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Applications of QCD Effective Theories to the Physics of Jets and Quarkonium Production

Dai, Lin (2018) Applications of QCD Effective Theories to the Physics of Jets and Quarkonium Production. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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We apply QCD effective theories to study the physics of jets and quarkonium production. The thesis contains work in the following two related directions.

The first direction is jet physics (chapter 3 of the thesis). We introduced a function called fragmentation function to a jet (FFJ) to describe inclusive jet production from a parton and studied FFJs in different phase space and momentum regions. One of the limits we investigated was where the jet radius r was small, which lead to large log(r) corrections that need to be resummed. Another limit was the large z limit, where z was defined to be the fraction of energy carried by the jet from the mother parton. Here log(1-z) can appear and is due to the gluon radiations that are both collinear and soft (described by collinear-soft fields). We formulated factorization theorems and used renormalization group techniques to deal with these types of logarithms. Phenomenologically, both the small jet radius and large z limit are important for comparing precision calculations with experimental data.

The second direction is quarkonium production in jets (chapter 4 of the thesis). This direction naturally combines jet physics with quarkonium production. Since quarkonium production in a jet is inclusive in the jet, we can still use inclusive quarkonium fragmentation functions that are perturbatively calculable based on the Non-relativistic QCD (NRQCD) factorization formalism. We did both analytic calculations and Monte Carlo simulations and compared them with the recent LHCb measurement of J/psi production in jets. We found that currently existing event generators are not sufficient to study quarkonium production in jets and we proposed modifications (e.g., to PYTHIA). Both our analytic calculations and the modified PYTHIA agreed reasonably well with the LHCb data. Our study indicates that the detailed dynamics of quarkonium production in jets can help us better understand quarkonium production mechanisms. We also studied other observables related to quarkonium production in jets that could have the potential power to clarify quarkonium production mechanisms.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Dai, Linlin.dai@pitt.edulid330000-0002-0802-6884
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairLeibovich,
Committee MemberBoudreau,
Committee MemberHan,
Committee MemberMorningstar,
Committee MemberZentner,
Date: 26 September 2018
Date Type: Publication
Defense Date: 6 April 2018
Approval Date: 26 September 2018
Submission Date: 11 July 2018
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 180
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Effective Field Theory, QCD, Quarkonium, Jets, SCET, NRQCD
Date Deposited: 26 Sep 2018 23:41
Last Modified: 26 Sep 2018 23:41

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  • Applications of QCD Effective Theories to the Physics of Jets and Quarkonium Production. (deposited 26 Sep 2018 23:41) [Currently Displayed]


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