Transversity and Λ polarization in semi-inclusive DIS




Transversity, quantum-chromodynamics, lambda hyperon, SIDIS, COMPASS


Several possible experimental channels have been proposed in the past to access the chiral-odd transversity distribution functions h1. Among these, the measurements of target-transverse-spin asymmetries in single-hadron and hadron-pair production in Semi-Inclusive Deep Inelastic Scattering (SIDIS) gave clear evidence that transversity is measurable and sizable in the valence region. A third, independent channel is the measurement of the polarization of Λ hyperons produced in SIDIS off transversely polarized nucleons, where the transverse polarization of the struck quark might be transferred to the final-state hyperon. The COMPASS Collaboration at CERN has measured the transversityinduced polarization of Λ and Λ¯ hyperons produced in SIDIS off transversely polarized protons, found compatible with zero. The results are shown here and discussed in the context of different models and approximations


J. P. Ralston and D. E. Soper, Production of dimuons from high-energy polarized proton proton collisions, Nucl. Phys. B 152 (1979) 109,

F. Baldracchini, N. S. Craigie, V. Roberto, and M. Socolovsky, A survey of polarization asymmetries predicted by QCD, Fortsch. Phys. 30 (1981) 505,

X. Artru and M. Mekhfi, Transversely polarized parton densities, their evolution and their measurement, Z. Phys. C 45 (1990) 669,

R. L. Jaffe, X.-D. Ji, Chiral odd parton distributions and polarized Drell-Yan, Phys. Rev. Lett. 67 (1991) 552–555.

A. Airapetian et al., Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target, Phys. Rev. Lett. 94 (2005) 012002,

A. Airapetian et al., Effects of transversity in deep-inelastic scattering by polarized protons, Phys. Lett. B 693 (2010) 11, 08.012,

M. G. Alekseev et al., Measurement of the Collins and Sivers asymmetries on transversely polarised protons, Phys. Lett. B 692 (2010) 240,

C. Adolph et al., Experimental investigation of transverse spin asymmetries in muon-p SIDIS processes: Collins asymmetries, Phys. Lett. B 717 (2012) 376,

A. Airapetian et al., Evidence for a transverse single-spin asymmetry in leptoproduction of π +π − pairs, JHEP 06 (2008) 017,

C. Adolph et al., Transverse spin effects in hadron-pair production from semi-inclusive deep inelastic scattering, Phys. Lett. B 713 (2012) 10,

C. Adolph et al., A high-statistics measurement of transverse spin effects in dihadron production from muon–proton semiinclusive deep-inelastic scattering, Phys. Lett. B 736 (2014) 124,

A. Martin, F. Bradamante, and V. Barone, Extracting the transversity distributions from single-hadron and dihadron production, Phys. Rev. D 91 (2015) 014034,

M. Anselmino, M. Boglione, U. D’Alesio, S. Melis, F. Murgia, and A. Prokudin, Simultaneous extraction of transversity and Collins functions from new SIDIS and e +e − data, Phys. Rev. D 87 (2013) 094019,

Z.-B. Kang, A. Prokudin, P. Sun, and F. Yuan, Extraction of quark transversity distribution and Collins fragmentation functions with QCD evolution, Phys. Rev. D 93 (2016) 014009,

H.-W. Lin, W. Melnitchouk, A. Prokudin, N. Sato, and H. Shows, First Monte Carlo global analysis of nucleon transversity with lattice QCD constraints, Phys. Rev. Lett. 120 (2018) 152502,

M. Radici and A. Bacchetta, First extraction of transversity from a global analysis of electron-proton and proton-proton data, Phys. Rev. Lett. 120 (2018) 192001,

X. Artru and M. Mekhfi, What can we learn from unpolarized and polarized electroproduction of fast baryons?, Nucl. Phys. A 532 (1991) 351,

R. L. Jaffe, Polarized Λ’s in the current fragmentation region, Phys. Rev. D 54 (1996) R6581.

M. Anselmino, Transversity and Lambda polarization, in: Workshop on Future Physics at COMPASS, 2003.

M. Anselmino, M. Boglione, and F. Murgia, Λ and Λ¯ polarization in polarized DIS, Phys. Lett. B 481 (2000) 253,

V. Barone and P. G. Ratcliffe, Transverse spin physics, (Vol. River Edge, 2003).

M. Ablikim et al., Polarization and entanglement in baryonantibaryon pair production in electron-positron annihilation, Nature Phys. 15 (2019) 631,

A. Kotzinian, New quark distributions and semiinclusive electroproduction on the polarized nucleons, Nucl. Phys. B 441 (1995) 234,

P. J. Mulders, and R. D. Tangerman, The complete tree level result up to order 1/Q for polarized deep inelastic leptoproduction, Nucl. Phys. B 461 (1996) 197, [Erratum: Nucl. Phys. B 484 (1997) 538],

G. Bunce et al., Λ 0 hyperon polarization in inclusive production by 300-GeV protons on Beryllium., Phys. Rev. Lett. 36 (1976) 1113,

P. Abbon et al., The COMPASS experiment at CERN, Nucl. Instrum. Meth. A 577 (2007) 455,

P. Abbon et al., Particle identification with COMPASS RICH-1, Nucl. Instrum. Meth. A 631 (2011) 26,

J. Podolanski and R. Armenteros, III. Analysis of V-events, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 45 (1954) 13,

R. Armenteros, K. Barker, C. Butler, A. Cachon, and C. York, LVI. The properties of charged V-particles, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 43 (1952) 597,

G. Ingelman, A. Edin, and J. Rathsman, LEPTO 6.5: A Monte Carlo generator for deep inelastic lepton - nucleon scattering, Comput. Phys. Commun. 101 (1997) 108,

C. Adolph et al., Study of Σ(1385) and Ξ(1321) hyperon and antihyperon production in deep inelastic muon scattering, Eur. Phys. J. C 73 (2013) 2581,

V. Y. Alexakhin, et al., First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering, Phys. Rev. Lett. 94 (2005) 202002,

E. S. Ageev et al., A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target, Nucl. Phys. B 765 (2007) 31,

J. Adam et al., Transverse spin transfer to Λ and Λ¯ hyperons in polarized proton-proton collisions at √ s = 200 GeV, Phys. Rev. D 98 (2018) 091103,

B.-Q. Ma, I. Schmidt, J.-J. Yang, Ratio of Λ¯ / Λ in semiinclusive electroproduction, Phys. Lett. B 574 (2003) 35,

A. Rastogi, Polarized and unpolarized baryon production: SU(3) revisited, Phys. Rev. D 59 (1999) 114012,

D. Indumathi, H. S. Mani, A. Rastogi, An SU(3) model for octet baryon and meson fragmentation, Phys. Rev. D 58 (1998) 094014,

J.-J. Yang, Flavor and spin structure of quark fragmentation functions in a diquark model for octet baryons, Phys. Rev. D 65 (2002) 094035,

H. L. Lai et al., Global QCD analysis of parton structure of the nucleon: CTEQ5 parton distributions, Eur. Phys. J. C 12 (2000) 375,

J.-J. Yang, q-→ Λ fragmentation function and nucleon transversity distribution in a diquark model, Nucl. Phys. A 699 (2002) 562,

R. Jakob, P. J. Mulders, J. Rodrigues, Modeling quark distribution and fragmentation functions, Nucl. Phys. A 626 (1997) 937,




How to Cite

Moretti A. Transversity and Λ polarization in semi-inclusive DIS. Supl. Rev. Mex. Fis. [Internet]. 2022 May 18 [cited 2024 May 20];3(3):0308078 1-6. Available from: