119972193
Measurements of total reaction cross sections for some light nuclei at intermediate energies
Measurements of the total reaction cross section for C12-16, N14-17, and O16-18 on carbon target at intermediate energies were performed on the Radioactive Ion Beam Line of the Heavy ion Research Facility in Lanzhou. A larger enhancement of sigma(R) for C-15 was observed than for its neighbors. Evidence for possible anomalous nuclear structure in C-15 was revealed in the analysis of the total reaction cross section in terms of the difference factor d.
123463436
Isospin Effect of Fragmentation Reaction on the Isotopic Distribution Produced in Intermediate Energy Heavy Ion Collisions
Fragments produced in the reaction of 60MeV/n O-18 On Be have been measured experimentally. The isotopic distribution of fragmentation reaction is well reproduced by a modified statistical abrasion-ablation model. It is predicted that the isotopic distribution shifts toward the neutron rich side for neutron rich projectile, but this isospin effect decreases with the increase of the atomic number difference Z - Z(A) and disappears at last, where Z and Z(A) are atomic numbers of the isotopic distribution and the projectile respectively.
53131397
Energy and system-size dependence of two- and four-particle $v_2$ measurements in heavy-ion collisions at RHIC and their implications on flow fluctuations and nonflow
We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants $v_2$ ($v_2\{2\}$ and $v_2\{4\}$) for Au+Au and Cu+Cu collisions at center of mass energies $\sqrt{s_{_{\mathrm{NN}}}} = 62.4$ and 200 GeV. The difference between $v_2\{2\}^2$ and $v_2\{4\}^2$ is related to $v_{2}$ fluctuations ($\sigma_{v_2}$) and nonflow $(\delta_{2})$. We present an upper limit to $\sigma_{v_2}/v_{2}$. Following the assumption that eccentricity fluctuations $\sigma_{\epsilon}$ dominate $v_2$ fluctuations $\frac{\sigma_{v_2}}{v_2} \approx \frac{\sigma_{\epsilon}}{\epsilon}$ we deduce the nonflow implied for several models of eccentricity fluctuations that would be required for consistency with $v_2\{2\}$ and $v_2\{4\}$. We also present results on the ratio of $v_2$ to eccentricity.
123856190
Existence of a proton halo in Al-23 and its significance
Reaction cross section sigma(R) of proton-rich isotones (N = 10) near Al-23 and Al isotopes (Al23-28) on C target have been measured at intermediate energies around 30 MeV/nucleon. An abnormal increase of the experimental sigma(R) is observed for Al-23 and it suggests that there is an anomalously large matter rms radius in Al-23. Together with the very weakly binding of the last proton (S-p = 0.125 MeV), it indicates that there is a proton halo in Al-23. This conclusion is also supported by the difference factor d which is deduced from the measured and theoretical sigma(R) in the Glauber or Boltzmann-Uehling-Uhlenbeck model and is used for the manifest of halo phenomena. The theoretical calculation based,on the relativistic density dependent Hartree model shows that there is a proton halo when the last proton is in the 2s(1/2) orbit in Al-23. The significance of the proton halo in Al-23 is discussed.
119257780
Model independent analysis of top quark forward-backward asymmetry at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$
We present the complete calculations of the forward-backward asymmetry ($A_{\rm FB}$) and the total cross section of top quark pair production induced by dimension-six four quark operators at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$. Our results show that next-to-leading order (NLO) QCD corrections can change $A_{\rm FB}$ and the total cross section by about 10%. Moreover, NLO QCD corrections reduce the dependence of $A_{\rm FB}$ and total cross section on the renormalization and factorization scales significantly. We also evaluate the total cross section and the charge asymmetry ($A_{\rm C}$) induced by these operators at the Large Hadron Collider (LHC) up to $\mathcal{O}(\as^2/\Lambda^2)$, for the parameter space allowed by the Tevatron data. We find that the value of $A_{\rm C}$ induced by these operators is much larger than SM prediction, and LHC has potential to discover these NP effects when the measurement precision increases.
55233481
The Dipole Wakefield for a Rounded Damped Detuned Linear Accelerator with Optimised Cell-to-Manifold Coupling
A redesign of the basic cell configuration of the Damped Detuned Structure has been briefly reported where the cells are referred to as ellipsoidal cavities, and accelerator structures incorporating them are designated DDS5 and DDS6. This new structure type has been renamed RDDS 1, and the first of this series, RDDS 1, is presently under design and fabrication. The carefully sculpted cell profile (fabricated on computer controlled lathes at KEK incorporating diamond point machining) provides a 20% increase in shunt impedance which, when combined with other parameters, allows for a dramatic reduction in the RF power required for the NLC (Next Linear Collider). The detuning profile, damping manifold taper, and the cell to manifold coupling constant profile have all been carefully optimized so as to permit decoupling the cells at the ends of the structure from the manifolds while still adequately minimizing the transverse wake. The decoupling is required in order to fit adequately matched terminations into the structure. The single structure analysis has been supplemented with studies of wake degradation arising from systematic fabrication errors and wake improvement obtained by combining manifold damping with structure interleaving.
