120150655
Quantum Currents in the Coset Space SU(2)/U(1)*
We propose a rational quantum deformed nonlocal currents in the homogeneous space , and in terms of it and a free boson field a representation for the Drinfeld currents of Yangian double at a general level is obtained. In the classical limit , the quantum nonlocal currents become parafermion, and the realization of Yangian double becomes the parafermion realization of current algebra.
12641558
Elasticity through Nanoscale Distortions in Periodic Surfactant-Templated Porous Silica under High Pressure
High-pressure infrared absorption spectroscopy is used to examine changes in local bonding upon hydrostatic compression in both ordered surfactant-templated mesoporous silica and sintered sol-gel silica with a goal of connecting atomic scale structural changes with variations in nanoscale periodicity. High-pressure IR absorption spectra are analyzed on the basis of a noncentral force model. It is found that the intertetrahedral bond angle and its distribution width in both the dense and the mesoporous silica decrease at elevated pressure up to 4 GPa. With increasing pressure above this value, decreases in the average bond angle and distribution width cease in the mesoporous silica, while they continue in the bulk material. The results suggest that in the mesoporous silica the nanometer length scale of the silica framework makes it energetically unfavorable to form high-density atomic scale structures at higher pressures ( >4 GPa). Instead, further compression of the mesoporous silica takes place by distortion of the periodic pore structures on the nanometer scale (deformation of pores). Surprisingly, upon the release of pressure, structural changes on both the nanometer and atomic length scales are reversible. The results suggest that reversible nanometer scale distortions in periodic porous materials can replace the irreversible atomic scale distortions observed in bulk amorphous silica.
126358134
Bosonic superconformal Toda theory and dressing symmetry
10580423
Ambiguities of the Seiberg-Witten map in the presence of matter field
The ambiguities of the Seiberg-Witten map for gauge field coupled with fermionic matter are discussed. We find that only part of the ambiguities can be absorbed by gauge transformation and/or field redefinition and thus are negligible. The existence of matter field makes some other part of the ambiguities difficult to be absorbed by gauge transformation or field redefinition.
118493069
Hidden symmetries for thermodynamics and emergence of relativity
Erik Verlinde recently proposed an idea about the thermodynamic origin of gravity. Though this is a beautiful idea which may resolve many long standing problems in the theories of gravity, it also raises many other problems. In this article I will comment on some of the problems of Verlinde’s proposal with special emphasis on the thermodynamical origin of the principle of relativity. It is found that there is a large group of hidden symmetries of thermodynamics which contains the Poincare group of the spacetime for which space is emergent. This explains the thermodynamic origin of the principle of relativity.
119542366
The origin of noncommutativity
Consistent boundary Poisson structures for open string theory coupled to background B-field are considered using the new approach proposed in hep-th/0111005. It is found that there are infinitely many consistent Poisson structures, each leads to a consistent canonical quantization of open string in the presence of background B-field. Consequently, whether the D-branes to which the open string end points are attached is noncommutative or not depends on the choice of a particular Poisson structure.
118416217
Pseudoscalar Goldstone bosons scattering off charmed baryons with chiral perturbation theory
Abstract We have systematically calculated the pseudoscalar Goldstone boson and charmed baryon scattering lengths to the third order with heavy baryon chiral perturbation theory. The scattering lengths can reveal the interaction of K Λ c , K Σ c , π Ω c , etc. For each channel, we take into account of the interaction between the external particle and every possible charmed baryon in the triplet, sextet, and excited sextet. We use dimensional regularization and modified minimal subtraction to get rid of the divergences in the loop-diagram corrections. We notice that the convergence of chiral expansion for most of the channels becomes better after we let the low energy constants absorb the analytic contributions of the loop-diagram corrections and keep the non-analytic terms only.
116940362
Measurement of the Probability of Gluon Splitting into Charmed Quarks in Hadronic Z Decays
We have measured the probability, $\overline{n}_{\rm{g} \rightarrow c\overline{c}}$, of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure $\overline{n}_{\rm{g} \rightarrow c\overline{c} } = [2.45 \pm 0.29 \pm 0.53]\$.
119214747
The windows for kinetically mixed Z′-mediated dark matter and the galactic center gamma ray excess
A bstractOne of the simplest hidden sectors with signatures in the visible sector is fermionic dark matter χ coupled to a Z′ gauge boson that has purely kinetic mixing with the standard model hypercharge. We consider the combined constraints from relic density, direct detection and collider experiments on such models in which the dark matter is either a Dirac or a Majorana fermion. We point out sensitivity to details of the UV completion for the Majorana model. For kinetic mixing parameter ϵ ≤ 0.01, only relic density and direct detection are relevant, while for larger ϵ, electroweak precision, LHC dilepton, and missing energy constraints become important. We identify regions of the parameter space of mχ, mZ ′ , dark gauge coupling and ϵ that are most promising for discovery through these experimental probes. We study the compatibility of the models with the galactic center gamma ray excess, finding agreement at the 2-3σ level for the Dirac model.
37916668
Renormalization of bilinear quark operators for overlap fermions
We present nonperturbative renormalization constants of fermionic bilinears on the lattice in the quenched approximation at {beta}=6.1 using an overlap [H. Neuberger, Phys. Lett. B 417, 141 (1998)] fermion action with hypercubic (HYP)-blocked links. We consider the effects of the exact zero modes of the Dirac operator and find they are important in calculating the renormalization constants of the scalar and pseudoscalar density. The results are given in the RI' and MS schemes and compared to perturbative calculations.
12149444
Observation of a Near-Threshold Enhancement in the p-anti-p Mass Spectrum from Radiative J/psi --> gamma-p-anti-p Decays
We observe a narrow enhancement near 2m{sub p} in the invariant mass spectrum of p{bar p} pairs from radiative J/{psi} {yields} {gamma}p{bar p} decays. No similar structure is seen in J/{psi} {yields} {pi}{sup 0} p{bar p} decays. The results are based on an analysis of a 58 million event sample of J/{psi} decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m{sup p} at M = 1859{sub -10}{sup +3} (stat){sub -25}{sup +5} (sys) MeV/c{sup 2} and the total width is {Lambda} < 30 MeV/c{sup 2} at the 90 percent confidence level. These mass and width values are not consistent with the properties of any known particle.