A solution to the 4-tachyon off-shell amplitude in cubic string field theory

We derive an analytic series solution of the elliptic equations providing the 4-tachyon off-shell amplitude in cubic string field theory (CSFT). From such a solution we compute the exact coefficient of the quartic effective action relevant for time dependent solutions and we derive the exact coefficient of the quartic tachyon coupling. The rolling tachyon solution expressed as a series of exponentials $e^t$ is studied both using level-truncation computations and the exact 4-tachyon amplitude. The results for the level truncated coefficients are shown to converge to those derived using the exact string amplitude. The agreement with previous work on the subject, both on the quartic tachyon coupling and on the CSFT rolling tachyon, is an excellent test for the accuracy of our off-shell solution.Comment: 26 pages, 5 figure

Remarks on the geometrical properties of semiclassically quantized strings

We discuss some geometrical aspects of the semiclassical quantization of string solutions in type IIB Green–Schwarz action on ADS5xS5 We concentrate on quadratic fluctuations around classical configurations, expressing the relevant differential operators in terms of (intrinsic and extrinsic) invariants of the background geometry. The aim of our exercise is to present some compact expressions encoding the spectral properties of bosonic and fermionic fluctuations. The appearing of non-trivial structures on the relevant bundles and their role in concrete computations are also considered. We corroborate the presentation of general formulas by working out explicitly a couple of relevant examples, namely the spinning string and the latitude BPS Wilson loop

The Final Fate of the Rolling Tachyon

We propose an alternative interpretation of the boundary state for the rolling tachyon, which may depict the time evolution of unstable D-branes in string theory. Splitting the string variable in the temporal direction into the classical part, which we may call "time" and the quantum one, we observe the time dependent behaviour of the boundary. Using the fermion representation of the rolling tachyon boundary state, we show that the boundary state correctly describes the time-dependent decay process of the unstable D-brane into a S-brane at the classical level.Comment: 9 pages, revte

Generalized quark-antiquark potential at weak and strong coupling

We study a two-parameter family of Wilson loop operators in N=4 supersymmetric Yang-Mills theory which interpolates smoothly between the 1/2 BPS line or circle and a pair of antiparallel lines. These observables capture a natural generalization of the quark-antiquark potential. We calculate these loops on the gauge theory side to second order in perturbation theory and in a semiclassical expansion in string theory to one-loop order. The resulting determinants are given in integral form and can be evaluated numerically for general values of the parameters or analytically in a systematic expansion around the 1/2 BPS configuration. We comment about the feasibility of deriving all-loop results for these Wilson loops.Comment: 43 pages: 15 comprising the main text and 25 for detailed appendice

The Subleading Term of the Strong Coupling Expansion of the Heavy-Quark Potential in a N=4\mathcal N=4 Super Yang-Mills Plasma

Applying the AdS/CFT correspondence, the expansion of the heavy-quark potential of the ${\cal N}$ supersymmetric Yang-Mills theory at large $N_c$ is carried out to the sub-leading term in the large 't Hooft coupling at nonzero temperatures. The strong coupling corresponds to the semi-classical expansion of the string-sigma model, the gravity dual of the Wilson loop operator, with the sub-leading term expressed in terms of functional determinants of fluctuations. The contributions of these determinants are evaluated numerically.Comment: 17 pages in JHEP3, typos fixed, updated version to be published in JHE

Precision calculation of 1/4-BPS Wilson loops in AdS(5) x S-5

We study the strong coupling behaviour of 1/4-BPS circular Wilson loops (a family of “latitudes”) in N=4 Super Yang-Mills theory, computing the one-loop corrections to the relevant classical string solutions in AdS5 ×S5. Supersymmetric localization provides an exact result that, in the large ’t Hooft coupling limit, should be reproduced by the sigma-model approach. To avoid ambiguities due to the absolute normalization of the string partition function, we compare the ratio between the generic latitude and the maximal 1/2-BPS circle: any measure-related ambiguity should simply cancel in this way. We use the Gel’fand-Yaglom method with Dirichlet boundary conditions to calculate the relevant functional determinants, that present some complications with respect to the standard circular case. After a careful numerical evaluation of our final expression we still find disagreement with the localization answer: the difference is encoded into a precise “remainder function”. We comment on the possible origin and resolution of this discordance

Markers of Liver Function as Potential Prognostic Indicators of SARS-CoV-2 infection: A Retrospective Analysis during the First and Second Waves of COVID-19 Pandemic

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is known to cause a predominant respiratory disease, although extrapulmonary manifestations can also occur. One of the targets of Coronavirus disease 2019 (COVID-19) is the hepatobiliary system. The present study aims to describe the correlation between the increase of liver damage markers (i.e. alanine aminotransferase [ALT], aspartate aminotransferase [AST], total bilirubin [TB]) and COVID-19 outcomes (i.e., in-hospital mortality [IHM] and intensive care unit [ICU] transfer). Methods: All patients with confirmed SARS-CoV-2 infection admitted to the Infectious Diseases Unit of the St. Anna University-Hospital of Ferrara from March 2020 to October 2021 were retrospectively included in this single-centre study. ALT, AST and TB levels were tested in all patients and IHM or ICU transfer were considered as main outcomes. Co-morbidities were assessed using Charlson Comorbidity Index. Results: A total of 106 patients were retrieved. No hepatic marker was able to predict IHM, whereas all of them negatively predicted ICU transfer (ALT: OR 1.005, 95%CI 1.001-1.009, p= 0.011; AST: OR 1.018, 95%CI 1.006-1.030, p= 0.003; TB: OR 1.329, 95%CI 1.025-1.724, p= 0.032). Age was the only parameter significantly related to mortality. Conclusions: The present study, by correlating liver damage markers with COVID-19 outcome, showed that an increase of ALT, AST and TB predicted patients' severity, although not mortality

Applications of Thirring Model to Inhomogenous Rolling Tachyon and Dissipative Quantum Mechanics

We study the rolling tachyon and the dissipative quantum mechanics using the Thirring model with a boundary mass. We construct a boundary state for the dissipative quantum system in one dimension, which describes the system at the off-critical points as well as at the critical point. Then we extend the Thirring model with a boundary mass in order to depict the time evolution of an unstable D-branes with one direction wrapped on a circle of radius $R$, which is termed the inhomogeneous rolling tachyon. The analysis based on the Thirring model shows that the time dependent evolution of the inhomogeneous tachyon is possible only when $\frac{2}{\sqrt{3}}< R < 2$.Comment: 19 pages, 2 figures, This work supersedes the previous one, arXiv:0705.3930 [hep-th

Twist operators in N=4 beta-deformed theory

In this paper we derive both the leading order finite size corrections for twist-2 and twist-3 operators and the next-to-leading order finite-size correction for twist-2 operators in beta-deformed SYM theory. The obtained results respect the principle of maximum transcendentality as well as reciprocity. We also find that both wrapping corrections go to zero in the large spin limit. Moreover, for twist-2 operators we studied the pole structure and compared it against leading BFKL predictions.Comment: 17 pages; v2: minor changes, references adde

Quark-antiquark potential in AdS at one loop

We derive an exact analytical expression for the one-loop partition function of a string in AdS_5xS^5 background with world-surface ending on two anti-parallel lines. All quantum fluctuations are shown to be governed by integrable, single-gap Lame' operators. The first strong coupling correction to the quark-antiquark potential, as defined in N=4 SYM, is derived as the sum of known mathematical constants and a one-dimensional integral representation. Its full numerical value can be given with arbitrary precision and confirms a previous result.Comment: 16 pages. Typos corrected, minor change