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Present Status of Inclusive Rare B Decays

Tobias Hurth

TL;DR

This paper assesses the status of inclusive rare B decays, arguing that modes like $B \to X_{s,d} \gamma$, $B \to X_s \ell^+\ell^-$, and $B \to X_s \nu\bar{\nu}$ offer theoretically clean probes of short-distance physics and potential new dynamics. It reviews experimental data from CLEO, BABAR, and BELLE, and details the progression from LL to NNLL QCD calculations, highlighting the charm-mass scheme ambiguity as a dominant theoretical uncertainty that motivates NNLL refinement. The work then analyzes the phenomenological implications for CKM physics and indirect SUSY searches, including CP violation in radiative decays and the sensitivity of Wilson coefficients, as well as the complementary role of rare kaon decays in precision flavor physics. Overall, inclusive rare B decays emerge as a crucial, theoretically robust laboratory for testing the Standard Model and constraining new physics, with significant progress anticipated from upcoming high-luminosity B factories and associated kaon experiments.

Abstract

We give a status report on inclusive rare B decays, highlighting recent developments and open problems. We focus on the decay modes $B \to X_{s,d} γ$, $ B \to X_s \ell^+\ell^-$ and $B \to X_s ν\bar ν$ and on their role in the search for new physics. Most of the inclusive rare B decays are important modes of flavour physics due to the small hadronic uncertainties. They can be regarded as laboratories to search for new physics. We collect the experimental data already available from CLEO and the $B$ factories BABAR and BELLE. We review the NLL and NNLL QCD calculations of the inclusive decay rates that were recently completed, and discuss future prospects, especially the issue of the charm mass scheme ambiguity. Finally, we analyse the phenomenological impact of these decay modes, in particular on the CKM phenomenology and on the indirect search for supersymmetry. We also briefly discuss direct CP violation in inclusive rare B decays, as well as the rare kaon decays $K^+\to π^+ν\barν$ and $K_L \to π^0 ν\barν$, which offer complementary theoretically clean information.

Present Status of Inclusive Rare B Decays

TL;DR

This paper assesses the status of inclusive rare B decays, arguing that modes like , , and offer theoretically clean probes of short-distance physics and potential new dynamics. It reviews experimental data from CLEO, BABAR, and BELLE, and details the progression from LL to NNLL QCD calculations, highlighting the charm-mass scheme ambiguity as a dominant theoretical uncertainty that motivates NNLL refinement. The work then analyzes the phenomenological implications for CKM physics and indirect SUSY searches, including CP violation in radiative decays and the sensitivity of Wilson coefficients, as well as the complementary role of rare kaon decays in precision flavor physics. Overall, inclusive rare B decays emerge as a crucial, theoretically robust laboratory for testing the Standard Model and constraining new physics, with significant progress anticipated from upcoming high-luminosity B factories and associated kaon experiments.

Abstract

We give a status report on inclusive rare B decays, highlighting recent developments and open problems. We focus on the decay modes , and and on their role in the search for new physics. Most of the inclusive rare B decays are important modes of flavour physics due to the small hadronic uncertainties. They can be regarded as laboratories to search for new physics. We collect the experimental data already available from CLEO and the factories BABAR and BELLE. We review the NLL and NNLL QCD calculations of the inclusive decay rates that were recently completed, and discuss future prospects, especially the issue of the charm mass scheme ambiguity. Finally, we analyse the phenomenological impact of these decay modes, in particular on the CKM phenomenology and on the indirect search for supersymmetry. We also briefly discuss direct CP violation in inclusive rare B decays, as well as the rare kaon decays and , which offer complementary theoretically clean information.

Paper Structure

This paper contains 25 sections, 76 equations, 35 figures.

Table of Contents

  1. Introduction
  2. Strong interaction in $B$ decays
  3. Experimental status
  4. Experimental data on $B \rightarrow X_{s} \gamma$
  5. Photon spectrum of $B \rightarrow X_s \gamma$
  6. Experimental status of $B \rightarrow X_s \ell^+\ell^-$ and $B \rightarrow X_d \gamma$
  7. Perturbative calculations in $B \rightarrow X_{s,d}\, \gamma$
  8. Perturbative calculations in $B \rightarrow X_{s} \ell^+\ell^-$ and $B \rightarrow X_s \bar{\nu} \nu$
  9. Non-perturbative contributions
  10. Inclusive decay rates of $B$ mesons
  11. Non-perturbative corrections to $B \rightarrow X_{s,d} \gamma$ and $B \rightarrow X_s \ell^+ \ell^-$
  12. Phenomenology
  13. SM prediction of $B \rightarrow X_s \gamma$
  14. CKM phenomenology with $B \rightarrow X_{s,d} \gamma$
  15. Role of $b \rightarrow s \, {gluon}$ for $B \rightarrow X_{no\, charm}$
  16. ...and 10 more sections

Figures (35)

  • Figure 1: Penguin decays of $B$ mesons.
  • Figure 2: QCD corrections to the decay $B \rightarrow X_s \gamma$.
  • Figure 3: Operator product expansion: full versus effective theory.
  • Figure 4: $e^+ e^- \rightarrow \Upsilon (4 S) \rightarrow B^+ B^- , B^0 \bar{B}^0$.
  • Figure 5: Levels of inclusive photons from various background processes at $\Upsilon (4S)$ and the expected signal from $b \rightarrow s \gamma$: ISR, $B \bar{B}$ and $\pi^0$ backgrounds are shown (from the bottom to the top at $E_\gamma = 0.5$), from experiment2.
  • ...and 30 more figures