Cosmology of B-L cosmic strings
Jeannerot, R.
2006-01-01
${\\rm B - L}$ cosmic strings form in a wide class of theories beyond the Standard Model which contain a ${\\rm U}(1)_{{\\rm B - L}}$ gauge symmetry. They can form at the end of hybrid inflation and explain, together with inflation, the Cosmic Microwave Background anisotropies and the formation of large scale structure. They can produce Cold Dark Matter in the form of the Lightest SuperParticle and they can be at the origin of the baryon asymmetry of our universe. One major advantage of these me...
Semi-shifted hybrid inflation with B-L cosmic strings
Lazarides, George; Vamvasakis, Achilleas
2008-01-01
We discuss a new inflationary scenario which is realized within the extended supersymmetric Pati-Salam model which yields an acceptable b-quark mass for universal boundary conditions and mu>0 by modestly violating Yukawa unification and leads to new shifted, new smooth, or standard-smooth hybrid inflation. Inflation takes place along a "semi-shifted" classically flat direction on which the U(1)_{B-L} gauge group remains unbroken. After the end of inflation, U(1)_{B-L} breaks spontaneously and a network of local cosmic strings, which contribute a small amount to the curvature perturbation, is produced. We show that, in minimal supergravity, this "semi-shifted" inflationary scenario is compatible with a recent fit to data which uses field-theory simulations of a local string network. Taking into account the requirement of gauge unification, we find that, for spectral index n_s=1, the predicted fractional contribution f_{10} of strings to the temperature power spectrum at multipole l=10 is about 0.039. Also, for...
Sakellariadou, M
2006-01-01
Cosmic strings, a hot subject in the 1980's and early 1990's, lost its appeal when it was found that it leads to inconsistencies in the power spectrum of the measured cosmic microwave background temperature anisotropies. However, topological defects in general, and cosmic strings in particular, are deeply rooted in the framework of grand unified theories. Indeed, it was shown that cosmic strings are expected to be generically formed within supersymmetric grand unified theories. This theoretical support gave a new boost to the field of cosmic strings, a boost which has been recently enhanced when it was shown that cosmic superstrings (fundamental or one-dimensional Dirichlet branes) can play the role of cosmic strings, in the framework of braneworld cosmologies. To build a cosmological scenario we employ high energy physics; inflation and cosmic strings then naturally appear. Confronting the predictions of the cosmological scenario against current astrophysical/cosmological data we impose constraints on its fr...
International Nuclear Information System (INIS)
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
Donaire, M; Rajantie, A.
2005-01-01
We argue that cosmic strings with high winding numbers generally form in first-order gauge symmetry breaking phase transitions, and we demonstrate this using computer simulations. These strings are heavier than single-winding strings and therefore more easily observable. Their cosmological evolution may also be very different.
Semilocal cosmic string networks
International Nuclear Information System (INIS)
We report on a large-scale numerical study of networks of semilocal cosmic strings in flat space in the parameter regime in which they are perturbatively stable. We find a population of segments with an exponential length distribution and indications of a scaling network without significant loop formation. Very deep in the stability regime strings of superhorizon size grow rapidly and ''percolate'' through the box. We believe these should lead at late times to a population of infinite strings similar to topologically stable strings. However, the strings are very light; scalar gradients dominate the energy density, and the network has thus a global texturelike signature. As a result, the observational constraints, at least from the temperature power spectrum of the cosmic microwave background, on models predicting semilocal strings should be closer to those on global textures or monopoles, rather than on topologically stable gauged cosmic strings
Becker, Katrin; Becker, Melanie; Krause, Axel
2005-01-01
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 the...
Nonintercommuting Cosmic Strings
International Nuclear Information System (INIS)
We perform the numerical field evolution for the collision of two Abelian type I cosmic strings. We present evidence that, for collisions at small but characteristic relative velocities and angles, these cosmic strings do not exchange ends and separate. Rather, local higher winding number bound states are formed close to the collision point, which promote multiple local scatterings at right angles and prevent intercommutation from happening. This constitutes the simplest example of the breakdown of the intercommutation rule, usually assumed in the construction of effective models for cosmic string network evolution. copyright 1997 The American Physical Society
Nonintercommuting Cosmic Strings
Energy Technology Data Exchange (ETDEWEB)
Bettencourt, L.M. [The Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Bettencourt, L.M. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, Heidelberg 69120 (Germany); Laguna, P. [Department of Astronomy Astrophysics and Center for Gravitational Physics Geometry, Penn State University, University Park, Pennsylvania 16802 (United States); Matzner, R.A. [Center for Relativity, The University of Texas, Austin, Texas 78712 (United States); Matzner, R.A. [Orson Anderson Scholar, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
1997-03-01
We perform the numerical field evolution for the collision of two Abelian type I cosmic strings. We present evidence that, for collisions at small but characteristic relative velocities and angles, these cosmic strings {ital do not} exchange ends and separate. Rather, local higher winding number bound states are formed close to the collision point, which promote multiple local scatterings at right angles and prevent intercommutation from happening. This constitutes the simplest example of the breakdown of the intercommutation rule, usually assumed in the construction of effective models for cosmic string network evolution. {copyright} {ital 1997} {ital The American Physical Society}
Davis, A. -C.; Kibble, T. W. B.
2005-01-01
Cosmic strings are linear concentrations of energy that may be formed at phase transitions in the very early universe. At one time they were thought to provide a possible origin for the density inhomogeneities from which galaxies eventually develop, though this idea has been ruled out, primarily by observations of the cosmic microwave background (CMB). Fundamental strings are the supposed building blocks of all matter in superstring theory or its modern version, M-theory. These two concepts w...
Kibble, T. W. B.
2004-01-01
There are two main reasons for the recent renewal of interest in cosmic strings: Fundamental string-theory models suggest their existence; and there are at least two tentative observations of their possible effects. In this talk, I review their current status in the light of these two factors.
International Nuclear Information System (INIS)
We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≅10-18 m. The vacuum remains stable in our model, because neutral strings are not energetically favored.
Stable charged cosmic strings.
Weigel, H; Quandt, M; Graham, N
2011-03-11
We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18) m. The vacuum remains stable in our model, because neutral strings are not energetically favored. PMID:21469786
Cosmic Strings and Quintessence
Institute of Scientific and Technical Information of China (English)
段一士; 任继荣; 杨捷
2003-01-01
Using torsion two-form we present a new Lorentz gauge invariant U (1) topological field theory in Riemann-Cartan space-time manifold U4. By virtue of the decomposition theory of U(1) gauge potential and the φ-mapping topological current theory, it is proven that the U(1) complex scalar field φ(x) can be looked upon as the order parameter field in our Universe, and a set of zero points of φ(x) create the cosmic strings as the space-time defects in the early Universe. In the standard cosmology, this complex scalar order parameter field possesses negative pressure, provides an accelerating expansion of Universe, and be able to explain the inflation in the early Universe. Therefore this complex scalar field is not only the order parameter field created the cosmic strings in the early universe, but also reasonably behaves as the quintessence, the dark energy.
Reconnection of Colliding Cosmic Strings
Hanany, Amihay; Hashimoto, Koji
2005-01-01
For vortex strings in the Abelian Higgs model and D-strings in superstring theory, both of which can be regarded as cosmic strings, we give analytical study of reconnection (recombination, inter-commutation) when they collide, by using effective field theories on the strings. First, for the vortex strings, via a string sigma model, we verify analytically that the reconnection is classically inevitable for small collision velocity and small relative angle. Evolution of the shape of the reconne...
Clément, Gérard
1995-01-01
We construct regular multi-wormhole solutions to a gravitating $\\sigma$ model in three space-time dimensions, and extend these solutions to cylindrical traversable wormholes in four and five dimensions. We then discuss the possibility of identifying wormhole mouths in pairs to give rise to Wheeler wormholes. Such an identification is consistent with the original field equations only in the absence of the $\\sigma$-model source, but with possible naked cosmic string sources. The resulting Wheel...
Cosmic strings and skyrmion decay
International Nuclear Information System (INIS)
This paper reports on the Callan-Witten picture for monopole catalyzed skyrmion decay which is developed in order to analyze the corresponding cosmic string scenario. The authors find that cosmic strings (both ordinary and superconducting) can catalyze proton decay, but that this catalysis only occurs on the scale of the core of the string. An argument is also given for the difference in the enhancement factors for monopoles and strings
Electroweak Baryogenesis with Cosmic Strings ?
Espinosa, J. R.
1999-01-01
I report on a critical analysis of the scenario of electroweak baryogenesis mediated by nonsuperconducting cosmic strings. This mechanism relies upon electroweak symmetry restoration in a region around cosmic strings, where sphalerons would be unsuppressed. I discuss the various problems this scenario has to face, presenting a careful computation of the sphaleron rates inside the strings, of the chemical potential for chiral number and of the efficiency of baryogenesis in different regimes of...
Racetrack inflation and cosmic strings
International Nuclear Information System (INIS)
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.)
Test particle trajectories near cosmic strings
Indian Academy of Sciences (India)
Farook Rahaman; Subenoy Chakraborty; K Maity
2002-01-01
We present a detailed analysis of the motion of test particle in the gravitational ﬁeld of cosmic strings in different situations using the Hamilton–Jacobi (H–J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans–Dicke theory and cosmic string in dilaton gravity.
Evolution of cosmic string networks
International Nuclear Information System (INIS)
We summarize our new results on cosmic strings. These results include: the application of non-equilibrium statistical mechanics to cosmic string evolution, a simple ''one scale'' model for the long strings which has a great deal of predictive power, results from large scale numerical simulations, and a discussion of the observational consequences of our results. An upper bond on Gμ of approximately 10-7 emerges from the millisecond pulsar gravity wave bound. We discuss how numerical uncertainties affect this. Any changes which weaken the bound would probably also give the long strings the dominant role in producing observational consequences. 22 refs
Cosmic Strings with Small Tension
Halyo, Edi
2009-01-01
We describe cosmic F--term strings with exponentially small tension which are D3 branes wrapped on deformed $A_3$ singularities. We show that brane instanton effects which can be calculated after a geometric transition give rise to an exponentially small volume for the node on which the D3 branes wrap leading to a string with small tension. We generalize our description to the case of non--Abelian cosmic strings and argue that these strings are stable against monopole--anti monopole pair creation.
Cosmic necklaces from string theory
International Nuclear Information System (INIS)
We present the properties of a cosmic superstring network in the scenario of flux compactification. An infinite family of strings, the (p,q) strings, are allowed to exist. The flux compactification leads to a string tension that is periodic in p. Monopoles, appearing here as beads on a string, are formed in certain interactions in such networks. This allows bare strings to become cosmic necklaces. We study network evolution in this scenario, outlining what conditions are necessary to reach a cosmologically viable scaling solution. We also analyze the physics of the beads on a cosmic necklace, and present general conditions for which they will be cosmologically safe, leaving the network's scaling undisturbed. In particular, we find that a large average loop size is sufficient for the beads to be cosmologically safe. Finally, we argue that loop formation will promote a scaling solution for the interbead distance in some situations
International Nuclear Information System (INIS)
This paper discusses the following topics: 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; and Electromagnetic radiation from the conversion of Nambu-Goldstone bosons in astrophysical magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Sikivie, P. (Florida Univ., Gainesville, FL (USA). Dept. of Physics)
1990-01-01
This paper discusses the following topics: 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; and Electromagnetic radiation from the conversion of Nambu-Goldstone bosons in astrophysical magnetic fields.
Radially stabilized inflating cosmic strings
Niedermann, Florian; Schneider, Robert
2015-03-01
In general relativity, local cosmic strings are well known to produce a static, locally flat spacetime with a wedge removed. If the tension exceeds a critical value, the deficit angle becomes larger than 2 π , leading to a compact exterior that ends in a conical singularity. In this paper, we investigate dynamical solutions for cosmic strings with super-critical tensions. To this end, we model the string as a cylindrical shell of finite and stabilized transverse width and show that there is a marginally super-critical regime in which the stabilization can be achieved by physically reasonable matter. We show numerically that the static deficit angle solution is unstable for super-critical string tensions. Instead, the geometry starts expanding in the axial direction at an asymptotically constant rate, and a horizon is formed in the exterior spacetime, which has the shape of a growing cigar. We are able to find the analytic form of the attractor solution describing the interior of the cosmic string. In particular, this enables us to analytically derive the relation between the string tension and the axial expansion rate. Furthermore, we show that the exterior conical singularity can be avoided for dynamical solutions. Our results might be relevant for theories with two extra dimensions, modeling our Universe as a cosmic string with a three-dimensional axis. We derive the corresponding Friedmann equation, relating the on-brane Hubble parameter to the string tension or, equivalently, brane cosmological constant.
Fermionic Zero Modes of Supergravity Cosmic Strings
Brax, Ph.; BRUCK, C.; Davis, A C; Davis, Stephen C.
2006-01-01
Recent developments in string theory suggest that cosmic strings could be formed at the end of brane inflation. Supergravity provides a realistic model to study the properties of strings arising in brane inflation. Whilst the properties of cosmic strings in flat space-time have been extensively studied there are significant complications in the presence of gravity. We study the effects of gravitation on cosmic strings arising in supergravity. Fermion zero modes are a common feature of cosmic ...
Cosmic Strings and the String Dilaton
International Nuclear Information System (INIS)
The existence of a dilaton (or moduli) with gravitational-strength coupling to matter imposes stringent constraints on the allowed energy scale of cosmic strings, η. In particular, superheavy gauge strings with η∼1016GeV are ruled out unless the dilaton mass mφ approx-gt 100TeV , while the currently popular value mφ∼1TeV imposes the bound η approx-lt 3x1011GeV . Some nonstandard cosmological scenarios which can avoid these constraints are pointed out. copyright 1997 The American Physical Society
Cosmic Strings and the String Dilaton
Damour, Thibault; Vilenkin, Alexander(Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155, U.S.A.)
1996-01-01
The existence of a dilaton (or moduli) with gravitational-strength coupling to matter imposes stringent constraints on the allowed energy scale of cosmic strings, $\\eta$. In particular, superheavy gauge strings with $\\eta \\sim 10^{16} GeV$ are ruled out unless the dilaton mass $m_{\\phi} \\gsim 100 TeV$, while the currently popular value $m_{\\phi} \\sim 1 TeV$ imposes the bound $\\eta \\lsim 3 \\times 10^{11} GeV$. Similar constraints are obtained for global topological defects. Some non-standard c...
Black holes as beads on cosmic strings
Ashoorioon, Amjad; B. Mann, Robert
2014-01-01
We consider the possibility of formation of cosmic strings with black holes as beads. We focus on the simplest setup where two black holes are formed on a long cosmic string. It turns out the in absence of a background magnetic field and for observationally viable values for cosmic string tensions, $\\mu
Radially stabilized inflating cosmic strings
Niedermann, Florian
2014-01-01
In General Relativity, cosmic strings are well known to produce a static, locally flat spacetime with a wedge removed. If the tension exceeds a critical value, the deficit angle becomes larger than $ 2\\pi $, leading to a compact exterior that ends in a conical singularity. In this work, we investigate dynamical solutions for cosmic strings with super-critical tensions. To this end, we model the string as a cylindrical shell of finite and stabilized transverse width and show that there is a marginally super-critical regime in which the stabilization can be achieved by physically reasonable matter. We show numerically that the static deficit angle solution is unstable for super-critical string tensions. Instead, the geometry starts expanding in axial direction at an asymptotically constant rate, and a horizon is formed in the exterior, which has the shape of a growing cigar. We are able to find the analytic form of the attractor solution describing the interior of the cosmic string. In particular, this enables ...
Fireballs from Superconducting Cosmic Strings
Gruzinov, Andrei
2016-01-01
Thermalized fireballs should be created by cusp events on superconducting cosmic strings. This simple notion allows to reliably estimate particle emission from the cusps in a given background magnetic field. With plausible assumptions about intergalactic magnetic fields, the cusp events can produce observable fluxes of high-energy photons and neutrinos with unique signatures.
Quantum Stabilization of Cosmic Strings
Weigel, H; Graham, N
2015-01-01
In the standard model, stabilization of a classically unstable cosmic string may occur through the quantum fluctuations of a heavy fermion doublet. We review numerical results from a semiclassical expansion in a reduced version of the standard model. In this expansion the leading quantum corrections emerge at one loop level for many internal degrees of freedom. The resulting vacuum polarization energy and the binding energy of occupied fermion energy levels are of the same order, and must therefore be treated on equal footing. Populating these bound states lowers the total energy compared to the same number of free fermions. Charged strings are already stabilized for a fermion mass only somewhat larger than the top quark mass. Though obtained in a reduced version these results suggest that neither extraordinarily large fermion masses nor unrealistic couplings are required to bind a cosmic string in the standard model. Furthermore we also review results for a quantum stabilization mechanism that prevents close...
Vector superconductivity in cosmic strings
International Nuclear Information System (INIS)
We argue that in most realistic cases, the usual Witten-type bosonic superconductivity of the cosmic string is automatically (independent of the existence of superconducting currents) accompanied by the condensation of charged gauge vector bosons in the core giving rise to a new vector type superconductivity. The value of the charged vector condensate is related with the charged scalar expectation value, and vanishes only if the latter goes to zero. The mechanism for the proposed vector superconductivity, differing fundamentally from those in the literature, is delineated using the simplest realistic example of the two Higgs doublet standard model interacting with the extra cosmic string. It is shown that for a wide range of parameters, for which the string becomes scalarly superconducting, W boson condensates (the sources of vector superconductivity) are necessarily excited. (author). 14 refs
A Cosmic String Specific Signature on the Cosmic Microwave Background
Moessner, R; Perivolaropoulos, L.; Brandenberger, R.
1993-01-01
Using an analytical model for the string network we show that the kurtosis of cosmic microwave background (CMB) temperature gradient maps is a good statistic to distinguish between the cosmic string model and inflationary models of structure formation. The difference between the stringy and inflationary value for the kurtosis is inversely proportional to the angular resolution and to the number of strings per Hubble volume of the strings' scaling solution. If strings are indeed responsible fo...
Duality relation between charged elastic strings and superconducting cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Carter, B.
1989-06-23
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.).
D-term inflation without cosmic strings
International Nuclear Information System (INIS)
We present a superstring-inspired version of D-term inflation that does not lead to cosmic string formation and appears to satisfy the current cosmic microwave background constraints. It differs from minimal D-term inflation by a second pair of charged superfields that makes the strings nontopological (semilocal). The strings are also Bogomol'nyi-Prasad-Sommerfield strings, so the scenario is expected to survive supergravity corrections. The second pair of charged superfields arises naturally in several brane and conifold scenarios, but its effect on cosmic string formation had not been noticed so far
Peeling U(1)-gauge cosmic strings
International Nuclear Information System (INIS)
We numerically investigate collisions of cosmic strings carrying different winding numbers. We find that for strings with winding numbers n1 and n2, intercommutation occurs by peeling a string of winding number chemical bondn1-n2chemical bond from the string with the larger winding number. The resulting string connects the original colliding strings to form a state of three joined strings, but because of the peeling the eventual result is a reduction in the winding numbers of the network. Stable astrophysical strings with large winding number are thus unlikely to persist. All simulations have gauge/scalar-field mass ratio = 2. .AE
Peeling U(1)-gauge cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Laguna, P.; Matzner, R.A.
1989-04-24
We numerically investigate collisions of cosmic strings carrying different winding numbers. We find that for strings with winding numbers n/sub 1/ and n/sub 2/, intercommutation occurs by peeling a string of winding number chemically bondn/sub 1/-n/sub 2/chemically bond from the string with the larger winding number. The resulting string connects the original colliding strings to form a state of three joined strings, but because of the peeling the eventual result is a reduction in the winding numbers of the network. Stable astrophysical strings with large winding number are thus unlikely to persist. All simulations have gauge/scalar-field mass ratio = 2. .AE
Inflation, cosmic strings, and galaxy formation
International Nuclear Information System (INIS)
Inflationary universe models and the cosmic string theory provide two distinct ways to explain the origin of inhomogeneities in the universe on large scales. I shall summarize and compare the two mechanisms for the origin of galaxies and clusters of galaxies, and mention some recent results on galaxy formation with hot dark matter and cosmic strings. (author)
CMB Constraints on Cosmic Strings and Superstrings
Charnock, Tom; Copeland, Edmund J; Moss, Adam
2016-01-01
We present the first complete MCMC analysis of cosmological models with evolving cosmic (super)string networks, using the Unconnected Segment Model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on {\\Lambda}CDM and string network parameters, namely the string tension G{\\mu}, the loop-chopping efficiency c_r and the string wiggliness {\\alpha}. For cosmic superstrings, we obtain joint constraints on the fundamental string tension G{\\mu}_F, the string coupling g_s, the self-interaction coefficient c_s, and the volume of compact extra dimensions w. This constitutes the most comprehensive CMB analysis of {\\Lambda}CDM cosmology + strings to date. For ordinary cosmic string networks our updated constraint on the string tension is, in relativistic units, G{\\mu}<1.1x10^-7, while for cosmic superstrings our constraint on the fundamental string tension is G{\\mu}_F<2.8x10^-8, both obtained using Planck2015 temperature and polarisation data.
CMB constraints on cosmic strings and superstrings
Charnock, Tom; Avgoustidis, Anastasios; Copeland, Edmund J.; Moss, Adam
2016-06-01
We present the first complete Markov chain Monte Carlo analysis of cosmological models with evolving cosmic (super)string networks, using the unconnected segment model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constraints on Λ cold dark matter (CDM) and string network parameters, namely the string tension G μ , the loop-chopping efficiency cr, and the string wiggliness α . For cosmic superstrings, we obtain joint constraints on the fundamental string tension G μF, the string coupling gs, the self-interaction coefficient cs, and the volume of compact extra dimensions w . This constitutes the most comprehensive CMB analysis of Λ CDM cosmology+strings to date. For ordinary cosmic string networks our updated constraint on the string tension, obtained using Planck2015 temperature and polarization data, is G μ <1.1 ×10-7 in relativistic units, while for cosmic superstrings our constraint on the fundamental string tension after marginalizing over gs, cs, and w is G μF<2.8 ×10-8.
Gravitational Scattering Of Photons Off Cosmic Strings
Chu, Yi-Zen
2013-01-01
Photons can gravitationally scatter off a cosmic string loop and gain or lose energy. We consider the spectral distortion induced by cosmic string loops placed in an ambient thermal bath of photons. The fractional deviation from a thermal spectrum caused by cosmic strings is estimated to scale as (G_N \\mu)^2 z^2, where G_N is Newton's constant, $\\mu$ is the string tension, and z is the cosmological redshift after which spectral distortions can survive. This effect is large enough to potentially be of observational interest.
Metastable cosmic strings in realistic models
International Nuclear Information System (INIS)
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
Black holes as beads on cosmic strings
International Nuclear Information System (INIS)
We consider the possibility of the formation of cosmic strings with black holes as beads. We focus on the simplest setup where two black holes are formed on a long cosmic string. It turns out that in the absence of a background magnetic field and for observationally viable values for cosmic string tensions, μ<2×10−7, the tension of the strut in between the black holes has to be less than the ones that run into infinity. This result does not change if a cosmological constant is present. However, if a background magnetic field is turned on, we can have stable setups where the tensions of all cosmic strings are equal. We derive the equilibrium conditions in each of these setups depending on whether the black holes are extremal or non-extremal. We obtain cosmologically acceptable solutions with solar mass black holes and an intragalactic-strength cosmic magnetic field. (paper)
Constraints on Cosmic Strings due to Black Holes Formed from Collapsed Cosmic String Loops
Caldwell, R. R.; Gates, E.
1993-01-01
The cosmological features of primordial black holes formed from collapsed cosmic string loops are studied. Observational restrictions on a population of primordial black holes are used to restrict $f$, the fraction of cosmic string loops which collapse to form black holes, and $\\mu$, the cosmic string mass-per-unit-length. Using a realistic model of cosmic strings, we find the strongest restriction on the parameters $f$ and $\\mu$ is due to the energy density in $100 MeV$ photons radiated by t...
Particle creation if a cosmic string snaps
Bilge, A H; Ozdemir, N; Bilge, A H; Hortacsu, M; Ozdemir, N
1994-01-01
We calculate the Bogolubov coefficients for a metric which describes the snapping of a cosmic string. If we insist on a matching condition for all times {\\it and} a particle interpretation, we find no particle creation.
Constraints on cosmic strings from ultracompact minihalos
Anthonisen, Madeleine; Scott, Pat
2015-01-01
Cosmic strings are expected to form loops. These can act as seeds for accretion of dark matter, leading to the formation of ultracompact minihalos (UCMHs). We perform a detailed study of the accretion of dark matter onto cosmic string loops and compute the resulting mass distribution of UCMHs. We then apply observational limits on the present-day abundance of UCMHs to derive corresponding limits on the cosmic string tension $G\\mu$. The bounds are strongly dependent upon the assumed distribution of loop velocities and their impacts on UCMH formation. Under the assumption that a loop can move up to a thousand times its own radius and still form a UCMH, we find a limit of $G\\mu\\le 5\\times10^{-8}$. We show, in opposition to previous results, that strong limits on the cosmic string tension are not obtainable from UCMHs when more stringent (and realistic) requirements are placed on loop velocities.
Flux-Confinement in Dilatonic Cosmic Strings
G.W. Gibbons; Wells, C. G.
1993-01-01
We study dilaton-electrodynamics in flat spacetime and exhibit a set of global cosmic string like solutions in which the magnetic flux is confined. These solutions continue to exist for a small enough dilaton mass but cease to do so above a critcal value depending on the magnetic flux. There also exist domain wall and Dirac monopole solutions. We discuss a mechanism whereby magnetic monopolesmight have been confined by dilaton cosmic strings during an epoch in the early universe during which ...
Higher order intercommutations in Cosmic String Collisions
Achúcarro, A.; Verbiest, G. J.
2010-01-01
We report the first observation of multiple intercommutation (more than two successive reconnections) of cosmic strings at ultra-high collision speeds, and the formation of ``kink trains'' with up to four closely spaced left- or right-moving kinks. We performed a flat space numerical study of abelian Higgs cosmic string intercommutation in the type-II regime $\\beta > 1$ (where $\\beta = m^2_{scalar} / m^2_{gauge}$) up to $\\beta = 64$, the highest value investigated to date. Our results confirm...
Long range effects of cosmic string structure
Allen, B; Ottewill, A C; Allen, Bruce; Kay, Bernard S; Ottewill, Adrian C
1996-01-01
We combine and further develop ideas and techniques of Allen \\& Ottewill, Phys. Rev.D, {\\bf 42}, 2669 (1990) and Kay \\& Studer Commun. Math. Phys., {\\bf 139}, 103 (1991) for calculating the long range effects of cosmic string cores on classical and quantum field quantities far from an (infinitely long, straight) cosmic string. We find analytical approximations for (a) the gravity-induced ground state renormalized expectation values of \\hat\\varphi^2 and \\hat T_\\mu{}^\
Wave diffraction by a cosmic string
Fernández-Núñez, Isabel
2016-01-01
We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects.
Hiramatsu, Takashi; Sendouda, Yuuiti; Takahashi, Keitaro; Yamauchi, Daisuke; Yoo, Chul-Moon
2013-01-01
We study the network of Type-I cosmic strings using the field-theoretic numerical simulations in the Abelian-Higgs model. For Type-I strings, the gauge field plays an important role, and thus we find that the correlation length of the strings is strongly dependent upon the parameter \\beta, the ratio between the self-coupling constant of the scalar field and the gauge coupling constant, namely, \\beta=\\lambda/2e^2. In particular, if we take the cosmic expansion into account, the network becomes...
Gamma Ray Signatures from Ordinary Cosmic Strings
MacGibbon, Jane H.; Brandenberger, Robert H.
1992-01-01
We calculate the flux of ultra high energy photons from individual ordinary (i.e. non-superconducting) cosmic strings and compare the results with the sensitivity of current and proposed TeV and EeV telescopes. Our calculations give only upper limits for the gamma ray flux, since the source of the photons, jets from particle production at cusps, may be weakened by back reaction effects. For the usual cosmic distribution of strings, the predicted bursts from strings with the value of mass per ...
Wave diffraction by a cosmic string
Fernández-Núñez, Isabel; Bulashenko, Oleg
2016-08-01
We show that if a cosmic string exists, it may be identified through characteristic diffraction pattern in the energy spectrum of the observed signal. In particular, if the string is on the line of sight, the wave field is shown to fit the Cornu spiral. We suggest a simple procedure, based on Keller's geometrical theory of diffraction, which allows to explain wave effects in conical spacetime of a cosmic string in terms of interference of four characteristic rays. Our results are supposed to be valid for scalar massless waves, including gravitational waves, electromagnetic waves, or even sound in case of condensed matter systems with analogous topological defects.
Supermassive screwed cosmic string in dilaton gravity
Bezerra, V B; Cuesta, H J M; Bezerra, Valdir B.; Ferreira, Cristine N.; Cuesta, Herman J. Mosquera
2006-01-01
The early Universe might have undergone phase transitions at energy scales much higher than the one corresponding to the Grand Unified Theories (GUT) scales. Then, at these higher energy scales, the transition at which gravity separated from all other interactions, the Planck era, more massive strings called supermassive cosmic strings, could be produced, with energy of about 10^{19}GeV. The dynamics of strings formed with this energy scale cannot be described by means of the weak-field approximation, as in the standard procedure for ordinary GUT cosmic strings. As suggested by string theories, at this extreme energies, gravity may be transmitted by some kind of scalar field (usually called the dilaton in addition to the tensor field of Einstein's theory of gravity. In this framework is then permissible to tackle the question regarding the dynamics of supermassive cosmic strings that may arise at this energy scale. With this aim we obtain the gravitational field of a supermassive screwed cosmic string in a sc...
Cosmic Strings Stabilized by Fermion Fluctuations
Weigel, H; Graham, N
2011-01-01
We provide a thorough exposition of recent results on the quantum stabilization of cosmic strings. Stabilization occurs through the coupling to a heavy fermion doublet in a reduced version of the standard model. The study combines the vacuum polarization energy of fermion zero-point fluctuations and the binding energy of occupied energy levels, which are of the same order in a semi-classical expansion. Populating these bound states assigns a charge to the string. Strings carrying fermion charge become stable if the Higgs and gauge fields are coupled to a fermion that is less than twice as heavy as the top quark. The vacuum remains stable in the model, because neutral strings are not energetically favored. These findings suggest that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model.
Cosmic-string loops are straight
International Nuclear Information System (INIS)
It is shown that a loop of idealized cosmic string deforms the background geometry in its vicinity so that its path and shape become geodesics of this background. For angular deficits smaller than π, this deformation causes the background curvature to grow without bound near an infinitely thin string. However, the rate of growth is so weak that the tidal forces are not yet appreciable at the surface of a grand-unification string. Although equations of motion for the string in a ''background'' geometry cannot be defined in a clear-cut fashion, they are not inconsistent with the conventional dynamics derived from the Nambu action
Effects of cosmic strings on free streaming
International Nuclear Information System (INIS)
We study the effect of free streaming in a universe with cosmic strings with time-varying tension as well as with constant tension. Although current cosmological observations suggest that fluctuation seeded by cosmic strings cannot be the primary source of cosmic density fluctuation, some contributions from them are still allowed. Since cosmic strings actively produce isocurvature fluctuation, the damping of small scale structure via free streaming by dark matter particles with large velocity dispersion at the epoch of radiation-matter equality is less efficient than that in models with conventional adiabatic fluctuation. We discuss its implications to the constraints on the properties of particles such as massive neutrinos and warm dark matter
Effects of Cosmic Strings on Free Streaming
Takahashi, T; Takahashi, Tomo; Yamaguchi, Masahide
2006-01-01
We study the effect of free streaming in a universe with cosmic strings with time-varying tension as well as with constant tension. Although current cosmological observations suggest that fluctuation seeded by cosmic strings cannot be the primary source of cosmic density fluctuation, some contributions from them are still allowed. Since cosmic strings actively produce isocurvature fluctuation, the damping of small scale structure via free streaming by dark matter particles with large velocity dispersion at the epoch of radiation-matter equality is less efficient than that in models with conventional adiabatic fluctuation. We discuss its implications to the constraints on the properties of particles such as massive neutrinos and warm dark matter.
Cosmic Microwave Background spectral distortions from cosmic string loops
Anthonisen, Madeleine; Brandenberger, Robert; Laguë, Alex; Morrison, Ian A.; Xia, Daixi
2016-02-01
Cosmic string loops contain cusps which decay by emitting bursts of particles. A significant fraction of the released energy is in the form of photons. These photons are injected non-thermally and can hence cause spectral distortions of the Cosmic Microwave Background (CMB). Under the assumption that cusps are robust against gravitational back-reaction, we compute the fractional energy density released as photons in the redshift interval where such non-thermal photon injection causes CMB spectral distortions. Whereas current constraints on such spectral distortions are not strong enough to constrain the string tension, future missions such as the PIXIE experiment will be able to provide limits which rule out a range of string tensions between G μ ~ 10-15 and G μ ~ 10-12, thus ruling out particle physics models yielding these kind of intermediate-scale cosmic strings.
Cosmic Microwave Background Spectral Distortions from Cosmic String Loops
Anthonisen, Madeleine; Laguë, Alex; Morrison, Ian A; Xia, Daixi
2015-01-01
Cosmic string loops contain cusps which decay by emitting bursts of particles. A significant fraction of the released energy is in the form of photons. These photons are injected non-thermally and can hence cause spectral distortions of the Cosmic Microwave Background (CMB). Under the assumption that cusps are robust against gravitational back-reaction, we compute the fractional energy density released as photons in the redshift interval where such non-thermal photon injection causes CMB spectral distortions. Whereas current constraints on such spectral distortions are not strong enough to constrain the string tension, future missions such as the PIXIE experiment will be able to provide limits which rule out a range of string tensions between $G \\mu \\sim 10^{-15}$ and $G \\mu \\sim 10^{-12}$, thus ruling out particle physics models yielding these kind of intermediate-scale cosmic strings.
Cosmic microwave anisotropies from BPS semilocal strings
Urrestilla, Jon; Hindmarsh, Mark; Kunz, Martin; Liddle, Andrew R
2007-01-01
We present the first ever calculation of cosmic microwave background CMB anisotropy power spectra from semilocal cosmic strings, obtained via simulations of a classical field theory. Semilocal strings are a type of non-topological defect arising in some models of inflation motivated by fundamental physics, and are thought to relax the constraints on the symmetry breaking scale as compared to models with (topological) cosmic strings. We derive constraints on the model parameters, including the string tension parameter mu, from fits to cosmological data, and find that in this regard BPS semilocal strings resemble textures more than topological strings. The observed microwave anisotropy at l=10 is reproduced if Gmu = 4.9x10^{-6} (G is Newton's constant). However as with other defects the spectral shape does not match observations, and in models with inflationary perturbations plus semilocal strings the 95% confidence level upper bound is Gmu<1.9x10^{-6} when CMB data, Hubble Key Project and Big Bang Nucleosyn...
CMB temperature bispectrum induced by cosmic strings
International Nuclear Information System (INIS)
The cosmic microwave background (CMB) bispectrum of the temperature anisotropies induced by a network of cosmic strings is derived for small angular scales, under the assumption that the principal cause of temperature fluctuations is the Gott-Kaiser-Stebbins effect. We provide analytical expressions for all isosceles triangle configurations in Fourier space. Their overall amplitude is amplified as the inverse cube of the angle and diverges for flat triangles. The isosceles configurations generically lead to a negative bispectrum with a power-law decay l-6 for large multipole l. However, collapsed triangles are found to be associated with a positive bispectrum whereas the squeezed triangles still exhibit negative values. We then compare our analytical estimates to a direct computation of the bispectrum from a set of 300 statistically independent temperature maps obtained from Nambu-Goto cosmic string simulations in a Friedmann-Lemaitre-Robertson-Walker universe. We find good agreement for the overall amplitude, the power-law behavior, and the angle dependency of the various triangle configurations. At l∼500 the cosmic string Gott-Kaiser-Stebbins effect contributes approximately the same equilateral CMB bispectrum amplitude as an inflationary model with |fNLloc|≅103, if the strings contribute about 10% of the temperature power spectrum at l=10. Current bounds on fNL are not derived using cosmic string bispectrum templates, and so our fNL estimate cannot be used to derive bounds on strings. However it does suggest that string bispectrum templates should be included in the search of CMB non-Gaussianities.
Wiggly cosmic strings accrete dark energy
Gonzalez-Diaz, Pedro F.; Madrid, Jose A. Jimenez
2005-01-01
This paper deals with a study of the cylindrically symmetric accretion of dark energy with equation of state $p=w\\rho$ onto wiggly straight cosmic strings. We have obtained that when $w>-1$ the linear energy density in the string core gradually increases tending to a finite maximum value as time increases for all considered dark energy models. On the regime where the dominant energy condition is violated all such models predict a steady decreasing of the linear energy density of the cosmic st...
Gravitating cosmic strings with flat directions
Hartmann, Betti; Lopez-Eiguren, Asier; Sousa, Kepa; Urrestilla, Jon
2012-01-01
We study field theoretical models for cosmic strings with flat directions in curved space-time. More precisely, we consider minimal models with semilocal, axionic and tachyonic strings, respectively. In flat space-time, the string solutions of these models have a flat direction, i.e., a uniparametric family of configurations with the same energy exists which is associated to a zero mode. We prove that the zero mode survives coupling to gravity, and study the role of the flat direction when co...
Searching for Cosmic Strings in the Cosmic Microwave Background:
Wu, Jiun-Huei Proty
The role of cosmic defects in cosmology is entering its new phase—as a test for several fundamental physics, including unification theories and inflation. We discuss how to use the Cosmic Microwave Background (CMB) to detect cosmic strings, a type of cosmic defects, and how to use this result to constrain the underlying physics. In particular, we use the simulations for the Array for Microwave Background Anisotropy (AMiBA) to demonstrate the power of this approach. The required resolution and sensitivity in such a method are discussed, and so is the possible scientific impact.
Collisions of Cosmic F- and D-strings
Jackson, Mark G.; Jones, Nicholas T.; Polchinski, Joseph
2004-01-01
Recent work suggests that fundamental and Dirichlet strings, and their (p,q) bound states, may be observed as cosmic strings. The evolution of cosmic string networks, and therefore their observational signals, depends on what happens when two strings collide. We study this in string perturbation theory for collisions between all possible pairs of strings; different cases involve sphere, disk, and annulus amplitudes. The result also depends on the details of compactification; the dependence on...
Gravitational Particle Production in Spinning Cosmic String Spacetimes
De Lorenci, V. A.; De Paola, R.; Svaiter, N. F.
1997-01-01
The spontaneous loss of angular momentum of a spinning cosmic string due to particle emission is discussed. The rate of particle production between two assymptotic spacetimes: the spinning cosmic string spacetime in the infinite past and a non-spinning cosmic string spacetime in the infinite future is calculated.
