Abstract
We study the spin correlations to probe time-reversal (T) asymmetries in the decays of Λb → ΛV (V = ϕ, ρ0, ω, K∗0). The eigenstates of the T-odd operators are obtained along with definite angular momenta. We obtain the T-odd spin correlations from the complex phases among the helicity amplitudes. We give the angular distributions of Λb → Λ(→ pπ−)V (→ PP′) and show the corresponding spin correlations, where P(′) are the pseudoscalar mesons. Due to the helicity conservation of the s quark in Λ, we deduce that the polarization asymmetries of Λ are close to −1. Since the decay of Λb → Λϕ in the standard model (SM) is dictated by the single weak phase from the product of CKM elements, \( {V}_{tb}{V}_{ts}^{\ast } \), the true T and CP asymmetries are suppressed, providing a clean background to test the SM and search for new physics. In the factorization approach, as the helicity amplitudes in the SM share the same complex phase, T-violating effects are absent. Nonetheless, the experimental branching ratio of Br(Λb → Λϕ) = (5.18 ± 1.29) × 10−6 suggests that the nonfactorizable effects or some new physics play an important role. By parametrizing the nonfactorizable contributions with the effective color number, we calculate the branching ratios and direct CP asymmetries. We also explore the possible T-violating effects from new physics.
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G. Bélanger and C. Q. Geng, T violating muon polarization in Kμ3 decays, Phys. Rev. D 44 (1991) 2789 [INSPIRE].
P. Agrawal, J. N. Ng, G. Bélanger and C. Q. Geng, CP violation in \( {K}^{+}\to {\pi}^{+}l\overline{l} \) decays, Phys. Rev. Lett. 67 (1991) 537 [INSPIRE].
C. Q. Geng and J. N. Ng, Testing discrete symmetries with the decay η → π+ π− γ, Phys. Scripta T 99 (2002) 109.
W. Bensalem, A. Datta and D. London, T violating triple product correlations in charmless Λb decays, Phys. Lett. B 538 (2002) 309 [hep-ph/0205009] [INSPIRE].
W. Bensalem, A. Datta and D. London, New physics effects on triple product correlations in Λb decays, Phys. Rev. D 66 (2002) 094004 [hep-ph/0208054] [INSPIRE].
C. Q. Geng and Y. K. Hsiao, T violation in \( {\overline{B}}^0\to \Lambda \overline{p}{\pi}^{+} \), Phys. Rev. D 72 (2005) 037901 [INSPIRE].
C. Q. Geng and Y. K. Hsiao, Direct CP and T Violation in Baryonic B Decays, Int. J. Mod. Phys. A 23 (2008) 3290 [arXiv:0801.0022] [INSPIRE].
C.-H. Chen, C.-Q. Geng and L. Li, New CP phase of \( {B}_s\hbox{-} {\overline{B}}_s \) mixing on T violation in Bd(s) → K∗(ϕ) ℓ+ ℓ−, Phys. Lett. B 670 (2009) 374 [arXiv:0808.0127] [INSPIRE].
R.-H. Li, C.-D. Lu and W. Wang, Branching ratios, forward-backward asymmetries and angular distributions of \( B\to {K}_2^{\ast }{l}^{+}{l}^{-} \) in the standard model and new physics scenarios, Phys. Rev. D 83 (2011) 034034 [arXiv:1012.2129] [INSPIRE].
C. Q. Geng and C.-W. Liu, Searching for possible evidences of new physics in B → V1V2, arXiv:2106.10628 [INSPIRE].
J. G. Korner and M. Krämer, Exclusive nonleptonic charm baryon decays, Z. Phys. C 55 (1992) 659 [INSPIRE].
J. Hrivnac, R. Lednicky and M. Smizanska, Feasibility of beauty baryon polarization measurement in Λ0J/ψ decay channel by ATLAS LHC, J. Phys. G 21 (1995) 629 [hep-ph/9405231] [INSPIRE].
C.-W. Chiang and L. Wolfenstein, Observables in the decays of B to two vector mesons, Phys. Rev. D 61 (2000) 074031 [hep-ph/9911338] [INSPIRE].
Z. J. Ajaltouni, E. Conte and O. Leitner, Λb decays into Λ-vector, Phys. Lett. B 614 (2005) 165 [hep-ph/0412116] [INSPIRE].
