241 research outputs found
Mirror effect induced by the dilaton field on the Hawking radiation
We discuss the string creation in the near-extremal NS1 black string
solution. The string creation is described by an effective field equation
derived from a fundamental string action coupled to the dilaton field in a
conformally invariant manner. In the non-critical string model the dilaton
field causes a timelike mirror surface outside the horizon when the size of the
black string is comparable to the Planck scale. Since the fundamental strings
are reflected by the mirror surface, the negative energy flux does not
propagate across the surface. This means that the evaporation stops just before
the naked singularity of the extremal black string appears even though the
surface gravity is non-zero in the extremal limit.Comment: 15 page
Measurement of the tensor analyzing power T20 in the dd->^3Hen and dd->^3Hp at intermediate energies and at zero degree
The data on the tensor analyzing power T20 in the dd->^3Hen and dd-> ^3Hp
reactions at 140, 200 and 270 MeV of the deuteron kinetic energy and at zero
degree obtained at RIKEN Accelerator Research Facility are presented. The
observed positive sign of T20 clearly demonstrates the sensitivity to the D/S
wave ratios in the ^3He and ^3H in the energy domain of the measurements. The
T20 data for the ^3He-n and ^3H-p channels are in agreement within experimental
accuracy.Comment: 9 pages, 3 figures, submitted in Phys.Lett.
Three-body dN interaction in the analysis of the 12C(pol_d,d') reaction at 270 MeV
We have measured the cross sections and analyzing powers Ay and Ayy for the
elastic and inelastic scattering of deuterons from the 0+(g.s.), 2+(4.44 MeV),
3-(9.64 MeV), 1+(12.71 MeV), and 2-(18.3 MeV) states in 12C at an incident
energy of 270 MeV. The data are compared with microscopic distorted-wave
impulse approximation calculations where the projectile-nucleon effective
interactionis taken from the three-nucleon t-matrix given by rigorous Faddeev
calculations presently available at intermediate energies. The agreement
between theory and data compares well with that for the (p,p') reactions at
comparable incident energies/nucleon.Comment: 17 pages, 3 Postscript figure
Analyzing powers Ayy, Axx, Axz and Ay in the dd->3Hen reaction at 270 MeV
The data on the tensor Ayy, Axx, Axz and vector Ay analyzing powers in the
dd->3Hen obtained at Td= 270 MeV in the angular range 0 - 110 degrees in the
c.m. are presented. The observed negative sign of the tensor analyzing powers
Ayy, Axx and Axz at small angles clearly demonstrate the sensitivity to the
ratio of the D and S wave component of the 3He wave function. However, the
one-nucleon exchange calculations by using the standard 3He wave functions have
failed to reproduce the strong variation of the tensor analyzing powers as a
function of the angle in the c.m.Comment: 8 pages, 7 figures, 4 tables. Submitted to EPJ
Analyzing power for the proton elastic scattering from neutron-rich 6He nucleus
Vector analyzing power for the proton-6He elastic scattering at 71
MeV/nucleon has been measured for the first time, with a newly developed
polarized proton solid target working at low magnetic field of 0.09 T. The
results are found to be incompatible with a t-matrix folding model prediction.
Comparisons of the data with g-matrix folding analyses clearly show that the
vector analyzing power is sensitive to the nuclear structure model used in the
reaction analysis. The alpha-core distribution in 6He is suggested to be a
possible key to understand the nuclear structure sensitivity.Comment: 5 pages, 3 figures, accepted for publication as a Rapid Communication
in Physical Review
Precise Measurement of dp Elastic Scattering at 270 MeV and Three-Nucleon Force Effects
The cross section, the deuteron vector Ayd and tensor analyzing powers Aij, the polarization transfer coefficients Kijy′, and the induced polarization Py′ were measured for the dp elastic scattering at 270 MeV. The cross section and Ayd are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, Aij, Kijy′, or Py′ are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models
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