Small scale structure on cosmic strings
International Nuclear Information System (INIS)
I discuss our current understanding of cosmic string evolution, and focus on the question of small scale structure on strings, where most of the disagreements lie. I present a physical picture designed to put the role of the small scale structure into more intuitive terms. In this picture one can see how the small scale structure can feed back in a major way on the overall scaling solution. I also argue that it is easy for small scale numerical errors to feed back in just such a way. The intuitive discussion presented here may form the basis for an analytic treatment of the small structure, which I argue in any case would be extremely valuable in filling the gaps in our resent understanding of cosmic string evolution. 24 refs., 8 figs
Time evolution of a warped cosmic string
Slagter, Reinoud Jan
2014-06-01
The time evolution of a self-gravitating U(1) cosmic string on a warped five-dimensional (5D) axially symmetric spacetime is numerically investigated. Although cosmic strings are theoretically predicted in four-dimensional (4D) general relativistic models, there is still no observational evidence of their existence. From recent observations of the cosmic microwave background (CMB), it is concluded that these cosmic strings cannot provide a satisfactory explanation for the bulk of density perturbations. They even could not survive inflation. It is conjectured that only in a 5D warped braneworld model there will be observable imprint of these so-called cosmic superstrings on the induced effective 4D brane metric for values of the symmetry breaking scale larger than the grand unified theory (GUT) values. The warp factor makes these strings consistent with the predicted mass per unit length on the brane. However, in a time-dependent setting, it seems that there is a wavelike energy-momentum transfer to infinity on the brane, a high-energy braneworld behavior. This in contrast to earlier results in approximation models. Evidence of this information from the bulk geometry could be found in the gravitational cosmic background radiation via gravitational wave energy-momentum affecting the brane evolution. Fluctuations of the brane when there is a U(1) gauge field present, are comparable with the proposed brane tension fluctuations, or branons, whose relic abundance can be a dark matter candidate. We briefly made a connection with the critical behavior at the threshold of black hole formation found by Choptuik several decades ago in self-gravitating time-dependent scalar field models. The critical distinction between dispersion of the scalar waves and singular behavior fade away when a time-dependent warp factor is present.
The Hubble Web: The Dark Matter Problem and Cosmic Strings
Alexander, Stephon
2007-01-01
I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptical galaxies leading to the observed flatness of rotation curves and the Tully-Fisher relation. We find a relationship between the rotatio...
The minimal SUSY B - L model: simultaneous Wilson lines and string thresholds
Deen, Rehan; Ovrut, Burt A.; Purves, Austin
2016-07-01
In previous work, we presented a statistical scan over the soft supersymmetry breaking parameters of the minimal SUSY B - L model. For specificity of calculation, unification of the gauge parameters was enforced by allowing the two Z_3× Z_3 Wilson lines to have mass scales separated by approximately an order of magnitude. This introduced an additional "left-right" sector below the unification scale. In this paper, for three important reasons, we modify our previous analysis by demanding that the mass scales of the two Wilson lines be simultaneous and equal to an "average unification" mass . The present analysis is 1) more "natural" than the previous calculations, which were only valid in a very specific region of the Calabi-Yau moduli space, 2) the theory is conceptually simpler in that the left-right sector has been removed and 3) in the present analysis the lack of gauge unification is due to threshold effects — particularly heavy string thresholds, which we calculate statistically in detail. As in our previous work, the theory is renormalization group evolved from to the electroweak scale — being subjected, sequentially, to the requirement of radiative B - L and electroweak symmetry breaking, the present experimental lower bounds on the B - L vector boson and sparticle masses, as well as the lightest neutral Higgs mass of ˜125 GeV. The subspace of soft supersymmetry breaking masses that satisfies all such constraints is presented and shown to be substantial.
Superconducting cosmic string evolution of quasars
International Nuclear Information System (INIS)
The quasars may have been undergoing two evolutionary processes after they formed. As a result of the string loops shrinking at the first stage, the luminosities of the quasars increased gradually up to their maximum value at the redshift z ∼ 2, after then the second evolutionary stage began and the luminosity reduced. This result can be fitted by luminosity counting of quasars. Observable limit of quasars can be obtained naturally. Many phenomena, such as radiomorphology, density distribution between fuzz structure and broad line region and rotational curve may also originate from the first evolutionary stage of quasars as cosmic string. (author). 10 refs
Scattering of cosmic strings by black holes: loop formation
Dubath, Florian; Sakellariadou, Mairi; Viallet, Claude
2007-01-01
We study the deformation of a long cosmic string by a nearby rotating black hole. We examine whether the deformation of a cosmic string, induced by the gravitational field of a Kerr black hole, may lead to the formation of a loop of cosmic string. The segment of the string which enters the ergosphere of a rotating black hole gets deformed and, if it is sufficiently twisted, it can self-intersect chopping off a loop of cosmic string. We find that the formation of a loop, via this mechanism, is...
Cosmic strings and baryon decay catalysis
Energy Technology Data Exchange (ETDEWEB)
Gregory, R.; Perkins, W.B.; Davis, A.C.; Brandenberger, R.H. (Fermi National Accelerator Lab., Batavia, IL (USA); Cambridge Univ. (UK); Brown Univ., Providence, RI (USA). Dept. of Physics)
1989-09-01
Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. We review the catalysis processes both in the free quark and skyrmion pictures and discuss the implications for baryogenesis. We present a computation of the cross section for monopole catalyzed skyrmion decay using classical physics. We also discuss some effects which can screen catalysis processes. 32 refs., 1 fig.
Constraints on brane inflation and cosmic strings
International Nuclear Information System (INIS)
By considering simple, but representative, models of brane inflation from a single brane–antibrane pair in the slow roll regime, we provide constraints on the parameters of the theory imposed by measurements of the cosmic microwave background (CMB) anisotropies by WMAP (Wilkinson Microwave Anisotropy Probe) including a cosmic string component. We find that inclusion of the string component is critical in constraining parameters. In the most general model studied, which includes an inflaton mass term, as well as the brane–antibrane attraction, values nsP at horizon exit. We also investigate models with a mass term. These observational considerations suggest that such models have r−5, which can only be circumvented in the fast roll regime, or by increasing the number of antibranes. Such a value of r would not be detectable in any CMB polarization experiment likely in the near future, but the B-mode signal from the cosmic strings could be detectable. We present forecasts of what a similar analysis using PLANCK data would yield and find that it should be possible to rule out Gμ>6.5 × 10−8 using just the TT, TE and EE power spectra
Gravitational Field and Equations of Motion of Nonlinear Cosmic String
Chechin, L M
1999-01-01
For the case of tension tensor containing nonlinear terms in $l^{\\alpha}$, we give generalization of Vilenkin metrics and equations of motion of cosmic string. Dynamics of nonlinear string in (1+1)-dimensional universe is discussed.
Limits on Black Hole Formation from Cosmic String Loops
MacGibbon, Jane H.; Brandenberger, Robert H.; Wichoski, U. F.
1997-01-01
In theories with cosmic strings, a small fraction of string loops may collapse to form black holes. In this Letter, various constraints on such models involving black holes are considered. Hawking radiation from black holes, gamma and cosmic ray flux limits and constraints from the possible formation of stable black hole remnants are reanalyzed. The constraints which emerge from these considerations are remarkably close to those derived from the normalization of the cosmic string model to the...
From spinning to non-spinning cosmic string spacetimes
De Lorenci, V. A.; De Paola, R. D. M.; Svaiter, N. F.
1999-01-01
We analyse the properties of a fluid generating a spinning cosmic string spacetime with flat limiting cases corresponding to a constant angular momentum in the infinite past and static configuration in the infinite future. The spontaneous loss of angular momentum of a spinning cosmic string due to particle emission is discussed. The rate of particle production between the spinning and non-spinning cosmic string spacetimes is calculated.
Warped Angle-deficit of a 5 Dimensional Cosmic String
Slagter, Reinoud Jan; Masselink, Derk
2011-01-01
We present a cosmic string on a warped five dimensional space time in Einstein-Yang-Mills theory. Four-dimensional cosmic strings show some serious problems concerning the mechanism of string smoothing related to the string mass per unit length, $G\\mu \\approx 10^{-6}$. A warped cosmic string could overcome this problem and also the superstring requirement that $G\\mu$ must be of order 1, which is far above observational bounds. Also the absence of observational evidence of axially symmetric le...
The Hubble Web: The Dark Matter Problem and Cosmic Strings
International Nuclear Information System (INIS)
I propose a reinterpretation of cosmic dark matter in which a rigid network of cosmic strings formed at the end of inflation. The cosmic strings fulfill three functions: At recombination they provide an accretion mechanism for virializing baryonic and warm dark matter into disks. These cosmic strings survive as configurations which thread spiral and elliptical galaxies leading to the observed flatness of rotation curves and the Tully-Fisher relation. We find a relationship between the rotational velocity of the galaxy and the string tension and discuss the testability of this model.
Stable and Metastable Cosmic Strings in Heterotic M-Theory
Buchbinder, Evgeny I.
2006-01-01
We address the question of finding stable and metastable cosmic strings in quasi-realistic heterotic M-theory compactifications with stabilized moduli. According to Polchinski's conjecture, the only stable strings in the absence of massless fields are Aharonov-Bohm strings. Such strings could potentially be created in heterotic compactifications as bound states of open membranes, five-branes wrapped on four-cycles and solitonic strings. However, in generic compactifications, the process of mo...
Thin shells joining local cosmic string geometries
Eiroa, Ernesto F; Simeone, Claudio
2016-01-01
In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a standard thin shell and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters.
Dirac Born Infeld (DBI) Cosmic Strings
Babichev, Eugeny; Brax, Philippe; Caprini, Chiara; Martin, Jerome; Steer, Daniele
2008-01-01
Motivated by brane physics, we consider the non-linear Dirac-Born-Infeld (DBI) extension of the Abelian-Higgs model and study the corresponding cosmic string configurations. The model is defined by a potential term, assumed to be of the mexican hat form, and a DBI action for the kinetic terms. We show that it is a continuous deformation of the Abelian-Higgs model, with a single deformation parameter depending on a dimensionless combination of the scalar coupling constant, the vacuum expectati...
Geodesic Lines in the Gravitational Field of Nonlinear Cosmic Strings
Chechin, L M
2000-01-01
We briefly review the equations of motion and the space-time interval due to the nonlinear cosmic string that have been derived in ref. [3] for the first time. The different types of isotropic and nonisotropic geodesic lines in the gravitational field of nonlinear cosmic string have been analyzed in detail.
The 21 cm signature of cosmic string wakes
International Nuclear Information System (INIS)
We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are in optical galaxy surveys. We find that, provided the tension of the cosmic string exceeds a critical value (which depends on both the redshift when the string wake is created and the redshift of observation), a cosmic string wake will generate an emission signal with a brightness temperature which approaches a limiting value which at a redshift of z+1 = 30 is close to 400 mK in the limit of large string tension. The signal will have a specific signature in position space: the excess 21cm radiation will be confined to a wedge-shaped region whose tip corresponds to the position of the string, whose planar dimensions are set by the planar dimensions of the string wake, and whose thickness (in redshift direction) depends on the string tension. For wakes created at zi+1 = 103, then at a redshift of z+1 = 30 the critical value of the string tension μ is Gμ = 6 × 10−7, and it decreases linearly with redshift (for wakes created at the time of equal matter and radiation, the critical value is a factor of two lower at the same redshift). For smaller tensions, cosmic strings lead to an observable absorption signal with the same wedge geometry
Pair production of black holes on cosmic strings
Hawking, Stephen William; Ross, Simon F
1995-01-01
We discuss the pair creation of black holes by the breaking of a cosmic string. We obtain an instanton describing this process from the C metric, and calculate its probability. Only topologically unstable strings can break, as topologically stable strings cannot have ends.
Limits on black hole formation from cosmic string loops
International Nuclear Information System (INIS)
In theories with cosmic strings, a small fraction of string loops may collapse to form black holes. In this paper, various constraints on such models involving black holes are considered. Hawking radiation from black holes, gamma and cosmic ray flux limits and constraints from the possible formation of stable black hole remnants are reanalyzed. The constraints which emerge from these considerations are remarkably close to those derived from the normalization of the cosmic string model to the cosmic microwave background anisotropies. copyright 1998 The American Physical Society
Pair creation of black holes joined by cosmic strings
Emparan García de Salazar, Roberto A.
1995-01-01
We argue that production of charged black hole pairs joined by a cosmic string in the presence of a magnetic field can be analyzed using the Ernst metric. The effect of the cosmic string is to pull the black holes towards each other, opposing to the background field. An estimation of the production rate using the Euclidean action shows that the process is suppressed as compared to the formation of black holes without strings.
The Minimal SUSY $B-L$ Model: Simultaneous Wilson Lines and String Thresholds
Deen, Rehan; Purves, Austin
2016-01-01
In previous work, we presented a statistical scan over the soft supersymmetry breaking parameters of the minimal SUSY $B-L$ model. For specificity of calculation, unification of the gauge parameters was enforced by allowing the two ${\\mathbb Z}_{3}\\times {\\mathbb Z}_{3}$ Wilson lines to have mass scales separated by approximately an order of magnitude. This introduced an additional "left-right" sector below the unification scale. In this paper, for three important reasons, we modify our previous analysis by demanding that the mass scales of the two Wilson lines be simultaneous and equal to an "average unification" mass $\\left$. The present analysis is 1) more "natural" than the previous calculations, which were only valid in a very specific region of the Calabi-Yau moduli space, 2) the theory is conceptually simpler in that the left-right sector has been removed and 3) in the present analysis the lack of gauge unification is due to threshold effects--particularly heavy string thresholds, which we calculate st...
Fermionic vacuum polarization in compactified cosmic string spacetime
Energy Technology Data Exchange (ETDEWEB)
Bellucci, S. [INFN, Laboratori Nazionali di Frascati, Frascati (Italy); Bezerra de Mello, E.R.; Padua, A. de [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Saharian, A.A. [Yerevan State University, Department of Physics, Yerevan (Armenia)
2014-01-15
We investigate the fermionic condensate and the vacuum expectation value (VEV) of the energy-momentum tensor for a charged massive fermionic field in the geometry of a cosmic string compactified along its axis. In addition, we assume the presence of two types of magnetic fluxes: a flux running along the cosmic string and another enclosed by the compact dimension. These fluxes give rise to Aharanov-Bohm-like effects on the VEVs. The VEVs are decomposed into two parts corresponding to the geometry of a straight cosmic string without compactification plus a topological part induced by the compactification of the string axis. Both contributions are even periodic functions of the magnetic fluxes with period equal to the flux quantum. The vacuum energy density is equal to the radial stress for the parts corresponding to the straight cosmic string and the topological one. Moreover, the axial stress is equal to the energy density for the parts corresponding to the straight cosmic string; however, for massive fermionic fields this does not occur for the topological contributions. With respect to the dependence on the magnetic fluxes, both the fermionic condensate and the vacuum energy density, can be either positive or negative. Moreover, for points near the string, the main contribution to the VEVs comes from the straight cosmic string part, whereas at large distances the topological ones dominate. In addition to the local characteristics of the vacuum state, we also evaluate the part in the topological Casimir energy induced by the string. (orig.)
Fermionic vacuum polarization in compactified cosmic string spacetime
International Nuclear Information System (INIS)
We investigate the fermionic condensate and the vacuum expectation value (VEV) of the energy-momentum tensor for a charged massive fermionic field in the geometry of a cosmic string compactified along its axis. In addition, we assume the presence of two types of magnetic fluxes: a flux running along the cosmic string and another enclosed by the compact dimension. These fluxes give rise to Aharanov-Bohm-like effects on the VEVs. The VEVs are decomposed into two parts corresponding to the geometry of a straight cosmic string without compactification plus a topological part induced by the compactification of the string axis. Both contributions are even periodic functions of the magnetic fluxes with period equal to the flux quantum. The vacuum energy density is equal to the radial stress for the parts corresponding to the straight cosmic string and the topological one. Moreover, the axial stress is equal to the energy density for the parts corresponding to the straight cosmic string; however, for massive fermionic fields this does not occur for the topological contributions. With respect to the dependence on the magnetic fluxes, both the fermionic condensate and the vacuum energy density, can be either positive or negative. Moreover, for points near the string, the main contribution to the VEVs comes from the straight cosmic string part, whereas at large distances the topological ones dominate. In addition to the local characteristics of the vacuum state, we also evaluate the part in the topological Casimir energy induced by the string. (orig.)
The bispectrum of cosmic string temperature fluctuations including recombination effects
Regan, Donough
2015-01-01
We calculate the cosmic microwave background temperature bispectrum from cosmic strings, for the first time including the contributions from the last scattering surface, using a well-established Gaussian model for the string energy-momentum correlation functions, and a simplified model for the cosmic fluid. We check our approximation for the integrated Sachs-Wolfe (ISW) contribution against the bispectrum obtained from the full sky map of the cosmic string ISW signal used by the Planck team, obtaining good agreement. We validate our model for the last scattering surface contribution by comparing the predicted temperature power spectrum with that obtained from a full Boltzmann code treatment applied to the Unconnected Segment Model of a string network. We find that including the last scattering contribution has only a small impact on the upper limit on the string tension resulting from the bispectrum at Planck resolutions, and argue that the bispectrum is unlikely to be competitive with the power spectrum at a...
Cosmic strings in hidden sectors: 2. Cosmological and astrophysical signatures
International Nuclear Information System (INIS)
Cosmic strings can arise in hidden sector models with a spontaneously broken Abelian symmetry group. We have studied the couplings of the Standard Model fields to these so-called dark strings in the companion paper. Here we survey the cosmological and astrophysical observables that could be associated with the presence of dark strings in our universe with an emphasis on low-scale models, perhaps TeV. Specifically, we consider constraints from nucleosynthesis and CMB spectral distortions, and we calculate the predicted fluxes of diffuse gamma ray cascade photons and cosmic rays. For strings as light as TeV, we find that the predicted level of these signatures is well below the sensitivity of the current experiments, and therefore low scale cosmic strings in hidden sectors remain unconstrained. Heavier strings with a mass scale in the range 1013 GeV to 1015 GeV are at tension with nucleosynthesis constraints
Cosmic Strings in Hidden Sectors: 2. Cosmological and Astrophysical Signatures
Long, Andrew J
2014-01-01
Cosmic strings can arise in hidden sector models with a spontaneously broken Abelian symmetry group. We have studied the couplings of the Standard Model fields to these so-called dark strings in the companion paper. Here we survey the cosmological and astrophysical observables that could be associated with the presence of dark strings in our universe with an emphasis on low-scale models, perhaps TeV. Specifically, we consider constraints from nucleosynthesis and CMB spectral distortions, and we calculate the predicted fluxes of diffuse gamma ray cascade photons and cosmic rays. For strings as light as TeV, we find that the predicted level of these signatures is well below the sensitivity of the current experiments, and therefore low scale cosmic strings in hidden sectors remain unconstrained. Heavier strings with a mass scale in the range 10^(13) GeV to 10^(15) GeV are at tension with nucleosynthesis constraints.
Gravitating non-Abelian cosmic strings
Santo, Antônio de Padua
2015-01-01
In this paper we study regular cosmic string solutions of the non-Abelian Higgs model coupled with the Einstein gravity. In order to do that, we constructed a set of coupled differential ordinary equation. Because there is no closed solution for this set of equations, we solve it numerically. The solutions that we are interested in asymptote to a flat space-time with a planar angle deficit. This model under consideration present two bosonic sectors, besides the non-Abelian gauge one, coupled minimally with the gravitational fields. The two bosonic sectors may present a direct coupling, which plays an important role on the behavior of the matter and gauge fields and also on the behavior on the geometry of the spacetime. We explicitly analyze the behaviors of the energy density and planar angle deficit as function of the energy scale where the gauge symmetry is spontaneously broken and the coupling interaction between the bosonic sectors.
Relativistic Landau Levels in the Rotating Cosmic String Spacetime
Cunha, M S; Christiansen, H R; Bezerra, V B
2016-01-01
We calculate the energy levels of a spinless massive and charged particle interacting with a stationary rotating cosmic string in a region with a static homogeneous magnetic field parallel to the string. First, we completely solve the Klein-Gordon equation in that particular spacetime, checking consistency in the non-relativistic limit and comparing with the static string case. We also solve the problem for a magnetized rotating cosmic string in order to find the Landau levels using rigid-wall boundary conditions, and discuss the possibility of these levels to be purely induced by spacetime rotation.
Cosmic D--term Strings as Wrapped D3 Branes
Halyo, E
2004-01-01
We describe cosmic D--term strings as D3 branes wrapped on a resolved conifold. The matter content that gives rise to D--term strings is shown to describe the world--volume theory of a space--filling D3 brane transverse to the conifold which itself is a wrapped D5 brane. We show that, in this brane theory, the tension of the wrapped D3 brane mathces that of the D--term string. We argue that there is a new type of cosmic string which arises from fractional D1 branes on the world--volume of a fractional D3 brane.
Adiabatic fluctuations from cosmic strings in a contracting universe
International Nuclear Information System (INIS)
We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today
Cosmic D-strings as Axionic D-term Strings
Blanco-Pillado, Jose J.; Dvali, Gia; Redi, Michele(INFN — Sezione di Firenze, Via G. Sansone, 1, I-50019, Sesto Fiorentino, Italy)
2005-01-01
In this work we derive non-singular BPS string solutions from an action that captures the essential features of a D-brane-anti-D-brane system compactified to four dimensions. The model we consider is a supersymmetric abelian Higgs model with a D-term potential coupled to an axion-dilaton multiplet. The strings in question are axionic D-term strings which we identify with the D-strings of type II string theory. In this picture the Higgs field represents the open string tachyon of the D-Dbar pa...
Intercommutation of U(1) global cosmic strings
Moore, Guy D.
2016-01-01
Global strings (those which couple to Goldstone modes) may play a role in cosmology. In particular, if the QCD axion exists, axionic strings may control the efficiency of axionic dark matter abundance. The string network dynamics depend on the string intercommutation efficiency (whether strings re-connect when they cross). We point out that the velocity and angle in a collision between global strings "renormalize" between the network scale and the microscopic scale, and that this plays a sign...
Aharonov-Bohm effect in curved space and cosmic strings
International Nuclear Information System (INIS)
The paper deals with the development of the theory of nonrelativistic particle scattering in the cosmic string field, which is considered as a registration of magnetic and gravitation strings. The effects, which are caused by the finite nature of the transverse parameters of the strings, are taken into account making sufficiently general assumptions about the distribution of the magnetic field and space curvature inside the string. It is shown that in a certain region of angles the differential scattering section significantly depends on the string magnetic flux value at all absolute values of the bombarding particle wind vector. 34 refs
Coupled field solutions for U(1)-gauge cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Laguna-Castillo, P.; Matzner, R.A.
1987-12-15
Numerical solutions for the coupled Einstein-scalar-gauge field equations of a static, infinitely long, straight, U(1)-gauge cosmic string are obtained. The boundary conditions at the axis of the string and at radial infinity are chosen such that the solutions represent an isolated string; that is, the metric fields of the string approach Minkowski spacetime minus a wedge at radial infinity. The numerical solutions for the metric, scalar, and gauge fields, and for the components of the energy-momentum tensor, are classified according to the energy scale of symmetry breaking and the mass ratio of the scalar and gauge fields of the strings.
Tackling tangledness of cosmic strings by knot polynomial topological invariants
Li, Xinfei; Huang, Yong-Chang
2016-01-01
Cosmic strings in the early universe have received revived interest in recent years. In this paper we derive these structures as topological defects from singular distributions of the quintessence field of dark energy. Our emphasis is placed on the topological charge of tangled cosmic strings, which originates from the Hopf mapping and is a Chern-Simons action possessing strong inherent tie to knot topology. It is shown that the Kauffman bracket knot polynomial can be constructed in terms of this charge for un-oriented knotted strings, serving as a topological invariant much stronger than the traditional Gauss linking numbers in characterizing string topology. Especially, we introduce a mathematical approach of breaking-reconnection which provides a promising candidate for studying physical reconnection processes within the complexity-reducing cascades of tangled cosmic strings.
Physical cosmic strings do not generate closed timelike curves
International Nuclear Information System (INIS)
We reexamine the causal properties of geometries generated by parallel, moving cosmic strings, particularly our statement that closed timelike curves are forbidden there. Contrary to a recent claim, such acausal behavior cannot be realized by physical, timelike, sources
Probabilistic estimates of the number of cosmic strings
International Nuclear Information System (INIS)
The dependences of the mean expected number of cosmic strings on their redshift up to the surface of last scattering have been derived. The calculations are based on the geometric probability of a straight string segment crossing a given field and on information about the absence of strings when they are searched for via their gravitational lensing effects in optical catalogs. It is shown that there are no strings for redshifts 0 3 at the 95% confidence level. The expected number of strings for redshifts up to z = 1100 can be no more than 2.4 × 104 at the 95% confidence level. The latter estimate is sensitive to a priori information about the absence of cosmic strings in the redshift range 0 < z < 1.954 in a field of 4.48 square degrees in optical catalogs; it is smaller than the estimate without allowance for this information by 6%.
The stability of D-term cosmic strings
International Nuclear Information System (INIS)
In this article, we discuss the semi-classical stability of the D-term string solution of D=4, N=1 supergravity with a constant Fayet-Iliopoulos term. Regardless of the particular theory one is interested in, the stability of cosmic strings is necessary if we hope to observe them. We apply the spinorial Witten-Nester method to prove a positive energy theorem for the D-term cosmic string background with positive deficit angle. We also pay particular attention to the negative deficit angle D-term string, which is known to violate the dominant energy condition. Within the class of string solutions we consider, this violation implies that the negative deficit angle D-term string must have a naked pathology and therefore the positive energy theorem we prove does not apply to it. (orig.)
Pair Production of Black Holes on Cosmic Strings
Hawking, S. W.; Ross, Simon F.
1995-11-01
We discuss the pair creation of black holes by the breaking of a cosmic string. We obtain an instanton describing this process from the C metric, and calculate its probability. This is very low for the strings that have been suggested for galaxy formation.
Perturbations from cosmic strings in cold dark matter
Albrecht, Andreas; Stebbins, Albert
1992-01-01
A systematic linear analysis of the perturbations induced by cosmic strings in cold dark matter is presented. The power spectrum is calculated and it is found that the strings produce a great deal of power on small scales. It is shown that the perturbations on interesting scales are the result of many uncorrelated string motions, which indicates a much more Gaussian distribution than was previously supposed.
General Relativity, Scalar Fields and Cosmic Strings.
Burd, Adrian Benedict
1987-09-01
in the Appendix. Most of the models exhibit power-law inflation and we examine the limits on the potential imposed by the constraints on the inflationary period. The last section of the thesis involves a review of the cosmic string picture of galaxy formation. We examine the structure of the string from the viewpoint of the fields. We conjecture that the solutions are stable against small time-dependent perturbations and minimise the energy. We extend this analysis to straight strings in expanding space -times and find that at late times the fields settle down to a steady solution. At early times the fields oscillate and the stress-tensor of the fields is non-diagonal. The oscillations are probably not important since they die away rapidly but the form of the stress-tensor may have to be taken into account when considering the back reaction of the string on the space-time shortly after the string is formed.
Evidence for a scaling solution in cosmic-string evolution
Bennett, David P.; Bouchet, Francois R.
1988-01-01
Numerical simulations are used to study the most fundamental issue of cosmic-string evolution: the existence of a scaling solution. Strong evidence is found that a scaling solution does indeed exist. This justifies the main assumption on which the cosmic-string theories of galaxy formation is based. The main conclusion coincides with that of Albrecht and Turok (1985) but the results are not consistent with theirs. In fact, the results indicate that the details of string evolution are very different from the standard dogma.
Non-Thermal Dark Matter from Cosmic Strings
Cui, Yanou; David E. Morrissey
2008-01-01
Cosmic strings can be created in the early universe during symmetry-breaking phase transitions, such as might arise if the gauge structure of the standard model is extended by additional U(1) factors at high energies. Cosmic strings present in the early universe form a network of long horizon-length segments, as well as a population of closed string loops. The closed loops are unstable against decay, and can be a source of non-thermal particle production. In this work we compute the density o...
Search for Cosmic Strings in the COSMOS Survey
Christiansen, J L; Goldman, J; Teng, I P W; Foley, M; Smoot, G F
2010-01-01
We search the COSMOS survey for pairs of galaxies consistent with the gravitational lensing signature of a cosmic string. The COSMOS survey imaged 1.64 square degrees using the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope (HST). Our technique includes estimates of the efficiency for finding the lensed galaxy pair. We find no evidence for cosmic strings with a mass per unit length of G\\mu/c^2 < 3.0E-7 out to redshifts greater than 0.6 at 95% confidence. This corresponds to a global limit on Omega_string<0.0017.
Numerical study of cosmic censorship in string theory
International Nuclear Information System (INIS)
Recently Hertog, Horowitz, and Maeda have argued that cosmic censorship can be generically violated in string theory in anti-de Sitter spacetime by considering a collapsing bubble of a scalar field whose mass saturates the Breitenlohner-Freedman bound. We study this system numerically, and find that black holes form rather than naked singularities, implying that cosmic censorship is upheld. (author)
Numerical study of cosmic censorship in string theory
Energy Technology Data Exchange (ETDEWEB)
Gutperle, Michael E-mail: gutperle@physics.ucla.edu; Kraus, Per
2004-04-01
Recently Hertog, Horowitz, and Maeda have argued that cosmic censorship can be generically violated in string theory in anti-de Sitter spacetime by considering a collapsing bubble of a scalar field whose mass saturates the Breitenlohner-Freedman bound. We study this system numerically, and find that black holes form rather than naked singularities, implying that cosmic censorship is upheld. (author)
Vacuum polarization by a flat boundary in cosmic string spacetime
International Nuclear Information System (INIS)
In this paper, we analyze the vacuum expectation values of the field squared and the energy-momentum tensor associated with a massive scalar field in a higher dimensional cosmic string spacetime, obeying Dirichlet or Neumann boundary conditions on the surface orthogonal to the string. In order to develop this analysis, the corresponding Green's function is obtained. The Green's function is given by the sum of two expressions: the first one corresponds to the standard Green's function in the boundary-free cosmic string spacetime and the second contribution is induced by the boundary. The boundary-induced parts have opposite signs for Dirichlet and Neumann scalars. Because the analysis of vacuum polarization effects in the boundary-free cosmic string spacetime has been developed in the literature, here we are mainly interested in the calculations of the effects induced by the boundary. In this way closed expressions for the corresponding expectation values are provided, as well as their asymptotic behavior in different limiting regions being investigated. We show that the non-trivial topology due to the cosmic string enhances the boundary-induced vacuum polarization effects for both the field squared and the energy-momentum tensor, compared to the case of a boundary in Minkowski spacetime. The presence of the cosmic string induces non-zero stress along the direction normal to the boundary. The corresponding vacuum force acting on the boundary is investigated.
Exceptional Colloquium: The Rise, Fall, and Rebirth of Cosmic Strings
CERN. Geneva
2005-01-01
In the 1980s many people were excited by the concept that cosmic strings, as relics of the Grand Unified Era, could be responsible for the formation of cosmic structure. In the 1990s the cosmic string concept steadily lost ground to the Inflationary model both as a result of the difficulty of calculations and more definitively through observations of the CMB. About the time many expected the new WMAP data to deliver the coup de grace, the concepts of cosmic strings as major physical phenomena (not so important in structure formation) has begun a renaissance. This new interest is motivated by one of the original ideas that topological defects are inevitable in symmetry breaking by the Kibble (1976) mechanism and the introduction of new ideas such as brane-cosmology/inflation and the realization that cosmic strings may be the only acceptable such defect. We find ourselves back in the business of trying to detect or limit and understand cosmic strings once again for the insight and constraints they put on p...
Fermion Energies in the Background of a Cosmic String
Graham, N; Weigel, H
2011-01-01
We provide a thorough exposition, including technical and numerical details, of previously published results on the quantum stabilization of cosmic strings. Stabilization occurs through the coupling to a heavy fermion doublet in a reduced version of the standard model. We combine the vacuum polarization energy of fermion zero-point fluctuations and the binding energy of occupied energy levels, which are of the same order in a semi-classical expansion. Populating these bound states assigns a charge to the string. We show that strings carrying fermion charge become stable if the electro-weak bosons are coupled to a fermion that is less than twice as heavy as the top quark. The vacuum remains stable in our model, because neutral strings are not energetically favored. These findings suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model.
Cosmic strings in a product Abelian gauge field theory
International Nuclear Information System (INIS)
It is shown that multiply distributed cosmic strings arise in the product Abelian gauge field theory of Tong and Wong where vortices generated from an extra gauge sector are used to realize magnetic impurities. It is seen that, in view of the fully coupled Einstein and gauge-matter equations, the presence of such cosmic strings in the form of topological defects is essential for gravitation. Asymptotic behavior of the string solutions can be precisely described to allow the derivation of a necessary and sufficient condition for the gravitational metric to be geodesically complete and an explicit calculation of the deficit angle proportional to the string tension, both stated in terms of string numbers, energy levels of broken symmetries, and the universal gravitational constant
Interaction of U(1) cosmic strings: Numerical intercommutation
Energy Technology Data Exchange (ETDEWEB)
Matzner, R.A.
1988-09-01
The putative ability of cosmic strings to act as seeds for galaxies depends on the efficiency of a number of processes that produce an initial network of strings and then allow them to evolve to a population that can act as condensation centers. Here the classical field theory of the interaction of cosmic strings is studied. A limited survey of numerical evolutions has been carried out. Calculations have been carried out showing parallel string--string repulsion; string--antistring (i.e., antiparallel string) annihilation with initial velocity v = 0 and v = 0.75; string--string collision at right angles with v/c = 0.1, 0.5, 0.75, 0.85, 0.9c, with v/c = 0.75 at theta = ..pi../4 and at theta = 3..pi../4, and with v/c = 0.9 at theta = 7..pi../8; and string--string and string--antistring collisions with v/c = 0.9 and v/c = 0.95. Intercommutation occurs in all situations so far investigated except that string--antistring collision with v/capprox. >0.90 apparently leads to reemergence, i.e., no intercommutation. All simulations have a ''sombrero'' potential V (phi) = lambda(chemically bondphichemically bond/sup 2/-sigma/sup 2/)/sup 2/ and a gauge field coupling e. (The numerical results are obtained with lambda = 0.01, e = 0.2, giving the gauge field a slightly longer scale length than that of the scalar field.)
Effects of the image universe on cosmic strings
International Nuclear Information System (INIS)
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.)
Observational constraints on the types of cosmic strings
International Nuclear Information System (INIS)
This paper is aimed at setting observational limits to the number of cosmic strings (Nambu-Goto, Abelian-Higgs, semilocal) and other topological defects (textures). Radio maps of CMB anisotropy, provided by the space mission Planck for various frequencies, were filtered and then processed by the method of convolution with modified Haar functions (MHF) to search for cosmic string candidates. This method was designed to search for solitary strings, without additional assumptions as regards the presence of networks of such objects. The sensitivity of the MHF method is δT ∼ 10 μK in a background of δT ∼ 100 μK. The comparison of these with previously known results on search string network shows that strings can only be semilocal in the range of 1 / 5, with the upper restriction on individual string tension (linear density) of Gμ/c2 ≤ 7.36 x 10-7. The texture model is also legal. There are no strings with Gμ/c2 > 7.36 x 10-7. However, a comparison with the data for the search of non-Gaussian signals shows that the presence of several (up to three) Nambu-Goto strings is also possible. For Gμ/c2 ≤ 4.83 x 10-7 the MHF method is ineffective because of unverifiable spurious string candidates. Thus the existence of strings with tensions Gμ/c2 ≤ 4.83 x 10-7 is not prohibited but it is beyond the Planck data possibilities. The same string candidates have been found in the WMAP 9-year data. Independence of Planck and WMAP data sets serves as an additional argument to consider those string candidates as very promising. However, the final proof should be given by optical deep surveys. (orig.)
The String and the Cosmic Bounce
Bozza V.
2014-01-01
String theory introduces a new fundamental scale (the string length) that is expected to regularize the singularities of classical general relativity. In a cosmological context, the Big Bang is no longer regarded as the beginning of time, but just a transition between a Pre-Big Bang collapse phase and the current expansion. We will review old and recent attempts to build consistent bouncing cosmologies inspired to string theories, discussing their solved and unsolved problems, focussing on th...
International Nuclear Information System (INIS)
In this paper we study the footprint of cosmic string as the topological defects in the very early universe on the cosmic microwave background radiation. We develop the method of level crossing analysis in the context of the well-known Kaiser-Stebbins phenomenon for exploring the signature of cosmic strings. We simulate a Gaussian map by using the best fit parameter given by WMAP-7 and then superimpose cosmic strings effects on it as an incoherent and active fluctuations. In order to investigate the capability of our method to detect the cosmic strings for the various values of tension, Gμ, a simulated pure Gaussian map is compared with that of including cosmic strings. Based on the level crossing analysis, the superimposed cosmic string with Gμ∼>4 × 10−9 in the simulated map without instrumental noise and the resolution R = 1' could be detected. In the presence of anticipated instrumental noise the lower bound increases just up to Gμ∼>5.8 × 10−9
Evolution of a non-Abelian cosmic string network
International Nuclear Information System (INIS)
We describe a numerical simulation of the evolution of an S3 cosmic string network which takes fully into account the noncommutative nature of the cosmic string fluxes and the topological obstructions which hinder strings from moving past each other or intercommuting. The influence of initial conditions, string tensions, and other parameters on the network close-quote s evolution is explored. Contrary to some previous suggestions, we find no strong evidence of the open-quotes freezingclose quotes required for a string-dominated cosmological scenario. Instead, the results in a broad range of regimes are consistent with the familiar scaling law, i.e., a constant number of strings per horizon volume. The size of this number, however, can vary quite a bit, as can other overall features. There is a surprisingly strong dependence on the statistical properties of the initial conditions. We also observe a rich variety of interesting new structures, such as light string webs stretched between heavier strings, which are not seen in Abelian networks. copyright 1998 The American Physical Society
Bosonic structure of realistic SO(10) supersymmetric cosmic strings
Allys, Erwan
2016-05-01
We study the bosonic structure of F -term Nambu-Goto cosmic strings forming in a realistic SO(10) implementation, assuming standard hybrid inflation. We describe the supersymmetric grand unified theory, and its spontaneous symmetry breaking scheme in parallel with the inflationary process. We also write the explicit tensor formulation of its scalar sector, focusing on the subrepresentations singlet under the standard model, which is sufficient to describe the string structure. We then introduce an ansatz for Abelian cosmic strings, discussing in details the hypothesis, and write down the field equations and boundary conditions. Finally, after doing a perturbative study of the model, we present and discuss the results obtained with numerical solutions of the string structure.
Bosonic structure of realistic SO(10) SUSY cosmic strings
Allys, E
2015-01-01
We study the bosonic structure of F-term Nambu-Goto cosmic strings forming in a realistic SO(10) implementation, assuming standard hybrid inflation. We describe the supersymmetric Grand Unified Theory, and its SSB scheme in parallel with the inflationary process. We also write the explicit tensor formulation of its scalar sector, focusing on the sub-representations singlet under the Standard Model, which is sufficient to describe the string structure. We then introduce an ansatz for abelian cosmic strings, discussing in details the hypothesis, and write down the field equations and boundary conditions. Finally, after doing a perturbative study of the model, we present and discuss the results obtained with numerical solutions of the string structure.
Light-Cone Fluctuations in the Cosmic String Spacetime
Mota, H F; Bessa, C H G; Bezerra, V B
2016-01-01
In this paper we consider light-cone fluctuations arising as a consequence of the nontrivial topology of the locally flat cosmic string spacetime. By setting the light-cone along the z-direction we are able to develop a full analysis to calculate the renormalized graviton two-point function, as well as the mean square fluctuation in the geodesic interval function and the time delay (or advance) in the propagation of a light-pulse. We found that all these expressions depend upon the parameter characterizing the conical topology of the cosmic string spacetime and vanish in the absence of it. We also point out that at large distances from the cosmic string the mean square fluctuation in the geodesic interval function is extremely small while in the opposite limit it logarithmically increases, improving the signal and thus, making possible the detection of such quantity.
Cosmic string interactions induced by gauge and scalar fields
Kabat, Daniel; Sarkar, Debajyoti
2012-01-01
We study the interaction between two parallel cosmic strings induced by gauge fields and by scalar fields with non-minimal couplings to curvature. For small deficit angles the gauge field behaves like a collection of non-minimal scalars with a specific value for the non-minimal coupling. We check this equivalence by computing the interaction energy between strings at first order in the deficit angles. This result provides another physical context for the "contact terms" which play an importan...