O. Leitner, Z. J. Ajaltouni and E. Conte, An Angular distribution analysis of Λb decays, Nucl. Phys. A 755 (2005) 435 [hep-ph/0412131] [INSPIRE].
O. Leitner and Z. J. Ajaltouni, Testing CP and Time Reversal Symmetries with Λb → ΛV (1−) Decays, Nucl. Phys. B Proc. Suppl. 174 (2007) 169 [hep-ph/0610189] [INSPIRE].
T. Gutsche, M. A. Ivanov, J. G. Korner, V. E. Lyubovitskij and P. Santorelli, Rare baryon decays Λb → Λl+ l− (l = e, μ, τ ) and Λb → Λγ: differential and total rates, lepton- and hadron-side forward-backward asymmetries, Phys. Rev. D 87 (2013) 074031 [arXiv:1301.3737] [INSPIRE].
T. Gutsche, M. A. Ivanov, J. G. Körner, V. E. Lyubovitskij and P. Santorelli, Polarization effects in the cascade decay Λb → Λ(→ pπ−) + J/ψ(→ ℓ+ ℓ−) in the covariant confined quark model, Phys. Rev. D 88 (2013) 114018 [arXiv:1309.7879] [INSPIRE].
T. Gutsche, M. A. Ivanov, J. G. Körner and V. E. Lyubovitskij, Nonleptonic two-body decays of single heavy baryons ΛQ, ΞQ, and ΩQ (Q = b, c) induced by W emission in the covariant confined quark model, Phys. Rev. D 98 (2018) 074011 [arXiv:1806.11549] [INSPIRE].
C. Q. Geng, C.-W. Liu and T.-H. Tsai, Asymmetries of anti-triplet charmed baryon decays, Phys. Lett. B 794 (2019) 19 [arXiv:1902.06189] [INSPIRE].
J.-Y. Cen, C.-Q. Geng, C.-W. Liu and T.-H. Tsai, Up-down asymmetries of charmed baryon three-body decays, Eur. Phys. J. C 79 (2019) 946 [arXiv:1906.01848] [INSPIRE].
C. Q. Geng, C.-W. Liu and T.-H. Tsai, Charmed Baryon Weak Decays with Vector Mesons, Phys. Rev. D 101 (2020) 053002 [arXiv:2001.05079] [INSPIRE].
Y.-S. Li, X. Liu and F.-S. Yu, Revisiting semileptonic decays of Λb(c) supported by baryon spectroscopy, Phys. Rev. D 104 (2021) 013005 [arXiv:2104.04962] [INSPIRE].
F. Huang and Q.-A. Zhang, Angular Distributions for Multi-body Semileptonic Charmed Baryon Decays, arXiv:2108.06110 [INSPIRE].
Particle Data Group collaboration, Review of Particle Physics, PTEP 2020 (2020) 083C01 [INSPIRE].
BaBar collaboration, Rates, polarizations, and asymmetries in charmless vector-vector B decays, in 17th Les Rencontres de Physique de la Vallee d’Aoste: Results and Perspectives in Particle Physics, (2003) [hep-ex/0303020] [INSPIRE].
Belle collaboration, Measurement of branching fractions and polarization in B → ϕK(∗) decays, Phys. Rev. Lett. 91 (2003) 201801 [hep-ex/0307014] [INSPIRE].
ATLAS collaboration, Measurement of the parity-violating asymmetry parameter αb and the helicity amplitudes for the decay \( {\Lambda}_b^0 \) → J/ψ + Λ0 with the ATLAS detector, Phys. Rev. D 89 (2014) 092009 [arXiv:1404.1071] [INSPIRE].
CMS collaboration, Measurement of the Λb polarization and angular parameters in Λb → J/ψΛ decays from pp collisions at \( \sqrt{s} \) = 7 and 8 TeV, Phys. Rev. D 97 (2018) 072010 [arXiv:1802.04867] [INSPIRE].
LHCb collaboration, Measurement of the \( {\Lambda}_b^0 \) → J/ψΛ angular distribution and the \( {\Lambda}_b^0 \) polarisation in pp collisions, JHEP 06 (2020) 110 [arXiv:2004.10563] [INSPIRE].
