding results for gauge strings. There are some differences in the case of global strings, reflecting the fact that the space surrounding such strings is not purely conical. However, the differences between gauge and global strings with masses suitable to explain galaxy formation are small, and the task of distinguishing them observationally appears difficult at best
Effective string theory and QCD scattering amplitudes
International Nuclear Information System (INIS)
Makeenko, Yuri
2011-01-01
QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luescher term, and discuss an application to meson scattering amplitudes in QCD.
Gauge invariant actions for string models
International Nuclear Information System (INIS)
Banks, T.
1986-06-01
String models of unified interactions are elegant sets of Feynman rules for the scattering of gravitons, gauge bosons, and a host of massive excitations. The purpose of these lectures is to describe the progress towards a nonperturbative formulation of the theory. Such a formulation should make the geometrical meaning of string theory manifest and explain the many ''miracles'' exhibited by the string Feynman rules. There are some new results on gauge invariant observables, on the cosmological constant, and on the symmetries of interacting string field theory. 49 refs
International Nuclear Information System (INIS)
Hecht, Michael
2011-01-01
This thesis addresses two different topics within the field of string theory. In the first part it is shown how Hodge-theoretic methods in conjunction with open string mirror symmetry can be used to compute non-perturbative effective superpotential couplings for type II/F-theory compactifications with D-branes and fluxes on compact Calabi-Yau manifolds. This is achieved by studying the at structure of operators which derives from the open/closed Β-model geometry. We analyze the variation of mixed Hodge structure of the relative cohomology induced by a family of divisors, which is wrapped by a D7-brane. This leads to a Picard-Fuchs system of differential operators, which can be used to compute the moduli dependence of the superpotential couplings as well as the mirror maps at various points in the open/closed deformation space. These techniques are used to obtain predictions for genuine A-model Ooguri-Vafa invariants of special Lagrangian submanifolds in compact Calabi-Yau geometries and real enumerative invariants of on-shell domain wall tensions. By an open/closed duality the system of differential equations can also be obtained from a gauged linear σ-model, which describes a non-compact Calabi-Yau four-fold compactification without branes. This is used in the examples of multi-parameter models to study the various phases of the combined open/closed deformation space. It is furthermore shown how the brane geometry can be related to a F-theory compactification on a compact Calabi-Yau four-fold, where the Hodge-theoretic techniques can be used to compute the G-flux induced Gukov-Vafa-Witten potential. The dual F-theory picture also allows to conjecture the form of the Kaehler potential on the full open/closed deformation space. In the second part we analyze the background dependence of theories which derive from multiple wrapped M5-branes. Using the Kontsevich-Soibelman wall-crossing formula and the theory of mock modular forms we derive a holomorphic anomaly
Energy Technology Data Exchange (ETDEWEB)
Hecht, Michael
2011-10-20
This thesis addresses two different topics within the field of string theory. In the first part it is shown how Hodge-theoretic methods in conjunction with open string mirror symmetry can be used to compute non-perturbative effective superpotential couplings for type II/F-theory compactifications with D-branes and fluxes on compact Calabi-Yau manifolds. This is achieved by studying the at structure of operators which derives from the open/closed {beta}-model geometry. We analyze the variation of mixed Hodge structure of the relative cohomology induced by a family of divisors, which is wrapped by a D7-brane. This leads to a Picard-Fuchs system of differential operators, which can be used to compute the moduli dependence of the superpotential couplings as well as the mirror maps at various points in the open/closed deformation space. These techniques are used to obtain predictions for genuine A-model Ooguri-Vafa invariants of special Lagrangian submanifolds in compact Calabi-Yau geometries and real enumerative invariants of on-shell domain wall tensions. By an open/closed duality the system of differential equations can also be obtained from a gauged linear {sigma}-model, which describes a non-compact Calabi-Yau four-fold compactification without branes. This is used in the examples of multi-parameter models to study the various phases of the combined open/closed deformation space. It is furthermore shown how the brane geometry can be related to a F-theory compactification on a compact Calabi-Yau four-fold, where the Hodge-theoretic techniques can be used to compute the G-flux induced Gukov-Vafa-Witten potential. The dual F-theory picture also allows to conjecture the form of the Kaehler potential on the full open/closed deformation space. In the second part we analyze the background dependence of theories which derive from multiple wrapped M5-branes. Using the Kontsevich-Soibelman wall-crossing formula and the theory of mock modular forms we derive a holomorphic
Effective string dynamics in large N QCD
Energy Technology Data Exchange (ETDEWEB)
Iroshnikov, G.S. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]|[Moskow Inst. of Physics and Technology, Moscow (Russian Federation)
1995-05-01
The semiclassical 1/N expansion in the strong coupling regime for spinor quarks was developed and the form of effective action was obtained. An extremum of the effective action that arises in the calculation of the hadronic correlation functions in the large N limit corresponds to a topologically non-trivial configuration of the gauge field. This configuration forms a chromoelectric Nambu string with additional spinor terms that contain in particular the Polyakov spinor factor. In the case when real quarks forming hadrons are replaced by scalar particles the above correlators yield the standard dual resonance amplitudes. (author). 10 refs, 1 fig.
String loop divergences and effective lagrangians
International Nuclear Information System (INIS)
Fischler, W.; Klebanov, I.; Susskind, L.
1988-01-01
We isolate logarithmic divergences from bosonic string amplitudes on a disc. These divergences are compared with 'tadpole' divergences in the effective field theory, with a covariant cosmological term implied by the counting of string coupling constants. We find an inconsistency between the two. This might be a problem in eliminating divergences from the bosonic string. (orig.)
String creation, D-branes and effective field theory
International Nuclear Information System (INIS)
Hung Lingyan
2008-01-01
This paper addresses several unsettled issues associated with string creation in systems of orthogonal Dp-D(8-p) branes. The interaction between the branes can be understood either from the closed string or open string picture. In the closed string picture it has been noted that the DBI action fails to capture an extra RR exchange between the branes. We demonstrate how this problem persists upon lifting to M-theory. These D-brane systems are analysed in the closed string picture by using gauge-fixed boundary states in a non-standard lightcone gauge, in which RR exchange can be analysed precisely. The missing piece in the DBI action also manifests itself in the open string picture as a mismatch between the Coleman-Weinberg potential obtained from the effective field theory and the corresponding open string calculation. We show that this difference can be reconciled by taking into account the superghosts in the (0+1) effective theory of the chiral fermion, that arises from gauge fixing the spontaneously broken world-line local supersymmetries
On the Kählerian symmetries of the two-loop action of the effective string theory
Ozkurt, S S
2003-01-01
Sometimes ago, it has been proposed in a paper by N.Kaloper and K.A.Meissner (\\PR {\\bf D56} (1997) 7940) that if one makes local redefinitions of fields, it does not change the equations of motion (in the redefined fields); however, this comment has not generally been accepted, namely, the redefined fields satisfy different equations of motion. For this reason, in this paper, it is proved that the whole action can be written as a square of the zeroth-order field equations. In this way, we show that any solution of the zeroth-order field equations, which has some K\\"{a}hler symmetry, at the same time, is also a solution of the two-loop equations.
A Chern-Simons-like action for closed-string field theory
International Nuclear Information System (INIS)
Taylor, C.C.
1989-01-01
A Chern-Simons-like action is proposed for closed-string field theory. The action involves auxiliary fields of arbitrary ghost number and is defined in terms of the closed-string operations ∫, Q and *, analogous to those introduced by Witten in the construction of open-string field theory. The action is an extension of one proposed for free closed strings and bears a formal relationship to 2 + 1 gravity analogous to that between open-string field theory and (2 + 1)-dimensional Yang-Mills theory. (author)
Zhu, Qin
2013-01-01
Affordances mean opportunities for action. These affordances are important for sports performance and relevant to the abilities developed by skilled athletes. In racquet sports such as badminton, different players prefer widely different string tension because it is believed to provide opportunities for effective strokes. The current study examined whether badminton players can perceive the affordance of string tension for power strokes and whether the perception of affordance itself changed as a function of skill level. The results showed that string tension constrained the striking performance of both novice and recreational players, but not of expert players. When perceptual capability was assessed, perceptual mode did not affect perception of the optimal string tension. Skilled players successfully perceived the affordance of string tension, but only experts were concerned about saving energy. Our findings demonstrated that perception of the affordance of string tension in badminton was determined by action abilities. Furthermore, experts could adjust the action to maintain a superior level of performance based on the perception of affordance.
String effects in the 3d gauge Ising model
International Nuclear Information System (INIS)
Caselle, Michele; Panero, Marco; Hasenbusch, Martin
2003-01-01
We compare the predictions of the effective string description of confinement with a set of Monte Carlo data for the 3d gauge Ising model at finite temperature. Thanks to a new algorithm which makes use of the dual symmetry of the model we can reach very high precisions even for large quark-antiquark distances. We are thus able to explore the large R regime of the effective string. We find that for large enough distances and low enough temperature the data are well described by a pure bosonic string. As the temperature increases higher order corrections become important and cannot be neglected even at large distances. These higher order corrections seem to be well described by the Nambu-Goto action truncated at the first perturbative order. (author)
Testing effective string models of black holes with fixed scalars
International Nuclear Information System (INIS)
Krasnitz, M.; Klebanov, I.R.
1997-01-01
We solve the problem of mixing between the fixed scalar and metric fluctuations. First, we derive the decoupled fixed scalar equation for the four-dimensional black hole with two different charges. We proceed to the five-dimensional black hole with different electric (one-brane) and magnetic (five-brane) charges, and derive two decoupled equations satisfied by appropriate mixtures of the original fixed scalar fields. The resulting greybody factors are proportional to those that follow from coupling to dimension (2,2) operators on the effective string. In general, however, the string action also contains couplings to chiral operators of dimension (1,3) and (3,1), which cause disagreements with the semiclassical absorption cross sections. Implications of this for the effective string models are discussed. copyright 1997 The American Physical Society
Boundary operators in effective string theory
Energy Technology Data Exchange (ETDEWEB)
Hellerman, Simeon [Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan); Swanson, Ian [Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)
2017-04-13
Various universal features of relativistic rotating strings depend on the organization of allowed local operators on the worldsheet. In this paper, we study the set of Neumann boundary operators in effective string theory, which are relevant for the controlled study of open relativistic strings with freely moving endpoints. Relativistic open strings are thought to encode the dynamics of confined quark-antiquark pairs in gauge theories in the planar approximation. Neumann boundary operators can be organized by their behavior under scaling of the target space coordinates X{sup μ}, and the set of allowed X-scaling exponents is bounded above by +1/2 and unbounded below. Negative contributions to X-scalings come from powers of a single invariant, or “dressing' operator, which is bilinear in the embedding coordinates. In particular, we show that all Neumann boundary operators are dressed by quarter-integer powers of this invariant, and we demonstrate how this rule arises from various ways of regulating the short-distance singularities of the effective theory.
Effects of the image universe on cosmic strings
International Nuclear Information System (INIS)
Vachaspati, T.; Rees, M.
1990-01-01
We investigate some of the cosmological effects of the gravitational attraction of straight cosmic strings that arises due to the conical geometry of the string. Although this effect is second order in Newton's gravitational constant, its effects in the early universe can be significant. We find that the image masses responsible for this second order attraction effectively 'fill up' the volume deficit due to the conical geometry of a static straight string. A moving string also experiences a frictional force due to the images and this provides a mechanism for energy dissipation. The energy loss due to the image effect is comparable to the energy loss in gravitational radiation for strings on the size of the horizon scale but is probably not important when compared to the energy loss due to loop production. The image effect can also become important when a string comes close to a black hole. Our analysis of these effects is newtonian. (orig.)
Closed string field theory: Quantum action and the Batalin-Vilkovsky master equation
International Nuclear Information System (INIS)
Zwiebach, B.
1993-01-01
The complete quantum theory of covariant closed strings is constructed in detail. The nonpolynomial action is defined by elementary vertices satisfying recursion relations that give rise to Jacobi-like identities for an infinite chain of string field products. The genus zero string field algebra is the homotopy Lie algebra L ∞ encoding the gauge symmetry of the classical theory. The higher genus algebraic structure implies the Batalin-Vilkovisky (BV) master equation and thus consistent BRST quantization of the quantum action. From the L ∞ algebra, and the BV equation on the off-shell state space we derive the L ∞ algebra, and the BV equation on physical states that were recently constructed in d=2 string theory. The string diagrams are surfaces with minimal area metrics, foliated by closed geodesics of length 2π. These metrics generalize quadratic differentials in that foliation bands can cross. The string vertices are succinctly characterized; they include the surfaces whose foliation bands are all of height smaller than 2π. (orig.)
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
First order actions for gravitational systems, strings and membranes
International Nuclear Information System (INIS)
Lindstrom, U.
1988-01-01
The authors discuss first order actions in general and the construction of first order actions by eliminating Lagrange multipliers in particular. A number of first order actions for gravitational theories are presented. Part of the article reviews first order actions, some of them well-known and some lesser known. New examples of first order actions include Weyl-invariant actions for membranes, with and without rigidity terms, as well as for Abelian and non-Abelian Born-Infeld actions in two dimensions
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.
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
On effective theories of topological strings
International Nuclear Information System (INIS)
Elitzur, S.; Forge, A.; Rabinovici, E.
1992-01-01
We study the construction of effective target-space theories of topological string theories. The example of the CP1 topological sigma model is analysed in detail. An effective target-space theory whose correlation functions are defined by the sum over connected Riemann surfaces of all genera is found to be itself topological. The values of the couplings of this effective theory are expressed in terms of those of the world-sheet theory for a general CP1-like world-sheet model. Any model of this type can be obtained as an effective theory. The definition of the effective theory's expectation values as a sum over disconnected surfaces as well, is shown not to be compatible with those of a topological theory, at least as long as the connectivity of the target space is kept fixed. Dilaton-type couplings emerge in the full lagrangian realization of the moduli space of topological theories with n observables. En route, we encounter a nonperturbative duality, an equivalence of theories with different world-sheets and discuss the relation between the cosmological constant in these finite theories and the zero-point function. (orig.)
Action-angle variables for the massless relativistic string in 1+1 dimensions
International Nuclear Information System (INIS)
Soederberg, B.; Andersson, B.; Gustafson, G.
1985-01-01
In this paper the Poisson bracket algebra for the open massless relativistic string in the one-space- and one-time-dimensional case is considered. In order to characterize the orbit of the system the directrix function, i.e., the orbit of one of the endpoints of the string, is used. It turns out that the Poisson bracket algebra is of a very simple form in terms of the parameters of the directrix function. We use these results to construct action-angle variables for the general motion of the string. The variables are different for different Lorentz frames, with a continuous dependence. The action-angle variables of the center-of-mass frame and of the light-cone frames are of particular interest with respect to the simplicity of the Poincare generators and the physical interpretation. For the light-cone frame variables the equivalence to a set of indistinguishable oscillators is shown, for which an excitation corresponds to an instantaneous momentum transfer to an endpoint of the string
The effective supergravity of little string theory
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.
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.)
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
Effects of the pion string at heavy ion collisions
Mao, Hong
2005-01-01
We study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy square root s=5.5 TeV. We follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. We will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p21 Me V.
Wilsonian effective action of superstring theory
Energy Technology Data Exchange (ETDEWEB)
Sen, Ashoke [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); Homi Bhabha National Institute,Training School Complex, Anushakti Nagar, Mumbai 400085 (India)
2017-01-25
By integrating out the heavy fields in type II or heterotic string field theory one can construct the effective action for the light fields. This effective theory inherits all the algebraic structures of the parent theory and the effective action automatically satisfies the Batalin-Vilkovisky quantum master equation. This theory is manifestly ultraviolet finite, has only light fields as its explicit degrees of freedom, and the Feynman diagrams of this theory reproduce the exact scattering amplitudes of light states in string theory to any arbitrary order in perturbation theory. Furthermore in this theory the degrees of freedom of light fields above certain energy scale are also implicitly integrated out. This energy scale is determined by a particular parameter labelling a family of equivalent actions, and can be made arbitrarily low, leading to the interpretation of the effective action as the Wilsonian effective action.
Nambu sigma model and effective membrane actions
Energy Technology Data Exchange (ETDEWEB)
Jurco, Branislav, E-mail: jurco@karlin.mff.cuni.cz [Mathematical Institute, Charles University, Prague 186 75 (Czech Republic); Schupp, Peter, E-mail: p.schupp@jacobs-university.de [Jacobs University Bremen, 28759 Bremen (Germany); Maxwell Institute for Mathematical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, Scotland (United Kingdom)
2012-07-09
We propose an effective action for a p{sup Prime }-brane with open p-branes ending on it. The action has dual descriptions similar to the commutative and non-commutative ones of the DBI action for D-branes and open strings. The Poisson structure governing the non-commutativity of the D-brane is replaced by a Nambu structure and the open-closed string relations are generalized to the case of p-branes utilizing a novel Nambu sigma model description of p-branes. In the case of an M5-brane our action interpolates between M5-actions already proposed in the literature and matrix-model like actions involving Nambu structures.
Nambu sigma model and effective membrane actions
International Nuclear Information System (INIS)
Jurčo, Branislav; Schupp, Peter
2012-01-01
We propose an effective action for a p ′ -brane with open p-branes ending on it. The action has dual descriptions similar to the commutative and non-commutative ones of the DBI action for D-branes and open strings. The Poisson structure governing the non-commutativity of the D-brane is replaced by a Nambu structure and the open-closed string relations are generalized to the case of p-branes utilizing a novel Nambu sigma model description of p-branes. In the case of an M5-brane our action interpolates between M5-actions already proposed in the literature and matrix-model like actions involving Nambu structures.
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.)
Neutrino Majorana masses from string theory instanton effects
International Nuclear Information System (INIS)
Ibanez, Luis E.; Uranga, Angel M.
2007-01-01
Finding a plausible origin for right-handed neutrino Majorana masses in semirealistic compactifications of string theory remains one of the most difficult problems in string phenomenology. We argue that right-handed neutrino Majorana masses are induced by non-perturbative instanton effects in certain classes of string compactifications in which the U(1) B-L gauge boson has a Stueckelberg mass. The induced operators are of the form e -U ν R ν R where U is a closed string modulus whose imaginary part transforms appropriately under B-L. This mass term may be quite large since this is not a gauge instanton and Re U is not directly related to SM gauge couplings. Thus the size of the induced right-handed neutrino masses could be a few orders of magnitude below the string scale, as phenomenologically required. It is also argued that this origin for neutrino masses would predict the existence of R-parity in SUSY versions of the SM. Finally we comment on other phenomenological applications of similar instanton effects, like the generation of a μ-term, or of Yukawa couplings forbidden in perturbation theory
Non-perturbative effects and the refined topological string
Energy Technology Data Exchange (ETDEWEB)
Hatsuda, Yasuyuki [DESY Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Marino, Marcos [Geneve Univ. (Switzerland). Dept. de Physique Theorique et Section de Mathematiques; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst.; Nagoya Univ. (Japan). Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics
2013-06-15
The partition function of ABJM theory on the three-sphere has non-perturbative corrections due to membrane instantons in the M-theory dual. We show that the full series of membrane instanton corrections is completely determined by the refined topological string on the Calabi-Yau manifold known as local P{sup 1} x P{sup 1}, in the Nekrasov-Shatashvili limit. Our result can be interpreted as a first-principles derivation of the full series of non-perturbative effects for the closed topological string on this Calabi-Yau background. Based on this, we make a proposal for the non-perturbative free energy of topological strings on general, local Calabi-Yau manifolds.
Spring or string: does tendon elastic action influence wing muscle mechanics in bat flight?
Konow, Nicolai; Cheney, Jorn A; Roberts, Thomas J; Waldman, J Rhea S; Swartz, Sharon M
2015-10-07
Tendon springs influence locomotor movements in many terrestrial animals, but their roles in locomotion through fluids as well as in small-bodied mammals are less clear. We measured muscle, tendon and joint mechanics in an elbow extensor of a small fruit bat during ascending flight. At the end of downstroke, the tendon was stretched by elbow flexion as the wing was folded. At the end of upstroke, elastic energy was recovered via tendon recoil and extended the elbow, contributing to unfurling the wing for downstroke. Compared with a hypothetical 'string-like' system lacking series elastic compliance, the tendon spring conferred a 22.5% decrease in muscle fascicle strain magnitude. Our findings demonstrate tendon elastic action in a small flying mammal and expand our understanding of the occurrence and action of series elastic actuator mechanisms in fluid-based locomotion. © 2015 The Author(s).
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)
Effects of the pion string at heavy ion collisions
International Nuclear Information System (INIS)
Mao Hong; Li Yunde; East China Normal Univ., Shanghai
2005-01-01
The authors study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy √s=5.5 TeV. The authors follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. The authors will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p-143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p-21 MeV. (authors)
Topological Casimir effect in compactified cosmic string spacetime
International Nuclear Information System (INIS)
De Mello, E R Bezerra; Saharian, A A
2012-01-01
We investigate the Wightman function, the vacuum expectation values of the field squared and the energy-momentum tensor for a massive scalar field with general curvature coupling in the generalized cosmic string geometry with a compact dimension along its axis. The boundary condition along the compactified dimension is taken in general form with an arbitrary phase. The vacuum expectation values are decomposed into two parts. The first one corresponds to the uncompactified cosmic string geometry and the second one is the correction induced by the compactification. The asymptotic behavior of the vacuum expectation values of the field squared, energy density and stresses is investigated near the string and at large distances. We show that the nontrivial topology due to the cosmic string enhances the vacuum polarization effects induced by the compactness of spatial dimension for both the field squared and the vacuum energy density. A simple formula is given for the part of the integrated topological Casimir energy induced by the planar angle deficit. The results are generalized for a charged scalar field in the presence of a constant gauge field. In this case, the vacuum expectation values are periodic functions of the component of the vector potential along the compact dimension. (paper)
A proposal for an effective interacting field theory of open and closed strings
International Nuclear Information System (INIS)
Baulieu, L.; Grossman, B.
1987-01-01
We propose the use of the reggeon-pomeron vertex to obtain an effective field theory for open and closed strings. We suggest that closed string fields are necessary in order to go off-shell in an open string field theory. We then find that the closed string fields satisfy the Virasoro constraints (including equal number of left and right movers) in an appropriate choice of gauge. (orig.)
Cosmological string theory with thermal energy
International Nuclear Information System (INIS)
Shiraishi, Kiyoshi.
1988-09-01
An attempt to construct a cosmological scenario directly from string theory is made. Cosmological string theory was presented by Antoniadis, Bachas, Ellis and Nanopoulos. They also expect loop effects on cosmological string theory. In this paper, we point out the other importance of the one-loop effect, the finite temperature effect. The equations of motion for background geometry at finite temperature is given. We address a problem on derivation of the effective action at non-zero temperature. (author)
Differentiating G-inflation from string gas cosmology using the effective field theory approach
Energy Technology Data Exchange (ETDEWEB)
He, Minxi; Liu, Junyu; Lu, Shiyun; Cai, Yi-Fu [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhou, Siyi; Wang, Yi [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Brandenberger, Robert, E-mail: hmxz0@mail.ustc.edu.cn, E-mail: jliu2@caltech.edu, E-mail: shiyun@mail.ustc.edu.cn, E-mail: zhousiyi1@gmail.com, E-mail: yifucai@ustc.edu.cn, E-mail: phyw@ust.hk, E-mail: rhb@physics.mcgill.ca [Department of Physics, McGill University, Montréal, Quebec H3A 2T8 (Canada)
2016-12-01
A characteristic signature of String Gas Cosmology is primordial power spectra for scalar and tensor modes which are almost scale-invariant but with a red tilt for scalar modes but a blue tilt for tensor modes. This feature, however, can also be realized in the so-called G-inflation model, in which Horndeski operators are introduced which leads to a blue tensor tilt by softly breaking the Null Energy Condition. In this article we search for potential observational differences between these two cosmologies by performing detailed perturbation analyses based on the Effective Field Theory approach. Our results show that, although both two models produce blue tilted tensor perturbations, they behave differently in three aspects. Firstly, String Gas Cosmology predicts a specific consistency relation between the index of the scalar modes n {sub s} and that of tensor ones n {sub t} , which is hard to be reproduced by G-inflation. Secondly, String Gas Cosmology typically predicts non-Gaussianities which are highly suppressed on observable scales, while G-inflation gives rise to observationally large non-Gaussianities because the kinetic terms in the action become important during inflation. However, after finely tuning the model parameters of G-inflation it is possible to obtain a blue tensor spectrum and negligible non-Gaussianities with a degeneracy between the two models. This degeneracy can be broken by a third observable, namely the scale dependence of the nonlinearity parameter, which vanishes for G-inflation but has a blue tilt in the case of String Gas Cosmology. Therefore, we conclude that String Gas Cosmology is in principle observationally distinguishable from the single field inflationary cosmology, even allowing for modifications such as G-inflation.
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...
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.
Inflation and cosmic strings in models with dynamical symmetry breaking
International Nuclear Information System (INIS)
Matheson, A.M.; Brandenberger, R.H.
1989-01-01
We derive the effective action for the composite field which in dynamical symmetry breaking plays the role of the Higgs field. We show that this effective action does not give rise to inflation. It is, however, possible to obtain topological defects such as cosmic strings. There will be fermionic zero modes trapped on the strings, and the strings will therefore be superconducting in a generalized sense. (orig.)
International Nuclear Information System (INIS)
DeWitt, B.
1987-01-01
The concept of the effective action in quantum field theory was introduced into physics by Julian Schwinger in 1954. The effective action summarizes, in a single functional, all the quantum properties of the fields under consideration. The functional derivative of the effective action yields the effective field equations, which replace the classical field equations as descriptors of the dynamical behavior of quantized fields. Solutions of these equations are 'in-out' matrix elements of the field operators and, when substituted back into the effective action itself, yield logarithms of the corresponding 'in-out' amplitudes. The classical field equations are gauge covariant, a fact that derives from the gauge invariance of the classical action. One has learned how to construct effective actions that are similarly gauge invariant (in each order of perturbation theory) and that yield effective field equations having the covariance properties of their classical analogs. Despite this advance, problems remain, stemming from the fact that there is not one but an infinite number of gauge invariant effective actions, one for every background-covariant choice of supplementary conditions and ghost fields. Vilkovisky (1984) has argued persuasively that by requiring additionally that the effective action be invariant under local invertible changes in the choice of basic field variables, one can construct a natural unique gauge invariant effective action. This lecture will examine Vilkovisky's ideas. 3 refs
Gravitational effects of cosmic strings in Friedmann universes
International Nuclear Information System (INIS)
Veeraraghavan, S.
1988-01-01
Cosmic strings have been invoked recently as a possible source of the primordial density fluctuations in matter which gave rise to large-scale structure by the process of gravitational collapse. If cosmic strings did indeed seed structure formation then they would also leave an observable imprint upon the microwave and gravitational wave backgrounds, and upon structure on the very largest scales. In this work, the energy-momentum tensor appropriate to a cosmic string configuration in the flat Friedmann universe is first obtained and then used in the linearized Einstein equations to obtain the perturbations of the background space-time and the ambient matter. The calculation is full self-consistent to linear order because it takes into account compensation, or the response of the ambient matter density field to the presence of the string configuration, and is valid for an arbitrarily curved and moving configuration everywhere except very close to a string segment. The single constraint is that the dimensionless string tension Gμ/c 2 must be small compared to unity, but this condition is satisfied in any theory that leads to strings of cosmological relevance. The gravitational wave spectrum and the microwave background temperature fluctuations from a single infinite straight and static string are calculated. The statistically expected fluctuations from an ensemble of such strings with a mean density equal to that found in computer simulations of the evolution of string networks is also calculated. These fluctuations are compared with the observational data on the microwave background to constrain Gμ. Lastly, the role of infinite strings in the formation of the large-scale structure on scales of tens of Megaparsecs observed in deep redshift surveys is examined
The fuel string relocation effect - why the Bruce reactors were derated
Energy Technology Data Exchange (ETDEWEB)
Gold, M; Farooqui, M Z; Adebiyi, A S; Chu, R Y; Le, N T; Oliva, A F [Ontario Hydro, Toronto, ON (Canada); Balog, G; Qu, T; DeBuda, P G [Ontario Hydro, Tiverton, ON (Canada). Bruce Nuclear Generating Station-A
1996-12-31
In the CANDU Safety Analysis process, a series of design basis accidents are chosen and analyzed to confirm safety system effectiveness. Of all the postulated accidents, the Large Break Loss of Coolant Accident (LBLOCA) - a postulated break in the Heat Transport System piping near a component that services a large number of fuel channels - sets the most demanding requirements on the speed and reactivity depth of the shutdown system devices - shutoff rods and liquid poison injection. While the event is extremely improbable, it is reanalyzed periodically and its consequences examined to ensure continued shutdown system effectiveness. In March 1993, an additional effect was identified: if the break occurred in the piping on the inlet side of the core, this would cause sudden movement of the fuel bundles (so-called fuel string relocation) in a large number of channels. In Ontario Hydro`s Bruce NGS A, Bruce NGS B and Darlington reactors, each channel is fuelled against the flow. In this situation, the relocation of the fuel string results in a sudden positive reactivity increase. This reactivity increase is in addition to the reactivity due to the core coolant voiding. The combined reactivity effect could lead to power pulses much higher than those that would arise due to coolant voiding alone. To maintain safety margins in the event of such a postulated accident, the eight Bruce NGS A and Bruce NGS B units were initially derated to 60 percent power within 2 days of the identification and confirmation of this effect. This paper: describes the fuel string relocation phenomenon in detail; explains why the consequences differ at the various Ontario Hydro reactors; outlines the actions taken with respect to each of the Ontario Hydro reactors in the months following March 1993; describes the design solutions implemented to mitigate the problem and return the Bruce reactors to higher powers. 6 refs., 1 tab., 6 figs.
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
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
Type I supergravity effective action from pure spinor formalism
International Nuclear Information System (INIS)
Alencar, Geova
2009-01-01
Using the pure spinor formalism, we compute the tree-level correlation functions for three strings, one closed and two open, in N = 1 D = 10 superspace. Expanding the superfields in components, the respective terms of the effective action for the type I supergravity are obtained. All terms found agree with the effective action known in the literature. This result gives one more consistency test for the pure spinor formalism.
Dynamics of strings between walls
International Nuclear Information System (INIS)
Eto, Minoru; Fujimori, Toshiaki; Nagashima, Takayuki; Nitta, Muneto; Ohashi, Keisuke; Sakai, Norisuke
2009-01-01
Configurations of vortex strings stretched between or ending on domain walls were previously found to be 1/4 Bogomol'nyi-Prasad-Sommerfield (BPS) states in N=2 supersymmetric gauge theories in 3+1 dimensions. Among zero modes of string positions, the center of mass of strings in each region between two adjacent domain walls is shown to be non-normalizable whereas the rests are normalizable. We study dynamics of vortex strings stretched between separated domain walls by using two methods, the moduli space (geodesic) approximation of full 1/4 BPS states and the charged particle approximation for string end points in the wall effective action. In the first method we explicitly obtain the effective Lagrangian in the strong coupling limit, which is written in terms of hypergeometric functions, and find the 90 deg. scattering for head-on collision. In the second method the domain wall effective action is assumed to be U(1) N gauge theory, and we find a good agreement between two methods for well-separated strings.
The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings
Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat
2018-06-01
In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.
Effect of the cosmological constant on the deflection angle by a rotating cosmic string
Jusufi, Kimet; Övgün, Ali
2018-03-01
We report the effect of the cosmological constant and the internal energy density of a cosmic string on the deflection angle of light in the spacetime of a rotating cosmic string with internal structure. We first revisit the deflection angle by a rotating cosmic string and then provide a generalization using the geodesic equations and the Gauss-Bonnet theorem. We show there is an agreement between the two methods when employing higher-order terms of the linear mass density of the cosmic string. By modifying the integration domain for the global conical topology, we resolve the inconsistency between these two methods previously reported in the literature. We show that the deflection angle is not affected by the rotation of the cosmic string; however, the cosmological constant Λ strongly affects the deflection angle, which generalizes the well-known result.
