115,902 research outputs found
Lattice-Renormalization of the Polyakov Loop
No full textZantow F. Lattice-Renormalization of the Polyakov Loop. Bielefeld: Fakultät für Physik; 2003
New superstring isometries and hidden dimensions
No full textWe study the hierarchy of hidden space-time symmetries of noncritical strings in RNS formalism, realized nonlinearly. Under these symmetry transformations the variation of the matter part of the RNS action is canceled by that of the ghost part. These symmetries, referred to as the α-symmetries, are induced by special space-time generators, violating the equivalence of ghost pictures. We classify the α-symmetry generators in terms of superconformal ghost cohomologies Hn ∼ H -n-2(n andgt; 0) and associate these generators with a chain of hidden space-time dimensions, with each ghost cohomology Hn ∼ H -n-2 contributing an extra dimension. Namely, we show that each ghost cohomology Hn ∼ H-n-2 of noncritical superstring theory in d-dimensions contains d + n + 1 α-symmetry generators and the generators from Hk ∼ H-k-2, 1 andlt; k andlt; n, combined together, extend the space-time isometry group from the naive SO(d, 2) to SO(d + n, 2). In the simplest case of n = 1 the α-generators are identified with the extra symmetries of the 2T-physics formalism, also known to originate from a hidden space-time dimension. © World Scientific Publishing Company.Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.045019; Bars I, 1999, PHYS REV D, V59, DOI 10.1103-PhysRevD.59.125004; Bars I, 1999, PHYS LETT B, V457, P275, DOI 10.1016-S0370-2693(99)00582-1; Bars I, 1997, PHYS REV D, V55, P2373, DOI 10.1103-PhysRevD.55.2373; KLEBANOV IR, 1991, MOD PHYS LETT A, V6, P3273, DOI 10.1142-S021773239100378X; KLEBANOV IR, 1993, PHYS REV LETT, V71, P3243, DOI 10.1103-PhysRevLett.71.3243; LIAN BH, 1991, PHYS LETT B, V254, P417, DOI 10.1016-0370-2693(91)91177-W; Polyakov D, 2007, INT J MOD PHYS A, V22, P1375, DOI 10.1142-S0217751X07035148; Polyakov D, 2007, INT J MOD PHYS A, V22, P2441, DOI 10.1142-S0217751X07036269; Vafa C, 1996, NUCL PHYS B, V469, P403, DOI 10.1016-0550-3213(96)00172-1; WITTEN E, 1992, NUCL PHYS B, V373, P187, DOI 10.1016-0550-3213(92)90454-J44
GL(1) charged states in twistor string theory
No full textWe discuss the appearance of the GL(1) charged physical operators in the twistor string theory. These operators are shown to be BRST-invariant and non-trivial and some of their correlators and conformal β-functions are computed. Remarkably, the non-conservation of the GL(1) charge in interactions involving these operators, is related to the anomalous term in the Kac-Moody current algebra. While these operators play no role in the maximum helicity violating (MHV) amplitudes, they are shown to contribute non-trivially to the non-MHV correlators in the presence of the worldsheet instantons. We argue that these operators describe the non-perturbative dynamics of solitons in conformal supergravity. The exact form of such solitonic solutions is yet to be determined. © 2005 Published by Elsevier B.V.Azcarraga J., 1989, PHYS REV LETT, V3, P2443; Berkovits N., 2004, JHEP, V0404; Berkovits N., 2004, JHEP, V0408, P009; CACHAZO F, 2004, JHEP, V410; Gubser SS, 1998, PHYS LETT B, V428, P105, DOI 10.1016-S0370-2693(98)00377-3; Maldacena J M, 1998, ADV THEOR MATH PHYS, V2, P231, DOI DOI 10.1023-A:1026654312961; POLYAKOV D, HEPTH0406079; POLYAKOV D, IN PRESS INT J MOD P; Witten E., 1998, ADV THEOR MATH PHYS, V2, P253, DOI DOI 10.1016-S0370-1573(99)00083-6; Witten E., HEPTH9112056; Witten E, 2004, COMMUN MATH PHYS, V252, P189, DOI 10.1007-s00220-004-1187-344
CONFORMAL MODULI AND b-c PICTURES FOR NSR STRINGS
