| 1. |
- Angeles-Martinez, R., et al.
(författare)
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Transverse Momentum Dependent (TMD) Parton Distribution Functions: Status and Prospects
- 2015
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Ingår i: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 46:12, s. 2501-2534
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Tidskriftsartikel (refereegranskat)abstract
- We review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q(T) spectra of Higgs and vector bosons for low q(T), and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present the application of a new tool, TMDLIB, to parton density fits and parameterizations.
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| 2. |
- Bijnens, Johan, et al.
(författare)
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Leading logarithms for mesons and nucleons
- 2015
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Ingår i: Proceedings of Science. - 1824-8039.
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Tidskriftsartikel (refereegranskat)abstract
- This talk describes the work done in calculating leading logarithms in massive effective field theories. We discuss shortly leading logarithms in renormalizable theories and how they can be calculated using only one-loop calculations in effective field theories. The remainder of the talk discusses masses, decay constants, condensates and anomalous processes in mesonic effective field theories like Chiral Perturbation Theory and the expansion of the nucleon mass.
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| 3. |
- Bijnens, Johan, et al.
(författare)
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Leading logarithms for the nucleon mass
- 2015
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213. ; 891, s. 700-719
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Tidskriftsartikel (refereegranskat)abstract
- Within the heavy baryon chiral perturbation theory approach, we have studied the leading logarithm behavior of the nucleon mass up to four-loop order exactly and we present some results up to six-loop order as well as an all-order conjecture. The same methods allow to calculate the main logarithm multiplying the terms with fractional powers of the quark mass. We calculate thus the coefficients of m(2n+1) log((n-1)) (mu(2)/m(2)) and m(2n+2) log(n) (mu(2)/m(2)) with m the lowest-order pion mass. A side result is the leading divergence for a general heavy baryon loop integral. (C) 2014 The Authors. Published by Elsevier B.V.
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| 4. |
- Diakonov, Dmitri, et al.
(författare)
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Theory of baryon resonances at large N-c
- 2013
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 88:7
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Tidskriftsartikel (refereegranskat)abstract
- At large number of colors, N-c quarks in baryons are in a mean field of definite space and flavor symmetry. We write down the general Lorentz and flavor structure of the mean field, and derive the Dirac equation for quarks in that field. The resulting baryon resonances exhibit a hierarchy of scales: the crude mass is O(N-c), the intrinsic quark excitations are O(1), and each intrinsic quark state entails a finite band of collective excitations that are split as O(1/N-c). We build a (new) theory of these collective excitations, where the full dynamics is represented by only a few constants. In a limiting (but unrealistic) case when the mean field is spherically and flavor symmetric, our classification of resonances reduces to the SU(6) classification of the old nonrelativistic quark model. Although in the real world N-c is only three, we obtain a good accordance with the observed resonance spectrum up to 2 GeV.
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| 5. |
- Echevarria, Miguel, et al.
(författare)
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Transverse momentum dependent fragmentation function at next-to-next-to-leading order
- 2016
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 93:1
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Tidskriftsartikel (refereegranskat)abstract
- We calculate the unpolarized transverse momentum dependent fragmentation function at next-to-next-to-leading order, evaluating separately the transverse momentum dependent (TMD) soft factor and the TMD collinear correlator. For the first time, the cancellation of spurious rapidity divergences in a properly defined individual TMD beyond the first nontrivial order is shown. This represents a strong check of the given TMD definition. We extract the matching coefficient necessary to perform the transverse momentum resummation at next-to-next-to-next-to-leading-logarithmic accuracy. The universal character of the soft function, which enters the definition of all (un)polarized TMD distribution/fragmentation functions, facilitates the future calculation of all the other TMDs and their coefficients at next-to-next-to-leading order, pushing forward the accuracy of theoretical predictions for the current and next generation of high energy colliders.
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| 6. |
- Menkveld, Albert J., et al.
(författare)
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Nonstandard Errors
- 2024
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Ingår i: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
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Tidskriftsartikel (refereegranskat)abstract
- In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
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| 7. |
- Moiseeva, A., et al.
(författare)
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Chiral Expansion of Nucleon PDF at x similar to m(pi)/M-N
- 2014
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Ingår i: Few-Body Systems. - : Springer Science and Business Media LLC. - 0177-7963 .- 1432-5411. ; 55:5-7, s. 389-394
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Tidskriftsartikel (refereegranskat)abstract
- Based on the chiral perturbation theory, we investigate the low-energy dynamics of nucleon parton distributions. We show that in different regions of the momentum fraction x the chiral expansion is significantly different. For nucleon parton distributions these regions are characterized by x similar to 1, x similar to m(pi)/M-N and x similar to (m(pi)/M-N)(2). We derive extended counting rules for each region and obtain model-independent results for the nucleon parton distributions down to x greater than or similar to m(pi)(2)/M-N(2) approximate to 10(-2).
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| 8. |
- Vladimirov, Alexey A., et al.
(författare)
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Leading chiral logarithms for the nucleon mass
- 2016
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Ingår i: XIth Conference on Quark Confinement and Hadron Spectrum. - : AIP Publishing LLC. - 9780735413481 ; 1701
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Konferensbidrag (refereegranskat)abstract
- We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.
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| 9. |
- Vladimirov, Alexey
(författare)
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Exponentiation for products of Wilson lines within the generating function approach
- 2015
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :6
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Tidskriftsartikel (refereegranskat)abstract
- We present the generating function approach to the perturbative exponentiation of correlators of a product of Wilson lines and loops. The exponentiated expression is presented in closed form as an algebraic function of correlators of known operators, which can be seen as a generating function for web diagrams. The expression is naturally split onto two parts: the exponentiation kernel, which accumulates all non-trivial information about web diagrams, and the defect of exponentiation, which reconstructs the matrix exponent and is a function of the exponentiation kernel. The detailed comparison of the presented approach with existing approaches to exponentiation is presented as well. We also give examples of calculations within the generating function exponentiation, namely, we consider different configurations of light-like Wilson lines in the multi-gluon-exchange-webs (MGEW) approximation. Within this approximation the corresponding correlators can be calculated exactly at any order of perturbative expansion by only algebraic manipulations. The MGEW approximation shows violation of the dipole formula for infrared singularities at three-loop order.
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| 10. |
- Vladimirov, Alexey
(författare)
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Generating function for web diagrams
- 2014
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 90:6
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Tidskriftsartikel (refereegranskat)abstract
- We present the description of the exponentiated diagrams in terms of generating function within the universal diagrammatic technique. In particular, we show the exponentiation of the gauge theory amplitudes involving products of an arbitrary number of Wilson lines of arbitrary shapes, which generalizes the concept of web diagrams. The presented method gives a new viewpoint on the web diagrams and proves the non-Abelian exponentiation theorem.
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