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
Rotating black string and the effective Teukolsky equation in the braneworld
International Nuclear Information System (INIS)
Kanno, Sugumi; Soda, Jiro
2004-01-01
In the Randall-Sundrum two-brane (RS1) model, a large Kerr black hole on the brane can be naturally identified with a section of a rotating black string. To estimate Kaluza-Klein (KK) corrections on gravitational waves emitted by perturbed rotating black strings, we give the effective Teukolsky equation on the brane, which is a separable equation and hence numerically manageable. In this process, we derive the master equation for the electric part of the Weyl tensor, E μν , which is also useful in discussing the transition from black strings to localized black holes triggered by Gregory-Laflamme instability
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
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
Low-energy effective action for the superstring
International Nuclear Information System (INIS)
Burgess, C.P.; Font, A.; Quevedo, F.
1986-01-01
We construct the low-energy D=4, N=1 supergravity that arises in superstring theories for an arbitrary number of generations. The coupling of all massless modes that carry low-energy gauge quantum numbers are calculated by truncating the heavy Kaluza-Klein modes of the ten-dimensional effective field theory. The resulting action is compared to the most general effective action compatible with the symmetries of the underlying ten-dimensional field (and string) theories. This comparison indicates which features of the truncation correctly approximate the exact low-energy action. (orig.)
From UV/IR mixing to closed strings
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Lopez, Esperanza
2003-01-01
It was shown in [1] that the leading UV/IR mixing effects in noncommutative gauge theories on D-branes are able to capture information about the closed string spectrum of the parent string theory. The analysis was carried out for D-branes on nonsupersymmetric C 3 /Z N orbifolds of Type IIB. In this paper we consider D-branes on twisted circles compactifications of Type II string theory. We find that the signs of the leading UV/IR mixing effects know about the (mass) 2 gap between the lowest modes in NSNS and RR closed string towers. Moreover, the relevant piece of the field theory effective action can be reproduced purely in the language of closed strings. Remarkably, this approach unifies in a single structure, that of a closed string exchange between D-branes, both the leading planar and nonplanar effects associated to the absence of supersymmetry. (author)
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Kalashnikova, Yu.S.; Nefediev, A.V.
1997-01-01
The QCD-motivated constituent string model is extended to consider the baryon. The system of three quarks propagating in the confining background field is studied in the Wilson loop approach, and the effective action is obtained. The resulting Lagrangian at large interquark distances corresponds to the Mercedes Benz string configuration. Assuming the quarks to be heavy enough to allow the adiabatic separation of quark and string junction motion and using the hyperspherical expansion for the quark subsystem we write out and solve the classical equation of motion for the junction. We quantize the motion of the junction and demonstrate that the account of these modes leads to the effective swelling of baryon in comparison with standard potential picture. The effects of finite gluonic correlation length which do not affect the excited states but appear to be substantial for the baryonic ground state, reducing the swelling considerably is discussed
Stiff self-interacting strings at high temperature QCD
S Bakry, A.; Chen, X.; Deliyergiyev, M.; Galal, A.; Khalaf, A.; M Pengming, P.
2018-03-01
We investigate the implications of Nambu-Goto (NG), Lüscher Weisz (LW) and Polyakov-Kleinert (PK) effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3) Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO) contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.
Non-renormalisation theorems in string theory
International Nuclear Information System (INIS)
Vanhove, P.
2007-10-01
In this thesis we describe various non renormalisation theorems for the string effective action. These results are derived in the context of the M theory conjecture allowing to connect the four gravitons string theory S matrix elements with that of eleven dimensional supergravity. These theorems imply that N = 8 supergravity theory has the same UV behaviour as the N = 4 supersymmetric Yang Mills theory at least up to three loops, and could be UV finite in four dimensions. (author)
Heart strings and purse strings: Carryover effects of emotions on economic decisions.
Lerner, Jennifer S; Small, Deborah A; Loewenstein, George
2004-05-01
We examined the impact of specific emotions on the endowment effect, the tendency for selling prices to exceed buying or "choice" prices for the same object. As predicted by appraisal-tendency theory, disgust induced by a prior, irrelevant situation carried over to normatively unrelated economic decisions, reducing selling and choice prices and eliminating the endowment effect. Sadness also carried over, reducing selling prices but increasing choice prices--producing a "reverse endowment effect" in which choice prices exceeded selling prices. The results demonstrate that incidental emotions can influence decisions even when real money is at stake, and that emotions of the same valence can have opposing effects on such decisions.
Real topological string amplitudes
Energy Technology Data Exchange (ETDEWEB)
Narain, K.S. [The Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, Trieste, 34151 (Italy); Piazzalunga, N. [Simons Center for Geometry and Physics, State University of New York,Stony Brook, NY, 11794-3636 (United States); International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy); Tanzini, A. [International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy)
2017-03-15
We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G{sub χ}, at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g{sup ′}=−χ+1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F{sub g}.
Noncompact symmetries in string theory
International Nuclear Information System (INIS)
Maharana, J.; Schwarz, J.H.
1993-01-01
Noncompact groups, similar to those that appeared in various supergravity theories in the 1970's have been turning up in recent studies of string theory. First it was discovered that moduli spaces of toroidal compactification are given by noncompact groups modded out by their maximal compact subgroups and discrete duality groups. Then it was found that many other moduli spaces have analogous descriptions. More recently, noncompact group symmetries have turned up in effective actions used to study string cosmology and other classical configurations. This paper explores these noncompact groups in the case of toroidal compactification both from the viewpoint of low-energy effective field theory, using the method of dimensional reduction, and from the viewpoint of the string theory world-sheet. The conclusion is that all these symmetries are intimately related. In particular, we find that Chern-Simons terms in the three-form field strength H μνρ play a crucial role. (orig.)
String-theoretic breakdown of effective field theory near black hole horizons
Dodelson, Matthew; Silverstein, Eva
2017-09-01
We investigate the validity of the equivalence principle near horizons in string theory, analyzing the breakdown of effective field theory caused by longitudinal string spreading effects. An experiment is set up where a detector is thrown into a black hole a long time after an early infalling string. Light cone gauge calculations, taken at face value, indicate a detectable level of root-mean-square longitudinal spreading of the initial string as measured by the late infaller. This results from the large relative boost between the string and detector in the near-horizon region, which develops automatically despite their modest initial energies outside the black hole and the weak curvature in the geometry. We subject this scenario to basic consistency checks, using these to obtain a relatively conservative criterion for its detectability. In a companion paper, we exhibit longitudinal nonlocality in well-defined gauge-invariant S-matrix calculations, obtaining results consistent with the predicted spreading albeit not in a direct analog of the black hole process. We discuss applications of this effect to the firewall paradox, and estimate the time and distance scales it predicts for new physics near black hole and cosmological horizons.
Finite size effects for giant magnons on physical strings
International Nuclear Information System (INIS)
Minahan, J.A.; Ohlsson Sax, O.
2008-01-01
Using finite gap methods, we find the leading order finite size corrections for an arbitrary number of giant magnons on physical strings, where the sum of the momenta is a multiple of 2π. Our results are valid for the Hofman-Maldacena fundamental giant magnons as well as their dyonic generalizations. The energy corrections turn out to be surprisingly simple, especially if all the magnons are fundamental, and at leading order are independent of the magnon flavors. We also show how to use the Bethe ansatz to find finite size corrections for dyonic giant magnons with large R-charges
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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.)
Nambu-Goto string with the Gauss-Bonnet term and point-like masses at the ends
Hadasz, Leszek; Róg, Tomasz
1996-02-01
We investigate classical dynamics of the Nambu-Goto string with Gauss-Bonnet term in the action and point-like masses at the ends in the context of effective QCD string. The configuration of rigidly rotating string is studied and its application to phenomenological description of meson spectroscopy is discussed.
The Effect of String Tension Variation on the Perceived Pitch of a Classical Guitar
Directory of Open Access Journals (Sweden)
Wanda Jadwiga Lewis
2014-09-01
Full Text Available Actual motion of a vibrating guitar string is a superposition of many possible shapes (modes in which it could vibrate. Each of these modes has a corresponding frequency, and the lowest frequency is associated with a shape idealised as a single wave, referred to as the fundamental mode. The other contributing modes, each with their own progressively higher frequency, are referred to as overtones, or harmonics. By attaching a string to a medium (a soundboard capable of a response to the vibrating string, sound waves are generated. The sound heard is dominated by the fundamental mode, ‘coloured’ by contributions from the overtones, as explained by the classical theory of vibration. The classical theory, however, assumes that the string tension remains constant during vibration, and this cannot be strictly true; when considering just the fundamental mode, string tension will reach two maximum changes, as it oscillates up and down. These changes, occurring twice during the fundamental period match the frequency of the octave higher, 1st overtone. It is therefore plausible to think that the changing tension effect, through increased force on the bridge and, therefore, greater soundboard deflection, could be amplifying the colouring effect of (at least the 1st overtone. In this paper, we examine the possible influence of string tension variation on tonal response of a classical guitar. We use a perturbation model based on the classical result for a string in general vibration in conjunction with a novel method of assessment of plucking force that incorporates the engineering concept of geometric stiffness, to assess the magnitude of the normal force exerted by the string on the bridge. The results of our model show that the effect of tension variation is significantly smaller than that due to the installed initial static tension, and affects predominantly the force contribution arising from the fundamental mode. We, therefore, conclude that string
Incompatibility of torsion with the Gauss-Bonnet combination in the bosonic string
International Nuclear Information System (INIS)
Bern, Z.; Shimada, T.; Hochberg, D.
1987-01-01
In general, either manifest unitarity or the inclusion of the antisymmetric tensor field strength as torsion can be trivially implemented via field redefinitions in string theory low energy effective actions. However, requiring both simultaneously is explicitly shown to be incompatible in the bosonic string effective action. We also discuss the usefulness of the redefinition theorem as a technical tool. (orig.)
Unusual motions due to nonlinear effects in a driven vibrating string
Hanson, Roger J.
2005-09-01
Usual nonlinear effects observed in a sinusoidally driven vibrating string include generation of motion perpendicular to the driving plane, sudden jumps of amplitude and associated hysteresis, and generation of higher harmonics. In addition, under some conditions, there can be a rich variety of unusual, very complex motions of a point on the string, the pattern of which, together with associated harmonic (and sometimes subharmonic) content, can change dramatically with a slight change in driving frequency or sometimes with constant driving frequency and force. Intrinsic string asymmetries can also have a profound effect on the behavior. In a brass harpsichord string (wire) such asymmetries can cause a small splitting of each natural frequency of free vibration into two closely spaced frequencies (relative separation ~0.2% to 2%, strongly dependent on tension.) The two frequency components are associated, respectively, with the transverse motion along two orthogonal characteristic wire axes. Emphasis will be on display of optically detected unusual motion patterns of a point on the string, including an example of a pattern period of 10 s when driving at 50 Hz. See R. J. Hanson et al., J. Acoust. Soc. Am. 117, 400-412 (2005) for a more complete treatment.
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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.
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
Fluctuations of the baryonic flux-tube junction from effective string theory
International Nuclear Information System (INIS)
Pfeuffer, Melanie; Bali, Gunnar S.; Panero, Marco
2009-01-01
In quenched QCD, where the dynamic creation of quark-antiquark pairs out of the vacuum is neglected, a confined baryonic system composed of three static quarks exhibits stringlike behavior at large interquark separation, with the formation of flux tubes characterized by the geometry of the so-called Y ansatz. We study the fluctuations of the junction of the three flux tubes, assuming the dynamics to be governed by an effective bosonic string model. We show that the asymptotic behavior of the effective width of the junction grows logarithmically with the distance between the sources, with the coefficient depending on the number of joining strings, on the dimension of spacetime and on the string tension.
International Nuclear Information System (INIS)
Ketov, S.V.
1996-09-01
Taking the (2,2) strings as a starting point, we discuss the equivalent self-dual field theories and analyze their symmetry structure in 2+2 dimensions from the viewpoint of string/membrane unification. Requiring the 'Lorentz' invariance and supersymmetry in the (2,2) string target space leads to an extension of the (2,2) string theory to a theory of 2+2 dimensional supermembranes (M-branes) propagating in a higher dimensional target space. The origin of the hidden target space dimensions of the M-brane is related to the maximally extended supersymmetry implied by the 'Lorentz' covariance and dimensional reasons. The Kaehler-Chern-Simons-type action describing the self-dual gravity in 2+2 dimensions is proposed. Its maximal supersymmetrization (of the Green-Schwarz-type) naturally leads to the 2+10 (or higher) dimensions for the M-brane target space. The proposed OSp(32 vertical stroke 1) supersymmetric action gives the pre-geometrical description of M-branes, which may be useful for a fundamental formulation of F and M theory. (orig.)
Effective action and brane running
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Brevik, Iver; Ghoroku, Kazuo; Yahiro, Masanobu
2004-01-01
We address the renormalized effective action for a Randall-Sundrum brane running in 5D bulk space. The running behavior of the brane action is obtained by shifting the brane position without changing the background and fluctuations. After an appropriate renormalization, we obtain an effective, low energy brane world action, in which the effective 4D Planck mass is independent of the running position. We address some implications for this effective action
Boundary effects relevant for the string interpretation of σ-models
International Nuclear Information System (INIS)
Behrndt, K.; Dorn, H.
1991-01-01
At first a short discussion of the on/off boundary position dependence of the renormalization counter terms and β-functions for generalized σ-models on manifolds with boundary is given. Treating the energy-momentum tensor of such models as a two-dimensional distribution one can show that contrary to the first impression this does not imply any obstruction for the string interpretation of such models. The analysis is extended to the effect of dual loop corrections to string induced equations of motion, too. (orig.)
Background Independent Open String Field Theory and Constant B-Field
Nemeschansky, D.; Yasnov, V.
2000-01-01
We calculate the background independent action for bosonic and supersymmetric open string field theory in a constant B-field. We also determine the tachyon effective action in the presence of constant B-field.
Probing the string winding sector
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Aldazabal, Gerardo; Mayo, Martín [G. Física CAB-CNEA and CONICET, Centro Atómico Bariloche,Av. Bustillo 9500, Bariloche (Argentina); Instituto Balseiro, Centro Atómico Bariloche,Av. Bustillo 9500, Bariloche (Argentina); Nuñez, Carmen [Instituto de Astronomía y Física del Espacio (CONICET-UBA),C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, FCEN, Universidad de Buenos Aires,C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina)
2017-03-17
We probe a slice of the massive winding sector of bosonic string theory from toroidal compactifications of Double Field Theory (DFT). This string subsector corresponds to states containing one left and one right moving oscillators. We perform a generalized Kaluza Klein compactification of DFT on generic 2n-dimensional toroidal constant backgrounds and show that, up to third order in fluctuations, the theory coincides with the corresponding effective theory of the bosonic string compactified on n-dimensional toroidal constant backgrounds, obtained from three-point amplitudes. The comparison between both theories is facilitated by noticing that generalized diffeomorphisms in DFT allow to fix generalized harmonic gauge conditions that help in identifying the physical degrees of freedom. These conditions manifest as conformal anomaly cancellation requirements on the string theory side. The explicit expression for the gauge invariant effective action containing the physical massless sector (gravity+antisymmetric+gauge+ scalar fields) coupled to towers of generalized Kaluza Klein massive states (corresponding to compact momentum and winding modes) is found. The action acquires a very compact form when written in terms of fields carrying O(n,n) indices, and is explicitly T-duality invariant. The global algebra associated to the generalized Kaluza Klein compactification is discussed.
Chern-Simons couplings for dielectric F-strings in matrix string theory
International Nuclear Information System (INIS)
Brecher, Dominic; Janssen, Bert; Lozano, Yolanda
2002-01-01
We compute the non-abelian couplings in the Chern-Simons action for a set of coinciding fundamental strings in both the type IIA and type IIB Matrix string theories. Starting from Matrix theory in a weakly curved background, we construct the linear couplings of closed string fields to type IIA Matrix strings. Further dualities give a type IIB Matrix string theory and a type IIA theory of Matrix strings with winding. (Abstract Copyright[2002], Wiley Periodicals, Inc.)
Regularized strings with extrinsic curvature
International Nuclear Information System (INIS)
Ambjoern, J.; Durhuus, B.
1987-07-01
We analyze models of discretized string theories, where the path integral over world sheet variables is regularized by summing over triangulated surfaces. The inclusion of curvature in the action is a necessity for the scaling of the string tension. We discuss the physical properties of models with extrinsic curvature terms in the action and show that the string tension vanishes at the critical point where the bare extrinsic curvature coupling tends to infinity. Similar results are derived for models with intrinsic curvature. (orig.)
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
International Nuclear Information System (INIS)
Nandi, K.K.; Zhang Yuanzhong
2004-01-01
Three new classes (II-IV) of solutions of the vacuum low energy effective string theory in four dimensions are derived. Wormhole solutions are investigated in those solutions including the class I case both in the Einstein and in the Jordan (string) frame. It turns out that, of the eight classes of solutions investigated (four in the Einstein frame and four in the corresponding string frame), massive Lorentzian traversable wormholes exist in five classes. Nontrivial massless limit exists only in class I Einstein frame solution while none at all exists in the string frame. An investigation of test scalar charge motion in the class I solution in the two frames is carried out by using the Plebanski-Sawicki theorem. A curious consequence is that the motion around the extremal zero (Keplerian) mass configuration leads, as a result of scalar-scalar interaction, to a new hypothetical 'mass' that confines test scalar charges in bound orbits, but does not interact with neutral test particles
Proper acceleration, the geometric tachyon and the dynamics of a fundamental string near Dp branes
International Nuclear Information System (INIS)
Das, Ashok; Panda, Sudhakar; Roy, Shibaji
2009-01-01
We present a detailed analysis of our recent observation that the origin of the geometric tachyon, which arises when a Dp brane propagates in the vicinity of a stack of coincident NS5 branes, is due to the proper acceleration generated by the background dilaton field. We show that when a fundamental string (F-string), described by the Nambu-Goto action, is moving in the background of a stack of coincident Dp branes, the geometric tachyon mode can also appear since the overall conformal mode of the induced metric for the string can act as a source for proper acceleration. We also studied the detailed dynamics of the F-string as well as the instability by mapping the Nambu-Goto action of the F-string to the tachyon effective action of the non-BPS D-string. We qualitatively argue that the condensation of the geometric tachyon is responsible for the (F,Dp) bound state formation.
Geometric low-energy effective action in a doubled spacetime
Ma, Chen-Te; Pezzella, Franco
2018-05-01
The ten-dimensional supergravity theory is a geometric low-energy effective theory and the equations of motion for its fields can be obtained from string theory by computing β functions. With d compact dimensions, an O (d , d ; Z) geometric structure can be added to it giving the supergravity theory with T-duality manifest. In this paper, this is constructed through the use of a suitable star product whose role is the one to implement the weak constraint on the fields and the gauge parameters in order to have a closed gauge symmetry algebra. The consistency of the action here proposed is based on the orthogonality of the momenta associated with fields in their triple star products in the cubic terms defined for d ≥ 1. This orthogonality holds also for an arbitrary number of star products of fields for d = 1. Finally, we extend our analysis to the double sigma model, non-commutative geometry and open string theory.
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.)
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
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)
Bergman, Ramona; Andersson-Sköld, Yvonne; Nyberg, Lars; Johansson, Magnus
2010-05-01
In a project funded by the Swedish Civil Contingencies Agency, the effort and work to reduce different kinds of accidents are being evaluated. The project wants to illuminate the links between actions and outcome, so we can learn from today's performance and in the future select more effective measures and overall deal with accidents more efficiently. The project ESS covers the field of frequent accidents such as sliding accidents at home, in house fires and less common accidents such as chemical and land fill accidents up to even more rare accidents such as natural accidents and hazards. In the ESS project SGI (Swedish geotechnical institute) will evaluate the work and effort concerning various natural hazards limited to landslides, erosion and flooding. The aim is to investigate how municipalities handle, especially prevention, of such natural disasters today. The project includes several aspects such as: • which are the driving forces for risk analysis in a municipality • do one use risk mapping (and what type) in municipal risk analysis • which aspects are most important when selecting preventive measures • in which way do one learn from past accidents • and from previous accidents elsewhere, by for example use existing databases • etc There are many aspects that play a role in a well-functioning safety promotion work. The overall goal is to examine present work and activities, highlight what is well functioning and identify weak points. The aim is to find out where more resources are needed and give suggestions for a more efficient security work. This includes identification of the most efficient "tools" in use or needed. Such tools can be education, directives, funding, more easily available maps and information regarding previous accidents and preventive measures etc. The project will result in recommendations for more effective ways to deal with landslides, erosion and flooding. Since different kinds of problems can occur depending on level of
International Nuclear Information System (INIS)
Esmaeilzadeh Khadem, S.; Rezaee, M.
2001-01-01
In this paper the large amplitude and non-linear vibration of a string is considered. The initial tension, lateral vibration amplitude, diameter and the modulus of elasticity of the string have main effects on its natural frequencies. Increasing the lateral vibration amplitude makes the assumption of constant initial tension invalid. In this case, therefore, it is impossible to use the classical equation of string with small amplitude transverse motion assumption. On the other hand, by increasing the string diameter, the bending moment effect will increase dramatically, and acts as an impressive restoring moment. Considering the effects of the bending moments, the nonlinear equation governing the large amplitude transverse vibration of a string is derived. The time dependent portion of the governing equation has the from of Duff ing equation is solved using the perturbation theory. The results of the analysis are shown in appropriate graphs, and the natural frequencies of the string due to the non-linear factors are compared with the natural frequencies of the linear vibration os a string without bending moment effects
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.)
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.)
Energy Technology Data Exchange (ETDEWEB)
Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa-PB (Brazil); Furtado, C., E-mail: furtado@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa-PB (Brazil); Belich, H., E-mail: belichjr@gmail.com [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)
2016-09-15
From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov–Casher geometric quantum phase in the nonrelativistic limit.
Topological amplitudes in string theory
International Nuclear Information System (INIS)
Antoniadis, I.; Taylor, T.R.
1993-07-01
We show that certain type II string amplitudes at genus g are given by the topological partition F g discussed recently by Bershadsky, Cecotti, Ooguri and Vafa. These amplitudes give rise to a term in the four-dimensional effective action of the form Σ g F g W 2g , where W is the chiral superfield of N = 2 supergravitational multiplet. The holomorphic anomaly of F g is related to non-localities of the effective action due to the propagation of massless states. This result generalizes the holomorphic anomaly of the one loop case which is known to lead to non-harmonic gravitational couplings. (author). 22 refs, 2 figs
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
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.)
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.
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.
Supersymmetric closed string tachyon cosmology: a first approach
International Nuclear Information System (INIS)
Vázquez-Báez, V; Ramírez, C
2014-01-01
We give a worldline supersymmetric formulation for the effective action of closed string tachyon in a FRW background. This is done considering that, as shown by Vafa, the effective theory of closed string tachyons can have worldsheet supersymmetry. The Hamiltonian is constructed by means of the Dirac procedure and written in a quantum version. By using the supersymmetry algebra we are able to find solutions to the Wheeler-DeWitt equation via a more simple set of first order differential equations
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
Cosmic strings and galaxy formation
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.
International Nuclear Information System (INIS)
Rowland, David R
2013-01-01
Introductory discussions of energy transport due to transverse waves on taut strings universally assume that the effects of longitudinal motion can be neglected, but this assumption is not even approximately valid unless the string is idealized to have a zero relaxed length, a requirement approximately met by the slinky spring. While making this additional idealization is probably the best approach to take when discussing waves on strings at the introductory level, for intermediate to advanced undergraduate classes in continuum mechanics and general wave phenomena where somewhat more realistic models of strings can be investigated, this paper makes the following contributions. First, various approaches to deriving the general energy continuity equation are critiqued and it is argued that the standard continuum mechanics approach to deriving such equations is the best because it leads to a conceptually clear, relatively simple derivation which provides a unique answer of greatest generality. In addition, a straightforward algorithm for calculating the transverse and longitudinal waves generated when a string is driven at one end is presented and used to investigate a cos 2 transverse pulse. This example illustrates much important physics regarding energy transport in strings and allows the ‘attack waves’ observed when strings in musical instruments are struck or plucked to be approximately modelled and analysed algebraically. Regarding the ongoing debate as to whether the potential energy density in a string can be uniquely defined, it is shown by coupling an external energy source to a string that a suggested alternative formula for potential energy density requires an unphysical potential energy to be ascribed to the source for overall energy to be conserved and so cannot be considered to be physically valid. (paper)
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.)
Scalar bosons under the influence of noninertial effects in the cosmic string spacetime
Energy Technology Data Exchange (ETDEWEB)
Santos, L.C.N.; Barros, C.C. [Universidade Federal de Santa Catarina, Dept. de Fisica, CFM, Florianopolis, SC (Brazil)
2017-03-15
In this paper we present two different classes of solutions for the Klein-Gordon equation in the presence of a scalar potential under the influence of noninertial effects in the cosmic string spacetime. We show that noninertial effects restrict the physical region of the spacetime where the particle can be placed, and furthermore that the energy levels are shifted by these effects. In addition, we show that the presence of a Coulomb-like scalar potential allows the formation of bound states when the Klein-Gordon equation is considered in this kind of spacetime. (orig.)
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.
From maximal to minimal supersymmetry in string loop amplitudes
Energy Technology Data Exchange (ETDEWEB)
Berg, Marcus; Buchberger, Igor [Department of Physics, Karlstad University,651 88 Karlstad (Sweden); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,14476 Potsdam (Germany)
2017-04-28
We calculate one-loop string amplitudes of open and closed strings with N=1,2,4 supersymmetry in four and six dimensions, by compactification on Calabi-Yau and K3 orbifolds. In particular, we develop a method to combine contributions from all spin structures for arbitrary number of legs at minimal supersymmetry. Each amplitude is cast into a compact form by reorganizing the kinematic building blocks and casting the worldsheet integrals in a basis. Infrared regularization plays an important role to exhibit the expected factorization limits. We comment on implications for the one-loop string effective action.
The tachyon potential in string theory
International Nuclear Information System (INIS)
Banks, T.
1991-01-01
We argue that the tachyon potential in string theory is exactly given by the unstable quadratic mass term calculated perturbatively around the critical string. The argument is given in terms of the sigma model formulation. The same result follows from the exact Wilson renormalization group equations. The discrepancy with previous calculations of the tachyon potential is explained by the fact that other authors worked near the tachyon mass shell where it is impossible to distinguish a potential from derivative terms in the effective action. (orig.)
String effects on Fermi-Dirac correlation measurements
International Nuclear Information System (INIS)
Duran Delgado, R.M.; Gustafson, G.; Loennblad, L.
2007-01-01
We investigate some recent measurements of Fermi-Dirac correlations by the LEP collaborations indicating surprisingly small source radii for the production of baryons in e + e - annihilation at the Z 0 peak. In hadronization models there is besides the Fermi-Dirac correlation effect also a strong dynamical (anti-) correlation. We demonstrate that the extraction of the pure FD effect is highly dependent on a realistic Monte Carlo event generator, both for separation of those dynamical correlations that are not related to Fermi-Dirac statistics, and for corrections of the data and background subtractions. Although the model can be tuned to well reproduce single particle distributions, there are large model uncertainties when it comes to correlations between identical baryons. We therefore, unfortunately, have to conclude that it is at present not possible to draw any firm conclusion about the source radii relevant for baryon production at LEP. (orig.)
Effect of extra dimensions on gravitational waves from cosmic strings.
O'Callaghan, Eimear; Chadburn, Sarah; Geshnizjani, Ghazal; Gregory, Ruth; Zavala, Ivonne
2010-08-20
We show how the motion of cosmic superstrings in extra dimensions can modify the gravitational wave signal from cusps. Additional dimensions both round off cusps, as well as reducing the probability of their formation, and thus give a significant dimension dependent damping of the gravitational waves. We look at the implication of this effect for LIGO and LISA, as well as commenting on more general frequency bands.
Gauge invariance of string fields
International Nuclear Information System (INIS)
Banks, T.; Peskin, M.E.
1985-10-01
Some work done to understand the appearance of gauge bosons and gravitons in string theories is reported. An action has been constructed for free (bosonic) string field theory which is invariant under an infinite set of gauge transformations which include Yang-Mills transformations and general coordinate transformations as special cases. 15 refs., 1 tab
Introduction to bosonic string theory
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Nunez, Carmen [Instituto de Astronomia y Fisica del Espacio, Buenos Aires (Argentina)], e-mail: carmen@iafe.uba.ar
2009-07-01
This is an introductory set of five lectures on bosonic string theory. The first one deals with the classical theory of bosonic strings. The second and third lectures cover quantization. Three basic quantization methods are sketched: the old covariant formalism, the light-cone gauge quantization, where the spectrum is derived and the Polyakov path integral formalism and in particular the partition function at one loop. Finally, the last lecture covers interactions, low energy effective action, the general idea of compactification and in particular toroidal compactification. The notes are based on books by Green, Schwarz and Witten, Polchinski, Lust and Theissen and Kaku and review papers by D'Hocker and Phong and O. Alvarez. (author)
Two field formulation of closed string field theory
International Nuclear Information System (INIS)
Bogojevic, A.R.
1990-09-01
A formulation of closed string field theory is presented that is based on a two field action. It represents a generalization of Witten's Chern-Simons formulation of 3d gravity. The action contains only 3 string interactions and no string field truncations, unlike the previous non-polynomial action of Zwiebach. The two field action is found to follow from a purely cubic, background independent action similar to the one for open strings. (orig.)
Gholibeigian, Hassan; Amirshahkarami, Abdolazim; Gholibeigian, Kazem
2017-01-01
In special relativity theory, time dilates in velocity of near light speed. Also based on ``Substantial motion'' theory of Sadra, relative time (time flux); R = f (mv , σ , τ) , for each atom is momentum of its involved fundamental particles, which is different from the other atoms. In this way, for modification of the relativistic classical equation of string theory and getting more precise results, we should use effect of dilation and contraction of time in equation. So we propose to add two derivatives of the time's flux to the equation as follows: n.tp∂/R ∂ τ +∂2Xμ/(σ , τ) ∂τ2 = n .tp (∂/R ∂ σ ) +c2∂2Xμ/(σ , τ) ∂σ2 In which, Xμ is space-time coordinates of the string, σ & τ are coordinates on the string world sheet, respectively space and time along the string, string's mass m , velocity of string's motion v , factor n depends on geometry of each hidden extra dimension which relates to its own flux time, and tp is Planck's time. AmirKabir University of Technology, Tehran, Iran.
General relativity invariance and string field theory
International Nuclear Information System (INIS)
Aref'eva, I.Ya.; Volovich, I.V.
1987-04-01
The general covariance principle in the string field theory is considered. The algebraic properties of the string Lie derivative are discussed. The string vielbein and spin connection are introduced and an action invariant under general co-ordinate transformation is proposed. (author). 18 refs
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.
Single spin asymmetry in inclusive pion production, Collins effect and the string model
International Nuclear Information System (INIS)
Artru, X.; Czyzewski, J.; Yabuki, H.
1994-05-01
We calculate the single spin asymmetry in the inclusive pion production in proton-proton collisions. We generate the asymmetry at the level of fragmentation function (Collins effect) by the Lund coloured string mechanism. We compare our results with the Fermilab E704 data from p ↑p collisions at 200 GeV. We show that the transversely polarized quark densities at high Bjorken x strongly differ from these predicted by the SU(6) proton wave function. (authors). 18 refs., 7 figs
Effect of detector size and position on measured vibration spectra of strings and rods
International Nuclear Information System (INIS)
Lipcsei, S.; Kiss, S.; Por, G.