No full textWe explore the geometry of superconformal moduli of the NSR superstring theory in order to construct the consistent sigma-model for NSR strings, free of picture-changing complications. The sigma-model generating functional is constructed by the integration over the bosonic and fermionic moduli, corresponding to insertions of the vertex operators in scattering amplitudes. While the integration over the supermoduli leads to the standard picture-changing insertions, the integration over the bosonic moduli results in the appearance of picture-changing operators for the b-c fermionic ghosts with the ghost number -1. Important example of the b-c ghost pictures involves the vertex operators in integrated and unintegrated forms. We obtain the BRST-invariant expressions for the b-c picture-changing operators for open and closed strings and study some of their properties. We also show that the superconformal moduli spaces of the NSR theory contain the global singularities, leading to the phenomenon of ghost-matter mixing and the appearance of nonperturbative D-brane creation operators. © World Scientific Publishing Company.FRADKIN ES, 1985, NUCL PHYS B, V261, P1, DOI 10.1016-0550-3213(85)90559-0; FRIEDAN D, 1986, NUCL PHYS B, V271, P93; Gubser SS, 1998, PHYS LETT B, V428, P105, DOI 10.1016-S0370-2693(98)00377-3; KNIZHNIK VG, 1989, USP FIZ NAUK+, V159, P401, DOI 10.3367-UFNr.0159.198911a.0401; KOBA Z, 1969, NUCL PHYS B, VB 12, P517, DOI 10.1016-0550-3213(69)90071-6; Kogan II, 2003, INT J MOD PHYS A, V18, P1827, DOI 10.1142-S0217751X03013715; Maldacena J M, 1998, ADV THEOR MATH PHYS, V2, P231, DOI DOI 10.1023-A:1026654312961; OHTA N, 1986, PHYS REV D, V33, P1681, DOI 10.1103-PhysRevD.33.1681; OHTA N, 1986, PHYS LETT B, V179, P349; Polchinski J, 1995, PHYS REV LETT, V75, P4724, DOI 10.1103-PhysRevLett.75.4724; Polyakov D, 2002, PHYS REV D, V65, DOI 10.1103-PhysRevD.65.084041; VERLINDE E, 1987, PHYS LETT B, V192, P95, DOI 10.1016-0370-2693(87)91148-8; Witten E., 1998, ADV THEOR MATH PHYS, V2, P253, DOI DOI 10.1016-S0370-1573(99)00083-688
Gittersimulation einer zentrumssymmetrischen dreidimensionalen effektiven Theorie für SU(2) Yang-Mills
No full textWe present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of a gauge invariant kinetic term, spatial gauge fields and a potential for the Wilson line which includes a "fuzzy" bag term to generate non-perturbative fluctuations between Z(2) degenerate ground states. The model is studied in the limit where the gauge fields are set to zero as well as the full model with gauge fields. We confirm that, at moderately weak coupling, the "fuzzy" bag term leads to eigenvalue repulsion in a finite region above the deconfining phase transition which shrinks in the extreme weak-coupling limit. A non-trivial Z(N) symmetric vacuum arises in the confined phase. The effective potential for the Polyakov loop in the theory with gauge fields is extracted from the simulations including all modes of the loop as well as for cooled configurations where the hard modes have been averaged out. The former is found to exhibit a non-analytic contribution while the latter can be described by a mean-field like ansatz with quadratic and quartic terms, plus a Vandermonde potential which depends upon the location within the phase diagram. Other results include the exact location of the phase boundary in the plane spanned by the coupling parameters, correlation lengths of several operators in the magnetic and electric sectors and the spatial string tension. We also present results from simulations of the full 4D Yang-Mills theory and attempt to make a qualitative comparison to the 3D effective theory.Diese Arbeit präsentiert die Ergebnisse der Gittersimulation einer dreidimensionalen effektiven Theorie für eine SU(2) Eichtheorie bei endlichen Temperaturen. Die Theorie verwendet thermische Wilson Linien und den dreidimensionalen magnetischen Sektor als elementare Freiheitsgrade. Die Wirkung der effektiven Theorie respektiert alle Symmetrien der Eichtheorie in vier Dimensionen. Sie ist invariant unter lokalen SU(2) Eichtransformationen und zusätzlich invariant unter globalen Z(2) Transformationen, welche dem