119039556
A Covariant Approach to Noncommutative M5-Branes
We briefly review how to discuss noncommutative (NC) M5-branes and intersecting NC M5-branes from κ-invariance of an open supermembrane action with constant three-form fluxes. The κ-invariance gives rise to possible Dirichlet brane configurations. We shortly summarize a construction of projection operators for NC M5-branes and some intersecting configurations of NC M5-branes. A strong flux limit of them is also discussed.
119327427
Hidden Yangian symmetry in sigma model on squashed sphere
We discuss a hidden symmetry of a two-dimensional sigma model on a squashed S3. The SU(2) current can be improved so that it can be regarded as a flat connection. Then we can obtain an infinite number of conserved non-local charges and show the Yangian algebra by directly checking the Serre relations. This symmetry is also deduced from the coset structure of the squashed sphere. The same argument is applicable to the warped AdS3 spaces by the double Wick rotations.
2088281
A tunneling picture of dual giant Wilson loop
We further discuss a rotating dual giant Wilson loop (D3-brane) solution constructed in Lorentzian AdS by Drukker et al. The solution is shown to be composed of a dual giant Wilson loop and a dual giant graviton by minutely examining its shape. Hence it may be supposed that the dual gauge-theory operator should be a k-th symmetric Wilson loop with insertions of dual giant graviton operators. To give a convincing argument for this observation, the classical action of the solution should be evaluated in Euclidean signature. For this purpose we perform a Wick rotation to the Lorentzian solution by following the tunneling prescription and obtain Euclidean solutions attaching to a circle or a straight line on the AdS boundary. The classical action contains a logarithmic divergence which is proportional to the R-charge. It is consistent with the correlation function of the dual giant graviton operators. Because of ambiguities concerning regularization, finite terms of the action do not lead to conclusive evidence. However we may expect that the ambiguities would cancel by subtracting the action of the D3-brane with a straight-line boundary from that with a circular boundary. It is really shown that the difference is consistent with the expectation value of the k-th symmetric Wilson loop. Although our analysis does not specify the unique dual gauge-theory operator, we discuss possible candidates implied by the D3-brane computation.
18362159
Partition function and open/closed string duality in type IIA string theory on a pp-wave
Abstract We discuss partition functions of N =(4,4) type IIA string theory on the pp-wave background. This theory is shown to be modular invariant. The boundary states are constructed and possible D-brane instantons are classified. Then we calculate cylinder amplitudes in both closed and open string descriptions and check the open/closed string duality. Furthermore we consider general properties of modular invariant partition functions in the case of pp-waves.
15711173
Non-relativistic string and D-branes on AdS5 × S5 from semiclassical approximation
We show that non-relativistic actions of string and D-branes on AdS5???S5 can be reproduced as a semiclassical approximation of the string and D-brane actions around static 1/2 BPS configurations. This is contrastive to the Penrose limit. For example, the pp-wave string can be recaptured as a semiclassical approximation around a 1/2 BPS particle rotating at the velocity of light. We argue that small deformation of a straight Wilson line would give a composite operator in the gauge-theory side that corresponds to a semiclassical state of the non-relativistic string, according to the semiclassical interpretation.
119324390
Hybrid classical integrable structure of squashed sigma models - a short summary
We give a short summary of our recent works on the classical integrable structure of two-dimensional non-linear sigma models defined on squashed three-dimensional spheres. There are two descriptions to describe the classical dynamics, 1) the rational description and 2) the trigonometric description. It is possible to construct two different types of Lax pairs depending on the descriptions, and the classical integrability is shown by computing classical r/s-matrices satisfying the extended Yang-Baxter equation in both descriptions. In the former the system is described as an integrable system of rational type. On the other hand, in the latter it is described as trigonometric type. There exists a non-local map between the two descriptions and those are equivalent. This is a non-local generalization of the left-right duality in principal chiral models.
120765038
Attempts in detection of neutrons on So-called cold nuclear fusion
Neutron emissions from electrolysis of D 2 O with palladium and palladium-titanium electrodes as well as from pressurized D 2 gas with titanium alloys have been measured. The neutron detector system was so designed to have very low background condition. Neutron-γ separation technique using liquid scintillator was applied to obtain essentially no γ ray background condition for neutron counting. Special care was taken to stabilize the detection system using event-by-event data recording. No significant signal of neutron emission was observed. Upper limits of emission probability of neutron have been determined to be 6×10 -3 s -1 , 1×10 -2 s -1 , and 2.3×10 -2 s -1 for Pd electrode, Pd-Ti electrode, and pressurized gas systems. These values are orders of magnitude lower than that presented by Jones paper (0.4 s -1 ).
