Narrow Results

This meeting produces another evidence that present parallel computers are (a) real instruments of computational physics, (b) largely in the hands of still-pioneers, (c) efficiently promoted by basic research groups with large-scale computational needs. Progress in parallel computing is carried by two types of such groups, that either follow the build-it-yourself or the early-use strategies. In this contribution, we describe, as an example to the second approach, the Wuppertal university pilot project in applied parallel computing. We report in particular about one of our key applications in theoretical particle physics on the Connection Machine CM-2: a high statistics computer experiment to determine the static quark-antiquark potential from quenched quantum chromodynamics.

A detailed investigation of the temperature dependence of the spatial string tension σ_s in SU(2) gauge theory is presented. A sustained performance of 3 GFLOPS on a 64K Connection Machine CM-2 equivalent has been achieved. Scaling of σ_s between β = 2.5115 and β = 2.74, on large lattices, is demonstrated. Below the critical temperature, T_c, σ_s remains constant. For temperatures larger than 2T_c the temperature dependence can be parametrized by σ_s(T) = (0.369 ± 0.014)²g⁴(T)T², where g(T) is a 2-loop running coupling constant with the scale parameter determined as Λ_T = (0.076 ± 0.013)T_c.

We are studying quantum corrections in the earlier proposed string theory based on worldsheet action which measures the linear sizes of the surfaces. At classical level the string tension is equal to zero and as it was demonstrated in the previous studies one loop correction to the classical worldsheet action generates Nambu–Goto area term, that is nonzero string tension. We extend this analysis computing the worldsheet effective action in the second order of the loop expansion.

We are studying quantum corrections in the earlier proposed string theory based on worldsheet action which measures the perimeter of the surface. At the classical level the string tension is equal to zero and we demonstrate that one and two-loop corrections to the classical worldsheet action generates Nambu–Goto area term, that is nonzero string tension.

I review the analysis of (2+1)-dimensional Yang-Mills (YM₂₊₁) theory via the use of gauge-invariant matrix variables. The vacuum wavefunction, string tension, the propagator mass for gluons, its relation to the magnetic mass for YM₃₊₁ at nonzero temperature and the extension of our analysis to the Yang-Mills-Chern-Simons theory are discussed. A possible extension to 3 + 1 dimensions is also briefly considered.

We show that it is possible to formulate string theory as a “Galileon string theory”. The Galileon field $\chi$ enters in the definition of the integration measure in the action. Following the methods of the modified measure string theory, we find that the final equations are again those of the sigma-model. Moreover, the string tension appears again as an additional dynamical degree of freedom. At the same time, the theory satisfies all requirements of the Galileon higher derivative theory at the action level while the equations of motion are still of the second-order. A Galileon symmetry is displayed explicitly in the conformal string worldsheet frame. Also, we define the Galileon gauge transformations. Generalizations to branes with other modified measures are discussed.

In our study, we delved into the profound ramifications of string tension on the collapse of a string fluid, culminating in the formation of a black hole within the realm of $f(R)$ gravity. A string fluid is a perfect fluid model, each whose particle admits a radially stretched string. The outer region for the collapsing object is assumed to be the Schwarzschild spacetime, while the fluid collapses in the internal region are supposed to be Friedman–Robertson–Walker spacetime. The junction conditions are developed leading to gravitational mass and energy. The time frame for apparent horizon and singularity formation was estimated, showing a black hole as the outcome. String tension emerged as a pivotal factor in prolonging horizon creation. Our findings illuminate the relation among $f(R)$ gravity, string tension, and collapse dynamics, enriching our understanding of cosmic phenomena.

We have developed an equation of state for strongly interacting quark–gluon plasma (QGP) in the framework of strongly coupled plasma with appropriate modifications to take account of color and flavor degrees of freedom and the interactions among themselves. For this purpose we used the effective potential to improve the plasma parameter (Γ) by correcting the full Cornell potential with a dielectric function embodying the effects of the deconfined medium and not its Coulomb part alone and obtain the equation of state in terms of Γ. Our results on thermodynamic observables viz. pressure, energy density, speed of sound etc. nicely fit to the results of lattice equation of state for gluon, massless as well massive flavored plasma. We have then employed our equation of state to estimate the quarkonium suppression in an expanding QGP produced in the relativistic heavy-ion collisions. We have found that our predictions matches with the recent PHENIX data on the centrality dependence of J/ψ suppression in Au+Au collisions at BNL RHIC within the limit of other uncertainties. We have also predicted for the ϒ suppression in Pb+Pb collisions at LHC energy which could be tested in the ALICE experiments at CERN LHC.