Radio Jets and Galaxies as Cosmic String Probes
Feng, Fa-bo
2011-01-01
The lensing effect of a cosmic string is studied, and some new methods are proposed to detect the cosmic string. The technique for using jets as extended gravitational lensing probes was firstly explored by Kronberg. We use the "alignment-breaking parameter" $ \\eta_G $ as a sensitive indicator of gravitational distortion by a wiggly cosmic string. Then, we applied the non-constant deflection angle to jets, and $ \\eta_G $ of a specific jet is just related to the projected slope of the jet. At least three jets in the sample of Square Kilometer Array (SKA) would have significant signals ($ \\eta_G >10^\\circ $) if the wiggly infinite cosmic string existed. The distortion of elliptical object is also studied and used to do a statistical research on directions of axes and ellipticities of galaxies. In the direction of the string, we find that galaxies appear to be rounder for an observer and the distribution of apparent ellipticity changes correspondingly. Ellipticity distribution of current SDSS spiral sample has t...
New CMB constraints for Abelian Higgs cosmic strings
Lizarraga, Joanes; Daverio, David; Hindmarsh, Mark; Kunz, Martin
2016-01-01
We present cosmic microwave background (CMB) power spectra from recent numerical simulations of cosmic strings in the Abelian Higgs model and compare them to CMB power spectra measured by Planck. We obtain revised constraints on the cosmic string tension parameter $G\\mu$. For example, in the $\\Lambda$CDM model with the addition of strings and no primordial tensor perturbations, we find $G\\mu < 2.0 \\times 10^{-7}$ at 95% confidence, about 20% lower than the value obtained from previous simulations, which had 1/64 of the spatial volume. We investigate the source of the difference, showing that the main cause is an improved treatment of the string evolution across the radiation-matter transition. The increased computational volume also makes possible to simulate fully the physical equations of motion, in which the string cores shrink in comoving coordinates. This, and the larger dynamic range, changes the amplitude of the power spectra by only about 10%, demonstrating that field theory simulations of cosmic s...
Bosonic condensates in realistic supersymmetric GUT cosmic strings
Allys, Erwan
2016-04-01
We study the realistic structure of F-term Nambu-Goto cosmic strings forming in a general supersymmetric Grand Unified Theory implementation, assuming standard hybrid inflation. Examining the symmetry breaking of the unification gauge group down to the Standard Model, we discuss the minimal field content necessary to describe abelian cosmic strings appearing at the end of inflation. We find that several fields will condense in most theories, questioning the plausible occurrence of associated currents (bosonic and fermionic). We perturbatively evaluate the modification of their energy per unit length due to the condensates. We provide a criterion for comparing the usual abelian Higgs approximation used in cosmology to realistic situations.
Using Cosmic Strings to Relate Local Geometry to Spatial Topology
Duston, Christopher L
2015-01-01
In this paper we will discuss how cosmic strings can be used to bridge the gap between the local geometry of our spacetime model and the global topology. The primary tool is the theory of foliations and surfaces, and together with observational constraints we can isolate several possibilities for the topology of the spatial section. This implies that the discovery of cosmic strings would not just be significant for an understanding of structure formation in the early universe, but also for the global properties of the spacetime model.
Black strings, low viscosity fluids, and violation of cosmic censorship.
Lehner, Luis; Pretorius, Frans
2010-09-01
We describe the behavior of 5-dimensional black strings, subject to the Gregory-Laflamme instability. Beyond the linear level, the evolving strings exhibit a rich dynamics, where at intermediate stages the horizon can be described as a sequence of 3-dimensional spherical black holes joined by black string segments. These segments are themselves subject to a Gregory-Laflamme instability, resulting in a self-similar cascade, where ever-smaller satellite black holes form connected by ever-thinner string segments. This behavior is akin to satellite formation in low-viscosity fluid streams subject to the Rayleigh-Plateau instability. The simulation results imply that the string segments will reach zero radius in finite asymptotic time, whence the classical space-time terminates in a naked singularity. Since no fine-tuning is required to excite the instability, this constitutes a generic violation of cosmic censorship. PMID:20867508
Black hole formation from collisions of cosmic strings
International Nuclear Information System (INIS)
We explain simple semi-classical rules to estimate the lifetime of any given highly excited quantum state of the string spectrum and apply them to identify new long-lived string states. Using analytic formulae for the string evolution after joining and interconnection, we study examples of fundamental cosmic string collisions leading to gravitational collapse. We find that the interconnection of two strings of equal and opposite maximal angular momenta and arbitrarily large mass generically leads to the formation of black holes. (Based on the works (Iengo and Russo 2006 J. High Energy Phys.JHEP02(2006)041, Iengo and Russo 2006 J. High Energy Phys.JHEP08(2006)079).)
Prolongation of Friction Dominated Evolution for Superconducting Cosmic Strings
International Nuclear Information System (INIS)
This investigation is concerned with cosmological scenarios based on particle physics theories that give rise to superconducting cosmic strings (whose subsequent evolution may produce stable loop configurations known as vortons). Cases in which electromagnetic coupling of the string current is absent or unimportant have been dealt with in previous work. The purpose of the present work is to provide quantitative estimates for cases in which electromagnetic interaction with the surrounding plasma significantly affects the string dynamics. In particular it will be shown that the current can become sufficiently strong for the initial period of friction dominated string motion to be substantially prolonged, which would entail a reinforcement of the short length scale end of the spectrum of the string distribution, with potentially observable cosmological implications if the friction dominated scenario lasts until the time of plasma recombination. (author)
The String and the Cosmic Bounce
Directory of Open Access Journals (Sweden)
Bozza V.
2014-04-01
Full Text Available String theory introduces a new fundamental scale (the string length that is expected to regularize the singularities of classical general relativity. In a cosmological context, the Big Bang is no longer regarded as the beginning of time, but just a transition between a Pre-Big Bang collapse phase and the current expansion. We will review old and recent attempts to build consistent bouncing cosmologies inspired to string theories, discussing their solved and unsolved problems, focussing on the observables that may distinguish them from standard inflationary scenarios.
Cosmic String Universes Embedded with Viscosity
Institute of Scientific and Technical Information of China (English)
Koijam Manihar Singh; Kangujam Priyokumar Singh
2011-01-01
We study string cosmological models with attached particles in LRS BI type space time.The dynamical and physical properties of such universes are studied,and the possibility that during the evolution of the universe the strings disappear,leaving only the particles,is also discussed.It is found that bulk viscosity plays a large role in the evolution of the universe.In these models we find critical instances of when there was a “Bounce”.The studied models are found to be of an inflationary type,and since a desirable feature of a meaningful string cosmological model is the presence of an inflationary epoch in the very early stages of evolution,our models can be thought of as realistic universes.The origin of the universe and the early stages of formation are still interesting areas of research.The concept of string theory was developed to describe the events of the early stages of the evolution of the universe.The universe can be described as a collection of extended (non point) objects.Thus,“string dust” cosmology will provide us with a model to investigate the properties related to this fact.%We study string cosmological models with attached particles in LRS BI type space time. The dynamical and physical properties of such universes are studied, and the possibility that during the evolution of the universe the strings disappear, leaving only the particles, is also discussed. It is found that bulk viscosity plays a large role in the evolution of the universe. In these models we find critical instances of when there was a "Bounce". The studied models are found to be of an inflationary type, and since a desirable feature of a meaningful string cosmological model is the presence of an inflationary epoch in the very early stages of evolution, our models can be thought of as realistic universes.
Small-angle CMB temperature anisotropies induced by cosmic strings
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We use Nambu-Goto numerical simulations to compute the cosmic microwave background (CMB) temperature anisotropies induced at arcminute angular scales by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW) expanding universe. We generate 84 statistically independent maps on a 7.2 deg. field of view, which we use to derive basic statistical estimators such as the one-point distribution and two-point correlation functions. At high multipoles, the mean angular power spectrum of string-induced CMB temperature anisotropies can be described by a power law slowly decaying as l-p, with p=0.889 (+0.001,-0.090) (including only systematic errors). Such a behavior suggests that a nonvanishing string contribution to the overall CMB anisotropies may become the dominant source of fluctuations at small angular scales. We therefore discuss how well the temperature gradient magnitude operator can trace strings in the context of a typical arcminute diffraction-limited experiment. Including both the thermal and nonlinear kinetic Sunyaev-Zel'dovich effects, the Ostriker-Vishniac effect, and the currently favored adiabatic primary anisotropies, we find that, on such a map, strings should be 'eye visible', with at least of order ten distinctive string features observable on a 7.2 deg. gradient map, for tensions U down to GU≅2x10-7 (in Planck units). This suggests that, with upcoming experiments such as the Atacama Cosmology Telescope (ACT), optimal non-Gaussian, string-devoted statistical estimators applied to small-angle CMB temperature or gradient maps may put stringent constraints on a possible cosmic string contribution to the CMB anisotropies.
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We present a significant update of the constraints on the Abelian Higgs cosmic string tension by cosmic microwave background (CMB) data, enabled both by the use of new high-resolution CMB data from suborbital experiments as well as the latest results of the WMAP satellite, and by improved predictions for the impact of Abelian Higgs cosmic strings on the CMB power spectra. The new cosmic string spectra [1] were improved especially for small angular scales, through the use of larger Abelian Higgs string simulations and careful extrapolation. If Abelian Higgs strings are present then we find improved bounds on their contribution to the CMB anisotropies, fdAH AH −6, both at 95% confidence level using WMAP7 data; and fdAH AH −6 using all the CMB data. We also find that using all the CMB data, a scale invariant initial perturbation spectrum, ns = 1, is now disfavoured at 2.4σ even if strings are present. A Bayesian model selection analysis no longer indicates a preference for strings
Large scale CMB anomalies from thawing cosmic strings
Ringeval, Christophe; Yokoyama, Jun'ichi; Bouchet, Francois R
2015-01-01
Cosmic strings formed during inflation are expected to be either diluted over super-Hubble distances, i.e., invisible today, or to have crossed our past light cone very recently. We discuss the latter situation in which a few strings imprint their signature in the Cosmic Microwave Background (CMB) Anisotropies after recombination. Being almost frozen in the Hubble flow, these strings are quasi static and evade almost all of the previously derived constraints on their tension while being able to source large scale anisotropies in the CMB sky. Using a local variance estimator on thousand of numerically simulated Nambu-Goto all sky maps, we compute the expected signal and show that it can mimic a dipole modulation at large angular scales while being negligible at small angles. Interestingly, such a scenario generically produces one cold spot from the thawing of a cosmic string loop. Mixed with anisotropies of inflationary origin, we find that a few strings of tension GU = O(1) x 10^(-6) match the amplitude of th...
Abelian Higgs cosmic strings: Small-scale structure and loops
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Classical lattice simulations of the Abelian Higgs model are used to investigate small-scale structure and loop distributions in cosmic string networks. Use of the field theory ensures that the small-scale physics is captured correctly. The results confirm analytic predictions of Polchinski and Rocha 29 for the two-point correlation function of the string tangent vector, with a power law from length scales of order the string core width up to horizon scale. An analysis of the size distribution of string loops gives a very low number density, of order 1 per horizon volume, in contrast with Nambu-Goto simulations. Further, our loop distribution function does not support the detailed analytic predictions for loop production derived by Dubath et al. 30. Better agreement to our data is found with a model based on loop fragmentation 32, coupled with a constant rate of energy loss into massive radiation. Our results show a strong energy-loss mechanism, which allows the string network to scale without gravitational radiation, but which is not due to the production of string width loops. From evidence of small-scale structure we argue a partial explanation for the scale separation problem of how energy in the very low frequency modes of the string network is transformed into the very high frequency modes of gauge and Higgs radiation. We propose a picture of string network evolution, which reconciles the apparent differences between Nambu-Goto and field theory simulations.
Analytic theory of discontinuities in current-carrying cosmic strings
Trojan, Ernst
2013-01-01
We formulate an analytic method to study the discontinuities in superconducting cosmic strings. Equations of discontinuities and conditions of their existence are derived from the intrinsic and extrinsic equations of motion. It is the fundamental for research of particular solutions, associated with kinks, cusps and shocks.
Stringy cosmic strings and compactifications of F-theory
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We construct stringy cosmic string solutions corresponding to compactifications of F-theory on several elliptic Calabi-Yau manifolds by solving the equations of motion of low energy effective action of ten-dimensional type IIB superstring theory. Existence of such solutions supports the compactifications of F-theory. (orig.)
Cosmic strings in an expanding spacetime
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We investigate the stability of a static, infinitely long and straight vacuum string solution under inhomogeneous axisymmetric time-dependent perturbations. We find it to be perturbatively stable. We further extend our work by finding a string solutions in an expanding Universe. The back reaction of the string on the gravitational field has been ignored. The background is assumed to be a Friedman-Robertson-Walker (FRW) cosmology. By numerically integrating the field equations in a radiation and matter dominated models, we discover oscillatory solutions. The possible damping of these oscillations is discussed. For late times the solution becomes identical to the static one studied in the first part of the paper. 19 refs., 8 figs
Abelian cosmic string in the extended Starobinsky model of gravity
Graça, J P Morais
2016-01-01
We analyze numerically the behaviour of the solutions corresponding to an Abelian cosmic string taking into account an extension of the Starobinsky model, where the action of general relativity is replaced by $f(R) = R - 2\\Lambda + \\eta R^2 + \\rho R^m$, with $m > 2$. As an interesting result, we find that the angular deficit which characterizes the cosmic string decreases as the parameters $\\eta$ and $\\rho$ increase. We also find that the cosmic horizon due to the presence of a cosmological constant is affected in such a way that it can grows or shrinks, depending on the vacuum expectation value of the scalar field and on the value of the cosmological constant
Spacetime of supermassive U(1)-gauge cosmic strings
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We investigate numerically the spacetime geometry in the presence of an infinitely long, straight, static, U(1)-gauge cosmic string formed during phase transitions at energy scales larger than the grand-unified-theory scale. As the energy scale of symmetry breaking increases, we find that at radial infinity the geometry around a string changes from Minkowskian minus a wedge to an analog of a Kasner spacetime. The geometry transition occurs at Δφ=2π, where the deficit angle Δφ is defined in the sense of comparison with flat spacetime in the absence of the string. Phase transitions producing such supermassive strings should occur before inflation to avoid contradictions with current observations
The stability of cosmic string loops
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A general perturbation analysis is performed on closed string loops to investigate whether small perturbations cause the known class of non-self-intersecting loops to self-intersect. This leads to the conclusion that most of this class of loops are stable to small perturbations. (orig.)
New solutions for non-Abelian cosmic strings
Hindmarsh, Mark; Weir, David J
2016-01-01
We study the properties of classical vortex solutions in a non-Abelian gauge theory. A system of two adjoint Higgs fields breaks the SU(2) gauge symmetry to $Z_2$, producing 't Hooft-Polyakov monopoles trapped on cosmic strings, termed beads; there are two charges of monopole and two degenerate string solutions. The strings break an accidental discrete $Z_2$ symmetry of the theory, explaining the degeneracy of the ground state. Further symmetries of the model, not previously appreciated, emerge when the masses of the two adjoint Higgs fields are degenerate. The breaking of the enlarged discrete symmetry gives rise to additional string solutions and splits the monopoles into four types of `semipole': kink solutions that interpolate between the string solutions, classified by a complex gauge invariant magnetic flux and a $Z_4$ charge. At special values of the Higgs self-couplings, the accidental symmetry broken by the string is continuous, giving rise to supercurrents on the strings. The SU(2) theory can be emb...
Topological Casimir effect in compactified cosmic string spacetime
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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)
Implications of cosmic strings with time-varying tension on CMB and large scale structure
Ichikawa, Kazuhide; Takahashi, Tomo; Yamaguchi, Masahide
2006-01-01
We investigate cosmological evolution and implications of cosmic strings with time-dependent tension. We derive basic equations of time development of the correlation length and the velocity of such strings, based on the one scale model. Then, we find that, in the case where the tension depends on some power of the cosmic time, cosmic strings with time-dependent tension goes into the scaling solution if the power is lower than a critical value. We also discuss cosmic microwave background anis...
CMB Anisotropy due to Cosmic Strings in an Accelerated Expanding Universe
Rokni, S Y; Bordbar, M R
2013-01-01
We want to find the cosmological constant influence on cosmic microwave background (CMB) anisotropy due to cosmic strings. Considering the space-time metric of a cosmic string under the effect of a positive cosmological constant, the CMB anisotropy is studied. The result shows that a positive cosmological constant (i.e. the presence of cosmic strings in an accelerated expanding universe) weakens the anisotropy so that more strong resolution is needed to detect the corresponding influences on the CMB power spectrum.
Correlations between black holes formed in cosmic string breaking
Emparan García de Salazar, Roberto A.
1995-01-01
An analysis of cosmic string breaking with the formation of black holes attached to the ends reveals a remarkable feature: the black holes can be correlated or uncorrelated. We find that, as a consequence, the number-of-states enhancement factor in the action governing the formation of uncorrelated black holes is twice the one for a correlated pair. We argue that when an uncorrelated pair forms at the ends of the string, the physics involved is more analogous to thermal nucleation than to par...
Gravitational fields of straight and circular cosmic strings
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This paper focuses on the relation between the gravitational mass, the angular deficit Δφ of the conical geometry and the internal structure of cosmic strings. For small angular deficits the conventional results derived from linear weak-field theory are confirmed. At larger angular deficits, the relation between Δφ and inertial mass becomes model-dependent, and the gravitational mass is smaller than predicted by linear theory. When Δφ approx-gt π the string loop is generally enclosed within a black hole
D-term cosmic strings from N = 2 supergravity
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We describe new half-BPS cosmic string solutions in N = 2, d = 4 supergravity coupled to one vector multiplet and one hypermultiplet. They are closely related to D-term strings in N = 1 supergravity. Fields of the N = 2 theory that are frozen in the solution contribute to the triplet moment map of the quaternionic isometries and leave their trace in N = 1 as a constant Fayet-Iliopoulos term. The choice of U(1) gauging and of special geometry are crucial. The construction gives rise to a non-minimal Kaehler potential and can be generalized to higher dimensional quaternionic-Kaehler manifolds
Cosmic optical activity in the spacetime of a scalar-tensor screwed cosmic string
Bezerra, V B
2003-01-01
Measurements of the quasars optical activities verify that their polarization vectors are not randomly oriented as naturally expected. In order to give a possible explanation to this phenomenon we investigate the role played by a Chern-Simons-type term in the scalar-tensor screwed cosmic string(SCS) background. In this scenario we discuss the possibility that the quasar optical polarization can be explained by considering that the electromagnetic waves emitted by these quasars interact with a scalar-tensor screwed cosmic string throught a Chern-Simons-type coupling. We use this screwed cosmic string to put limit in the coupling constant. The superconducting case has also been discussed and the results compared with general relativity effects.
Solution for a local straight cosmic string in the braneworld gravity
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In this work we deal with the spacetime shaped by a straight cosmic string, emerging from local gauge theories, in the braneworld gravity context. We search for physical consequences of string features due to the modified gravitational scenario encoded in the projected gravitational equations. It is shown that cosmic strings in braneworld gravity may present significant differences when compared to the general relativity predictions, since its linear density is modified and the deficit angle produced by the cosmic string is attenuated. Furthermore, the existence of cosmic strings in that scenario requires a strong restriction to the braneworld tension: λ ≥ 3 x 10-17, in Planck units. (orig.)
Solution for a local straight cosmic string in the braneworld gravity
Energy Technology Data Exchange (ETDEWEB)
Abdalla, M.C.B.; Carlesso, P.F. [UNESP, Universidade Estadual Paulista, Instituto de Fisica Teorica, Rua Dr. Bento Teobaldo Ferraz 271, Bloco II, Barra-Funda, Caixa Postal 70532-2, Sao Paulo, SP (Brazil); Hoff da Silva, J.M. [UNESP, Universidade Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil)
2015-09-15
In this work we deal with the spacetime shaped by a straight cosmic string, emerging from local gauge theories, in the braneworld gravity context. We search for physical consequences of string features due to the modified gravitational scenario encoded in the projected gravitational equations. It is shown that cosmic strings in braneworld gravity may present significant differences when compared to the general relativity predictions, since its linear density is modified and the deficit angle produced by the cosmic string is attenuated. Furthermore, the existence of cosmic strings in that scenario requires a strong restriction to the braneworld tension: λ ≥ 3 x 10{sup -17}, in Planck units. (orig.)
Dynamics of cosmic strings with higher-dimensional windings
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We consider F-strings with arbitrary configurations in the Minkowski directions of a higher-dimensional spacetime, which also wrap and spin around S1 subcycles of constant radius in an arbitrary internal manifold, and determine the relation between the higher-dimensional and the effective four-dimensional quantities that govern the string dynamics. We show that, for any such configuration, the motion of the windings in the compact space may render the string effectively tensionless from a four-dimensional perspective, so that it remains static with respect to the large dimensions. Such a critical configuration occurs when (locally) exactly half the square of the string length lies in the large dimensions and half lies in the compact space. The critical solution is then seen to arise as a special case, in which the wavelength of the windings is equal to their circumference. As examples, long straight strings and circular loops are considered in detail, and the solutions to the equations of motion that satisfy the tensionless condition are presented. These solutions are then generalized to planar loops and arbitrary three-dimensional configurations. Under the process of dimensional reduction, in which higher-dimensional motion is equivalent to an effective worldsheet current (giving rise to a conserved charge), this phenomenon may be seen as the analogue of the tensionless condition which arises for superconducting and chiral-current carrying cosmic strings
Discontinuity cylinder model of gravitating U(1) cosmic strings
Energy Technology Data Exchange (ETDEWEB)
Laguna-Castillo, P.; Matzner, R.A.
1987-05-15
We introduce a model for an infinite-length, straight U(1) cosmic string as a cylindrical, singular shell enclosing a region of false vacuum. The properties of the geometry for the region exterior to the string are fully determined under the assumption that changes in the scalar and gauge field variables occur only at the cylindrical shell. This is consistent with a limiting form of the scalar potential V(phi) where a minimum at chemically bondphichemically bond = 0 is separated by a large barrier from a global minimum at chemically bondphichemically bond = etanot =0. The introduction of an approximately singular ''surface'' for the string allows the definition of a delta-function stress-energy density that characterizes discontinuities in the fields. We show consistency of the model with the full coupled equations for the metric, and the scalar and gauge fields in curved space-time. It is found that for this model, in the absence of an ''external'' cosmological constant, the exterior geometry of the string approaches Minkowski space-time with a deficit angle, and it is shown that in the limit when the string becomes a line source, i.e., its radius vanishes, the deficit angle reduces to the well-known expression ..delta..theta = 8..pi mu.., with ..mu.. the proper mass per unit length of the string.
Dynamics of cosmic strings with higher-dimensional windings
Energy Technology Data Exchange (ETDEWEB)
Yamauchi, Daisuke [Research Center for the Early Universe, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Lake, Matthew J. [The Institute for Fundamental Study, “The Tah Poe Academia Institute' , Naresuan University, Phitsanulok 65000 (Thailand); Thailand Center of Excellence in Physics, Ministry of Education,Bangkok 10400 (Thailand)
2015-06-11
We consider F-strings with arbitrary configurations in the Minkowski directions of a higher-dimensional spacetime, which also wrap and spin around S{sup 1} subcycles of constant radius in an arbitrary internal manifold, and determine the relation between the higher-dimensional and the effective four-dimensional quantities that govern the string dynamics. We show that, for any such configuration, the motion of the windings in the compact space may render the string effectively tensionless from a four-dimensional perspective, so that it remains static with respect to the large dimensions. Such a critical configuration occurs when (locally) exactly half the square of the string length lies in the large dimensions and half lies in the compact space. The critical solution is then seen to arise as a special case, in which the wavelength of the windings is equal to their circumference. As examples, long straight strings and circular loops are considered in detail, and the solutions to the equations of motion that satisfy the tensionless condition are presented. These solutions are then generalized to planar loops and arbitrary three-dimensional configurations. Under the process of dimensional reduction, in which higher-dimensional motion is equivalent to an effective worldsheet current (giving rise to a conserved charge), this phenomenon may be seen as the analogue of the tensionless condition which arises for superconducting and chiral-current carrying cosmic strings.
Discontinuity cylinder model of gravitating U(1) cosmic strings
International Nuclear Information System (INIS)
We introduce a model for an infinite-length, straight U(1) cosmic string as a cylindrical, singular shell enclosing a region of false vacuum. The properties of the geometry for the region exterior to the string are fully determined under the assumption that changes in the scalar and gauge field variables occur only at the cylindrical shell. This is consistent with a limiting form of the scalar potential V(phi) where a minimum at chemical bondphichemical bond = 0 is separated by a large barrier from a global minimum at chemical bondphichemical bond = etanot =0. The introduction of an approximately singular ''surface'' for the string allows the definition of a δ-function stress-energy density that characterizes discontinuities in the fields. We show consistency of the model with the full coupled equations for the metric, and the scalar and gauge fields in curved space-time. It is found that for this model, in the absence of an ''external'' cosmological constant, the exterior geometry of the string approaches Minkowski space-time with a deficit angle, and it is shown that in the limit when the string becomes a line source, i.e., its radius vanishes, the deficit angle reduces to the well-known expression Δθ = 8πμ, with μ the proper mass per unit length of the string
Cosmic string in compactified gauge theory
International Nuclear Information System (INIS)
A solution of the vortex type is given in a six-dimensional SU(2)xU(1) pure gauge theory coupled to Einstein gravity in a compactified background geometry. We construct the solution of an effective Abelian-Higgs model in terms of dimensional reduction. The solution, however, has a peculiarity in its physically relevant quantity, a deficit angle, which is given as a function of the ratio of the gauge couplings of SU(2) and U(1). The size of the extra space (sphere) is shown to vary with the distance from the axis of the 'string'. (author)
Is it really naked? On cosmic censorship in string theory
International Nuclear Information System (INIS)
We investigate the possibility of cosmic censorship violation in string theory using a characteristic double-null code, which penetrates horizons and is capable of resolving the spacetime all the way to the singularity. We perform high-resolution numerical simulations of the evolution of negative mass initial scalar field profiles, which were argued to provide a counterexample to cosmic censorship conjecture for AdS-asymptotic spacetimes in five-dimensional supergravity. In no instances formation of naked singularity is seen. Instead, numerical evidence indicates that black holes form in the collapse. Our results are consistent with earlier numerical studies, and explicitly show where the 'no black hole' argument breaks
DF-strings from D3${\\bar {\\bf D}}$3 as Cosmic Strings
Cho, I; Kyae, B; Cho, Inyong; Kim, Yoonbai; Kyae, Bumseok
2006-01-01
We study Dirac-Born-Infeld type effective field theory of a complex tachyon and U(1)$\\times$U(1) gauge fields describing a D3${\\bar {\\rm D}}$3 system. Classical solutions of straight global and local DF-strings with quantized vorticity are found and are classified into two types by the asymptotic behavior of the tachyon amplitude. For sufficiently large radial distances, one has linearly-growing tachyon amplitude and the other logarithmically-growing tachyon amplitude. A constant radial electric flux density denoting the fundamental-string background makes the obtained DF-strings thick. The other electric flux density parallel to the strings is localized, which represents localization of fundamental strings in the D1-F1 bound states. Since these DF-strings are formed in the coincidence limit of the D3${\\bar {\\rm D}}$3, these cosmic DF-strings are safe from inflation induced by the approach of the separated D3 and ${\\bar {\\rm D}}3$.
Rotating black holes pierced by a cosmic string
Kubiznak, David
2015-01-01
A rotating black hole threaded by an infinitely long cosmic string is studied in the framework of the Abelian Higgs model. We show that contrary to a common belief in the presence of rotation the backreaction of the string does not induce a simple conical deficit. This leads to new distinct features of the Kerr--string system such as modified ISCO or shifted ergosphere, though these effects are most likely outside the range of observational precision. For an extremal rotating black hole, the system exhibits a first-order phase transition for the gravitational Meissner effect: small black holes exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon, whereas the horizon of large black holes is pierced by the vortex. A brief review prepared for the MG14 Proceedings.
Cosmic R-string, R-tube and vacuum instability
Energy Technology Data Exchange (ETDEWEB)
Eto, Minoru [Yamagata Univ. (Japan). Dept. of Physics; Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ohashi, Keisuke [Osaka City Univ. (Japan). Dept. of Mathematics and Physics; Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research
2012-11-15
We show that a cosmic string associated with spontaneous U(1) R symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a ''bamboo''-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.
Disruption of Cosmic String Wakes by Gaussian Fluctuations
Brandenberger, Robert H; da Cunha, Disrael C N
2015-01-01
We study the stability of cosmic string wakes against the disruption by the dominant Gaussian fluctuations which are present in cosmological models. We find that for a string tension given by $G \\mu = 10^{-7}$ wakes remain locally stable until a redshift of $z = 6$, and for a value of $G \\mu = 10^{-14}$ they are stable beyond a redshift of $z = 20$. We study a global stability criterion which shows that wakes created by strings at times after $t_{eq}$ are identifiable up to the present time, independent of the value of $G \\mu$. Taking into account our criteria it is possible to develop strategies to search for the distinctive position space signals in cosmological maps which are induced by wakes.
Cosmic R-string, R-tube and vacuum instability
International Nuclear Information System (INIS)
We show that a cosmic string associated with spontaneous U(1) R symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a ''bamboo''-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.
Cosmic R-string, R-tube and vacuum instability
Eto, Minoru; Hamada, Yuta; Kamada, Kohei; Kobayashi, Tatsuo; Ohashi, Keisuke; Ookouchi, Yutaka
2013-03-01
We show that a cosmic string associated with spontaneous U(1) R symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a "bamboo"-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.
Cosmic R-string, R-tube and Vacuum Instability
Eto, Minoru; Kamada, Kohei; Kobayashi, Tatsuo; Ohashi, Keisuke; Ookouchi, Yutaka
2012-01-01
We show that a cosmic string associated with spontaneous $U(1)_R$ symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a "bamboo"-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.
General relativistic model of a spinning cosmic string
International Nuclear Information System (INIS)
The authors investigate the infinite, straight, rotating cosmic string within the framework of Einstein's General Theory of Relativity. A class of exact interior solutions is derived for which the source satisfies the weak and the dominant energy conditions. The interior metric is matched smoothly to the exterior vacuum. A subclass of these solutions has closed time-like curves both in the interior and the exterior geometry. 39 refs., 2 figs
The COBE cosmic 3 K anisotropy experiment: A gravity wave and cosmic string probe
Bennett, Charles L.; Smoot, George F.
1989-01-01
Among the experiments to be carried into orbit next year, by the COBE satellite, are differential microwave radiometers. They will make sensitive all-sky maps of the temperature of the cosmic microwave background radiation at three frequencies, giving dipole, quadrupole, and higher order multipole measurements of the background radiation. The experiment will either detect, or place significant constraints on, the existence of cosmic strings and long wavelength gravity waves.
Search for Cosmic Strings in the GOODS Survey
Christiansen, J L; James, K A; Goldman, J; Maruyama, D; Smoot, G F
2008-01-01
We search Hubble Space Telescope Treasury Program images collected as part of the Great Observatories Origins Deep Survey for pairs of galaxies consistent with the gravitational lensing signature of a cosmic string. Our technique includes estimates of the efficiency for finding the lensed galaxy pair. In the North (South) survey field we find no evidence out to a redshift of greater than 1 (0.5) for cosmic strings to a mass per unit length limit of $G\\mu<3.0x10^{-7}$ at 95% CL. In the combined 314.9 arcmin$^2$ of the North and South survey fields this corresponds to a limit on $\\Omega_{strings}<0.0056$. Our global limit on $G\\mu$ is more than an order of magnitude lower than searches for individual strings in CMB data. Our limit is higher than other CMB and gravitational wave searches, however we note that it is less model dependent than these other searches.
Constraints on cosmic (super)strings from the LIGO-Virgo gravitational-wave detectors
Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Adams, C; Adams, T; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Allen, B; Allocca, A; Ceron, E Amador; Amariutei, D; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barker, D; Barnum, S H; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Bell, C; Belopolski, I; Bergmann, G; Berliner, J M; Bersanetti, D; Bertolini, A; Bessis, D; Betzwieser, J; Beyersdorf, P T; Bhadbhade, T; Bilenko, I A; Billingsley, G; Birch, J; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Bowers, J; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brannen, C A; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavagliá, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Colombini, M; Constancio, M; Conte, A; Conte, R; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Craig, K; Creighton, J D E; Creighton, T D; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; De Rosa, R; Debreczeni, G; Degallaix, J; Del Pozzo, W; Deleeuw, E; Deléglise, S; Denker, T; Dent, T; Dereli, H; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Díaz, M; Dietz, A; Dmitry, K; Donovan, F; Dooley, K L; Doravari, S; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dumas, J -C; Dwyer, S; Eberle, T; Edwards, M; Effler, A; Ehrens, P; Eichholz, J; Eikenberry, S S; Endröczi, G; Essick, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farinon, S; Farr, B; Farr, W; Favata, M; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R; Flaminio, R; Foley, E; Foley, S; Forsi, E; Fotopoulos, N; Fournier, J -D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fujimoto, M -K; Fulda, P; Fyffe, M; Gair, J; Gammaitoni, L; Garcia, J; Garufi, F; Gehrels, N; Gemme, G; Genin, E; Gennai, A; Gergely, L; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gil-Casanova, S; Gill, C; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Griffo, C; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gushwa, K E; Gustafson, E K; Gustafson, R; Hall, B; Hall, E; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Heefner, J; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Holtrop, M; Hong, T; Hooper, S; Horrom, T; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hua, Z; Huang, V; Huerta, E A; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Iafrate, J; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jang, Y J; Jaranowski, P; Jiménez-Forteza, F; Johnson, W W; Jones, D; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasprzack, M; Kasturi, R; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufman, K; Kawabe, K; Kawamura, S; Kawazoe, F; Kéfélian, F; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, B K; Kim, C; Kim, K; Kim, N; Kim, W; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D; Kremin, A; Kringel, V; Królak, A; Kucharczyk, C; Kudla, S; Kuehn, G; Kumar, A; Kumar, P; Kumar, R; Kurdyumov, R; Kwee, P; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lawrie, C; Lazzarini, A; Roux, A Le; Leaci, P; Lebigot, E O; Lee, C -H; Lee, H K; Lee, H M; Lee, J; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levine, B; Lewis, J B; Lhuillier, V; Li, T G F; Lin, A C; Littenberg, T B; Litvine, V; Liu, F; Liu, H; Liu, Y; Liu, Z; Lloyd, D; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Luan, J; Lubinski, M J; Lück, H; Lundgren, A P; Macarthur, J; Macdonald, E; Machenschalk, B; MacInnis, M; Macleod, D M; Magana-Sandoval, F; Mageswaran, M; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; 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2013-01-01
Cosmic string cusps produce powerful bursts of gravitational waves (GWs). These bursts provide the most promising observational signature of cosmic strings. In this letter we report stringent limits on cosmic string models obtained from the analysis of 625 days of observation with the LIGO and Virgo GW detectors. A significant fraction of the cosmic string parameter space is ruled out. This result complements and improves existing limits from searches for a stochastic background of GWs using cosmic microwave background and pulsar timing data. In particular, if the size of loops is given by gravitational back-reaction, we place upper limits on the string tension $G\\mu$ below $10^{-8}$ in some regions of the cosmic string parameter space.
Constraints on Cosmic Strings from the LIGO-Virgo Gravitational-Wave Detectors
Aasi, J.; Abadie, J.; Abbott, B.P.; Abbott, R.; Abbott, T.; Abernathy, M.R.; Accadia, T.; Adams, C.; Adams, T.; Adhikari, R.X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O.D.; Ajith, P.; Allen, B.; Allocca, A.; Ceron, E.A.; Amariutei, D.; Anderson, S.B.; Blackburn, L.; Camp, J.B.; Gehrels, N.; Graff, P.B.; Kanner, J.B.
2014-01-01
Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension (Newton's Constant x mass per unit length) below 10(exp -8) in some regions of the cosmic string parameter space.
Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors.
Aasi, J; Abadie, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Adams, C; Adams, T; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Allen, B; Allocca, A; Amador Ceron, E; Amariutei, D; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barker, D; Barnum, S H; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J; Bauchrowitz, J; Bauer, Th S; Bebronne, M; Behnke, B; Bejger, M; Beker, M G; Bell, A S; Bell, C; Belopolski, I; Bergmann, G; Berliner, J M; Bersanetti, D; Bertolini, A; Bessis, D; Betzwieser, J; Beyersdorf, P T; Bhadbhade, T; Bilenko, I A; Billingsley, G; Birch, J; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Bowers, J; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brannen, C A; Brau, J E; Breyer, J; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Calderón Bustillo, J; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Colombini, M; Constancio, M; Conte, A; Conte, R; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J-P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Craig, K; Creighton, J D E; Creighton, T D; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Dal Canton, T; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; De Rosa, R; Debreczeni, G; Degallaix, J; Del Pozzo, W; Deleeuw, E; Deléglise, S; Denker, T; Dent, T; Dereli, H; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Díaz, M; Dietz, A; Dmitry, K; Donovan, F; Dooley, K L; Doravari, S; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dumas, J-C; Dwyer, S; Eberle, T; Edwards, M; Effler, A; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, K; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farinon, S; Farr, B; Farr, W; Favata, M; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R; Flaminio, R; Foley, E; Foley, S; Forsi, E; Fotopoulos, N; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fujimoto, M-K; Fulda, P; Fyffe, M; Gair, J; Gammaitoni, L; Garcia, J; Garufi, F; Gehrels, N; Gemme, G; Genin, E; Gennai, A; Gergely, L; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gil-Casanova, S; Gill, C; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Griffo, C; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C; Gushwa, K E; Gustafson, E K; Gustafson, R; Hall, B; Hall, E; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Heefner, J; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Holtrop, M; Hong, T; Hooper, S; Horrom, T; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hua, Z; Huang, V; Huerta, E A; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Iafrate, J; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jang, Y J; Jaranowski, P; Jiménez-Forteza, F; Johnson, W W; Jones, D; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kasprzack, M; Kasturi, R; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufman, K; Kawabe, K; Kawamura, S; Kawazoe, F; Kéfélian, F; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, B K; Kim, C; Kim, K; Kim, N; Kim, W; Kim, Y-M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D; Kremin, A; Kringel, V; Królak, A; Kucharczyk, C; Kudla, S; Kuehn, G; Kumar, A; Kumar, P; Kumar, R; Kurdyumov, R; Kwee, P; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lawrie, C; Lazzarini, A; Le Roux, A; Leaci, P; Lebigot, E O; Lee, C-H; Lee, H K; Lee, H M; Lee, J; Lee, J; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levine, B; Lewis, J B; Lhuillier, V; Li, T G F; Lin, A C; Littenberg, T B; Litvine, V; Liu, F; Liu, H; Liu, Y; Liu, Z; Lloyd, D; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Luan, J; Lubinski, M J; Lück, H; Lundgren, A P; Macarthur, J; Macdonald, E; Machenschalk, B; MacInnis, M; Macleod, D M; Magana-Sandoval, F; Mageswaran, M; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Matzner, R A; Mavalvala, N; May, G; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meier, T; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyer, M S; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Miller, J; Minenkov, Y; Mingarelli, C M F; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Mohan, M; Mohapatra, S R P; Mokler, F; Moraru, D; Moreno, G; Morgado, N; Mori, T; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Nanda Kumar, D; Nardecchia, I; Nash, T; Naticchioni, L; Nayak, R; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nishida, E; Nishizawa, A; Nitz, A; Nocera, F; Nolting, D; Normandin, M E; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oppermann, P; O'Reilly, B; Ortega Larcher, W; O'Shaughnessy, R; Osthelder, C; Ott, C D; Ottaway, D J; Ottens, R S; Ou, J; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palomba, C; Pan, Y; Pankow, C; Paoletti, F; Paoletti, R; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Peiris, P; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pindor, B; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poole, V; Poux, C; Predoi, V; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Quetschke, V; Quintero, E; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Rapagnani, P; Raymond, V; Re, V; Reed, C M; Reed, T; Regimbau, T; Reid, S; Reitze, D H; Ricci, F; Riesen, R; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Roddy, S; Rodriguez, C; Rodruck, M; Roever, C; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Schilling, R; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schulz, B; Schutz, B F; Schwinberg, P; Scott, J; Scott, S M; Seifert, F; Sellers, D; Sengupta, A S; Sentenac, D; Sergeev, A; Shaddock, D; Shah, S; Shahriar, M S; Shaltev, M; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Sintes, A M; Skelton, G R; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, R J E; Smith-Lefebvre, N D; Soden, K; Son, E J; Sorazu, B; Souradeep, T; Sperandio, L; Staley, A; Steinert, E; Steinlechner, J; Steinlechner, S; Steplewski, S; Stevens, D; Stochino, A; Stone, R; Strain, K A; Straniero, N; Strigin, S; Stroeer, A S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Szeifert, G; Tacca, M; Talukder, D; Tang, L; Tanner, D B; Tarabrin, S P; Taylor, R; ter Braack, A P M; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Toncelli, A; Tonelli, M; Torre, O; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Ugolini, D; Unnikrishnan, C S; Vahlbruch, H; Vajente, G; Vallisneri, M; van den Brand, J F J; Van Den Broeck, C; van der Putten, S; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Verma, S; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J-Y; Vitale, S; Vlcek, B; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vrinceanu, D; Vyachanin, S P; Wade, A; Wade, L; Wade, M; Waldman, S J; Walker, M; Wallace, L; Wan, Y; Wang, J; Wang, M; Wang, X; Wanner, A; Ward, R L; Was, M; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D J; Whiting, B F; Wibowo, S; Wiesner, K; Wilkinson, C; Williams, L; Williams, R; Williams, T; Willis, J L; Willke, B; Wimmer, M; Winkelmann, L; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Worden, J; Yablon, J; Yakushin, I; Yamamoto, H; Yancey, C C; Yang, H; Yeaton-Massey, D; Yoshida, S; Yum, H; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J-P; Zhang, F; Zhang, L; Zhao, C; Zhu, H; Zhu, X J; Zotov, N; Zucker, M E; Zweizig, J
2014-04-01
Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space. PMID:24745400
Scaling and small-scale structure in cosmic string networks
International Nuclear Information System (INIS)
We examine the scaling properties of an evolving network of strings in Minkowski spacetime and study the evolution of length scales in terms of a three-scale model proposed by Austin, Copeland, and Kibble (ACK). We find good qualitative and some quantitative agreement between the model and our simulations. We also investigate small-scale structure by altering the minimum allowed size for loop production Ec. Certain quantities depend significantly on this parameter: for example, the scaling density can vary by a factor of 2 or more with increasing Ec. Small-scale structure as defined by ACK disappears if no restrictions are placed on loop production, and the fractal dimension of the string changes smoothly from 2 to 1 as the resolution scale is decreased. Loops are nearly all produced at the lattice cutoff. We suggest that the lattice cutoff should be interpreted as corresponding to the string width, and that in a real network loops are actually produced with this size. This leads to a radically different string scenario, with particle production rather than gravitational radiation being the dominant mode of energy dissipation. At the very least, a better understanding of the discretization effects in all simulations of cosmic strings is called for. copyright 1997 The American Physical Society
Cosmic Strings in the Abelian Higgs Model with Conformal Coupling to Gravity
Verbin, Y.
