New strategy for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>B</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:math>branching ratio measurements and the search for new physics in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi>B</mml:mi><mml:mi>s</mml:mi><mml:mn>0</mml:mn></mml:msubsup><mml:mo>→</mml:mo><mml:msup><mml:mi>μ</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>μ</mml:mi><mml:mo>−</mml:mo></mml:msup></mm

Nuclear Physics B - Proceedings Supplements

2013

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The LHCb experiment has recently established a sizable width difference between the mass eigenstates of the B smeson system. This phenomenon leads to a subtle difference at the 10% level between the experimental branching ratios of B s decays extracted from time-integrated, untagged data samples and their theoretical counterparts. Measuring the corresponding effective B s -decay lifetimes, both branching ratio concepts can be converted into each other. The rare decay B 0 s → µ + µ − and the search for New Physics through this channel is also affected by this effect, which enhances the Standard-Model reference value of the branching ratio by O(10%), while the effective lifetime offers a new observable to search for physics beyond the Standard Model that is complementary to the branching ratio.

Section: Introductionsupporting

confidence: 59%

“…[1]). At the e + e − B factories operating at the Υ(5S ) resonance, B s -decay branching ratios can be extracted since the total number of produced B s mesons can be determined separately [2].…”

Section: Introductionmentioning

confidence: 99%

On Branching Ratios of Bs Decays and the Search for New Physics in Bs0

Nuclear Physics B - Proceedings Supplements

2013

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“…Moreover, its measurement at the LHC is not affected by the ratio f s /f d of fragmentation functions [38], which is an advantage from the experimental point of view.…”

Section: New Physics Benchmark Scenariomentioning

confidence: 90%

In pursuit of new physics with B s,d 0 → ℓ + ℓ −

Tetlalmatzi-Xolocotzi

2017

J. High Energ. Phys.

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Abstract:Leptonic rare decays of B 0 s,d mesons offer a powerful tool to search for physics beyond the Standard Model. The B 0 s → µ + µ − decay has been observed at the Large Hadron Collider and the first measurement of the effective lifetime of this channel was presented, in accordance with the Standard Model. On the other hand, B 0 s → τ + τ − and B 0 s → e + e − have received considerably less attention: while LHCb has recently reported a first upper limit of 6.8 × 10 −3 (95% C.L.) for the B 0 s → τ + τ − branching ratio, the upper bound 2.8 × 10 −7 (90% C.L.) for the branching ratio of B 0 s → e + e − was reported by CDF back in 2009. We discuss the current status of the interpretation of the measurement of B 0 s → µ + µ − , and explore the space for New-Physics effects in the other B 0 s,d → + − decays in a scenario assuming flavour-universal Wilson coefficients of the relevant fourfermion operators. While the New-Physics effects are then strongly suppressed by the ratio m µ /m τ of the lepton masses in B 0 s → τ + τ − , they are hugely enhanced by m µ /m e in B 0 s → e + e − and may result in a B 0 s → e + e − branching ratio as large as about 5 times the one of B 0 s → µ + µ − , which is about a factor of 20 below the CDF bound; a similar feature arises in B 0 d → e + e − . Consequently, it would be most interesting to search for the B 0 s,d → e + e − channels at the LHC and Belle II, which may result in an unambiguous signal for physics beyond the Standard Model.

“…(3.40) and combine them with information on the ratio of branching fractions. The systematic uncertainty of all B s branching ratio measurements is limited by the ratio f s /f d = 0.259 ± 0.015 [43,44] of fragmentation functions, which is required for normalisation purposes [45]. At the LHCb upgrade, the experimental precision of the ratio of branching fractions entering eq.…”

Section: Jhep03(2015)145mentioning

confidence: 99%

A roadmap to control penguin effects in B d 0 → J/ψK S 0 and B s 0 → J/ψϕ

Bruyn

2015

J. High Energ. Phys.

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The theoretical interpretation of the corresponding observables is limited by uncertainties from doubly Cabibbo-suppressed penguin topologies. With continuously increasing experimental precision, it is mandatory to get a handle on these contributions, which cannot be calculated reliably in QCD. In the case of the measurement of sin 2β from B 0 d → J/ψK 0 S , the U -spinrelated decay B 0 s → J/ψK 0 S offers a tool to control the penguin effects. As the required measurements are not yet available, we use data for decays with similar dynamics and the SU(3) flavour symmetry to constrain the size of the expected penguin corrections. We predict the CP asymmetries of B 0 s → J/ψK 0 S and present a scenario to fully exploit the physics potential of this decay, emphasising also the determination of hadronic parameters and their comparison with theory. In the case of the benchmark mode B 0 s → J/ψφ used to determine the B 0 s -B 0 s mixing phase φ s the penguin effects can be controlled through B 0 d → J/ψρ 0 and B 0 s → J/ψK * 0 decays. The LHCb collaboration has recently presented pioneering results on this topic. We analyse their implications and present a roadmap for controlling the penguin effects.