In this paper, we consider the Hamiltonian analysis of Yang–Mills theory and some variants of it in three space–time dimensions using the Schrödinger representation. This representation, although technically more involved than the usual covariant formulation, may be better suited for some nonperturbative issues. Specifically for the Yang–Mills theory, we explain how to set up the Hamiltonian formulation in terms of manifestly gauge-invariant variables and set up an expansion scheme for solving the Schrödinger equation. We review the calculation of the string tension, the Casimir energy and the propagator mass and compare with the results from lattice simulations. The computation of the first set of corrections to the string tension, string breaking effects, extensions to the Yang–Mills–Chern–Simons theory and to the supersymmetric cases are also discussed. We also comment on how entanglement for the vacuum state can be formulated in terms of the BFK gluing formula. This paper concludes with a discussion of the status and prospects of this approach.

The inclusive spectrum of the charged particles, $\pi$⁰- and $\eta$-mesons produced in the pp collisions at LHC energies were analyzed by fitting them with exponential functions. It was found the spectra were composed of several p${}_T$ regions, which could be characterized by the length of the regions $L_K^c$ and two free fitting parameters $a_K^c$ and $b_K^c$. The study of the $L_K^c$ dependences of the parameters $a_K^c$ and $b_K^c$ and of the energy dependencies of the $L_K^c$, $a_K^c$ and $b_K^c$ showed that the regions can be classified into two groups depending on the values of the $L_K^c$, $a_K^c$ and $b_K^c$. The values of the $L_K^c$ and $b_K^c$ for the first group don’t depend on colliding energy and the type of the particles (though the values of $a_K^c$ increase linearly with energy) whereas the characteristics in the second group of regions show strong dependencies. It was found that the ratio of the length for the $\eta$-mesons to one for the $\pi$⁰-mesons is approximately equal to the ratio of their mass: $〈L_{\eta }〉:〈L_{{\pi }^0}〉\cong m_{\eta }:m_{{\pi }^0}$. Assuming that the values of the $L_K^c$ are directly proportional to the string tension the result could be considered as evidence in favor of parton string fragmentation dynamics. The increase in the lengths for the $\eta$-mesons’ regions is accompanied by an increase of the values for the parameter $b_k^c$. It can mean that the $\eta$-mesons were produced at smaller values of ${\alpha }_S$ compared with that for $\pi$⁰-mesons. The results show that for the first group of regions the lengths of the regions are $\sim$3–5 times greater than the lengths of neighboring, lower p${}_T$ regions. For the second group of regions the lengths of the regions are $\sim$1–2 times greater than the lengths of neighboring lower p${}_T$ region. In the framework of the string fragmentation and hadronization dynamics, this could mean that the particles in the group $I$ of regions are produced through previous-generation strings decays into $\sim$3–5 strings while those in group $II$ originate from previous-generation strings decays into $\sim$2 strings.

Recently we hear more and more physicists saying, ‘spacetime is doomed’, ‘spacetime is a mirage’, the ‘end of spacetime’, ‘spacetime is not fundamental but emergent’ etc. “Henceforth space by itself and time by itself are doomed to fade into the mere shadows, and only a union of the two will preserve an independent reality.” – 1908 Hermann Minkowski. We have come full circle from the time of Minkowski's 1908 statement to the brink of an imminent new age of discovery. The basis of our understanding of the natural world has evolved in modern times from Newtonian Mechanics to the 2nd regime of Quantum Mechanics; and now to the threshold of a 3rd regime - Unified Field Mechanics (UFM). The Planck scale stochastic quantum realm can no longer be considered the ‘basement’ or fundamental level of reality. As hard as quantum reality was to imagine so is the fact that the quantum domain is a manifold of finite radius; and that the ‘sacrosanct - indelible’ Quantum Uncertainty Principle can now be surmounted. For decades main stream physicists have been stymied by efforts to reconcile General Relativity with Quantum Mechanics. The stumbling block lies with the two theories conflicting views of space and time: For quantum theory, space and time offer a fixed backcloth against which particles move. In Einstein's relativities, space and time are not only inextricably linked, but the resultant spacetime is warped by the matter within it. In our nascent UFM paradigm for arcane reasons the quantum manifold is not the regime of integration with gravity; it is instead integrated with the domain of the unified field where the forces of nature are deemed to unify. We give a simplistic survey of the fundamental premises of UFM and summarize experimental protocols to falsify the model at this stage of the paradigm's development.

HÉCTOR A.A brief introductory survey of Unified Field Mechanics (UFM) is given from the perspective of a Holographic Anthropic Multiverse cosmology in 12 ‘continuous-state’ dimensions. The paradigm with many new parameters is cast in a scale-invariant conformal covariant Dirac polarized vacuum utilizing extended HD forms of the de Broglie-Bohm and Cramer interpretations of quantum theory. The model utilizes a unique form of M-Theory based in part on the original hadronic form of string theory that had a variable string tension, T_S and included a tachyon. The model is experimentally testable, thus putatively able to demonstrate the existence of large-scale additional dimensionality (LSXD), test for QED violating tight-bound state spectral lines in hydrogen ‘below’ the lowest Bohr orbit, and surmount the quantum uncertainty principle utilizing a hyperincursive Sagnac Effect resonance hierarchy.