LHCb collaboration, Observation of the decay \( {\Lambda}_b^0 \) → pK − μ+ μ− and a search for CP violation, JHEP 06 (2017) 108 [arXiv:1703.00256] [INSPIRE].
LHCb collaboration, Observation of the \( {\Lambda}_b^0 \) → Λϕ decay, Phys. Lett. B 759 (2016) 282 [arXiv:1603.02870] [INSPIRE].
LHCb collaboration, First Observation of the Radiative Decay \( {\Lambda}_b^0 \) → Λγ, Phys. Rev. Lett. 123 (2019) 031801 [arXiv:1904.06697] [INSPIRE].
A. Dery, M. Ghosh, Y. Grossman and S. Schacht, SU(3)F analysis for beauty baryon decays, JHEP 03 (2020) 165 [arXiv:2001.05397] [INSPIRE].
J. Franklin, Quark model relations for b-baryon decay, J. Phys. G 47 (2020) 085001 [arXiv:2004.01037] [INSPIRE].
J.-J. Han, R.-X. Zhang, H.-Y. Jiang, Z.-J. Xiao and F.-S. Yu, Weak decays of bottom-charm baryons: ℬbc → ℬbP, Eur. Phys. J. C 81 (2021) 539 [arXiv:2102.00961] [INSPIRE].
S. Roy, R. Sinha and N. G. Deshpande, Nonleptonic beauty baryon decays and CP asymmetries based on an SU(3)-flavor analysis, Phys. Rev. D 101 (2020) 036018 [arXiv:1911.01121] [INSPIRE].
S. Roy, R. Sinha and N. G. Deshpande, Beauty baryon nonleptonic decays into decuplet baryons and C P -asymmetries based on an SU(3)-flavor analysis, Phys. Rev. D 102 (2020) 053007 [arXiv:2006.16813] [INSPIRE].
A. Khodjamirian, C. Klein, T. Mannel and Y. M. Wang, Form Factors and Strong Couplings of Heavy Baryons from QCD Light-Cone Sum Rules, JHEP 09 (2011) 106 [arXiv:1108.2971] [INSPIRE].
Z.-X. Zhao, Weak decays of heavy baryons in the light-front approach, Chin. Phys. C 42 (2018) 093101 [arXiv:1803.02292] [INSPIRE].
C. Q. Geng and Y. K. Hsiao, Search for direct CP-violation in baryonic b-hadron decays, Mod. Phys. Lett. A 31 (2016) 1630021 [INSPIRE].
Y. K. Hsiao, Y. Yao and C. Q. Geng, Charmless two-body anti-triplet b-baryon decays, Phys. Rev. D 95 (2017) 093001 [arXiv:1702.05263] [INSPIRE].
C. Q. Geng, C.-W. Liu and T.-H. Tsai, Non-leptonic two-body decays of \( {\Lambda}_b^0 \) in light-front quark model, Phys. Lett. B 815 (2021) 136125 [arXiv:2102.01552] [INSPIRE].
C.-Q. Geng, C.-W. Liu and T.-H. Tsai, Nonleptonic two-body weak decays of Λb in modified MIT bag model, Phys. Rev. D 102 (2020) 034033 [arXiv:2007.09897] [INSPIRE].
A. Ali, G. Kramer and C.-D. Lu, Experimental tests of factorization in charmless nonleptonic two-body B decays, Phys. Rev. D 58 (1998) 094009 [hep-ph/9804363] [INSPIRE].
J. Zhu, Z.-T. Wei and H.-W. Ke, Semileptonic and nonleptonic weak decays of \( {\Lambda}_b^0 \), Phys. Rev. D 99 (2019) 054020 [arXiv:1803.01297] [INSPIRE].
C.-D. Lu, Y.-M. Wang, H. Zou, A. Ali and G. Kramer, Anatomy of the pQCD Approach to the Baryonic Decays Λb → pπ, pK, Phys. Rev. D 80 (2009) 034011 [arXiv:0906.1479] [INSPIRE].
M. Jacob and G. C. Wick, On the General Theory of Collisions for Particles with Spin, Annals Phys. 7 (1959) 404 [INSPIRE].