1993-04-01
Weight functions of string and rod vibrations are described by standing and travelling wave models. The effects of detector size and position on the measured vibration spectra was investigated, and the main characteristics of the transfer function were calculated by a simple standing wave model. The theoretical results were compared with data from laboratory rod vibration experiments, and with pressure fluctuation spectra obtained at the Paks Nuclear Power Plant. In addition, some fundamental physical consequences can be made using the theory of superposition of travelling waves and their reflection on clamped rod ends. (R.P.) 5 refs.; 10 figs
Closed flux tubes in D=2+1SU(N) gauge theories: dynamics and effective string description
International Nuclear Information System (INIS)
Athenodorou, Andreas; Teper, Michael
2016-01-01
We extend our earlier calculations of the spectrum of closed flux tubes in SU(N) gauge theories in 2+1 dimensions, with a focus on questions raised by recent theoretical progress on the effective string action of long flux tubes and the world-sheet action for flux tubes of moderate lengths. Our new calculations in SU(4) and SU(8) provide evidence that the leading O(1/l"γ) non-universal correction to the flux tube ground state energy does indeed have a power γ≥7. We perform a study in SU(2), where we can traverse the length at which the Nambu-Goto ground state becomes tachyonic, to obtain an all-N view of the spectrum. Our comparison of the k=2 flux tube excitation energies in SU(4) and SU(6) suggests that the massive world sheet excitation associated with the k=2 binding has a scale that knows about the group and hence the theory in the bulk, and we comment on the potential implications of world sheet massive modes for the bulk spectrum. We provide a quantitative analysis of the surprising (near-)orthogonality of flux tubes carrying flux in different SU(N) representations, which implies that their screening by gluons is highly suppressed even at small N.
Closed flux tubes in D=2+1SU(N) gauge theories: dynamics and effective string description
Energy Technology Data Exchange (ETDEWEB)
Athenodorou, Andreas [Department of Physics, University of Cyprus,POB 20537, 1678 Nicosia (Cyprus); Computation-based Science and Technology Research Center, The Cyprus Institute,20 Kavafi Str., Nicosia 2121 (Cyprus); Teper, Michael [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom)
2016-10-18
We extend our earlier calculations of the spectrum of closed flux tubes in SU(N) gauge theories in 2+1 dimensions, with a focus on questions raised by recent theoretical progress on the effective string action of long flux tubes and the world-sheet action for flux tubes of moderate lengths. Our new calculations in SU(4) and SU(8) provide evidence that the leading O(1/l{sup γ}) non-universal correction to the flux tube ground state energy does indeed have a power γ≥7. We perform a study in SU(2), where we can traverse the length at which the Nambu-Goto ground state becomes tachyonic, to obtain an all-N view of the spectrum. Our comparison of the k=2 flux tube excitation energies in SU(4) and SU(6) suggests that the massive world sheet excitation associated with the k=2 binding has a scale that knows about the group and hence the theory in the bulk, and we comment on the potential implications of world sheet massive modes for the bulk spectrum. We provide a quantitative analysis of the surprising (near-)orthogonality of flux tubes carrying flux in different SU(N) representations, which implies that their screening by gluons is highly suppressed even at small N.
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.)
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
Diaz, Victor Alfonzo; Giusti, Andrea
2018-03-01
The aim of this paper is to present a simple generalization of bosonic string theory in the framework of the theory of fractional variational problems. Specifically, we present a fractional extension of the Polyakov action, for which we compute the general form of the equations of motion and discuss the connection between the new fractional action and a generalization the Nambu-Goto action. Consequently, we analyze the symmetries of the modified Polyakov action and try to fix the gauge, following the classical procedures. Then we solve the equations of motion in a simplified setting. Finally, we present a Hamiltonian description of the classical fractional bosonic string and introduce the fractional light-cone gauge. It is important to remark that, throughout the whole paper, we thoroughly discuss how to recover the known results as an "integer" limit of the presented model.
International Nuclear Information System (INIS)
Ahmed, I.; Chow, H.C.; Younis, M.H.
1996-01-01
An investigation aimed at determining the effect of fuel string relocation on reactivity excursion and power pulse following a hypothetical Large Break Loss of Coolant Accident in KANUPP reactor is reported. The assessment of reactivity insertion was performed making use of global (reactor) core analysis computer code RFSP. The reactor kinetics module CERBERUS of the RFSP code and the SOPHT (thermal-hydraulics code) were subsequently employed for the neutronic transient analysis. The effect was evaluated in context of determining the adequacy of moderator dump shutdown system. Because of the presence of the gap between the inlet shield plug and the fuel string, the fuel bundles may shift in such a manner that low-irradiated fuel is moved towards the core centre. This represents an additional reactivity increase to be accounted for in the analysis. The reactivity excursion, however, is alleviated by an earlier reactor trip. The net impact is that the energy deposited in the maximum rated fuel pencil is increased from 56% of the 960 kJ/kg fuel-centre-line melting limit to 63%. The result demonstrated the adequacy of the shutdown system against the maximum credible accident event. (author)
A new approach to the study of effective string corrections in LGTs
International Nuclear Information System (INIS)
Caselle, M.; Zago, M.
2011-01-01
We propose a new approach to the study of the interquark potential in Lattice Gauge Theories. Instead of looking at the expectation value of Polyakov loop correlators we study the modifications induced in the chromoelectric flux by the presence of the Polyakov loops. In abelian LGTs, thanks to duality, this study can be performed in a very efficient way, allowing to reach high precision at a reasonable CPU cost. The major advantage of this strategy is that it allows us to eliminate the dominant effective string correction to the interquark potential (the Luescher term) thus giving an unique opportunity to test higher order corrections. Performing a set of simulations in the 3d spin Ising model and then translating the result in the 3d gauge Ising model using duality, we were thus able to precisely identify and measure both the quartic and the sextic effective string corrections to the interquark potential. While the quartic term perfectly agrees with the Nambu-Goto one the sextic term is definitely different. Our result seems to disagree with the recent proof of the universality of the sextic correction. We discuss a few possible explanations of this disagreement. (orig.)
A new approach to the study of effective string corrections in LGTs
Energy Technology Data Exchange (ETDEWEB)
Caselle, M.; Zago, M. [Dipartimento di Fisica Teorica, Universita di Torino (Italy); I.N.F.N., Torino (Italy)
2011-05-15
We propose a new approach to the study of the interquark potential in Lattice Gauge Theories. Instead of looking at the expectation value of Polyakov loop correlators we study the modifications induced in the chromoelectric flux by the presence of the Polyakov loops. In abelian LGTs, thanks to duality, this study can be performed in a very efficient way, allowing to reach high precision at a reasonable CPU cost. The major advantage of this strategy is that it allows us to eliminate the dominant effective string correction to the interquark potential (the Luescher term) thus giving an unique opportunity to test higher order corrections. Performing a set of simulations in the 3d spin Ising model and then translating the result in the 3d gauge Ising model using duality, we were thus able to precisely identify and measure both the quartic and the sextic effective string corrections to the interquark potential. While the quartic term perfectly agrees with the Nambu-Goto one the sextic term is definitely different. Our result seems to disagree with the recent proof of the universality of the sextic correction. We discuss a few possible explanations of this disagreement. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Santos, L.C.N.; Barros, C.C. [Universidade Federal de Santa Catarina, Dept. de Fisica - CFM, Florianopolis, SC (Brazil)
2018-01-15
We study solutions for the Klein-Gordon equation with vector and scalar potentials of the Coulomb types under the influence of noninertial effects in the cosmic string spacetime. We also investigate a quantum particle described by the Klein-Gordon oscillator in the background spacetime generated by a cosmic string. An important result obtained is that the noninertial effects restrict the physical region of the spacetime where the particle can be placed. In addition, we show that these potentials can form bound states for the Klein-Gordon equation in this kind of background. (orig.)
International Nuclear Information System (INIS)
Shul'ga, N.F.; Truten', V.I.
1999-01-01
It is shown that a considerable decrease in a total cross-section of the elastic scattering of relativistic electrons by a crystal atomic string can take place at certain values of particle incidence angles. This effect is similar to the Ramsauer-Townsend effect of slow electrons scattering by an atom. It is shown that the decrease in the angle of particles incidence on the atomic string essentially changes the process of particles scattering. The phenomena of the particle rainbow scattering and orbiting may occur in this case. 14 refs., 5 figs
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
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
International Nuclear Information System (INIS)
Lugovoj, V.V.
1998-01-01
At proton-(anti) proton scattering in the frame of two-string Dual Parton Model the semihard parton-parton interactions can lead to the valence (anti) (di) quark excitations which lead to the production of up to four fast hadron leaders, and the process of soft colour interaction between constituents leads to formation of two primary strings, which decay into secondary hadrons according to a new cascade model of string breaking, which corresponds to the fundamental interaction of the theory of the open string. Therefore the recent results of the theory of QCD open string (about the small deviations of the string stretch direction near the longitudinal direction) are used in the algorithm of string breaking. For the fitted values of the free parameters in the process of decay of mother string into two daughter strings the energy (momentum) distributions for the first and second daughter strings are similar to momentum distributions for valence quark and antiquark in meson. This Monte Carlo model with 9 free parameters agrees well with the multiplicity, pseudorapidity, transverse momentum (up to p T =4GeV) distributions and correlations between the average transverse momentum and multiplicity of secondary particles produced by ISR, SS, Tevatron experiments (√s=27 to 1800 GeV). There is quantitative (and qualitative) explanation for correlations between the average transverse momentum and multiplicity for different types of secondary particles (antiprotons, kaons, pions) at √s =1800 GeV. A cascade model of string breaking is a new Monte Carlo model for hadronization which agrees well with the experimental multiplicity, rapidity, transverse momentum distributions of secondary particles produced by e + e - annihilation at E c.m. =3GeV. (author)
Spin chains and string theory.
Kruczenski, Martin
2004-10-15
Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit.
String and brane models with spontaneously or dynamically induced tension
International Nuclear Information System (INIS)
Guendelman, E.I.; Kaganovich, A.; Nissimov, E.; Pacheva, S.
2002-01-01
We study in some detail the properties of a previously proposed new class of string and brane models whose world-sheet (world-volume) actions are built with a modified reparametrization-invariant measure of integration and which do not contain any ad hoc dimensionful parameters. The ratio of the new and the standard Riemannian integration measure densities plays the role of a dynamically generated string or brane tension. The latter is identified as (the magnitude of) an effective (non-Abelian) electric field strength on the world-sheet or world-volume obeying the standard Gauss-law constraint. As a result a simple classical mechanism for confinement via modified-measure 'color' strings is proposed where the colorlessness of the 'hadrons' is an automatic consequence of the new string dynamics
Gusev, Nikolay; Svatovskaya, Larisa; Kucherenko, Alexandr
2018-03-01
The article is devoted to the problem of improving the reliability of monitoring systems for the technical conditions of high-rise buildings. The improvement is based on string sensors with an impulsed excitation method ensuring the maximum signal-to-noise ratio at their output. The influence of the parameters of the monitoring system on the shape of the excitation impulses of the string, and, consequently, on the amplitude of the string vibration of the string converter is also considered in the article. It has been experimentally proved that the parameters of the excitation impulses of the string converters. The article presents the results of the experiments showing the effect of the fronts duration of the excitation impulses on the amplitude of the oscillations of the strings. The influence of the fronts duration of the excitation impulse with the frontal lengths up to 0.5 ms is studied at the excitation impulse duration not exceeding 0.5 times the duration of natural oscillation periods of the string. The experimental data are compared with the theoretical ones and hypotheses explaining their difference are advanced. The article suggests some methods of reducing the influence of the cable-switching equipment system parameters on the amplitude of string oscillations. The possibilities of improving the reliability of the systems developed on the basis of string sensors with an impulsed excitation method and used for monitoring the technical conditions of the high-rise buildings are proposed.
Classical theory of radiating strings
Copeland, Edmund J.; Haws, D.; Hindmarsh, M.
1990-01-01
The divergent part of the self force of a radiating string coupled to gravity, an antisymmetric tensor and a dilaton in four dimensions are calculated to first order in classical perturbation theory. While this divergence can be absorbed into a renormalization of the string tension, demanding that both it and the divergence in the energy momentum tensor vanish forces the string to have the couplings of compactified N = 1 D = 10 supergravity. In effect, supersymmetry cures the classical infinities.
Cosmic string induced CMB maps
International Nuclear Information System (INIS)
Landriau, M.; Shellard, E. P. S.
2011-01-01
We compute maps of CMB temperature fluctuations seeded by cosmic strings using high resolution simulations of cosmic strings in a Friedmann-Robertson-Walker universe. We create full-sky, 18 deg. and 3 deg. CMB maps, including the relevant string contribution at each resolution from before recombination to today. We extract the angular power spectrum from these maps, demonstrating the importance of recombination effects. We briefly discuss the probability density function of the pixel temperatures, their skewness, and kurtosis.
Quantum backreaction in string theory
International Nuclear Information System (INIS)
Evnin, O.
2012-01-01
There are situations in string theory when a finite number of string quanta induce a significant backreaction upon the background and render the perturbation theory infrared-divergent. The simplest example is D0-brane recoil under an impact by closed strings. A more physically interesting case is backreaction on the evolution of a totally compact universe due to closed string gas. Such situations necessitate qualitative amendments to the traditional formulation of string theory in a fixed classical background. In this contribution to the proceedings of the XVII European Workshop on String Theory in Padua, I review solved problems and current investigations in relation to this kind of quantum backreaction effects. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The adjoint string at finite temperature
International Nuclear Information System (INIS)
Damgaard, P.H.
1986-10-01
Expectations for the behavior of the adjoint string at finite temperature are presented. In the Migdal-Kadanoff approximation a real-space renormalization group study of the effective Polyakov like action predicts a deconfinement-like crossover for adjoint sources at a temperature slightly below the deconfinement temperature of fundamental sources. This prediction is compared with a Monte Carlo simulation of SU(2) lattice gauge theory on an 8 3 x2 lattice. (orig.)
The effect of letter string length and report condition on letter recognition accuracy.
Raghunandan, Avesh; Karmazinaite, Berta; Rossow, Andrea S
Letter sequence recognition accuracy has been postulated to be limited primarily by low-level visual factors. The influence of high level factors such as visual memory (load and decay) has been largely overlooked. This study provides insight into the role of these factors by investigating the interaction between letter sequence recognition accuracy, letter string length and report condition. Letter sequence recognition accuracy for trigrams and pentagrams were measured in 10 adult subjects for two report conditions. In the complete report condition subjects reported all 3 or all 5 letters comprising trigrams and pentagrams, respectively. In the partial report condition, subjects reported only a single letter in the trigram or pentagram. Letters were presented for 100ms and rendered in high contrast, using black lowercase Courier font that subtended 0.4° at the fixation distance of 0.57m. Letter sequence recognition accuracy was consistently higher for trigrams compared to pentagrams especially for letter positions away from fixation. While partial report increased recognition accuracy in both string length conditions, the effect was larger for pentagrams, and most evident for the final letter positions within trigrams and pentagrams. The effect of partial report on recognition accuracy for the final letter positions increased as eccentricity increased away from fixation, and was independent of the inner/outer position of a letter. Higher-level visual memory functions (memory load and decay) play a role in letter sequence recognition accuracy. There is also suggestion of additional delays imposed on memory encoding by crowded letter elements. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
Rotating strings in confining AdS/CFT backgrounds
International Nuclear Information System (INIS)
Armoni, Adi; Barbon, Jose L.F.; Petkou, Anastasios C.
2002-01-01
We study semiclassical rotating strings in AdS/CFT backgrounds that exhibit both confinement and finite-size effects. The energy versus spin dispersion relation for short strings is the expected Regge trajectory behaviour, with the same string tension as is measured by the Wilson loop. Long strings probe the interplay between confinement and finite-size effects. In particular, the dispersion relation for long strings shows a characteristic dependence on the string tension and the finite-size scale. (author)
Stiff self-interacting strings at high temperature QCD
Directory of Open Access Journals (Sweden)
S Bakry A.
2018-01-01
Full Text Available We investigate the implications of Nambu-Goto (NG, Lüscher Weisz (LW and Polyakov-Kleinert (PK effective string actions for the Casimir energy and the width of the quantum delocalization of the string in 4-dim pure SU(3 Yang-Mills lattice gauge theory. At a temperature closer to the critical point T/Tc=0.9, we found that the next to leading-order (NLO contributions from the expansion of the NG string in addition to the boundary terms in LW action to decrease the deviations from the lattice data in the intermediate distance scales for both the quark-antiquark QQ̅ potential and broadening of the color tube compared to the free string approximation. We conjecture possible stiffness of the QCD string through studying the effects of extrinsic curvature term in PK action and find a good fitting behavior for the lattice Monte-Carlo data at both long and intermediate quark separations regions.
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.)
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.)
From fractals to wormholes via string theory
International Nuclear Information System (INIS)
Felce, A.G.
1992-01-01
The thesis is in two parts. The first part is devoted to a study of the definition of mass for soliton solutions in string theory. In the context of the low-energy effective field theory, there are three distinct quantities from which one can extract the mass of a soliton: the ADM mass, the static action and the kinetic energy. The three corresponding masses are carefully defined and shown to be equal for a representative class of string solitons, the so-called 'black fivebranes'. Along the way a potential confusion in the definition of the action is cleared up, and it is shown that the kinetic energy of a moving soliton is given in terms of a surface integral at spacelike infinity. This result for the kinetic energy is used to motivate a conjecture about the exact value of soliton masses in string theory: That in conformal field theory the kinetic mass is realized as the norm of the (1,1) deformation induced by the collective coordinate. Such deformations are usually treated as unphysical because they appear to be pure gauge and have zero norm. In a soliton conformal field theory, a finite number of these gauge transformations become physical because of a subtlety involving the boundary at spatial infinity. Some proposals for concrete exploration of this phenomenon are discussed. The second part of the thesis concerns the connection between string theory and an important problem in condensed matter physics. It has recently been shown that the dissipative Hofstadter model (dissipative quantum mechanics of an electron subject to uniform magnetic field and periodic potential in two dimensions) exhibit critical behavior on a network of lines in the dissipation/magnetic field plane. Apart from their obvious condensed matter interest, the corresponding critical theories represent non-trivial solutions of open string field theory containing a tachyon and gauge field background. A detailed account of their properties would be interesting from several points of view
Low energy dynamics of self-dual A1 strings
International Nuclear Information System (INIS)
Gustavsson, Andreas
2003-01-01
We examine the interrelation between the (2,0) supersymmetric six-dimensional effective action for the A 1 theory, and the corresponding low-energy theory for the collective coordinates associated to selfdual BPS strings. We argue that this low energy theory is a two-dimensional N=4 supersymmetric sigma model
International Nuclear Information System (INIS)
Mavromatos, N.E.; Miramontes, J.L.
1988-01-01
We discuss generalised functional relations between the β-functions of bosonic σ-models propagating in graviton and dilaton backgrounds and field variations of the associated effective actions based on these backgrounds. We analyse the constraints on the possible form of the proportionality (non-degenerate) tensors, imposed by classical symmetries of the associated point-like action. As an application we derive the second order [O(α')] effective action and we find that it is consistent with a ghost free combination for both fields. Moreover we show explicitly that this action is related to the one computed within the framework of string tree-amplitudes by field redefinitions. (orig.)
Perspectives on string phenomenology
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...
International Nuclear Information System (INIS)
Boschi, C Degli Esposti; Di Dio, M; Morandi, G; Roncaglia, M
2009-01-01
We derive the dominant contribution to the large-distance decay laws of correlation functions towards their asymptotic limits for a spin chain model that exhibits both Haldane and Neel phases in its ground-state phase diagram. The analytic results are obtained by means of an approximate mapping between a spin-1 anisotropic Hamiltonian onto a fermionic model of noninteracting Bogoliubov quasiparticles related in turn (via Jordan-Wigner transformation) to the XY spin-1/2 chain in a transverse field. This approach allows us to express the spin-1 string operators in terms of fermionic operators so that the dominant contribution to the string correlators at large distances can be computed using the technique of Toeplitz determinants. As expected, we find long-range string order both in the longitudinal and in the transverse channel in the Haldane phase, while in the Neel phase only the longitudinal order survives. In this way, the long-range string order can be explicitly related to the components of the magnetization of the XY model. Moreover, apart from the critical line, where the decay is algebraic, we find that in the gapped phases the decay is governed by an exponential tail multiplied by power-law factors. As regards the usual two points correlation functions, we show that the longitudinal one behaves in a 'dual' fashion with respect to the transverse string correlator, namely both the asymptotic values and the decay laws exchange when the transition line is crossed. For the transverse spin-spin correlator, we always find a finite characteristic length which is an unexpected feature at the critical point. The results of this analysis prove some conjectures put forward in the past. We also comment briefly on the entanglement features of the original system versus those of the effective model. The goodness of the approximation and the analytical predictions are checked versus density-matrix renormalization group calculations
String model of elementary particles
International Nuclear Information System (INIS)
Kikkawa, Keiji
1975-01-01
Recent development of the models of elementary particles is described. The principal features of elementary particle physics can be expressed by quark model, mass spectrum, the Regge behavior of scattering amplitude, and duality. Venezians showed in 1968 that the B function can express these features. From the analysis of mass spectrum, the string model was introduced. The quantization of the string is performed with the same procedure as the ordinary quantum mechanics. The motion of the string is determined by the Nambu-Goto action integral, and the Schroedinger equation is obtained. Mass spectrum from the string model was same as that from the duality model such as Veneziano model. The interaction between strings can be introduced, and the Lagrangian can be formulated. The relation between the string model and the duality model has been studied. The string model is the first theory of non-local field, and the further development is attractive. The relation between this model and the quark model is still not clear. (Kato, T.)
Metastable cosmic strings in realistic models
International Nuclear Information System (INIS)
Holman, R.
1992-01-01
The stability of the electroweak Z-string is investigated at high temperatures. The results show that, while finite temperature corrections can improve the stability of the Z-string, their effect is not strong enough to stabilize the Z-string in the standard electroweak model. Consequently, the Z-string will be unstable even under the conditions present during the electroweak phase transition. Phenomenologically viable models based on the gauge group SU(2) L x SU(2) R x U(1) B-L are then considered, and it is shown that metastable strings exist and are stable to small perturbations for a large region of the parameter space for these models. It is also shown that these strings are superconducting with bosonic charge carriers. The string superconductivity may be able to stabilize segments and loops against dynamical contraction. Possible implications of these strings for cosmology are discussed
String duality transformations in f(R) gravity from Noether symmetry approach
Energy Technology Data Exchange (ETDEWEB)
Capozziello, Salvatore [Dipartimento di Fisica, Università di Napoli ' ' Federico II' ' , Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli (Italy); Gionti, Gabriele S.J. [Specola Vaticana, Vatican City, V-00120, Vatican City State (Vatican City State, Holy See); Vernieri, Daniele, E-mail: capozziello@na.inf.it, E-mail: ggionti@as.arizona.edu, E-mail: vernieri@iap.fr [Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d' Astrophysique de Paris, GReCO, 98bis Bd Arago, 75014 Paris (France)
2016-01-01
We select f(R) gravity models that undergo scale factor duality transformations. As a starting point, we consider the tree-level effective gravitational action of bosonic String Theory coupled with the dilaton field. This theory inherits the Busher's duality of its parent String Theory. Using conformal transformations of the metric tensor, it is possible to map the tree-level dilaton-graviton string effective action into f(R) gravity, relating the dilaton field to the Ricci scalar curvature. Furthermore, the duality can be framed under the standard of Noether symmetries and exact cosmological solutions are derived. Using suitable changes of variables, the string-based f(R) Lagrangians are shown in cases where the duality transformation becomes a parity inversion.
String duality transformations in f(R) gravity from Noether symmetry approach
International Nuclear Information System (INIS)
Capozziello, Salvatore; Gionti, Gabriele S.J.; Vernieri, Daniele
2016-01-01
We select f(R) gravity models that undergo scale factor duality transformations. As a starting point, we consider the tree-level effective gravitational action of bosonic String Theory coupled with the dilaton field. This theory inherits the Busher's duality of its parent String Theory. Using conformal transformations of the metric tensor, it is possible to map the tree-level dilaton-graviton string effective action into f(R) gravity, relating the dilaton field to the Ricci scalar curvature. Furthermore, the duality can be framed under the standard of Noether symmetries and exact cosmological solutions are derived. Using suitable changes of variables, the string-based f(R) Lagrangians are shown in cases where the duality transformation becomes a parity inversion
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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.
The N=1 effective action of F-theory compactifications
International Nuclear Information System (INIS)
Grimm, Thomas W.
2011-01-01
The four-dimensional N=1 effective action of F-theory compactified on a Calabi-Yau fourfold is studied by lifting a three-dimensional M-theory compactification. The lift is performed by using T-duality realized via a Legendre transform on the level of the effective action, and the application of vector-scalar duality in three dimensions. The leading order Kaehler potential and gauge-kinetic coupling functions are determined. In these compactifications two sources of gauge theories are present. Space-time filling non-Abelian seven-branes arise at the singularities of the elliptic fibration of the fourfold. Their couplings are included by resolving the singular fourfold. Generically a U(1) r gauge theory arises from the R-R bulk sector if the base of the elliptically fibered Calabi-Yau fourfold supports 2r harmonic three-forms. The gauge coupling functions depend holomorphically on the complex structure moduli of the fourfold, comprising closed and open string degrees of freedom. The four-dimensional electro-magnetic duality is studied in the three-dimensional effective theory obtained after M-theory compactification. A discussion of matter couplings transforming in the adjoint of the seven-brane gauge group is included.
Constraints on four dimensional effective field theories from string and F-theory
Energy Technology Data Exchange (ETDEWEB)
Baume, Florent
2017-06-21
This thesis is a study of string theory compactifications to four dimensions and the constraints the Effective Field theories must exhibit, exploring both the closed and open sectors. In the former case, we focus on axion monodromy scenarios and the impact the backreaction of the energy density induced by the vev of an axion has on its field excursions. For all the cases studied, we find that the backreaction is small up to a critical value, and the proper field distance is flux independent and at most logarithmic in the axion vev. We then move to the open sector, where we use the framework of F-theory. We first explore the relation between the spectra arising from F-theory GUTs and those coming from a decomposition of the adjoint of E{sub 8} to SU(5) x U(1){sup n}. We find that extending the latter spectrum with new SU(5)-singlet fields, and classifying all possible ways of breaking the Abelian factors, all the spectra coming from smooth elliptic fibration constructed in the literature fit in our classification. We then explore generic properties of the spectra arising when breaking SU(5) to the Standard Model gauge group while retaining some anomaly properties. We finish by a study of F-theory compactications on a singular elliptic fibration via Matrix Factorisation, and find the charged spectrum of two non-Abelian examples.
Constraints on four dimensional effective field theories from string and F-theory
International Nuclear Information System (INIS)
Baume, Florent
2017-01-01
This thesis is a study of string theory compactifications to four dimensions and the constraints the Effective Field theories must exhibit, exploring both the closed and open sectors. In the former case, we focus on axion monodromy scenarios and the impact the backreaction of the energy density induced by the vev of an axion has on its field excursions. For all the cases studied, we find that the backreaction is small up to a critical value, and the proper field distance is flux independent and at most logarithmic in the axion vev. We then move to the open sector, where we use the framework of F-theory. We first explore the relation between the spectra arising from F-theory GUTs and those coming from a decomposition of the adjoint of E 8 to SU(5) x U(1) n . We find that extending the latter spectrum with new SU(5)-singlet fields, and classifying all possible ways of breaking the Abelian factors, all the spectra coming from smooth elliptic fibration constructed in the literature fit in our classification. We then explore generic properties of the spectra arising when breaking SU(5) to the Standard Model gauge group while retaining some anomaly properties. We finish by a study of F-theory compactications on a singular elliptic fibration via Matrix Factorisation, and find the charged spectrum of two non-Abelian examples.
A new approach to strings and superstrings
International Nuclear Information System (INIS)
Sparano, G.
1988-01-01
The subject of this thesis is a new, more general, action principle for strings, superstrings, and extended objects in any number of dimensions. The origin and motivations for this approach can be found in the context of the study of the symmetries of string theories and, more specifically, are related to the application of K.S.K. (Kirillov, Souriau, Kostant) construction to strings. The main results we find are: (A) A classification of string theories analogous to the classification of relativistic point particles as massive, massless and tachionic with or without spin. Nambu-Goto string and Schild null string emerge as special cases of a more general classification of strings. (B) A new method to introduce spin in strings by using a Wess-Zumino term in the action. (C) Several results are obtained through the study of the configuration space which shows a rich topological structure: for the Nambu-Goto string in any number of dimensions it is found the existence of theta states analogous to the theta-vacua of nonabelian gauge theories. For the closed Schild Null string, in four dimensions, this analysis shows Z2 solitons and the possibility of quantizing the system so that the states are spinorial (have half odd integral spin) even though the Lagrangian consists only of bosonic variables. (D) Unlike Nambu-Goto string, the quantization of Schild Null string is consistent in any number of space-time dimensions. Besides these concrete results, the formalism we introduce will hopefully give also new insights in the problem of the hidden symmetries of the string
Kazennikov, Oleg; Wiesendanger, Mario
2009-07-01
Music performance is based on demanding motor control with much practice from young age onward. We have chosen to investigate basic bimanual movements played by violin amateurs and professionals. We posed the question whether position and string changes, two frequent mechanisms, may influence the time interval bowing (right)-fingering (left) coordination. The objective was to measure bimanual coordination, i.e., with or without position changes and string changes. The tendency was that the bimanual coordination was statistically only slightly increased or even unchanged but not perceptible. We conclude that the coordination index is limited up to 100 ms intervals, without any erroneous perception. Although the mentioned position changes and string changes are movements with their timing, they are executed in parallel rather than in series with the bow-fingering coordination.
Transverse structure of the QCD string
International Nuclear Information System (INIS)
Meyer, Harvey B.
2010-01-01
The characterization of the transverse structure of the QCD string is discussed. We formulate a conjecture as to how the stress-energy tensor of the underlying gauge theory couples to the string degrees of freedom. A consequence of the conjecture is that the energy density and the longitudinal-stress operators measure the distribution of the transverse position of the string, to leading order in the string fluctuations, whereas the transverse-stress operator does not. We interpret recent numerical measurements of the transverse size of the confining string and show that the difference of the energy and longitudinal-stress operators is a particularly natural probe at next-to-leading order. Second, we derive the constraints imposed by open-closed string duality on the transverse structure of the string. We show that a total of three independent ''gravitational'' form factors characterize the transverse profile of the closed string, and obtain the interpretation of recent effective string theory calculations: the square radius of a closed string of length β defined from the slope of its gravitational form factor, is given by (d-1/2πσ)log(β/4r 0 ) in d space dimensions. This is to be compared with the well-known result that the width of the open string at midpoint grows as (d-1/2πσ)log(r/r 0 ). We also obtain predictions for transition form factors among closed-string states.
Quantum mechanics vs. general covariance in gravity and string models
International Nuclear Information System (INIS)
Martinec, E.J.
1984-01-01
Quantization of simple low-dimensional systems embodying general covariance is studied. Functional methods are employed in the calculation of effective actions for fermionic strings and 1 + 1 dimensional gravity. The author finds that regularization breaks apparent symmetries of the theory, providing new dynamics for the string and non-trivial dynamics for 1 + 1 gravity. The author moves on to consider the quantization of some generally covariant systems with a finite number of physical degrees of freedom, assuming the existence of an invariant cutoff. The author finds that the wavefunction of the universe in these cases is given by the solution to simple quantum mechanics problems
D-instantons and closed string tachyons in Misner space
International Nuclear Information System (INIS)
Hikida, Yasuaki; Tai, T.-S.