118435601
Vanishing thermal mass in the strongly coupled QCD/QED medium
In this paper we perform a nonperturbative analysis of a thermal quasifermion in thermal QCD/QED by studying its self-energy function through the Dyson-Schwinger equation with the hard-thermal-loop resummed improved ladder kernel. Our analysis reveals several interesting results, some of which may force us to change the image of the thermal quasifermion: (1) The thermal mass of a quasifermion begins to decrease as the coupling gets stronger and finally disappears in the strong coupling region,(2) the imaginary part of the chiral invariant mass function (i.e., the decay width of the quasifermion) persists to have $O(g^2 T \log (1/g))$ behavior. Present results suggest that in the recently produced strongly coupled quark-gluon-plasma, the thermal mass of a quasifermion should vanish. We also briefly comment on evidence of the existence of a massless, or an ultrasoft mode.
119480216
Chiral Phase Transitions in QED at Finite Temperature Dyson-Schwinger Equation Analysis in the Real Time Hard-Thermal-Loop Approximation
In order to clarify the essential thermal effects that govern the chiral phase transition at finite temperature, we investigate, in the real-time thermal QED, the consequences of the hard-thermal-loop (HTL) resummed Dyson-Schwinger equation for the physical fermion mass function ΣR. Since ΣR is the mass function of an “unstable” quasi-particle in thermal field theories, it necessarily has non-trivial imaginary parts, together with non-trivial wave function renormalization constants. Analyses so far have completely disregarded this fact, despite it being one of the basic outcomes of thermal field theory. The “approximation”, which ignores the imaginary parts of ΣR, gives (non-trivial) constraint equations to be solved simultaneously. For this reason, this approximation cannot be applied consistently except in the trivial case, ΣR = 0. In the present analysis we correctly take this fact into account, and study, in the ladder approximation, the effect of the HTL resummed gauge boson propagator. Our results obtained using numerical analysis, reveal two facts: i) the chiral phase transition is of second order, since the fermion mass is dynamically generated at a critical value of the temperature Tc, or at a critical coupling constant αc, without any discontinuity; and ii) the critical temperature Tc at a fixed value of α is significantly lower than that obtained previously, which means that the restoration of chiral symmetry occurs at a lower temperature than previously expected. The second fact shows the importance of correctly incorporating the essential thermal effect into the analysis of the chiral phase transition. A procedure for taking account of the gauge invariance in the present approximation is also discussed.
121806959
Measurements of interaction cross sections for light neutron-rich nuclei at relativistic energies and determination of effective matter radii
Abstract We measured the interaction cross sections ( σ I ) of 10,11B, 12–20C, 14–23N, 16–24O and 18–26F on carbon targets at energies of around 950 A MeV. We then deduced the effective matter radii of the nuclei by a Glauber-model analysis. Based on the assumption of a core plus a valence neutron structure, we applied a Glauber-model analysis for a few-body system adapted for nuclei with an odd neutron number. We also deduced the effective nucleus-matter densities as well as some spectroscopic information for selected nuclei. Evidence for a one-neutron halo structure was found for 22N, 23O and 24F, as well as 19C.
120768754
Nonlinear dynamics with sextupoles in low-emittance light source storage rings
Abstract An analysis is made of the nonlinear particle motions arising from sextupoles in low-emittance light source rings. By employing the single-resonance approximation to the Hamiltonian expanded into harmonics, boundaries of the stable motion brought about by 1st- and 3rd-order resonances are calculated analytically. These are used together with the second-order tune shifts with amplitude as guidelines of the analysis and of the optimization of sextupoles to improve the dynamic aperture. The application is made to two typical lattices of the light source rings, the Chasman-Green and the triple-bend achromat lattice, to pursue the lattice dependence of the nonlinear characteristics. Apart from the cases where the stability is determined by the lowest-order resonances, studies using particle tracking indicate that the motion is very often driven by higher-order resonances for which further considerations are required. Two approaches are discussed in this context. One is to interpret the phenomena as a combined effect of the lowest-order resonances, which is verified numerically by a fictitious tracking. Another is the perturbative method. The theory developed by Poincare and von Zeipel is used to analyze the horizontal dynamics, which is worked up to 4th order in amplitude. Examples that satisfactorily reproduce the phase-space structure are shown, although it is also found that perturbations of many of the sextupoles required for these low-emittance rings are even higher than 4th order.