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Chen, Chuan Hung; Geng, C. Q.

doi:10.1103/physrevd.64.074001

Cited by 129 publications

(131 citation statements)

References 32 publications

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“…Also, there are good arguments in favor of studying the exclusive Λ b → Λ + − decays on the phenomenological side. First, the polarization asymmetry of the Λ-baryon in the decay products allows a "clean" extraction of the helicity structure of the weak effective Hamiltonian in the factorization limit [4,5]. Second, the angular distribution for the fourbody decays Λ b → Λ(→ N π) + − offers additional information on the Wilson coefficients of effective weak operators [6,7], due to the fact that the cascade weak decay Λ → N π is parity violating.…”

Section: Jhep02(2016)179mentioning

confidence: 99%

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Wang

Shen

2016

J. High Energ. Phys.

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We compute radiative corrections to Λ b → Λ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with Λ b -baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-Λ b -baryon correlation function is justified at leading power in Λ/m b , with the aid of the method of regions. Hard functions entering the factorization formulae are identical to the corresponding matching coefficients of heavy-to-light currents from QCD onto soft-collinear effective theory. The universal jet function from integrating out the hard-collinear fluctuations exhibits richer structures compared with the one involved in the factorization expressions of the vacuum-to-B-meson correlation function. Based upon the QCD resummation improved sum rules we observe that the perturbative corrections at O(α s ) shift the Λ b → Λ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the Λ b → Λ from factors we further investigate several decay observables in the electro-weak penguin Λ b → Λ + − transitions in the factorization limit (i.e., ignoring the "non-factorizable" hadronic effects which cannot be expressed in terms of the Λ b → Λ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

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Section: Jhep02(2016)179mentioning

confidence: 99%

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Wang

Shen

2016

J. High Energ. Phys.

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“…(11), it is necessary to have conditions of (a) the existence of C R k and (b) a phase of C L i C R j (i = j). We remark that these conditions for P Λ T are clearly different from those of the T odd transverse lepton polarizations in both inclusive decay of b → sl + l − [11] and exclusive ones, such as B → K ( * ) l + l − [12] and Λ b → Λl + l − [4,5]. Such property distinguishes the T odd transverse Λ polarizations from various other T odd observables.…”

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confidence: 84%

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confidence: 99%

“…In addition we deem it particularly interesting if the time reversal symmetry violation can be directly detected in the b-system rather than inferring it as a consequence of CPT invariance. In this talk, we will present our recent studies on T violation in the baryonic decays of Λ b → Λl + l − (l = e, µ) [3,4,5,6].It is known that for a general three-body decay * Talk presented by C.Q. Geng at the 5th International Conference on Hyperons, Charm and Beauty Hadrons of a baryon the triple spin-momentum correlations, such as s k ·( p i × p j ), are T-odd observables, where s k and p i,j are the spin and momentum vectors of the final particles, respectively.…”

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confidence: 99%

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T violation in Γb → Γl+l− decays

Chen

Geng

2003

Nuclear Physics B - Proceedings Supplements

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We examine the T-odd transverse lepton and Λ polarizations in the baryonic decays of Λ b → Λl + l − (l = e , µ) to study the T violating effects. We show that the lepton polarizations are suppressed but the Λ ones can be as large as 50% in CP violating theories beyond the standard model such as the SUSY models, which can be tested in various future hadron colliders.Recently, time-reversal violation (TV) has been measured experimentally in the K 0 system [1], and thus complements the information on CP violation (CPV) that has been steadily accumulating for the past thirty seven years. The data is in accordance with the CPT theorem which is fundamental to local quantum field theories with Lorentz invariance and the usual spin-statistics connection. However, the origin of the violation remains unclear. In the standard model, CPV or TV arises from a unique physical phase in the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix [2]. This paradigm also predicts CPV effect in the b-quark system. To test the accuracy of this paradigm and to search for other sources of CPV one needs to look for new processes. Indeed this is an important quest of the B-factories. In addition we deem it particularly interesting if the time reversal symmetry violation can be directly detected in the b-system rather than inferring it as a consequence of CPT invariance. In this talk, we will present our recent studies on T violation in the baryonic decays of Λ b → Λl + l − (l = e, µ) [3,4,5,6].It is known that for a general three-body decay * Talk presented by C.Q. Geng at the 5th International Conference on Hyperons, Charm and Beauty Hadrons of a baryon the triple spin-momentum correlations, such as s k ·( p i × p j ), are T-odd observables, where s k and p i,j are the spin and momentum vectors of the final particles, respectively. There are a number of different sources that might give rise to these T-odd observables. The most important ones being the weak CPV such as the CKM phase of the SM. However, final state interactions such as QCD for non-leptonic decays or the electromagnetic (EM) interaction among the final state particles can also make contributions. These are usually less interesting and they could even hide the signals from the weak CPV. We note that the T-odd triple correlations do not need nonzero strong phases unlike some of CP violating observables, such as the rate asymmetry between a particle and its antiparticle. In Λ b → Λl + l − decays, we can use either the polarization of the lepton (s l ) or the Λ baryon (s Λ ) to study the Todd correlations. It is interesting to note that the decays can be used to analyze the helicity structure of the interaction, which is impossible in the B meson system.We start with the effective Hamiltonian for b → sl + l − by including the right-handed couplings in

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“…Moreover, these measurements could help in the study of b → s decays such as Λ b → µ + µ − Λ [26,27], which are topologically similar to Λ b → J/ψΛ, where J/ψ decays to dimuons. This Letter reports an improved measurement with respect to the previous Tevatron result [28] of the production fraction multiplied by the branching fraction of the Λ b → J/ψΛ decay relative to that of the decay B 0 → J/ψK 0 s .…”

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confidence: 99%