2006-01-01
We investigate closed string tachyon condensation in Misner space, a toy model for big bang universe. In Misner space, we are able to condense tachyonic modes of closed strings in the twisted sectors, which is supposed to remove the big bang singularity. In order to examine this, we utilize D-instanton as a probe. First, we study general properties of D-instanton by constructing boundary state and effective action. Then, resorting to these, we are able to show that tachyon condensation actually deforms the geometry such that the singularity becomes milder
Local grand unification and string theory
International Nuclear Information System (INIS)
Nilles, Hans Peter; Vaudrevange, Patrick K.S.
2009-09-01
The low energy effective action of string theory depends strongly on the process of compactification and the localization of fields in extra dimensions. Explicit string constructions towards the minimal supersymmetric standard model (MSSM) reveal interesting results leading to the concept of local grand unification. Properties of the MSSM indicate that we might live at a special location close to an orbifold fixed point rather than a generic point in Calabi-Yau moduli space. We observe an enhancement of (discrete) symmetries that have various implications for the properties of the MSSM such as proton stability as well as solutions to the flavor problem, the m-problem and the strong CP-problem. (orig.)
The Effect of Friction in Pulleys on the Tension in Cables and Strings
Martell, Eric C.; Martell, Verda Beth
2013-01-01
Atwood's machine is used in countless introductory physics classes as an illustration of Newton's second law. Initially, the analysis is performed assuming the pulley and string are massless and the axle is frictionless. Although the mass of the pulley is often included when the problem is revisited later in the context of rotational dynamics, the…
Casimir energy of rotating string - indirect approach
International Nuclear Information System (INIS)
Hadasz, L.
1999-01-01
Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu-Goto string with the Gauss-Bonnet term in the action. (author)
Casimir Energy of Rotating String --- Indirect Approach
Hadasz, Leszek
1999-04-01
Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu--Goto string with the Gauss--Bonnet term in the action.
Directory of Open Access Journals (Sweden)
Hwang Sungmin
2017-01-01
Full Text Available We present our calculation of the non-relativistic corrections to the heavy quark-antiquark potential up to leading and next-to-leading order (NLO via the effective string theory (EST. Full systematics of effective field theory (EFT are discussed in order for including the NLO contribution that arises in the EST. We also show how the number of dimensionful parameters arising from the EST are reduced by the constraints between the Wilson coeffcients from non-relativistic EFTs for QCD.
Energy Technology Data Exchange (ETDEWEB)
Lake, Matthew J. [The Institute for Fundamental Study, ' ' The Tah Poe Academia Institute' ' , Naresuan University, Phitsanulok (Thailand); Thailand Center of Excellence in Physics, Ministry of Education, Bangkok (Thailand); Harko, Tiberiu [Department of Physics, Babes-Bolyai University, Cluj-Napoca (Romania); Department of Mathematics, University College London (United Kingdom)
2017-10-15
The discovery of a large number of supermassive black holes (SMBH) at redshifts z > 6, when the Universe was only 900 million years old, raises the question of how such massive compact objects could form in a cosmologically short time interval. Each of the standard scenarios proposed, involving rapid accretion of seed black holes or black hole mergers, faces severe theoretical difficulties in explaining the short-time formation of supermassive objects. In this work we propose an alternative scenario for the formation of SMBH in the early Universe, in which energy transfer from superconducting cosmic strings piercing small seed black holes is the main physical process leading to rapid mass increase. As a toy model, the accretion rate of a seed black hole pierced by two antipodal strings carrying constant current is considered. Using an effective action approach, which phenomenologically incorporates a large class of superconducting string models, we estimate the minimum current required to form SMBH with masses of order M = 2 x 10{sup 9} M {sub CircleDot} by z = 7.085. This corresponds to the mass of the central black hole powering the quasar ULAS J112001.48+064124.3 and is taken as a test case scenario for early-epoch SMBH formation. For GUT scale strings, the required fractional increase in the string energy density, due to the presence of the current, is of order 10{sup -7}, so that their existence remains consistent with current observational bounds on the string tension. In addition, we consider an ''exotic'' scenario, in which an SMBH is generated when a small seed black hole is pierced by a higher-dimensional F-string, predicted by string theory. We find that both topological defect strings and fundamental strings are able to carry currents large enough to generate early-epoch SMBH via our proposed mechanism. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
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.)
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
Topological defects in open string field theory
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.
On Thermodynamical Relation Between Rotating Charged BTZ Black Holes and Effective String Theory
Institute of Scientific and Technical Information of China (English)
Alexis Larra(~n)aga
2008-01-01
In this paper we study the first law of thermodynamics for the (2+1)-dimensional rotating charged BTZ black hole considering a pair of thermodynamical systems constructed with the two horizons of this solution. We show that these two systems are similar to the right and left movers of string theory and that the temperature associated with the black hole is the harmonic mean of the temperatures associated with these two systems.
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 ...
Asymptotic Bethe ansatz S-matrix and Landau-Lifshitz-type effective 2d actions
International Nuclear Information System (INIS)
Roiban, R; Tirziu, A; Tseytlin, A A
2006-01-01
Motivated by the desire to relate Bethe ansatz equations for anomalous dimensions found on the gauge-theory side of the AdS/CFT correspondence to superstring theory on AdS 5 x S 5 we explore a connection between the asymptotic S-matrix that enters the Bethe ansatz and an effective two-dimensional quantum field theory. The latter generalizes the standard 'non-relativistic' Landau-Lifshitz (LL) model describing low-energy modes of ferromagnetic Heisenberg spin chain and should be related to a limit of superstring effective action. We find the exact form of the quartic interaction terms in the generalized LL-type action whose quantum S-matrix matches the low-energy limit of the asymptotic S-matrix of the spin chain of Beisert, Dippel and Staudacher (BDS). This generalizes to all orders in the 't Hooft coupling λ an earlier computation of Klose and Zarembo of the S-matrix of the standard LL model. We also consider a generalization to the case when the spin-chain S-matrix contains an extra 'string' phase and determine the exact form of the LL 4-vertex corresponding to the low-energy limit of the ansatz of Arutyunov, Frolov and Staudacher (AFS). We explain the relation between the resulting 'non-relativistic' non-local action and the second-derivative string sigma model. We comment on modifications introduced by strong-coupling corrections to the AFS phase. We mostly discuss the SU(2) sector but also present generalizations to the SL(2) and SU(1|1) sectors, confirming universality of the dressing phase contribution by matching the low-energy limit of the AFS-type spin-chain S-matrix with tree-level string-theory S-matrix
String cosmology in Bianchi type-VI 0 dusty Universe with ...
Indian Academy of Sciences (India)
In this paper, the effect of electromagnetic field in the string Bianchi type-VI0 Universe is investigated. Einstein's field equations have been solved exactly with suitable physical assumptions for two types of strings: (i) massive strings and (ii) Nambu strings. It is found that when the Universe is dominated by massive strings, ...
Deformation of the cubic open string field theory
Energy Technology Data Exchange (ETDEWEB)
Lee, Taejin, E-mail: taejin@kangwon.ac.kr
2017-05-10
We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.
Deformation of the cubic open string field theory
Directory of Open Access Journals (Sweden)
Taejin Lee
2017-05-01
Full Text Available We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.
Deformation of the cubic open string field theory
International Nuclear Information System (INIS)
Lee, Taejin
2017-01-01
We study a consistent deformation of the cubic open bosonic string theory in such a way that the non-planar world sheet diagrams of the perturbative string theory are mapped onto their equivalent planar diagrams of the light-cone string field theory with some length parameters fixed. An explicit evaluation of the cubic string vertex in the zero-slope limit yields the correct relationship between the string coupling constant and the Yang–Mills coupling constant. The deformed cubic open string field theory is shown to produce the non-Abelian Yang–Mills action in the zero-slope limit if it is defined on multiple D-branes. Applying the consistent deformation systematically to multi-string world sheet diagrams, we may be able to calculate scattering amplitudes with an arbitrary number of external open strings.
Thermodynamical string fragmentation
Energy Technology Data Exchange (ETDEWEB)
Fischer, Nadine [Theoretical Particle Physics, Department of Astronomy and Theoretical Physics, Lund University,Sölvegatan 14A, Lund, SE-223 62 (Sweden); School of Physics and Astronomy, Monash University,Wellington Road, Clayton, VIC-3800 (Australia); Sjöstrand, Torbjörn [Theoretical Particle Physics, Department of Astronomy and Theoretical Physics, Lund University,Sölvegatan 14A, Lund, SE-223 62 (Sweden)
2017-01-31
The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly, close-packing of strings is taken into account by making the temperature or string tension environment-dependent. Thirdly, a simple model for hadron rescattering is added. The effect of these modifications is studied, individually and taken together, and compared with data mainly from the LHC. While some improvements can be noted, it turns out to be nontrivial to obtain effects as big as required, and further work is called for.
Remarks on entanglement entropy in string theory
Balasubramanian, Vijay; Parrikar, Onkar
2018-03-01
Entanglement entropy for spatial subregions is difficult to define in string theory because of the extended nature of strings. Here we propose a definition for bosonic open strings using the framework of string field theory. The key difference (compared to ordinary quantum field theory) is that the subregion is chosen inside a Cauchy surface in the "space of open string configurations." We first present a simple calculation of this entanglement entropy in free light-cone string field theory, ignoring subtleties related to the factorization of the Hilbert space. We reproduce the answer expected from an effective field theory point of view, namely a sum over the one-loop entanglement entropies corresponding to all the particle-excitations of the string, and further show that the full string theory regulates ultraviolet divergences in the entanglement entropy. We then revisit the question of factorization of the Hilbert space by analyzing the covariant phase-space associated with a subregion in Witten's covariant string field theory. We show that the pure gauge (i.e., BRST exact) modes in the string field become dynamical at the entanglement cut. Thus, a proper definition of the entropy must involve an extended Hilbert space, with new stringy edge modes localized at the entanglement cut.
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
String model of black hole microstates
International Nuclear Information System (INIS)
Larsen, F.
1997-01-01
The statistical mechanics of black holes arbitrarily far from extremality is modeled by a gas of weakly interacting strings. As an effective low-energy description of black holes the string model provides several highly nontrivial consistency checks and predictions. Speculations on a fundamental origin of the model suggest surprising simplifications in nonperturbative string theory, even in the absence of supersymmetry. copyright 1997 The American Physical Society
Strings, Branes and Symmetries
International Nuclear Information System (INIS)
Westerberg, A.
1997-01-01
Recent dramatic progress in the understanding of the non-perturbative structure of superstring theory shows that extended objects of various kinds, collectively referred to as p-branes, are an integral part of the theory. In this thesis, comprising an introductory text and seven appended research papers, we study various aspects of p-branes with relevance for superstring theory. The first part of the introductory text is a brief review of string theory focussing on the role of p-branes. In particular, we consider the so-called D-branes which currently are attracting a considerable amount of attention. The purpose of this part is mainly to put into context the results of paper 4, 5 and 6 concerning action functionals describing the low-energy dynamics of D-branes. The discussion of perturbative string theory given in this part of the introduction is also intended to provide some background to paper 2 which contains an application of the Reggeon-sewing approach to the construction of string vertices. The second part covers a rather different subject, namely higher-dimensional loop algebras and their cohomology, with the aim of facilitating the reading of papers 1, 3 and 7. The relation to p-branes is to be found in paper 1 where we introduce a certain higher-dimensional generalization of the loop algebra and discuss its potential applicability as a symmetry algebra for p-branes. Papers 3 and 7 are mathematically oriented out-growths of this paper addressing the issue of realizing algebras of this kind, known in physics as current algebras, in terms of pseudo differential operators (PSDOs). The main result of paper 3 is a proof of the equivalence between certain Lie-algebra cocycles on the space of second-quantizable PSDOs
Effective actions for F-theory compactifications and tensor theories
International Nuclear Information System (INIS)
Bonetti, Federico
2014-01-01
In this thesis we study the low-energy effective dynamics emerging from a class of F-theory compactifications in four and six dimensions. We also investigate six-dimensional supersymmetric quantum field theories with self-dual tensors, motivated by the problem of describing the long-wavelength regime of a stack of M5-branes in M-theory. These setups share interesting common features. They both constitute examples of intrinsically non-perturbative physics. On the one hand, in the context of F-theory the non-perturbative character is encoded in the geometric formulation of this class of string vacua, which allows the complexified string coupling to vary in space. On the other hand, the dynamics of a stack of multiple M5-branes flows in the infrared to a novel kind of superconformal field theories in six dimensions - commonly referred to as (2,0) theories - that are expected to possess no perturbative weakly coupled regime and have resisted a complete understanding so far. In particular, no Lagrangian description is known for these models. The strategy we employ to address these two problems is also analogous. A recurring Leitmotif of our work is a transdimensional treatment of the system under examination: in order to extract information about dynamics in d dimensions we consider a (d-1)-dimensional setup. As far as F-theory compactifications are concerned, this is a consequence of the duality between M-theory and F-theory, which constitutes our main tool in the derivation of the effective action of F-theory compactifications. We apply it to six-dimensional F-theory vacua, obtained by taking the internal space to be an elliptically fibered Calabi-Yau threefold, but we also employ it to explore a novel kind of F-theory constructions in four dimensions based on manifolds with Spin(7) holonomy. With reference to six-dimensional (2,0) theories, the transdimensional character of our approach relies in the idea of studying these theories in five dimensions. Indeed, we
A global string with an event horizon
International Nuclear Information System (INIS)
Harari, D.; Polychronakos, A.P.
1990-01-01
An idealized infinite straight global string in flat space-time has a logarithmically divergent energy per unit length. With gravity included, the standard field theoretical model for a straight global string has been shown to give rise to a repulsive gravitational field, and to develop a curvature singularity at a finite proper distance off the string core. Here we point out that alternative (although probably unrealistic) equations of state for the core of the global string produce a non-singular cylindrically symmetric metric with an event horizon at a finite proper distance off the core, such that timelike observers beyond the horizon are bound to move away from the string. The same geometric structure applies to the standard field theoretical model for a vortex in (2+1)-dimensional gravity. Thermal effects in a quantum field theory around the string due to the presence of the horizon are also calculated. (orig.)
Charged string solutions with dilaton and modulus fields
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\
Entropy Corrections for a Charged Black Hole of String Theory*
Institute of Scientific and Technical Information of China (English)
Alexis Larra(n)aga
2011-01-01
We study the entropy of the Gibbons-Macda-Garfinkle-Horowitz-Strominger (GMGHS) charged black hole, originated from the effective action that emerges in the low-energy of string theory, beyond semiclassical approximations. Applying the properties of exact differentials for three variables to the first law thermodynamics ve derive the quantum corrections to the entropy of the black hole. The leading (logarithmic) and non leading corrections to the area law are obtained.
Action-based effects on music perception.
Maes, Pieter-Jan; Leman, Marc; Palmer, Caroline; Wanderley, Marcelo M
2014-01-03
The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral processes. In contrast, embodied accounts of music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework that captures the ways in which the human motor system and its actions can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory, postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modeling), and vice versa, to predict the sensory outcomes of planned actions (forward modeling). Embodied accounts typically refer to inverse modeling to explain action effects on music perception (Leman, 2007). We extend this account by pinpointing forward modeling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system and its actions suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music) cognition in the sense that it needs to be considered as a dynamical process, in which aspects of action, perception, introspection, and social interaction are of crucial importance.
Action-based effects on music perception
Maes, Pieter-Jan; Leman, Marc; Palmer, Caroline; Wanderley, Marcelo M.
2013-01-01
The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral processes. In contrast, embodied accounts of music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework that captures the ways in which the human motor system and its actions can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory, postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modeling), and vice versa, to predict the sensory outcomes of planned actions (forward modeling). Embodied accounts typically refer to inverse modeling to explain action effects on music perception (Leman, 2007). We extend this account by pinpointing forward modeling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system and its actions suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music) cognition in the sense that it needs to be considered as a dynamical process, in which aspects of action, perception, introspection, and social interaction are of crucial importance. PMID:24454299
Action-based effects on music perception
Directory of Open Access Journals (Sweden)
Pieter-Jan eMaes
2014-01-01
Full Text Available The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral phenomena. In contrast, embodied accounts to music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework capturing the ways that the human motor system, and the actions it produces, can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modelling, and vice versa, to predict the sensory outcomes of planned actions (forward modelling. Embodied accounts typically adhere to inverse modelling to explain action effects on music perception (Leman, 2007. We extent this account by pinpointing forward modelling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system, and the action it produces, suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music cognition in the sense that it needs to be considered as a dynamic process, in which aspects of action, perception, introspection, and social interaction are of crucial
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
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.
International Nuclear Information System (INIS)
Schaefer, Mirko
2011-01-01
The main topic of this thesis is the investigation of dynamical properties of coupled Tchebycheff map networks. The results give insights into the chaotic string model and its network generalization from a dynamical point of view. As a first approach, discrete symmetry transformations of the model are studied. These transformations are formulated in a general way in order to be also applicable to similar dynamics on bipartite network structures. The dynamics is studied numerically via Lyapunov measures, spatial correlations, and ergodic properties. It is shown that the zeros of the interaction energy are distinguished only with respect to this specific observable, but not by a more general dynamical principle. The original chaotic string model is defined on a one-dimensional lattice (ring-network) as the underlying network topology. This thesis studies a modification of the model based on the introduction of tunable disorder. The effects of inhomogeneous coupling weights as well as small-world perturbations of the ring-network structure on the interaction energy are discussed. Synchronization properties of the chaotic string model and its network generalization are studied in later chapters of this thesis. The analysis is based on the master stability formalism, which relates the stability of the synchronized state to the spectral properties of the network. Apart from complete synchronization, where the dynamics at all nodes of the network coincide, also two-cluster synchronization on bipartite networks is studied. For both types of synchronization it is shown that depending on the type of coupling the synchronized dynamics can display chaotic as well as periodic or quasi-periodic behaviour. The semi-analytical calculations reveal that the respective synchronized states are often stable for a wide range of coupling values even for the ring-network, although the respective basins of attraction may inhabit only a small fraction of the phase space. To provide
Formation of Electron Strings in Narrow Band Polar Semiconductors
Kusmartsev, F. V.
2000-01-01
We show that linear electron strings may arise in polar semiconductors. A single string consists of M spinless fermions trapped by an extended polarization well of a cigar shape. Inside the string the particles are free although they interact with each other via Coulomb forces. The strings arise as a result of an electronic phase separation associated with an instability of small adiabatic polarons. We have found the length of the string which depends on dielectric constants of semiconductors. The appearance of these electron strings may have an impact on the effect of stripe formation observed in a variety of high- Tc experiments.
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
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.
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.)
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.
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)
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
Perturbation theory for quantized string fields
International Nuclear Information System (INIS)
Thorn, C.B.; Florida Univ., Gainesville
1987-01-01
We discuss the problem of gauge fixing in string field theory. We show that BRST invariance requires the gauge-fixed action to contain terms cubic in the ghost... of ghost of ghost fields. The final BRST invariant gauge-fixed action for the gauge b 0 A=0 is extremely simple: with the proper interpretation (as given in this article), it is essentially the one anticipated earlier in the work of Giddings, Martinec, and Witten in their analysis of the BRST invariant world-sheet approach to string theory. We derive the Feynman rules from this action and explain in detail how the sum over sufaces of the BRST first-quantized string is reproduced. This result depends crucially on the correct assignment for the Grassmann character of the string field and its ghost... of ghost of ghost string fields. If all these fields are unified in a single string field Φ containing all ghost numbers, the requirements is that Φ be uniformly Grassmann odd. Finally, we do some sample calculations which provide some simple checks on our general results. (orig.)
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.
Defect branes as Alice strings
International Nuclear Information System (INIS)
Okada, Takashi; Sakatani, Yuho
2015-01-01
There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.
Defect branes as Alice strings
Energy Technology Data Exchange (ETDEWEB)
Okada, Takashi [Theoretical Biology Laboratory, RIKEN,Wako 351-0198 (Japan); Sakatani, Yuho [Department of Physics and Astronomy,Seoul National University, Seoul 151-747 (Korea, Republic of)
2015-03-25
There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.
International Nuclear Information System (INIS)
Kachru, Shamit; McAllister, Liam; Sundrum, Raman
2007-01-01
We study sequestering, a prerequisite for flavor-blind supersymmetry breaking in several high-scale mediation mechanisms, in compactifications of type IIB string theory. We find that although sequestering is typically absent in unwarped backgrounds, strongly warped compactifications do readily sequester. The AdS/CFT dual description in terms of conformal sequestering plays an important role in our analysis, and we establish how sequestering works both on the gravity side and on the gauge theory side. We pay special attention to subtle compactification effects that can disrupt sequestering. Our result is a step toward realizing an appealing pattern of soft terms in a KKLT compactification
Leon, Alejandro
2012-02-01
In this work we study the dynamical properties of a finite array of nanomagnets in artificial kagome spin ice at room temperature. The dynamic response of the array of nanomagnets is studied by implementing a ``frustrated celular aut'omata'' (FCA), based in the charge model. In this model, each dipole is replaced by a dumbbell of two opposite charges, which are situated at the neighbouring vertices of the honeycomb lattice. The FCA simulations, allow us to study in real-time and deterministic way, the dynamic of the system, with minimal computational resource. The update function is defined according to the coordination number of vertices in the system. Our results show that for a set geometric parameters of the array of nanomagnets, the system exhibits high density of Dirac strings and high density emergent magnetic monopoles. A study of the effect of disorder in the arrangement of nanomagnets is incorporated in this work.
5D Black Holes and Matrix Strings
Dijkgraaf, R; Verlinde, Herman L
1997-01-01
We derive the world-volume theory, the (non)-extremal entropy and background geometry of black holes and black strings constructed out of the NS IIA fivebrane within the framework of matrix theory. The CFT description of strings propagating in the black hole geometry arises as an effective field theory.
A non-linear σ-model related to the fine structure of strings
International Nuclear Information System (INIS)
Abdalla, E.; Abdalla, M.C.B.; Lima Santos, A.
1986-07-01
It is shown that a σ-model related to the strings via Polyakov's construction is classically (but not quantum mechanically) integrable. When fermions are suitably introduced the exact on shell solution is discussed. In the locally supersymmetric case the 1/D expansion is used to integrate out the σ-model fields leaving an effective action for graviton and gravitino. (author)
From big crunch to big bang: A quantum string cosmology perspective
International Nuclear Information System (INIS)
Maharana, Jnanadeva
2002-01-01
The scenario that the Universe contracts towards a big crunch and then undergoes a transition to an expanding universe is envisaged in the quantum string cosmology approach. The Wheeler-DeWitt (WDW) equation is solved exactly for an exponential dilaton potential. An S-duality invariant cosmological effective action for type IIB theory is considered to derive classical solutions and solve WDW equations
Jejjala, Vishnumohan
2002-01-01
This Thesis explores aspects of superstring theory on orbifold spaces and applies some of the intuition gleaned from the study of the non-commutative geometry of space-time to understanding the fractional quantum Hall effect. The moduli space of vacua of marginal and relevant deformations of N = 4 super-Yang-Mills gauge theory in four dimensions is interpreted in terms of non-commutative geometry. A formalism for thinking about the algebraic geometry of the moduli space is developed. Within this framework, the representation theory of the algebras studied provides a natural exposition of D-brane fractionation. The non-commutative moduli space of deformations preserving N = 1 supersymmetry is examined in detail through various examples. In string theory, by the AdS/CFT correspondence, deformations of the N = 4 field theory are dual to the near-horizon geometries of D-branes on orbifolds of AdS5 x S 5. The physics of D-branes on the dual AdS backgrounds is explored. Quivers encapsulate the matter content of supersymmetric field theories on the worldvolumes of D-branes at orbifold singularities. New techniques for constructing quivers are presented here. When N is a normal subgroup of a finite group G, the quiver corresponding to fixed points of the orbifold M/G is computed from a G/N action on the quiver corresponding to M/G . These techniques prove useful for constructing non-Abelian quivers and for examining discrete torsion orbifolds. Quivers obtained through our constructions contain interesting low-energy phenomenology. The matter content on a brane at an isolated singularity of the Delta27 orbifold embeds the Standard Model. The symmetries of the quiver require exactly three generations of fields in the particle spectrum. Lepton masses are suppressed relative to quark masses because lepton Yukawa couplings do not appear in the superpotential. Lepton masses are generated through the Kahler potential and are related to the supersymmetry breaking scale. The model
Differential geometry in string models
International Nuclear Information System (INIS)
Alvarez, O.
1986-01-01
In this article the author reviews the differential geometric approach to the quantization of strings. A seminal paper demonstrates the connection between the trace anomaly and the critical dimension. The role played by the Faddeev-Popov ghosts has been instrumental in much of the subsequent work on the quantization of strings. This paper discusses the differential geometry of two dimensional surfaces and its importance in the quantization of strings. The path integral quantization approach to strings will be carefully analyzed to determine the correct effective measure for string theories. The choice of measure for the path integral is determined by differential geometric considerations. Once the measure is determined, the manifest diffeomorphism invariance of the theory will have to be broken by using the Faddeev-Popov ansatz. The gauge fixed theory is studied in detail with emphasis on the role of conformal and gravitational anomalies. In the analysis, the path integral formulation of the gauge fixed theory requires summing over all the distinct complex structures on the manifold
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
International Nuclear Information System (INIS)
Skenderis, Kostas
2007-01-01
The book 'String Theory in a Nutshell' by Elias Kiritsis provides a comprehensive introduction to modern string theory. String theory is the leading candidate for a theory that successfully unifies all fundamental forces of nature, including gravity. The subject has been continuously developing since the early 1970s, with classic textbooks on the subject being those of Green, Schwarz and Witten (1987) and Polchinski (1998). Since the latter was published there have been substantial developments, in particular in understanding black holes and gravity/gauge theory dualities. A textbook treatment of this important material is clearly needed, both by students and researchers in string theory and by mathematicians and physicists working in related fields. This book has a good selection of material, starting from basics and moving into classic and modern topics. In particular, Kiritsis' presentation of the basic material is complementary to that of the earlier textbooks and he includes a number of topics which are not easily found or covered adequately elsewhere, for example, loop corrections to string effective couplings. Overall the book nicely covers the major advances of the last ten years, including (non-perturbative) string dualities, black hole physics, AdS/CFT and matrix models. It provides a concise but fairly complete introduction to these subjects which can be used both by students and by researchers. Moreover the emphasis is on results that are reasonably established, as is appropriate for a textbook; concise summaries are given for subjects which are still in flux, with references to relevant reviews and papers. A positive feature of the book is that the bibliography sections at the end of each chapter provide a comprehensive guide to the literature. The bibliographies point to reviews and pedagogical papers on subjects covered in this book as well as those that were omitted. It is rare for a textbook to contain such a self-contained and detailed guide to
Directory of Open Access Journals (Sweden)
Zhanghua Lian
2015-03-01
Full Text Available Multi-stage SRV fracturing in horizontal wells is a new technology developed at home and abroad in recent years to effectively develop shale gas or low-permeability reservoirs, but on the other hand makes the mechanical environment of fracturing strings more complicated at the same time. In view of this, based on the loading features of tubing strings during the multi-stage fracturing of a horizontal well, mechanical models were established for three working cases of multiple packer setting, open differential-pressure sliding sleeve, and open ball-injection sliding sleeve under a hold-down packer. Moreover, mathematical models were respectively built for the above three cases. According to the Lame formula and Von Mises stress calculation formula for the thick-walled cylinder in the theory of elastic mechanics, a mathematical model was also established to calculate the equivalent stress for tubing string safety evaluation when the fracturing string was under the combined action of inner pressure, external squeezing force and axial stress, and another mathematical model was built for the mechanical strength and safety evaluation of multi-stage fracturing strings. In addition, a practical software was developed for the mechanical safety evaluation of horizontal well multi-stage fracturing strings according to the mathematical model developed for the mechanical calculation of the multi-packer string in horizontal wells. The research results were applied and verified in a gas well of Tahe Oilfield in the Tarim Basin with excellent effects, providing a theoretical basis and a simple and reliable technical means for optimal design and safety evaluation of safe operational parameters of multi-stage fracturing strings in horizontal wells.
International Nuclear Information System (INIS)
Metsaev, R.R.; Tseytlin, A.A.
1987-01-01
We prove the on-shell equivalence of the order α' terms in the string effective equations (for the graviton, dilaton and the antisymmetric tensor) to the vanishing of the corresponding (two-loop) terms in the Weyl anomaly coefficients for the general bosonic σ-model. We first determine the α' term in the string effective action starting with the known expression for the 3- and 4-point string amplitudes. Then we compute the two-loop β-function in the general σ-model with the antisymmetric tensor coupling. Special emphasis is made on the renormalization scheme dependence of the β-function. Our result disagrees with the previously known one and cannot be manifestly expressed in terms of the generalized curvature for the connection with torsion. We also prove (to the order α' 2 ) that the parallelizable spaces are solutions of the string equations of motion and establish the complete 3-loop expression for the 'central charge' coefficient. (orig.)
Cooperative strings and glassy interfaces.
Salez, Thomas; Salez, Justin; Dalnoki-Veress, Kari; Raphaël, Elie; Forrest, James A
2015-07-07
We introduce a minimal theory of glass formation based on the ideas of molecular crowding and resultant string-like cooperative rearrangement, and address the effects of free interfaces. In the bulk case, we obtain a scaling expression for the number of particles taking part in cooperative strings, and we recover the Adam-Gibbs description of glassy dynamics. Then, by including thermal dilatation, the Vogel-Fulcher-Tammann relation is derived. Moreover, the random and string-like characters of the cooperative rearrangement allow us to predict a temperature-dependent expression for the cooperative length ξ of bulk relaxation. Finally, we explore the influence of sample boundaries when the system size becomes comparable to ξ. The theory is in agreement with measurements of the glass-transition temperature of thin polymer films, and allows quantification of the temperature-dependent thickness hm of the interfacial mobile layer.
The Gravity of Dark Vortices: Effective Field Theory for Branes and Strings Carrying Localized Flux
Burgess, C P; Williams, M
2015-01-01
A Nielsen-Olesen vortex usually sits in an environment that expels the flux that is confined to the vortex, so flux is not present both inside and outside. We construct vortices for which this is not true, where the flux carried by the vortex also permeates the `bulk' far from the vortex. The idea is to mix the vortex's internal gauge flux with an external flux using off-diagonal kinetic mixing. Such `dark' vortices could play a phenomenological role in models with both cosmic strings and a dark gauge sector. When coupled to gravity they also provide explicit ultra-violet completions for codimension-two brane-localized flux, which arises in extra-dimensional models when the same flux that stabilizes extra-dimensional size is also localized on space-filling branes situated around the extra dimensions. We derive simple formulae for observables such as defect angle, tension, localized flux and on-vortex curvature when coupled to gravity, and show how all of these are insensitive to much of the microscopic detail...
Techniques Used in String Matching for Network Security
Jamuna Bhandari
2014-01-01
String matching also known as pattern matching is one of primary concept for network security. In this area the effectiveness and efficiency of string matching algorithms is important for applications in network security such as network intrusion detection, virus detection, signature matching and web content filtering system. This paper presents brief review on some of string matching techniques used for network security.
