arXiv subjects

K. Tanaka

Publications and source records attributed to K. Tanaka.

186 records · Page 11Linked to original sources

arXiv1997

A New Limit on the Flux of Cosmic Antihelium

A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1) at the top of the atmosphere in the rigidity region 1 to 16 GV, after correcting for the estimated interaction loss of antihelium in the air and in the instrument. The corresponding upper limit on the Hebar/He flux ratio is 3.1*10**(-6), 30 times more stringent than the limits obtained in similar rigidity regions with magnetic spectrometers previous to BESS.

astro-ph↗

arXiv1997

Mesons in 2-Dimensional QCD on the Light Cone

Two dimensional QCD is quantized on the light front coordinate. We solve the Einstein-Schrödinger equation by the use of Tamm-Dancoff truncation and find that the simplest wavefunction produces the $M/g$ versus $m/g$ relation in agreement with other calculations, where $M$ and $m$ are the masses of the ground state and quarks, respectively.

hep-th↗

arXiv1997

Q^2 Evolution of Chiral-Odd Twist-3 Distributions h_L(x, Q^2) and e(x, Q^2) in Large-N_c QCD

We prove that the twist-3 chiral-odd parton distributions obey simple Gribov-Lipatov-Altarelli-Parisi evolution equations in the limit $N_c\to\infty$ and give analytic results for the corresponding anomalous dimensions. To this end we introduce an evolution equation for the corresponding three-particle twist-3 parton correlation functions and find an exact analytic solution. For large values of n (operator dimension) we are further able to collect all corrections subleading in N_c, so our final results are valid to $O(1/N_c^2\cdot \ln(n)/n)$ accuracy.

hep-ph↗

arXiv1996

Q^2-evolution of chiral-odd twist-3 distributions h_L(x,Q^2) and e(x, Q^2) in the large N_c limit

We prove that the twist-3 chiral-odd parton distributions obey simple GLAP evolution equations in the limit $N_c\to\infty$ and give analytic formulae for the corresponding anomalous dimensions. The results are valid to O(1/N_{c}^2) accuracy and will be useful in confronting with future experiments.

hep-ph↗

arXiv1995

Fermionic excitation in quark matter

We discuss the fermionic excitation spectra of the dense QCD and QED plasma at zero temperature, and analyze the stability of the normal (perturbative) ground state. The standard re-summed perturbation theory breaks down because the infrared (IR) divergences show up in the spectra near the Fermi surface. We employ the effective field theory approach and the renormalization group to investigate the dynamics near the Fermi surface. Our results indicate that the dense QCD and QED plasma are non-Fermi-liquids.

hep-ph↗

arXiv1994

Q^2-Evolution of Nucleon's Chiral-Odd Twist-3 Structure Function: h_L(x,Q^2)

We investigate the $Q^{2}$-evolution of the chiral-odd spin-dependent parton distribution $h_{L}(x, Q^{2})$ relevant for the polarized Drell-Yan processes. The results are obtained in the leading logarithmic order in the framework of the renormalization group and the standard QCD perturbation theory. We calculate the anomalous dimension matrix for the twist-3 operators for $h_{L}$ in the one-loop order. The operator mixing among the relevant twist-3 operators including the operators proportional to the QCD equations of motion is treated properly in a consistent scheme. Implications for future experiments are also discussed.

hep-ph↗