1998-01-01
Cosmic string solutions of the abelian Higgs model with conformal coupling to gravity are shown to exist. The main characteristics of the solutions are presented and the differences with respect to the minimally coupled case are studied. An important difference is the absence of Bogomolnyi cosmic string solutions for conformal coupling. Several new features of the abelian Higgs cosmic strings of both types are discussed. The most interesting is perhaps a relation between the angular deficit a...
Impact of radiative decay on cosmic string dynamics at small scales
Stuckey, Stephanie
2012-01-01
Cosmic strings are topological defects appearing as extended solutions in many high energy physics scenarios. Observation of signatures expected due to the presence of cosmic string networks could provide critical evidence in distinguishing and constraining fundamental cosmological and particle physics theories. Large scale evolution of cosmic string is well understood but the dynamics influenced by small scale structure remains unclear. Radiation back-reaction is expected t...
Energy-momentum correlations for Abelian Higgs cosmic strings
Daverio, David; Hindmarsh, Mark; Kunz, Martin; Lizarraga, Joanes; Urrestilla, Jon
2016-04-01
We report on the energy-momentum correlators obtained with recent numerical simulations of the Abelian Higgs model, essential for the computation of cosmic microwave background and matter perturbations of cosmic strings. Due to significant improvements both in raw computing power and in our parallel simulation framework, the dynamical range of the simulations has increased fourfold both in space and time, and for the first time we are able to simulate strings with a constant physical width in both the radiation and matter eras. The new simulations improve the accuracy of the measurements of the correlation functions at the horizon scale and confirm the shape around the peak. The normalization is slightly higher in the high wave-number tails, due to a small increase in the string density. We study, for the first time, the behavior of the correlators across cosmological transitions and discover that the correlation functions evolve adiabatically; i.e., the network adapts quickly to changes in the expansion rate. We propose a new method for constructing source functions for Einstein-Boltzmann integrators, comparing it with two other methods previously used. The new method is more consistent, easier to implement, and significantly more accurate.
Energy-momentum correlations for Abelian Higgs cosmic strings
Daverio, David; Kunz, Martin; Lizarraga, Joanes; Urrestilla, Jon
2015-01-01
We report on the energy-momentum correlators obtained with recent numerical simulations of the Abelian Higgs model, essential for the computation of cosmic microwave background and matter perturbations of cosmic strings. Due to significant improvements both in raw computing power and in our parallel simulation framework, the dynamical range of the simulations has increased four-fold both in space and time, and for the first time we are able to simulate strings with a constant physical width in both the radiation and matter eras. The new simulations improve the accuracy of the measurements of the correlation functions at the horizon scale and confirm the shape around the peak. The normalization is slightly higher in the high wave-number tails, due to a small increase in the string density. We study for the first time the behaviour of the correlators across cosmological transitions, and discover that the correlation functions evolve adiabatically, ie the network adapts quickly to changes in the expansion rate. ...
CMB polarization power spectra contributions from a network of cosmic strings
International Nuclear Information System (INIS)
We present the first calculation of the possible (local) cosmic string contribution to the cosmic microwave background polarization spectra from simulations of a string network (rather than a stochastic collection of unconnected string segments). We use field-theory simulations of the Abelian Higgs model to represent local U(1) strings, including their radiative decay and microphysics. Relative to previous estimates, our calculations show a shift in power to larger angular scales, making the chance of a future cosmic string detection from the B-mode polarization slightly greater. We explore a future ground-based polarization detector, taking the CLOVER project as our example. In the null hypothesis (that cosmic strings make a zero contribution) we find that CLOVER should limit the string tension μ to Gμ-6 (where G is the gravitational constant), above which it is likely that a detection would be possible
Abelian Higgs Cosmic Strings: Small Scale Structure and Loops
Hindmarsh, Mark; Bevis, Neil
2008-01-01
Classical lattice simulations of the Abelian Higgs model are used to investigate small scale structure and loop distributions in cosmic string networks. Use of the field theory ensures that the small-scale physics is captured correctly. The results confirm analytic predictions of Polchinski & Rocha [1] for the two-point correlation function of the string tangent vector, with a power law from length scales of order the string core width up to horizon scale with evidence to suggest that the small scale structure builds up from small scales. An analysis of the size distribution of string loops gives a very low number density, of order 1 per horizon volume, in contrast with Nambu-Goto simulations. Further, our loop distribution function does not support the detailed analytic predictions for loop production derived by Dubath et al. [2]. Better agreement to our data is found with a model based on loop fragmentation [3], coupled with a constant rate of energy loss into massive radiation. Our results show a stron...
Negative energy in string theory and cosmic censorship violation
International Nuclear Information System (INIS)
We find asymptotically anti-de Sitter solutions in N=8 supergravity which have a negative total energy. This is possible since the boundary conditions required for the positive energy theorem are stronger than those required for a finite mass (and allowed by string theory). But the stability of the anti-de Sitter vacuum is still ensured by the positivity of a modified energy, which includes an extra surface term. Some of the negative energy solutions describe the classical evolution of nonsingular initial data to naked singularities. Since there is an open set of such solutions, cosmic censorship is violated generically in supergravity. Using the dual field theory description, we argue that these naked singularities will be resolved in the full string theory
Gravitational back reaction on piecewise linear cosmic string loops
Wachter, Jeremy M
2016-01-01
We calculate the metric and affine connection due to a piecewise linear cosmic string loop, and the effect of gravitational back reaction for the Garfinkle-Vachaspati loop with four straight segments. As expected, back reaction reduces the size of the loop, in accord with the energy going into gravitational waves. The "square" loop whose generators lie at right angles evaporates without changing shape, but in all other cases, the kinks become less sharp and segments between kinks become curved. If the loop is close to the square case, the loop will evaporate before its kinks are significantly changed; if it is far from square, the opening out of the kinks is much faster than evaporation of the loop. In more realistic loops, the curvature of the straight segments due to gravitational back reaction may lead to cusps which did not exist in the original shape with the bending of the string concentrated at kinks.
Repulsive Casimir-Polder forces from cosmic strings
Saharian, A A
2011-01-01
We investigate the Casimir-Polder force acting on a polarizable microparticle in the geometry of a straight cosmic string. In order to develop this analysis we evaluate the electromagnetic field Green tensor on the imaginary frequency axis. The expression for the Casimir-Polder force is derived in the general case of anisotropic polarizability. In dependence of the eigenvalues for the polarizability tensor and of the orientation of its principal axes, the Casimir-Polder force can be either repulsive or attractive. Moreover, there are situations where the force changes the sign with separation. We show that for an isotropic polarizability tensor the force is always repulsive. At large separations between the microparticle and the string, the force varies inversely as the fifth power of the distance. In the non-retarded regime, corresponding to separations smaller than the relevant transition wavelengths, the force decays as the inverse fourth power of the distance. In the case of anisotropic polarizability, th...
Radiative non-Abelian cosmic strings with negative cosmological constant
International Nuclear Information System (INIS)
We investigated the SU(2) Einstein-Yang-Mills system with a cosmological constant on a time-dependent non-diagonal cylindrical symmetric spacetime. Only for suitable negative Λ and specific initial values, we find numerically regular wave-like solutions dressed with both electric and magnetic charges. The cosmic string feature is maintained by the finite angle deficit the solutions possess. In general the solution will develop a cosmological horizon; however, it resolves for increasing negative values of the cosmological constant and increasing time. Further, the features of the dyon depend on the angular momentum flux
Is it Really Naked? On Cosmic Censorship in String Theory
Energy Technology Data Exchange (ETDEWEB)
Frolov, A
2004-09-30
We investigate the possibility of cosmic censorship violation in string theory using a characteristic double-null code, which penetrates horizons and is capable of resolving the spacetime all the way to the singularity. We perform high-resolution numerical simulations of the evolution of negative mass initial scalar field profiles, which were argued to provide a counter example to cosmic censorship conjecture for AdS-asymptotic spacetimes in five-dimensional supergravity. In no instances formation of naked singularity is seen. Instead, numerical evidence indicates that black holes form in the collapse. Our results are consistent with earlier numerical studies, and explicitly show where the ''no black hole'' argument breaks.
Implications of fast radio bursts for superconducting cosmic strings
International Nuclear Information System (INIS)
Highly beamed, short-duration electromagnetic bursts could be produced by superconducting cosmic string (SCS) loops oscillating in cosmic magnetic fields. We demonstrated that the basic characteristics of SCS bursts such as the electromagnetic frequency and the energy release could be consistently exhibited in the recently discovered fast radio bursts (FRBs). Moreover, it is first showed that the redshift distribution of the FRBs can also be well accounted for by the SCS burst model. Such agreements between the FRBs and SCS bursts suggest that the FRBs could originate from SCS bursts and thus they could provide an effective probe to study SCSs. The obtained values of model parameters indicate that the loops generating the FRBs have a small length scale and they are mostly formed in the radiation-dominated cosmological epoch
On Bianchi-I cosmic strings coupled with Maxwell ﬁelds in bimetric relativity
Indian Academy of Sciences (India)
V Mahurpawar; S D Deo
2003-10-01
Axially symmetric Bianchi-I model is studied with source cosmic cloud strings coupled with electromagnetic ﬁeld in Rosen’s bimetric theory of relativity and observed that there is no contribution from cosmic strings and Maxwell ﬁelds in this theory.
Sini, R; Kuriakose, V C
2008-01-01
Dirac equation for a general black hole metric having a cosmic string in the back ground is derived. We evaluate quasi normal mode frequencies for Schwarzschild, RN extremal, SdS and near extremal SdS black hole space times with cosmic string perturbed by a massless Dirac field, using WKB approximation.
Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy
Pogosian, Levon; Wasserman, Ira; Wyman, Mark
2008-01-01
Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (l2000) will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.
Detecting cosmic string passage through the Earth by consequent global earthquake
Motohashi, Hayato
2013-01-01
Effects invoked by the passage of the cosmic string through the Earth are investigated. The cosmic string induces global oscillations of the Earth whose amplitude and acceleration both linearly depend on the string line density. For the line density maximally allowed by the cosmic observations, the oscillations are perceivable even to human beings and may cause serious damages to the environment. Use of the sophisticated accelerograph enables us to detect the string of a line density down to ten orders of magnitude smaller than the cosmologically relevant value.
Closed timelike curves produced by pairs of moving cosmic strings - Exact solutions
Gott, J. Richard, III
1991-01-01
Exact solutions of Einstein's field equations are presented for the general case of two moving straight cosmic strings that do not intersect. The solutions for parallel cosmic strings moving in opposite directions show closed timelike curves (CTCs) that circle the two strings as they pass, allowing observers to visit their own past. Similar results occur for nonparallel strings, and for masses in (2+1)-dimensional spacetime. For finite string loops the possibility that black-hole formation may prevent the formation of CTCs is discussed.
Circular Loop Equation of a Cosmic String in Gauss–Bonnet–de Sitter Spacetimes
International Nuclear Information System (INIS)
We perform the analysis of evolution of cosmic string loops in the background of Gauss–Bonnet–de Sitter. The equation of motion of cosmic string loops in this spacetime is derived. Having solved the equation numerically we investigate the dependence of the loop evolution on the values of α, related to the Gauss–Bonnet coupling. In the Gauss–Bonnet–de Sitter spacetimes with different dimensionality there exists a special parameter αm. In the environment with α > αm, all the cosmic string loops will collapse to form black holes. Within the region 0 m, the stronger Gauss–Bonnet effect will lead more cosmic string loops, including smaller ones, to form black holes. The larger the value of α is, the smaller the special values that exist, and only the cosmic string loops with initial radius larger than the special values can expand and evolve instead of becoming black holes
Induced vacuum current and magnetic field in the background of a cosmic string
International Nuclear Information System (INIS)
Vacuum polarization effects in the cosmic string background are considered. We find that a current is induced in the vacuum of the quantized massive scalar field and that the current circulates around the string which is generalized to a (d - 2)-brane in locally flat (d + 1)-dimensional spacetime. As a consequence of the Maxwell equation, a magnetic field strength is also induced in the vacuum and is directed along the cosmic string. The dependence of the current and the field strength on the string flux and tension is comprehensively analysed. Both the current and the field strength are holomorphic functions of the space dimension, decreasing exponentially with the distance from the string. In the case of d = 3 we show that, due to the vacuum polarization, the cosmic string is enclosed in a tube of the magnetic flux lines if the mass of the quantized field is less than the inverse of the transverse size of the string core.
Cosmic strings and the formation of galaxies and clusters of galaxies
International Nuclear Information System (INIS)
The evolution of density perturbations around cosmic strings in the matter-dominated era is discussed with attention to the specific nature of string perturbations. The parameter Gμ is calculated in two completely independent ways: from the requirements that Abell clusters are formed and that the galaxy-galaxy correlation function matches the observed one. Both values are consistent, lending support to the cosmic string theory
Anisotropies in the gravitational wave background as a probe of the cosmic string network
Kuroyanagi, Sachiko; Yonemaru, Naoyuki; Kumamoto, Hiroki
2016-01-01
Pulsar timing arrays are one of the powerful tools to test the existence of cosmic strings through searching for the gravitational wave background. The amplitude of the background connects to information on cosmic strings such as the tension and string network properties. In addition, one may be able to extract more information on properties of cosmic strings by measuring anisotropies in the gravitational wave (GW) background. In this paper, we provide estimates of the level of anisotropy expected in the GW background generated by cusps on cosmic strings. We find that the anisotropy level strongly depends on the initial loop size $\\alpha$, and thus we may be able to put constraint on $\\alpha$ by measuring the anisotropy of the GW background. We also find that certain regions of the parameter space can be probed by shifting the observation frequency of GWs.
Cosmic strings as the source of small-scale microwave background anisotropy
Pogosian, Levon; Tye, S.-H. Henry; Wasserman, Ira; Wyman, Mark
2009-02-01
Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy seeded by inflation. The spectrum of perturbations generated by strings does not match the observed CMB spectrum on large angular scales (ell < 1000) and is bounded to contribute no more than 10% of the total power on those scales. However, when this bound is marginally saturated, the anisotropy created by cosmic strings on small angular scales ell gtrsim 2000 will dominate over that created by the primary inflationary perturbations. This range of angular scales in the CMB is presently being measured by a number of experiments; their results will test this prediction of cosmic string networks soon.
Repulsive Casimir-Polder forces from cosmic strings
International Nuclear Information System (INIS)
We investigate the Casimir-Polder force acting on a polarizable microparticle in the geometry of a straight cosmic string. In order to develop this analysis we evaluate the electromagnetic field Green tensor on the imaginary frequency axis. The expression for the Casimir-Polder force is derived in the general case of anisotropic polarizability. In dependence on the eigenvalues for the polarizability tensor and of the orientation of its principal axes, the Casimir-Polder force can be either repulsive or attractive. Moreover, there are situations where the force changes the sign with separation. We show that for an isotropic polarizability tensor the force is always repulsive. At large separations between the microparticle and the string, the force varies inversely with the fifth power of the distance. In the non-retarded regime, corresponding to separations smaller than the relevant transition wavelengths, the force decays with the inverse fourth power of the distance. In the case of anisotropic polarizability, the dependence of the Casimir-Polder potential on the orientation of the polarizability tensor principal axes also leads to a moment of force acting on the particle. (orig.)
R., Sini; Varghese, Nijo; Kuriakose, V. C.
2008-01-01
Dirac equation for a general black hole metric having a cosmic string is derived. The quasi-normal mode frequencies for Schwarzschild, RN extremal, SdS and near extremal SdS black hole space-times with cosmic string perturbed by a massless Dirac field are obtained using WKB approximation and found that in all these cases, decay is less in black holes having cosmic string compared to black holes with out string.
A simple model for the evolution of a non-Abelian cosmic string network
Cella, G
2015-01-01
In this paper we present the results of numerical simulations intended to study the behavior of non-Abelian cosmic strings networks. In particular we are interested in discussing the variations in the asymptotic behavior of the system as we variate the number of generators for the topological defects. A simple model which should generate cosmic strings is presented and its lattice discretization is discussed. The evolution of the generated cosmic string networks is then studied for different values for the number of generators for the topological defects. Scaling solution appears to be approached in most cases and we present an argument to justify the lack of scaling for the residual cases.
The Implications of the COBE-DMR Results for Cosmic Strings
Bennett, David P.; Stebbins, Albert; Bouchet, Francois R.
1992-01-01
We compare the anisotropies in the cosmic microwave background radiation measured by the COBE experiment to the predictions of cosmic strings. We use an analytic model for the $\\Delta T/T$ power spectrum that is based on our previous numerical simulations to show that the COBE results imply a value for the string mass per unit length, $\\mu$ under the assumption that cosmic strings are the source of the measured anisotropy. We find $G\\mu = 1.5\\pm 0.5 \\times 10^{-6}$ which is consistent with th...
Evading the pulsar constraints on the cosmic string tension in supergravity inflation
Energy Technology Data Exchange (ETDEWEB)
Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Miyamoto, Yuhei [Tokyo Univ. (Japan). Dept. of Physics; Tokyo Univ. (JP). Research Center for the Early Universe (RESCEU); Yokoyama, Jun' ichi [Tokyo Univ. (JP). Research Center for the Early Universe (RESCEU); Tokyo Univ., Kashiwa, Chiba (JP). Inst. for the Physics and Mathematics of the Universe (IPMU)
2012-04-15
The cosmic string is a useful probe of the early Universe and may give us a clue to physics at high energy scales where any artificial particle accelerators cannot reach. Although one of the most promising tools is the cosmic microwave background, the constraint from gravitational waves is becoming so stringent that one may not hope to detect its signatures in the cosmic microwave background. In this paper, we construct a scenario that contains cosmic strings observable in the cosmic microwave background while evading the constraint imposed by the recent pulsar timing data. We argue that cosmic strings with relatively large tension are allowed by delaying the onset of the scaling regime. We also show that this scenario is naturally realized in the context of chaotic inflation in supergravity, where the phase transition is governed by the Hubble induced mass.
The Battle of the Bulge: Decay of the Thin, False Cosmic String
Lee, Bum-Hoon; MacKenzie, Richard; Paranjape, M B; Yajnik, U A; Yeom, Dong-han
2013-01-01
We consider the decay of cosmic strings that are trapped in the false vacuum in a theory of scalar electrodynamics in 3+1 dimensions. We restrict our analysis to the case of thin-walled cosmic strings which occur when large magnetic flux trapped inside the string. Thus the string looks like a tube of fixed radius, at which it is classically stable. The core of the string contains magnetic flux in the true vacuum, while outside the string, separated by a thin wall, is the false vacuum. The string decays by tunnelling to a configuration which is represented by a bulge, where the region of true vacuum within, is ostensibly enlarged. The bulge can be described as the meeting, of a kink soliton anti-soliton pair, along the length of the string. It can be described as a bulge appearing in the initial string, starting from the string of small, classically stable radius, expanding to a fat string of large, classically unstable (to expansion) radius and then returning back to the string of small radius along its lengt...
Searching for Cosmic Strings in CMB Anisotropy Maps using Wavelets and Curvelets
Hergt, Lukas; Brandenberger, Robert; Kacprzak, Tomasz; Refregier, Alexandre
2016-01-01
We use wavelet and curvelet transforms to extract signals of cosmic strings from cosmic microwave background (CMB) temperature anisotropy maps, and to study the limits on the cosmic string tension which various ongoing CMB temperature anisotropy experiments will be able to achieve. We construct sky maps with size and angular resolution corresponding to various experiments. These maps contain the signals of a scaling solution of long string segments with a given string tension $G \\mu$, the contribution of the dominant Gaussian primordial cosmological fluctuations, and pixel by pixel white noise with an amplitude corresponding to the instrumental noise of the various experiments. In the case that we include white noise, we find that the curvelets are more powerful than wavelets. For maps with Planck specification, we obtain bounds on the string tension comparable to what was obtained by the Planck collaboration. Experiments with better angular resolution such as the South Pole Telescope third generation (SPT-3G...
The bound state Aharonov-Bohm effect around a cosmic string revisited
Filgueiras, C.; Moraes, Fernando
2005-01-01
In this article we observe that the self-adjoint extension of the Hamiltonian of a particle moving around a shielded cosmic string gives rise to a gravitational analogue of the bound state Aharonov-Bohm effect.
Absorption/Scattering of Massless Dirac Wave from Black Hole Spacetimes with Cosmic String
International Nuclear Information System (INIS)
In this paper we investigate the scattering of massless Dirac wave from several different black hole spacetimes (i.e. the Schwarzschild black hole, the RN extremal black hole, the Schwarzschild de Sitter black hole, and the extremal Schwarzschild de Sitter black hole) which are influenced by the cosmic string, respectively. All these cases show us that the total absorption cross sections oscillate around the geometric-optical limit and decrease with linear mass density μ of the cosmic string. All of the total scattering cross sections exhibit that the main scattering angle becomes narrower for the high partial frequency wave. Due to the influence of cosmic string, the glory peak becomes wider for larger values of linear mass density μ of the cosmic string. (general)
The stochastic background from cosmic (super)strings: popcorn and (Gaussian) continuous regimes
Regimbau, Tania; Giampanis, Stefanos; Siemens, Xavier; Mandic, Vuk
2011-01-01
In the era of the next generation of gravitational wave experiments a stochastic background from cusps of cosmic (super)strings is expected to be probed and, if not detected, to be significantly constrained. A popcorn-like background can be, for part of the parameter space, as pronounced as the (Gaussian) continuous contribution from unresolved sources that overlap in frequency and time. We study both contributions from unresolved cosmic string cusps over a range of frequencies relevant to gr...
The effect of extra dimensions on gravity wave bursts from cosmic string cusps
International Nuclear Information System (INIS)
We explore the kinematical effect of having extra dimensions on the gravitational wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravitational wave burst, taking into account these two factors, and find a potentially significant damping on the gravitational waves of the strings
Warped Self-Gravitating U(1) Gauge Cosmic Strings in 5D
Slagter, R.J.; Masselink, D.
2012-01-01
We present the "classical" Nielsen-Olesen vortex solution on a warped five dimensional space time, where we solved the effective four-dimensional equations from the five-dimensional equations together with the junction and boundary conditions. Four dimensional cosmic strings show some serious problems concerning the mechanism of string smoothing related to the string mass per unit length, $G\\mu \\leq 10^{-6}$. Moreover, there is no observational evidence of axially symmetric lensing effect cau...
Evading the pulsar constraints on the cosmic string tension in supergravity inflation
International Nuclear Information System (INIS)
The cosmic string is a useful probe of the early Universe and may give us a clue to physics at high energy scales which particle accelerators cannot reach. Although the most promising tool to observe it is the cosmic microwave background (CMB), the constraint from gravitational waves is becoming so stringent that detecting its signatures in CMB may be impossible. In this paper, we construct a scenario that contains cosmic strings observable in the cosmic microwave background while evading the constraint imposed by the recent pulsar timing data. We argue that cosmic strings with relatively large tension are allowed by diluting loops contributing to the relevant frequency range of the gravitational wave background. We also present a particle physics model to realize such dilution in the context of chaotic inflation in supergravity, where the phase transition occurs during inflation due to the time-dependence of the Hubble induced mass
The gravitational wave spectrum from cosmological B-L breaking
International Nuclear Information System (INIS)
Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying ΩGWh2 ∼ 10−13–10−8, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, BBO and DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking
The gravitational wave spectrum from cosmological B-L breaking
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.; Domcke, V.; Kamada, K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Schmitz, K. [Tokyo Univ., Kashiwa (Japan). Kavli IPMU (WPI)
2013-05-15
Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying {Omega}{sub GW}h{sup 2}{proportional_to}10{sup -13}-10{sup -8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO and BBO/DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.
The gravitational wave spectrum from cosmological B-L breaking
Energy Technology Data Exchange (ETDEWEB)
Buchmüller, W.; Domcke, V.; Kamada, K. [Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg (Germany); Schmitz, K., E-mail: buchmuwi@mail.desy.de, E-mail: valerie.domcke@desy.de, E-mail: kohei.kamada@desy.de, E-mail: kai.schmitz@ipmu.jp [Kavli IPMU (WPI), University of Tokyo, Kashiwa 277-8583 (Japan)
2013-10-01
Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying Ω{sub GW}h{sup 2} ∼ 10{sup −13}–10{sup −8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, BBO and DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.
Light deflection with torsion effects caused by a spinning cosmic string
Jusufi, Kimet
2016-06-01
Using a new geometrical method introduced by Werner, we find the deflection angle in the weak limit approximation by a spinning cosmic string in the context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the optical geometry and derive the leading terms of the deflection angle in the equatorial plane. Calculation shows that light deflection is affected by the intrinsic spin of the cosmic string and torsion.
Light Deflection with Torsion Effects Caused by a Spinning Cosmic String
Jusufi, Kimet
2016-01-01
Using a new geometrical method introduced by Werner, we find the deflection angle in the weak limit approximation by a spinning cosmic string in the context of the Einstein-Cartan (EC) theory of gravity. We begin by adopting the String-Randers optical metric, then we apply the Gauss-Bonnet theorem to the optical geometry and derive the leading terms of the deflection angle in the equatorial plane. Calculations shows that light deflection is affected by the intrinsic spin of the cosmic string and torsion.
Search for cosmic strings in the Great Observatories Origins Deep Survey
International Nuclear Information System (INIS)
We search Hubble Space Telescope Treasury Program images collected as part of the Great Observatories Origins Deep Survey for pairs of galaxies consistent with the gravitational lensing signature of a cosmic string. Our technique includes estimates of the efficiency for finding the lensed galaxy pair. In the north (south) survey field we find no evidence out to a redshift of greater than 0.5 (0.3) for cosmic strings to a mass per unit length limit of Gμ/c2-7 at 95% confidence limits (C.L.). In the combined 314.9 arcmin2 of the north and south survey fields this corresponds to a global limit on Ωstrings2 is more than an order of magnitude lower than searches for individual strings in cosmic microwave background (CMB) data. Our limit is higher than other CMB and gravitational wave searches, however, we note that it is less model dependent than these other searches
Gravitational-Wave Stochastic Background from Kinks and Cusps on Cosmic Strings
Olmez, S; Siemens, X
2010-01-01
We compute the contribution of kinks on cosmic string loops to stochastic background of gravitational waves (SBGW).We find that kinks contribute at the same order as cusps to the SBGW.We discuss the accessibility of the total background due to kinks as well as cusps to current and planned gravitational wave detectors, as well as to the big bang nucleosynthesis (BBN), the cosmic microwave background (CMB), and pulsar timing constraints. As in the case of cusps, we find that current data from interferometric gravitational wave detectors, such as LIGO, are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds.
Gravitational waves from kinks on infinite cosmic strings
Kawasaki, Masahiro; Miyamoto, Koichi; Nakayama, Kazunori(Department of Physics, University of Tokyo, 7-3-1 Bunkyo-ku, Hongo, Tokyo 113-0033, Japan)
2010-01-01
Gravitational waves emitted by kinks on infinite strings are investigated using detailed estimations of the kink distribution on infinite strings. We find that gravitational waves from kinks can be detected by future pulsar timing experiments such as SKA for an appropriate value of the the string tension, if the typical size of string loops is much smaller than the horizon at their formation. Moreover, the gravitational wave spectrum depends on the thermal history of the Universe and hence it...
Planck 2013 results. XXV. Searches for cosmic strings and other topological defects
Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Battaner, E.; Battye, R.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Ensslin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Hansen, F.K.; Hanson, D.; Harrison, D.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lawrence, C.R.; Leahy, J.P.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; McEwen, J.D.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Naselsky, P.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Peiris, H.V.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Rath, C.; Rebolo, R.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ringeval, C.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Varis, J.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; Yvon, D.; Zacchei, A.; Zonca, A.
2014-01-01
Planck data have been used to provide stringent new constraints on cosmic strings and other defects. We describe forecasts of the CMB power spectrum induced by cosmic strings, calculating these from network models and simulations using line-of-sight Boltzmann solvers. We have studied Nambu-Goto cosmic strings, as well as field theory strings for which radiative effects are important, thus spanning the range of theoretical uncertainty in strings models. We have added the angular power spectrum from strings to that for a simple adiabatic model, with the extra fraction defined as $f_{10}$ at multipole $\\ell=10$. This parameter has been added to the standard six parameter fit using COSMOMC with flat priors. For the Nambu-Goto string model, we have obtained a constraint on the string tension of $G\\mu/c^2 < 1.5 x 10^{-7}$ and $f_{10} < 0.015$ at 95% confidence that can be improved to $G\\mu/c^2 < 1.3 x 10^{-7}$ and $f_{10} < 0.010$ on inclusion of high-$\\ell$ CMB data. For the abelian-Higgs field theory ...
Planck 2013 results. XXV. Searches for cosmic strings and other topological defects
DEFF Research Database (Denmark)
Planck Collaboration,; Ade, P. A. R.; Aghanim, N.;
2013-01-01
-Goto cosmic strings, as well as field theory strings for which radiative effects are important, thus spanning the range of theoretical uncertainty in strings models. We have added the angular power spectrum from strings to that for a simple adiabatic model, with the extra fraction defined as $f_{10}$ at......Planck data have been used to provide stringent new constraints on cosmic strings and other defects. We describe forecasts of the CMB power spectrum induced by cosmic strings, calculating these from network models and simulations using line-of-sight Boltzmann solvers. We have studied Nambu...... multipole $\\ell=10$. This parameter has been added to the standard six parameter fit using COSMOMC with flat priors. For the Nambu-Goto string model, we have obtained a constraint on the string tension of $G\\mu/c^2 <1.5 x 10^{-7}$ and $f_{10} <0.015$ at 95% confidence that can be improved to $G\\mu/c^2 <1...
Spontaneous excitation of a static atom in a thermal bath in cosmic string spacetime
Cai, Huabing; Zhou, Wenting
2015-01-01
We study the average rate of change of energy for a static atom immersed in a thermal bath of electromagnetic radiation in the cosmic string spacetime and separately calculate the contributions of thermal fluctuations and radiation reaction. We find that the transition rates are crucially dependent on the atom-string distance and polarization of the atom and they in general oscillate as the atom-string distance varies. Moreover, the atomic transition rates in the cosmic string spacetime can be larger or smaller than those in Minkowski spacetime contingent upon the atomic polarization and position. In particular, when located on the string, ground-state atoms can make a transition to excited states only if they are polarizable parallel to the string, whereas ground state atoms polarizable only perpendicular to the string are stable as if they were in a vacuum, even if they are immersed in a thermal bath. Our results suggest that the influence of a cosmic string is very similar to that of a reflecting boundary ...
High redshift signatures in the 21 cm forest due to cosmic string wakes
International Nuclear Information System (INIS)
Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ''21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (z∼>10), even if the string tension is below the current upper bound, Gμ < 1.5 × 10−7. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with Gμ ≈ 7.5 × 10−8 for the single frequency band case and 4.0 × 10−8 for the multi-frequency band case
Spontaneous excitation of a uniformly accelerated atom in the cosmic string spacetime
Zhou, Wenting; Yu, Hongwei
2016-04-01
We study, in the cosmic string spacetime, the average rate of change of energy for an atom coupled to massless scalar fields and uniformly accelerated in a direction parallel to the string in vacuum. We find that both the noninertial motion and the nontrivial global spacetime topology affect the atomic transition rates, so an accelerated atom (an Unruh detector) does feel the string contrary to claims in the literature. We demonstrate that the equivalence between the effect of uniform acceleration and that of thermal radiation on the transition rates of the atom, which is valid in the Minkowski spacetime, holds only on the string.
Predicted constraints on cosmic string tension from Planck and future CMB polarization measurements
International Nuclear Information System (INIS)
We perform a Fisher matrix calculation of the predicted uncertainties on estimates of the cosmic string tension Gμ from upcoming observational data (namely, cosmic microwave background power spectra from the Planck satellite and an idealized future polarization experiment). We employ simulations that are more general than others commonly used in the literature, leaving the mean velocity of strings, correlation length of the string network, and wiggliness (which parametrizes smaller-scale structure along the strings) as free parameters that can be observationally measured. In a new code, StringFast, we implement a method for efficient computation of the Cl spectra induced by a network of strings, which is fast enough to be used in Markov Chain Monte Carlo analyses of future data. Performing a calculation with the string parameters left free results in projected constraints on Gμ that are larger than those obtained by fixing their values a priori, typically by a factor of ∼2-7. We also find that, if Gμ is equal to the current observational maximum, Planck will be able to make a confident detection of strings. However, if Gμ is 2 orders of magnitude smaller, even a perfect, lensing-free measurement of polarization power spectra will not be able to detect a nonzero string tension at better than 2σ confidence.
Fermionic current induced by magnetic flux in compactified cosmic string spacetime
International Nuclear Information System (INIS)
In this paper, we investigate the fermionic current densities induced by a magnetic flux running along the idealized cosmic string in a four-dimensional spacetime, admitting that the coordinate along the string's axis is compactified. In order to develop this investigation we construct the complete set of fermionic mode functions obeying a general quasiperiodicity condition along the compactified dimension. The vacuum expectation value of the azimuthal current density is 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. For the first part we provide a closed expression which includes various special cases previously discussed in the literature. The second part is an odd periodic function of the magnetic flux along the string axis with the period equal to the flux quantum and it is an even function of the magnetic flux enclosed by the string axis. The compactification of the cosmic string axis in combination with the quasiperiodicity condition leads to the nonzero axial current density. The latter is an even periodic function of the magnetic flux along the string axis and an odd periodic function of the magnetic flux enclosed by the string axis. The axial current density vanishes for untwisted and twisted fields in the absence of the magnetic flux enclosed by the string axis. The asymptotic behavior of the vacuum fermionic current is investigated near the string and at large distances from it. In particular, the topological part of the azimuthal current and the axial current are finite on the string's axis. (orig.)
Geodesic motion in the space-time of cosmic strings interacting via magnetic fields
Hartmann, Betti
2012-01-01
We study the geodesic motion of test particles in the space-time of two Abelian-Higgs strings interacting via their magnetic fields. These bound states of cosmic strings constitute a field theoretical realization of p-q-strings which are predicted by inflationary models rooted in String Theory, e.g. brane inflation. In contrast to previously studied models describing p-q-strings our model possesses a Bogomolnyi-Prasad-Sommerfield (BPS) limit. If cosmic strings exist it would be exciting to detect them by direct observation. We propose that this can be done by the observation of test particle motion in the space-time of these objects. In order to be able to make predictions we have to solve the field equations describing the configuration as well as the geodesic equation numerically. The geodesics can then be classified according to the test particle's energy, angular momentum and momentum along the string axis. We find that the interaction of two Abelian-Higgs strings can lead to the existence of bound orbits...
Vacuumless cosmic strings in Brans-Dicke theory
Sen, A. A.
1999-01-01
The gravitational fields of vacuumless global and gauge strings have been studied in Brans-Dicke theory under the weak field assumption of the field equations. It has been shown that both global and gauge string can have repulsive as well as attractive gravitational effect in Brans-Dicke theory which is not so in General Relativity.
Cosmic strings with twisted magnetic flux lines and wound-strings in extra dimensions
International Nuclear Information System (INIS)
We consider a generalization of the Nielsen-Olesen ansatz, in the abelian-Higgs model, which describes strings with twisted magnetic flux lines in the vortex core. The solution does not possess cylindrical symmetry, which leads to the existence of components of conserved momentum, both around the core-axis and along the length of the string. In addition, we consider a model of F-strings with rotating, geodesic windings in the compact space of the Klebanov-Strassler geometry and determine matching conditions which ensure energy and momentum conservation when loops chop off from the long-string network. We find that the expressions for the constants of motion, which determine the macroscopic string dynamics, can be made to coincide with those for the twisted flux line string, suggesting that extra-dimensional effects for F-strings may be mimicked by field-theoretic structure in topological defects
Gravitational Waves from Light Cosmic Strings: Backgrounds and Bursts with Large Loops
Hogan, Craig J.
2006-01-01
The mean spectrum and burst statistics of gravitational waves produced by a cosmological population of cosmic string loops are estimated using analytic approximations, calibrated with earlier simulations. Formulas are derived showing the dependence of observables on the string tension, in the regime where newly-formed loops are relatively large, not very much smaller than the horizon. Large loops form earlier, are more abundant, and generate a more intense stochastic background and more frequ...
