Simulation Results for U(1) Gauge Theory on Non-Commutative Spaces

We present numerical results for U(1) gauge theory in 2d and 4d spaces involving a non-commutative plane. Simulations are feasible thanks to a mapping of the non-commutative plane onto a twisted matrix model. In d=2 it was a long-standing issue if Wilson loops are (partially) invariant under area-preserving diffeomorphisms. We show that non-perturbatively this invariance breaks, including the subgroup SL(2,R). In both cases, d=2 and d=4, we extrapolate our results to the continuum and infinite volume by means of a Double Scaling Limit. In d=4 this limit leads to a phase with broken translation symmetry, which is not affected by the perturbatively known IR instability. Therefore the photon may survive in a non-commutative world

Area-preserving diffeomorphisms in gauge theory on a non-commutative plane: a lattice study

We consider Yang-Mills theory with the U(1) gauge group on a non-commutative plane. Perturbatively it was observed that the invariance of this theory under area-preserving diffeomorphisms (APDs) breaks down to a rigid subgroup SL(2,R). Here we present explicit results for the APD symmetry breaking at finite gauge coupling and finite non-commutativity. They are based on lattice simulations and measurements of Wilson loops with the same area but with a variety of different shapes. Our results are consistent with the expected loss of invariance under APDs. Moreover, they strongly suggest that non-perturbatively the SL(2,R) symmetry does not persist either.Comment: 28 pages, 15 figures, published versio

Area-preserving diffeomorphisms in gauge theory on a non-commutative plane: A lattice study

We consider Yang-Mills theory with the U(1) gauge group on a non-commutative plane. Perturbatively it was observed that the invariance of this theory under area-preserving diffeomorphisms (APDs) breaks down to a rigid subgroup SL(2,R). Here we present explicit results for the APD symmetry breaking at finite gauge coupling and finite non-commutativity. They are based on lattice simulations and measurements of Wilson loops with the same area but with a variety of different shapes. Our results are consistent with the expected loss of invariance under APDs. Moreover, they strongly suggest that non-perturbatively the SL(2,R) symmetry does not persist either

Simulation Results for U(1) Gauge Theory on Non-Commutative Spaces

We present numerical results for U(1) gauge theory in 2d and 4d spaces involving a non-commutative plane. Simulations are feasible thanks to a mapping of the non-commutative plane onto a twisted matrix model. In d=2 it was a long-standing issue if Wilson loops are (partially) invariant under area-preserving diffeomorphisms. We show that non-perturbatively this invariance breaks, including the subgroup SL(2,R). In both cases, d=2 and d=4, we extrapolate our results to the continuum and infinite volume by means of a Double Scaling Limit. In d=4 this limit leads to a phase with broken translation symmetry, which is not affected by the perturbatively known IR instability. Therefore the photon may survive in a non-commutative world

Simulation Results for U(1) Gauge Theory on Non-Commutative Spaces

We present numerical results for U(1) gauge theory in 2d and 4d spaces involving a non-commutative plane. Simulations are feasible thanks to a mapping of the non-commutative plane onto a twisted matrix model. In d=2 it was a long-standing issue if Wilson loops are (partially) invariant under area-preserving diffeomorphisms. We show that non-perturbatively this invariance breaks, including the subgroup SL(2,R). In both cases, d=2 and d=4, we extrapolate our results to the continuum and infinite volume by means of a Double Scaling Limit. In d=4 this limit leads to a phase with broken translation symmetry, which is not affected by the perturbatively known IR instability. Therefore the photon may survive in a non-commutative world

Total intravenous anaesthesia in endoscopic sinus-nasal surgery.

Aim of this randomized study (64 patients) was to improve the control of bleeding during functional endoscopic sinusal surgery by means of controlled hypotension achieved through either total intravenous anaesthesia using remifentanyl and propofol (27 patients), or inhaled using isoflurane and fentanyl (37 patients). The following parameters were monitored before administration of anaesthesia (T0), then after 15 (T1), and 30 minutes (T2): systolic, diastolic, and mean arterial pressure; heart rate; concentration of tele-exhaled carbon dioxide (PetCO2) and percentage of peripheral saturation of haemoglobin (SPO2); bleeding according to the Fromme-Boezaart scale at T2. Mean arterial pressure values were maintained between 60-70 mmHg throughout surgery. At T0, systolic arterial pressure, diastolic arterial pressure and mean arterial pressure values were seen to overlap in the two groups. Both types of anaesthesia were effective in reducing the pressure values of T0-T1 and T1-T2 trends (p<0.0001). Systolic arterial pressure at T1 is lower with total intravenous anaesthesia compared to isoflurane and fentanyl (p=0.02). PetCO2 and heart rate show a decreasing trend independently of the type of anaesthesia employed. In conclusion, the hypotensive effect of total intravenous anaesthesia and of isoflurane and fentanyl is equivalent, but only total intravenous anaesthesia is effective in reducing bleeding during functional endoscopic sinusal surgery