32063766
Next-to-leading-order QCD corrections to e+e- -->J/psi gg at the B factories.
We calculate the next-to-leading-order (NLO) QCD corrections to e;{+}e;{-}-->J/psi gg via color singlet J/psi(3S1) at the B factories. The result shows that the cross section is enhanced to 0.373 pb by a K factor (NLO/LO) of about 1.21. By considering its dependence on the charm quark mass and renormalization scale, the NLO cross section can range from 0.294 to 0.409 pb. Further including the psi;{'} feed-down, sigma[e;{+}e;{-}-->J/psi X(non-cc[over ])] is enhanced by another factor of about 1.29 and reach 0.482 pb. In addition, the momentum distributions of J/psi production and polarization are presented. Recent measurements from Belle agree well with our prediction for the cross section and momentum distribution. It is expected that this process can serve as a very good channel to clarify the J/psi polarization puzzle by performing further experimental measurements.
118291411
Next-to-Leading-Order QCD corrections to $J/\psi (\upsilon) + \gamma$ production at the LHC
In this work, we calculate the next-to-leading-order (NLO) QCD corrections to the process $p+p \to J/\psi + \gamma$ via the color-singlet mechanism at the LHC. The results show that the partial cross section ($p_t^{J/\psi}>$3GeV and $|y^{J/\psi,\gamma}|<$3) is enhanced by a factor of about 2.0, and the differential cross section can be enhanced by two orders of magnitude in the large transverse momentum region of $J/\psi$. Furthermore, the polarization of $J/\psi$ changes from transverse polarization at leading-order to longitudinal polarization at NLO. For the inclusive $J/\psi$ hadroproduction, it is known that the color-octet contributions are one order of magnitude larger than the color-singlet contribution, and the polarization distribution is dominated by the color-octet behavior at NLO. In contrast, for $J/\psi+\gamma$ production the color-singlet contribution is of the same order as the color-octet contribution, and the polarization distribution arises from both the color-singlet and color-octet. Therefore, measurements of $J/\psi$ production associated with a direct photon at the hadron collider could be an important supplement to testify the theoretical framework treating with the heavy quarkonium. In addition, an NLO QCD correction to $\Upsilon+\gamma$ production at the LHC is also presented in this paper.
123418843
The realizations of quantum groups of An−1 and Cn types in q-deformed oscillator systems at classical and quantum levels
In the classical q‐deformed oscillators system, the Poisson bracket realizations of the quantum enveloping algebras of An−1 and Cn types are given in the symplectic space (V,Ω) (without deformation). When the oscillators system is canonically quantized, the Lie bracket realizations of the quantum enveloping algebras of An−1 and Cn types are obtained. The Hopf structures of these quantum enveloping algebras are supplied.
122372922
A GENERAL-METHOD FOR CALCULATING PRINCIPAL VALUE INTEGRALS NUMERICALLY IN AN N-DIMENSIONAL REGION
Abstract Based on the antithetic cancellation technique, we propose a numerical method to calculate the N -dimensional principal value integrals. This method is powerful for numerically evaluating a multi-dimensional Feynman parameter integral with the singularity which occurs in loop calculations of quantum field theories, when some internal lines of the related Feynman diagrams are allowed by kinematics to approach to the corresponding mass shells.
123412047
UNIVERSALLY TREATING THE QUARK PAIR WITH A VACUUM QUANTUM NUMBER IN THE RELATED CHARM DECAYS
A method for universally treating the quark pair with a vacuum quantum number is proposed and it is applied to calculating some charm meson decays as examples. The smallness for W-exchange and annihilation mechanisms has new explanation and the result obtained by means of the proposed method on the decay fits the experimental data well.
119071655
The $J/\psi$ production associated with a hard photon and the color octet signature in $e^{+} e^{-}$ annihilation
$J/\ensuremath{\psi}$ production associated with a hard photon in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation, being of a QED nature, is investigated thoroughly in this paper. To show its influence on the observation of the color-octet signature in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation via $J/\ensuremath{\psi}$ inclusive production, the cross sections of $J/\ensuremath{\psi}$ production through different mechanisms at various energies are compared quantitatively by presenting them in figures together. The contribution from the production associated with a hard photon to the inclusive production of $J/\ensuremath{\psi}$ is pointed out to be significant at the concerned energies; thus, the influence of it on the observation of the color-octet signature should be dealt with carefully.
118674100
J/ψ production via photon fragmentation at hadron colliders
The transverse momentum (p(t)) distributions of production and polarization for J/psi measured by CDF Collaboration are still challenging our understanding of the heavy quarkonium production mechanism even with recent significant theoretical progresses on the next-to-leading-order (NLO) QCD calculation. We investigate an interesting mechanism for J/psi production at hadron collider, pp((p) over bar) -> gamma* (J/psi) + X with J/psi from a virtual photon gamma* fragmentation. Our calculations show that the J/psi p(t) distribution in the photon fragmentation process up to NLO in alpha(s) will be larger than that of the conventional J/psi production from the color-singlet mechanism at NLO when p(t) > 26 (35) GeV at the Tevatron (LHC) and reach about 6 (10) times of the conventional one when p(t) = 50 (100) GeV at the Tevatron (LHC), in spite of a suppression factor (alpha/alpha(s))(2) that is associated with the QED and QCD coupling constants. In addition, it also has large impact on the p(t) distribution of J/psi polarization in large p(t) region. Therefore, it is an important mechanism for J/psi production at large p(t) region especially for the LHC. (c) 2012 Elsevier B.V. All rights reserved.
118350998
Next-to-leading order QCD predictions for graviton and photon associated production in the Large Extra Dimensions model at the LHC
We present the calculations of the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein (KK) graviton and photon associated production process pp{yields}{gamma}G{sub KK}+X in the large extra dimensions model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution, and the pseudorapidity distribution of photon.
122925118
Monte Carlo simulation of the response of Si(Li) detectors to monoenergetic X-rays
Abstract We present a Monte Carlo simulation of X-ray interaction with a Si(Li) detector which includes for the first time both a detailed description of the atomic excitation and de-excitation and also a physically realistic model of the frontal region of incomplete charge collection. Simulated lineshapes are in good agreement with those measured by us using monoenergetic X-rays of energy 1–10 keV and by varying the two parameters of the model we can generate lineshapes very similar to those reported in the literature for other Si(Li) detectors.
17925572
Feedback limits rapid growth of seed black holes at high redshift
Seed black holes formed in the collapse of Population III stars have been invoked to explain the presence of supermassive black holes at high redshift. It has been suggested that a seed black hole can grow up to through highly super-Eddington accretion for a period of similar to 10(6)-10(7) at redshift. We studied the feedback of radiation pressure, Compton heating, and outflow during the seed black hole growth. It is found that its surrounding medium fueled to the seed hole is greatly heated by Compton heating. For a supercritical accretion onto a seed hole, a Compton sphere ( with a temperature similar to 10(6) K) will be formed 10(3) M-circle dot on a timescale of 1.6 x 10(3) yr so that the hole is only supplied by a rate of 10(-3) of the Eddington the Compton sphere. The kinetic feedback of the strong outflow will heat the medium at a large distance from the black hole; this leads to a dramatic decrease of the outer Bondi accretion onto the black hole and avoids the accumulation of the matter. The highly supercritical accretion will be rapidly halted by the strong feedback. The seed black hole hardly grows up at the very early universe unless the strong feedback can be avoided.
125503501
Measurement of branching fractions for two-body B meson decays with charmonium at Belle