Fermionic vacuum polarization by a flat boundary in cosmic string spacetime
International Nuclear Information System (INIS)
In this paper, we investigate the fermionic condensate and the renormalized vacuum expectation value (VEV) of the energy–momentum tensor for a massive fermionic field induced by a flat boundary in the cosmic string spacetime. In this analysis, we assume that the field operator obeys MIT bag boundary condition on the boundary. We explicitly decompose the VEVs into the boundary-free and boundary-induced parts. General formulas are provided for both parts which are valid for any value of the parameter associated with the cosmic string. For a massless field, the boundary-free part in the fermionic condensate and the boundary-induced part in the energy–momentum tensor vanish. For a massive field, the radial stress is equal to the energy density for both boundary-free and boundary-induced parts. The boundary-induced part in the stress along the axis of the cosmic string vanishes. The total energy density is negative everywhere, whereas the effective pressure along the azimuthal direction is positive near the boundary and negative near the cosmic string. We show that for points away from the boundary, the boundary-induced parts in the fermionic condensate and in the VEV of the energy–momentum tensor vanish on the string. (paper)
Battle of the bulge: Decay of the thin, false cosmic string
Lee, Bum-Hoon; Lee, Wonwoo; MacKenzie, Richard; Paranjape, M. B.; Yajnik, U. A.; Yeom, Dong-han
2013-11-01
We consider the decay of cosmic strings that are trapped in the false vacuum in a theory of scalar electrodynamics in 3+1 dimensions. This paper is the 3+1-dimensional generalization of the 2+1-dimensional decay of false vortices which we have recently completed . We restrict our analysis to the case of thin-walled cosmic strings which occur when large magnetic flux is trapped inside the string. Thus the string looks like a tube of fixed radius, at which it is classically stable. The core of the string contains magnetic flux in the true vacuum, while outside the string, separated by a thin wall, is the false vacuum. The string decays by tunneling to a configuration which is represented by a bulge, where the region of true vacuum within is ostensibly enlarged. The bulge can be described as the meeting of a kink soliton-antisoliton pair along the length of the string. It can be described as a bulge appearing in the initial string, starting from the string of small, classically stable radius, expanding to a fat string of large, classically unstable (to expansion) radius and then returning back to the string of small radius along its length. This configuration is the bounce point of a corresponding O(2) symmetric instanton, which we can determine numerically. Once the bulge appears it explodes in real time. The paired soliton and antisoliton recede from each other along the length of the string with a velocity that quickly approaches the speed of light, leaving behind a fat tube. At the same time the radius of the fat tube that is being formed expands (transversely) as it is no longer classically stable, converting false vacuum to the true vacuum with ever-diluting magnetic field within. The rate of this expansion is determined by the energy difference between the true vacuum and the false vacuum. Our analysis could be applied to a network of cosmic strings formed in the very early Universe or vortex lines in a superheated superconductor.
Akcay, Ali Riza
1999-01-01
This paper describes that the superconducting cosmic strings can be connected to an electrically charged black hole, and can be considerd as the hair of black hole. What the no-hair theorems show is that a large amount of information is lost when a body collapses to form a black hole. In addition, the no-hair theorem has not been proved for the Yang-Mills field. This paper proves and claims that the superconducting cosmic strings can be connected to an electrically charged hole when the curre...
Implications of cosmic string-induced density ﬂuctuations at the quark–hadron transition
Indian Academy of Sciences (India)
Biswanath Layek; Soma Sanyal; Ajit M Srivastava
2003-11-01
We show that cosmic strings moving through the plasma at the time of a ﬁrst-order quark–hadron transition in the early universe generate baryon inhomogeneities, which can survive till the nucleosynthesis epoch. We ﬁnd out how these inhomogeneities actually affect the calculated values of the light element abundances. Recently a wealth of observational data from various experiments have helped to reduce the uncertainties in the values of these abundances. Using these we show that it is possible to derive constraints in the presence of cosmic strings during the quark–hadron transition.
Baryon inhomogeneities due to cosmic string wakes at the quark–hadron transition
Indian Academy of Sciences (India)
Biswanath Layek; Soma Sanyal; Ajit M Srivastava
2003-05-01
Baryon inhomogeneities generated during the quark–hadron transition may alter the abundances of light elements if they persist up to the time of nucleosynthesis. These inhomogeneities survive up to the nucleosynthesis epoch if they are separated by a distance of at least a few metres. In this work we present a model where large sheets of these inhomogeneities separated by a distance of a few km are formed by cosmic string wakes during the quark–hadron transition. The effect of these sheets on nucleosynthesis will also put constraints on the various cosmic string parameters.
Polynomial solutions of the field equations for cosmic strings coupled to the einstein equations
International Nuclear Information System (INIS)
A cosmic string described by an interaction Lagrangian and including a U(1) gauge vector field, minimally coupled to a scalar field was considered. This Lagrangian includes also a gravitation interacting scalar term. The field equations have been obtained from the above Lagrangian, these equations were coupled to Einstein's equations. Such a system of equations has been solved numerically and polynomial expansions derived for the fields which describe the string. With the above solutions the second order corrections to the angular deficit, produced by the string was determined. (author)
Cosmic strings in hidden sectors: 1. Radiation of standard model particles
Energy Technology Data Exchange (ETDEWEB)
Long, Andrew J.; Hyde, Jeffrey M.; Vachaspati, Tanmay, E-mail: andrewjlong@asu.edu, E-mail: jmhyde@asu.edu, E-mail: tvachasp@asu.edu [Physics Department, Arizona State University, Tempe, Arizona 85287 (United States)
2014-09-01
In hidden sector models with an extra U(1) gauge group, new fields can interact with the Standard Model only through gauge kinetic mixing and the Higgs portal. After the U(1) is spontaneously broken, these interactions couple the resultant cosmic strings to Standard Model particles. We calculate the spectrum of radiation emitted by these ''dark strings'' in the form of Higgs bosons, Z bosons, and Standard Model fermions assuming that string tension is above the TeV scale. We also calculate the scattering cross sections of Standard Model fermions on dark strings due to the Aharonov-Bohm interaction. These radiation and scattering calculations will be applied in a subsequent paper to study the cosmological evolution and observational signatures of dark strings.
Cosmic Strings in Hidden Sectors: 1. Radiation of Standard Model Particles
Long, Andrew J; Vachaspati, Tanmay
2014-01-01
In hidden sector models with an extra U(1) gauge group, new fields can interact with the Standard Model only through gauge kinetic mixing and the Higgs portal. After the U(1) is spontaneously broken, these interactions couple the resultant cosmic strings to Standard Model particles. We calculate the spectrum of radiation emitted by these "dark strings" in the form of Higgs bosons, Z bosons, and Standard Model fermions assuming that string tension is above the TeV scale. We also calculate the scattering cross sections of Standard Model fermions on dark strings due to the Aharonov-Bohm interaction. These radiation and scattering calculations will be applied in a subsequent paper to study the cosmological evolution and observational signatures of dark strings.
Cosmic D- and DF-strings from D3Dbar3: Black Strings and BPS Limit
Kim, Taekyung; Kim, Yoonbai; Kyae, Bumseok; Lee, Jungjai
2006-01-01
We study D- and DF-strings in a D3${\\bar {\\rm D}}3$ system by using Dirac-Born-Infeld type action. In the presence of an electric flux from the transverse direction, we discuss gravitating thick D-string solutions of a spatial manifold, ${\\rm S}^{2}\\times {\\rm R}^{1}$, in which straight D-strings stretched along the R${}^{1}$ direction are attached to the south and north poles of the two-sphere. There is a horizon along its equator, which means the structure of black strings is formed. We als...
Universal Reconnection of Non-Abelian Cosmic Strings
Eto, M; Marmorini, G; Nitta, M; Ohashi, K; Vinci, W; Eto, Minoru; Hashimoto, Koji; Marmorini, Giacomo; Nitta, Muneto; Ohashi, Keisuke; Vinci, Walter
2006-01-01
We show that local/semilocal strings in Abelian/non-Abelian gauge theories with critical couplings always reconnect classically in collision, by using moduli space approximation. The moduli matrix formalism explicitly identifies a well-defined set of the vortex moduli parameters. Our analysis of generic geodesic motion in terms of those shows right-angle scattering in head-on collision of two vortices, which is known to give the reconnection of the strings.
Cosmic strings in f(R,L{sub m}) gravity
Energy Technology Data Exchange (ETDEWEB)
Harko, Tiberiu, E-mail: t.harko@ucl.ac.uk [Department of Mathematics, University College London, Gower Street, WC1E 6BT, London (United Kingdom); Lake, Matthew J., E-mail: matthewj@nu.ac.th [The Institute for Fundamental Study, “The Tah Poe Academia Institute”, Naresuan University, 65000, Phitsanulok (Thailand); Thailand Center of Excellence in Physics, Ministry of Education, 10400, Bangkok (Thailand)
2015-02-07
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.
Cosmic strings in f(R,Lm) gravity
International Nuclear Information System (INIS)
We consider Kasner-type static, cylindrically symmetric interior string solutions in the f(R,Lm) theory of modified gravity. The physical properties of the string are described by an anisotropic energy-momentum tensor satisfying the condition Ttt=Tzz; 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,Lm) 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
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.)
Fermionic vacuum polarization by a cosmic string in anti-de Sitter spacetime
International Nuclear Information System (INIS)
In this paper, we investigate the fermionic condensate (FC) and the vacuum expectation value (VEV) of the energy–momentum tensor, associated with a massive fermionic field, induced by the presence of a cosmic string in the anti-de Sitter (AdS) spacetime. In order to develop this analysis we construct the complete set of normalized eigenfunctions in the corresponding spacetime. We consider a special case of boundary conditions on the AdS boundary, when the MIT bag boundary condition is imposed on the field operator at a finite distance from the boundary, which is then taken to zero. The FC and the VEV of the energy–momentum tensor are decomposed into the pure AdS and string-induced parts. Because the analysis of one-loop quantum effects in the AdS spacetime has been developed in the literature, here we are mainly interested to investigate the influence of the cosmic string on the VEVs. The string-induced part in the VEV of the energy–momentum tensor is diagonal and the axial and radial stresses are equal to the energy density. For points near the string, the effects of the curvature are subdominant and to leading order, the VEVs coincide with the corresponding VEVs for the cosmic string in the Minkowski bulk. At large proper distances from the string, the decay of the VEVs show a power-law dependence of the distance for both massless and massive fields. This is in contrast to the case of the Minkowski bulk where, for a massive field, the string-induced parts decay exponentially. (paper)
Cosmic D- and DF-strings from D3Dbar3: Black Strings and BPS Bound
Kim, T; Kyae, B; Lee, J; Kim, Taekyung; Kim, Yoonbai; Kyae, Bumseok; Lee, Jungjai
2006-01-01
We study D- and DF-strings from D3${\\bar {\\rm D}}3$ in the context of Dirac-Born-Infeld type effective field theory. In the presence of an electric flux from a transverse direction, gravitating thick D-string solutions form a spatial manifold, ${\\rm S}^{2}\\times {\\rm R}^{1}$, and straight D-strings stretched along the R${}^{1}$ direction are located at the south and north poles of the two-sphere. There is a horizon along its equator and then the structure of black strings is supported. We also discuss systematic derivation of the BPS bounds for thin parallel D- and DF-strings in both flat and curved spacetime. The BPS sum rule is obtained for arbitrarily-separated multi-string configuration under a Gaussian type tachyon potential and, at the site of each thin BPS D(F)-string, the pressure does not vanish but is finite. For the conical geometry induced by thin BPS D- and DF-strings, we find that there exists maximum deficit angle $\\pi$.
Capture and critical scattering of a long cosmic string by a rotating black hole
International Nuclear Information System (INIS)
The capture of a straight, infinitely long cosmic string by a rotating black hole with rotation parameter a is considered. We assume that a string is moving with velocity v and that initially the string is parallel to the axis of rotation of the black hole and has the impact parameter b. The string can be either scattered or captured by the black hole. We demonstrate that there exists a critical value of the impact parameter bc(v, a) which separates these two regimes. Using numerical simulations we obtain the critical impact parameter curve for different values of the rotation parameter a. We show that for the prograde motion of the string this curve lies below the curve for the retrograde motion. Moreover, for ultrarelativistic strings moving in the prograde direction and nearly extremal black holes the critical impact parameter curve is found to be a multiply valued function of v. We obtain real time profiles of the scattered strings in the regime close to the critical. We also study critical scattering and capture of strings by the rotating black hole in the relativistic and ultrarelativistic regimes and especially such relativistic effects as coil formation and wrapping effect
Casimir-Polder potential for a metallic cylinder in cosmic string spacetime
International Nuclear Information System (INIS)
Casimir-Polder potential is investigated for a polarizable microparticle in the geometry of a straight cosmic string with a metallic cylindrical shell. The electromagnetic field Green tensor is evaluated on the imaginary frequency axis. The expressions for the Casimir-Polder potential is derived in the general case of anisotropic polarizability for the both interior and exterior regions of the shell. The potential is decomposed into pure string and shell-induced parts. The latter dominates for points near the shell, whereas the pure string part is dominant near the string and at large distances from the shell. For the isotropic case and in the region inside the shell the both pure string and shell-induced parts in the Casimir-Polder force are repulsive with respect to the string. In the exterior region the shell-induced part of the force is directed toward the cylinder whereas the pure string part remains repulsive with respect to the string. At large distances from the shell the total force is repulsive.
The vacuum expectation value of the spinor massive field in the cosmic string spacetime
Energy Technology Data Exchange (ETDEWEB)
Bezerra, Valdir B; Khusnutdinov, Nail R [Departamento de Fisica, Universidade Federal da ParaIba, Caixa Postal 5008, CEP 58051-970 Joao Pessoa, Pb (Brazil)
2006-05-21
We find the contribution to the vacuum expectation value of the energy-momentum tensor of a massive Dirac field due to the conical geometry of the cosmic string spacetime. The heat kernel and heat kernel expansion for the squared Dirac operator in this background are also considered and the first three coefficients are found in an explicit form.
Hot scalar radiation around a cosmic string setting bounds on $\\xi$
Moreira, E S
2016-01-01
In this work, by investigating the low temperature behaviour of a scalar field around a cosmic string, and assuming stable thermodynamic equilibrium, it is shown that the coupling parameter of the field with curvature must be restricted to a certain range of values whose bounds are determined by the deficit angle of the associated conical geometry.
The bound-state Aharonov-Bohm effect around a cosmic string revisited
International Nuclear Information System (INIS)
In this Letter we observe that the self-adjoint extension of the Hamiltonian of a particle moving around a cosmic string gives rise to a gravitational analogue of the bound-state Aharonov-Bohm effect without the need of confining walls
A discussion on supersymmetric cosmic strings with gauge-field mixing
International Nuclear Information System (INIS)
Following a stream of investigation on supersymmetric gauge theories with cosmic-string solutions, we contemplate the possibility of building up a D and F term cosmic string by means of a gauge-field mixing in connection with a U(1)xU(1)' symmetry. The spontaneous break of both gauge symmetry and supersymmetry are thoroughly analysed and the fermion zero modes are worked out. The role of the gauge-field mixing parameter is elucidated in connection with the string configuration that comes out. As an application of the model presented here, we propose the possibility that the supersymmetric cosmic-string yields the production of fermionic charge carriers that may eject, at their late stages, particles that subsequently decay to produce cosmic rays of ultra-high energy. In our work, it turns out that massive supersymmetric fermionic partners may be produced for a SUSY breaking scale in the range 1011-1013 GeV, which is compatible with the phenomenology of a gravitino mass at the TeV scale. We also determine the range of the gauge-field mixing parameter, α, in connection with the mass scales of the present model
The stochastic background from cosmic (super)strings: popcorn and (Gaussian) continuous regimes
Regimbau, Tania; Siemens, Xavier; Mandic, Vuk
2011-01-01
In the era of the next generation of gravitational wave experiments a stochastic background from cusps of cosmic (super)strings is expected to be probed and, if not detected, to be significantly constrained. A popcorn-like background can be, for part of the parameter space, as pronounced as the (Gaussian) continuous contribution from unresolved sources that overlap in frequency and time. We study both contributions from unresolved cosmic string cusps over a range of frequencies relevant to ground based interferometers, such as LIGO/Virgo second generation (AdLV) and Einstein Telescope (ET) third generation detectors, the space antenna LISA and Pulsar Timing Arrays (PTA). We compute the sensitivity (at $2 \\sigma$ level) in the parameter space for AdLV, ET, LISA and PTA. We conclude that the popcorn regime is complementary to the continuous background. Its detection could therefore enhance confidence in a stochastic background detection and possibly help determine fundamental string parameters such as the strin...
Improved calculation of the gravitational wave spectrum from kinks on infinite cosmic strings
Matsui, Yuka; Nitta, Daisuke; Kuroyanagi, Sachiko
2016-01-01
Gravitational wave observations provide unique opportunities to search for cosmic strings. One of the strongest sources of gravitational waves is discontinuities of cosmic strings, called kinks, which are generated at points of intersection. Kinks on infinite strings are known to generate a gravitational wave background over a wide range of frequencies. In this paper, we calculate the spectrum of the gravitational wave background by numerically solving the evolution equation for the distribution function of the kink sharpness. We find that the number of kinks for small sharpness is larger than the analytical estimate used in a previous work, which makes a difference in the spectral shape. Our numerical approach also helps to avoid the use of analytic approximations, and enables us to make a more precise prediction on the spectral amplitude for future gravitational wave experiments.
CMB power spectra from cosmic strings: predictions for the Planck satellite and beyond
Bevis, Neil; Kunz, Martin; Urrestilla, Jon
2010-01-01
We present a significant improvement over our previous calculations of the cosmic string contribution to cosmic microwave background (CMB) power spectra, with particular focus on sub-WMAP angular scales. These smaller scales are relevant for the now-operational Planck satellite and additional sub-orbital CMB projects that have even finer resolutions. We employ larger Abelian Higgs string simulations than before and we additionally model and extrapolate the statistical measures from our simulations to smaller length scales. We then use an efficient means of including the extrapolations into our Einstein-Boltzmann calculations in order to yield accurate results over the multipole range 2 3000 in the case of the temperature power spectrum, which then allows cautious extrapolation to even smaller scales. We find that a string contribution to the temperature power spectrum making up 10% of power at l=10 would be larger than the Silk-damped primary adiabatic contribution for l > 3500. Astrophysical contributions s...
Finite temperature bosonic charge and current densities in compactified cosmic string spacetime
Mohammadi, Azadeh
2015-01-01
In this paper we study the expectation values of the induced charge and current densities for a massive bosonic field with nonzero chemical potential in the geometry of a higher dimensional compactified cosmic string with magnetic fluxes, along the string core and also enclosed by the compactified direction, in thermal equilibrium at finite temperature $T$. These densities are calculated by decomposing them into the vacuum expectation values and finite temperature contributions coming from the particles and antiparticles. The only nonzero components correspond to the charge, azimuthal and axial current densities. By using the Abel-Plana formula, we decompose the components of the densities into the part induced by the cosmic string and the one by the compactification. The charge density is an odd function of the chemical potential and even periodic function of the magnetic flux with a period equal to the quantum flux. Moreover, the azimuthal (axial) current density is an even function of the chemical potentia...
Abelian cosmic string in the Starobinsky model of gravity
Morais Graça, J. P.
2016-03-01
In this paper, I analyze numerically the behaviour of the solutions corresponding to an Abelian string in the framework of the Starobinsky model. The role played by the quadratic term in the Lagrangian density f(R)=R+η {R}2 of this model is emphasized and the results are compared with the corresponding ones obtained in the framework of Einstein’s theory of gravity. I have found that the angular deficit generated by the string is lowered as the η parameter increases, allowing a well-behaved spacetime for a large range of values of the symmetry-breaking scale.
Abelian Cosmic String in the Starobinsky model of gravity
Graça, J P Morais
2015-01-01
In this paper, I analyze numerically the behaviour of the solutions corresponding to an Abelian string in the framework of the Starobinsky model. The role played by the quadratic term in the Lagrangian density $f(R) = R + \\eta R^2$ of this model is emphasized and the results are compared with the corresponding ones obtained in the framework of Einstein's theory of gravity. I have found that the angular deficit generated by the string is lowered as the $\\eta$ parameter increases, allowing a well-behaved spacetime for a large range of values of the symmetry-breaking scale.
Isospin Invariance and the Vacuum Polarization Energy of Cosmic Strings
Weigel, H; Graham, N
2016-01-01
We corroborate the previously applied spectral approach to compute the vacuum polarization energy of string configurations in models similar to the standard model of particle physics. The central observation underlying this corroboration is the existence of a particular global isospin transformation of the string configuration. Under this transformation the single particle energies of the quantum fluctuations are invariant, while the inevitable implementation of regularization and renormalization requires operations that are not invariant. We verify numerically that all such variances eventually cancel, and that the vacuum polarization energy obtained in the spectral approach is indeed gauge invariant.
Discussing cosmic string configurations in a supersymmetric scenario without Lorentz invariance
International Nuclear Information System (INIS)
The main goal of this work is to pursue an investigation of cosmic string configurations focusing on possible consequences of Lorentz-symmetry breaking by a background vector. We analyze the possibility of cosmic strings as a viable source for fermionic cold dark matter particles. Whenever the latter are charged and have mass of the order of 1013 GeV, we propose they could decay into usual cosmic rays. We have also contemplated the sector of neutral particles generated in our model. Indeed, being neutral, these particles are hard to detect; however, by virtue of the Lorentz-symmetry breaking background vector, it is possible that they may present electromagnetic interaction with a significant magnetic moment.
Gravitational waves from light cosmic strings: Backgrounds and bursts with large loops
International Nuclear Information System (INIS)
The mean spectrum and burst statistics of gravitational waves produced by a cosmological population of cosmic string loops are estimated using analytic approximations, calibrated with earlier simulations. Formulas are derived showing the dependence of observables on the string tension Gμ, in the regime where newly-formed loops are relatively large, not very much smaller than the horizon. Large loops form earlier, are more abundant, and generate a more intense stochastic background and more frequent bursts than assumed in earlier background estimates, enabling experiments to probe lighter cosmic strings of interest to string theory. Predictions are compared with instrument noise from current and future experiments, and with confusion noise from known astrophysical gravitational-wave sources such as stellar and massive black hole binaries. In these large-loop models, current data from millisecond pulsar timing already suggests that Gμ is less than about 10-10, close to the minimum value where bursts might be detected by Advanced LIGO, and a typical value expected in strings from brane inflation. Because of confusion noise expected from massive black hole binaries, pulsar techniques will not be able to go below about Gμ≅10-11. LISA will be sensitive to stochastic backgrounds created by strings as light as Gμ≅10-15, at frequencies where it is limited by confusion noise of Galactic stellar populations; however, for those lightest detectable strings, bursts are rarely detectable. For Gμ>10-11, the stochastic background from strings dominates the LISA noise by a large factor, and burst events may also be detectable by LISA, allowing detailed study of loop behavior. Astrophysical confusion might be low enough at 0.1 to 1 Hz to eventually reach Gμ≅10-20 with future interferometer technology
Fermionic vacuum polarization by a cosmic string in de Sitter spacetime
de Mello, E R Bezerra
2010-01-01
We investigate the fermionic condensate and the vacuum expectation value of the energy-momentum tensor for a massive spinor field in the geometry of a straight cosmic string on background of de Sitter spacetime. By using the Abel-Plana summation formula, we explicitly extract form the expectation values the contribution associated with purely de Sitter space, remaining the expectation values induced by the cosmic string. The latter presents information about de Sitter gravity as well. Because the investigation of the fermionic quantum fluctuations in de Sitter space have been investigated in literature, here we are mainly interested in the cosmic string-induced contributions. For a massless field, the fermionic condensate vanishes and the presence of the string does not break chiral symmetry of the massless theory. Unlike to the case of a scalar field, for a massive fermionic field the vacuum expectation value of the energy-momentum tensor is diagonal and the axial and radial stresses are equal to the energy ...
High redshift signatures in the 21 cm forest due to cosmic string wakes
Energy Technology Data Exchange (ETDEWEB)
Tashiro, Hiroyuki [Physics Department, Arizona State University, Tempe, AZ, 85287 (United States); Sekiguchi, Toyokazu [Department of Physics and Astrophysics, Nagoya University, Nagoya, 464–8602 (Japan); Silk, Joseph, E-mail: hiroyuki.tashiro@asu.edu, E-mail: toyokazu.sekiguchi@nagoya-u.jp, E-mail: silk@astro.ox.ac.uk [Institut d' Astrophysique, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Blvd Arago, Paris, 75014 (France)
2014-01-01
Cosmic strings induce minihalo formation in the early universe. The resultant minihalos cluster in string wakes and create a ''21 cm forest'' against the cosmic microwave background (CMB) spectrum. Such a 21 cm forest can contribute to angular fluctuations of redshifted 21 cm signals integrated along the line of sight. We calculate the root-mean-square amplitude of the 21 cm fluctuations due to strings and show that these fluctuations can dominate signals from minihalos due to primordial density fluctuations at high redshift (z∼>10), even if the string tension is below the current upper bound, Gμ < 1.5 × 10{sup −7}. Our results also predict that the Square Kilometre Array (SKA) can potentially detect the 21 cm fluctuations due to strings with Gμ ≈ 7.5 × 10{sup −8} for the single frequency band case and 4.0 × 10{sup −8} for the multi-frequency band case.
Analytical model for CMB temperature angular power spectrum from cosmic (super-)strings
Yamauchi, Daisuke; Takahashi, Keitaro; Sendouda, Yuuiti; Yoo, Chul-Moon; Sasaki, Misao
2010-01-01
We present a new analytical method to calculate the small angle CMB temperature angular power spectrum due to cosmic (super-)string segments. In particular, using our method, we clarify the dependence on the intercommuting probability $P$. We find that the power spectrum is dominated by Poisson-distributed string segments. The power spectrum for a general value of $P$ has a plateau on large angular scales and shows a power-law decrease on small angular scales. The resulting spectrum in the ca...
Vacuum polarization induced by a cosmic string in anti-de Sitter spacetime
International Nuclear Information System (INIS)
In this paper, we investigate the vacuum expectation values (VEVs) of the field squared and the energy–momentum tensor associated with a massive scalar quantum field induced by a generalized cosmic string in D-dimensional anti-de Sitter (AdS) spacetime. In order to develop this analysis we evaluate the corresponding Wightman function. As we shall observe, this function is expressed as the sum of two terms: the first one corresponds to the Wightman function in pure AdS bulk and the second one is induced by the presence of the string. The second contribution is finite at the coincidence limit and is used to provide closed expressions for the parts in the VEVs of the field squared and the energy–momentum tensor induced by the presence of the string. Because the analysis of vacuum polarization effects in pure AdS spacetime has been developed in the literature, here we are mainly interested in the investigation of string-induced effects. We show that the curvature of the background spacetime has an essential influence on the VEVs at distances larger than the curvature radius. In particular, at large distances the decay of the string-induced VEVs is power law for both massless and massive fields. The string-induced parts vanish on the AdS boundary and they dominate the pure AdS part for points near the AdS horizon. (paper)
Gravitational-Wave Stochastic Background from Kinks and Cusps on Cosmic Strings
Olmez, S.; Mandic, V.; Siemens, X.
2010-01-01
We compute the contribution of kinks on cosmic string loops to stochastic background of gravitational waves (SBGW).We find that kinks contribute at the same order as cusps to the SBGW.We discuss the accessibility of the total background due to kinks as well as cusps to current and planned gravitational wave detectors, as well as to the big bang nucleosynthesis (BBN), the cosmic microwave background (CMB), and pulsar timing constraints. As in the case of cusps, we find that current data from i...
Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Spacetime
Spinelly, J
2007-01-01
In this paper we analyse the effect produced by the temperature in the vacuum polarization associated with charged massless scalar field in the presence of magnetic flux tube in the cosmic string spacetime. Three different configurations of magnetic fields are taken into account: $(i)$ a homogeneous field inside the tube, $(ii)$ a field proportional to $1/r$ and $(iii)$ a cylindrical shell with $\\delta$-function. In these three cases, the axis of the infinitely long tube of radius $R$ coincides with the cosmic string. Because the complexity of this analysis in the region inside the tube, we consider the thermal effect in the region outside. In order to develop this analysis, we construct the thermal Green function associated with this system for the three above mentioned situations considering points in the region outside the tube. We explicitly calculate in the high-temperature limit, the thermal average of the field square and the energy-momentum tensor.
Heat Kernel expansion on a cone and quantum fields near cosmic strings
International Nuclear Information System (INIS)
An asymptotic expansion of the trace of the heat kernel on a cone where the heat coefficients have a delta function behaviour at the apex is obtained. It is used to derive the renormalized effective action and total energy of a self-interacting quantum scalar field on the cosmic string space-time. Analogy is pointed out with quantum theory with boundaries. The surface infinities in the effective action are shown to appear and are removed by renormalization of the string tension. Besides the total renormalized energy turns out to be finite due to cancellation of the known non-integrable divergence in the energy density of the field with a counterterm in the bare string tension
Wen, Hao; Li, Fangyu; Fang, Zhenyun(Department of Physics, Chongqing University, 400044, Chongqing, People’s Republic of China); Beckwith, Andrew
2014-01-01
The cosmic strings (CSs) may be one type of important source of gravitational waves (GWs), and it has been intensively studied due to its special properties such as the cylindrical symmetry. The CSs would generate not only usual continuous GWs, but also impulsive GWs that bring about a more concentrated energy and consist of different GW components, broadly covering low-, intermediate- and high-frequency bands simultaneously. These features might underlie interesting electromagnetic (EM) resp...
Gravitational Radiation and the Small-Scale Structure of Cosmic Strings
Siemens, Xavier; Olum, Ken D.
2001-01-01
We calculate the gravitational radiation emitted by an infinite cosmic string with two oppositely moving wave-trains, in the small amplitude approximation. After comparing our result to the previously studied cases we extend the results to a new regime where the wavelengths of the opposing wave-trains are very different. We show that in this case the amount of power radiated vanishes exponentially. This means that small excitations moving in only one direction may be very long lived, and so t...
Salazar-Ramírez, M.; Ojeda-Guillén, D.; Mota, R. D.
2016-09-01
We study a relativistic quantum particle in cosmic string spacetime in the presence of a magnetic field and a Coulomb-type scalar potential. It is shown that the radial part of this problem possesses the su(1 , 1) symmetry. We obtain the energy spectrum and eigenfunctions of this problem by using two algebraic methods: the Schrödinger factorization and the tilting transformation. Finally, we give the explicit form of the relativistic coherent states for this problem.
Stochastic background from cosmic (super)strings: Popcorn-like and (Gaussian) continuous regimes
Regimbau, Tania; Giampanis, Stefanos; Siemens, Xavier; Mandic, Vuk
2012-03-01
In the era of the next generation of gravitational wave experiments a stochastic background from cusps of cosmic (super)strings is expected to be probed and, if not detected, to be significantly constrained. A popcornlike background can be, for part of the parameter space, as pronounced as the (Gaussian) continuous contribution from unresolved sources that overlap in frequency and time. We study both contributions from unresolved cosmic string cusps over a range of frequencies relevant to ground based interferometers, such as the LIGO/Virgo second generation and Einstein Telescope third generation detectors, the space antenna LISA, and pulsar timing arrays. We compute the sensitivity (at the 2σ level) in the parameter space for the LIGO/Virgo second generation detector, the Einstein Telescope detector, LISA, and pulsar timing arrays. We conclude that the popcorn regime is complementary to the continuous background. Its detection could therefore enhance confidence in a stochastic background detection and possibly help determine fundamental string parameters such as the string tension and the reconnection probability.
Fermionic vacuum polarization by a cosmic string in anti-de Sitter spacetime
de Mello, E R Bezerra; Saharian, A A
2013-01-01
In this paper we investigate the fermionic condensate (FC) and the vacuum expectation value (VEV) of the energy-momentum tensor, associated with a massive fermionic field, induced by the presence of a cosmic string in the anti-de Sitter (AdS) spacetime. In order to develop this analysis we construct the complete set of normalized eigenfunctions in the corresponding spacetime. We consider a special case of boundary conditions on the AdS boundary, when the MIT bag boundary condition is imposed on the field operator at a finite distance from the boundary, which is then taken to zero. The FC and the VEV of the energy-momentum tensor are decomposed into the pure AdS and string-induced parts. Because the analysis of one-loop quantum effects in the AdS spacetime has been developed in the literature, here we are mainly interested to investigate the influence of the cosmic string on the VEVs. The string-induced part in the VEV of the energy-momentum tensor is diagonal and the axial and radial stresses are equal to the...
Fermionic vacuum polarization by a flat boundary in cosmic string spacetime
de Mello, E R Bezerra; Abajyan, S V
2012-01-01
In this paper we investigate the fermionic condensate and the renormalized vacuum expectation value (VEV) of the energy-momentum tensor for a massive fermionic field induced by a flat boundary in the cosmic string spacetime. In this analysis we assume that the field operator obeys MIT bag boundary condition on the boundary. We explicitly decompose the VEVs into the boundary-free and boundary-induced parts. General formulas are provided for both parts which are valid for any value of the parameter associated with the cosmic string. For a massless field, the boundary-free part in the fermionic condensate and the boundary-induced part in the energy-momentum tensor vanish. For a massive field the radial stress is equal to the energy density for both boundary-free and boundary-induced parts. The boundary-induced part in the stress along the axis of the cosmic string vanishes. The total energy density is negative everywhere, whereas the effective pressure along the azimuthal direction is positive near the boundary ...
Alignment of Quasar Polarizations on Large Scales Explained by Warped Cosmic Strings
Slagter, Reinoud Jan
2016-01-01
The recently discovered alignment of quasar polarizations on very large scales could possibly explained by considering cosmic strings on a warped five dimensional spacetime. Compact objects, such as cosmic strings, could have tremendous mass in the bulk, while their warped manifestations in the brane can be consistent with general relativity in 4D. The self-gravitating cosmic string induces gravitational wavelike disturbances which could have effects felt on the brane, i.e., the massive effective 4D modes (Kaluza-Klein modes) of the perturbative 5D graviton. This effect is amplified by the time dependent part of the warp factor. Due to this warp factor, disturbances don't fade away during the expansion of the universe. From a non-linear perturbation analysis it is found that the effective Einstein 4D equations on an axially symmetric spacetime, contain a "back-reaction" term on the righthand side caused by the projected 5D Weyl tensor and can act as a dark energy term. The propagation equations to first order...
The evolution of FLRW spacetime after the birth of a cosmic string
Lake, Matthew
2012-01-01
We consider the evolution of an initially FLRW universe after the formation of a long, straight, cosmic string with arbitrary tension and mass per unit length. The birth of the string sources scalar and tensor-type perturbations in the background metric and both density and velocity perturbations in the background fluid, which compensate for the string mass and maintain energy conservation. The former generate the deficit angle within the light cone of the string and a gravitational shock front at the cosmological horizon, whereas the latter are confined within the sound cone. We study the properties of the metric within each region of the resulting spacetime and give the explicit coordinate transformations which demonstrate non-violation of causality. This paper generalizes the work of Magueijo, who performed a similar analysis for the Nambu-Goto (NG) string, but the solutions given here differ from the ones he obtained, even in the NG limit. We believe this to be a consequence of the choice of boundary cond...
Cosmic strings and the origin of structure in the universe
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The observed universe is homogeneous and isotropic on the largest observable scales. The best evidence for this comes from observations of the cosmic background radiation (CBR). On smaller scales, a striking amount of structure can be seen - galaxies, clusters of galaxies, and the large scale structure in the form of possible filaments, bubbles, sheets or voids. The best proximate explanation for this structure is small amplitude perturbations in the early universe, which grew by gravitational instability into the observed large scale structure during the expansion of the universe. At some time in the future when we have a complete theory of the universe and its initial conditions - see James Hartle's lectures in this volume for some promising ideas toward such a theory - both the overall homogeneity and the structure should be a calculable consequence of the theory. Until then, people have made partial progress toward understanding the genesis of structure on a homogeneous background, based on the laws of fundamental physics as currently known. At this time we have at least two possible fundamental mechanisms for generation of the conjectural initial perturbations, namely quantum fluctuations, or thermodynamic fluctuations of a particular sort. The authors purpose in these lectures is to review and outline the basic physical nature of these two mechanisms, leaving out the details. Both mechanisms are well reviewed in the literature, and the reader will be referred both to more comprehensive reviews and to the primary literature throughout these lectures. 35 references, 2 tables
Finite temperature bosonic charge and current densities in compactified cosmic string spacetime
Mohammadi, A.; Bezerra de Mello, E. R.
2016-06-01
In this paper, we study the expectation values of the induced charge and current densities for a massive bosonic field with nonzero chemical potential in the geometry of a higher-dimensional compactified cosmic string with magnetic fluxes along the string core and also enclosed by the compactified direction in thermal equilibrium at finite temperature T . These densities are calculated by decomposing them into the vacuum expectation values and finite temperature contributions coming from the particles and antiparticles. The only nonzero components correspond to the charge, azimuthal, and axial current densities. By using the Abel-Plana formula, we decompose the components of the densities into the part induced by the cosmic string and the one by the compactification. The charge density is an odd function of the chemical potential and even periodic function of the magnetic flux with a period equal to the quantum flux. Moreover, the azimuthal (axial) current density is an even function of the chemical potential and an odd (even) periodic function of the magnetic flux with the same period. In this paper, our main concern is the thermal effect on the charge and current densities, including some limiting cases, the low- and high-temperature approximations. We show that in all cases, the temperature enhances the induced densities.
Vacuum polarization induced by a cosmic string in anti-de Sitter spacetime
de Mello, E R Bezerra
2011-01-01
In this paper we investigate the vacuum expectation values (VEVs) of the field squared and the energy-momentum tensor associated with a massive scalar quantum field induced by a generalized cosmic string in D-dimensional anti-de Sitter (AdS) spacetime. In order to develop this analysis we evaluate the corresponding Wightman function. As we shall observe, this function is expressed as the sum of two terms: the first one corresponds to the Wightman function in pure AdS bulk and the second one is induced by the presence of the string. The second contribution is finite at coincidence limit and is used to provide closed expressions for the parts in the VEVs of the field squared and the energy-momentum tensor induced by the presence of the string. Because the analysis of vacuum polarizations effects in pure AdS spacetime have been developed in the literature, here we are mainly interested in the investigation of string-induced effects. We show that the curvature of the background spacetime has an essential influenc...
Non-Abelian cosmic strings in de Sitter and anti-de Sitter space
Santos, Antônio de Pádua
2015-01-01
In this paper we investigate the non-Abelian cosmic string in de Sitter and anti-de Sitter spacetimes. In order to do that we construct the complete set of equations of motion considering the presence of a cosmological constant. By using numerical analysis we provide the behavior of the Higgs and gauge fields and also for the metric tensor for specific values of the physical parameters of the theory. For de Sitter case, we find the appearance of horizons that although being consequence of the presence of the cosmological constant it strongly depends on the value of the gravitational coupling. In the anti-de Sitter case, we find that the system does not present horizons. In fact the new feature of this system is related with the behavior of the $(00)$ and $(zz)$ components of the metric tensor. They present a strongly increasing for large distance from the string.
Muon production and string percolation effects in cosmic rays at the highest energies
Alvarez-Muñiz, J; Conceição, R; de Deus, J Dias; Pajares, C; Pimenta, M
2012-01-01
Ultra High Energy Cosmic Rays with energies above ~ 10^18 eV provide an unique window to study hadronic interactions at energies well above those achieved in the largest man-made accelerators. We argue that at those energies string percolation may occur and play an important role on the description of the induced Extensive Air Showers by enhancing strangeness and baryon production. This leads to a significant increase of the muon content of the cascade in agreement with recent data collected at UHECR experiments. In this work, the effects of string percolation in hadronic interactions are implemented in an EAS code and their impact on several shower observables is evaluated and discussed.
Propagation of cosmic rays through the atmosphere in the quark-gluon strings model
Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.
1985-01-01
The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.
