119197378
QCD resummation for light-particle jets
We construct an evolution equation for the invariant-mass distribution of light-quark and gluon jets in the framework of QCD resummation. The solution of the evolution equation exhibits a behavior consistent with Tevatron CDF data: the jet distribution vanishes in the small invariant-mass limit, and its peak moves toward the high invariant-mass region with the jet energy. We also construct an evolution equation for the energy profile of the light-quark and gluon jets in the similar framework. The solution shows that the energy accumulates faster within a light-quark jet cone than within a gluon jet cone. The jet energy profile convoluted with hard scattering and parton distribution functions matches well with the Tevatron CDF and the LHC CMS data. Moreover, comparison with the CDF and CMS data implies that jets with large (small) transverse momentum are mainly composed of the light-quark (gluon) jets. At last, we discuss the application of the above solutions for the light-particle jets to the identification of highly boosted heavy particles produced at the LHC. DOI: 10.1103/PhysRevD.87.074025
118596758
Uncertainty induced by QCD coupling in the CTEQ global analysis of parton distributions
We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strengths(MZ). We explain a simple method that is rigorously valid in the quadratic approximation normally applied in PDF fitting, and fully reproduces the correlated dependence of theoretical cross sections ons and PDF parameters. This method is based on a statistical relation that allows one to add the uncertainty produced bys, computed with some special PDF sets, in quadrature with the PDF uncertainty obtained for the fixeds value (such as the CTEQ6.6 PDF set). A series of four CTEQ6.6AS PDFs realizing this approach, fors values in the interval 0.116 � �s(MZ) � 0.120, is presented. Using these PDFs, the combineds and PDF uncertainty is assessed for theoretical predictions at the Fermilab Tevatron and Large Hadron Collider.
119114677
Progress in CTEQ-TEA PDF analysis
Recent developments in the CTEQ-TEA global QCD analysis are presented. The parton distribution functions CT10-NNLO are described, constructed by comparing data from many experiments to NNLO approximations of QCD. The global analysis of QCD makes use of experimental data from many short-distance scattering processes to construct, within some approximations, universal parton distribution functions (PDFs) for the proton. Then these functions can be used to calculate hadronic cross sections in the Standard Model and other theories. Global analysis and the resulting PDFs are necessary for the interpretation of experimental results at hadron colliders. Recently published PDFs are based on next-to-next-to-leading order (NNLO) approximations for perturbative QCD[1]. Complete calculations for this order of approximation are available for the running coupling s(Q), PDF evolution in Q, matrix elements in deep-inelastic scattering [2] and vector boson production [3]. The CTEQ analysis treats quark-mass eects in the S-ACOT- factorization scheme, which has been recently extended to two-loop, or NNLO, accuracy [4]. Though the NNLO matrix elements are still unknown for some important processes, such as the inclusive jet production in pp=pp collisions, it is important to use NNLO approximations, where available. CTEQ has developed PDFs for general-purpose computations and estimates of PDF-driven uncertainties over many years [5]. The most recent PDFs in this class, named CT10 and CT10W, were published in 2010 [6]. We now present a new family of CTEQ parton distributions, named CT10 NNLO. There are several reasons for publishing them. First, the CT10 NNLO global analysis is based on the NNLO approximation of perturbative QCD, whereas the CT10 and earlier analyses were based on NLO. Second, benchmarking of NLO jet cross sections [7]and DIS cross sections was performed to quantify theoretical uncertainties, and an in-depth study of the treatment of correlated experimental errors has been completed. Third, selection of experimental data sets has been revisited. The new NNLO PDFs are closely related to both CT10 and CT10W NLO PDFs and can be matched to either of two NLO PDF sets when comparing the NLO and NNLO cross sections. In all three cases, only data from pre-LHC experiments were used in the global fit. The same values of the QCD coupling and heavyquark masses as in CT10 NLO were assumed. Some results concerning CT10 NNLO PDFs
119246486
Probing the symmetry energy with isospin ratio from nucleons to fragments
Within the framework of ImQMD05, we study several isospin sensitive observables, such as DR(n/p) ratios, isospin transport ratio (isospin diffusion), yield ratios for LCPs between the projectile region and mid-rapidity region for the reaction systems Ni+Ni, Zn+Zn, Sn+Sn at low-intermediate energies. Our results show that those observables are sensitive to the density dependence of symmetry energy, and also depend on the cluster formation mechanism. By comparing these calculations to the data, the information of the symmetry energy and reaction mechanism is obtained.
119563640
Microscopic description of quantum shape fluctuation in C isotopes
Covariant density functional theory is used to investigate quantum shape fluctuation in {sup 16}C and other even-even carbon isotopes. Long-range correlations beyond the mean-field approximation are taken into account by configuration mixing of wave functions with triaxial shapes and by restoring the spontaneously broken rotational symmetry through a three-dimensional angular-momentum projection. The systematics of the excitation energy of the 2{sub 1}{sup +} state and the B(E2:2{sub 1}{sup +}{yields}0{sub 1}{sup +}) values in carbon isotopes are reproduced rather well. Decoupled structures with rather different deformations for neutrons and protons have been found in {sup 16,18,20}C. In addition, the effects of shape fluctuations in {beta} and {gamma} deformations on the low-lying excited states of these nuclei are examined.
119112933
Competition between Coulomb and symmetry potential in semi-peripheral heavy ion collisions
The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved Quantum Molecular Dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of Y(n)/Y(p). This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.
14803102
Strong couplings of heavy mesons to a light vector meson in QCD
We make a detailed analysis of the $BB\rho(DD\rho)$ and $B^*B\rho(D^{*}D\rho)$ strong couplings $g_{BB\rho}(g_{DD\rho})$ and $g_{B^*B\rho}(g_{D^{*}D\rho})$ using QCD light cone sum rules(LCSR). The existing some negligence is pointed out in the previous LCSR calculation on $g_{B^*B\rho} (g_{D^{\ast}D\rho}$) and an updated estimate is presented. Our findings can be used to understand the behavior of the $B,D \to \rho$ semileptonic form factors at large momentum transitions.
119430774
A study of correlation between the oscillation amplitude and stellar parameters of delta Scuti stars in open clusters - Toward selection rules for delta Scuti star oscillations
In the present work, we study correlations between stellar fundamental parameters and the oscillation amplitude for Scuti stars. We present this study for a sample of 17 selected Scuti stars belonging to 5 young open clusters. Taking advantage of properties of Scuti stars in clusters, we correct the photometric parameters of our objects for the eects of fast rotation. We confirm the benefit of applying such corrections in this kind of studies. In addition, the technique used for this correction allows us to obtain an estimate of stellar parameters such as the angle of inclination and the rotation rate, usually not accessible. A significant correlation between the parameter i 0 (estimation of the angle of inclination of the star) and the oscillation amplitude is found. A discussion and interpretation of these a priori surprising results is proposed, in terms of a possible selection rule for oscillation modes of Scuti stars.