On the effective theory of type II string compactifications on nilmanifolds and coset spaces
International Nuclear Information System (INIS)
Caviezel, Claudio
2009-01-01
In this thesis we analyzed a large number of type IIA strict SU(3)-structure compactifications with fluxes and O6/D6-sources, as well as type IIB static SU(2)-structure compactifications with fluxes and O5/O7-sources. Restricting to structures and fluxes that are constant in the basis of left-invariant one-forms, these models are tractable enough to allow for an explicit derivation of the four-dimensional low-energy effective theory. The six-dimensional compact manifolds we studied in this thesis are nilmanifolds based on nilpotent Lie-algebras, and, on the other hand, coset spaces based on semisimple and U(1)-groups, which admit a left-invariant strict SU(3)- or static SU(2)-structure. In particular, from the set of 34 distinct nilmanifolds we identified two nilmanifolds, the torus and the Iwasawa manifold, that allow for an AdS 4 , N = 1 type IIA strict SU(3)-structure solution and one nilmanifold allowing for an AdS 4 , N = 1 type IIB static SU(2)-structure solution. From the set of all the possible six-dimensional coset spaces, we identified seven coset spaces suitable for strict SU(3)-structure compactifications, four of which also allow for a static SU(2)-structure compactification. For all these models, we calculated the four-dimensional low-energy effective theory using N = 1 supergravity techniques. In order to write down the most general four-dimensional effective action, we also studied how to classify the different disconnected ''bubbles'' in moduli space. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Carlip, S [Department of Physics, University of California, Davis, CA 95616 (United States)
2006-10-21
, it could easily be missed-but these are minor drawbacks. Readers will find clear answers to many 'frequently asked questions.' Are D-branes really necessary? Polchinski begins with T-duality for the closed string, and shows that the extension to open strings requires the existence of D-branes. How does string theory incorporate gravity? The two standard answers are that string theory contains a massless spin two 'graviton' and that consistent string propagation in a curved background requires that the background metric satisfy the Einstein field equations; Polchinski links the two, showing that the background metric can be viewed as a coherent state of the spin two excitations. Volume II, Superstring Theory and Beyond, extends Volume I to superstring theory, and then proceeds to treat a range of more advanced subjects: effective actions for branes, dualities and equivalences among string theories, M theory, stringy black holes, compactifications and four-dimensional field theories, and the like. The tone of this volume changes a bit-it is not as self-contained, and reads less like a textbook and more like an extended review article. I suspect, for example, that few students without a strong background in field theory will follow the discussion of anomalies in chapter 12. The change can be largely attributed to the content: the superstring is inherently more difficult than the bosonic string, and the newer material is not as deeply understood. But there are a few weaknesses in presentation as well: for instance, a discussion in chapter 11 of the relationship between symmetries and constraints omits any explanation of how one decides whether a transformation generates a symmetry or a constraint. Any two-volume book on string theory is necessarily incomplete. In his introduction, Polchinski cites the lack of a more thorough treatment of compactifications on curved manifolds. I would personally have liked to see more about noncritical strings and
Collisions of cosmic F- and D-strings
International Nuclear Information System (INIS)
Jones, N.
2004-01-01
Recent theoretical advances and upcoming experimental measurements make the testing of generic predictions of string theory models of cosmology feasible. Brane anti-brane models of inflation within superstring theory are promising as string theory descriptions of the physics of the early universe. While varied in their construction, these models can have the generic and observable consequence that cosmic strings will be abundant in the early universe. This leads to possible detectable effects in the cosmic microwave background, gravitational wave physics and gravitational lensing. Detailed calculations of cosmic string interactions within string theory are presented, in order to distinguish these cosmic strings from those in more conventional theories; these interaction probabilities can be very different from conventional 4-dimension strings, providing the possibility of experimental tests of string theory. (authors)
BPS dynamics of the triple (p,q) string junction
International Nuclear Information System (INIS)
Rey, S.-J.; Yee, J.-T.
1998-01-01
We study the dynamics of the triple junction of (p,q) strings in type IIB string theory. We probe the tension and mass density of (p,q) strings by studying harmonic fluctuations of the triple junction. We show that they agree perfectly with the BPS formula provided a suitable geometric interpretation of the junction is given. We provide a precise statement of the BPS limit and force-balance property. At weak coupling and sufficiently dense limit, we argue that a (p,q) string embedded in the string network is a 'wiggly string', whose low-energy dynamics can be described via a renormalization group evolved, smooth effective non-relativistic string. We also suggest the possibility that, upon type IIB strings being promoted to the M-theory membrane, there can exist 'evanescent' bound-states at the triple junction in the continuum. (orig.)
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.)
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.)
Free bosonic string field theory without supplementary fields
International Nuclear Information System (INIS)
Embacher, F.
1987-01-01
A covariant local action for free bosonic string fields is constructed without the use of supplementary fields. The open string case is treated in detail. Up to a mathematical conjecture which is likely to hold it is shown that the Virasoro constraints arise as a special choice of gauge. The kinetic operator turns out to be extremely simple, the gauge transformation law arising rather implicitly. The case of closed strings is briefly discussed. 25 refs. (Author)
Cosmic string induced peculiar velocities
International Nuclear Information System (INIS)
van Dalen, A.; Schramm, D.N.
1987-02-01
We calculate analytically the probability distribution for peculiar velocities on scales from 10h -1 to 60h -1 Mpc with cosmic string loops as the dominant source of primordial gravitational perturbations. We consider a range of parameters βGμ appropriate for both hot (HDM) and cold (CDM) dark matter scenarios. An Ω = 1 CDM Universe is assumed with the loops randomly placed on a smooth background. It is shown how the effects can be estimated of loops breaking up and being born with a spectrum of sizes. It is found that to obtain large scale streaming velocities of at least 400 km/s it is necessary that either a large value for βGμ or the effect of loop fissioning and production details be considerable. Specifically, for optimal CDM string parameters Gμ = 10 -6 , β = 9, h = .5, and scales of 60h -1 Mpc, the parent size spectrum must be 36 times larger than the evolved daughter spectrum to achieve peculiar velocities of at least 400 km/s with a probability of 63%. With this scenario the microwave background dipole will be less than 800 km/s with only a 10% probability. The string induced velocity spectrum is relatively flat out to scales of about 2t/sub eq//a/sub eq/ and then drops off rather quickly. The flatness is a signature of string models of galaxy formation. With HDM a larger value of βGμ is necessary for galaxy formation since accretion on small scales starts later. Hence, with HDM, the peculiar velocity spectrum will be larger on large scales and the flat region will extend to larger scales. If large scale peculiar velocities greater than 400 km/s are real then it is concluded that strings plus CDM have difficulties. The advantages of strings plus HDM in this regard will be explored in greater detail in a later paper. 27 refs., 4 figs., 1 tab
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
String fragmentation; La fragmentation des cordes
Energy Technology Data Exchange (ETDEWEB)
Drescher, H.J.; Werner, K. [Laboratoire de Physique Subatomique et des Technologies Associees - SUBATECH, Centre National de la Recherche Scientifique, 44 - Nantes (France)
1997-10-01
The classical string model is used in VENUS as a fragmentation model. For the soft domain simple 2-parton strings were sufficient, whereas for higher energies up to LHC, the perturbative regime of the QCD gives additional soft gluons, which are mapped on the string as so called kinks, energy singularities between the leading partons. The kinky string model is chosen to handle fragmentation of these strings by application of the Lorentz invariant area law. The `kinky strings` model, corresponding to the perturbative gluons coming from pQCD, takes into consideration this effect by treating the partons and gluons on the same footing. The decay law is always the Artru-Menessier area law which is the most realistic since it is invariant to the Lorentz and gauge transformations. For low mass strings a manipulation of the rupture point is necessary if the string corresponds already to an elementary particle determined by the mass and the flavor content. By means of the fragmentation model it will be possible to simulate the data from future experiments at LHC and RHIC 3 refs.
String theory of the Regge intercept.
Hellerman, S; Swanson, I
2015-03-20
Using the Polchinski-Strominger effective string theory in the covariant gauge, we compute the mass of a rotating string in D dimensions with large angular momenta J, in one or two planes, in fixed ratio, up to and including first subleading order in the large J expansion. This constitutes a first-principles calculation of the value for the order-J(0) contribution to the mass squared of a meson on the leading Regge trajectory in planar QCD with bosonic quarks. For open strings with Neumann boundary conditions, and for closed strings in D≥5, the order-J(0) term in the mass squared is exactly calculated by the semiclassical approximation. This term in the expansion is universal and independent of the details of the theory, assuming only D-dimensional Poincaré invariance and the absence of other infinite-range excitations on the string world volume, beyond the Nambu-Goldstone bosons.
CERN. Geneva
2014-01-01
The presence of the surrounding medium makes their dynamics dramatically different from those of ordinary string-like objects propagating in empty space, leading to quite peculiar phenomena, observed in experiments and simulations. I will argue that the effective theory provides an optimal theoretical framework to understand such phenomena, and to make precise quantitative predictions about them.
The effective action for chiral fermions
International Nuclear Information System (INIS)
Alvarez-Gaume, L.
1985-01-01
This paper reports on recent work which given an exact characterization of the imaginary part of the effective action for chiral fermions in 2n dimensions in terms of the spectral asymmetry of a suitable (2n+1)-dimensional operator. In order to keep the discussion as simple as possible, the author concentrates on four dimensional fermions with arbitrary external gauge fields. This approach can be extended without difficulty to higher dimensions and also to include external gravitational fields
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
Exploring soft constraints on effective actions
Energy Technology Data Exchange (ETDEWEB)
Bianchi, Massimo; Guerrieri, Andrea L. [Dipartimento di Fisica, Università di Roma “Tor Vergata”,I.N.F.N. Sezione di Roma “Tor Vergata”,Via della Ricerca Scientifica, Roma, 00133 (Italy); Huang, Yu-tin; Lee, Chao-Jung [Department of Physics and Astronomy, National Taiwan University,No. 1 Roosevelt Road Sec. 4, Taipei, Taiwan (China); Wen, Congkao [Dipartimento di Fisica, Università di Roma “Tor Vergata”,I.N.F.N. Sezione di Roma “Tor Vergata”,Via della Ricerca Scientifica, Roma, 00133 (Italy)
2016-10-10
We study effective actions for simultaneous breaking of space-time and internal symmetries. Novel features arise due to the mixing of Goldstone modes under the broken symmetries which, in contrast to the usual Adler’s zero, leads to non-vanishing soft limits. Such scenarios are common for spontaneously broken SCFT’s. We explicitly test these soft theorems for N=4 sYM in the Coulomb branch both perturbatively and non-perturbatively. We explore the soft constraints systematically utilizing recursion relations. In the pure dilaton sector of a general CFT, we show that all amplitudes up to order s{sup n}∼∂{sup 2n} are completely determined in terms of the k-point amplitudes at order s{sup k} with k≤n. Terms with at most one derivative acting on each dilaton insertion are completely fixed and coincide with those appearing in the conformal DBI, i.e. DBI in AdS. With maximal supersymmetry, the effective actions are further constrained, leading to new non-renormalization theorems. In particular, the effective action is fixed up to eight derivatives in terms of just one unknown four-point coefficient and one more coefficient for ten-derivative terms. Finally, we also study the interplay between scale and conformal invariance in this context.
Influence of verbal instructions on effect-based action control.
Eder, Andreas B; Dignath, David
2017-03-01
According to ideomotor theory, people use bidirectional associations between movements and their effects for action selection and initiation. Our experiments examined how verbal instructions of action effects influence response selection without prior experience of action effects in a separate acquisition phase. Instructions for different groups of participants specified whether they should ignore, attend, learn, or intentionally produce acoustic effects produced by button presses. Results showed that explicit instructions of action-effect relations trigger effect-congruent action tendencies in the first trials following the instruction; in contrast, no evidence for effect-based action control was observed in these trials when instructions were to ignore or to attend to the action effects. These findings show that action-effect knowledge acquired through verbal instruction and direct experience is similarly effective for effect-based action control as long as the relation between the movement and the effect is clearly spelled out in the instruction.
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)
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.
Thermodynamics of quantum strings
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)
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
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
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
Hidden gravity in open-string field theory
International Nuclear Information System (INIS)
Siegel, W.
1994-01-01
We clarify the nature of the graviton as a bound state in open-string field theory: The flat metric in the action appears as the vacuum value of an open string field. The bound state appears as a composite field in the free field theory
Simple model of string with colour degrees of freedom
Hadasz, Leszek
1994-03-01
We consider a simple model of string with colour charges on its ends. The model is constructed by rewriting the action describing classical spinless as well as spinning particles with colour charge in terms of fields living on the “string worldsheet” bounded by trajectories of the particles.
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.)
Effective 1.0: An Analytic Effective Action Analysis Library
Hetherington, James P. J.; Stephens, Philip
2006-01-01
Effective is a C++ library which provides the user a toolbox to study the effective action of an arbitrary field theory. From the field content, gauge groups and representations an appropriate action is generated symbolically. The effective potential, mass spectrum, field couplings and vacuum expectation values are then obtained automatically; tree level results are obtained analytically while many tools, both numeric and analytic, provide a variety of approaches to deal with the one-loop cor...
Some tree-level string amplitudes in the NSR formalism
International Nuclear Information System (INIS)
Becker, Katrin; Becker, Melanie; Melnikov, Ilarion V.; Robbins, Daniel; Royston, Andrew B.
2015-01-01
We calculate tree level scattering amplitudes for open strings using the NSR formalism. We present a streamlined symmetry-based and pedagogical approach to the computations, which we first develop by checking two-, three-, and four-point functions involving bosons and fermions. We calculate the five-point amplitude for massless gluons and find agreement with an earlier result by Brandt, Machado and Medina. We then compute the five-point amplitudes involving two and four fermions respectively, the general form of which has not been previously obtained in the NSR formalism. The results nicely confirm expectations from the supersymmetric F 4 effective action. Finally we use the prescription of Kawai, Lewellen and Tye (KLT) to compute the amplitudes for the closed string sector.
Stationary closed strings in five-dimensional flat spacetime
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.
The Development of a String Sight-Reading Pitch Skill Hierarchy
Alexander, Michael L.; Henry, Michele L.
2012-01-01
This study was designed to determine a pitch skill hierarchy for string sight-reading, to determine the effects of key on string sight-reading achievement, and to determine the validity of a tonal pattern system as a measurement of melodic sight-reading skill for string players. High school string students (n = 94) obtained a mean score of 27.28…
Bosonization and current algebra of spinning strings
International Nuclear Information System (INIS)
Stern, A.
1996-01-01
We write down a general geometric action principle for spinning strings in d-dimensional Minkowski space, which is formulated without the use of Grassmann coordinates. Instead, it is constructed in terms of the pull-back of a left invariant Maurer-Cartan form on the d-dimensional Poincare group to the world-sheet. The system contains some interesting special cases. Among them are the Nambu string (as well as, null and tachyonic strings) where the spin vanishes, and also the case of a string with a spin current - but no momentum current. We find the general form for the Virasoro generators, and show that they are first class constraints in the Hamiltonian formulation of the theory. The current algebra associated with the momentum and angular momentum densities are shown, in general, to contain rather complicated anomaly terms which obstruct quantization. As expected, the anomalies vanish when one specializes to the case of the Nambu string, and there one simply recovers the algebra associated with the Poincare loop group. We speculate that there exist other cases where the anomalies vanish, and that these cases give the bosonization of the known pseudoclassical formulations of spinning strings. (orig.)
International Nuclear Information System (INIS)
Carlip, S
2006-01-01
-but these are minor drawbacks. Readers will find clear answers to many 'frequently asked questions.' Are D-branes really necessary? Polchinski begins with T-duality for the closed string, and shows that the extension to open strings requires the existence of D-branes. How does string theory incorporate gravity? The two standard answers are that string theory contains a massless spin two 'graviton' and that consistent string propagation in a curved background requires that the background metric satisfy the Einstein field equations; Polchinski links the two, showing that the background metric can be viewed as a coherent state of the spin two excitations. Volume II, Superstring Theory and Beyond, extends Volume I to superstring theory, and then proceeds to treat a range of more advanced subjects: effective actions for branes, dualities and equivalences among string theories, M theory, stringy black holes, compactifications and four-dimensional field theories, and the like. The tone of this volume changes a bit-it is not as self-contained, and reads less like a textbook and more like an extended review article. I suspect, for example, that few students without a strong background in field theory will follow the discussion of anomalies in chapter 12. The change can be largely attributed to the content: the superstring is inherently more difficult than the bosonic string, and the newer material is not as deeply understood. But there are a few weaknesses in presentation as well: for instance, a discussion in chapter 11 of the relationship between symmetries and constraints omits any explanation of how one decides whether a transformation generates a symmetry or a constraint. Any two-volume book on string theory is necessarily incomplete. In his introduction, Polchinski cites the lack of a more thorough treatment of compactifications on curved manifolds. I would personally have liked to see more about noncritical strings and Liouville theory and about the Green-Schwarz superstring
Topological Strings and Integrable Hierarchies
Aganagic, M; Klemm, A D; Marino, M; Vafa, C; Aganagic, Mina; Dijkgraaf, Robbert; Klemm, Albrecht; Marino, Marcos; Vafa, Cumrun
2006-01-01
We consider the topological B-model on local Calabi-Yau geometries. We show how one can solve for the amplitudes by using W-algebra symmetries which encodes the symmetries of holomorphic diffeomorphisms of the Calabi-Yau. In the highly effective fermionic/brane formulation this leads to a free fermion description of the amplitudes. Furthermore we argue that topological strings on Calabi-Yau geometries provide a unifying picture connecting non-critical (super)strings, integrable hierarchies, and various matrix models. In particular we show how the ordinary matrix model, the double scaling limit of matrix models, and Kontsevich-like matrix model are all related and arise from studying branes in specific local Calabi-Yau three-folds. We also show how A-model topological string on P^1 and local toric threefolds (and in particular the topological vertex) can be realized and solved as B-model topological string amplitudes on a Calabi-Yau manifold.
Semilocal and electroweak strings
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
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...
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
Derandomizing from random strings
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
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.)
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...
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.
QCD bosonization and the meson effective action
International Nuclear Information System (INIS)
Praschifka, J.; Roberts, C.D.; Cahill, R.T.
1987-01-01
A bosonization of quantum chromodynamics (QCD) is employed to derive a meson effective action, thus providing a direct link between QCD and meson phenomenology. As an example of this approach expressions are obtained for the meson parameters associated with the analysis of ω→3π decay. The bosonization also directly motivates a divergence-free, global color-symmetry model for mesons, which is seen to be a generalization of various phenomenological models. Good estimates are obtained for the values of several of the meson parameters
Effective action calculation in lattice QCD
International Nuclear Information System (INIS)
Hoek, J.
1983-01-01
A method (called the effective action method) devised to make analytic calculations in Quantum Chromodynamics in the region of strong coupling is presented. First, the author deals with developing the calculation of a strong coupling expansion of the generating functional for gauge systems on a lattice with arbitrary sources. An accompanying manual describes the implementation of this calculation on a computer. The next step consists of substituting the expressions for the one-link free energies for a specific gauge group in the result of the previous calculation. This process of substitution, together with the replacement of the sources by a bilinear combination of fermion fields, is described for the group SU(3). More details on the implementation of the substitution scheme on a computer can be found in the accompanying manual. From the effective action thus obtained in terms of meson fields and baryon fields the Green functions of the theory can be derived. As an illustrative application the effective potential determining the vacuum expectation value of the meson field is calculated. (Auth.)
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....
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...
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.)
Indirect effects in dual radiation action
International Nuclear Information System (INIS)
Zaider, M.; Rossi, H.H.
1988-01-01
The basic aim in this paper is to establish the link between indirect effects of radiation action and the spatial distribution of radicals at the time of energy deposition as well as throughout subsequent diffusion and interaction. The fact that radicals diffuse for a finite distance before damaging a biomolecule has dramatic effects on their subsequent probability to result in lesions. Thus at very low DMSO concentrations, where p = 0.5, one expects - all other things being equal - some 75% of the lesions to result from indirect or semidirect lesions. The number calculated here is lower (15%), a direct result of the fact that such lesions involve proximity functions modulated by diffusion. At higher DMSO concentrations this percentage becomes progressively smaller, as expected. It appears thus that for low-LET radiation, the relative amount of indirect damage in single tracks (also termed intratrack or single events) action is very small. By contrast, intertrack (or two-event) contributions will have the ratio between direct and (indirect + semidirect) contributions given by p 2 /(1-p 2 ). The reason for this is that sublesions from different tracks are uniformly distributed throughout the cell nucleus; their probability of interaction should not depend on any previous diffusional processes. For the example given above (p = 0.5) they do expect 65% of intertrack (two-hit) lesions to have resulted from indirect or semidirect mechanisms. This contrast between the almost exclusively direct character of intratrack lesions and the dominant role of indirect action in intertrack lesions produced by low-LET radiation is an important conclusion of this study
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.
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.
Effective action for stochastic partial differential equations
International Nuclear Information System (INIS)
Hochberg, David; Molina-Paris, Carmen; Perez-Mercader, Juan; Visser, Matt
1999-01-01
Stochastic partial differential equations (SPDEs) are the basic tool for modeling systems where noise is important. SPDEs are used for models of turbulence, pattern formation, and the structural development of the universe itself. It is reasonably well known that certain SPDEs can be manipulated to be equivalent to (nonquantum) field theories that nevertheless exhibit deep and important relationships with quantum field theory. In this paper we systematically extend these ideas: We set up a functional integral formalism and demonstrate how to extract all the one-loop physics for an arbitrary SPDE subject to arbitrary Gaussian noise. It is extremely important to realize that Gaussian noise does not imply that the field variables undergo Gaussian fluctuations, and that these nonquantum field theories are fully interacting. The limitation to one loop is not as serious as might be supposed: Experience with quantum field theories (QFTs) has taught us that one-loop physics is often quite adequate to give a good description of the salient issues. The limitation to one loop does, however, offer marked technical advantages: Because at one loop almost any field theory can be rendered finite using zeta function technology, we can sidestep the complications inherent in the Martin-Siggia-Rose formalism (the SPDE analog of the Becchi-Rouet-Stora-Tyutin formalism used in QFT) and instead focus attention on a minimalist approach that uses only the physical fields (this ''direct approach'' is the SPDE analog of canonical quantization using physical fields). After setting up the general formalism for the characteristic functional (partition function), we show how to define the effective action to all loops, and then focus on the one-loop effective action and its specialization to constant fields: the effective potential. The physical interpretation of the effective action and effective potential for SPDEs is addressed and we show that key features carry over from QFT to the case of
Effective action for stochastic partial differential equations
Energy Technology Data Exchange (ETDEWEB)
Hochberg, David [Laboratorio de Astrofisica Espacial y Fisica Fundamental, Apartado 50727, 28080 Madrid, (Spain); Centro de Astrobiologia, INTA, Carratera Ajalvir, Km. 4, 28850 Torrejon, Madrid, (Spain); Molina-Paris, Carmen [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Perez-Mercader, Juan [Laboratorio de Astrofisica Espacial y Fisica Fundamental, Apartado 50727, 28080 Madrid, (Spain); Visser, Matt [Physics Department, Washington University, Saint Louis, Missouri 63130-4899 (United States)
1999-12-01
Stochastic partial differential equations (SPDEs) are the basic tool for modeling systems where noise is important. SPDEs are used for models of turbulence, pattern formation, and the structural development of the universe itself. It is reasonably well known that certain SPDEs can be manipulated to be equivalent to (nonquantum) field theories that nevertheless exhibit deep and important relationships with quantum field theory. In this paper we systematically extend these ideas: We set up a functional integral formalism and demonstrate how to extract all the one-loop physics for an arbitrary SPDE subject to arbitrary Gaussian noise. It is extremely important to realize that Gaussian noise does not imply that the field variables undergo Gaussian fluctuations, and that these nonquantum field theories are fully interacting. The limitation to one loop is not as serious as might be supposed: Experience with quantum field theories (QFTs) has taught us that one-loop physics is often quite adequate to give a good description of the salient issues. The limitation to one loop does, however, offer marked technical advantages: Because at one loop almost any field theory can be rendered finite using zeta function technology, we can sidestep the complications inherent in the Martin-Siggia-Rose formalism (the SPDE analog of the Becchi-Rouet-Stora-Tyutin formalism used in QFT) and instead focus attention on a minimalist approach that uses only the physical fields (this ''direct approach'' is the SPDE analog of canonical quantization using physical fields). After setting up the general formalism for the characteristic functional (partition function), we show how to define the effective action to all loops, and then focus on the one-loop effective action and its specialization to constant fields: the effective potential. The physical interpretation of the effective action and effective potential for SPDEs is addressed and we show that key features carry over from
Semiclassical strings in Sasaki-Einstein manifolds and long operators in N = 1 gauge theories
International Nuclear Information System (INIS)
Benvenuti, Sergio; Kruczenski, Martin
2006-01-01
We study the AdS/CFT relation between an infinite class of 5-d Y p,q Sasaki-Einstein metrics and the corresponding quiver theories. The long BPS operators of the field theories are matched to massless geodesics in the geometries, providing a test of AdS/CFT for these cases. Certain small fluctuations (in the BMN sense) can also be successfully compared. We then go further and find, using an appropriate limit, a reduced action, first order in time derivatives, which describes strings with large R-charge. In the field theory we consider holomorphic operators with large winding numbers around the quiver and find, interestingly, that, after certain simplifying assumptions, they can be described effectively as strings moving in a particular metric. Although not equal, the metric is similar to the one in the bulk. We find it encouraging that a string picture emerges directly from the field theory and discuss possible ways to improve the agreement
Highly excited strings I: Generating function
Directory of Open Access Journals (Sweden)
Dimitri P. Skliros
2017-03-01
Full Text Available This is the first of a series of detailed papers on string amplitudes with highly excited strings (HES. In the present paper we construct a generating function for string amplitudes with generic HES vertex operators using a fixed-loop momentum formalism. We generalise the proof of the chiral splitting theorem of D'Hoker and Phong to string amplitudes with arbitrary HES vertex operators (with generic KK and winding charges, polarisation tensors and oscillators in general toroidal compactifications E=RD−1,1×TDcr−D (with generic constant Kähler and complex structure target space moduli, background Kaluza–Klein (KK gauge fields and torsion. We adopt a novel approach that does not rely on a “reverse engineering” method to make explicit the loop momenta, thus avoiding a certain ambiguity pointed out in a recent paper by Sen, while also keeping the genus of the worldsheet generic. This approach will also be useful in discussions of quantum gravity and in particular in relation to black holes in string theory, non-locality and breakdown of local effective field theory, as well as in discussions of cosmic superstrings and their phenomenological relevance. We also discuss the manifestation of wave/particle (or rather wave/string duality in string theory.
Hard scattering and gauge/string duality
International Nuclear Information System (INIS)
Polchinski, Joseph; Strassler, Matthew J.
2002-01-01
We consider high-energy fixed-angle scattering of glueballs in confining gauge theories that have supergravity duals. Although the effective description is in terms of the scattering of strings, we find that the amplitudes are hard (power law). This is a consequence of the warped geometry of the dual theory, which has the effect that in an inertial frame the string process is never in the soft regime. At small angle we find hard and Regge behaviors in different kinematic regions
Varying dilaton as a tracer of classical string interactions
Dodelson, Matthew; Silverstein, Eva; Torroba, Gonzalo
2017-09-01
We analyze tree-level string amplitudes in a linear dilaton background, motivated by its use as a gauge-invariant tracer of string interactions in scattering experiments and its genericity among simple perturbative string theory limits. A simple case is given by a lightlike dependence for the dilaton. The zero mode of the embedding coordinate in the direction of dilaton variation requires special care. Employing Gaussian wave packets and a well-defined modification of the dilaton profile far from the dominant interaction region, we obtain finite results which explicitly reproduce the interaction time scales expected from joining and splitting interactions involving oscillating strings in simple string scattering processes. There is an interesting interplay between the effects of the linear dilaton and the i ɛ prescription. In more general circumstances this provides a method for tracing the degree of nonlocality in string interactions, and it gives a basis for further studies of perturbative supercritical string theory at higher loop order.
Closed string tachyon driving f(R) cosmology
Wang, Peng; Wu, Houwen; Yang, Haitang
2018-05-01
To study quantum effects on the bulk tachyon dynamics, we replace R with f(R) in the low-energy effective action that couples gravity, the dilaton, and the bulk closed string tachyon of bosonic closed string theory and study properties of their classical solutions. The α' corrections of the graviton-dilaton-tachyon system are implemented in the f(R). We obtain the tachyon-induced rolling solutions and show that the string metric does not need to remain fixed in some cases. In the case with H( t=‑∞ ) = , only the R and R2 terms in f(R) play a role in obtaining the rolling solutions with nontrivial metric. The singular behavior of more classical solutions are investigated and found to be modified by quantum effects. In particular, there could exist some classical solutions, in which the tachyon field rolls down from a maximum of the tachyon potential while the dilaton expectation value is always bounded from above during the rolling process.
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
The Universal One-Loop Effective Action
Drozd, Aleksandra; Quevillon, Jérémie; You, Tevong
2016-01-01
We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.
The universal one-loop effective action
International Nuclear Information System (INIS)
Drozd, Aleksandra; Ellis, John; Quevillon, Jérémie; You, Tevong
2016-01-01
We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.
Casimir energy of rotating string - indirect approach
Energy Technology Data Exchange (ETDEWEB)
Hadasz, L. [Smoluchowski Institute of Physics, Jagiellonian University, Cracow (Poland)
1999-04-01
Methods of calculating the Casimir energy which do not require the explicit knowledge of the oscillation frequencies are developed and applied to the model of the Nambu-Goto string with the Gauss-Bonnet term in the action. (author) 17 refs, 1 fig
Physical Fock space of tensionless strings
Antoniadis, Ignatios; Antoniadis, Ignatios; Savvidy, George
2004-01-01
We study the physical Fock space of the tensionless string theory with perimeter action which has pure massless spectrum. The states are classified by the Wigner's little group for massless particles. The ground state contains infinite many massless fields of fixed helicity, the excitation levels realize CSR representations. We demonstrate that the first and the second excitation levels are physical null states.
Ground State Energy of the Modified Nambu-Goto String
Hadasz, Leszek
We calculate, using zeta function regularization method, semiclassical energy of the Nambu-Goto string supplemented with the boundary, Gauss-Bonnet term in the action and discuss the tachyonic ground state problem.
Ground state energy of the modified Nambu-Goto string
Hadasz, Leszek
1997-01-01
We calculate, using zeta function regularization method, semiclassical energy of the Nambu-Goto string supplemented with the boundary, Gauss-Bonnet term in the action and discuss the tachyonic ground state problem.
International Nuclear Information System (INIS)
Randjbar-Daemi, S.
1987-01-01
The propagation of closed bosonic strings interacting with background gravitational and dilaton fields is reviewed. The string is treated as a quantum field theory on a compact 2-dimensional manifold. The question is posed as to how the conditions for the vanishing trace anomaly and the ensuing background field equations may depend on global features of the manifold. It is shown that to the leading order in σ-model perturbation theory the string loop effects do not modify the gravitational and the dilaton field equations. However for the purely bosonic strings new terms involving the modular parameter of the world sheet are induced by quantum effects which can be absorbed into a re-definition of the background fields. The authors also discuss some aspects of several regularization schemes such as dimensional, Pauli-Villars and the proper-time cut off in an appendix
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.)
Non critical super string amplitudes in more than two dimensions
International Nuclear Information System (INIS)
Foerste, S.
1993-01-01
Neveu-Schwarz string theory is coupled to two dimensional gravity which contains besides the anomaly induced Liouville action the Jackiw-Teitelboim action describing pure 2D super gravity. Considering correlation functions we obtain a trivial KPZ relation. As possible interpretations we discuss a d + 2-dimensional critical string picture as well as a four dimensional non critical one. It turns out that a GSO projection is possible. (orig.)
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
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.
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)
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
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.)
Quantum string test of nonconformal holography
Energy Technology Data Exchange (ETDEWEB)
Chen-Lin, Xinyi; Medina-Rincon, Daniel; Zarembo, Konstantin [Nordita, Stockholm University and KTH Royal Institute of Technology,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden); Department of Physics and Astronomy, Uppsala University,SE-751 08 Uppsala (Sweden)
2017-04-18
We compute Lüscher corrections to the effective string tension in the Pilch-Warner background, holographically dual to N=2{sup ∗} supersymmetric Yang-Mills theory. The same quantity can be calculated directly from field theory by solving the localization matrix model at large-N. We find complete agreement between the field-theory predictions and explicit string-theory calculation at strong coupling.
