Framework for identification of neutral<i>B</i>mesons

Gronau, Michael; Rosner, Jonathan L.

doi:10.1103/physrevlett.72.195

Cited by 15 publications

(18 citation statements)

References 14 publications

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“…As noted in Refs. [7] and [8], the component Q ′ 3 does not appear in these expressions. We shall return to the question of its determination in Section VI.…”

Section: Density-matrix Descriptionmentioning

confidence: 99%

“…[7,8], it is necessary to observe decays to CP eigenstates and not just to flavor eigenstates in order to fully specify the density matrix, since the element Q ′ 3 does not appear in any of the previous expressions for rates. We consider decays to J/ψK S and J/ψK L .…”

Section: Full Specification Of the Density Matrixmentioning

confidence: 99%

“…Although we shall generally speak of the (B 0 , B 0 ) system, many of our results apply as well to neutral strange B mesons. In Section II we rederive a density-matrix formalism first introduced in [7,8], using a more standard phase convention and correcting a sign error in the original references. This formalism is then applied to several cases, including mixed states with dilution of tagging efficiency (Section III), full coherence (Section IV), and intermediate cases (Section V).…”

Section: Introductionmentioning

confidence: 99%

“…The dynamics of B meson production affords several methods for identifying this flavor. "Same-side" tagging methods [5,6,7,8] utilize the correlation of the flavor of a neutral B with the charge of a kaon or pion which is produced near it in phase space. "Opposite-side" methods utilize the associated production of bb in electromagnetic or strong interactions to tag a neutral B using the fragmentation products of the quark produced in association with it.…”

Section: Introductionmentioning

confidence: 99%

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Erratum: Tests for coherence in neutralBmeson decays [Phys. Rev. D 63, 054006 (2001)]

Gronau¹,

Rosner²

2001

Phys. Rev. D

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A density-matrix method for the study of tagged states of neutral B mesons with arbitrary coherence properties is applied to several examples, including e + e − production both at and above the Υ(4S) resonance, and hadronic production. In the absence of coherence the only term modulating the exponential decay of a neutral B meson behaves as cos ∆mt, while a sin ∆mt modulation is a signal of partial or full coherence. Decays to CP eigenstates are needed to fully specify the density matrix. We relate these results to more familiar expressions for the cases of the Υ(4S) and incoherent production. I IntroductionNeutral B mesons undergo time-dependent oscillations with their antiparticles. This feature, first demonstrated for neutral kaons nearly half a century ago [1], has been crucial in extracting fundamental information on the mechanism of CP violation from the decays of neutral B's. Moreover, the oscillations themselves have provided crucial information on the magnitude of electroweak couplings, and were one of the first pieces of evidence for a very heavy top quark [2].The oscillations are characterized by splittings ∆m between mass eigenstates. For the B d =bd, the most recent world average [3] is ∆m d = 0.487 ± 0.014 ps −1 . For the B s =bs, only a lower limit [3,4] ∆m s > 15 ps −1 exists at present.1 To be submitted to Phys. Rev. D.

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“…As noted in Refs. [7] and [8], the component Q ′ 3 does not appear in these expressions. We shall return to the question of its determination in Section VI.…”

Section: Density-matrix Descriptionmentioning

confidence: 99%

Section: Full Specification Of the Density Matrixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Erratum: Tests for coherence in neutralBmeson decays [Phys. Rev. D 63, 054006 (2001)]

Gronau¹,

Rosner²

2001

Phys. Rev. D

Self Cite

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“…Considering the crudeness of the assumptions made in the original paper in addition to SU(3), the method has been extended until a high level of sophistication by several authors [6]. As a consequence, it is not clear to what extent such complicated geometrical constructions, plagued by multiple discrete ambiguities, are sensitive to α and to the unavoidable theoretical assumptions.…”

Section: Introductionmentioning

confidence: 99%

Taming the penguin contributions in theBd0(t)→π+<

Charles

1999

Phys. Rev. D

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Penguin contributions, being not negligible in general, can hide the information on the CKM angle α coming from the measurement of the timedependent B 0 d (t) → π + π − CP-asymmetry. Nevertheless, we show that this information can be summarized in a set of simple equations, expressing α as a multi-valued function of a single theoretically unknown parameter, which conveniently can be chosen as a well-defined ratio of penguin to tree amplitudes. Using these exact analytic expressions, free of any assumption besides the Standard Model, and some reasonable hypotheses to constrain the modulus of the penguin amplitude, we derive several new upper bounds on the penguin-induced shift |2α − 2α eff |, generalizing the recent result of Grossman and Quinn. These bounds depend on the average branching ratios of some decays (π 0 π 0 , K 0 K 0 , K ± π ∓ ) particularly sensitive to the penguin. On the other hand, with further and less conservative approximations, we show that the knowledge of the B ± → Kπ ± branching ratio alone gives sufficient information to extract the free parameter without the need of other measurements, and without knowing |V td | or |V ub |. More generally, knowing the modulus of the penguin amplitude with an accuracy of ∼ 30% might result in an extraction of α competitive with the experimentally more difficult isospin analysis. We also show that our framework allows to recover most of the previous approaches in a transparent and simple way, and in some cases to improve them. In addition we discuss in detail the problem of the various kinds of discrete ambiguities.

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Boosted Ensembles of Qubit and Continuous Variable Quantum Support Vector Machines for B Meson Flavor Tagging

West,

Sevior,

Usman

2023

Adv Quantum Tech

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The recent physical realization of quantum computers with hundreds of noisy qubits has given birth to an intense search for useful applications of their unique capabilities. One area that has received particular attention is quantum machine learning (QML), the study of machine learning algorithms running natively on quantum computers. In this work, QML methods are developed and applied to B meson flavor tagging, an important component of experiments which probe CP violation in order to better understand the matter‐antimatter asymmetry of the universe. One simulate boosted ensembles of quantum support vector machines (QSVMs) based on both conventional qubit‐based and continuous variable architectures, attaining effective tagging efficiencies of 28.0% and 29.2%, respectively, comparable with the leading published result of 30.0% using classical machine learning algorithms. The ensemble nature of the classifier is of particular importance, doubling the effective tagging efficiency of a single QSVM, which is find to be highly prone to overfitting. These results are obtained despite the constraint of working with QSVM architectures that are classically simulable, and it finds evidence that QSVMs beyond the simulable regime may be able to realize even higher performance, when sufficiently powerful quantum hardware is developed to execute them.

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Framework for identification of neutralBmesons

Cited by 15 publications

References 14 publications

Erratum: Tests for coherence in neutralBmeson decays [Phys. Rev. D 63, 054006 (2001)]

Erratum: Tests for coherence in neutralBmeson decays [Phys. Rev. D 63, 054006 (2001)]

Taming the penguin contributions in theBd0(t)→π+<

Boosted Ensembles of Qubit and Continuous Variable Quantum Support Vector Machines for B Meson Flavor Tagging

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