As an addendum to our previous evaluation of the weak-interaction corrections to hadronic top-quark pair production we determine the leading weak-interaction contributions due to the subprocesses $b {\bar b} \to t {\bar t}$ and $g q ({\bar q}) \to t {\bar t} q ({\bar q})$. For several distributions in $t {\bar t}$ production at the LHC we find that these contributions are non-negligible as compared to the weak corrections from the other partonic subprocesses.
The inclusive hadronic production of $η_Q$($η_c$ or $η_b$) pair is proposed to extract the transverse momentum dependent(TMD) gluon distribution functions. We use nonrelativistic QCD(NRQCD) for the production of $η_Q$. Under nonrelativistic limit TMD factorization for this process is assumed to make a lowest order calculation. For unpolarized initial hadrons, unpolarized and linearly polarized gluon distributions can be extracted by studying different angular distributions.
We discuss a model for soft gluon re-summation based on a statistical description of independent emissions during inelastic collisions. The model is applied to estimate Survival Probabilities at the LHC. A comparison with other models and experimental data is presented.
The free energy of a Quark-Gluon Plasma fireball in the hadronic medium is calculated in the Ramanathan et al. statistical model including the effect of curvature. The result with this curvature is found to produce significant improvement from earlier results in all the parameters we calculated. The surface tension with this curvature effect is found to be $ 0.17 T_{c}^{3}$, which is two times the earlier value of surface tension which is $ 0.078 T_{c}^{3} $, and it is nearly close to the lattice value $0.24 T_{c}^{3} $. The speed of sound calculated with curvature correction is still found to…
We compare the high energy behaviour of hadronic photon-photon cross-sections in different models. We find that the photon-photon cross-section appears to rise faster than the purely hadronic ones (proton-proton and proton-antiproton).
Supersymmetric QCD corrections to the gluonic production and decay rate of a CP-even Higgs boson are evaluated at next-to-leading order. To this aim, we derive an effective Lagrangian for the gluon-Higgs coupling. We show that a consistent calculation requires the inclusion of gluino effects, in contrast to what has been done previously. The supersymmetric corrections to the gluon-Higgs coupling lead to a modification of the next-to-leading order K-factor for the Higgs production rate at the LHC by less than five percent.
In recent decades, the spin and transverse momentum of quarks and gluons were found to play integral roles in the structure of the nucleon. Simultaneously, the onset of gluon saturation in hadrons and nuclei at high energies was predicted to result in a new state of matter dominated by classical gluon fields. Understanding both of these contributions to hadronic structure is essential for current and future collider phenomenology. In this Dissertation, we study the combined effects of transverse spin and gluon saturation using the Glauber-Gribov-Mueller / McLerran-Venugopalan model of a heavy …
The exclusive production of axionlike particles (ALPs) by gluon -- induced interactions is investigated in this exploratory study considering $pp$ and $PbPb$ collisions for the energies of the next run of the Large Hadron Collider (LHC). Assuming the Duhram model, we estimate the associated cross sections for the rapidity ranges probed by central and forward detectors. A comparison with the predictions for the exclusive ALP production by photon -- induced interactions is presented. Our results indicate that the contribution of gluon -- induced interactions is nonnegligible and can become domin…
We propose a simple and easy-to-implement scheme for a renormalon-free gluon condensate (GC) matrix element, which is analogous to implementations of short-distance heavy-quark mass renormalization schemes existing in the literature already for a long time. Because the scheme is based on a perturbative subtraction at the level of the matrix element, with a freely adaptable infrared factorization scale, it can be implemented with little effort for any observable where the GC is relevant. The scheme depends on the renormalon norm of the GC which has to be supplemented independently. We apply the…
We study the transverse single-spin asymmetries for $p^\uparrow p\to π\, X$ and $p^\uparrow p\to γ\, X$ within the so-called color gauge invariant generalized parton model (CGI-GPM) which, in addition to spin and transverse momentum effects, includes initial and final state interactions with the polarized proton remnants. We compute all relevant contributions, focusing in particular on the process dependence of the gluon Sivers function, which, for these processes, can always be expressed as a linear combination of two independent, universal terms. This study extends and completes a previous o…
The MSSM prediction for W+/- H-/+ production by gluon fusion
本文讨论了大型强子对撞机上p p碰撞中伴随的W +/-H-/+产生。在最小超对称标准模型（MSSM）框架下，对环诱导子过程g g-> W +/-H-/+进行了完整的单圈计算，并在squark直接搜索结果和低能精确数据的约束下，研究了强子截面的可能增强.由于三角形图和盒形图中夸克圈贡献的破坏性相互作用很大，所以方圈贡献与夸克圈贡献相当。特别地，在箱型图中，通过胶子熔合的强子截面可以被方对阈值效应显著地增强，从而可以达到与树水平上的通过b b-bar-> W +/-H-/+子过程的强子截面一样大.
Formation of Quark-Gluon Plasma droplets under Ultra-Relativistic Heavy Ion Collisions in the presence of magnetic fields with a modified hadronic medium
Kirori Mal College, University of Delhi（德里大学科里马尔学院）；Tata Institute of Fundamental Research（塔塔基础研究所）
In a recent work by some of us it was shown that the long-standing discrepancy between the QCD perturbation series for the inclusive hadronic tau decay rate computed in the CIPT and FOPT expansion approaches can be understood from the fact that CIPT has an infrared (IR) sensitivity that it not compatible with the standard form of the operator production expansion (OPE). For concrete IR renormalon models for the QCD Adler function the resulting CIPT-FOPT discrepancy, the asymptotic separation, can be calculated analytically from the Borel representation of the CIPT series expansion. If the know…
Soft multiparticle production processes in hadronic collisions are considered in the framework of the Quark-Gluon Strings Model and the model predictions are compared with data from SppS and Tevatron. Predictions for LHC energies are given.
Recently, the ALICE Collaboration reported an enhancement of the yield ratio of strange and multi-strange hadrons to charged pions as a function of multiplicity at mid-rapidity in proton-proton, proton-lead, lead-lead, and xenon-xenon scattering. ALICE observations provide a strong indication that a quark-gluon plasma is partly formed in high multiplicity events of both small and large colliding systems. Motivated by ALICE's results, we propose a new test for hadronic interaction models used for analyzing ultra-high-energy-cosmic-ray (UHECR) collisions with air nuclei. The test is grounded in …