Scalar bosons under the influence of noninertial effects in the cosmic string spacetime
Santos, L C N
2016-01-01
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 bound states when the Klein-Gordon equation is considered in this kind of spacetime.
Fractal geometry of cosmic strings and correlations among galaxies and Abell clusters
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In the context of the cosmic-string picture of galaxy and cluster formation we develop a model for the loop correlation function. Assuming that parent loops have dimension 1 and that the production of child loops cut off from the parent with a peculiar velocity v is described by a Brownian random walk we estimate for the fractal dimension of the correlations D = 1+3.28v2. For v≅0.24 this gives the observed fractal D≅1.2
Anomalous Fluctuations in Observations of Q0957+561 A,B: Smoking Gun of a Cosmic String?
Schild, R; Hnatyk, B; Zhdanov, V I
2004-01-01
We report the detection of anomalous brightness fluctuations in the multiple image Q0957+561 A,B gravitational lens system, and consider whether such anomalies have a plausible interpretation within the framework of cosmic string theory. We study a simple model of gravitational lensing by an asymmetrical rotating string. An explicit form of the lens equation is obtained and approximate relations for magnification are derived. We show that such a model with typical parameters of the GUT string can quantitatively reproduce the observed pattern of brightness fluctuations. On the other hand, explanation involving a binary star system as an alternative cause requires an unacceptably large massive object at a small distance. We also discuss possible observational manifestations of cosmic strings within our lens model.
Spinelly, J
2003-01-01
In this paper we consider a charged massless scalar quantum field operator in the spacetime of an idealized cosmic string, i.e., an infinitely long, straight and static cosmic string, which presents a magnetic field confined in a cylindrical tube of finite radius. Three distinct situations are taking into account in this analysis: {\\it{i)}} a homogeneous field inside the tube, {\\it{ii)}} a magnetic field proportional to $1/r$ and {\\it{iii)}} a cylindrical shell with $\\delta$-function. In these three cases the axis of the infinitely long tube of radius $R$ coincides with the cosmic string. In order to study the vacuum polarization effects outside the tube, we explicitly calculate the Euclidean Green function associated with this system for the three above situations, considering points in the region outside the tube.
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Vacuum correlators of the electric and magnetic fields are calculated in the geometry of a cosmic string. Formulas for the vacuum expectation values for the squares of field components are derived. The forces acting on an atom due to the vacuum fluctuations are investigated. For atoms with isotropic tensor of polarizability these forces are attractive with respect to the string. In the anisotropic case, depending on the eigenvalues of the polarizability tensor, the Casimir-Polder forces can be either attractive or repulsive
Accretion of Cold and Hot Dark Matter onto Cosmic String Filaments
Zanchin, V T; Brandenberger, R H
1996-01-01
The Zeldovich approximation is applied to study the accretion of hot and cold dark matter onto moving long strings. It is assumed that such defects carry a substantial amount of small-scale structure, thereby acting gravitationally as a Newtonian line source whose effects dominate the velocity perturbations. Analytical expressions for the turn-around surfaces are derived and the mass inside of these surfaces is calculated. Estimates are given for the redshift dependence of $\\Omega_{nl}$, the fraction of mass in nonlinear objects. Depending on parameters, it is possible to obtain $\\Omega_{nl} = 1$ at the present time. Even with hot dark matter, the first nonlinear filamentary structures form at a redshift close to 100, and there is sufficient nonlinear mass to explain the observed abundance of high redshift quasars and damped Lyman alpha systems. These results imply that moving strings with small-scale structure are the most efficient seeds to produce massive nonlinear objects in the cosmic string model.
Belich, H
2015-01-01
The behaviour of a relativistic scalar particle subject to a scalar potential under the effects of the violation of the Lorentz symmetry in the cosmic string spacetime is discussed. It is considered two possible scenarios of the Lorentz symmetry breaking in the CPT-even gauge sector of the Standard Model Extension defined by a tensor $\\left(K_{F}\\right)_{\\mu\
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We calculate the renormalized vacuum polarization and stress tensor for a massless, arbitrarily coupled scalar field in the Hartle-Hawking vacuum state on the horizon of a Schwarzschild black hole threaded by an infinite straight cosmic string. This calculation relies on a generalized Heine identity for non-integer Legendre functions which we derive without using specific properties of the Legendre functions themselves.
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In this paper we investigate the vacuum polarization effects associated with quantum fermionic charged fields in a generalized (d+1)-dimensional cosmic string space-times considering the presence of a magnetic flux along the string. In order to develop this analysis we calculate a general expression for the respective Green function, valid for several different values of d, which is expressed in terms of a bispinor associated with the square of the Dirac operator. Adopting this result, we explicitly calculate the renormalized vacuum expectation values of the energy-momentum tensors, (TAB)Ren., associated with massless fields. Moreover, for specific values of the parameters which codify the cosmic string and the fractional part of the ratio of the magnetic flux by the quantum one, we were able to present in closed forms the bispinor and the respective Green function for massive fields.
Bezerra, V B; Fonseca-Neto, J B; Sobreira, A A R
2003-01-01
We obtain the solution that corresponds to a time-like current-carrying screwed cosmic string (TCSCS) in the framework of a general scalar-tensor theory including torsion, using the weak field approximation. We show that the presence of torsion induces other properties different from that in which torsion is absent. When the spin vanishes, this torsion is $phi$-gradient and then it propagates outside of the string. We investigate the effects of current and torsion on the gravitational force and on the geodesics of a test-particle moving around the TCSCS. We also consider the linear pertubation methods developed by Zel'dovich in this case and investigate the accretion of cold dark matter by wakes formation when a TCSCS moves with speed v . Our results are compared with those obtained for cosmic strings in the framework of scalar-tensor theories without taking torsion into account.
Wen, H; Fang, Z Y; Beckwith, A
2014-01-01
The cosmic strings(CSs) may be one important source of gravitational waves(GWs), and it has been intensively studied due to its special properties such as the cylindrical symmetry. The CSs would generate not only usual continuous GW, but also impulsive GW that brings more concentrated energy and consists of different GW components broadly covering low-, intermediate- and high-frequency bands simultaneously. These features might underlie interesting electromagnetic(EM) response to these GWs generated by the CSs. In this paper, with novel results and effects, we firstly calculate the analytical solutions of perturbed EM fields caused by interaction between impulsive cylindrical GWs (would be one of possible forms emitted from CSs) and background celestial high magnetic fields or widespread cosmological background magnetic fields, by using rigorous Einstein - Rosen metric. Results show: perturbed EM fields are also in the impulsive form accordant to the GW pulse, and asymptotic behaviors of the perturbed EM fiel...
Topology, cosmic strings and quantum dynamics – a case study with graphene
International Nuclear Information System (INIS)
We explore the possibility to study the quantum dynamics of Dirac fermions in presence of a cosmic string by introducing a conical topological defect in gapped graphene in the presence of a Coulomb charge. When the Coulomb charge exceeds a certain critical strength, quantum instability sets in. Below the critical regime and for certain values of the system parameters, the allowed boundary conditions in gapped graphene cone can be classified in terms of a single real quantity. Observables such as local density of states, scattering phase shifts and the bound state spectra are dependent on the value of this real parameter, which has to be determined empirically. For a supercritical Coulomb charge, we analyze the system with a regularized potential as well as with a zigzag boundary condition and find the effect of the sample topology on the observable features of the system.
Induced fermionic current by a magnetic flux in a cosmic string spacetime at finite temperature
Bezerra de Mello, Eugênio R.; Saharian, Aram A.; Mohammadi, Azadeh
2016-01-01
Here we analyze the finite temperature expectation values of the charge and current densities for a massive fermionic quantum field with nonzero chemical potential μ, induced by a magnetic flux running along the axis of an idealized cosmic string. These densities are decomposed into the vacuum expectation values and contributions coming from the particles and antiparticles. Specifically the charge density is an even periodic function of the magnetic flux with the period equal to the quantum flux and an odd function of the chemical potential. The only nonzero component of the current density corresponds to the azimuthal current and it is an odd periodic function of the magnetic flux and an even function of the chemical potential. Both analyzed are developed for the cases where |μ| is smaller than the mass of the field quanta m.
Mohammadi, A; Saharian, A A
2014-01-01
We investigate the finite temperature expectation values of the charge and current densities for a massive fermionic field with nonzero chemical potential, $\\mu$, in the geometry of a straight cosmic string with a magnetic flux running along its axis. These densities are decomposed into the vacuum expectation values and contributions coming from the particles and antiparticles. The charge density is an even periodic function of the magnetic flux with the period equal to the quantum flux and an odd function of the chemical potential. The only nonzero component of the current density corresponds to the azimuthal current. The latter is an odd periodic function of the magnetic flux and an even function of the chemical potential. At high temperatures, the parts in the charge density and azimuthal current induced by the planar angle deficit and magnetic flux are exponentially small. The asymptotic behavior at low temperatures crucially depends whether the value $|\\mu|$ is larger or smaller than the mass of the fiel...
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We study the gravitational shock waves generated by ultrarelativistic extended sources, mainly when cosmic strings (local, global, spinning and supeconducting) and other topological defects (monopoles and domain walls) are boosted and become ultrarelativistic. In this limit, the source travel at the speed of light and the physical parameters (mass, charges and spin) must be taken γ-dependent [γ = (1-υ2)-1/2] and must vanish in an appropriated way. The scattering matrices of Klein-Gordon fields in these geometries are computed and the low- and high-energy behaviour analysed. Comparison with the scattering by point-like sources (Aichelburg-Sexl geometry for which the S-matrix has coulombian type poles) is made. For extended as well as point-like sources, the ultrarelativistic limit and the weak-field limit (or large-distance behaviour) of the geometry give the same scattering matrices. (orig.)
Boundary conditions for quantum mechanics on cones and fields around cosmic strings
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We study the options for boundary conditions at the conical singularity for quantum mechanics on a two-dimensional cone with deficit angle ≤2π and for classical and quantum scalar fields propagating with a translationally invariant dynamics in the 1+3 dimensional spacetime around an idealized straight infinitely long, infinitesimally thin cosmic string. The key to our analysis is the observation that minus-the-Laplacian on a cone possesses a one-parameter family of self-adjoint extensions. These may be labeled by a parameter R with the dimensions of length - taking values in (0, ∞). We discuss the relevance of the various idealized dynamics to quantum mechanics on a cone with a rounded-off centre and field theory around a 'true' string of finite thickness. Provided one is interested in effects at sufficiently large length scales, the 'true' dynamics will depend on the details of the interaction of the wave function with the cone's centre only through a single parameter R and will be well-approximated by the dynamics for the corresponding idealized problem with the same R-value. This turns out to be zero if the interaction with the centre is purely gravitational and minimally coupled, but non-zero values can be important to model non-gravitational interactions. Especially, we point out the relevance of non-zero R-values to electromagnetic waves around superconducting strings. We also briefly speculate on the relevance of the R-parameter in the application of quantum mechanics on cones to 1+2 dimensional quantum gravity with massive scalars. (orig.)
Big-Bang Nucleosynthesis and Gamma-Ray Constraints on Cosmic Strings with a large Higgs condensate
Mota, H F Santana
2014-01-01
We consider constraints on cosmic strings from their emission of Higgs particles, in the case that the strings have a Higgs condensate with amplitude of order the string mass scale, assuming that a fraction of the energy of condensate can be turned into radiation near cusps. The injection of energy by the decaying Higgs particles affects the light element abundances predicted by standard Big-Bang Nucleosynthesis (BBN), and also contributes to the Diffuse Gamma-Ray Background (DGRB) in the universe today. We examine the two main string scenarios (Nambu-Goto and field theory), and find that the primordial Helium abundance strongly constrains the string tension and the efficiency of the emission process. The Fermi-LAT measurement of the DGRB constrains the field theory scenario (but not the NG scenario) even more strongly, requiring that the product of the string tension {\\mu} and Newton's constant G is bounded by G{\\mu} < 3x10^{-11}{\\beta}_{ft}^{-2}, where {\\beta}_{ft}^2 is the fraction of the strings' energ...
Bianchi Type-V Bulk Viscous Cosmic String in f(R,T) Gravity with Time Varying Deceleration Parameter
Bishi, Bïnaya K.; Mahanta, K. L.
2015-01-01
We study the Bianchi type-V string cosmological model with bulk viscosity in f(R,T) theory of gravity by considering a special form and linearly varying deceleration parameter. This is an extension of the earlier work of Naidu et al., 2013, where they have constructed the model by considering a constant deceleration parameter. Here we find that the cosmic strings do not survive in both models. In addition we study some physical and kinematical properties of both models. We observe that in one...
Polchinski, Joseph
2005-01-01
We classify potential cosmic strings according to the topological charge measurable outside the string core. We conjecture that in string theory it is this charge that governs the stability of long strings. This would imply that the SO(32) heterotic string can have endpoints, but not the E_8 x E_8 heterotic string. We give various arguments in support of this conclusion.
Scattering and bound states of a spin--1/2 neutral particle in the cosmic string spacetime
Silva, Edilberto O; Filgueiras, Cleverson
2016-01-01
In this paper the relativistic quantum dynamics of a spin-1/2 neutral particle with a magnetic moment $\\mu$ in the cosmic string spacetime is reexamined by applying the von Neumann theory of self-adjoint extensions. Contrary to previous studies where the interaction between the spin and the line of charge were neglected, here we consider its effects. This interaction gives rise to a point interaction: $\\boldsymbol{\
Hosseinpour, Mansoureh; Silva, Edilberto O; Hassanabadi, Hassan
2016-01-01
We study the covariant Dirac equation in the space-time generated by a cosmic string in presence of vector and scalar potentials of electromagnetic field. We obtain the solution of the radial part of Dirac equation. We consider the scattering states under the Hulth\\'{e}n potential and obtain the phase shifts. From the poles of the scattering $S$-matrix the bound states energies are determined as well.
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We present a FORTRAN-77 code for the simulation of the dynamical interactions of cosmic strings. This code also simulates the interactions of tubes of magnetic flux trapped in a superconducting material. The code has been written to take advantage of the vector architecture and data motion features of the ETA-10 supercomputer; however, it is written entirely in standard FORTRAN-77 so that it is quite portable and may also be run on scalar machines for testing and development. (orig.)
Binétruy, Pierre; Caprini, Chiara; Dufaux, Jean-François
2012-01-01
We review the main cosmological backgrounds of gravitational waves accessible to detectors in space sensitive to the range $10^{-4}$ to $10^{-1}$ Hz, with a special emphasis on those backgrounds due to phase transitions or networks of cosmic strings. We apply this to identify the scientific potential of the NGO/eLISA mission of ESA, regarding the detectability of such cosmological backgrounds.
Henrot-Versillé, Sophie; Robinet, Florent; Leroy, Nicolas; Plaszczynski, Stéphane; Arnaud, Nicolas; Bizouard, Marie-Anne; Cavalier, Fabien; Christensen, Nelson; Couchot, François; Franco, Samuel; Hello, Patrice; Huet, Dominique; Kasprzack, Marie; Perdereau, Olivier; Spinelli, Marta; Tristram, Matthieu
2015-02-01
The production of a primordial stochastic gravitational-wave (GW) background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the cosmic microwave background (CMB) or the baryon acoustic oscillations (BAO) can be used to set upper limits on the stochastic GW background energy density {{Ω }GW} for frequencies above 10-15 Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-ℓ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that {{Ω }GW}h02\\lt 3.8× {{10}-6} at a 95% confidence level for adiabatic initial conditions, which improves over the previous limit by a factor 2.3. Assuming that the primordial GW has been produced by a network of cosmic strings, we have derived exclusion limits in the cosmic string parameter space. If the size of the loops is determined by gravitational back-reaction, string tension values greater than ˜4 × {{10}-9} are excluded for a reconnection probability of 10-3.
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The production of a primordial stochastic gravitational-wave (GW) background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the cosmic microwave background (CMB) or the baryon acoustic oscillations (BAO) can be used to set upper limits on the stochastic GW background energy density ΩGW for frequencies above 10−15 Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-ℓ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that ΩGWh02<3.8×10−6 at a 95% confidence level for adiabatic initial conditions, which improves over the previous limit by a factor 2.3. Assuming that the primordial GW has been produced by a network of cosmic strings, we have derived exclusion limits in the cosmic string parameter space. If the size of the loops is determined by gravitational back-reaction, string tension values greater than ∼4 × 10−9 are excluded for a reconnection probability of 10−3. (paper)
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In this paper, we consider a charged massless scalar quantum field operator in the spacetime of an idealized cosmic string, i.e., an infinitely long, straight and static cosmic string, which presents a magnetic field confined in a cylindrical tube of finite radius. Three distinct situations are taken into account in this analysis: (i) a homogeneous field inside the tube, (ii) a magnetic field proportional to 1/r and (iii) a cylindrical shell with δ-function. In these three cases, the axis of the infinitely long tube of radius R coincides with the cosmic string. In order to study the vacuum polarization effects outside the tube, we explicitly calculate the Euclidean Green function associated with this system for the three above situations, considering points in the region outside the tube. Having these Green functions we calculate the renormalized vacuum expectation values, { hat Φ * (x) hat Φ Ren and ( hat T ν μ (x) } Ren, associated with the charged field. In the evaluation of these vacuum polarization effects, two contributions appear for the three models. The first are the standard ones due to the conical geometry of the spacetime and the magnetic flux. The second contributions appear as extra terms. They are corrections due to the finite thickness of the radius of the tube. These extra terms provide relevant contributions, even for points very far away from the system, like a long-range effect
The Motion of Cosmic Strings in the Schwarzschild Black Hole Spacetime
Roshchupkin, Sergey
2003-01-01
We study the classical dynamics of a bosonic string in the Schwarzschild spacetime using a perturbative scheme which is based on the assumption of a small value of a rescaled string tension parameter. The proposed approximation selfconsistently describes the string dynamics on the scale of large values for the worldsheet time in a fixed gauge.
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The cosmic strings (CSs) may be one type of important source of gravitational waves (GWs), and it has been intensively studied due to its special properties such as the cylindrical symmetry. The CSs would generate not only usual continuous GWs, but also impulsive GWs that bring about a more concentrated energy and consist of different GW components, broadly covering low-, intermediate- and high-frequency bands simultaneously. These features might underlie interesting electromagnetic (EM) responses to these GWs generated by the CSs. In this paper, with novel results and effects, we firstly calculate the analytical solutions of perturbed EM fields caused by the interaction between impulsive cylindrical GWs (which would be one of possible forms emitted from CSs) and background celestial high magnetic fields or widespread cosmological background magnetic fields, by using the exact form of the Einstein-Rosen metric rather than the planar approximation usually applied. The results show that perturbed EM fields are also in the impulsive form in accordant to the GW pulse, and the asymptotic behaviors of the perturbed EM fields are fully consistent with the asymptotic behaviors of the energy density, energy flux density, and Riemann curvature tensor of the corresponding impulsive cylindrical GWs. The analytical solutions naturally give rise to the accumulation effect (due to the synchro-propagation of perturbed EM fields and the GW pulse, because of their identical propagating velocities, i.e., the speed of light), which is proportional to the √(distance). Based on this accumulation effect, in consideration of very widely existing background galactic-extragalactic magnetic fields in all galaxies and galaxy clusters, we for the first time predict potentially observable effects in the region of the Earth caused by the EM response to GWs from the CSs. (orig.)
Bianchi Type-V Bulk Viscous Cosmic String in f(R,T Gravity with Time Varying Deceleration Parameter
Directory of Open Access Journals (Sweden)
Bïnaya K. Bishi
2015-01-01
Full Text Available We study the Bianchi type-V string cosmological model with bulk viscosity in f(R,T theory of gravity by considering a special form and linearly varying deceleration parameter. This is an extension of the earlier work of Naidu et al., 2013, where they have constructed the model by considering a constant deceleration parameter. Here we find that the cosmic strings do not survive in both models. In addition we study some physical and kinematical properties of both models. We observe that in one of our models these properties are identical to the model obtained by Naidu et al., 2013, and in the other model the behavior of these parameters is different.
International Nuclear Information System (INIS)
We review several cosmological backgrounds of gravitational waves accessible to direct-detection experiments, with a special emphasis on those backgrounds due to first-order phase transitions and networks of cosmic (super-)strings. For these two particular sources, we revisit in detail the computation of the gravitational wave background and improve the results of previous works in the literature. We apply our results to identify the scientific potential of the NGO/eLISA mission of ESA regarding the detectability of cosmological backgrounds
Smolyaninov, Igor I; Smolyaninov, Alexei I
2014-01-01
Cobalt nanoparticle-based ferrofluid in the presence of external magnetic field forms a self-assembled hyperbolic metamaterial. Wave equation describing propagation of extraordinary light inside the ferrofluid exhibits 2+1 dimensional Lorentz symmetry. The role of time in the corresponding effective 3D Minkowski spacetime is played by the spatial coordinate directed along the periodic nanoparticle chains aligned by the magnetic field. Here we present a microscopic study of point, linear and volume defects of the nanoparticle chain structure and demonstrate that they may exhibit strong similarities with such Minkowski spacetime defects as magnetic monopoles, cosmic strings and the recently proposed spacetime cloaks. Experimental observations of such defects are described.
Bakke, K.
2015-07-01
The behaviour of the Landau-Aharonov-Casher system is discussed by showing a case where the external electric field cannot yield the Landau-Aharonov-Casher quantization under the influence of rotating effects in the cosmic string spacetime, but it can yield bound states solutions to the Schrödinger-Pauli equation analogous to having the Landau-Aharonov-Casher system confined to a hard-wall confining potential under the influence of rotating effects and the topology of the cosmic string spacetime (by assuming ω ρ≪1 and neglecting the effects of a gravitational self-force on the particle).
Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Space-Time
Spinelly, J.; Bezerra de Mello, E. R.
In this paper, we analyze the effect produced by the temperature in the vacuum polarization associated with a charged massless scalar field in the presence of a magnetic flux tube in the cosmic string space-time. Three different configurations of magnetic fields are taken into account: (i) a homogeneous field inside the tube, (ii) a field proportional to 1/r, and (iii) a cylindrical shell with δ-function. In these three cases, the axis of the infinitely long tube of radius R coincides with the cosmic string. Because of the complexity of this analysis in the region inside the tube, we consider the thermal effect in the region outside. In order to develop this analysis, we construct the thermal Green function associated with this system for the three above-mentioned situations considering points in the region outside the tube. We explicitly calculate, in the high-temperature limit, the thermal average of the field square and the energy-momentum tensor.
Effective non-intercommutation of local cosmic strings at high collision speeds
Achucarro, Ana; de Putter, Roland
2006-01-01
We present evidence that Abrikosov-Nielsen-Olesen (ANO) strings pass through each other for very high speeds of approach due to a double intercommutation. In near-perpendicular collisions numerical simulations give threshold speeds bounded above by $\\sim 0.97 c$ for type I, and by $\\sim 0.90 c$ for deep type II strings. The second intercommutation occurs because at ultra high collision speeds, the connecting segments formed by the first intercommutation are nearly static and almost antiparall...
The B-L phase transition. Implications for cosmology and neutrinos
International Nuclear Information System (INIS)
We investigate the possibility that the hot thermal phase of the early universe is ignited in consequence of the B-L phase transition, which represents the cosmological realization of the spontaneous breaking of the Abelian gauge symmetry associated with B-L, the difference between baryon number B and lepton number L. Prior to the B-L phase transition, the universe experiences a stage of hybrid inflation. Towards the end of inflation, the false vacuum of unbroken B-L symmetry decays, which entails tachyonic preheating as well as the production of cosmic strings. Observational constraints on this scenario require the B-L phase transition to take place at the scale of grand unification. The dynamics of the B-L breaking Higgs field and the B-L gauge degrees of freedom, in combination with thermal processes, generate an abundance of heavy (s)neutrinos. These (s)neutrinos decay into radiation, thereby reheating the universe, generating the baryon asymmetry of the universe and setting the stage for the thermal production of gravitinos. The B-L phase transition along with the (s)neutrino-driven reheating process hence represents an intriguing and testable mechanism to generate the initial conditions of the hot early universe. We study the B-L phase transition in the full supersymmetric Abelian Higgs model, for which we derive and discuss the Lagrangian in arbitrary and unitary gauge. As for the subsequent reheating process, we formulate the complete set of Boltzmann equations, the solutions of which enable us to give a detailed and time-resolved description of the evolution of all particle abundances during reheating. Assuming the gravitino to be the lightest superparticle (LSP), the requirement of consistency between hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10GeV. As an alternative to gravitino dark matter, we consider the case of
The B-L phase transition. Implications for cosmology and neutrinos
Energy Technology Data Exchange (ETDEWEB)
Schmitz, Kai
2012-07-15
We investigate the possibility that the hot thermal phase of the early universe is ignited in consequence of the B-L phase transition, which represents the cosmological realization of the spontaneous breaking of the Abelian gauge symmetry associated with B-L, the difference between baryon number B and lepton number L. Prior to the B-L phase transition, the universe experiences a stage of hybrid inflation. Towards the end of inflation, the false vacuum of unbroken B-L symmetry decays, which entails tachyonic preheating as well as the production of cosmic strings. Observational constraints on this scenario require the B-L phase transition to take place at the scale of grand unification. The dynamics of the B-L breaking Higgs field and the B-L gauge degrees of freedom, in combination with thermal processes, generate an abundance of heavy (s)neutrinos. These (s)neutrinos decay into radiation, thereby reheating the universe, generating the baryon asymmetry of the universe and setting the stage for the thermal production of gravitinos. The B-L phase transition along with the (s)neutrino-driven reheating process hence represents an intriguing and testable mechanism to generate the initial conditions of the hot early universe. We study the B-L phase transition in the full supersymmetric Abelian Higgs model, for which we derive and discuss the Lagrangian in arbitrary and unitary gauge. As for the subsequent reheating process, we formulate the complete set of Boltzmann equations, the solutions of which enable us to give a detailed and time-resolved description of the evolution of all particle abundances during reheating. Assuming the gravitino to be the lightest superparticle (LSP), the requirement of consistency between hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10GeV. As an alternative to gravitino dark matter, we consider the case of
Bianchi Type-Ⅰ Cosmology with Cosmic String and Bulk Viscosity
Institute of Scientific and Technical Information of China (English)
王行翔
2003-01-01
Some locally rotationally symmetric Bianchi type-Ⅰ cosmological solutions for a cloud string with bulk viscosity are presented. In the first case, an equation of state p = kλ and the relation between metric potentials R = ASn are considered, and the solution represents shearing non-rotating model with the bulk viscosity ζ∝ p1/2, where p is the rest energy density of the cloud of strings with particles attached to them, λ is the tension density of the cloud of strings, ζ is the coeffcient of the bulk viscosity, R and S are only the functions of time t, while A and k are constant. In the second case, the constant coefficient of bulk viscosity is considered.
Abbasi, R; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Caballero-Mora, K S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Góra, D; Grant, D; Groß, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Johansson, H; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lünemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Mészáros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Naumann, U; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Pérez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Rädel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönherr, L; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van Eijndhoven, N; van der Drift, D; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zilles, A; Zoll, M
2012-01-01
The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above ~1 TeV using the IceCube array. This unique detector arrangement provides an opportunity for precision measurements of the cosmic ray energy spectrum and composition in the region of the knee and beyond. We present the results of a neural network analysis technique to study the cosmic ray composition and the energy spectrum from 1 PeV to 30 PeV using data recorded using the 40-string/40-station configuration of the IceCube Neutrino Observatory.
Henrot-Versillé, Sophie; Leroy, Nicolas; Plaszczynski, Stéphane; Arnaud, Nicolas; Bizouard, Marie-Anne; Cavalier, Fabien; Christensen, Nelson; Couchot, François; Franco, Samuel; Hello, Patrice; Huet, Dominique; Kasprzack, Marie; Perdereau, Olivier; Spinelli, Marta; Tristram, Matthieu
2014-01-01
The production of a primordial stochastic gravitational-wave background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the Cosmic Microwave Background (CMB) or the Baryon Acoustic Oscillations (BAO) can be used to set upper limits on the stochastic gravitational-wave background energy density $\\Omega_{GW}$ for frequencies above $10^{-15}$ Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-$\\ell$ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that $\\Omega_{GW}h_{0}^{2} < 3.8 \\times 10^{-6}$ at 95\\% confidence level for adiabatic initial conditions which improves over the previous limit by a factor 2.3. Assuming that the primordial gravitational waves have been produced by a network of cosmic strings, we have derived exclusion limits in th...
International Nuclear Information System (INIS)
Observations indicate that most of the universal matter is invisible and the gravitational constant G(t) maybe depends on time. A theory of the variational G (VG) is explored in this paper, naturally producing the useful dark components in the universe. We utilize the following observational data: lookback time data, model-independent gamma ray bursts, growth function of matter linear perturbations, type Ia supernovae data with systematic errors, CMB, and BAO, to restrict the unified model (UM) of dark components in VG theory. Using the best-fit values of the parameters with the covariance matrix, constraints on the variation of G are ((G)/(G0))z=3.5 ≅ 1.0015-0.0075+0.0071 and ((G)/(G))today ≅ -0.7252-2.3645+2.3645 x 10-13 year-1, with small uncertainties around the constants. The limit on the equation of state of dark matter is w0dm = 0.0072-0.0170+0.0170, assuming w0de = -1 in the unified model, and the dark energy is w0de = -0.9986-0.0011+0.0011, assuming w0dm = 0 a priori. The restrictions on the UM parameters are Bs = 0.7442-0.0132-0.0292+0.0137+0.0262 and α =0.0002-0.0209-0.0422+0.0206+0.0441 with 1σ and 2σ confidence level. In addition, the effects of a cosmic string fluid on the unified model in VG theory are investigated. In this case it is found that the Λ CDM (Ωs = 0, β = 0, and α = 0) is included in this VG-UM model at 1σ confidence level, and larger errors are given: Ωs = -0.0106-0.0305-0.0509+0.0312+0.0582 (dimensionless energy density of cosmic string), ((G)/(G0))z=3.5 ≅ 1.0008-0.0584+0.0620, and ((G)/(G))today ≅ -0.3496-26.3135+26.3135 x 10-13 year-1. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Lu, Jianbo; Xu, Yanfeng; Wu, Yabo [Liaoning Normal University, Department of Physics, Dalian (China)
2015-10-15
Observations indicate that most of the universal matter is invisible and the gravitational constant G(t) maybe depends on time. A theory of the variational G (VG) is explored in this paper, naturally producing the useful dark components in the universe. We utilize the following observational data: lookback time data, model-independent gamma ray bursts, growth function of matter linear perturbations, type Ia supernovae data with systematic errors, CMB, and BAO, to restrict the unified model (UM) of dark components in VG theory. Using the best-fit values of the parameters with the covariance matrix, constraints on the variation of G are ((G)/(G{sub 0})){sub z=3.5} ≅ 1.0015{sub -0.0075}{sup +0.0071} and ((G)/(G)){sub today} ≅ -0.7252{sub -2.3645}{sup +2.3645} x 10{sup -13} year{sup -1}, with small uncertainties around the constants. The limit on the equation of state of dark matter is w{sub 0dm} = 0.0072{sub -0.0170}{sup +0.0170}, assuming w{sub 0de} = -1 in the unified model, and the dark energy is w{sub 0de} = -0.9986{sub -0.0011}{sup +0.0011}, assuming w{sub 0dm} = 0 a priori. The restrictions on the UM parameters are B{sub s} = 0.7442{sub -0.0132-0.0292}{sup +0.0137+0.0262} and α =0.0002{sub -0.0209-0.0422}{sup +0.0206+0.0441} with 1σ and 2σ confidence level. In addition, the effects of a cosmic string fluid on the unified model in VG theory are investigated. In this case it is found that the Λ CDM (Ω{sub s} = 0, β = 0, and α = 0) is included in this VG-UM model at 1σ confidence level, and larger errors are given: Ω{sub s} = -0.0106{sub -0.0305-0.0509}{sup +0.0312+0.0582} (dimensionless energy density of cosmic string), ((G)/(G{sub 0})){sub z=3.5} ≅ 1.0008{sub -0.0584}{sup +0.0620}, and ((G)/(G)){sub today} ≅ -0.3496{sub -26.3135}{sup +26.3135} x 10{sup -13} year{sup -1}. (orig.)
D-term cosmic strings and Fayet-Iliopoulos terms from N=2 supergravity
International Nuclear Information System (INIS)
The authors extend the work of G. Dvali, R. Kallosh, and A. Van Proeyen (2004) by considering DF-term string solutions of d=4, N=1 supergravity with general Kaehler-Hodge target spaces, whereby the classical embedding of a class of these solutions into d=4, N=2 theories is discussed. It is shown how constant Fayet-Iliopoulos terms in N=1 can be engineered by gauging an appropriate U(1) isometry in the N=2 theory together with a truncation approach for the bosonic N=2 fields. The mechanism is illustrated by a simple example of an N=2 theory with one vector multiplet and one hypermultiplet. (HSI)
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Supergravity corrections due to the energy density of a right-handed sneutrino can generate a negative mass squared for the inflaton, flattening the inflaton potential and reducing the spectral index and inflaton energy density. For the case of D-term hybrid inflation, we show that the spectral index can be lowered from the conventional value n=0.98 to a value within the range favored by the latest WMAP analysis, n=0.951-0.019+0.015. The modified energy density is consistent with nonobservation of cosmic strings in the CMB if n<0.946. The WMAP lower bound on the spectral index implies that the D-term cosmic string contribution may be very close present CMB limits, contributing at least 5% to the CMB multipoles
International Nuclear Information System (INIS)
We study geometric quantum phases in the relativistic and non-relativistic quantum dynamics of a neutral particle with a permanent magnetic dipole moment interacting with two distinct field configurations in a cosmic string spacetime. We consider the local reference frames of the observers are transported via Fermi-Walker transport and study the influence of the non-inertial effects on the phase shift of the wave function of the neutral particle due to the choice of this local frame. We show that the wave function of the neutral particle acquires non-dispersive relativistic and non-relativistic quantum geometric phases due to the topology of the spacetime, the interaction between the magnetic dipole moment with external fields and the spin-rotation coupling. However, due to the Fermi-Walker reference frame, no phase shift associated to the Sagnac effect appears in the quantum dynamics of a neutral particle. We show that in the absence of topological defect, the contribution to the quantum phase due to the spin-rotation coupling is equivalent to the Mashhoon effect in non-relativistic dynamics. (orig.)
Vafa, Cumrun
1993-01-01
We review aspects of spacetime singularities from the view point of string theory. Examples considered include cosmological, cosmic string and black-hole singularities. We also discuss the consistency of viewing black-holes as excited states of fundamental strings (based on talk presented at Salamfest, March 1993, Trieste).
Seeking String Theory in the Cosmos
Copeland, Edmund J; Vachaspati, Tanmay
2011-01-01
We review the existence, formation and properties of cosmic strings in string theory, the wide variety of observational techniques that are being employed to detect them, and the constraints that current observations impose on string theory models.
Sanidas, S A; Stappers, B W
2012-01-01
We investigate the constraints that can be placed on the cosmic string tension by using the current Pulsar Timing Array limits on the stochastic gravitational wave background (SGWB). We have developed a code to compute the spectrum of gravitational waves (GWs) based on the widely accepted one-scale model. In its simplest form the one-scale model allows one to vary: (i) the string tension, G\\mu/c^2; (ii) the size of cosmic string loops relative to the horizon at birth, \\alpha; (iii) the spectral index of the emission spectrum, q; (iii) the cut-off in the emission spectrum, n_*; and (v) the intercommutation probability, p. The amplitude and slope of the spectrum in the nHz frequency range is very sensitive to these unknown parameters. We have also investigated the impact of more complicated scenarios with multiple initial loop sizes, in particular the 2-\\alpha models proposed in the literature and a log-normal distribution for \\alpha. We have computed the constraint on G\\mu/c^2 due to the limit on a SGWB impose...
Smolyaninov, Igor I; Smolyaninova, Vera N; Smolyaninov, Alexei I
2015-08-28
In the presence of an external magnetic field, cobalt nanoparticle-based ferrofluid forms a self-assembled hyperbolic metamaterial. The wave equation, which describes propagation of extraordinary light inside the ferrofluid, exhibits 2+1 dimensional Lorentz symmetry. The role of time in the corresponding effective three-dimensional Minkowski space-time is played by the spatial coordinate directed along the periodic nanoparticle chains aligned by the magnetic field. Here, we present a microscopic study of point, linear, planar and volume defects of the nanoparticle chain structure and demonstrate that they may exhibit strong similarities with such Minkowski space-time defects as magnetic monopoles, cosmic strings and the recently proposed space-time cloaks. Experimental observations of such defects are described. PMID:26217055
String Evolution with Friction
Martins, C.J.A.P.(Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, Porto, 4150-762, Portugal); Shellard, E. P. S.
1995-01-01
We study the effects of friction on the scaling evolution of string networks in condensed matter and cosmological contexts. We derive a generalized `one-scale' model with the string correlation length $L$ and velocity $v$ as dynamical variables. In non-relativistic systems, we obtain a well-known $L\\propto t^{1/2}$ law, showing that loop production is important. For electroweak cosmic strings, we show transient damped epoch scaling with $L\\propto t^{5/4}$ (or, in the matter era, $L\\propto t^{...
Sen, Ashoke
1997-01-01
Type IIB string theory admits a BPS configuration in which three strings (of different type) meet at a point. Using this three string configuration we construct a string network and study its properties. In particular we prove supersymmetry of this configuration. We also consider string lattices, which can be used to construct BPS states in toroidally compactified string theory.
Do Global String Loops Collapse to Form Black Holes?
Fort, Joaquim; Vachaspati, Tanmay(Physics Department, Arizona State University, Tempe, Arizona 85287, U.S.A.)
1993-01-01
Hawking has shown that the emission of gravitational radiation cannot prevent circular loops of gauged cosmic strings from collapsing into black holes. Here we consider the corresponding question for global strings: can Goldstone boson emission prevent circular loops of global cosmic strings from forming black holes? Our results show that for every value of the string tension there is a certain critical size below which the circular loop does not collapse to form a black hole. For GUT scale s...
Global strings in five-dimensional supergravity
Marui, Miho
2015-01-01
We show the existence of solitonic solutions of five-dimensional supergravity, which can be interpreted as global cosmic strings in our universe. They possess the same mathematical structure as the stringy cosmic strings studied by Greene, Shapere, Vafa and Yau, while the size of the extra space and the value of the extra-space component of the gauge field vary from place to place around the string in our model. We also show that supersymmetry is partially broken in the presence of the global strings.
Abbasi, R.; Abdou, Yasser; Ackermann, M; Adams, J.; Aguilar, JA; Ahlers, M.; Altmann, D; Andeen, K; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, SW; Baum, V.; Bay, R.; Beattie, K
2012-01-01
The mass composition of high energy cosmic rays depends on their production, acceleration, and propagation. The study of cosmic ray composition can therefore reveal hints of the origin of these particles. At the South Pole, the IceCube Neutrino Observatory is capable of measuring two components of cosmic ray air showers in coincidence: the electromagnetic component at high altitude (2835 m) using the IceTop surface array, and the muonic component above ~1 TeV using the IceCube array. This uni...
International Nuclear Information System (INIS)
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.)
