Related papers: Proof of Factorization of Fragmentation Function i…
Fracture functions are parton distributions of an initial hadron in the presence of an almost collinear particle observed in the final state. They are important ingredients in QCD factorization for processes where a particle is produced…
Exclusive processes in hard electroproduction is one of the best place for understanding the factorization properties of QCD. The HERA experiment recently provided precise data for rho electroproduction, including all spin density matrix…
Understanding the interactions between elementary particles and mapping out the internal structure of the hadrons are of fundamental importance in high energy nuclear and particle physics. This thesis concentrates on the strong interaction,…
We present a perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum $p_T$ at collider energies, which includes both the leading power (LP) and next-to-leading power (NLP) contributions to…
In certain situations, such as one-particle inclusive processes, it is possible to model the hadronization through Fragmentation Functions (FFs), which are universal non-perturbative functions extracted from experimental data through…
We test the nonrelativistic QCD factorization conjecture for inclusive quarkonium production at two loops by carrying out a covariant calculation of the nonrelativistic quantum chromodynamics (NRQCD) long-distance matrix element (LDME) for…
It was found that, using nonrelativistic QCD factorization, the predicted $\chi_{cJ}$ hadroproduction cross section at large $p_T$ can be negative. The negative cross sections originate from terms proportional to plus function in…
We discuss factorization in heavy quarkonium production in high energy collisions using NRQCD. Infrared divergences at NNLO are not matched by conventional NRQCD matrix elements. However, we show that gauge invariance and factorization…
We present the first global analysis of fragmentation functions (FFs) for light charged hadrons ($\pi^{\pm}$, $K^{\pm}$) at full next-to-next-to-leading order in Quantum Chromodynamics (QCD), incorporating world data from both…
We show that when the factorized cross section for heavy quarkonium production includes next-to-leading power (NLP) contributions associated with the production of the heavy quark pair at short distances, it naturally reproduces all high…
The widely used nonrelativistic QCD (NRQCD) factorization theory now encounters some notable difficulties in describing quarkonium production. This may be due to the inadequate treatment of soft hadrons emitted in the hadronization process,…
We prove $k_T$ factorization theorem in perturbative QCD (PQCD) for exclusive processes by considering $\pi\gamma^*\to \gamma(\pi)$ and $B\to\gamma(\pi) l\bar\nu$. The relevant form factors are expressed as the convolution of hard…
Input-output theory is a well-known tool in quantum optics and ubiquitous in the description of quantum systems probed by light. Owing to the generality of the setup it describes, the theory finds application in a wide variety of…
Parton fragmentation functions (FFs) are indispensable for understanding processes of hadron production ubiquitously existing in high-energy collisions, but their first principle determination has never been realized due to the…
The next-to-leading order (NLO) ($\mathcal{O}(\alpha_s^3)$) corrections for gluon fragmentation functions to a heavy quark-antiquark pair in ${^{3}\hspace{-0.6mm}P_{J}^{[1,8]}}$ states are calculated within the NRQCD factorization. We use…
We present a QCD study of fragmentation processes for light and heavy quarks in the semi-inclusive region of large x. Large logarithmic terms, due to soft-gluon radiation, are evaluated and resummed to all perturbative orders in the QCD…
We calculate the NLO corrections for the gluon fragmentation functions to a heavy quark-antiquark pair in ${^{1}\hspace{-0.6mm}S_{0}^{[1]}}$ or ${^{1}\hspace{-0.6mm}S_{0}^{[8]}}$ state within NRQCD factorization. We use integration-by-parts…
By expanding functions of parton fragmentation into a heavy hadron in the inverse of the heavy quark mass $m_Q$ we attempt to factorize them into perturbative- and nonperturbative parts. In our approach the nonperturbative parts can be…
We investigate the inclusive hadroproduction of pseudoscalar heavy quarkonia, $\eta_c$ and $\eta_b$ mesons, in high-energy proton collisions. Our framework bases on the single-parton collinear fragmentation within a variable-flavor number…
We study heavy quarkonium production associated with gluons in $\rm e^+e^-$ annihilation as an illustration of the perturbative QCD (pQCD) factorization approach, which incorporates the first nonleading power in the energy of the produced…