Towards natural inflation in string theory
International Nuclear Information System (INIS)
Ben-Dayan, Ido; Pedro, Francisco G.; Westphal, Alexander
2014-07-01
We provide type IIB string embeddings of two axion variants of natural inflation. We use a combination of RR 2 form axions as the inflaton field and have its potential generated by non perturbative effects in the superpotential. Besides giving rise to inflation, the models developed take into account the stabilization of the compact space, both in the KKLT and large volume scenario regimes, an essential condition for any semi-realistic model of string inflation.
Butterfly tachyons in vacuum string field theory
International Nuclear Information System (INIS)
Matlock, Peter
2003-01-01
We use geometrical conformal field theory methods to investigate tachyon fluctuations about the butterfly projector state in vacuum string field theory. We find that the on-shell condition for the tachyon field is equivalent to the requirement that the quadratic term in the string-field action vanish on shell. This further motivates the interpretation of the butterfly state as a D-brane. We begin a calculation of the tension of the butterfly, and conjecture that this will match the case of the sliver and further strengthen this interpretation
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)
Open string T-duality in a weakly curved background
International Nuclear Information System (INIS)
Davidovic, Ljubica
2016-01-01
We consider a theory of an open string moving in a weakly curved background, composed of a constant metric and a linearly coordinate dependent Kalb-Ramond field with an infinitesimal field strength. We find its T-dual using the generalized Buscher procedure developed for the closed string moving in a weakly curved background, and the fact that solving the boundary conditions, the open string theory transforms to the effective closed string theory. So, T-dualizing the effective theory along all effective directions we obtain its T-dual theory and resume the open string theory which has such an effective theory. In this way we obtain the open string theory T-dual. (orig.)
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.)
International conference on string theory
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.
Macroscopic constraints on string unification
International Nuclear Information System (INIS)
Taylor, T.R.
1989-03-01
The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs
Phenomenological Hints from a Class of String Motivated Model Constructions
Directory of Open Access Journals (Sweden)
Hans Peter Nilles
2015-01-01
Full Text Available We use string theory constructions towards the generalisation of the supersymmetric standard model of strong and electroweak interactions. Properties of the models depend crucially on the location of fields in extradimensional compact space. This allows us to extract some generic lessons for the phenomenological properties of the low energy effective action. Within this scheme we present a compelling model based on local grand unification and mirage mediation of supersymmetry breakdown. We analyse the properties of the specific model towards its possible tests at the LHC and the complementarity to direct dark matter searches.
A premier analysis of supersymmetric closed string tachyon cosmology
Vázquez-Báez, V.; Ramírez, C.
2018-04-01
From a previously found worldline supersymmetric formulation for the effective action of the closed string tachyon in a FRW background, the Hamiltonian of the theory is constructed, by means of the Dirac procedure, and written in a quantum version. Using the supersymmetry algebra we are able to find solutions to the Wheeler-DeWitt equation via a more simple set of first order differential equations. Finally, for the k = 0 case, we compute the expectation value of the scale factor with a suitably potential also favored in the present literature. We give some interpretations of the results and state future work lines on this matter.
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.
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
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.)
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.
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
String theory compactifications
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.
International Nuclear Information System (INIS)
Ketov, S.V.
1994-09-01
Possible ways of constructing extended fermionic strings with N=4 world-sheet supersymmetry are reviewed. String theory constraints form, in general, a non-linear quasi(super)conformal algebra, and can have conformal dimensions ≥1. When N=4, the most general N=4 quasi-superconformal algebra to consider for string theory building is D(1, 2; α), whose linearisation is the so-called ''large'' N=4 superconformal algebra. The D(1, 2; α) algebra has su(2)sub(κ + )+su(2)sub(κ - )+u(1) Kac-Moody component, and α=κ - /κ + . We check the Jacobi identities and construct a BRST charge for the D(1, 2; α) algebra. The quantum BRST operator can be made nilpotent only when κ + =κ - =-2. The D(1, 2; 1) algebra is actually isomorphic to the SO(4)-based Bershadsky-Knizhnik non-linear quasi-superconformal algebra. We argue about the existence of a string theory associated with the latter, and propose the (non-covariant) hamiltonian action for this new N=4 string theory. Our results imply the existence of two different N=4 fermionic string theories: the old one based on the ''small'' linear N=4 superconformal algebra and having the total ghost central charge c gh =+12, and the new one with non-linearly realised N=4 supersymmetry, based on the SO(4) quasi-superconformal algebra and having c gh =+6. Both critical string theories have negative ''critical dimensions'' and do not admit unitary matter representations. (orig.)
Optimization of SAGD wellbore completions : short production tubing string sensitivities
Energy Technology Data Exchange (ETDEWEB)
Cokar, M.; Graham, J. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Petro-Canada, Calgary, AB (Canada)
2008-10-15
This study investigated the effects of changing the landing position of short production tubing strings near the heel of steam assisted gravity drainage (SAGD) production wells. A homogenous discretized wellbore model was used to model the reservoir and wellbore simultaneously in order to study wellbore and reservoir interactions. The aim of the study was to develop a method of optimizing bitumen production and determining the most economical position for wellbore strings. Simulations were conducted to examine the effect of shortening the production tubing string and examine the impact of extending the tubing string beyond the heel of the well on bitumen bitumen production rates and the steam oil ratio (SOR). Results of the study showed that a shortened string decreased bitumen production rates, while the amounts of steam produced through the tubing string increased. When the tubing string was extended past the heel of the well, bitumen production rates remained the same, but steam injection rates and SOR decreased. A lower pressure differential between the injector and producer wells was also observed. The study showed that SAGD producers can re-position production tubing strings in order to determine ratios of liquid production. It was concluded that although placing the short production tubing string close to the heel increased oil production, a longer tubing string improved production rates while lowering operating costs. 3 refs., 3 tabs., 35 figs.
One-loop effective action for non-local modified Gauss-Bonnet gravity in de Sitter space
Energy Technology Data Exchange (ETDEWEB)
Cognola, Guido; Zerbini, Sergio [Universita di Trento (Italy); Istituto Nazionale di Fisica Nucleare Gruppo Collegato di Trento, Dipartimento di Fisica, Trento (Italy); Elizalde, Emilio [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Odintsov, Sergei D. [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); ICREA, Barcelona (Spain); TSPU, Center of Theor. Phys., Tomsk (Russian Federation)
2009-12-15
We discuss the classical and quantum properties of non-local modified Gauss-Bonnet gravity in de Sitter space, using its equivalent representation via string-inspired local scalar-Gauss-Bonnet gravity with a scalar potential. A classical, multiple de Sitter universe solution is found where one of the de Sitter phases corresponds to the primordial inflationary epoch, while the other de Sitter space solution - the one with the smallest Hubble rate - describes the late-time acceleration of our universe. A Chameleon scenario for the theory under investigation is developed, and it is successfully used to show that the theory complies with gravitational tests. An explicit expression for the one-loop effective action for this non-local modified Gauss-Bonnet gravity in the de Sitter space is obtained. It is argued that this effective action might be an important step towards the solution of the cosmological constant problem. (orig.)
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
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.)
Confusing the heterotic string
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.
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.
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
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.)
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.
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.
Does string theory lead to extended inflation?
Campbell, Bruce A.; Linde, Andrei; Olive, Keith A.
1991-05-01
We consider the relationship between string theory and currently proposed models of extended inflation. In doing so, we discuss the conformal actions in string theory and in Jordan-Brans-Dicke gravity. We show explicitly the equivalence of pictures in which either gauge or gravitational couplings are changing with time. We demonstrate that the existence of the dilation in string theory does not naturally lead to extended inflation as currently discussed. We also discuss the resolution of the graceful exit problem of old inflation in Einstein gravity using either power-law inflation, or exponential inflation with a changing bubble formation rate. On leave of absence from School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.
Effects of BDNF polymorphisms on antidepressant action.
Tsai, Shih-Jen; Hong, Chen-Jee; Liou, Ying-Jay
2010-12-01
Evidence suggests that the down-regulation of the signaling pathway involving brain-derived neurotrophic factor (BDNF), a molecular element known to regulate neuronal plasticity and survival, plays an important role in the pathogenesis of major depression. The restoration of BDNF activity induced by antidepressant treatment has been implicated in the antidepressant therapeutic mechanism. Because there is variability among patients with major depressive disorder in terms of response to antidepressant treatment and since genetic factors may contribute to this inter-individual variability in antidepressant response, pharmacogenetic studies have tested the associations between genetic polymorphisms in candidate genes related to antidepressant therapeutic action. In human BDNF gene, there is a common functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF. Because of the potentially important role of BDNF in the antidepressant mechanism, many pharmacogenetic studies have tested the association between this polymorphism and the antidepressant therapeutic response, but they have produced inconsistent results. A recent meta-analysis of eight studies, which included data from 1,115 subjects, suggested that the Val/Met carriers have increased antidepressant response in comparison to Val/Val homozygotes, particularly in the Asian population. The positive molecular heterosis effect (subjects heterozygous for a specific genetic polymorphism show a significantly greater effect) is compatible with animal studies showing that, although BDNF exerts an antidepressant effect, too much BDNF may have a detrimental effect on mood. Several recommendations are proposed for future antidepressant pharmacogenetic studies of BDNF, including the consideration of multiple polymorphisms and a haplotype approach, gene-gene interaction, a single antidepressant regimen, controlling for age and gender interactions, and pharmacogenetic
The ξ/ξ2nd ratio as a test for Effective Polyakov Loop Actions
Caselle, Michele; Nada, Alessandro
2018-03-01
Effective Polyakov line actions are a powerful tool to study the finite temperature behaviour of lattice gauge theories. They are much simpler to simulate than the original (3+1) dimensional LGTs and are affected by a milder sign problem. However it is not clear to which extent they really capture the rich spectrum of the original theories, a feature which is instead of great importance if one aims to address the sign problem. We propose here a simple way to address this issue based on the so called second moment correlation length ξ2nd. The ratio ξ/ξ2nd between the exponential correlation length and the second moment one is equal to 1 if only a single mass is present in the spectrum, and becomes larger and larger as the complexity of the spectrum increases. Since both ξexp and ξ2nd are easy to measure on the lattice, this is an economic and effective way to keep track of the spectrum of the theory. In this respect we show using both numerical simulation and effective string calculations that this ratio increases dramatically as the temperature decreases. This non-trivial behaviour should be reproduced by the Polyakov loop effective action.
Cosmic strings in unified gauge theories
International Nuclear Information System (INIS)
Everett, A.E.
1981-01-01
Some spontaneously broken gauge theories can give rise to stringlike vacuum structures (vortices). It has been pointed out by Vilenkin that in grand unified theories these can be sufficiently massive to have cosmological implications, e.g., in explaining the formation of galaxies. The circumstances in which such structures occur are examined. They do not occur in the simplest grand unified theories, but can occur in some more elaborate models which have been proposed. The cross section for the scattering of elementary particles by strings is estimated. This is used to evaluate the effect of collisions on the dynamics of a collapsing circular string, with particular attention to the question of whether energy dissipation by collision can reduce the rate of formation of black holes by collapsed strings, which may be unacceptably large in models where strings occur. It is found that the effect of collisions is not important in the case of grand unified strings, although it can be important for lighter strings
String pair production in non homogeneous backgrounds
Energy Technology Data Exchange (ETDEWEB)
Bolognesi, S. [Department of Physics “E. Fermi” University of Pisa, and INFN - Sezione di Pisa,Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Rabinovici, E. [Racah Institute of Physics, The Hebrew University of Jerusalem,91904 Jerusalem (Israel); Tallarita, G. [Departamento de Ciencias, Facultad de Artes Liberales,Universidad Adolfo Ibáñez, Santiago 7941169 (Chile)
2016-04-28
We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.
String pair production in non homogeneous backgrounds
International Nuclear Information System (INIS)
Bolognesi, S.; Rabinovici, E.; Tallarita, G.
2016-01-01
We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.
Wong's equations and the small x effective action in QCD
International Nuclear Information System (INIS)
Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju
2001-01-01
We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong's equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the action may be particularly useful in computing next-to-leading-order results in QCD at small x
Wong's equations and the small x effective action in QCD
International Nuclear Information System (INIS)
Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju
2000-01-01
We propose a new form for the small x effective action in QCD. This form of the effective action is motivated by Wong's equations for classical, colored particles in non-Abelian background fields. We show that the BFKL equation, which sums leading logarithms in x, is efficiently reproduced with this form of the action. We argue that this form of the action may be particularly useful in computing next-to-leading-order results in QCD at small x
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.
Developing the covariant Batalin-Vilkovisky approach to string theory
International Nuclear Information System (INIS)
Hata, H.; Zwiebach, B.
1994-01-01
In this work the authors investigate the variation of the string field action under changes of the string field vertices giving rise to different decompositions of the moduli spaces of Riemann surfaces. The authors establish that any such change in the string action arises from a field transformation canonical with respect to the Batalin-Vilkovisky (BV) antibracket and find the explicit form of the generator of the infinitesimal transformations. Two theories using different decompositions of moduli space are shown to yield the same gauge-fixed action upon use of different gauge-fixing conditions. The authors also elaborate on recent work on the covariant BV formalism, and emphasize the necessity of a measure in the space of two-dimensional field theories in order to extend a recent analysis of background independence to quantum string field theory. 22 refs., 2 figs
Effective Gravitational Theories in String Theory and the AdS/CFT Correspondence
DEFF Research Database (Denmark)
Pedersen, Andreas Vigand
an effective theory for higher dimensional extended black holes in a uid/elastic perturbative derivative expansion. Moreover, we show that the approach is quite universal and can be extended to various supergravities. Finally, we consider a new generalization of the method, which allows us to treat (SUGRA...... as low/high spin. As a byproduct of our analysis, we find a new stationary dipole-charged black hole solution on the AdS S backgrounds of type IIB/M-theory. We finally consider, via a double scaling extremal limit, a novel null-wave zero-temperature giant graviton exhibiting a BPS spectrum. Finally......We consider various aspects of effective gravitational theories, including supergravity, within the framework of the blackfold approach. The thesis is naturally split into three parts. In the first part of the thesis, we explore the blackfold approach and explain how it is possible to write down...
D-brane black holes: Large-N limit and the effective string description
Energy Technology Data Exchange (ETDEWEB)
Hassan, S F [International Centre for Theoretical Physics, Trieste (Italy); Wadia, S R [Theoretical Physics Div., CERN, Geneva (Switzerland)
1997-03-01
We address the derivation of the effective conformal field theory description of the 5-dimensional black hole, modelled by a collection of D1-and D5-branes, from the corresponding low energy U(Q{sub 1}) x U(Q{sub 5}) gauge theory. Finite horizon size at weak coupling requires both Q{sub 1} and Q{sub 5} to be large. We derive the results in the moduli space approximation (say for Q{sub 1} > Q{sub 5}) and appeal to supersymmetry to argue its validity beyond weak coupling. As a result of a combination of quenched Z{sub Q1} Wilson lines and a residual Weyl symmetry, the low-lying excitations of the U(Q{sub 1}) x U(Q{sub 5}) gauge theory are described by an effective N = 4 superconformal field theory with c = 6 in 1 + 1 dimensions, where the space is a circle of radius RQ{sub 1}Q{sub 5}. We also discuss the appearance of a marginal perturbation of the effective conformal field theory for large but finite values of Q{sub 5}. (author). 42 refs.
International Nuclear Information System (INIS)
Kaku, M.
1988-01-01
We present an entirely new approach to closed-string field theory, called Igeometric string field theory R, which avoids the complications found in Becchi-Rouet-Stora-Tyutin string field theory (e.g., ghost counting, infinite overcounting of diagrams, midpoints, lack of modular invariance). Following the analogy with general relativity and Yang-Mills theory, we define a new infinite-dimensional local gauge group, called the unified string group, which uniquely specifies the connection fields, the curvature tensor, the measure and tensor calculus, and finally the action itself. Geometric field theory, when gauge fixed, yields an entirely new class of gauges called the interpolating gauge which allows us to smoothly interpolate between the midpoint gauge and the end-point gauge (''covariantized light-cone gauge''). We can show that geometric string field theory reproduces one copy of the Shapiro-Virasoro model. Surprisingly, after the gauge is broken, a new Iclosed four-string interactionR emerges as the counterpart of the instantaneous four-fermion Coulomb term in QED. This term restores modular invariance and precisely fills the missing region of the complex plane
Electron string phenomenon: physics and use
Donets, Evgeny D.
2004-01-01
Electron string phenomenon arises as a result of phase transition of a state of multiply reflected electron beam to this new discovered state of one component electron plasma and can be easily observed in the reflex mode of EBIS operation. The transition goes via a strong instability, which causes considerable electron energy spread, which in its turn suppresses the instability. Electron string state is a stationary state of hot pure electron plasma, which is heated by injected electron beam and cooled because of electron loses. Electron string is quiet in broad regions of experimental parameters, so that it is used for confinement and ionization of positive ions by electron impact to highly charge states similar to electron beams in EBIS. Application of electron strings instead of electron beams for ion production allows to save about 99% of electric power of electron beam and simultaneously to improve reliability of an ion source considerably. The JINR EBIS `Krion-2' in the string mode of operation is used for production of N7+, Ar16+ and Fe24+ ion beams and their acceleration to relativistic energies on the facility of the JINR super conducting one turn injection synchrotron `Nuklotron'. The tubular electron string possibly can exist and it is under study now theoretically and experiments are prepared now. Estimations show that a Tubular Electron String Ion Source (TESIS) could have up to three orders of magnitude higher ion output then a Linear one (LESIS). In frames of nuclear astrophysics electron strings can be used for research of fusion nuclear reactions at low energies in conditions when both beam and target nuclei do not carry orbital electrons. The project NARITA — Nuclear Astrophysics Researches in an Ion Trap Apparatus is proposed. Polarization effects also can be studied.
Electron string phenomenon: physics and use
International Nuclear Information System (INIS)
Donets, Evgeny D
2004-01-01
Electron string phenomenon arises as a result of phase transition of a state of multiply reflected electron beam to this new discovered state of one component electron plasma and can be easily observed in the reflex mode of EBIS operation. The transition goes via a strong instability, which causes considerable electron energy spread, which in its turn suppresses the instability. Electron string state is a stationary state of hot pure electron plasma, which is heated by injected electron beam and cooled because of electron loses. Electron string is quiet in broad regions of experimental parameters, so that it is used for confinement and ionization of positive ions by electron impact to highly charge states similar to electron beams in EBIS. Application of electron strings instead of electron beams for ion production allows to save about 99% of electric power of electron beam and simultaneously to improve reliability of an ion source considerably. The JINR EBIS 'Krion-2' in the string mode of operation is used for production of N 7+ , Ar 16+ and Fe 24+ ion beams and their acceleration to relativistic energies on the facility of the JINR super conducting one turn injection synchrotron 'Nuklotron'. The tubular electron string possibly can exist and it is under study now theoretically and experiments are prepared now. Estimations show that a Tubular Electron String Ion Source (TESIS) could have up to three orders of magnitude higher ion output then a Linear one (LESIS). In frames of nuclear astrophysics electron strings can be used for research of fusion nuclear reactions at low energies in conditions when both beam and target nuclei do not carry orbital electrons. The project NARITA - Nuclear Astrophysics Researches in an Ion Trap Apparatus is proposed. Polarization effects also can be studied
Coordinate and Kaehler σ-model anomalies and their cancellation in string effective field theories
International Nuclear Information System (INIS)
Lopes Cardoso, G.; Ovrut, B.A.
1993-01-01
We discuss the complete set of one-loop triangle graphs involving the Yang-Mills gauge connection, the Kaehler connection and the σ-model coordinate connection in the effective field theory of (2, 2) symmetric Z N orbifolds. That is, we discuss pure gauge, pure Kaehler and pure σ-model coordinate anomalies as well as the mixed anomalies, such as Kaehler-gauge, some of which have been discussed elsewhere. We propose a mechanism for restoring both Kaehler and σ-model coordinate symmetry based upon the introduction of two types of counterterms. Finally, we enlarge σ-model generalization of the Green-Schwarz mechanism to allow the removal of the universal parts of a wider class of anomalies than those previously discussed. (orig.)
Transplanckian censorship and global cosmic strings
International Nuclear Information System (INIS)
Dolan, Matthew J.; Draper, Patrick; Kozaczuk, Jonathan; Patel, Hiren
2017-01-01
Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections between various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants f
Transplanckian censorship and global cosmic strings
Dolan, Matthew J.; Draper, Patrick; Kozaczuk, Jonathan; Patel, Hiren
2017-04-01
Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections be-tween various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants f M p /f , the EFT is under control and the string cores undergo topological inflation, which may be either of exponential or power-law type. We show that the exterior spacetime is nonsingular and equivalent to a decompactifying cigar geometry, with the radion rolling in a potential generated by axion flux. Signals are able to circumnavigate infinite straight strings in finite but exponentially long time, t ˜ e Δ a/ M p . For finite loops of supercritical string in asymptotically flat space, we argue that if topological inflation occurs, then topological censorship implies transplanckian censorship, or that external observers are forbidden from threading the loop and observing the full excursion of the axion.
Transplanckian censorship and global cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Dolan, Matthew J. [ARC Centre of Excellence for Particle Physics at the Terascale,School of Physics, University of Melbourne,Melbourne, 3010 (Australia); Draper, Patrick; Kozaczuk, Jonathan; Patel, Hiren [Amherst Center for Fundamental Interactions, Department of Physics,University of Massachusetts,Amherst, MA 01003 (United States)
2017-04-21
Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections between various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants f
D-string fluid in conifold, I: Topological gauge model
International Nuclear Information System (INIS)
Ahl Laamara, R.; Drissi, L.B.; Saidi, E.H.
2006-01-01
Motivated by similarities between quantum Hall systems a la Susskind and aspects of topological string theory on conifold as well as results obtained in [E.H. Saidi, Topological SL(2) gauge theory on conifold and noncommutative geometry, hep-th/0601020], we study the dynamics of D-string fluids running in deformed conifold in presence of a strong and constant RR background B-field. We first introduce the basis of D-string system in fluid approximation and then derive the holomorphic noncommutative gauge invariant field action describing its dynamics in conifold. This study may be also viewed as embedding Susskind description for Laughlin liquid in type IIB string theory. FQH systems on real manifolds RxS 2 and S 3 are shown to be recovered by restricting conifold to its Lagrangian sub-manifolds. Aspects of quantum behaviour of the string fluid are discussed. ring fluid are discussed
Gauge coupling unification in realistic free-fermionic string models
International Nuclear Information System (INIS)
Dienes, K.R.; Faraggi, A.E.
1995-01-01
We discuss the unification of gauge couplings within the framework of a wide class of realistic free-fermionic string models which have appeared in the literature, including the flipped SU(5), SO(6)xSO(4), and various SU(3)xSU(2)xU(1) models. If the matter spectrum below the string scale is that of the Minimal Supersymmetric Standard Model (MSSM), then string unification is in disagreement with experiment. We therefore examine several effects that may modify the minimal string predictions. First, we develop a systematic procedure for evaluating the one-loop heavy string threshold corrections in free-fermionic string models, and we explicitly evaluate these corrections for each of the realistic models. We find that these string threshold corrections are small, and we provide general arguments explaining why such threshold corrections are suppressed in string theory. Thus heavy thresholds cannot resolve the disagreement with experiment. We also study the effect of non-standard hypercharge normalizations, light SUSY thresholds, and intermediate-scale gauge structure, and similarly conclude that these effects cannot resolve the disagreement with low-energy data. Finally, we examine the effects of additional color triplets and electroweak doublets beyond the MSSM. Although not required in ordinary grand unification scenarios, such states generically appear within the context of certain realistic free-fermionic string models. We show that if these states exist at the appropriate thresholds, then the gauge couplings will indeed unify at the string scale. Thus, within these string models, string unification can be in agreement with low-energy data. (orig.)
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...
High-energy string-brane scattering: leading eikonal and beyond
D'Appollonio, Giuseppe; Russo, Rodolfo; Veneziano, Gabriele
2010-01-01
We extend previous techniques for calculations of transplanckian-energy string-string collisions to the high-energy scattering of massless closed strings from a stack of N Dp-branes in Minkowski spacetime. We show that an effective non-trivial metric emerges from the string scattering amplitudes by comparing them against the semiclassical dynamics of high-energy strings in the extremal p-brane background. By changing the energy, impact parameter and effective open string coupling, we are able to explore various interesting regimes and to reproduce classical expectations, including tidal-force excitations, even beyond the leading-eikonal approximation.
Effects of social intention on movement kinematics in cooperative actions
Directory of Open Access Journals (Sweden)
Francois eQuesque
2013-10-01
Full Text Available Optimal control models of biological movements are used to account for those internal variables that constrain voluntary goal-directed actions. They however do not take into account external environmental constraints as those associated to social intention. We investigated here the effects of the social context on kinematic characteristics of sequential actions consisting in placing an object on an initial pad (preparatory action before reaching and grasping as fast as possible the object to move it to another location (main action. Reach-to-grasp actions were performed either in an isolated condition or in the presence of a partner (audience effect, located in the near or far space (effect of shared reachable space, and who could intervene on the object in a systematic fashion (effect of social intention effect or not (effect of social uncertainty. Results showed an absence of audience effect but nevertheless an influence of the social context both on the main and the preparatory actions. In particular, a localized effect of shared reachable space was observed on the main action, which was smoother when performed within the reachable space of the partner. Furthermore, a global effect of social uncertainty was observed on both actions with faster and jerkier movements. Finally, social intention affected the preparatory action with higher wrist displacements and slower movements when the object was placed for the partner rather than placed for self-use. Overall, these results demonstrate specific effects of action space, social uncertainty and social intention on the planning of reach-to-grasp actions, in particular on the preparatory action, which was performed with no specific execution constraint. These findings underline the importance of considering the social context in optimal models of action control for human-robot interactions, in particular when focusing on the implementation of motor parameters required to afford intuitive
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.
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.)
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.)
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.)
Coulomb string tension, asymptotic string tension, and the gluon chain
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.
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
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
Are Stopped Strings Preferred in Sad Music?
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...
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.)
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.
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.)
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
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
Heterotic string solutions and coset conformal field theories
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...
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
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...
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
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
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
Matrix string partition function
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.
Effective climate action: why biodiversity matters | IDRC ...
International Development Research Centre (IDRC) Digital Library (Canada)
2018-05-22
May 22, 2018 ... Home · Resources · Perspectives ... This resource-dependency describes the relationship between ... involves holistic and integrated resource management strategies that ... This has been recognized in the Strategic Plan for Biodiversity ... as setting the global framework for priority actions on biodiversity.
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.)
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
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....
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.
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.
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.)
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.)
String theory in four dimensions
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.
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.
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
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
Classical open-string field theory: A∞-algebra, renormalization group and boundary states
International Nuclear Information System (INIS)
Nakatsu, Toshio
2002-01-01
We investigate classical bosonic open-string field theory from the perspective of the Wilson renormalization group of world-sheet theory. The microscopic action is identified with Witten's covariant cubic action and the short-distance cut-off scale is introduced by length of open-string strip which appears in the Schwinger representation of open-string propagator. Classical open-string field theory in the title means open-string field theory governed by a classical part of the low energy action. It is obtained by integrating out suitable tree interactions of open-strings and is of non-polynomial type. We study this theory by using the BV formalism. It turns out to be deeply related with deformation theory of A ∞ -algebra. We introduce renormalization group equation of this theory and discuss it from several aspects. It is also discussed that this theory is interpreted as a boundary open-string field theory. Closed-string BRST charge and boundary states of closed-string field theory in the presence of open-string field play important roles
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.
D-branes in little string theory
International Nuclear Information System (INIS)
Israel, Dan; Pakman, Ari; Troost, Jan
2005-01-01
We analyze in detail the D-branes in the near-horizon limit of NS5-branes on a circle, the holographic dual of little string theory in a double scaling limit. We emphasize their geometry in the background of the NS5-branes and show the relation with D-branes in coset models. The exact one-point functions giving the coupling of the closed string states with the D-branes and the spectrum of open strings are computed. Using these results, we analyze several aspects of Hanany-Witten setups, using exact CFT analysis. In particular we identify the open string spectrum on the D-branes stretched between NS5-branes which confirms the low-energy analysis in brane constructions, and that allows to go to higher energy scales. As an application we show the emergence of the beta-function of the N=2 gauge theory on D4-branes stretching between NS5-branes from the boundary states describing the D4-branes. We also speculate on the possibility of getting a matrix model description of little string theory from the effective theory on the D1-branes. By considering D3-branes orthogonal to the NS5-branes we find a CFT incarnation of the Hanany-Witten effect of anomalous creation of D-branes. Finally we give an brief description of some non-BPS D-branes
Straight-line string with curvature
International Nuclear Information System (INIS)
Solov'ev, L.D.
1995-01-01
Classical and quantum solutions for the relativistic straight-line string with arbitrary dependence on the world surface curvature are obtained. They differ from the case of the usual Nambu-Goto interaction by the behaviour of the Regge trajectory which in general can be non-linear. A regularization of the action is considered and a comparison with relativistic point with curvature is made. 5 refs
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
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)
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.
On exceptional instanton strings
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
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
Non-topological non-commutativity in string theory
International Nuclear Information System (INIS)
Guttenberg, S.; Herbst, M.; Kreuzer, M.; Rashkov, R.
2008-01-01
Quantization of coordinates leads to the non-commutative product of deformation quantization, but is also at the roots of string theory, for which space-time coordinates become the dynamical fields of a two-dimensional conformal quantum field theory. Appositely, open string diagrams provided the inspiration for Kontsevich's solution of the long-standing problem of quantization of Poisson geometry by virtue of his formality theorem. In the context of D-brane physics non-commutativity is not limited, however, to the topological sector. We show that non-commutative effective actions still make sense when associativity is lost and establish a generalized Connes-Flato-Sternheimer condition through second order in a derivative expansion. The measure in general curved backgrounds is naturally provided by the Born-Infeld action and reduces to the symplectic measure in the topological limit, but remains non-singular even for degenerate Poisson structures. Analogous superspace deformations by RR-fields are also discussed. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
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)
Macroscopic fundamental strings in cosmology
Energy Technology Data Exchange (ETDEWEB)
Aharonov, Y; Englert, F; Orloff, J
1987-12-24
We show that, when D greater than or equal to 4, theories of closed strings of closed strings in D, non-compact space-time dimensions exhibit a phase transition. The high-temperature phase is characterized by a condensate of arbitrarily long strings with Hausdorff dimension two (area filling curves). We suggest that this stringy phase is the ancestor of the adiabatic era. Fundamental strings could then both drive the inflation and seed, in a way reminiscent of the cosmic string mechanism, the large structures in the universe.
Strings as perturbations of evolving spin networks
International Nuclear Information System (INIS)
Smolin, Lee
2000-01-01
One step in the construction of a background independent formulation of string theory is detailed, in which it is shown how perturbative strings may arise as small fluctuations around histories in a formulation of non-perturbative dynamics of spin networks due to Markopoulou. In this formulation the dynamics of spin network states and their generalizations is described in terms of histories which have discrete analogues of the causal structure and many fingered time of Lorentzian spacetimes. Perturbations of these histories turn out to be described in terms of spin systems defined on 2-dimensional timelike surfaces embedded in the discrete spacetime. When the history has a classical limit which is Minkowski spacetime, the action of the perturbation theory is given to leading order by the spacetime area of the surface, as in bosonic string theory. This map between a non-perturbative formulation of quantum gravity and a 1+1 dimensional theory generalizes to a large class of theories in which the group SU(2) i s extended to any quantum group or supergroup. It is argued that a necessary condition for the non-perturbative theory to have a good classical limit is that the resulting 1+1 dimensional theory defines a consistent and stable perturbative string theory
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
Strings draw theorists together
Energy Technology Data Exchange (ETDEWEB)
Green, Michael [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge (United Kingdom)
2000-03-01
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{sup -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
Covariant effective action for loop quantum cosmology from order reduction
International Nuclear Information System (INIS)
Sotiriou, Thomas P.
2009-01-01
Loop quantum cosmology (LQC) seems to be predicting modified effective Friedmann equations without extra degrees of freedom. A puzzle arises if one decides to seek for a covariant effective action which would lead to the given Friedmann equation: The Einstein-Hilbert action is the only action that leads to second order field equations and, hence, there exists no covariant action which, under metric variation, leads to a modified Friedmann equation without extra degrees of freedom. It is shown that, at least for isotropic models in LQC, this issue is naturally resolved and a covariant effective action can be found if one considers higher order theories of gravity but faithfully follows effective field theory techniques. However, our analysis also raises doubts on whether a covariant description without background structures can be found for anisotropic models.
Device for balancing parallel strings
Mashikian, Matthew S.
1985-01-01
A battery plant is described which features magnetic circuit means in association with each of the battery strings in the battery plant for balancing the electrical current flow through the battery strings by equalizing the voltage across each of the battery strings. Each of the magnetic circuit means generally comprises means for sensing the electrical current flow through one of the battery strings, and a saturable reactor having a main winding connected electrically in series with the battery string, a bias winding connected to a source of alternating current and a control winding connected to a variable source of direct current controlled by the sensing means. Each of the battery strings is formed by a plurality of batteries connected electrically in series, and these battery strings are connected electrically in parallel across common bus conductors.
Infrared divergences and harmonic anomalies in the two-loop superstring effective action
Pioline, Boris
2015-01-01
We analyze the pertubative contributions to the $D^4 R^4$ and $D^6 R^4$ couplings in the low-energy effective action of type II string theory compactified on a torus $T^d$, with particular emphasis on two-loop corrections. In general, it is necessary to introduce an infrared cut-off $\\Lambda$ to separate local interactions from non-local effects due to the exchange of massless states. We identify the degenerations of the genus-two Riemann surface which are responsible for power-like dependence on $\\Lambda$, and give an explicit prescription for extracting the $\\Lambda$-independent effective couplings. These renormalized couplings are then shown to be eigenmodes of the Laplace operator with respect to the torus moduli, up to computable anomalous source terms arising in the presence of logarithmic divergences, in precise agreement with predictions from U-duality. Our results for the two-loop $D^6 R^4$ contribution also probe essential properties of the Kawazumi-Zhang invariant
Infrared divergences and harmonic anomalies in the two-loop superstring effective action
Energy Technology Data Exchange (ETDEWEB)
Pioline, Boris [CERN PH-TH,Case C01600, CERN, CH-1211 Geneva 23 (Switzerland); Sorbonne Universités,UPMC Université Paris 6, UMR 7589, F-75005 Paris (France); Laboratoire de Physique Théorique et Hautes Energies, CNRS UMR 7589,Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris cedex 05 (France); Russo, Rodolfo [Centre for Research in String Theory, School of Physics and Astronomy,Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom)
2015-12-16
We analyze the pertubative contributions to the D{sup 4}R{sup 4} and D{sup 6}R{sup 4} couplings in the low-energy effective action of type II string theory compactified on a torus T{sup d}, with particular emphasis on two-loop corrections. In general, it is necessary to introduce an infrared cut-off Λ to separate local interactions from non-local effects due to the exchange of massless states. We identify the degenerations of the genus-two Riemann surface which are responsible for power-like dependence on Λ, and give an explicit prescription for extracting the Λ-independent effective couplings. These renormalized couplings are then shown to be eigenmodes of the Laplace operator with respect to the torus moduli, up to computable anomalous source terms arising in the presence of logarithmic divergences, in precise agreement with predictions from U-duality. Our results for the two-loop D{sup 6}R{sup 4} contribution also probe essential properties of the Kawazumi-Zhang invariant.
International Nuclear Information System (INIS)
Zanzi, Andrea
2010-01-01
The chameleonic behavior of the string theory dilaton is suggested. Some of the possible consequences of the chameleonic string dilaton are analyzed in detail. In particular, (1) we suggest a new stringy solution to the cosmological constant problem and (2) we point out the nonequivalence of different conformal frames at the quantum level. In order to obtain these results, we start taking into account the (strong coupling) string loop expansion in the string frame (S-frame), therefore the so-called form factors are present in the effective action. The correct dark energy scale is recovered in the Einstein frame (E-frame) without unnatural fine-tunings and this result is robust against all quantum corrections, granted that we assume a proper structure of the S-frame form factors in the strong coupling regime. At this stage, the possibility still exists that a certain amount of fine-tuning may be required to satisfy some phenomenological constraints. Moreover in the E-frame, in our proposal, all the interactions are switched off on cosmological length scales (i.e., the theory is IR-free), while higher derivative gravitational terms might be present locally (on short distances) and it remains to be seen whether these facts clash with phenomenology. A detailed phenomenological analysis is definitely necessary to clarify these points.
String dynamics, spontaneous breaking of supersymmetry, and dual scalar field theory
International Nuclear Information System (INIS)
Liu Luxin
2009-01-01
The dynamics of a vortex string, which describes the Nambu-Goldstone modes of the spontaneous breakdown of the target space D=4, N=1 supersymmetry and internal U(1) R symmetry to the world sheet ISO(1,1) symmetry, is constructed by using the approach of nonlinear realization. The resulting action describing the low energy oscillations of the string into the covolume (super)space is found to have an invariant synthesis form of the Akulov-Volkov and Nambu-Goto actions. Its dual scalar field action is obtained by means of introducing two vectorial Lagrangian multipliers into the action of the string.
Scattering of long folded strings and mixed correlators in the two-matrix model
International Nuclear Information System (INIS)
Bourgine, J.-E.; Hosomichi, K.; Kostov, I.; Matsuo, Y.
2008-01-01
We study the interactions of Maldacena's long folded strings in two-dimensional string theory. We find the amplitude for a state containing two long folded strings to come and go back to infinity. We calculate this amplitude both in the worldsheet theory and in the dual matrix model, the matrix quantum mechanics. The matrix model description allows to evaluate the amplitudes involving any number of long strings, which are given by the mixed trace correlators in an effective two-matrix model
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.)
Energy Technology Data Exchange (ETDEWEB)
Riordan, M. [Stanford University and the University of California, Santa Cruz (United States)]. E-mail: mriordan@ucsc.edu
2007-02-15
In the last few decades, however, physical theory has drifted away from the professional norms advocated by Newton and other enlightenment philosophers. A vast outpouring of hypotheses has occurred under the umbrella of what is widely called string theory. But string theory is not really a 'theory' at all - at least not in the strict sense that scientists generally use the term. It is instead a dense, weedy thicket of hypotheses and conjectures badly in need of pruning. That pruning, however, can come only from observation and experiment, to which string theory (a phrase I will grudgingly continue using) is largely inaccessible. String theory was invented in the 1970s in the wake of the Standard Model of particle physics. Encouraged by the success of gauge theories of the strong, weak and electromagnetic forces, theorists tried to extend similar ideas to energy and distance scales that are orders of magnitude beyond what can be readily observed or measured. The normal, healthy intercourse between theory and experiment - which had led to the Standard Model - has broken down, and fundamental physics now finds itself in a state of crisis. So it is refreshing to hear from a theorist - one who was deeply involved with string theory and championed it in his previous book, Three Roads to Quantum Gravity - that all is not well in this closeted realm. Smolin argues from the outset that viable hypotheses must lead to observable consequences by which they can be tested and judged. String theory by its very nature does not allow for such probing, according to Smolin, and therefore it must be considered as an unprovable conjecture. Towards the end of his book, Smolin suggests other directions fundamental physics can take, particularly in the realm of quantum gravity, to resolve its crisis and reconnect with the observable world. From my perspective, he leans a bit too heavily towards highly speculative ideas such as doubly special relativity, modified Newtonian
Fluctuations from cosmic strings and the microwave background
International Nuclear Information System (INIS)
Brandenberger, R.H.; Turok, N.
1986-01-01
The spectrum of energy-density perturbations and anisotropies in the microwave background radiation are calculated in models with cosmic strings. The computations are based on a mathematical model of the network of cosmic strings as a combination of a random walk of infinite strings and a distribution of string loops. The energy-density distribution is scale invariant at Hubble radius crossing, but the k dependence of the spectrum is nontrivial and not equal to the result for adiabatic linear perturbations. The anisotropies in the microwave background radiation are smaller than the observational upper bounds on all angular scales for a value μGapprox.2 x 10 -6 obtained from independent astrophysical considerations. We include both the effects due to gravitational lensing from long strings and from local gravitational perturbations due to loops (the Sachs-Wolfe effect)
Integrable equation of state for noisy cosmic string
International Nuclear Information System (INIS)
Carter, B.
1990-01-01
It is argued that, independently of the detailed (thermal or more general) noise spectrum of the microscopic extrinsic excitations that can be expected on an ordinary cosmic string, their effect can be taken into account at a macroscopic level by replacing the standard isotropic Goto-Nambu-type string model by the nondegenerate string model characterized by an equation of state of the nondispersive ''fixed determinant'' type, with the effective surface stress-energy tensor satisfying (T ν ν ) 2 -T μ ν T ν μ =2T 0 2 , where T 0 is a constant representing the null-state limit of the string tension T, whose product with the energy density U of the string is thereby held fixed: TU=T 0 2 . It is shown that this equation of state has the special property of giving rise (in a flat background) to explicitly integrable dynamical equations
Calculability and stability in the flipped string
Energy Technology Data Exchange (ETDEWEB)
Lopez, J.L.; Nanopoulos, D.V. (Texas A and M Univ., College Station, TX (USA). Center for Theoretical Physics Houston Advanced Research Center (HARC), The Woodlands, TX (USA). Astroparticle Physics Group)
1991-03-07
We show that the highly successful structure of the recently proposed superstring flipped SU(5) model remains intact after the inclusion in the superpotential of the low-energy effective theory of all relevant string-induced nonrenormalizable terms. This structure provides for only two light Higgs doublets, hierarchical fermion mass matrices, and an adequate proton lifetime. We reach this conclusion explicit calculations using a recently derived set of rules to evaluate nonrenormalizable terms in the four-dimensional free fermionic formulation of superstrings. This remarkable stability of the infrared limit of the flipped string makes its experimental predictions trustworthy and hence its physical existence falsifiable. (orig.).
Techniques for calculations with nPI effective actions
Directory of Open Access Journals (Sweden)
Carrington M.E.
2015-01-01
Full Text Available We consider a symmetric scalar theory with quartic coupling in 2- and 3- dimensions and compare the self-consistent 4-point vertex obtained from the 4PI effective action with the Bethe-Salpeter 4-vertex from 2PI effective action. We show that when the coupling is large the contributions from the higher order effective action are large. We also show that one can solve the 2PI equations of motion in 4-dimensions, without introducing counter-terms, using a renormalization group method. This method provides a promising starting point to study the renormalization of higher order nPI theories.
Cosmic strings in f(R,L{sub m}) gravity
Energy Technology Data Exchange (ETDEWEB)
Harko, Tiberiu [University College London, Department of Mathematics, London (United Kingdom); Lake, Matthew J. [Naresuan University, The Institute for Fundamental Study, ' ' The Tah Poe Academia Institute' ' , Phitsanulok (Thailand); Ministry of Education, Thailand Center of Excellence in Physics, Bangkok (Thailand)
2015-02-01
We consider Kasner-type static, cylindrically symmetric interior string solutions in the f(R,L{sub m}) theory of modified gravity. The physical properties of the string are described by an anisotropic energy-momentum tensor satisfying the condition T{sub t}{sup t} = T{sub z}{sup z}; that is, the energy density of the string along the z-axis is equal to minus the string tension. As a first step in our study we obtain the gravitational field equations in the f(R,L{sub m}) theory for a general static, cylindrically symmetric metric, and then for a Kasner-type metric, in which the metric tensor components have a power law dependence on the radial coordinate r. String solutions in two particular modified gravity models are investigated in detail. The first is the so-called ''exponential'' modified gravity, in which the gravitational action is proportional to the exponential of the sum of the Ricci scalar and matter Lagrangian, and the second is the ''self-consistent model'', obtained by explicitly determining the gravitational action from the field equations under the assumption of a power law dependent matter Lagrangian. In each case, the thermodynamic parameters of the string, as well as the precise form of the matter Lagrangian, are explicitly obtained. (orig.)
On the influence of reward on action-effect binding
Directory of Open Access Journals (Sweden)
Paul Simon Muhle-Karbe
2012-11-01
Full Text Available Ideomotor theory states that the formation of anticipatory representations about the perceptual consequences of an action (i.e. action-effect (A-E binding provides the functional basis of voluntary action control. A host of studies has demonstrated that A-E binding occurs fast and effortlessly, yet only little is known about cognitive and affective factors that influence this learning process. In the present study, we sought to test whether the motivational value of an action modulates the acquisition of A-E associations. To this end, we associated specific actions with monetary incentives during the acquisition of novel A-E mappings. In a subsequent test phase, the degree of binding was assessed by presenting the former effect stimuli as task-irrelevant response primes in a forced-choice response task in the absence of any reward. Binding, as indexed by response priming through the former action effects, was only found for reward-related A-E mappings. Moreover, the degree to which reward associations modulated the binding strength was predicted by individuals’ trait sensitivity to reward. These observations indicate that the association of actions and their immediate outcomes depends on the motivational value of the action during learning, as well as on the motivational disposition of the individual. On a larger scale, these findings also highlight the link between ideomotor theories and reinforcement-learning theories, providing an interesting perspective for future research on anticipatory regulation of behavior.
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)
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.
International Nuclear Information System (INIS)
Gross, D.J.
1985-01-01
String theories offer a way of realizing the potential of supersymmetry, Kaluza-Klein and much more. They represent a radical departure from ordinary quantum field theory, but in the direction of increased symmetry and structure. They are based on an enormous increase in the number of degrees of freedom, since in addition to fermionic coordinates and extra dimensions, the basic entities are extended one dimensional objects instead of points. Correspondingly the symmetry group is greatly enlarged, in a way that we are only beginning to comprehend. At the very least this extended symmetry contains the largest group of symmetries that can be contemplated within the framework of point field theories-those of ten-dimensional supergravity and super Yang-Mills theory. Types of string theories and the phenomenology to be expected from them are reviewed
Regge behavior saves string theory from causality violations
DEFF Research Database (Denmark)
di Vecchia, Paolo; Giuseppe, D'Appollonio; Russo, Rodolfo
2015-01-01
Higher-derivative corrections to the Einstein-Hilbert action are present in bosonic string theory leading to the potential causality violations recently pointed out by Camanho et al. [1]. We analyze in detail this question by considering high-energy string-brane collisions at impact parameters b....... Such violations are instead neatly avoided when the full structure of string theory — and in particular its Regge behavior — is taken into account....... ≤ l s (the string-length parameter) with l s ≫ R p (the characteristic scale of the Dp-brane geometry). If we keep only the contribution of the massless states causality is violated for a set of initial states whose polarization is suitably chosen with respect to the impact parameter vector...
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
International Nuclear Information System (INIS)
Volovich, I.V.
1987-01-01
The hypothesis of the possible p-adic structure of spacetime is considered. The p-adic Veneziano amplitude is proposed and the main properties of the p-adic string theory are discussed. The analogous questions on the Galois field are also discussed. In this case the Jacobi sum plays the role of the Veneziano amplitude which can be expressed by means of the I-adic cohomology of the Fermat curves. The corresponding vertex operator is given. (author)
Exactly soluble dynamics of (p,q) string near macroscopic fundamental strings
International Nuclear Information System (INIS)
Bak, Dongsu; Rey, Soojong; Yee, Houng
2004-01-01
We study dynamics of type-IIB bound-state of a Dirichlet string and n fundamental strings in the background of N fundamental strings. Because of supergravity potential, the bound-state string is pulled to the background fundamental strings, whose motion is described by open string rolling radion field. The string coupling can be made controllably weak and, in the limit 1 2 st n 2 st N, the bound-state energy involved is small compared to the string scale. We thus propose rolling dynamics of open string radion in this system as an exactly solvable analog for rolling dynamics of open string tachyon in decaying D-brane. The dynamics bears a novel feature that the worldsheet electric field increases monotonically to the critical value as the bound-state string falls into the background string. Close to the background string, D string constituent inside the bound-state string decouples from fundamental string constituents. (author)
The theta-structure in string theories - 1: bosonic strings
International Nuclear Information System (INIS)
Li Miao.
1985-09-01
We explored the theta-structures in bosonic string theories which are similar to those in gauge field theories. The theta-structure of string is due to the multiply connected spatial compact subspace of space-time. The work of this paper shows that there is an energy band E(theta) in the string theory and one may move the tachyon out in theory by choosing some proper theta parameters. (author)
The internal anticipation of sensory action effects: when action induces FFA and PPA activity
Directory of Open Access Journals (Sweden)
Simone Kühn
2010-06-01
Full Text Available Voluntary action – in particular the ability to produce desired effects in the environment – is fundamental to human existence. According to ideomotor theory we can achieve goals in the environment by means of anticipating their outcomes. We aimed at providing neurophysiological evidence for the assumption that performing actions calls for the activation of brain areas associated with the sensory effects usually evoked by the actions. We conducted an fMRI study in which right and left button presses lead to the presentation of face and house pictures. We compared a baseline phase with the same phase after participants experienced the association between button presses and pictures. We found an increase in the parahippocampal place area (PPA for the response that has been associated with house pictures and fusiform face area (FFA for the response that has been coupled with face pictures. This observation constitutes support for ideomotor theory.
An invariant string propagator
International Nuclear Information System (INIS)
Cohen, A.; Moore, G.; Nelson, P.; Polchinski, J.
1986-01-01
The authors show that the Polyakov path integral is used to define off-shell quantities in string theory. The path integral of Polyakov gives an elegant description of strings and their interactions. However, its use has been limited to obtaining the Koba-Nielsen expressions for S-matrix elements. It is not yet clear what quantities make sense in string theory. This study shows that the path integral can be used to define off-shell quantities as well. In particular it defines a natural n-point function in loop space as the sum of all world surfaces bounded by n specific spacetime curves. The reader is referred for more detail. The report first outlines general evaluation then discusses the additional features added by boundaries. Locally, the three gauge freedoms ξ/sup a/ and δphi can be used to take g/sub ab/ (σ) to the unit matrix. Globally, this is not quite possible. In general the researchers choose a family of fiducial metrics g/sub ab/ (σ,tau), depending on a finite number of Teichmuller parameters tau, and every metric is gauge equivalent to one of these
International Nuclear Information System (INIS)
Aldazabal, G.; Ibanez, L.E.; Uranga, A.M.
1996-01-01
We study in detail the structure of Grand Unified Theories derived as the low-energy limit of orbifold four-dimensional strings. To this aim, new techniques for building level-two symmetric orbifold theories are presented. New classes of GUTs in the context of symmetric orbifolds are then constructed. The method of permutation modding is further explored and SO(10) GUTs with both 45- or 54-plets are obtained. SU(5) models are also found through this method. It is shown that, in the context of symmetric orbifold SO(10) GUTs, only a single GUT Higgs, either a 54 or a 45, can be present and it always resides in an order-two untwisted sector. Very restrictive results also hold in the case of SU(5). General properties and selection rules for string GUTs are described. Some of these selection rules forbid the presence of some particular GUT-Higgs couplings which are sometimes used in SUSY-GUT model building. Some semi-realistic string GUT examples are presented and their properties briefly discussed. (orig.)
Fingerprints in Compressed Strings
DEFF Research Database (Denmark)
Bille, Philip; Cording, Patrick Hagge; Gørtz, Inge Li
2013-01-01
The Karp-Rabin fingerprint of a string is a type of hash value that due to its strong properties has been used in many string algorithms. In this paper we show how to construct a data structure for a string S of size N compressed by a context-free grammar of size n that answers fingerprint queries...... derivative that captures LZ78 compression and its variations) we get O(loglogN) query time. Hence, our data structures has the same time and space complexity as for random access in SLPs. We utilize the fingerprint data structures to solve the longest common extension problem in query time O(logNlogℓ) and O....... That is, given indices i and j, the answer to a query is the fingerprint of the substring S[i,j]. We present the first O(n) space data structures that answer fingerprint queries without decompressing any characters. For Straight Line Programs (SLP) we get O(logN) query time, and for Linear SLPs (an SLP...
17 CFR 9.12 - Effective date of disciplinary or access denial action.
2010-04-01
... ACTIONS Notice and Effective Date of Disciplinary Action or Access Denial Action § 9.12 Effective date of disciplinary or access denial action. (a) Effective date. Any disciplinary or access denial action taken by an... cause a disciplinary action to become effective prior to that time if: (1) As authorized by § 8.25 of...
Consistent boundary conditions for open strings
International Nuclear Information System (INIS)
Lindstroem, Ulf; Rocek, Martin; Nieuwenhuizen, Peter van
2003-01-01
We study boundary conditions for the bosonic, spinning (NSR) and Green-Schwarz open string, as well as for (1+1)-dimensional supergravity. We consider boundary conditions that arise from (1) extremizing the action, (2) BRST, rigid or local supersymmetry, or κ(Siegel)-symmetry of the action, (3) closure of the set of boundary conditions under the symmetry transformations, and (4) the boundary limits of bulk Euler-Lagrange equations that are 'conjugate' to other boundary conditions. We find corrections to Neumann boundary conditions in the presence of a bulk tachyon field. We discuss a boundary superspace formalism. We also find that path integral quantization of the open string requires an infinite tower of boundary conditions that can be interpreted as a smoothness condition on the doubled interval; we interpret this to mean that for a path-integral formulation of open strings with only Neuman boundary conditions, the description in terms of orientifolds is not just natural, but is actually fundamental
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)
How to simulate global cosmic strings with large string tension
Energy Technology Data Exchange (ETDEWEB)
Klaer, Vincent B.; Moore, Guy D., E-mail: vklaer@theorie.ikp.physik.tu-darmstadt.de, E-mail: guy.moore@physik.tu-darmstadt.de [Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstraße 2, Darmstadt, D-64289 Germany (Germany)
2017-10-01
Global string networks may be relevant in axion production in the early Universe, as well as other cosmological scenarios. Such networks contain a large hierarchy of scales between the string core scale and the Hubble scale, ln( f {sub a} / H ) ∼ 70, which influences the network dynamics by giving the strings large tensions T ≅ π f {sub a} {sup 2} ln( f {sub a} / H ). We present a new numerical approach to simulate such global string networks, capturing the tension without an exponentially large lattice.
Large-D gravity and low-D strings.
Emparan, Roberto; Grumiller, Daniel; Tanabe, Kentaro
2013-06-21
We show that in the limit of a large number of dimensions a wide class of nonextremal neutral black holes has a universal near-horizon limit. The limiting geometry is the two-dimensional black hole of string theory with a two-dimensional target space. Its conformal symmetry explains the properties of massless scalars found recently in the large-D limit. For black branes with string charges, the near-horizon geometry is that of the three-dimensional black strings of Horne and Horowitz. The analogies between the α' expansion in string theory and the large-D expansion in gravity suggest a possible effective string description of the large-D limit of black holes. We comment on applications to several subjects, in particular to the problem of critical collapse.
String-mediated electroweak baryogenesis a critical analysis
Cline, J M; Moore, G D; Riotto, Antonio; Cline, Jim; Espinosa, Jose; Moore, Guy D.; Riotto, Antonio
1999-01-01
We study the scenario of electroweak baryogenesis mediated by nonsuperconducting cosmic strings. This idea relies upon electroweak symmetry being restored in a region around the core of the topological defect so that, within this region, the rate of baryon number violation is enhanced. We compute numerically how effectively baryon number is violated along a cosmic string, at an epoch when the baryon number violation rate elsewhere is negligible. We show that B-violation along nonsuperconducting strings is quite inefficient. When proper accounting is taken of the velocity dependence of the baryon number production by strings, it proves too small to explain the observed abundance by at least ten orders of magnitude, whether the strings are in the friction dominated or the scaling regime.
Radiative processes of two entangled atoms in cosmic string spacetime
Cai, Huabing; Ren, Zhongzhou
2018-01-01
We investigate the radiative processes of two static two-level atoms in a maximally entangled state coupled to vacuum electromagnetic field in the cosmic string spacetime. We find that the decay rate from the entangled state to the ground state crucially depends on the atomic separation, the polarization directions of the individual atoms, the atom-string distance and the deficit angle induced by the string. As the atom-string distance increases, the decay rate oscillates around the result in Minkowski spacetime and the amplitude gradually decreases. The oscillation is more severe for larger planar angle deficit. We analyze the decay rate in different circumstances such as near zone and specific polarization cases. Some comparisons between symmetric and antisymmetric states are performed. By contrast with the case in Minkowski spacetime, we can reveal the effects of the cosmic string on the radiative properties of the entangled atoms.
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
Aspects of non-geometry in string theory
International Nuclear Information System (INIS)
Patalong, Peter
2013-01-01
This thesis investigates various manifestations of non-geometry in string theory. It utilises different frameworks to study how non-geometry appears in the target space, how non-geometry and non-geometric fluxes are interconnected, how non-geometry can be captured in effective field theories and how a possible extension of the standard string worldsheet model can accommodate non-geometric setups. The first part provides an example that non-geometry can imply non-commutativity of the closed string coordinate fields. Three T-dual frames are investigated, the three-torus with constant H-flux, the twisted torus and the torus with non-geometric flux Q. Under the assumption of dilute flux, a mode expansion and the canonical quantisation are carried out in the second case up to linear order in the flux parameter. T-duality is then used to relate the commutators of the string expansion modes to the coordinate field commutator in the non-geometric third frame. Non-commutativity is found and related to the non-geometric flux Q and the string winding, it therefore appears as an intrinsically string theoretic feature. The second part investigates non-geometry in the context of ten-dimensional effective field theories, i.e. double field theory and supergravity. A field redefinition is implemented that takes the form of a T-duality transformation, it reveals an alternative set of field variables allowing to define non-geometric fluxes Q and R in higher dimensions. The perspective of double field theory provides a geometric interpretation of those by taking into account a new type of covariant winding derivative. The perspective of the ten-dimensional supergravity allows to investigate the interplay between non-geometric field configurations and non-geometric fluxes. For the three-torus example, a well-defined action can be found, and a simple dimensional reduction makes contact to the known four-dimensional potential. It thus proves the correct uplift of Q and R to higher
Effective action in multidimensional quantum gravity and spontaneous compactification
International Nuclear Information System (INIS)
Bagrov, V.G.; Bukhbinder, I.L.; Odintsov, S.D.
1987-01-01
One-loop effective action (the Casimir energy) is obtained for a special model of multidimensional quantum gravity and several variants of the d-dimensional quantum R 2 gravity in the space M 4 xT d-4 , where M 4 is the Minkowski space and T d-4 is the (d-4)-dimensional torus. It is shown that the effective action for the conformal gravity and the R 2 gravity without cosmological and Einstein's terms lead to an instability of the classical compactification. A numerical calculation reveals that the effective action for the five-dimensional R 2 gravity with the cosmological term is compatible with a self-consistent spontaneous compactification. The one-loop effective action is also obtained for the five dimensional Einstein gravity with the antisymmetrical torsion in the space M 4 xS 1 , where S 1 is the one-dimensional sphere
Effective action in multidimensional quantum gravity, and spontaneous compactification
International Nuclear Information System (INIS)
Bagrov, V.G.; Bukhbinder, I.L.; Odintsov, S.D.
1987-01-01
The one-loop effective action (Casimir energy) is obtained for a special form of model of multidimensional quantum gravity and for several variants of d-dimensional quantum R 2 -gravity on the space M 4 x T/sub d//sub -4/, where M 4 is Minkowski space and T/sub d//sub -4/ is the (d-4)-dimensional torus. It is shown that the effective action of the model of multidimensional quantum gravity and R 2 -gravity without the cosmological term and Einstein term leads to instability of the classical compactification. By a numerical calculation it is demonstrated that the effective action of five-dimensional R 2 -gravity with the cosmological term admits a self-consistent spontaneous compactification. The one-loop effective action is also found for five-dimensional Einstein gravity with antisymmetric torsion on the space M 4 x S 1 (S 1 is the one-dimensional sphere)
Effective average action for gauge theories and exact evolution equations
International Nuclear Information System (INIS)
Reuter, M.; Wetterich, C.
1993-11-01
We propose a new nonperturbative evolution equation for Yang-Mills theories. It describes the scale dependence of an effective action. The running of the nonabelian gauge coupling in arbitrary dimension is computed. (orig.)
Maximal unbordered factors of random strings
DEFF Research Database (Denmark)
Cording, Patrick Hagge; Knudsen, Mathias Bæk Tejs
2016-01-01
A border of a string is a non-empty prefix of the string that is also a suffix of the string, and a string is unbordered if it has no border. Loptev, Kucherov, and Starikovskaya [CPM 2015] conjectured the following: If we pick a string of length n from a fixed alphabet uniformly at random...
Aspects of type $0$ string theory
Blumenhagen, R; Kumar, A; Lüst, Dieter
2000-01-01
A construction of compact tachyon-free orientifolds of the non-supersymmetric Type 0B string theory is presented. Moreover, we study effective non-supersymmetric gauge theories arising on self-dual D3-branes in Type 0B orbifolds and orientifolds.
Instantons and cosmologies in string theory
Collinucci, Giulio
2005-01-01
This thesis deals with problems in two subdomains of string theory that are a priori unrelated, and in the last chapter, links are established between those two. The first topic of research is that of D-instantons. These are mathematical objects that allow one to compute physical effects that are
Quantum properties of QCD string fragmentation
Directory of Open Access Journals (Sweden)
Todorova-Nová Šárka
2016-01-01
Full Text Available A simple quantization concept for a 3-dim QCD string is used to derive properties of QCD flux tube from the mass spectrum of light mesons and to predict observable quantum effects in correlations between adjacent hadrons. The quantized fragmentation model is presented and compared with experimental observations.
Strings, vortex rings, and modes of instability
Directory of Open Access Journals (Sweden)
Steven S. Gubser
2015-03-01
Full Text Available We treat string propagation and interaction in the presence of a background Neveu–Schwarz three-form field strength, suitable for describing vortex rings in a superfluid or low-viscosity normal fluid. A circular vortex ring exhibits instabilities which have been recognized for many years, but whose precise boundaries we determine for the first time analytically in the small core limit. Two circular vortices colliding head-on exhibit stronger instabilities which cause splitting into many small vortices at late times. We provide an approximate analytic treatment of these instabilities and show that the most unstable wavelength is parametrically larger than a dynamically generated length scale which in many hydrodynamic systems is close to the cutoff. We also summarize how the string construction we discuss can be derived from the Gross–Pitaevskii Lagrangian, and also how it compares to the action for giant gravitons.
