42021497
Statistics of anyon gas and the factorizable property of thermodynamic quantities.
The statistical distribution function of anyon is used to find the eighth viral coefficient in the high-temperature limit and the equation of state in the low-temperature limit. The perturbative results indicate that the thermodynamic quantities, $Q(\alpha)$, of the free anyon gas may be factorized in the terms characteristic of the ideal Bose ($\alpha =0$) and fermion ($\alpha =1$) gases, i.e., $Q(\alpha) = \alpha Q(1) + (1-\alpha) Q(0)$. It is shown that the factorizable property of the thermodynamic quantities, to all orders, can be established from the property of the equivalence between the anyon statistics and statistics in a system with boson-fermion transmutation, which was found by us in a recent paper (hep-th/0308095; Phys. Rev. E 51 (1995) 3729)
13332555
Thermodynamics on noncommutative geometry in coherent state formalism
Abstract The thermodynamics of ideal gas on the noncommutative geometry in the coherent state formalism is investigated. We first evaluate the statistical interparticle potential and see that there are residual “attraction (repulsion) potential” between boson (fermion) in the high temperature limit. The characters could be traced to the fact that, the particle with mass m in noncommutative thermal geometry with noncommutativity θ and temperature T will correspond to that in the commutative background with temperature T ( 1 + k T m θ ) −1 . Such a correspondence implies that the ideal gas energy will asymptotically approach to a finite limiting value as that on commutative geometry at T θ = ( k m θ ) −1 . We also investigate the squeezed coherent states and see that they could have arbitrary mean energy. The thermal properties of those systems are calculated and compared to each other. We find that the heat capacity of the squeezed coherent states of boson and fermion on the noncommutative geometry have different values, contrast to that on the commutative geometry.
119556809
Quantum stabilization of compact space by extra fuzzy space
We investigate the quantized scalar field on the Kaluza–Klein spacetimes of MD×Td×SFZ, where MD is the ordinary D-dimensional flat Minkowski spacetimes, Td is the d-dimensional commutative torus, and SFZ is a noncommutative fuzzy two-sphere with a fixed quantized radius. After evaluating the one-loop correction to the spectrum we use the mass-corrected term to compute the Casimir energy of the scalar field on the model spacetime. It is seen that, for some values of D and d, the Casimir energy due to vacuum fluctuation in the model spacetimes could give rise a repulsive force to stabilize the commutative torus.
120467733
No-go theorem of the infrared divergences generated by cosmological evolution
Abstract It is proved that in curved spacetime the infrared divergences of a free field theory cannot arise through dynamical evolution from a state which is initially free of them.
46429286
Adiabatic regularization of the quantum stress-energy tensor in curved spacetimes: Path-integral quantization method.
A possible way to obtain the adiabatic regularized quantum stress-energy tensor in a background curved spacetime is developed within the method of path-integral quantization. As an illustration, we study the mode of a massive scalar field with arbitrary curvature coupling to the inhomogeneous conformally flat spacetime. The results so obtained are useful to investigate the back-reaction effects of a quantized field in the early Universe with an inhomogeneity.
3203139
Tubular Solutions in NS5-brane, Dp-brane and Macroscopic Strings Backgrounds
We present our searches for the tubular bound states of a D2-brane with m D0-branes and n fundamental strings in the NS5-brane, Dp-brane or macroscopic strings background by solving the Dirac-Born-Infeld equation. The geometry of tubular configurations we considered are taken to be parallel to the background branes or macroscopic strings. The n fundamental strings therein may be the circular strings Fc or the straight strings Fs, which are along the cross section or the axis of the tube respectively. We show that the stable tubular bound states of (nFs, mD0, D2) which are prevented form collapse by the angular momentum, as original found in flat space, could be formed in the NS5-brane, D6-brane and macroscopic strings background. However, they becomes unstable in the D2-brane and D4-brane background. We also show that there are stable tubular bound states of (nFc, mD0, D2) and (mD0, D2), which are prevented form collapse by the gravitational forces in the backgrounds of D6-brane. We discuss the properties of these tubular solutions and see that only that in the macroscopic strings background is a supersymmetric BPS configuration.