Abel'schem Zentrum der SU(2) Gruppe entsprechen. Sie enthält das Quadrat des dreidimensionalen Feldstärketensors, einen effektiven kinetischen Term der die Eichfelder an die Wilson Linien koppelt und das störungstheoretische Potential der Wilson Linien bis zur ersten Ordnung. Zusätzlich wird ein "fuzzy bag'' Term addiert, welcher einen Phasenübergang erzeugt und nicht-störungstheoretische Fluktuationen zwischen Z(2) symmetrischen Grundzuständen generiert. Wir untersuchen die Theorie sowohl im Grenzfall verschwindender Magnetfelder, als auch die volle Theorie in welcher dynamische Magnetfelder auftreten. Wir zeigen, dass die Theorie eine Phase mit spontan gebrochener Z(2) Symmetrie besitzt in welcher der Polyakov Loop einen nicht-verschwindenden Wert hat. In Analogie zur Quantenchromodynamik entspricht dies einer Aufhebung des Quark-Confinement. Wir bestimmen das Phasendiagramm der Theorie und ermitteln die Ordnung des Phasenübergangs an verschiedenen Stellen der Phasengrenze mittels Korrelationsfunktionen und des Skalenverhaltens der Suszeptibilität. Wir zeigen dass im Bereich mittel schwacher Kopplung nahe der Phasengrenze in der Symmetrie-gebrochenen Phase der "fuzzy bag'' Term Eigenwert Repulsion erzeugt, welche im Grenzfall extrem schwacher Kopplung verschwindet. Wir zeigen dass ein nicht-triviales Z(2) symmetrisches Vakuum existiert. Für die volle Theorie mit Eichfeldern untersuchen wir die räumliche String Spannung und zeigen dass magnetische Observablen vom elektrischen Sektor nur schwach beeinflusst werden. Desweiteren bestimmen wir das effektive Potential des Polyakov Loop, sowohl für den Fall dass alle Fourier Moden betrachtet werden, als auch für "gekühlte'' Konfigurationen ("Block Spins'') in welchen das Polyakov Loop Feld über kleine Volumina gemittelt wird, wodurch kurzreichweitige Fluktuationen unterdrückt werden. Qualitative Vergleiche mit der vierdimensionalen Eichtheorie zeigen dass das Verhalten des Block Spin Potentials in der dreidimensionalen Theorie mit der vierdimensionalen Theorie übereinstimmt
Geração radiativa de repulsão vetorial para quarks leves
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Física, Florianópolis, 2014Abstract: We apply a non-perturbative analytical method, known as the Optimized PerturbationTheory (OPT), to the Polyakov-Nambu-Jona-Lasinio (PNJL) model in order to investigate physical quantities associated with the QCD phase transitions. We consider the Taylor expansion of the pressure in powers of µ/T obtaining the second cumulant (c2) which is associated to the quark number susceptibility. We discuss how the OPT nite Nc radiative (quantum) corrections induce a contribution to the pressure which behaves as a vector repulsion even when such a channel is absent in the original classical potential. Our results are then compared with the ones furnished by lattice QCD simulations and by the large-Nc approximation showing that, physically, the OPT results resemble those furnished by the latter approximation when a repulsive vector channel is explicitly included in the classical potential. In this case, both approximations fail to correctly describe the Stefan-Boltzmann limit at high temperatures. We discuss how this problem can be circumvented by taking the couplings to be temperature dependent so as to simulate the phenomenon of asymptotic freedom. Since this is the first time the OPT is applied to the PNJL we also discuss many technicalities associated with the evaluation of two loop (exchange) diagrams.Neste trabalho o método analítico não perturbativo conhecido como Teoria de Perturbação Otimizada (OPT) é aplicada ao modelo de Polyakov-Nambu-Jona-Lasinio (PNJL) para que quantidades físicas, associadas com as transições de fase da QCD, possam ser calculadas. A expansão da pressão em potências de µ/T é considerada para obter o segundo cumulante (c2) que é uma quantidade relacionada com a susceptibilidade do número de quarks. Primeiramente discutimos como as correções radiativas de Nc finito geradas pela OPT produzem uma contribuição que se comporta como um termo vetorial repulsivo mesmo quando este tipo de canal está ausente no potencial clássico original. Em seguida, nossos resultados são comparados com aqueles fornecidos pelas simulações na rede e também pela aproximação de Nc grande(LN). Fisicamente, os resultados da OPT são similares aqueles fornecidos pela aproximação LN quando um canal vetorial repulsivo é explicitamente incluido no potencial clássico. Neste caso, nenhuma destas aproximações analíticas produz corretamente o limite de Stefan Boltzmann para altas temperaturas. Contudo, nossos resultados sugerem como estes problemas podem ser contornados tomando-se as constantes de acoplamento como sendo dependentes da temperatura, de maneira que o fenômeno da liberdade assimptótica possa ser simulado. Esta é a primeira vez que a OPT é aplicada ao modelo de PNJL e por isto vários aspectos técnicos relacionados com o cálculo de diagramas de dois laços são também aqui apresentados
POLYAKOV LOOPS AND FINITE-SIZE EFFECTS OF HADRON MASSES IN FULL LATTICE QCD
No full textPolyakov type loops are responsible for the difference between quenched and unquenched finite size effects on the QCD mass spectrum. With a numerical simulation, using appropriate sea quark spatial boundary conditions, we show that we can align the phases of spatial Polyakov loops in a predefined direction. Starting from these results, we propose a procedure to minimize fluctuations due to these effects in meson propagators. © 1995
The Exact N-Point Generating Function In Polyakov -Burgers Turbulence
No full textWe find the exact N-point generating function in Polyakov's approach to Burgers turbulence. 1- Introduction A theoretical understanding of turbulence has eluded physicists for a long time. Recently Polyakov [1] has offerd a field theoretic method for deriving of the probability distribution or density of states in (1+1)-dimensional turbulent systems. Polyakov formulates a new method for analyzing the inertial range correlation functions based on the two important ingredients in field theory and statistical physics namely the operator product expansion (OPE) and anomalies. Despite existence of many field theoretic approaches to turbulence [2,3,4], it appears that this new approach is more promising. Polyakov argues that in the limit of high Reynold's number because of existence of singularities at coinciding point, dissipation remains finite and all sublleading terms give vanishing contributions in the inertial range. By develop the OPE one finds the leading singularities and can show ..
Improved implementation of the Alicki–Van Ryn nonclassicality test for a single particle using Si detectors
No full textRecently a test of nonclassicality for a single qubit was proposed [R. Alicki and N. Van Ryn, J. Phys. A: Math. Theor. 41, 062001 (2008)]. We present an optimized experimental realization of this test leading to a 46 standard deviation violation of classicality. This factor of 5 improvement over our previous result was achieved by moving from the infrared to the visible where we can take advantage of higher efficiency and lower noise photon detectors
SU(N) gauge theories in Polyakov gauge on the torus
No full textWe investigate the Abelian projection with respect to the Polyakov loop operator for SU ( N ) gauge theories on the four torus. The gauge fixed A 0 is time-independent and diagonal. We construct fundamental domains for A 0 . In sectors with non-vanishing instanton number such gauge fixings are always singular. The singularities define the positions of magnetically charged monopoles, strings or walls. These magnetic defects sit on the Gribov horizon and have quantized magnetic charges. We relate their magnetic charges to the instanton number
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