The mass spectra, hierarchy and cosmology of B-L MSSM heterotic compactifications
International Nuclear Information System (INIS)
The matter spectrum of the MSSM, including three right-handed neutrino supermultiplets and one pair of Higgs-Higgs conjugate superfields, can be obtained by compactifying the E8 x E8 heterotic string and M-theory on Calabi-Yau manifolds with specific SU(4) vector bundles. These theories have the standard model gauge group augmented by an additional gauged U(1)B-L. Their minimal content requires that the B-L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed neutrino. In previous papers, we presented the results of a quasi-analytic renormalization group analysis showing that B-L gauge symmetry is indeed radiatively broken with an appropriate B-L/electroweak hierarchy. In this paper, we extend these results by 1) enlarging the initial parameter space and 2) explicitly calculating all renormalization group equations numerically. The regions of the initial parameter space leading to realistic vacua are presented and the B-L/electroweak hierarchy computed over these regimes. At representative points, the mass spectrum for all particles and Higgs fields is calculated and shown to be consistent with present experimental bounds. Some fundamental phenomenological signatures of a non-zero right-handed neutrino expectation value are discussed, particularly the cosmology and proton lifetime arising from induced lepton and baryon number violating interactions
Global strings in five-dimensional supergravity
Marui, Miho; Shiraishi, Kiyoshi
2015-01-01
We show the existence of solitonic solutions of five-dimensional supergravity, which can be interpreted as global cosmic strings in our universe. They possess the same mathematical structure as the stringy cosmic strings studied by Greene, Shapere, Vafa and Yau, while the size of the extra space and the value of the extra-space component of the gauge field vary from place to place around the string in our model. We also show that supersymmetry is partially broken in the presence of the global...
Baryon production from embedded metastable strings
Karouby, Johanna
2013-01-01
We quantify the baryon anti-baryon production generated by a metastable cosmic string, similar to the embedded pion string. More precisely, we study skyrmion production mediated by instantons generated by a pion-like metastable string in contact with a thermal bath, and interpret these Skyrmions as baryons. As shown in a previous work, the core of such a metastable string can melt due to quantum tunneling in the charged field direction. The specific configuration of our string containing 4 scalar fields out of equilibrium in contact with a thermal bath is shown to yield skyrmion production with partial or integer winding number. In this work, we describe and quantify this skyrmion production per unit length of the string. We also evaluate the skyrmion-anti skyrmions production by a dense string network by invoking similarity with the Skyrmion production in a phase transition.
Indian Academy of Sciences (India)
C P Burgess
2004-12-01
The inflationary paradigm provides a robust description of the peculiar initial conditions which are required for the success of the hot Big Bang model of cosmology, as well as of the recent precision measurements of temperature fluctuations within the cosmic microwave background. Furthermore, the success of this description indicates that inflation is likely to be associated with physics at energies considerably higher than the weak scale, for which string theory is arguably our most promising candidate. These observations strongly motivate a detailed search for inflation within string theory, although it has (so far) proven to be a hunt for a fairly elusive quarry. This article summarizes some of the recent efforts along these lines, and draws some speculative conclusions as to what the difficulty in finding inflation might mean.
International Nuclear Information System (INIS)
This article is devoted to a nontechnical review on the present status of string theory towards an ultimate unification of all fundamental interactions including gravity. In particular, we emphasize the importance of string theory as a new theoretical framework in which the long-standing conflict between quantum theory and general relativity is resolved. (author)
Marino Beiras, Marcos
2001-01-01
We give an overview of the relations between matrix models and string theory, focusing on topological string theory and the Dijkgraaf--Vafa correspondence. We discuss applications of this correspondence and its generalizations to supersymmetric gauge theory, enumerative geometry and mirror symmetry. We also present a brief overview of matrix quantum mechanical models in superstring theory.
Bali, G S; Lippert, T; Neff, H; Prkacin, Z; Schilling, K; Bali, Gunnar S; Dussel, Thomas; Lippert, Thomas; Neff, Hartmut; Prkacin, Zdravko; Schilling, Klaus
2006-01-01
We numerically investigate the transition of the static quark-antiquark string into a static-light meson-antimeson system. Improving noise reduction techniques, we are able to resolve the signature of string breaking dynamics for Nf=2 lattice QCD at zero temperature. We discuss the lattice techniques used and present results on energy levels and mixing angle of the static two-state system. We visualize the action density distribution in the region of string breaking as a function of the static colour source-antisource separation. The results can be related to properties of quarkonium systems.
LRS Bianchi type-I string cosmological models in f (R, T) gravity
Kanakavalli, T.; Ananda Rao, G.
2016-07-01
Spatially homogeneous and anisotropic LRS Bianchi type-I space time is investigated in the presence of cosmic string source in a modified theory of gravitation formulated by Harko et al. (Phys. Rev. D 84:024020, 2011). We have solved the field equations using the equations of state for strings and presented cosmological models which describe geometric string, Takabayasi string and Reddy string in this particular theory. Some physical and kinematical parameters of the models are computed and discussed their physical significance.
String cosmology. Large-field inflation in string theory
International Nuclear Information System (INIS)
This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index ns and the fractional tensor mode power r. Hence, we focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.
Numerical simulation of bosonic-superconducting-string interactions
Energy Technology Data Exchange (ETDEWEB)
Laguna, P. (Department of Physics and Atomspheric Science, Drexel University, Philadelphia, Pennsylvania 19104 (USA)); Matzner, R.A. (Department of Physics, University of Texas, Austin, Texas 78712 (USA) Center for Relativity, The University of Texas at Austin, Austin, Texas 78712 (USA))
1990-03-15
Numerical simulations show that bosonic superconducting U(1) gauge cosmic strings interact by reconnecting and chopping off in a fashion similar to nonconducting strings. Cancellation of the electromagnetic current occurs when, in one of the strings, the direction of the U(1) gauge magnetic field is opposite to the electromagnetic current flow. Electric charge accumulates on the segments of the reconnected strings where the current is discontinuous or vanishes. A {ital virtual} {ital photon} appears after the collision and intercommutation, and a bubble of electromagnetic radiation emerges as the currents in the reconnected strings equalize. These phenomena suggest new possible mechanisms for void production in the large-scale distribution of galaxies.
Mirage in the sky: Nonthermal dark matter, gravitino problem, and cosmic ray anomalies
International Nuclear Information System (INIS)
Recent anomalies in cosmic rays could be due to dark matter annihilation in our galaxy. In order to get the required large cross section to explain the data while still obtaining the right relic density, we rely on a nonstandard thermal history between dark matter freeze out and big-bang nucleosynthesis. We show that through a reheating phase from the decay of a heavy moduli or even the gravitino, we can produce the right relic density of dark matter if its self-annihilation cross section is large enough. In addition to fitting the recent data, this scenario solves the cosmological moduli and gravitino problems. We illustrate this mechanism with a specific example in the context of U(1)B-L extended minimal supersymmetric standard model where supersymmetry is broken via mirage mediation. These string motivated models naturally contain heavy moduli decaying to the gravitino, whose subsequent decay to the LSP can reheat the Universe at a low temperature. The right-handed sneutrino and the B-L gaugino can both be viable dark matter candidates with a large cross section. They are leptophilic because of B-L charges. We also show that it is possible to distinguish the nonthermal from the thermal scenario (using Sommerfeld enhancement) in direct detection experiments for certain regions of parameter space.
Generalised hyperbolicity in spacetimes with string-like singularities
Sanchez, Yafet Sanchez
2016-01-01
In this paper we present well-posedness results of the wave equation in $H^{1}$ for spacetimes that contain string-like singularities. These results extend a framework able to characterise gravitational singularities as obstruction to the dynamics of test fields rather than point particles. In particular, we discuss spacetimes with cosmic strings and the relation of our results to the Strong Cosmic Censorship Conjecture.
Scaling configurations of cosmic superstring networks and their cosmological implications
Pourtsidou, Alkistis; Avgoustidis, Anastasios; Copeland, Edmund J.; Pogosian, Levon; Steer, Daniele A.
2010-01-01
We study the cosmic microwave background temperature and polarisation spectra sourced by multi-tension cosmic superstring networks. First we obtain solutions for the characteristic length scales and velocities associated with the evolution of a network of F-D strings, allowing for the formation of junctions between strings of different tensions. We find two distinct regimes describing the resulting scaling distributions for the relative densities of the different types of strings, depending o...
New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.
Intended primarily for use by instrumental music teachers who do not have a major concentration in strings, this guide provides pertinent basic resources, materials, teaching--learning expectation, and a general overall guide to achievement levels at various stages of development. Discussions are presented of Choosing the Proper Method Book,…
Spontaneous B-L breaking as the origin of the hot early universe
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.; Domcke, V.; Schmitz, K.
2012-03-15
The decay of a false vacuum of unbroken B-L symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase yields hybrid inflation, ending in tachyonic preheating. The dynamics of the B - L breaking Higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy, baryon asymmetry and gravitino dark matter. We study the phase transition for the full supersymmetric Abelian Higgs model. For the subsequent reheating process we give a detailed time-resolved description of all particle abundances. The competition of cosmic expansion and entropy production leads to an intermediate period of constant 'reheating' temperature, during which baryon asymmetry and dark matter are produced. Consistency of hybrid inflation, leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses, in particular a lower bound on the gravitino mass of 10 GeV.
Periwal, Vipul; Tafjord, Oyvind
1998-01-01
String configurations have been identified in compactified Matrix theory at vanishing string coupling. We show how the interactions of these strings are determined by the Yang-Mills gauge field on the worldsheet. At finite string coupling, this suggests the underlying dynamics is not well-approximated as a theory of strings. This may explain why string perturbation theory diverges badly, while Matrix string perturbation theory presumably has a perturbative expansion with properties similar to...
String Field Theory of Noncritical Strings
Ishibashi, Nobuyuki; Kawai, Hikaru
1993-01-01
We construct the Hamiltonian operator of the string field theory for $c=0$ string theory. It describes how strings evolve in the coordinate frame, which is defined by using the geodesic distance on the worldsheet. The Hamiltonian consists of three-string interaction terms and a tadpole term. We show that one can derive the loop amplitudes of $c=0$ string theory from this Hamiltonian.
Probing Cosmic Superstrings with Gravitational Waves
Sousa, Lara
2016-01-01
We compute the stochastic gravitational wave background generated by cosmic superstrings using a semi-analytical velocity-dependent model to describe their dynamics. We show that heavier string types may leave distinctive signatures on the stochastic gravitational wave background spectrum within the reach of present and upcoming gravitational wave detectors. We examine the physically motivated scenario in which the physical size of loops is determined by the gravitational backreaction scale and use NANOGRAV data to derive a conservative constraint of $G\\mu_F<3.2 \\times 10^{-9}$ on the tension of fundamental strings. We demonstrate that approximating the gravitational wave spectrum generated by cosmic superstring networks using the spectrum generated by ordinary cosmic strings with reduced intercommuting probability (which is often done in the literature) leads, in general, to weaker observational constraints on $G\\mu_F$. We show that the inclusion of heavier string types is required for a more accurate cha...
Scaling of multitension cosmic superstring networks
International Nuclear Information System (INIS)
Brane inflation in superstring theory ends when branes collide, initiating the hot big bang. Cosmic superstrings are produced during the brane collision. The cosmic superstrings produced in a D3-brane-antibrane inflationary scenario have a spectrum: (p,q) bound states of p fundamental (F) strings and q D-strings, where p and q are coprime. By extending the velocity-dependent one-scale network evolution equations for Abelian Higgs cosmic strings to allow a spectrum of string tensions, we construct a coupled (infinite) set of equations for strings that interact through binding and self-interactions. We apply this model to a network of (p,q) superstrings. Our numerical solutions show that (p,q) networks rapidly approach a stable scaling solution. We also extract the relative densities of each string type from our solutions. Typically, only a small number of the lowest tension states are populated substantially once scaling is reached. The model we study also has an interesting new feature: the energy released in (p,q) string binding is by itself adequate to allow the network to reach scaling. This result suggests that the scaling solution is robust. To demonstrate that this result is not trivial, we show that choosing a different form for string interactions can lead to network frustration
String Theory and the Shape of the Universe
McInnes, B
2004-01-01
Much effort has been expended recently on attempts to determine the topology of the Universe by means of direct astronomical evidence. However, little is known about how theory, in particular, string theory, constrains cosmic topology. Here we show that if our world is a brane-world in five-dimensional anti-de Sitter spacetime -- an assumption which is itself well-motivated from the string point of view -- then string theory is in conflict with the "dodecahedral" cosmology proposed recently. We discuss this as an example demonstrating the ability of string theory to make specific statements about global spacetime structure.
Polyakov, A. M.
2008-01-01
In this article, prepared for the book "The birth of string theory", I recall the sequence of ideas which led to non-critical strings and gauge/strings duality. I also comment on some promising future directions.
Cosmic censorship and the dilaton
International Nuclear Information System (INIS)
We investigate extremal electrically charged black holes in Einstein-Maxwell-dilaton theory with a cosmological constant inspired by string theory. These solutions are not static, and a timelike singularity eventually appears which is not surrounded by an event horizon. This suggests that cosmic censorship may be violated in this theory
Academic Training: String Theory for Pedestrians
2007-01-01
2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 29, 30, 31 January 2007, from 11:00 to 12:00 Main Auditorium, bldg. 500 on 29 and 30 January, TH Auditorium, Bldg 4, 3-006, on 31 January String Theory for Pedestrians B. ZWIEBACH, MIT, Cambridge, USA In this 3-lecture series I will discuss the basics of string theory, some physical applications, and the outlook for the future. I will begin with the main concepts of the classical theory and the application to the study of cosmic superstrings. Then I will turn to the quantum theory and discuss applications to the investigation of hadronic spectra and the recently discovered quark-gluon plasma. I will conclude with a sketch of string models of particle physics and showing some avenues that may lead to a complete formulation of string theory.
Bowick, Mark J.
1992-01-01
These are lecture notes for the 1992 Erice Workshop on String Quantum Gravity and Physics at the Planck Energy Scale. In this talk a review of earlier work on finite temperature strings was presented. Several topics were covered, including the canonical and microcanonical ensemble of strings, the behavior of strings near the Hagedorn temperature as well as speculations on the possible phases of high temperature strings. The connection of the string ensemble and, more generally, statistical sy...
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...
Towards a kinetic theory of strings
Vanchurin, Vitaly
2011-01-01
We study the dynamics of strings by means of a distribution function $f({\\bf A}, {\\bf B}, {\\bf x}, t)$ defined on a 9+1D phase space, where ${\\bf A}$ and ${\\bf B}$ are the correlation vectors of right- and left-moving waves. We derive a transport equation (an analogous to Boltzmann transport equation for particles) that governs the evolution of long strings with Nambu-Goto dynamics as well as reconnections taken into account. We also derive a system of coupled transport equations (an analogous to BBGKY hierarchy for particles) which can simultaneously describe long strings $\\tilde{f}({\\bf A}, {\\bf B}, {\\bf x}, t)$ as well as simple loops $\\mathring{f}({\\bf A}, {\\bf B}, {\\bf x}, t)$ made out of four correlation vectors. The formalism can be used to study non-linear dynamics of fundamental strings, D-brane strings or field theory strings. For example, the complicated semi-scaling behavior of cosmic strings translates into a simple solution of the transport system at small energy densities.
R-parity Conserving Minimal SUSY $B-L$ Model
Okada, Nobuchika
2016-01-01
We propose a simple gauged U(1)$_{B-L}$ extension of the minimal supersymmetric Standard Model (MSSM), where R-parity is conserved as usual in the MSSM. The global $B-L$ (baryon number minus lepton number) symmetry in the MSSM is gauged and three MSSM gauge-singlet chiral multiplets with a unit $B-L$ charge are introduced, ensuring the model free from gauge and gravitational anomalies. We assign an odd R-parity for two of the new chiral multiplets and hence they are identified with the right-handed neutrino superfields, while an even R-parity is assigned to the other one ($\\Phi$). The scalar component of $\\Phi$ plays the role of a Higgs field to break the U(1)$_{B-L}$ symmetry through its negative mass squared, which is radiatively generated by the renormalization group running of soft supersymmetry (SUSY) breaking parameters from a high energy. This radiative U(1)$_{B-L}$ symmetry breaking leads to its breaking scale being at the TeV naturally. Because of our novel R-parity assignment, three light neutrinos ...
Unifying the electroweak and B-L interactions
Dong, P V
2015-01-01
We argue that the gauge symmetry which includes SU(3)_L as a higher weak-isospin symmetry is manifestly given by SU(3)_C\\otimes SU(3)_L\\otimes U(1)_X\\otimes U(1)_N, where the last two factors determine the electric charge and B-L, respectively. This theory not only provides a consistent unification of the electroweak and B-L interactions, but also gives insights in dark matter, neutrino masses, and inflation. The dark matter belongs to a class of new particles that have wrong B-L numbers, and is stabilized due to a newly-realized W-parity as residual gauge symmetry. The B-L breaking field is important to define the W-parity, seesaw scales, and inflaton. Furthermore, the number of fermion generations and the electric charge quantization are explained naturally. We also show that the previous 3-3-1 models are only an effective theory as the B-L charge and the unitarity argument are violated. This work substantially generalizes our recently-proposed 3-3-1-1 model.
International Nuclear Information System (INIS)
The hystory, main ideas, motivations for developing string field theory are reported. The connection between the first and second quantization for a system of point particles, strings and membranes is analysed. The main features of superstring theory are discussed. Free bosonic strings and string field algebra are considered
Constraint Reasoning Over Strings
Koga, Dennis (Technical Monitor); Golden, Keith; Pang, Wanlin
2003-01-01
This paper discusses an approach to representing and reasoning about constraints over strings. We discuss how many string domains can often be concisely represented using regular languages, and how constraints over strings, and domain operations on sets of strings, can be carried out using this representation.
Bursa, Francis; Kroyter, Michael
2010-01-01
String field theory is a candidate for a full non-perturbative definition of string theory. We aim to define string field theory on a space-time lattice to investigate its behaviour at the quantum level. Specifically, we look at string field theory in a one dimensional linear dilaton background. We report the first results of our simulations.
Polchinski, Joseph
1994-01-01
The first part is an introduction to conformal field theory and string perturbation theory. The second part deals with the search for a deeper answer to the question posed in the title. Contents: 1. Conformal Field Theory 2. String Theory 3. Vacua and Dualities 4. String Field Theory or Not String Field Theory 5. Matrix Models
Mirage in the Sky: Non-thermal Dark Matter, Gravitino Problem, and Cosmic Ray Anomalies
Dutta, Bhaskar; Sinha, Kuver
2009-01-01
Recent anomalies in cosmic rays could be due to dark matter annihilation in our galaxy. In order to get the required large cross-section to explain the data while still obtaining the right relic density, we rely on a non standard thermal history between dark matter freeze-out and Big-Bang Nucleosynthesis (BBN). We show that through a reheating phase from the decay of a heavy moduli or even the gravitino, we can produce the right relic density of dark matter if its self-annihilation cross-section is large enough. In addition to fitting the recent data, this scenario solves the cosmological moduli and gravitino problems. We illustrate this mechanism with a specific example in the context of U(1)_{B-L} extended MSSM where supersymmetry is broken via mirage mediation. These string motivated models naturally contain heavy moduli decaying to the gravitino, whose subsequent decay to the LSP can reheat the universe at a low temperature. The right-handed sneutrino and the B-L gaugino can both be viable dark matter can...
Majorana Dark matter with B+L gauge symmetry
Chao, Wei; Guo, Huai-Ke; Zhang, Yongchao
2016-01-01
We present a new model that extends the Standard Model (SM) with the local B+L symmetry, and point out that the lightest new fermion $\\zeta$, introduced to cancel anomalies and stabilized automatically by the B+L symmetry, can serve as the cold dark matter candidate. We study constraints on the model from Higgs measurements, electroweak precision measurements as well as the relic density and direct detections of the dark matter. Numerical results reveal that the pseudo-vector coupling of $\\ze...
Baryogenesis via B- L violation in SO(10) unified models
Buccella, F.; Mangano, G.; Masiero, A.; Rosa, L.
1994-01-01
We discuss the problem of baryon number generation in the framework of a class of SO(10) grand unified models with an intermediate mass scale. In these theories the neutrino mass spectrum allows for the τ neutrino to be a good candidate for the hot component of the dark matter and, at the same time, an implementation of the MSW mechanism is possible. We show that an adequate matter-antimatter asymmetry is achievable through the interplay of B- L violating decays of scalar bosons into massive right-handed neutrinos with the anomalous B+ L violating processes mediated by sphalerons.
Classically conformal radiative neutrino model with gauged B - L symmetry
Okada, Hiroshi; Orikasa, Yuta
2016-09-01
We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.
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 ...
International Nuclear Information System (INIS)
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
Tong, David
2009-01-01
This is a one semester course on bosonic string theory aimed at beginning graduate students. The lectures assume a working knowledge of quantum field theory and general relativity. Contents: 1. The Classical String 2. The Quantum String 3. Open Strings and D-Branes 4. Introducing Conformal Field Theory 5. The Polyakov Path Integral and Ghosts 6. String Interactions 7. The Low-Energy Effective Action 8. Compactification and T-Duality
Probing classically conformal $B-L$ model with gravitational waves
Jinno, Ryusuke
2016-01-01
We study the cosmological history of the classical conformal $B-L$ gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. Especially, we consider the thermal phase transition of the U$(1)_{B-L}$ symmetry in the early universe and resulting gravitational-wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) U$(1)_{B-L}$ is broken after the reheating, (2) the $B-L$ gauge coupling does not blow up below the Planck scale, (3) the thermal phase transition completes in almost all the patches in the universe, the gravitational wave spectrum can be as large as $\\Omega_{\\rm GW} \\sim 10^{-8}$ at the frequency $f \\sim 0.01$-$1$Hz for some model parameters, and a vast parameter region can be tested by future interferometer experiments such as eLISA, LISA, BBO and DECIGO.
Cosmological Consequences of String Axions
International Nuclear Information System (INIS)
Axion fluctuations generated during inflation lead to isocurvature and non-Gaussian temperature fluctuations in the cosmic microwave background radiation. Following a previous analysis for the model independent string axion we consider the consequences of a measurement of these fluctuations for two additional string axions. We do so independent of any cosmological assumptions except for the axions being massless during inflation. The first axion has been shown to solve the strong CP problem for most compactifications of the heterotic string while the second axion, which does not solve the strong CP problem, obeys a mass formula which is independent of the axion scale. We find that if gravitational waves interpreted as arising from inflation are observed by the PLANCK polarimetry experiment with a Hubble constant during inflation of Hinf ∼> 1013 GeV the existence of the first axion is ruled out and the second axion cannot obey the scale independent mass formula. In an appendix we quantitatively justify the often held assumption that temperature corrections to the zero temperature QCD axion mass may be ignored for temperatures T ∼QCD
Spin-String Interaction in QCD Strings
Vyas, Vikram
2007-01-01
I analyse the problem of introducing the spin of the quark and the antiquark in effective QCD strings from the point of view of the Wilson loop for a spin-half particle, or the Super Wilson loop. A string representation of the Super Wilson loop is obtained starting from an effective string representation of a Wilson Loop. The action obtained in this manner is invariant under a worldline supersymmetry and has a boundary term which contains the spin-string interaction. For rectangular loops the spin-string interaction vanishes. If an allowance is made for the finite thickness of the flux tube that is being modelled by a string then we obtain a spin-spin interaction which falls as the fifth power of the distance. Such a term was previously suggested by Kogut and Parisi in the context of a flux-tube model of confinement.
String-String Duality in Ten Dimensions
Hull, C. M.
1995-01-01
The heterotic string occurs as a soliton of the type I superstring in ten dimensions, supporting the conjecture that these two theories are equivalent. The conjecture that the type IIB string is self-dual, with the strong coupling dynamics described by a dual type IIB theory, is supported by the occurrence of the dual string as a Ramond-Ramond soliton of the weakly-coupled theory.
Closed String Amplitudes from Gauge Fixed String Field Theory
Drukker, Nadav
2002-01-01
Closed string diagrams are derived from cubic open string field theory using a gauge fixed kinetic operator. The basic idea is to use a string propagator that does not generate a boundary to the world sheet. Using this propagator and the closed string vertex, the moduli space of closed string surfaces is covered, so closed string scattering amplitudes should be reproduced. This kinetic operator could be a gauge fixed form of the string field theory action around the closed string vacuum.
Kleban, Matthew; Lawrence, Albion; Shenker, Stephen
2000-01-01
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 bo...
Dielectric Fundamental Strings in Matrix String Theory
Brecher, Dominic; Janssen, Bert; Lozano, Yolanda
2001-01-01
Matrix string theory is equivalent to type IIA superstring theory in the light-cone gauge, together with extra degrees of freedom representing D-brane states. It is therefore the appropriate framework in which to study systems of multiple fundamental strings expanding into higher-dimensional D-branes. Starting from Matrix theory in a weakly curved background, we construct the linear couplings of closed string fields to type IIA Matrix strings. As a check, we show that at weak coupling the res...
Inflation in string theory confronts data
International Nuclear Information System (INIS)
Following the 2015 Planck release, we briefly comment on the status and some ongoing opportunities in the interface between inflationary cosmology, string theory, and CMB (Cosmic Microwave Background) data. The constraints in the r-ns plane introduce a new parameter into inflationary cosmology relative to the simplest quadratic inflation model, in a direction which fits well with couplings to heavy fields as occurs in string theory. The precision of the data permits further searches for and constraints on additional model-dependent features, such as oscillatory N-spectra, a program requiring specific theoretically motivated shapes. Since the perturbations can easily be affected by additional sectors and couplings, null results can usefully bound such contributions. We also review the broader lessons string theory has contributed to our understanding of primordial inflation, and close with some approaches to a more complete framework. (author)
Primordial magnetic fields from the string network
Horiguchi, Kouichirou; Ichiki, Kiyotomo; Sugiyama, Naoshi
2016-08-01
Cosmic strings are a type of cosmic defect formed by a symmetry-breaking phase transition in the early universe. Individual strings would have gathered to build a network, and their dynamical motion would induce scalar-, vector-, and tensor-type perturbations. In this paper, we focus on the vector mode perturbations arising from the string network based on the one scale model and calculate the time evolution and the power spectrum of the associated magnetic fields. We show that the relative velocity between photon and baryon fluids induced by the string network can generate magnetic fields over a wide range of scales based on standard cosmology. We obtain the magnetic field spectrum before recombination as aB(k,z)~4×10Gμ/1k)3.5 gauss on super-horizon scales, and aB(k,z)~2.4×10Gμ/1k)2.5 gauss on sub-horizon scales in co-moving coordinates. This magnetic field grows up to the end of recombination, and has a final amplitude of approximately B~10Gμ gauss at the k~1 Mpc scale today. This field might serve as a seed for cosmological magnetic fields.
International Nuclear Information System (INIS)
We incorporate the string theory into the number theoretic formulation based on arithmetic geometry. The string theory is generalized p-adically and interpreted on an arithmetic surface. A p-adic multi-loop scattering amplitude is constructed. (orig.)
Bonora, L.; Maccaferri, C.; Santos, R. J. Scherer; Tolla, D. D.
2005-01-01
In this letter we show that vacuum string field theory contains exact solutions that can be interpreted as macroscopic fundamental strings. They are formed by a condensate of infinitely many completely space-localized solutions (D0-branes).
Relativistic classical strings. II
International Nuclear Information System (INIS)
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.)
Majorana Dark matter with B+L gauge symmetry
Chao, Wei; Zhang, Yongchao
2016-01-01
We present a new model that extends the Standard Model (SM) with the local B+L symmetry, and point out that the lightest new fermion $\\zeta$, introduced to cancel anomalies and stabilized automatically by the B+L symmetry, can serve as the cold dark matter candidate. We study constraints on the model from Higgs measurements, electroweak precision measurements as well as the relic density and direct detections of the dark matter. Numerical results reveal that the pseudo-vector coupling of $\\zeta$ with $Z$ and the Yukawa coupling with the SM Higgs are highly constrained by the latest results of LUX, while there are viable parameter space that could satisfy all the constraints and give testable predictions.
Asymmetric Gepner models III. B-L lifting
Energy Technology Data Exchange (ETDEWEB)
Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands); Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); IMAPP, Radboud Universiteit, Nijmegen (Netherlands)
2011-06-21
In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1){sub B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10)xE{sub 8} part of the CFT. However, it can only yield chiral spectra if the 'internal' sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.
Asymmetric Gepner Models III. B-L Lifting
Gato-Rivera, B
2010-01-01
In the same spirit as heterotic weight lifting, B-L lifting is a way of replacing the superfluous and ubiquitous U(1)_{B-L} with something else with the same modular properties, but different conformal weights and ground state dimensions. This method works in principle for all variants of (2,2) constructions, such as orbifolds, Calabi-Yau manifolds, free bosons and fermions and Gepner models, since it only modifies the universal SO(10) x E_8 part of the CFT. However, it can only yield chiral spectra if the ``internal" sector of the theory provides a simple current of order 5. Here we apply this new method to Gepner models. Including exceptional invariants, 86 of them have the required order 5 simple current, and 69 of these yield chiral spectra. Three family spectra occur abundantly.
Two Nucleon (B-L)-Conserving Reactions Involving Tau Leptons
Bryman, Douglas
2014-01-01
Tau lepton emission in two-nucleon disappearance reactions from within nuclei which conserve baryon number minus lepton number (B-L) is considered. It is shown that some existing limits on proton decay channels and two-nucleon disappearance reactions resulting in electrons and muons can be applied to $\\Delta B=\\Delta L=2$ decays involving $\\tau$ leptons. For the two-nucleon disappearance channel $np\\to\\tau^+ \\overline\
Nonrelativistic closed string theory
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 tra...
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.
Schmidhuber, Christof
2000-01-01
What are strings made of? The possibility is discussed that strings are purely mathematical objects, made of logical axioms. More precisely, proofs in simple logical calculi are represented by graphs that can be interpreted as the Feynman diagrams of certain large-N field theories. Each vertex represents an axiom. Strings arise, because these large-N theories are dual to string theories. These ``logical quantum field theories'' map theorems into the space of functions of two parameters: N and...
Bianchi type-V string cosmological models in general relativity
Indian Academy of Sciences (India)
Anil Kumar Yadav; Vineet Kumar Yadav; Lallan Yadav
2011-04-01
Bianchi type-V string cosmological models in general relativity are investigated. To get the exact solution of Einstein’s ﬁeld equations, we have taken some scale transformations used by Camci et al [Astrophys. Space Sci. 275, 391 (2001)]. It is shown that Einstein’s ﬁeld equations are solvable for any arbitrary cosmic scale function. Solutions for particular forms of cosmic scale functions are also obtained. Some physical and geometrical aspects of the models are discussed.
Cosmological constraints on string scale and coupling arising from tachyonic instability
International Nuclear Information System (INIS)
We demonstrate that string motivated inflation ending via tachyonic instability leaves a detectable imprint on the cosmic microwave background (CMB) radiation by virtue of the excitation of non-gaussian gravitational fluctuations. The present WMAP bound on non-gaussianity is shown to constrain the string scale by MS/MP ≤ 10-4 for string coupling gss ∼ 10-9 for MS/MP-3. This case may soon be ruled out by the forthcoming CMB non-gaussinianity bounds
Chung, D Y; Chung, Ding-Yu; Krasnoholovets, Volodymyr
2005-01-01
We present the cosmic organism theory in which all visible and invisible matter has different cosmic genetic expressions. The cosmic gene includes codes for the object structure and the space structure. The cosmic digital code for the object structure consists of full object (1, 2, and 3 for particle, string, and membrane, respectively) and empty object (0) as anti de Sitter space (AdS). The tessellation lattice of empty objects is tessellattice. The decomposition of a full object in tessellattice results in the AdS/CFT (conformal field theory) duality. The digital code for the object structure accounts for the AdS/CFT duality, the dS/bulk duality, and gravity. The digital code for the space structure consists of 1 and 0 for attachment space and detachment space, respectively. Attachment space attaches to object permanently at zero speed or reversibly at the speed of light. Detachment space detaches from the object irreversibly at the speed of light. The combination of attachment space and detachment space re...
International Nuclear Information System (INIS)
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.)
International Nuclear Information System (INIS)
After the termination of perturbative QCD tree evolution, colourless clusters are formed. Similarly, after the first generation cuts in the (classical) Artru-Mennessier string model, disconnected lengths of string result. The mass spectra of clusters and first generation strings are similar, and the similarity extends to the rapidity distributions as a function of mass. (author)
Cardona, Biel; Pons, Josep M
2016-01-01
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.
de Boer, Jan
2002-01-01
An overview of some of the developments in string theory over the past two years is given, focusing on four topics: realistic (standard model like) models from string theory, geometric engineering and theories with fluxes, the gauge theory-gravity correspondence, and time dependent backgrounds and string theory. Plenary talk at ICHEP'02, Amsterdam, July 24-31, 2002.
Closed String Cohomology in Open String Field Theory
Moeller, Nicolas; Sachs, Ivo
2010-01-01
We show that closed string states in bosonic string field theory are encoded in the cyclic cohomology of cubic open string field theory (OSFT) which, in turn, classifies the deformations of OSFT. This cohomology is then shown to be independent of the open string background. Exact elements correspond to closed string gauge transformations, generic boundary deformations of Witten's 3-vertex and infinitesimal shifts of the open string background. Finally it is argued that the closed string cohom...
Gubser, S S
2003-01-01
I argue that string creation may have played a role in reheating the universe after inflation. For strings in four dimensions that arise from branes wrapping cycles in the extra dimensions, estimates from effective field theory show that the string tension need only fall a couple of orders of magnitude below the Planck scale in order for string creation to extract a significant fraction of the energy in coherent motion of the inflaton field. I also comment on a special four-dimensional background which involves only Neveu-Schwarz fields and offers the possibility of studying closed string creation on the worldsheet.
International Nuclear Information System (INIS)
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 world sheet boundary renormalization group 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 existing in the core. We argue that the flux tube acquires a size of order α' through sigma model and string coupling effects, and that confinement effects make the light degrees of freedom heavy and strongly interacting
International Nuclear Information System (INIS)
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
Did BICEP2 see vector modes? First B-mode constraints on cosmic defects.
Moss, Adam; Pogosian, Levon
2014-05-01
Scaling networks of cosmic defects, such as strings and textures, actively generate scalar, vector, and tensor metric perturbations throughout the history of the Universe. In particular, vector modes sourced by defects are an efficient source of the cosmic microwave background B-mode polarization. We use the recently released BICEP2 and POLARBEAR B-mode polarization spectra to constrain properties of a wide range of different types of cosmic strings networks. We find that in order for strings to provide a satisfactory fit on their own, the effective interstring distance needs to be extremely large--spectra that fit the data best are more representative of global strings and textures. When a local string contribution is considered together with the inflationary B-mode spectrum, the fit is improved. We discuss implications of these results for theories that predict cosmic defects. PMID:24836232
Doubled strings, negative strings and null waves
Blair, Chris D A
2016-01-01
We revisit the fundamental string (F1) solution in the doubled formalism. We show that the wave-like solution of double field theory (DFT) corresponding to the F1/pp-wave duality pair is more properly a solution of the DFT action coupled to a doubled sigma model action. The doubled string configuration which sources the pp-wave can be thought of as static gauge with the string oriented in a dual direction. We also discuss the DFT solution corresponding to a vibrating string, carrying both winding and momentum. We further show that the solution dual to the F1 in both time and space can be viewed as a "negative string" solution. Negative branes are closely connected to certain exotic string theories which involve unusual signatures for both spacetime and brane worldvolumes. In order to better understand this from the doubled point of view, we construct a variant of DFT suitable for describing theories in which the fundamental string has a Euclidean worldsheet, for which T-dualities appear to change the spacetim...
International Nuclear Information System (INIS)
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
Chaotic Hybrid Inflation with a Gauged B - L
Carpenter, Linda M
2014-01-01
In this paper we present a novel formulation of chaotic hybrid inflation in supergravity. The model includes a waterfall field which spontaneously breaks a gauged $U_1(B-L)$ at a GUT scale. This allows for the possibility of future model building which includes the standard formulation of baryogenesis via leptogenesis with the waterfall field decaying into right-handed neutrinos. We have not considered the following issues in this short paper, i.e. supersymmetry breaking, dark matter or the gravitino or moduli problems. Our focus is on showing the compatibility of the present model with Planck, WMAP and Bicep2 data.
Open-Closed String Correspondence in Open String Field Theory
Baumgartl, Marco; Sachs, Ivo
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.
Temporal-gauge String Field with Open Strings
Mogami, T.
1994-01-01
A string field theory including open string fields is constructed in the temporal gauge. It consists of string interaction vertices similar to the light-cone gauge string field theory. A slight modification of the definition of the time coordinate is needed because of the existence of the open string end points.
The energy and stability of D-term strings
Collinucci, A; Van Proeyen, A; Collinucci, Andr\\'es; Proeyen, Antoine Van; Smyth, Paul
2007-01-01
Cosmic strings derived from string theory, supergravity or any theory of choice should be stable if we hope to observe them. In this paper we consider D-term strings in D=4, N=1 supergravity with a constant Fayet-Iliopoulos term. We show that the positive deficit angle supersymmetric D-term string is non-perturbatively stable by using standard Witten-Nester techniques to prove a positive energy theorem. Particular attention is paid to the negative deficit angle D-term string, which is known to violate the dominant energy condition. Within the class of string solutions we consider, this violation implies that the negative deficit angle D-term string must have a naked pathology and therefore the positive energy theorem we prove does not apply to it. As an interesting aside, we show that the Witten-Nester charge calculates the total gravitational energy of the D-term string without the need for a cut-off, which may not have been expected.
The energy and stability of D-term strings
International Nuclear Information System (INIS)
Cosmic strings derived from string theory, supergravity or any theory of choice should be stable if we hope to observe them. In this paper we consider D-term strings in D = 4 , N = 1 supergravity with a constant Fayet-Iliopoulos term. We show that the positive deficit angle supersymmetric D-term string is non-perturbatively stable by using standard Witten-Nester techniques to prove a positive energy theorem. Particular attention is paid to the negative deficit angle D-term string, which is known to violate the dominant energy condition. Within the class of string solutions we consider, this violation implies that the negative deficit angle D-term string must have a naked pathology and therefore the positive energy theorem we prove does not apply to it. As an interesting aside, we show that the Witten-Nester charge calculates the total gravitational energy of the D-term string without the need for a cut-off, which may not have been expected
Radial excitations of superconducting strings and their observational consequences
Hartmann, Betti; Peter, Patrick
2016-01-01
We report on the existence of a new type of cosmic string solutions in the Witten model with $U(1)_{\\rm global} \\times \\ U(1)_{\\rm local}$ symmetry. These solutions are superconducting with radially excited condensates. We show that some of these new solutions satisfy Carter's classical stability criterion and discuss some of their possible consequences.
Wiggly Strings in Linearized Brans-Dicke Gravity
Arazi, Andres; Simeone, Claudio
2000-01-01
The metric around a wiggly cosmic string is calculated in the linear approximation of Brans-Dicke theory of gravitation. The equations of motion for relativistic and non-relativistic particles in this metric are obtained. Light propagation is also studied and it is shown that photon trajectories can be bounded.
Scaling configurations of cosmic superstring networks and their cosmological implications
International Nuclear Information System (INIS)
We study the cosmic microwave background temperature and polarization spectra sourced by multitension cosmic-superstring networks. First, we obtain solutions for the characteristic length scales and velocities associated with the evolution of a network of F-D strings, allowing for the formation of junctions between strings of different tensions. We find two distinct regimes describing the resulting scaling distributions for the relative densities of the different types of strings, depending on the magnitude of the fundamental string coupling gs. In one of them, corresponding to the value of the coupling being of order unity, the network's stress-energy power spectrum is dominated by populous light F and D strings, while the other regime, at smaller values of gs, has the spectrum dominated by rare heavy D strings. These regimes are seen in the cosmic microwave background (CMB) anisotropies associated with the network. We focus on the dependence of the shape of the B-mode polarization spectrum on gs and show that measuring the peak position of the B-mode spectrum can point to a particular value of the string coupling. Finally, we assess how this result, along with pulsar bounds on the production of gravitational waves from strings, can be used to constrain a combination of gs and the fundamental string tension μF. Since CMB and pulsar bounds constrain different combinations of the string tensions and densities, they result in distinct shapes of bounding contours in the (μF,gs) parameter plane, thus providing complementary constraints on the properties of cosmic superstrings.
