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We discuss the quark parton structure of the $\Lambda$ baryon and the fragmentation of quarks into $\Lambda$ baryons. We show that the hyperfine interaction, responsible for the $\Delta$-$N$ and $\Sigma^0$-$\Lambda$ mass splittings, leads…

High Energy Physics - Phenomenology · Physics 2010-02-17 C. Boros , J. T. Londergan , A. W. Thomas

In this paper we study transverse polarization of $\Lambda$ hyperons in single-inclusive leptonic annihilation. We show that when the transverse momentum of the $\Lambda$ baryon is measured with respect to the thrust axis, a transverse…

High Energy Physics - Phenomenology · Physics 2022-12-06 Leonard Gamberg , Zhong-Bo Kang , Ding Yu Shao , John Terry , Fanyi Zhao

We demonstrate that spontaneous transverse polarization of Lambda baryon ($\Lambda$) production in $e^+e^-$ annihilation can be described using the transverse momentum dependent polarizing fragmentation functions (TMD PFFs). Using a simple…

High Energy Physics - Phenomenology · Physics 2020-11-18 Daniel Callos , Zhong-Bo Kang , John Terry

We study the production of two almost back-to-back hadrons from the annihilation of an electron and a positron, allowing for the polarization of all particles involved. In particular, we conduct a general (model-independent) structure…

High Energy Physics - Phenomenology · Physics 2015-06-17 D. Pitonyak , M. Schlegel , A. Metz

Spontaneous polarization of $\Lambda/\bar{\Lambda}$ in unpolarized hadron interactions has been observed experimentally for nearly half a century and still eludes a definitive explanation. One possible origin is the effect arising from…

High Energy Physics - Experiment · Physics 2024-02-06 Taoya Gao

We study the measurement of the quark fragmentation functions for spin-1/2 baryon production ($\Lambda$ and $\bar \Lambda$, in particular) in unpolarized $e^+e^-$ annihilation. The spin-dependent fragmentation functions $\hat g_1(z)$ and…

High Energy Physics - Phenomenology · Physics 2010-11-01 Kun Chen , Gary R. Goldstein , R. L. Jaffe , Xiangdong Ji

Data from the Belle Collaboration for associated production (with a light unpolarized hadron) and single-inclusive production of transversely polarized $\Lambda$-hyperons in $e^+e^-$ annihilation processes allowed to extract within a TMD…

High Energy Physics - Phenomenology · Physics 2023-01-18 Marco Zaccheddu , Umberto D'Alesio , Leonard Gamberg , Francesco Murgia

The field of fragmentation functions of light quarks and gluons is reviewed. In addition to integrated fragmentation functions, attention is paid to the dependence of fragmentation functions on transverse momenta and on polarization degrees…

High Energy Physics - Experiment · Physics 2016-10-17 Andreas Metz , Anselm Vossen

A QCD formula for the polarization in the large-p_T \Lambda hyperon production in the unpolarized nucleon-nucleon collision at large x_F is derived. We focus on the mechanism in which the chiral-odd spin-independent twist-3 quark…

High Energy Physics - Phenomenology · Physics 2009-10-31 Y. Kanazawa , Yuji Koike

We suggested that longitudinal polarization of Lambda produced in e+e- annihilation at LEP energies can provide useful information on hadronization mechanism in general and on testing the validity of different pictures for the spin content…

High Energy Physics - Phenomenology · Physics 2007-05-23 Liang Zuo-tang

We investigate the transverse polarization of the $\Lambda$ hyperon in the processes $e^+e^-\to\Lambda^\uparrow \pi^\pm X$ and $e^+e^-\to\Lambda^\uparrow K^\pm X$ within the framework of the transverse momentum dependent~(TMD)…

High Energy Physics - Phenomenology · Physics 2021-04-26 Hui Li , Xiaoyu Wang , Yongliang Yang , Zhun Lu

The surprising polarisation of Lambdas and other hyperons measured in many unpolarised hadronic processes, p N --> Lambda X, has been a long standing challenge for QCD phenomenology. One possible explanation was suggested, related to non…

High Energy Physics - Phenomenology · Physics 2019-08-07 Mauro Anselmino , Raj Kishore , Asmita Mukherjee

The description of the polarized quark hadronization process is one of the most challenging problems in the physics of strong interactions. The various single hadron and dihadron fragmentation functions, that quantify this process, are…

High Energy Physics - Phenomenology · Physics 2019-07-22 Aram Kotzinian , Hrayr H. Matevosyan , Anthony W. Thomas

The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from…

High Energy Physics - Phenomenology · Physics 2016-07-20 Silvia Pisano , Marco Radici

We investigate the ''spontaneous'' hyperon transverse polarization in $e^+e^-$ annihilation and semi-inclusive deep inelastic scattering processes as a test of the universality of the naive-time-reversal-odd transverse momentum dependent…

High Energy Physics - Phenomenology · Physics 2010-12-02 Daniel Boer , Zhong-Bo Kang , Werner Vogelsang , Feng Yuan

Transverse $\Lambda$ polarization observed over four decades ago contradicted expectations from early leading-order perturbative QCD calculations. Measurements of $\Lambda$ polarization from unpolarized $pp$ and $p$A collisions have been…

High Energy Physics - Experiment · Physics 2023-07-18 Cynthia Nunez

We present new sets of fragmentation functions for protons and inclusive charged hadrons obtained in combined NLO QCD analyses of single-inclusive hadron production in electron-positron annihilation, proton-proton collisions, and…

High Energy Physics - Phenomenology · Physics 2008-11-26 Daniel de Florian , Rodolfo Sassot , Marco Stratmann

We analyze experimental data for the production of Lambda baryons in e^+e^- annihilation in terms of scale dependent, QCD evolved, Lambda fragmentation functions. Apart from the vast majority of the data for which the polarization of an…

High Energy Physics - Phenomenology · Physics 2009-10-30 D. de Florian , M. Stratmann , W. Vogelsang

We apply the picture proposed in a recent Letter for transverse hyperon polarization in unpolarized hadron-hadron collisions to the exclusive process e^-p --> e^-HK such as e^-p-->e^-\Lambda K^+, e^-p --> e^-\Sigma^+ K^0, or e^-p-->…

High Energy Physics - Phenomenology · Physics 2015-06-25 Zuo-tang Liang , Qing-hua Xu

We discuss Lambda polarization in semi-inclusive proton-proton collisions, with one of the protons longitudinally polarized. The hyperfine interaction responsible for the $\Delta$-$N$ and $\Sigma$-$\Lambda$ mass splittings gives rise to…

High Energy Physics - Phenomenology · Physics 2010-02-17 C. Boros , J. T. Londergan , A. W. Thomas