11103428
The Broad Fe K-Line Profile in NGC 4151
We present an analysis of the Fe K-line profile of NGC 4151 by using long ASCA observation data obtained in 1995 May. The unprecedented good data quality, which is much better in the energy band around 6.4 keV than that of the famous 4.2 day ASCA observation of MCG -6-30-15 in 1994 July, offers a unique opportunity to study the details of Fe K-line profile. Apart from those characteristics already noticed in earlier ASCA observations on this object (Yaqoob et al.; a broad and skewed profile with a strong peak at about 6.4 keV and a large red wing extending to ~4-5 keV), which is remarkably similar to that of MCG -6-30-15, we also find a weak blue wing extending to about 8 keV, thanks to the good quality of the data. When fitted by a relativistic accretion disk line plus a narrow core at 6.4 keV, the data constrain the accretion disk to be nearly face-on, contrary to the edge-on geometry inferred from optical and UV observations. However, the extended blue wing can not be well fitted even after we include corresponding Fe Kβ components. Ni Kα-line emission by an amount of 12% of Fe Kα is statistically required. An alternative explanation is a model consisting of a narrow core and two disk lines with inclinations of 58° and 0°, respectively. We suppose that the component with inclination of 58° was observed directly, consistent with its edge-on geometry, and the component with inclination of 0° was scattered into our line of sight by a Compton mirror, which might be the cool accretion disk corona proposed by Poutanen et al.
118444339
Threshold resummation effects in Higgs boson pair production at the LHC
A bstractWe investigate the resummation effects in the Standard Model Higgs boson pair production through gluon-gluon fusion at the LHC with soft-collinear effective theory. We calculate the total cross section and the invariant mass distribution at Next-to-Next-to-Leading-Logarithmic level with π2-enhanced terms resummed, which are matched to the QCD Next-to-Leading Order results. In the high order QCD predictions exact top quark mass effects are included in full form factors. Our results show that the resummation effects increase the Next-to-Leading Order results by about 20% ~ 30%, and the scale uncertainty is reduced to 8%, which leads to increased confidence on the theoretical predictions. The PDF+αs uncertainties are almost not changed after including resummation effects. We also study the sensitivities of the total cross section and the invariant mass distribution to the Higgs boson self-coupling. We find that the total cross section and the invariant mass distribution shape depend strongly on the Higgs boson self-coupling, and therefore it is possible to extract Higgs boson self-coupling from the total cross section and invariant mass distribution when the measurement precision increases at the LHC.
119231982
A POSSIBLE ULTRA STRONG AND BROAD Fe Kα EMISSION LINE IN SEYFERT 2 GALAXY IRAS 00521-7054
We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A strong feature at {approx}6 keV (observer's frame) can be formally fitted with a strong (EW = 1.3 {+-} 0.3 keV in the rest frame) and broad Fe K{alpha} line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed power law (with {Gamma} = 1.8 {+-} 0.2 and N{sub H} 5.9{sup +0.6}{sub -0.7} Multiplication-Sign 10{sup 22} cm{sup -2}) plus a soft component. If due to relativistically smeared reflection by an X-ray illuminated accretion disk, the spin of the supermassive black hole (SMBH) is constrained to be 0.97{sup +0.03}{sub -0.13} (errors at 90% confidence level for one interesting parameter), and the accretion system is viewed at an inclination angle of 37 Degree-Sign {+-} 4 Degree-Sign . This would be the first type 2 active galactic nucleus reported with strong red Fe K{alpha} wing detected which demands a fast rotating SMBH. The unusually large EW would suggest that the light bending effect is strong in this source. Alternatively, the spectra could be fitted by a dual-absorber model (though with a global {chi}{sup 2} higher by {approx}6 for 283 dof) with N{sub H1} 7.0 {+-} 0.8more » Multiplication-Sign 10{sup 22} cm{sup -2} covering 100% of the X-ray source, and N{sub H2} = 21.7{sup +5.6}{sub -5.4} Multiplication-Sign 10{sup 22} cm{sup -2} covering 71%, which does not require an extra broad Fe K{alpha} line.« less