W. K. Tung, Group Theory in Physics, World Scientific Publishing Company (1985) [INSPIRE].
BESIII collaboration, Polarization and Entanglement in Baryon-Antibaryon Pair Production in Electron-Positron Annihilation, Nature Phys. 15 (2019) 631 [arXiv:1808.08917] [INSPIRE].
A. McKerrell, Relativistic two and three-particle states, Nuovo Cim. 34 (1964) 1289.
Belle collaboration, Measurements of branching fractions and asymmetry parameters of \( {\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0} \), \( {\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0} \), and \( {\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -} \) decays at Belle, JHEP 06 (2021) 160 [arXiv:2104.10361] [INSPIRE].
A. J. Buras, M. Jamin, M. E. Lautenbacher and P. H. Weisz, Effective Hamiltonians for ∆S = 1 and ∆B = 1 nonleptonic decays beyond the leading logarithmic approximation, Nucl. Phys. B 370 (1992) 69 [Addendum ibid. 375 (1992) 501] [INSPIRE].
R. Perez-Marcial, R. Huerta, A. Garcia and M. Avila-Aoki, Predictions for Semileptonic Decays of Charm Baryons. 2. Nonrelativistic and MIT Bag Quark Models, Phys. Rev. D 40 (1989) 2955 [Erratum ibid. 44 (1991) 2203] [INSPIRE].
P. Ball and R. Zwicky, Bd,s → ρ, ω, K∗, ϕ decay form-factors from light-cone sum rules revisited, Phys. Rev. D 71 (2005) 014029 [hep-ph/0412079] [INSPIRE].
H.-Y. Cheng and C.-K. Chua, Revisiting Charmless Hadronic B(u, d) Decays in QCD Factorization, Phys. Rev. D 80 (2009) 114008 [arXiv:0909.5229] [INSPIRE].
H.-Y. Cheng and C.-K. Chua, QCD Factorization for Charmless Hadronic Bs Decays Revisited, Phys. Rev. D 80 (2009) 114026 [arXiv:0910.5237] [INSPIRE].
Z.-T. Zou, A. Ali, C.-D. Lu, X. Liu and Y. Li, Improved Estimates of The B(s) → VV Decays in Perturbative QCD Approach, Phys. Rev. D 91 (2015) 054033 [arXiv:1501.00784] [INSPIRE].
Q. Chang, X.-N. Li, J.-F. Sun and Y.-L. Yang, Fits of Weak Annihilation and Hard Spectator Scattering Corrections in Bu,d → VV Decays, J. Phys. G 43 (2016) 105004 [arXiv:1610.02747] [INSPIRE].
Q. Chang, X. Li, X.-Q. Li and J. Sun, Study of the weak annihilation contributions in charmless Bs → VV decays, Eur. Phys. J. C 77 (2017) 415 [arXiv:1706.06138] [INSPIRE].
C. Wang, Q.-A. Zhang, Y. Li and C.-D. Lu, Charmless B(s) → VV Decays in Factorization-Assisted Topological-Amplitude Approach, Eur. Phys. J. C 77 (2017) 333 [arXiv:1701.01300] [INSPIRE].
M. Bauer, B. Stech and M. Wirbel, Exclusive Nonleptonic Decays of D-, Ds -, and B-Mesons, Z. Phys. C 34 (1987) 103 [INSPIRE].
H.-Y. Cheng and K.-C. Yang, Charmless B → VV decays in QCD factorization: Implications of recent B → ϕK∗ measurement, Phys. Lett. B 511 (2001) 40 [hep-ph/0104090] [INSPIRE].
A. L. Kagan, Right-handed currents, CP-violation, and B → VV, hep-ph/0407076 [INSPIRE].
S. Alioli, V. Cirigliano, W. Dekens, J. de Vries and E. Mereghetti, Right-handed charged currents in the era of the Large Hadron Collider, JHEP 05 (2017) 086 [arXiv:1703.04751] [INSPIRE].
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Geng, CQ., Liu, CW. Time-reversal asymmetries and angular distributions in Λb → ΛV. J. High Energ. Phys. 2021, 104 (2021). https://doi.org/10.1007/JHEP11(2021)104
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DOI: https://doi.org/10.1007/JHEP11(2021)104