On D-brane anti D-brane effective actions and their corrections to all orders in alpha-prime
International Nuclear Information System (INIS)
Hatefi, Ehsan
2013-01-01
Based on a four point function, the S-matrix elements at disk level of the scattering amplitude of one closed string Ramond-Ramond field (C) and two tachyons and one scalar field, we find out new couplings in brane anti brane effective actions for p = n, p+2 = n cases. Using the infinite corrections of the vertex of one RR, one gauge and one scalar field and applying the correct expansion, it is investigated in detail how we produce the infinite gauge poles of the amplitude for p = n case. By discovering new higher derivative corrections of two tachyon-two scalar couplings in brane anti brane systems to all orders in α', we also obtain the infinite scalar poles in (t'+s'+u)-channel in field theory. Working with the complete form of the amplitude with the closed form of the expansion and comparing all the infinite contact terms of this amplitude, we derive several new Wess-Zumino couplings with all their infinite higher derivative corrections in the world volume of brane anti brane systems. In particular, in producing all the infinite scalar poles of C V φ V T V T > , one has to consider the fact that scalar's vertex operator in (-1)-picture must carry the internal σ 3 Chan-Paton matrix. The symmetric trace effective action has a non-zero coupling between Dφ (1)i and Dφ (2) i while this coupling does not exist in ordinary trace effective action
Fast Searching in Packed Strings
DEFF Research Database (Denmark)
Bille, Philip
2009-01-01
Given strings P and Q the (exact) string matching problem is to find all positions of substrings in Q matching P. The classical Knuth-Morris-Pratt algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear time which is optimal if we can only read one character at the time....... However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed representation. Let m...... word-RAM with logarithmic word size we present an algorithm using time O(n/log(sigma) n + m + occ) Here occ is the number of occurrences of P in Q. For m = o(n) this improves the O(n) bound...
Eisenstein series and string thresholds
International Nuclear Information System (INIS)
Obers, N.A.; Pioline, B.
2000-01-01
We investigate the relevance of Eisenstein series for representing certain G(Z)-invariant string theory amplitudes which receive corrections from BPS states only. G(Z) may stand for any of the mapping class, T-duality and U-duality groups Sl(d,Z), SO(d,d,Z) or E d+1(d+1) (Z) respectively. Using G(Z)-invariant mass formulae, we construct invariant modular functions on the symmetric space K backslash G(R) of non-compact type, with K the maximal compact subgroup of G(R), that generalize the standard non-holomorphic Eisenstein series arising in harmonic analysis on the fundamental domain of the Poincare upper half-plane. Comparing the asymptotics and eigenvalues of the Eisenstein series under second order differential operators with quantities arising in one- and g-loop string amplitudes, we obtain a manifestly T-duality invariant representation of the latter, conjecture their non-perturbative U-duality invariant extension, and analyze the resulting non-perturbative effects. This includes the R 4 and R 4 H -4 g -4 couplings in toroidal compactifications of M-theory to any dimension D≥4 and D≥6 respectively. (orig.)
Urban Heat Island Effect Actions - Neighborhood Data
Louisville Metro Government — The urban heat island effect — defined as the difference in temperature between the core of Louisville and its suburbs — contributes to heat-related illnesses and...
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
Experimenting with string musical instruments
LoPresto, Michael C.
2012-03-01
What follows are several investigations involving string musical instruments developed for and used in a Science of Sound & Light course. The experiments make use of a guitar, orchestral string instruments and data collection and graphing software. They are designed to provide students with concrete examples of how mathematical formulae, when used in physics, represent reality that can actually be observed, in this case, the operation of string musical instruments.
Radiosensitizers action on Iodine 131 therapeutical effect
International Nuclear Information System (INIS)
Agote, Marcos; Kreimann, Erica L.; Bocanera, Laura V.; Dagrosa, Maria A.; Juvenal, Guillermo J.; Pisarev, Mario A.
1999-01-01
Present studies were aimed to research the possible application of a radiosensitizer, nicotinamide, to increase the therapeutical effect of radioiodine. There were used goitrous and normal rats with growing dose of Iodine 131, with and without simultaneous treatment with nicotinamide. The obtained results show that the nicotinamide treatment importantly increases the thyroid radio destructive effect induced by radioiodine. Under these experimental conditions, nicotinamide induces to a significant increase of thyroid vascularisation, without changes in the proteins ADP-ribosylation activity. These results show, for the first time, the radiosensitizer effect of nicotinamide in front of Iodine 131 and give the possibility of using it in the treatment of hyperthyroid or thyroid difference cancer patients. (author)
String breaking with Wilson loops?
Kratochvila, S; Kratochvila, Slavo; Forcrand, Philippe de
2003-01-01
A convincing, uncontroversial observation of string breaking, when the static potential is extracted from Wilson loops only, is still missing. This failure can be understood if the overlap of the Wilson loop with the broken string is exponentially small. In that case, the broken string ground state will only be seen if the Wilson loop is long enough. Our preliminary results show string breaking in the context of the 3d SU(2) adjoint static potential, using the L\\"uscher-Weisz exponential variance reduction approach. As a by-product, we measure the fundamental SU(2) static potential with improved accuracy and see clear deviations from Casimir scaling.
Schomerus, Volker
2017-01-01
Since its conception in the 1960s, string theory has been hailed as one of the most promising routes we have to unify quantum mechanics and general relativity. This book provides a concise introduction to string theory explaining central concepts, mathematical tools and covering recent developments in physics including compactifications and gauge/string dualities. With string theory being a multidisciplinary field interfacing with high energy physics, mathematics and quantum field theory, this book is ideal for both students with no previous knowledge of the field and scholars from other disciplines who are looking for an introduction to basic concepts.
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.)
Lin, Chien-Hung
2017-05-01
We generalize the string-net construction to multiple flavors of strings, each of which is labeled by the elements of an Abelian group Gi. The same flavor of strings can branch, while different flavors of strings can cross one another and thus they form intersecting string nets. We systematically construct the exactly soluble lattice Hamiltonians and the ground-state wave functions for the intersecting string-net condensed phases. We analyze the braiding statistics of the low-energy quasiparticle excitations and find that our model can realize all the topological phases as the string-net model with group G =∏iGi . In this respect, our construction provides various ways of building lattice models which realize topological order G , corresponding to different partitions of G and thus different flavors of string nets. In fact, our construction concretely demonstrates the Künneth formula by constructing various lattice models with the same topological order. As an example, we construct the G =Z2×Z2×Z2 string-net model which realizes a non-Abelian topological phase by properly intersecting three copies of toric codes.
Haouzi, Nathan; Kozçaz, Can
2017-01-01
Starting from type IIB string theory on an $ADE$ singularity, the (2,0) little string arises when one takes the string coupling $g_s$ to 0. In this setup, we give a unified description of the codimension-two defects of the little string, for any simple Lie algebra ${\\mathfrak{g}}$. Geometrically, these are D5 branes wrapping 2-cycles of the singularity. Equivalently, the defects are specified by a certain set of weights of $^L {\\mathfrak{g}}$, the Langlands dual of ${\\mathfrak{g}}$. As a firs...
Kiritsis, Elias
2007-01-01
This book is the essential new introduction to modern string theory, by one of the world's authorities on the subject. Concise, clearly presented, and up-to-date, String Theory in a Nutshell brings together the best understood and most important aspects of a theory that has been evolving since the early 1980s. A core model of physics that substitutes one-dimensional extended ""strings"" for zero-dimensional point-like particles (as in quantum field theory), string theory has been the leading candidate for a theory that would successfully unify all fundamental forces of nature, includin
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.)
Effect of mutagen combined action on Chlamydomonas reinhardtii cells. II
International Nuclear Information System (INIS)
Podstavkova, S.; Vlcek, D.; Dubovsky, J.
1978-01-01
The effect of UV radiation and UV radiation combined with alkylnitrosourea derivatives (N-methyl-N-nitrosourea and N-ethyl-N-nitrosourea) was observed on survival of cells of the algae Chlamydomonas reinhardtii. In particular, single parts were evaluated of the overall lethal effect - dying of cells before division and dying of cells after division. It was found that the combined action of low doses of UV radiation and alkylnitrosoureas result in a pronounced protective effect which manifests itself by a higher frequency of surviving cells than was that effected by the action of alkylnitrosoureas alone. As a result of combined action with higher doses of UV radiation this effect is lost, and the resultant values will come close to the theoretically anticipated values. This gradual transition from a protective to an additive effect mainly manifests itself by changes in the proportion of cells dying before division. (author)
Large spin limit of AdS5xS5 string theory and low energy expansion of ferromagnetic spin chains
International Nuclear Information System (INIS)
Kruczenski, M.; Ryzhov, A.V.; Tseytlin, A.A.
2004-01-01
By considering AdS 5 xS 5 string states with large S 5 angular momenta one can provide non-trivial quantitative checks of the AdS/CFT duality. A string rotating in S 5 with two angular momenta J 1 , J 2 is dual to an operator in N=4 SYM theory whose conformal dimension can be computed by diagonalizing a (generalization of) spin 1/2 Heisenberg chain Hamiltonian. It was recently argued and verified to lowest order in a large J=J 1 +J 2 expansion, that the Heisenberg chain can be described using a non-relativistic low energy effective 2d action for a unit vector field n i which exactly matches the corresponding large J limit of the classical AdS 5 xS 5 string action. In this paper we show that this agreement extends to the next order and develop a systematic procedure for computing higher orders in such large angular momentum expansion. This involves several non-trivial steps. On the string side, we need to choose a special gauge with a non-diagonal world-sheet metric which insures that the angular momentum is uniformly distributed along the string, as indeed is the case on the spin chain side. We need also to implement an order by order redefinition of the field n i to get an action linear in the time derivative. On the spin chain side, it turns out to be crucial to include the effects of integrating out short wave-length modes. In this way we gain a better understanding of how (a subsector of) the string sigma model emerges from the dual gauge theory, allowing us to demonstrate the duality beyond comparing particular examples of states with large J
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.)
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.)
Renormalization and effective actions for general relativity
International Nuclear Information System (INIS)
Neugebohrn, F.
2007-05-01
Quantum gravity is analyzed from the viewpoint of the renormalization group. The analysis is based on methods introduced by J. Polchinski concerning the perturbative renormalization with flow equations. In the first part of this work, the program of renormalization with flow equations is reviewed and then extended to effective field theories that have a finite UV cutoff. This is done for a scalar field theory by imposing additional renormalization conditions for some of the nonrenormalizable couplings. It turns out that one so obtains a statement on the predictivity of the effective theory at scales far below the UV cutoff. In particular, nonrenormalizable theories can be treated without problems in the proposed framework. In the second part, the standard covariant BRS quantization program for Euclidean Einstein gravity is applied. A momentum cutoff regularization is imposed and the resulting violation of the Slavnov-Taylor identities is discussed. Deriving Polchinski's renormalization group equation for Euclidean quantum gravity, the predictivity of effective quantum gravity at scales far below the Planck scale is investigated with flow equations. A fine-tuning procedure for restoring the violated Slavnov-Taylor identities is proposed and it is argued that in the effective quantum gravity context, the restoration will only be accomplished with finite accuracy. Finally, the no-cutoff limit of Euclidean quantum gravity is analyzed from the viewpoint of the Polchinski method. It is speculated whether a limit with nonvanishing gravitational constant might exist where the latter would ultimatively be determined by the cosmological constant and the masses of the elementary particles. (orig.)
Renormalization and effective actions for general relativity
Energy Technology Data Exchange (ETDEWEB)
Neugebohrn, F.
2007-05-15
Quantum gravity is analyzed from the viewpoint of the renormalization group. The analysis is based on methods introduced by J. Polchinski concerning the perturbative renormalization with flow equations. In the first part of this work, the program of renormalization with flow equations is reviewed and then extended to effective field theories that have a finite UV cutoff. This is done for a scalar field theory by imposing additional renormalization conditions for some of the nonrenormalizable couplings. It turns out that one so obtains a statement on the predictivity of the effective theory at scales far below the UV cutoff. In particular, nonrenormalizable theories can be treated without problems in the proposed framework. In the second part, the standard covariant BRS quantization program for Euclidean Einstein gravity is applied. A momentum cutoff regularization is imposed and the resulting violation of the Slavnov-Taylor identities is discussed. Deriving Polchinski's renormalization group equation for Euclidean quantum gravity, the predictivity of effective quantum gravity at scales far below the Planck scale is investigated with flow equations. A fine-tuning procedure for restoring the violated Slavnov-Taylor identities is proposed and it is argued that in the effective quantum gravity context, the restoration will only be accomplished with finite accuracy. Finally, the no-cutoff limit of Euclidean quantum gravity is analyzed from the viewpoint of the Polchinski method. It is speculated whether a limit with nonvanishing gravitational constant might exist where the latter would ultimatively be determined by the cosmological constant and the masses of the elementary particles. (orig.)
Introduction to string field theory. A pedestrian approach to the covariant formulation
International Nuclear Information System (INIS)
West, G.B.
1986-01-01
A relatively elementary account is given of what a string field represents and what is involved in the construction of its covariant action. Emphasis is on drawing a correspondence with similar problems in ordinary field theory and, particularly, using the language and mathematics used in ordinary field theory. Only the free string is discussed. 17 refs., 3 figs
Introduction to string field theory. A pedestrian approach to the covariant formulation
Energy Technology Data Exchange (ETDEWEB)
West, G.B.
1986-01-01
A relatively elementary account is given of what a string field represents and what is involved in the construction of its covariant action. Emphasis is on drawing a correspondence with similar problems in ordinary field theory and, particularly, using the language and mathematics used in ordinary field theory. Only the free string is discussed. 17 refs., 3 figs. (LEW)
Characterization of binary string statistics for syntactic landmine detection
Nasif, Ahmed O.; Mark, Brian L.; Hintz, Kenneth J.
2011-06-01
Syntactic landmine detection has been proposed to detect and classify non-metallic landmines using ground penetrating radar (GPR). In this approach, the GPR return is processed to extract characteristic binary strings for landmine and clutter discrimination. In our previous work, we discussed the preprocessing methodology by which the amplitude information of the GPR A-scan signal can be effectively converted into binary strings, which identify the impedance discontinuities in the signal. In this work, we study the statistical properties of the binary string space. In particular, we develop a Markov chain model to characterize the observed bit sequence of the binary strings. The state is defined as the number of consecutive zeros between two ones in the binarized A-scans. Since the strings are highly sparse (the number of zeros is much greater than the number of ones), defining the state this way leads to fewer number of states compared to the case where each bit is defined as a state. The number of total states is further reduced by quantizing the number of consecutive zeros. In order to identify the correct order of the Markov model, the mean square difference (MSD) between the transition matrices of mine strings and non-mine strings is calculated up to order four using training data. The results show that order one or two maximizes this MSD. The specification of the transition probabilities of the chain can be used to compute the likelihood of any given string. Such a model can be used to identify characteristic landmine strings during the training phase. These developments on modeling and characterizing the string statistics can potentially be part of a real-time landmine detection algorithm that identifies landmine and clutter in an adaptive fashion.
E11 must be a symmetry of strings and branes
Directory of Open Access Journals (Sweden)
Alexander G. Tumanov
2016-08-01
Full Text Available We construct the dynamical equations, at low levels, that are contained in the non-linear realisation of the semi-direct product of E11 and its vector representation in five and eleven dimensions. Restricting these equations to contain only the usual fields of supergravity and the generalised space–time to be the usual space–time we find the equations of motion of the five and eleven dimensional maximal supergravity theories. Since this non-linear realisation contains effects that are beyond the supergravity approximation and are thought to be present in an underlying theory we conclude that the low energy effective action of string and branes should possess an E11 symmetry.
Strings and superstrings. Electron linear colliders
International Nuclear Information System (INIS)
Alessandrini, V.; Bambade, P.; Binetruy, P.; Kounnas, C.; Le Duff, J.; Schwimmer, A.
1989-01-01
Basic string theory; strings in interaction; construction of strings and superstrings in arbitrary space-time dimensions; compactification and phenomenology; linear e+e- colliders; and the Stanford linear collider were discussed [fr
Rankin-Selberg methods for closed strings on orbifolds
Angelantonj, Carlo; Pioline, Boris
2013-01-01
In recent work we have developed a new unfolding method for computing one-loop modular integrals in string theory involving the Narain partition function and, possibly, a weak almost holomorphic elliptic genus. Unlike the traditional approach, the Narain lattice does not play any role in the unfolding procedure, T-duality is kept manifest at all steps, a choice of Weyl chamber is not required and the analytic structure of the amplitude is transparent. In the present paper, we generalise this procedure to the case of Abelian Z_N orbifolds, where the integrand decomposes into a sum of orbifold blocks that can be organised into orbits of the Hecke congruence subgroup {\\Gamma}_0(N). As a result, the original modular integral reduces to an integral over the fundamental domain of {\\Gamma}_0(N), which we then evaluate by extending our previous techniques. Our method is applicable, for instance, to the evaluation of one-loop corrections to BPS-saturated couplings in the low energy effective action of closed string mo...
Effective action of softly broken supersymmetric theories
International Nuclear Information System (INIS)
Groot Nibbelink, S.; Nyawelo, T.S
2006-12-01
We study the renormalization of (softly) broken supersymmetric theories at the one loop level in detail. We perform this analysis in a superspace approach in which the supersymmetry breaking interactions are parameterized using spurion insertions. We comment on the uniqueness of this parameterization. We compute the one loop renormalization of such theories by calculating superspace vacuum graphs with multiple spurion insertions. To preform this computation efficiently we develop algebraic properties of spurion operators, that naturally arise because the spurions are often surrounded by superspace projection operators. Our results are general apart from the restrictions that higher super covariant derivative terms and some finite effects due to non-commutativity of superfield dependent mass matrices are ignored. One of the soft potentials induces renormalization of the Kaehler potential. (author)
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.
Energy Technology Data Exchange (ETDEWEB)
Siciliano, E.R.
1998-05-12
Data and supporting documentation were compiled and analyzed for 26 cases of gas grab samples taken during waste-tank core sampling activities between September 1, 1995 and December 31, 1997. These cases were tested against specific criteria to reduce uncertainties associated with in-tank sampling location and conditions. Of the 26 possible cases, 16 qualified as drill-string grab samples most likely to represent recently released waste gases. The data from these 16 ``confirmed`` cases were adjusted to remove non-waste gas contributions from core-sampling activities (argon or nitrogen purge), the atmospheric background, and laboratory sampler preparation (helium). The procedure for subtracting atmospheric, laboratory, and argon purge gases was unambiguous. No reliable method for determining the exact amount of nitrogen purge gas was established. Thus, the final set of ``Adjusted`` drill string gas data for the 6 nitrogen-purged cases had a greater degree of uncertainty than the final results for the 10 argon-purged cases. Including the appropriate amounts of uncertainty, this final set of data was added to the set of high-quality results from the Retained Gas Sampler (RGS), and good agreement was found for the N{sub 2}, H{sub 2}, and N{sub 2}O mole fractions sampled from common tanks. These results indicate that under favorable sampling conditions, Drill-String (DS) grab samples can provide reasonably accurate information about the dominant species of released gas. One conclusion from this set of total gas data is that the distribution of the H{sub 2} mole fractions is bimodal in shape, with an upper bound of 78%.
Zeta Functions, Renormalization Group Equations, and the Effective Action
International Nuclear Information System (INIS)
Hochberg, D.; Perez-Mercader, J.; Molina-Paris, C.; Visser, M.
1998-01-01
We demonstrate how to extract all the one-loop renormalization group equations for arbitrary quantum field theories from knowledge of an appropriate Seeley-DeWitt coefficient. By formally solving the renormalization group equations to one loop, we renormalization group improve the classical action and use this to derive the leading logarithms in the one-loop effective action for arbitrary quantum field theories. copyright 1998 The American Physical Society
Directory of Open Access Journals (Sweden)
Amin Boumenir
2008-07-01
Full Text Available We investigate the existence and representation of transmutations, also known as transformation operators, for strings. Using measure theory and functional analytic methods we prove their existence and study their representation. We show that in general they are not close to unity since their representation does not involve a Volterra operator but rather the eigenvalue parameter. We also obtain conditions under which the transmutation is either a bounded or a compact operator. Explicit examples show that they cannot be reduced to Volterra type operators.
Energy Technology Data Exchange (ETDEWEB)
Shakhobalov, A B; Galiopa, A A; Ponomarev, G V; Ushakov, A M
1981-04-28
A drilling string lifter is suggested which includes a rotating tower installed on a fixed base, hydraulic cylinder and pipe-clamping assembly connected through a chain gear to the drive motor. In order to simplify the design of the hydraulic lifter, the drive motor is installed on a fixed base so that the axis of the outlet shaft of the drive motor coincides with the axis of rotation of the tower. In addition, the axis of rotation of the tower is made in the form of a tubular element, and the outlet shaft of the drive motor is ranged between the tubular element.
International Nuclear Information System (INIS)
Ip, A.K.; Koyanagi, K.; Tarasuk, W.R.
1976-01-01
A method of fabricating rodded fuels suitable for use in pressure tube type reactors and in pressure vessel type reactors is described. Fuel rods are secured as an inner and an outer sub-assembly, each rod attached between mounting rings secured to the rod ends. The two sub-assemblies are telescoped together and positioned by spaced thimbles located between them to provide precise positioning while permittng differential axial movement between the sub-assemblies. Such sub-assemblies are particularly suited for mounting as bundle strings. The method provides particular advantages in the assembly of annular-section fuel pins, which includes booster fuel containing enriched fuel material. (LL)
Perception, action, and Roelofs effect: a mere illusion of dissociation.
Directory of Open Access Journals (Sweden)
Paul Dassonville
2004-11-01
Full Text Available A prominent and influential hypothesis of vision suggests the existence of two separate visual systems within the brain, one creating our perception of the world and another guiding our actions within it. The induced Roelofs effect has been described as providing strong evidence for this perception/action dissociation: When a small visual target is surrounded by a large frame positioned so that the frame's center is offset from the observer's midline, the perceived location of the target is shifted in the direction opposite the frame's offset. In spite of this perceptual mislocalization, however, the observer can accurately guide movements to the target location. Thus, perception is prone to the illusion while actions seem immune. Here we demonstrate that the Roelofs illusion is caused by a frame-induced transient distortion of the observer's apparent midline. We further demonstrate that actions guided to targets within this same distorted egocentric reference frame are fully expected to be accurate, since the errors of target localization will exactly cancel the errors of motor guidance. These findings provide a mechanistic explanation for the various perceptual and motor effects of the induced Roelofs illusion without requiring the existence of separate neural systems for perception and action. Given this, the behavioral dissociation that accompanies the Roelofs effect cannot be considered evidence of a dissociation of perception and action. This indicates a general need to re-evaluate the broad class of evidence purported to support this hypothesized dissociation.
Closed flux tubes and their string description in D=3 1 SU(N) gauge theories
International Nuclear Information System (INIS)
Athenodorou, Andreas; Bringoltz, Barak; Teper, Michael
2010-08-01
We calculate the energy spectrum of a confining flux tube that is closed around a spatial torus, as a function of its length l. We do so for various SU(N) gauge theories in 3+1 dimensions, and for various values of spin, parity and longitudinal momentum. We are able to present usefully accurate results for about 20 of the lightest such states, for a range of l that begins close to the (finite volume) deconfining phase transition at l√σ ∝ 1.6, and extends up to l√σ∝6 (where σ is the string tension). We find that most of these low-lying states are well described by the spectrum of the Nambu-Goto free string theory in flat space-time. Remarkably, this is so not only at the larger values of l, where the gap between the ground state energy and the low-lying excitations becomes small compared to the mass gap, but also down to much shorter lengths where these excitation energies become large compared to √σ, the flux-tube no longer 'looks' anything like a thin string, and an expansion of the effective string action in powers of 1/l no longer converges. All this is for flux in the fundamental representation. We also calculate the k=2 (anti)symmetric ground states and these show larger corrections at small l. So far all this closely resembles our earlier findings in 2+1 dimensions. However, and in contrast to the situation in D=2+1, we also find that there are some states, with J P =0 - quantum numbers, that show large deviations from the Nambu-Goto spectrum. We investigate the possibility that (some of) these states may encode the massive modes associated with the internal structure of the flux tube, and we discuss how the precocious free string behaviour of most states constrains the effective string action, on which much interesting theoretical progress has recently been made. (orig.)
Matrix realization of string algebra axioms and conditions of invariance
International Nuclear Information System (INIS)
Babichev, L.F.; Kuvshinov, V.I.; Fedorov, F.I.
1990-01-01
The matrix representations of Witten's and B-algebras of the field string theory in finite dimensional space of the ghost states are suggested for the case of Virasoro algebra truncated to its SU(1,1) subalgebra. In this case all algebraic operations of Witten's and B-algebras are realized in explicit form as some matrix operations in the graded complex vector space. The structure of string action coincides with the universal non-linear cubic matrix form of action for the gauge field theories. These representations lead to matrix conditions of theory invariance which can be used for finding of the explicit form of corresponding operators of the string algebras. (author)
One-Loop Effective Action in Orbifold Compactifications
Von Gersdorff, Gero
2008-01-01
We employ the covariant background formalism to derive generic expressions for the one-loop effective action in field theoretic orbifold compactifications. The contribution of each orbifold sector is given by the effective action of its fixed torus with a shifted mass matrix. We thus study in detail the computation of the heat kernel on tori. Our formalism manifestly separates UV sensitive (local) from UV-insensitive (nonlocal) renormalization. To exemplify our methods, we study the effective potential of 6d gauge theory as well as kinetic terms for gravitational moduli in 11d supergravity.
Thermal effects on decays of a metastable brane configuration
Energy Technology Data Exchange (ETDEWEB)
Nakai, Yuichiro, E-mail: ynakai@physics.harvard.edu [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Ookouchi, Yutaka [Faculty of Arts and Science & Department of Physics, Kyushu University, Fukuoka 819-0395 (Japan)
2016-11-10
We study thermal effects on a decay process of a false vacuum in type IIA string theory. At finite temperature, the potential of the theory is corrected and also thermally excited modes enhance the decay rate. The false vacuum can accommodate a string-like object. This cosmic string makes the bubble creation rate much larger and causes an inhomogeneous vacuum decay. We investigate thermal corrections to the DBI action for the bubble/string bound state and discuss a thermally assisted tunneling process. We show that thermally excited states enhance the tunneling rate of the decay process, which makes the life-time of the false vacuum much shorter.
Finite temperature effective action, AdS5 black holes, and 1/N expansion
International Nuclear Information System (INIS)
Alvarez-Gaume, Luis; Gomez, Cesar; Liu Hong; Wadia, Spenta R.
2005-01-01
We propose a phenomenological matrix model to study string theory in AdS 5 xS 5 in the canonical ensemble. The model reproduces all the known qualitative features of the theory. In particular, it gives a simple effective potential description of Euclidean black hole nucleation and the tunneling between thermal anti-de Sitter (AdS) and the big black hole. It also has some interesting predictions. We find that there exists a critical temperature at which the Euclidean small black hole undergoes a Gross-Witten phase transition. We identify the phase transition with the Horowitz-Polchinski point where the black hole horizon size becomes comparable to the string scale. The appearance of the Hagedorn divergence of thermal AdS is due to the merger of saddle points corresponding to the Euclidean small black hole and thermal AdS. The merger can be described in terms of a cusp (A 3 ) catastrophe and divergences at the perturbative string level are smoothed out at finite string coupling using standard techniques of catastrophe theory
Early markers of ongoing action-effect learning
Directory of Open Access Journals (Sweden)
Hannes eRuge
2012-11-01
Full Text Available Acquiring knowledge about the relationship between stimulus conditions, one’s own actions, and the resulting consequences or effects, is one prerequisite for intentional action. Previous studies have shown that such contextualized associations between actions and their effects (S-R-E associations can be picked up very quickly. The present study examined how such weakly practiced associations might affect overt behavior during the process of initial learning and during subsequent retrieval, and how these two measures are inter-related. We examined incidental (S-R-E learning in the context of trial-and-error S-R learning and in the context of instruction-based S-R learning. Furthermore, as a control condition, common outcome (CO learning blocks were included in which all responses produced one common sound effect, hence precluding differential (S-R-E learning. Post-learning retrieval of R-E associations was tested by re-using previously produced sound effects as novel imperative stimuli combined with actions that were either compatible or incompatible with the previously encountered R-E mapping. The central result was that the size of the compatibility effect could be predicted by the size of relative response slowing during ongoing learning in the preceding acquisition phase, both in trial-and-error learning and in instruction-based learning. Importantly, this correlation was absent for the common outcome control condition, precluding accounts based on unspecific factors. Instead, the results suggest that differential outcomes are ‘actively’ integrated into action planning and that this takes additional planning time. We speculate that this might be especially true for weakly practiced (S-R-E associations before an initial goal-directed action mode transitions into a more stimulus-based action mode.
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.
Tadpole resummations in string theory
International Nuclear Information System (INIS)
Kitazawa, Noriaki
2008-01-01
While R-R tadpoles should be canceled for consistency, string models with broken supersymmetry generally have uncanceled NS-NS tadpoles. Their presence signals that the background does not solve the field equations, so that these models are in 'wrong' vacua. In this Letter we investigate, with reference to some prototype examples, whether the true values of physical quantities can be recovered resumming the NS-NS tadpoles, hence by an approach that is related to the analysis based on String Field Theory by open-closed duality. We show that, indeed, the positive classical vacuum energy of a Dp-brane of the bosonic string is exactly canceled by the negative contribution arising from tree-level tadpole resummation, in complete agreement with Sen's conjecture on open-string tachyon condensation and with the consequent analysis based on String Field Theory. We also show that the vanishing classical vacuum energy of the SO(8192) unoriented bosonic open-string theory does not receive any tree-level corrections from the tadpole resummation. This result is consistent with the fact that this (unstable) configuration is free from tadpoles of massless closed-string modes, although there is a tadpole of the closed string tachyon. The application of this method to superstring models with broken supersymmetry is also discussed
International Nuclear Information System (INIS)
Iyer, Ramakrishnan; Johnson, Clifford V; Pennington, Jeffrey S
2011-01-01
We uncover a remarkable role that an infinite hierarchy of nonlinear differential equations plays in organizing and connecting certain c-hat <1 string theories non-perturbatively. We are able to embed the type 0A and 0B (A, A) minimal string theories into this single framework. The string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy. We observe that there are several other string-like limits of the system, and conjecture that some of them are type IIA and IIB (A, D) minimal string backgrounds. We explain how these and several string-like special points arise and are connected. In some cases, the framework endows the theories with a non-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.
2001-01-01
String 2 is a series of superconducting magnets that are prototypes of those which will be installed in the LHC. It was cooled down to 1.9 Kelvin on September 14th. On Thursday last week, the dipoles of String 2 were successfully taken to nominal current, 11850 A.
International Nuclear Information System (INIS)
Mandelstam, S.
1986-06-01
Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture
String-localized quantum fields
International Nuclear Information System (INIS)
Mund, Jens; Santos, Jose Amancio dos; Silva, Cristhiano Duarte; Oliveira, Erichardson de
2009-01-01
Full text. The principles of physics admit (unobservable) quantum fields which are localized not on points, but on strings in the sense of Mandelstam: a string emanates from a point in Minkowski space and extends to infinity in some space-like direction. This type of localization might permit the construction of new models, for various reasons: (a) in general, weaker localization implies better UV behaviour. Therefore, the class of renormalizable interactions in the string-localized has a chance to be larger than in the point-localized case; (b) for certain particle types, there are no point-localized (free) quantum fields - for example Anyons in d = 2 + 1, and Wigner's massless 'infinite spin' particles. For the latter, free string-localized quantum fields have been constructed; (c) in contrast to the point-localized case, string-localization admits covariant vector/tensor potentials for fotons and gravitons in a Hilbert space representation with positive energy. We shall present free string-localized quantum fields for various particle types, and some ideas about the perturbative construction of interacting string-localized fields. A central point will be an analogue of gauge theories, completely within a Hilbert space and without ghosts, trading gauge dependence with dependence on the direction of the localization string. In order to discuss renormalizability (item (a)), methods from microlocal analysis (wave front set and scaling degree) are needed. (author)
Schaffer, Karl
2012-01-01
The use of traditional string figures by the Dr. Schaffer and Mr. Stern Dance Ensemble led to experimentation with polyhedral string constructions. This article presents a series of polyhedra made with six loops of three colors which sequence through all the Platonic Solids.