Mass spectrum and Higgs profile in B -L symmetric SSM
Ün, Cem Salih; Özdal, Özer
2016-03-01
We investigate the predictions on the mass spectrum and Higgs boson decays in the supersymmetric standard model extended by U (1 )B-L symmetry (BLSSM). The model requires two singlet Higgs fields, which are responsible for the radiative breaking of U (1 )B-L symmetry. It predicts degenerate right-handed neutrino masses (1.7-2.2 TeV) as well as the right-handed sneutrinos of mass ≲4 TeV . The presence of right-handed neutrinos and sneutrinos triggers the baryon and lepton number violation processes, until they decouple from the standard model particles. Besides, the model predicts rather heavy colored particles; mt ˜ , mb ˜≳1.5 TeV , while mτ ˜≳100 GeV and mχ˜1±≳600 GeV . Even though the implications are similar to the minimal supersymmetric standard model, BLSSM can predict another Higgs boson lighter than 150 GeV. We find that the second Higgs boson can be degenerate with the lightest charge parity (C P )-even Higgs boson of mass about 125 GeV and contribute to the Higgs decay into two photons. In addition, it can provide an explanation for the excess in h →4 l at the mass scale ˜145 GeV .
Self-similar motion of a Nambu-Goto string
Igata, Takahisa; Harada, Tomohiro
2016-01-01
We study the self-similar motion of a string in a self-similar spacetime by introducing the concept of a self-similar string, which is defined as the world sheet to which a homothetic vector field is tangent. It is shown that in the Nambu-Goto theory, the equations of motion for a self-similar string reduce to those for a particle. Moreover, under certain conditions such as the hypersurface orthogonality of the homothetic vector field, the equations of motion for a self-similar string simplify to the geodesic equations on a (pseudo) Riemannian space. As a concrete example, we investigate a self-similar Nambu-Goto string in a spatially flat Friedmann-Lema\\^itre-Robertson-Walker expanding universe with self-similarity, and obtain solutions of open and closed strings, which have various nontrivial configurations depending on the rate of the cosmic expansion. For instance, we obtain a circular solution that evolves linearly in the cosmic time while keeping its configuration by the balance between the effects of t...
String equation from field equation
Gurovich, V T
1996-01-01
It is shown that the string equation can be obtain from field equations. Such work is performed to scalar field. The equation obtained in nonrelativistic limit describes the nonlinear string. Such string has the effective elasticity connencted with the local string curvature. Some examples of the movement such nonlinear elastic string are considered.
Open String Fields As Matrices
Kawano, Teruhiko; Okuyama, Kazumi
2001-01-01
We present a new representation of the string vertices of the cubic open string field theory. By using this three-string vertex, we attempt to identify open string fields as huge-sized matrices by following Witten's idea. By using these huge matrices, we obtain some results about the construction of partial isometries in the algebra of open string fields.
International Nuclear Information System (INIS)
We discuss an aspect of string theory which has been tackled from many different perspectives, but incompletely: the role of nonlocality in the theory and its relation to the geometric shape of the string. In particular, we will describe in quantitative terms how one can zoom out from an extended object such as a string in such a way that, at sufficiently large scales, it appears structureless. Since there are no free parameters in free-string theory, the notion of large scales will be unambiguously determined. In other words, we will be able to answer the question: how and at which scale can the string be seen as a particle? In doing so, we will employ the concept of spectral dimension in a new way with respect to its usual applications in quantum gravity. The operational notions of worldsheet and target spacetime dimension in string theory are also clarified and found to be in mutual agreement. (paper)
He, Guang-Ping
2005-01-01
Though it was proven that secure quantum sealing of a single classical bit is impossible in principle, here we propose an unconditionally secure quantum sealing protocol which seals a classical bit string. Any reader can obtain each bit of the sealed string with an arbitrarily small error rate, while reading the string is detectable. The protocol is simple and easy to be implemented. The possibility of using this protocol to seal a single bit in practical is also discussed.
Zimmerman Jones, Andrew
2010-01-01
Making Everything Easier!. String Theory for Dummies. Learn:. The basic concepts of this controversial theory;. How string theory builds on physics concepts;. The different viewpoints in the field;. String theory's physical implications. Andrew Zimmerman Jones. Physics Guide, About.com. with Daniel Robbins, PhD in Physics. Your plain-English guide to this complex scientific theory. String theory is one of the most complicated sciences being explored today. Not to worry though! This informative guide clearly explains the basics of this hot topic, discusses the theory's hypotheses and prediction
Cohn, J. D.; Periwal, Vipul
1992-01-01
This TASI lecture covers the material in hep-th/9205026. It reviewed the theory of effective strings, with particular emphasis on the manner in which Lorentz invariance is represented. The quantum properties of an example of an effective string are derived from the underlying field theory. A comparison is made with what one would expect if one assumed that quantum effective strings were governed by fundamental string actions such as the Nambu-Goto or the Polyakov actions. It is shown that the...
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)
Radionic nonuniform black strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2004-01-01
Nonuniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a nontrivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes a dilatonic black hole in the single brane limit and reduces to the Reissner-Nordström black hole in the close limit of two-branes. The stability of solutions is demonstrated using catastrophe theory. From the bulk point of view, the black strings are proved to be nonuniform. Nevertheless, the zeroth law of black hole thermodynamics still holds.
Introduction to string field theory
International Nuclear Information System (INIS)
An action is proposed for an interacting closed bosonic string. Our formalism relies heavily on ideas discussed by Witten for the open bosonic string. The gauge fixed quantum action for the fully interacting open bosonic string is obtained
Kolmogorov Complexity, String Information, Panspermia and the Fermi Paradox
Gurzadyan, V G
2005-01-01
Bit strings rather than byte files can be a mode of transmission both for intelligent signals and for travels of extraterrestrial life. Kolmogorov complexity, i.e. the minimal length of a binary coded string completely defining a system, can then, due to its universality, become a key concept in the strategy of the search of extraterrestrials. Evaluating, for illustration, the Kolmogorov complexity of the human genome, one comes to an unexpected conclusion that a low complexity compressed string - analog of Noah's ark - will enable the recovery of the totality of terrestrial life. The recognition of bit strings of various complexity up to incompressible Martin-L\\"{o}f random sequences, will require a different strategy for the analysis of the cosmic signals. The Fermi paradox "Where is Everybody?" can be viewed under in the light of such information panspermia, i.e. a Universe full of traveling life streams.
Academic training : String Theory for Pedestrians
2007-01-01
LECTURE SERIES 29, 30, 31 January 2007 from 11.00 to 12.00 hrs Main Auditorium, bldg. 500 on 29 and 30 January TH Auditorium, Bldg 4, 3-006, on 31 January String Theory for Pedestrians B. ZWIEBACH/MIT, Cambridge, USA In this 3-lecture series I will discuss the basics of string theory, some physical applications, and the outlook for the future. Â I will begin with the main concepts of the classical theory and theÂ application to the study of cosmic superstrings.Â Then I will turnÂ to the quantum theory and discussÂ applications toÂ the investigation ofÂ hadronic spectra and theÂ recentlyÂ discovered quark-gluon plasma.Â Â I will concludeÂ with a sketch of string models of particle physicsÂ and showing some avenues that may lead to aÂ completeÂ formulation ofÂ string theory. Â
Kunitomo, Hiroshi; Sakaguchi, Makoto; Tokura, Akira
1994-01-01
It has been shown that there is a sequential embedding structure in a $w_N$\\ string theory based on a linearized $W_N$\\ algebra. The $w_N$\\ string theory is obtained as a special realization of the $w_{N+1}$\\ string. The $w_{\\infty}$\\ string theory is a universal string theory in this sense. We have also shown that there is a similar sequence for $N=1$\\ string theory. The $N=1\\ w_N$\\ string can be given as a special case of the $N=1\\ w_{N+1}$\\ string. In addition, we show that the $w_3$\\ stri...
Semilocal and electroweak strings
Achucarro, A; Vachaspati, T
2000-01-01
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 exter
Peeters, K.; Plefka, J; Zamaklar, m.
2005-01-01
We review a study of the semiclassical decay of macroscopic spinning strings in AdS5 x S5 as well as its dual gauge theory description. The conservation of the infinite tower of commuting charges in the semiclassical string sigma-model description of the process suggests that the decay channel of maximal probability should preserve integrability in the gauge theory.
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 – speedup...
Towards open-closed string duality: Closed Strings as Open String Fields
Bonora, L.; Bouatta, N.; Maccaferri, C.
2006-01-01
We establish a translation dictionary between open and closed strings, starting from open string field theory. Under this correspondence, (off-shell) level-matched closed string states are represented by star algebra projectors in open string field theory. Particular attention is paid to the zero mode sector, which is indispensable in order to generate closed string states with momentum. As an outcome of our identification, we show that boundary states, which in closed string theory represent...
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...
String Field Theory of $c\\leq 1$ Noncritical Strings
Ishibashi, N.; Kawai, H
1993-01-01
We construct a string field Hamiltonian for a noncritical string theory with the continuum limit of the Ising model or its generalization as the matter theory on the worldsheet. It consists of only three string vertices as in the case for $c=0$. We also discuss a general consistency condition that should be satisfied by this kind of string field Hamiltonian.
Closed String Amplitudes in Open String Field Theory
Takahashi, Tomohiko; Zeze, Syoji
2003-01-01
We investigate gauge invariant operators corresponding to on-shell closed string states in open string field theory. Using both oscillator representation and conformal mapping techniques, we calculate a two closed string tachyon amplitude that connects two gauge invariant operators by an open string propagator.We find that this amplitude is in a complete agreement with the usual disc amplitude.
Half-String Approach to Closed String Field Theory
Antón, Fernando; Abdurrahman, A.; Bordes Villagrasa, José M.
1993-01-01
In this letter we present an operator formalism for Closed String Field Theory based on closed half-strings. Our results indicate that the restricted polyhedra of the classical non-polynomial string field theory, can be represented as traces of infinite matrices, with operator insertions that reparametrise the half-strings.
Closed string cohomology in open string field theory
Moeller, Nicolas; Sachs, Ivo
2011-07-01
We show that closed string states in bosonic string field theory are encoded in the cyclic cohomology of cubic open string field theory (OSFT) which, in turn, classifies the deformations of OSFT. This cohomology is then shown to be independent of the open string background. Exact elements correspond to closed string gauge transformations, generic boundary deformations of Witten's 3-vertex and infinitesimal shifts of the open string background. Finally it is argued that the closed string cohomology and the cyclic cohomology of OSFT are isomorphic to each other.
Cosmic impacts, cosmic catastrophes. I
Chapman, Clark R.; Morrison, David
1989-01-01
The discovery of cosmic impacts and their effects on the earth's surface are discussed. The manner in which the object impacts with the earth is described. The formation of crytovolcanic structures by craters is examined. Examples of cosmic debris collisions with earth, in particular the Tunguska explosion of 1908 and the Meteor Crater in Arizona, are provided.
Mass spectrum of the minimal SUSY B-L model
O'Leary, Ben; Staub, Florian
2011-01-01
The origin of R-parity in supersymmetric models can be explained if \\BL is part of the gauge group. We discuss the mass spectrum of the minimal $U(1)_Y \\times U(1)_{B-L}$ model based on a GUT implementation using CMSSM-like boundary conditions. Here we focus in particular on the Higgs and neutralino sectors in this class of models. While the neutralinos can have masses as low as 100 GeV, we show that the requirement of being consistent with existing bounds on the $Z'$ implies that in general the sfermions have masses in the multi-TeV range. In the extended Higgs sector we show the existence of a second light state which, however, will be difficult to observe, while having at the same time a SM-like Higgs in a mass range close to 120 GeV. Moreover, we propose a set of benchmark scenarios for phenomenological studies. On the technical side we demonstrate that gauge kinetic mixing effects can be quite important, affecting in particular the Higgs and the neutralino sectors. Not only can they shift the mass of the...
Complex Scalar DM in a B-L Model
Sánchez-Vega, B L; Schmitz, E R
2014-01-01
In this work, we implement a complex scalar Dark Matter (DM) candidate in a $U(1)_{B-L}$ gauge extension of the Standard Model. The model contains three right handed neutrinos with different quantum numbers and a rich scalar sector, with extra doublets and singlets. In principle, these extra scalars can have VEVs ($V_{\\Phi}$ and $V_{\\phi}$ for the extra doublets and singlets, respectively) belonging to different energy scales. In the context of $\\zeta\\equiv\\frac{V_{\\Phi}}{V_{\\phi}}\\ll1$, which allows to obtain naturally light active neutrino masses and mixing compatible with neutrino experiments, the DM candidate arises by imposing a $Z_{2}$ symmetry on a given complex singlet, $\\phi_{2}$, in order to make it stable. After doing a study of the scalar potential and the gauge sector, we obtain all the DM dominant processes concerning the relic abundance and direct detection. Then, for a representative set of parameters, we found that a complex DM with mass around $200$ GeV, for example, is compatible with the c...
Bu, Tian-Ming; Zhang, Peng
2011-01-01
Many problems in Computer Science can be abstracted to the following question: given a set of objects and rules respectively, which new objects can be produced? In the paper, we consider a succinct version of the question: given a set of binary strings and several operations like conjunction and disjunction, which new binary strings can be generated? Although it is a fundamental problem, to the best of our knowledge, the problem hasn't been studied yet. In this paper, an O(m^2n) algorithm is presented to determine whether a string s is representable by a set W, where n is the number of strings in W and each string has the same length m. However, looking for the minimum subset from a set to represent a given string is shown to be NP-hard. In addition, we prove that counting the number of strings representable is #P-complete. But if the operator negation can be used, the number is some power of 2. This di?erence maybe help us understand the problem more profoundly.
Supersymmetry and String Theory
Dine, Michael
2016-01-01
Preface to the first edition; Preface to the second edition; A note on choice of metric; Text website; Part I. Effective Field Theory: The Standard Model, Supersymmetry, Unification: 1. Before the Standard Model; 2. The Standard Model; 3. Phenomenology of the Standard Model; 4. The Standard Model as an effective field theory; 5. Anomalies, instantons and the strong CP problem; 6. Grand unification; 7. Magnetic monopoles and solitons; 8. Technicolor: a first attempt to explain hierarchies; Part II. Supersymmetry: 9. Supersymmetry; 10. A first look at supersymmetry breaking; 11. The Minimal Supersymmetric Standard Model; 12. Supersymmetric grand unification; 13. Supersymmetric dynamics; 14. Dynamical supersymmetry breaking; 15. Theories with more than four conserved supercharges; 16. More supersymmetric dynamics; 17. An introduction to general relativity; 18. Cosmology; 19. Astroparticle physics and inflation; Part III. String Theory: 20. Introduction; 21. The bosonic string; 22. The superstring; 23. The heterotic string; 24. Effective actions in ten dimensions; 25. Compactification of string theory I. Tori and orbifolds; 26. Compactification of string theory II. Calabi–Yau compactifications; 27. Dynamics of string theory at weak coupling; 28. Beyond weak coupling: non-perturbative string theory; 29. Large and warped extra dimensions; 30. The landscape: a challenge to the naturalness principle; 31. Coda: where are we headed?; Part IV. The Appendices: Appendix A. Two-component spinors; Appendix B. Goldstone's theorem and the pi mesons; Appendix C. Some practice with the path integral in field theory; Appendix D. The beta function in supersymmetric Yang–Mills theory; References; Index.
Universality and string theory
Bachlechner, Thomas Christian
The first run at the Large Hadron Collider has deeply challenged conventional notions of naturalness, and CMB polarization experiments are about to open a new window to early universe cosmology. As a compelling candidate for the ultraviolet completion of the standard model, string theory provides a prime opportunity to study both early universe cosmology and particle physics. However, relating low energy observations to ultraviolet physics requires knowledge of the metastable states of string theory through the study of vacua. While it is difficult to directly obtain infrared data from explicit string theory constructions, string theory imposes constraints on low energy physics. The study of ensembles of low energy theories consistent with ultra-violet constraints provides insight on generic features we might expect to occur in string compactifications. In this thesis we present a statistical treatment of vacuum stability and vacuum properties in the context of random supergravity theories motivated by string theory. Early universe cosmology provides another avenue to high energy physics. From the low energy perspective large field inflation is typically considered highly unnatural: the scale relevant for the diameter of flat regions in moduli space is sub-Planckian in regions of perturbative control. To approach this problem, we consider generic Calabi-Yau compactifications of string theory and find that super-Planckian diameters of axion fundamental domains in fact arise generically. We further demonstrate that such super-Planckian flat regions are plausibly consistent with theWeak Gravity Conjecture.
Veneziano Amplitude for Winding Strings
Khuri, Ramzi R.
1993-01-01
String configurations with nonzero winding number describe soliton string states. We compute the Veneziano amplitude for the scattering of arbitrary winding states and show that in the large radius limit the strings always scatter trivially and with no change in the individual winding numbers of the strings. In this limit, then, these states scatter as true solitons.
Recent Results in String Duality
Polchinski, Joseph
1995-01-01
This is a talk given at YKIS '95, primarily to non-string theorists. I review the evidence for string duality, the principle that any string theory at strong coupling looks like another string theory at weak coupling. A postscript summarizes developments since the conference.
A classical instability for black strings and p-branes
Energy Technology Data Exchange (ETDEWEB)
Gregory, R. [Chicago Univ., IL (United States). Enrico Fermi Inst.; Laflamme, R. [Los Alamos National Lab., NM (United States)
1993-06-01
We investigate the evolution of small perturbations around black of strings and branes which are low energy solutions of string theory. For simplicity we focus attention on the zero charge case and show that there are unstable modes for a range of time frequency and wavelength in the extra 10 - D dimensions. These perturbations can be stabilized if the extra dimensions are compactified to a scale smaller than the minimum wavelength for which instability occurs and thus will not affect large astrophysical black holes in four dimensions. We comment on the implications of this result for the Cosmic Censorship Hypothesis
A classical instability for black strings and p-branes
Energy Technology Data Exchange (ETDEWEB)
Gregory, R. (Chicago Univ., IL (United States). Enrico Fermi Inst.); Laflamme, R. (Los Alamos National Lab., NM (United States))
1993-01-01
We investigate the evolution of small perturbations around black of strings and branes which are low energy solutions of string theory. For simplicity we focus attention on the zero charge case and show that there are unstable modes for a range of time frequency and wavelength in the extra 10 - D dimensions. These perturbations can be stabilized if the extra dimensions are compactified to a scale smaller than the minimum wavelength for which instability occurs and thus will not affect large astrophysical black holes in four dimensions. We comment on the implications of this result for the Cosmic Censorship Hypothesis
The issue of Dark Energy in String Theory
Mavromatos, Nikolaos E
2006-01-01
Recent astrophysical observations, pertaining to either high-redshift supernovae or cosmic microwave background temperature fluctuations, as those measured recently by the WMAP satellite, provide us with data of unprecedented accuracy, pointing towards two (related) facts: (i) our Universe is accelerated at present, and (ii) more than 70 % of its energy content consists of an unknown substance, termed dark energy, which is believed responsible for its current acceleration. Both of these facts are a challenge to String theory. In this review I outline briefly the challenges, the problems and possible avenues for research towards a resolution of the Dark Energy issue in string theory.
D3/D7 Brane Inflation and Semilocal Strings
Dasgupta, Keshav; Hsu, Jonathan P.; Kallosh, Renata(Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA, 94305-4060, U.S.A.); Linde, Andrei; Zagermann, Marco
2004-01-01
Among the inflationary models based on string theory, the D3/D7 model has the advantage that the flatness of the inflaton potential can be protected even with moduli stabilization. However, the Abrikosov-Nielsen-Olesen BPS cosmic strings produced at the end of original D3/D7 inflation lead to an additional contribution to the CMB anisotropy. To make this contribution consistent with the WMAP results one needs an extremely small gauge coupling in the effective D-term inflation model. Such coup...
DEFF Research Database (Denmark)
Schäfer, Mirko; Greiner, Martin
Chaotic strings are coupled Tchebyscheff maps on a ring-network. With a well-specified empirical prescription they are able to explain the coupling constants of the standard model of elementary particle physics. This empirical relationship is tested further by introducing a tunable disorder 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 of the...
Duality, strings and inflation
International Nuclear Information System (INIS)
Arguments based on thermodynamics and on the analysis of string creation effects in expanding spaces suggest the existence of an inflationary phase in the early universe for theories of closed strings. Einstein's equations on the other hand do not support such expectations. The author solves this apparent paradox by noticing that Einstein's equations must be modified at the scale at which this inflationary phase takes place, so that the new equations satisfy the closed string duality principle. Inflation is natural in the context of such modifications and he gives an estimate of the amount of inflation in this early epoch
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.
Förste, S; Forste, Stefan; Louis, Jan
1996-01-01
In this lecture we review some of the recent developments in string theory on an introductory and qualitative level. In particular we focus on S-T-U dualities of toroidally compactified ten-dimensional string theories and outline the connection to M-theory. Dualities among string vacua with less supersymmetries in six and four space-time dimensions is discussed and the concept of F-theory is briefly presented. (Lecture given by J. Louis at the Workshop on Gauge Theories, Applied Supersymmetry and Quantum Gravity, Imperial College, London, UK, July 5--10, 1996.)
Gukov, S.; Klebanov, I. R.; Polyakov, A. M.
1997-01-01
An $(n, 1)$ string is a bound state of a D-string and $n$ fundamental strings. It may be described by a D-string with a world volume electric field turned on. As the electric field approaches its critical value, $n$ becomes large. We calculate the 4-point function for transverse oscillations of an $(n, 1)$ string, and the two-point function for massless closed strings scattering off an $(n, 1)$ string. In both cases we find a set of poles that becomes dense in the large $n$ limit. The effecti...
Reheating for closed string inflation
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22603 Hamburg (Germany); Mazumdar, Anupam, E-mail: michele.cicoli@desy.de, E-mail: a.mazumdar@lancaster.ac.uk [Physics Department, Lancaster University, Lancaster, LA1 4YB (United Kingdom)
2010-09-01
We point out some of the outstanding challenges for embedding inflationary cosmology within string theory studying the process of reheating for models where the inflaton is a closed string mode parameterising the size of an internal cycle of the compactification manifold. A realistic model of inflation must explain the tiny perturbations in the cosmic microwave background radiation and also how to excite the ordinary matter degrees of freedom after inflation, required for the success of Big Bang Nucleosynthesis. We study these issues focusing on two promising inflationary models embedded in LARGE volume type IIB flux compactifications. We show that phenomenological requirements and consistency of the effective field theory treatment imply the presence at low energies of a hidden sector together with a visible sector, where the Minimal Supersymmetric Standard Model fields are residing. A detailed calculation of the inflaton coupling to the fields of the hidden sector, visible sector, and moduli sector, reveals that the inflaton fails to excite primarily the visible sector fields, instead hidden sector fields are excited copiously after the end of inflation. This sets severe constraints on hidden sector model building where the most promising scenario emerges as a pure N = 1 SYM theory, forbidding the kinematical decay of the inflaton to the hidden sector. In this case it is possible to reheat the Universe with the visible degrees of freedom even though in some cases we discover a new tension between TeV scale SUSY and reheating on top of the well-known tension between TeV scale SUSY and inflation.
Reheating for closed string inflation
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mazumdar, Anupam [Lancaster Univ. (United Kingdom). Physics Dept.; Copenhagen Univ. (Denmark). Niels Bohr Institute
2010-05-15
We point out some of the outstanding challenges for embedding inflationary cosmology within string theory studying the process of reheating for models where the inflaton is a closed string mode parameterising the size of an internal cycle of the compactification manifold. A realistic model of inflation must explain the tiny perturbations in the cosmic microwave background radiation and also how to excite the ordinary matter degrees of freedom after inflation, required for the success of Big Bang Nucleosynthesis. We study these issues focusing on two promising inflationary models embedded in LARGE volume type IIB flux compactifications. We show that phenomenological requirements and consistency of the effective field theory treatment imply the presence at low energies of a hidden sector together with a visible sector, where the Minimal Supersymmetric Standard Model fields are residing. A detailed calculation of the inflaton coupling to the fields of the hidden sector, visible sector, and moduli sector, reveals that the inflaton fails to excite primarily the visible sector fields, instead hidden sector fields are excited copiously after the end of inflation. This sets severe constraints on hidden sector model building where the most promising scenario emerges as a pure N=1 SYM theory, forbidding the kinematical decay of the inflaton to the hidden sector. In this case it is possible to reheat the Universe with the visible degrees of freedom even though in some cases we discover a new tension between TeV scale SUSY and reheating on top of the well-known tension between TeV scale SUSY and inflation. (orig.)
Cubic Twistorial String Field Theory
Berkovits, Nathan; Motl, Lubos
2004-01-01
Witten has recently proposed a string theory in twistor space whose D-instanton contributions are conjectured to compute N=4 super-Yang-Mills scattering amplitudes. An alternative string theory in twistor space was then proposed whose open string tree amplitudes reproduce the D-instanton computations of maximal degree in Witten's model. In this paper, a cubic open string field theory action is constructed for this alternative string in twistor space, and is shown to be invariant under parity ...
Friction Domination with Superconducting Strings
Dimopoulos, Konstantinos; Davis, Anne-Christine
1997-01-01
We investigate the evolution of a superconducting string network with arbitrary, constant string current in the friction dominated regime. In the absence of an external magnetic field the network always reaches a scaling solution. However, for string current stronger than a critical value, it is different than the usual, horizon-scaling of the non-superconducting string case. In this case the friction domination era never ends. Whilst the superconducting string network can be much denser than...
Amadini, Roberto; Flener, Pierre; Pearson, Justin; Scott, Joseph D.; Stuckey, Peter J.; Tack, Guido
2016-01-01
Strings are extensively used in modern programming languages and constraints over strings of unknown length occur in a wide range of real-world applications such as software analysis and verification, testing, model checking, and web security. Nevertheless, practically no CP solver natively supports string constraints. We introduce string variables and a suitable set of string constraints as builtin features of the MiniZinc modelling language. Furthermore, we define an interpreter for convert...
Scattering from Electroweak Strings
Lo, Hoi-Kwong
1994-01-01
The scattering of a charged fermion from an electroweak string is studied. Owing to an amplification of the wave function at the core radius, the cross sections for helicity flip processes can be largely enhanced. For $0
International Nuclear Information System (INIS)
Superstrings being consistent theories that include gravity have to produce classical gravity within limits provided by unambiguous quantum effects. Through the study of a hard scattering process - clearly provided by string theory - it is shown that infinite genus calculations give indeed rise to a classical limit, when 'large' distances are explored, as well as quantum effects. These are dominant at distances of the order of the string length (related to the Planck length) but may extend much beyond that region hinting indeed to gravitational instabilities. Below the string length even space-time loses meaning as a classical concept. A new position-momentum uncertainty relation is produced that assigns to the string length the meaning of a minimum observable distance. (orig.)
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.
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.
Universality in string interactions
Huang, Yu-tin; Wen, Congkao
2016-01-01
In this letter, we provide evidence for universality in the low-energy expansion of tree-level string interactions. More precisely, in the alpha'-expansion of tree-level scattering amplitudes, we conjecture that the leading transcendental coefficient at each order in alpha' is universal for all perturbative string theories. We have checked this universality up to seven points and trace its origin to the ability to restructure the disk integrals of open bosonic string into those of the superstring. The accompanying kinematic functions have the same low-energy limit and do not introduce any transcendental numbers in their alpha'-corrections. Universality in the closed-string sector then follows from the KLT-relations.
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.
Sphalerons and Electroweak Strings
Soni, Vikram
1995-01-01
We show that the sphaleron energy which identifies with the (instanton) potential barrier for B-violation is reduced in the presence (background) of an electroweak Z-string. We also show that for large enough Higgs coupling, $\\lambda$, the sphaleron energy can go negative. For such $\\lambda$, electroweak Z-strings can reduce their energy by accumulating sphaleron bound states. This further endows them with baryon number. Given our approximation, the value of $\\lambda$ at which this occurs is ...
Universality in Effective Strings
Jaimungal, S.; Semenoff, G. W.; Zarembo, K.
1998-01-01
We demonstrate that, due to the finite thickness of domain walls, and the consequent ambiguity in defining their locations, the effective string description obtained by integrating out bulk degrees of freedom contains ambiguities in the coefficients of the various geometric terms. The only term with unambiguous coefficient is the zeroth order Nambu-Goto term. We argue that fermionic ghost fields which implement gauge-fixing act to balance these ambiguities. The renormalized string tension, ob...
International Nuclear Information System (INIS)
Some issues related to the vacuum geometry of strings are raised and discussed. In particular, we stress the role of conformal and Weyl invariance as a consistency requirement for formulating string dynamics in curved space. The case of the compact group is discussed in some detail. The current algebra representation which is obtained is equivalent to the Frenkel-Kac construction for the k=1 level of the Kac-Moody algebra. (author)
Manipulating Strings in Python
William J. Turkel; Adam Crymble
2012-01-01
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.
Frampton, Paul H.
2016-04-01
In this note, I recollect a two-week period in September 1968 when I factorized the Veneziano model using string variables in Chicago. Professor Yoichiro Nambu went on to calculate the N-particle dual resonance model and then to factorize it on an exponential degeneracy of states. That was in 1968 and the following year 1969 he discovered the string action. I also include some other reminiscences of Nambu who passed away on July 5, 2015.
International Nuclear Information System (INIS)
These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R4-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude
Constraints on string cosmology
International Nuclear Information System (INIS)
String theory contains sources like orientifold planes that support higher derivative interactions. These interactions make static flux compactifications possible which are forbidden in supergravity. They can also lead to violations of the strong energy condition which is needed for an accelerating universe. We examine how large a violation is possible in the context of the heterotic string compactified to four dimensions. We find that de Sitter solutions are still not possible but that classically forbidden anti-de Sitter solutions are possible. (paper)
Energy Technology Data Exchange (ETDEWEB)
Ahlén, Olof, E-mail: olof.ahlen@aei.mpg.de [Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), Am Mühlenberg 1, DE-14476 Potsdam (Germany)
2015-12-17
These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R{sup 4}-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude.
Directory of Open Access Journals (Sweden)
Meng Sun
2015-08-01
Full Text Available We give a general illumination of a rotating black string falling into a rotating horizon in dimension D=5. It is a configuration of one smooth intersection between these two objects when the spacetime is axisymmetric and in the limit that the thickness of the black hole is much larger than the thickness of the black string. Following this configuration, we further extend them to the rotating and charged flows.
Dual strings and magnetohydrodynamics
Olesen, P.
1995-01-01
We investigate whether dual strings could be solutions of the magnetohydrodynamics equations in the limit of infinite conductivity. We find that the induction equation is satisfied, and we discuss the Navier-Stokes equation (without viscosity) with the Lorentz force included. We argue that the dual string equations (with a non-universal maximum velocity) should describe the large scale motion of narrow magnetic flux tubes, because of a large reparametrization (gauge) invariance of the magneti...
Itoyama, H
2016-01-01
This is a brief summary of an introductory lecture for students and scholars in general given by the author at Nambu Memorial Symposium which was held at Osaka City University on September 29, 2015. We review the invention of string theory by Professor Yoichiro Nambu following the discovery of the Veneziano amplitude. We also discuss Professor Nambu's proposal on string theory in the Schild gauge in 1976 which is related to the matrix model of Yang-Mills type.
International Nuclear Information System (INIS)
This paper reports on String Theory which is recognized as a remarkable case of Conformally Invariant Two-Dimensional Field Theory. It is built, with some restrictions, out of representations of the Virasoro algebra (or, rather, for closed strings, of two commuting copies of it). The first such restriction comes from the requirement of exact conformal invariance, or vanishing conformal anomaly. This is a condition on the field content of the relevant two- dimensional models. For a long time it was associated to the critical dimension of space time, 26 for the bosonic string and 10 for the superstrings. Nowadays, these numbers are seen as a much looser requirement. The total central charge of each representation of the Virasoro algebra must simply equal 26 in the bosonic case, and 15 in the fermionic case, two numbers well connected to Faddeev-Popov ghosts and their contributions to the conformal anomaly. Orbifolds were introduced in String Theory as simple examples of string compactification, albeit ones with internal dimensions living in spaces with singular points. These spaces are obtained from smooth coverings by suitable identifications. There is a vast literature on all this, at least for the case of closed strings, and is often quite technical. The usual cases deal with tori where identification corresponding to discrete Abelian groups are made
Power suppression at large scales in string inflation
International Nuclear Information System (INIS)
We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters
Power suppression at large scales in string inflation
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Dipartimento di Fisica ed Astronomia, Università di Bologna, via Irnerio 46, Bologna, 40126 (Italy); Downes, Sean; Dutta, Bhaskar, E-mail: mcicoli@ictp.it, E-mail: sddownes@physics.tamu.edu, E-mail: dutta@physics.tamu.edu [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX, 77843-4242 (United States)
2013-12-01
We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.
Power Suppression at Large Scales in String Inflation
Cicoli, Michele; Dutta, Bhaskar
2013-01-01
We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-6...
Dilaton and off-shell (non-critical string) effects in Boltzmann equation for species abundances
Lahanas, A B; Nanopoulos, Dimitri V
2006-01-01
In this work we derive the modifications to the Boltzmann equation governing the cosmic evolution of relic abundances induced by dilaton dissipative-source and non-critical-string terms in dilaton-driven non-equilibrium string Cosmologies. We also discuss briefly the most important phenomenological consequences, including modifications of the constraints on the available parameter space of cosmologically appealing particle physics models, imposed by recent precision data of astrophysical measurements.
Dilaton and off-shell (non-critical string) effects in Boltzmann equation for species abundances
Lahanas, Ab; Mavromatos, Ne; Nanopoulos, Dv
In this work we derive the modifications to the Boltzmann equation governing the cosmic evolution of relic abundances induced by dilaton dissipative-source and non-critical-string terms in dilaton-driven non-equilibrium string Cosmologies. We also discuss briefly the most important phenomenological consequences, including modifications of the constraints on the available parameter space of cosmologically appealing particle physics models, imposed by recent precision data of astrophysical measurements.
Constraints on cosmic superstrings from Kaluza-Klein emission.
Dufaux, Jean-François
2012-07-01
Cosmic superstrings interact generically with a tower of light and/or strongly coupled Kaluza-Klein (KK) modes associated with the geometry of the internal space. We study the production of KK particles by cosmic superstring loops, and show that it is constrained by big bang nucleosynthesis. We study the resulting constraints in the parameter space of the underlying string theory model and highlight their complementarity with the regions that can be probed by current and upcoming gravitational wave experiments. PMID:23031097
New Developments in String Gravity and String Cosmology.A Summary Report
Sanchez, Norma G.
2002-01-01
New Developments in String Gravity and String Cosmology are reported: 1-String driven cosmology and its Predictions. 2-The primordial gravitational wave background in string cosmology. 3-Non-singular string cosmologies from Exact Conformal Field Theories. 4-Quantum Field Theory, String Temperature and the String Phase of de Sitter space-time, 5-Hawking Radiation in String Theory and the String Phase of Black Holes. 6-New Dual Relation between Quantum Field Theory regimes and String regimes in...
Exceptional groups from open strings
Gaberdiel, Matthias R.; Zwiebach, Barton
1997-01-01
We consider type IIB theory compactified on a two-sphere in the presence of mutually nonlocal 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 o...
String Theory: Progress and Problems
Schwarz, John H.
2007-01-01
String theory builds on the great legacy of Yukawa and Tomonaga: New degrees of freedom and control of the UV are two important themes. This talk will give an overview of some of the progress and some of the unsolved problems that characterize string theory today. It is divided into two parts: (1) Connecting String Theory to the Real World; (2) Gauge Theory/String Theory Duality. Two other major subjects, which I will omit, are Black Holes in String Theory and The Impact of String Theory on M...
On the evolution of abelian-Higgs string networks
Moore, J N
1998-01-01
We study the evolution of abelian-Higgs string networks in numerical simulations. These are compared against a modified velocity-dependent one scale model for cosmic string network evolution. This incorporates the contributions of loop production, massive radiation and friction to the energy loss processes that are required for scaling evolution. We find that the loop distribution statistics in the simulations are consistent with the long-time scaling of the network being dominated by loop production. For an oscillating sinusoidal perturbation, we also demonstrate that the power emitted into massive radiation decays strongly with wavelength. Putting these observations together and extrapolating, we believe there is insufficient evidence to reject the the standard picture of string network evolution in favour of one where direct massive radiation is the dominant decay mechanism, a proposal which has attracted much recent interest.
On the Evolution of Abelian-Higgs String Networks
Moore, J N; Martins, C J
2002-01-01
We study the evolution of Abelian-Higgs string networks in numerical simulations. These are compared against a modified velocity-dependent one scale model for cosmic string network evolution. This incorporates the contributions of loop production, massive radiation and friction to the energy loss processes that are required for scaling evolution. We discuss the relative importance of these mechanisms for the evolution of the network. We find that the loop distribution statistics in the simulations are consistent with the long-time scaling of the network being dominated by loop production. For an oscillating sinusoidal perturbation, we also demonstrate that the power emitted into massive radiation decays strongly with wavelength. Putting these observations together and extrapolating, we believe there is insufficient evidence to reject the the standard picture of string network evolution in favour of one where direct massive radiation is the dominant decay mechanism, a proposal which has attracted much recent i...
Strings and fundamental physics
International Nuclear Information System (INIS)
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.)
Haghighat, Babak; Kozcaz, Can; Lockhart, Guglielmo; Vafa, Cumrun
2013-01-01
M2 branes suspended between adjacent parallel M5 branes lead to light strings, the `M-strings'. In this paper we compute the elliptic genus of M-strings, twisted by maximally allowed symmetries that preserve 2d (2,0) supersymmetry. In a codimension one subspace of parameters this reduces to the elliptic genus of the (4,4) supersymmetric A_{n-1} quiver theory in 2d. We contrast the elliptic genus of N M-strings with the (4,4) sigma model on the N-fold symmetric product of R^4. For N=1 they are the same, but for N>1 they are close, but not identical. Instead the elliptic genus of (4,4) N M-strings is the same as the elliptic genus of (4,0) sigma models on the N-fold symmetric product of R^4, but where the right-moving fermions couple to a modification of the tangent bundle. This construction arises from a dual A_{n-1} quiver 6d gauge theory with U(1) gauge groups. Moreover we compute the elliptic genus of domain walls which separate different numbers of M2 branes on the two sides of the wall.
Energy Technology Data Exchange (ETDEWEB)
Chernin, Artur D [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
2001-11-30
Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)
International Nuclear Information System (INIS)
Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)
N-string vertices in string field theory
Bordes Villagrasa, José M.; Abdurrahman, A.; Antón, Fernando
1994-01-01
We give the general form of the vertex corresponding to the interaction of an arbitrary number of strings. The technique employed relies on the ``comma" representation of String Field Theory where string fields and interactions are represented as matrices and operations between them such as multiplication and trace. The general formulation presented here shows that the interaction vertex of N strings, for any arbitrary N, is given as a function of particular combinations of matrices correspon...
Probabilistic Threshold Indexing for Uncertain Strings
Thankachan, Sharma V.; Patil, Manish; Shah, Rahul; Biswas, Sudip
2015-01-01
Strings form a fundamental data type in computer systems. String searching has been extensively studied since the inception of computer science. Increasingly many applications have to deal with imprecise strings or strings with fuzzy information in them. String matching becomes a probabilistic event when a string contains uncertainty, i.e. each position of the string can have different probable characters with associated probability of occurrence for each character. Such uncertain strings are...
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
Bianchi type-VIh string cloud cosmological models with bulk viscosity
Tripathy, Sunil K.; Behera, Dipanjali
2010-11-01
String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VIh metric in the frame work of general relativity. The field equations are solved for massive string cloud in presence of bulk viscosity. A general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered. The physical and kinematical properties of the models have been discussed in detail and the limits of the anisotropic parameter responsible for different phases of the universe are explored.