119073126
Improved approach to the heavy to light form-factors in the light cone QCD sum rules
A systematic analysis shows that the main uncertainties in the form factors are due to the twist-3 wave functions of the light mesons in the light-cone QCD sum rules. We propose an improved approach, in which the twist-3 wave functions do not make any contribution and therefore the possible pollution by them can be avoided, to reexamine B-->pi semileptonic form factors. Also, a comparison between previous results and our results from the light-cone QCD sum rules is made. Our method will be beneficial to the precise extraction of \V-ub\ from the experimental data on the processes B-->pil )over tilde>(l).
119164145
Heavy-to-light transition form factors and their relations in light-cone QCD sum rules
The light-cone QCD sum rules approach improved by using the chiral current correlator is systematically reviewed and applied to the calculation of all the heavy-to-light form factors, including all the semileptonic and penguin ones. By choosing suitable chiral currents, the light-cone sum rules for all the form factors are greatly simplified and depend mainly on one leading-twist distribution amplitude of the light meson. As a result, relations between these form factors arise naturally. At the considered accuracy, these relations reproduce the results obtained in the literature. Moreover, since the explicit dependence on the leading-twist distribution amplitudes is preserved, these relations may be more useful to simulate the experimental data and extract information on the distribution amplitude.
119652082
Unparticle physics and supersymmetry phenomenology
We show a natural form of the interaction between the unparticle and supersymmetry. Using the couplings of the unparticle to supersymmetry presented, as examples, we calculate the differential decay rates for the processes f-tilde{yields}f+U{sub 3/2}, {chi}-tilde{sup 0}{yields}{gamma}+U{sub 3/2}, {chi}-tilde{sup {+-}}{yields}W{sup {+-}}+U{sub 3/2} and {chi}-tilde{sup 0}{yields}Z{sup 0}+U{sub 3/2}. Finally, we discuss the phenomenological implication of our results and give some comments.
56465847
Effect of isospin-dependent cluster recognition on the observables in heavy ion collisions
We introduce isospin dependence in the cluster recognition algorithms used in the quantum molecular dynamics model to describe fragment formation in heavy ion collisions. This change reduces the yields of emitted nucleons and enhances the yields of fragments, especially heavier fragments. The enhancement of neutron-rich lighter fragments mainly occurs at midrapidity. Consequently, isospin-dependent observables, such as isotope distributions, yield ratios of n/p, t/ 3 He, and isoscaling parameters are affected. We also investigate how equilibration in heavy ion collisions is affected by this change.
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
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
119213488
Correlations in Horizontal Branch Oscillations and Break Components in XTE J1701-462 and GX 17+2
We studied the horizontal branch oscillations (HBO) and the band-limited components observed in the power spectra of the transient neutron star low-mass X-ray binary XTE J1701-462 and the persistent "Sco-like" Z source GX 17+2. These two components were studied based on the state-resolved spectra. We found that the frequencies of XTE J1701-462 lie on the known correlations (WK and PBK), showing consistency with other types of X-ray binaries (black holes, atoll sources, and millisecond X-ray pulsars). However, GX 17+2 is shifted from the WK correlation like other typical Z sources. We suggest that the WK/PBK main track forms a boundary that separates persistent sources from transient sources. The characteristic frequencies of break and HBO are independent of accretion rate in both sources, though it depends on spectral models. We also report the energy dependence of the HBO and break frequencies in XTE J1701-462 and how the temporal properties change with spectral state in XTE J1701-462 and GX 17+2. We studied the correlation between rms at the break and the HBO frequency. We suggest that HBO and break components for both sources probably arise from a similar physical mechanism: Comptonization emission from the corona. These two components could be caused by the same kind of oscillation in a corona with uneven density, and they could be generated from different areas of the corona. We further suggest that different proportions of the Comptonization component in the total flux cause the different distribution between GX 17+2 and XTE J1701-462 in the rmsbreak-rmsHBO diagram.