Filetype
We explore the possibilities of using the complex Langevin equation to Monte Carlo generate configurations of gauge theories with static charges present in the action. Successful results are obtained for systems that possess nontrivial saddle-point (classical) solutions. For that reason the algorithm works impressively for two-dimensional U(1) in the entire β-range whereas for three- and four-dime
From the 1880s until the ban of this practice in the 1970s, German vacationers built sandcastles, some of which were artfully decorated and awarded prizes in competitions by the spa administrations. Research regards this as a manifestation of a ‘typical German’ national character. The article counters this approach with an interpretation that understands sandcastles as metaphors for typical charac
By using the Langevin equation with complex action it is possible to generate (complex) configurations in the charged sector of gauge theories. We test the algorithm in the case of two-dimensional U(1) gauge theory and are able to measure the string tension with great precision and modest use of computer time for a separation of the charged particles where a conventional Wilson loop would have a v
Three-dimensional compact U(1) is studied on a 16×32×16 lattice with emphasis on roughening around the crossover region. Configurations including two static charges are generated using the dual formulation of the theory. In this way the flux patterns between the charges are mapped out. Very convincing evidence for roughening is found. In particular we show that the average transverse spread of the
We have measured the lattice size dependence of the lightest glueball mass in SU(2) and SU(3) gauge theory at =2.2 and 2.3 [SU(2)] and =6.0 [SU(3)]. We observe an increase in the glueball mass when the lattice size shrinks below a critical value. The magnitude of this length scale, which we interpret as the physical size of the glueball, is roughly the same for SU(2) and SU(3) when expressed in un
Microembolization is common after coronary interventions, and therefore this MRI study aimed to quantify the effect of coronary microembolization on left ventricular (LV) function. The left anterior descending artery (LAD) was selectively catheterized in an XMR suite (Philips Medical Systems, Best, The Netherlands) in eight pigs to deliver MR contrast media to measure the LAD territory using first
The adjoint (gluon) string tension in SU(2) lattice gauge theory has been found to be (8/3) times the corresponding fundamental (quark) string tension. This fact strongly favors the Lund-fragmentation-model prescription of treating hard gluons as kinks in the quark string.
The static potentials from bosonic string models are examined to the two-loop level. Available MC data for 4-dimensional SU(3) are in approximate agreement with the universal leading order predictions but fail to reproduce the Nambu string when the two-loop terms are included in the analysis. We also confront Nambu string model predictions for Tc σ with SU(2), SU(3) and SU(N → ∞) MC data. In the S
By Monte Carlo calculations on a 124 lattice we investigate four-dimensional SU(2) lattice gauge theory with respect to the conjecture that at large distances this theory reduces approximately to two-dimensional SU(2) lattice gauge theory. We find good numerical evidence for this conjecture. As a by-product we also measure the SU(2) string tension and find reasonable agreement with scaling. The "a
We study 3-dimensional SU(2) lattice gauge theory with respect to dimensional reduction. By Monte Carlo calculations we find that this reduction is valid to a good approximation (within ≈10%). The adjoint string tension is found to scale approximately. We also compare the adjoint string tension with a string theory.
In the hamiltonian formulation of fermions coupled to external gauge fields, the axial anomaly has a simple physical interpretation in terms of level shifting at the top of the Dirac sea. We apply this formalism to lattice QED in 1 + 1 and 3 + 1 dimensions, in order to study how the lattice regulation and small fermion mass affect the picture. For a simple choice of the E and B fields, it is possi
Cross sections for glueball production in hadron-induced reactions are estimated using the gluon-gluon fusion mechanism. For pp → θ(1700, JPC = 2++)X one finds σθ ∼ 2-10 mb in ISR-collider energy range. This cross section should give a clean experimental signal given the substantial KK decay mode observed in ψ → γθ.
Background: Calcium overload is a major cause of reperfusion myocardial injury. Multidetector computed tomography (MDCT) has been previously used in visualizing coronary artery calcium, but not calcium deposits in reperfused infarction. Purpose: To assess the ability of MDCT to 1) noninvasively visualize and characterize calcium deposits in reperfused infarcts, and 2) monitor regional wall swellin
SU(2) lattice gauge theory in three dimensions is investigated on a 162×32 lattice. We find that R>×T Wilson loops are well described by a simple string theory for β in the (approximate) scaling region.
Recent SU(3) lattice Monte Carlo data (244 and 164) are analyzed in terms of a simple string model. Good agreement is found. Observed similarities between SU(3) and three-dimensional SU(2) indicate that the string theory is indeed an effective one.
Existing bag-model calculations for the masses of lowest-lying glueball states are extended and reviewed and compared to the present lattice Monte Carlo calculations. The predicted spectra agree remarkably well.
We consider SU(2) lattice gauge theory in three dimensions. The Wilson loops are found to be well described by a simple string model in the approximate scaling region.
Phenomenological consequences of a recently improved and unified study of the lowestlying hadrons in the MIT Bag model are explored. In contrast to earlier fits we find the new values for the Bag constant B1/4(200-230 MeV) and the hadronic radii R0(≈3.2 GeV-1) to be consistent with present estimates of the gluon condensate {Mathematical expression}, the Hagedorn temperature TH and experimental hyp
An effective spin-dependent interaction Hamiltonian for low-lying gluon modes is calculated to O(±s) in the MIT bag model. We give expressions for the energy shifts of low-lying glueballs.
We present a consistent and unified study of the spectrum of low-lying mesons, baryons, and glueballs using the MIT bag model, incorporating several improvements in the model. We correct for the center-of-mass motion, use a running coupling αs(R), include self-energy terms for quarks and gluons confined in a cavity, and get the bag constant from a model of the QCD vacuum. Our fit to the meson and
