118623641
Threshold resummation effects in neutral Higgs boson production by bottom quark fusion at the CERN Large Hadron Collider
We investigate the QCD effects in the production of neutral Higgs bosons via bottom quark fusion in both the standard model and the minimal supersymmetric standard model at the CERN Large Hadron Collider. We include the next-to-leading order (NLO) QCD corrections (including supersymmetric QCD) and the threshold resummation effects. We use the soft-collinear effective theory to resum the large logarithms near threshold from soft gluon emission. Our results show that the resummation effects can enhance the total cross sections by about 5% compared with the NLO results.
120148837
CT10 next-to-next-to-leading order global analysis of QCD
We present next-to-next-to-leading order (NNLO) parton distribution functions (PDFs) from the CTEQ-TEA group. The CT10NNLO PDF fit is based on essentially the same global data sets used in the CT10 and CT10W NLO PDF analyses. After exploring the goodness of the fits to the HERA combined data and the Tevatron jet data, we present various predictions at NNLO accuracy for both existing and forthcoming precision measurements from the CERN Large Hadron Collider. The range of variations in the gluon distribution introduced by correlated systematic effects in inclusive jet production is also examined.
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
118596197
Discriminating Higgs production mechanisms using jet energy profiles
We present a new tool for precision measurements of the Higgs boson production mechanisms at the LHC. We study events with a Higgs boson produced with two forward jets. Even with fairly stringent cuts, one expects a significant contamination of gluon fusion (GF) in addition to vector-boson fusion (VBF) in the event sample. By measuring the jet energy profile of the most central jet, we find that SM production can be distinguished from either pure VBF or pure GF at the 5 sigma level with 100 fb(-1) of luminosity at the 14 TeV LHC. Moreover, this discrimination technique can be used to validate or rule out new physics models that predict similar observable branching fractions as the 125 GeV Standard Model Higgs boson but have different production mechanisms.
119264529
Next-to-leading order QCD effects in associated charged Higgs and W boson production in the MSSM at the CERN Large Hadron Collider
We present the calculations of the next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the associated production of the ${W}^{\ifmmode\pm\else\textpm\fi{}}{H}^{\ensuremath{\mp}}$ through $b\overline{b}$ annihilation in the minimal supersymmetric standard model at the CERN Large Hadron Collider. The NLO QCD corrections can either enhance or reduce the total cross sections, but they generally efficiently reduce the dependence of the total cross sections on the renormalization/factorization scale. The magnitude of the NLO QCD corrections is about 10% in most of the parameter space and can reach 15% in some parameter regions. We also show the Monte Carlo simulation results for the $2j+{\ensuremath{\tau}}_{\mathrm{jet}}+{\mathrm{p\ensuremath{\llap{\not\;}}}}_{T}$ signature from the ${W}^{\ifmmode\pm\else\textpm\fi{}}$ and the ${H}^{\ensuremath{\mp}}$ decays including the NLO QCD effects, and find an observable signal at a $5\ensuremath{\sigma}$ level in some parameter region of the minimal supergravity model.
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
18265717
The Isospin Splittings of Heavy-Light Quark Systems
The mass splittings of the pseudoscalar and vector D and B light-heavy quark systems have been calculated using the method of QCD sum rules. Electromagnetic, quark mass, and nonperturbative QCD effects are all included. The results are in good agreement with experiment. A measurement of isospin splitting for the vector B mesons would give valuable information about quark mass splittings.
119919283
Medium effects on the double Delta production and absorption cross-section
The explicit expressions for calculating the in-medium N+N{r_arrow}{Delta}+{Delta} and {Delta}+{Delta}{r_arrow}N+N cross section have been derived within the framework of the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck approach in which the deltas and nucleons are treated on an equal footing. The obtained cross sections are consistent with the other integrands of the transport model. The theoretical prediction of the free double-{Delta} production cross section is in good agreement with the experimental data. All the medium effects on the double-{Delta} production and absorption cross section are studied systematically, and strong medium corrections are found. Our numerical results show that it would be important to take the N+N{r_arrow}{Delta}+{Delta} and {Delta}+{Delta}{r_arrow}N+N channel into account in the study of relativistic heavy-ion collisions at intermediate and high energies. {copyright} {ital 1997} {ital The American Physical Society}
67842056
Beyond the relativistic mean-field approximation. III. Collective Hamiltonian in five dimensions
The framework of relativistic energy density functionals is extended to include correlations related to the restoration of broken symmetries and fluctuations of collective variables. A new implementation is developed for the solution of the eigenvalue problem of a five-dimensional collective Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The model is tested in a series of illustrative calculations of potential energy surfaces and the resulting collective excitation spectra and transition probabilities of the chain of even-even gadolinium isotopes.
126298053
Soft nonfactorizable contribution to anti-B0 ---> D0 pi0
118014681
Towards a Self-Consistent Description of the Relativistic Boltzmann-Uehling-Uhlenbeck Approach
The heavy ion collisions (HIC) provide a unique opportunity to study the time evolution process of nuclear matter under violent collisions as well as nuclear properties under extreme conditions of high density and temperature. However, the interesting informations on these problems can only be obtained indirectly through certain theoretical models. Thus, one has to choose a good theoretical tool, which should be as general and basic as possible on the one hand and as practicable as possible on the other hand. The most ambitious one is to obtain the relativistic transport equation starting from the time dependent Bruckner G-matrix theory1. In this approach the time evolution of the HIC process is described by relativistic kinetic equation and the G-matrix served as a dynamical input of the two body interaction. Therefore, to acquire complete numerical solution will be very difficult and till now there has no real calculation which fulfills this requirement.