29696360
Nonperturbative effects on the Wilson coefficients and the Delta I=(1/2 rule in kaon decays.
We apply the vacuum-background-field method and the modified renormalization-group equation in the energy region {mu}{lt}1 GeV to correct the Wilson coefficients in the {Delta}{ital S}=1 effective weak Hamiltonian responsible for {ital K}{r arrow}2{pi} decays. We find that the change of {ital C}{sub {plus minus}} results in an enhancement to the {Delta}{ital I}={1/2} amplitude by a factor of 2 at the scale {mu}=0.6 GeV for {ital K}{r arrow}2{pi} decays.
35673041
Decays of excited charmed Lambda -type and Sigma -type baryons in heavy hadron chiral perturbation theory.
Ground states and some excited p-wave states of heavy baryons are studied within the framework of heavy hadron chiral perturbation theory. The effective Lagrangian is written out to terms of the next-to-leading order in 1/${\mathit{m}}_{\mathit{Q}}$ or 1/${\mathrm{\ensuremath{\Lambda}}}_{\mathrm{\ensuremath{\chi}}}$. The coupling constants are estimated using the experimental data of \ensuremath{\Lambda} and \ensuremath{\Sigma} baryons in the static limit of the s quark. The single pion and double pion decay rates of these charmed baryons have been estimated. The numerical results show that both ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}$(1/${2}^{\mathrm{\ensuremath{-}}}$) and ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}$(3/${2}^{\mathrm{\ensuremath{-}}}$) are very narrow. We conclude that the two pion channel may offer the best hope for detecting the ${\mathrm{\ensuremath{\Sigma}}}_{\mathit{c}}$(3/${2}^{\mathrm{\ensuremath{-}}}$) and ${\mathrm{\ensuremath{\Sigma}}}_{\mathit{c}}$(1/${2}^{\mathrm{\ensuremath{-}}}$) p-wave doublet.
7506859
Light quark dependence of the Isgur-Wise function from QCD sum rules.
We study the light quark dependence of the Isgur-Wise function for ${\mathit{B}}_{\mathit{a}}$\ensuremath{\rightarrow}${\mathit{D}}_{\mathit{a}}$ and ${\mathit{B}}_{\mathit{a}}$\ensuremath{\rightarrow}${\mathit{D}}_{\mathit{a}}^{\mathrm{*}}$ in the framework of QCD sum rules. At zero recoil all the Isgur-Wise functions are equal, as required by heavy quark symmetry, and at nonzero recoil the Isgur-Wise function for ${\mathit{B}}_{\mathit{s}}$ decay falls faster than that for ${\mathit{B}}_{\mathit{u},}$d decay, which is just contrary to the recent prediction of the heavy meson chiral perturbation theory. As a by-product we also estimate SU(3)-breaking effects in the mass and the decay constant.
11192776
Preservation of proton polarization by a partial Siberian snake.
A 9[degree] solenoidal spin rotator or 5% partial Siberian Snake was used to successfully accelerate polarized protons for the first time to 10.8 GeV kinetic energy in the Brookhaven Alternating Gradient Synchrotron with partial depolarization due to the intrinsic resonance crossing. It was found that a 5% partial snake can effectively overcome 18 imperfection resonances in this energy range. We also observed an interference between the spin flip induced by an intrinsic resonance and linear coupling due to the solenoid field of the partial snake.
73519332
RHIC Performance for FY10 200 GeV Au+Au Heavy Ion Run
Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of = 12 × 10 cm−2 s−1 by operating with 103 bunches (out of 111 possible), and by squeezing to β∗ = 0.85 m. This year, Run-10, we achieved = 20 × 10 cm−2 s−1, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased β∗ to 0.75 m, operated with 111 bunches per ring, and reduced longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance.