nLab LHCb experiment

Idea

The LHCb experiment is one detector/experiment within the Large Hadron Collider (“LHC”) with focus on the physics of B-mesons (similar to the Belle experiment).

After the discovery of the Higgs field at the two major other detectors of LHC, the LHCb experiment currently stands out as seeing (together with the Belle experiment and the BaBar experiment) hints for physics beyond the standard model of particle physics with considerable statistical significance: the flavour anomalies (see there for more).

Related concepts

• related experiments

  • Belle experiment

  • BaBar experiment

• observations

  • flavour anomaly

  • V_cb puzzle

  • pentaquark

  • XYZ particle

• precision experiment

Selected publications

On flavour anomalies

On flavour anomalies:

• Patrick Koppenburg, Selection of $B_u \to \ell \ell K$ at LHCb and Sensitivity to $R_K$, 2007 (cern:1027442, pdf)

• LHCb collaboration, Differential branching fractions and isospin asymmetries of $B \to K^{(\ast)}\mu^+ \mu^-$ decays, JHEP 06 (2014) 133 (arXiv:1403.8044)

• LHCb collaboration, Test of lepton universality using $B^+\to K^+ \ell^+ \ell^-$ decays, Phys. Rev. Lett. 113, 151601 (2014) (arXiv:1406.6482)

• LHCb collaboration, Angular analysis and differential branching fraction of the decay $B^0_s \to \phi \mu^+ \mu^-$, JHEP09(2015)179 (arXivL1506.08777)

• LHCb collaboration, Differential branching fraction and angular analysis of $\Lambda^0_b \to \Lambda \mu^+ \mu^-$ decays, JHEP 06 (2015) 115; JHEP 09 (2018) 145 (arXiv:1503.07138)

• LHCb collaboration, Measurement of the ratio of branching fractions of the decays $\Lambda^0_b \to \psi(2S)\Lambda$ and $\Lambda^0_b \to J/\psi\Lambda$ (arXiv:1902.02092)

• LHCb collaboration, Test of lepton universality using $B^0\to K^{\ast 0} \ell^+ \ell^-$ decays, JHEP 08 (2017) 055 (arXiv:1705.05802)

• LHCb collaboration, Measurement of the ratio of the $B^0 \to D^{\ast -} \tau^+ \vu_\tau$ and $B^0 \to D^{\ast - \mu^+ \nu_\mu}$ branching fractions using three-prong τ-lepton decays (arXiv:1708.08856)

• Paula Alvarez Cartelle on behalf of the LHCb collaboration, New results on flavor anomalies at LHCb, April 2018 (pdf)

• Biplab Dey on behalf of the LHCb collaboration, Flavor anomalies at LHCb, May 2018 (pdf)

• LHCb collaboration, Observation of CP violation in charm decays, March 2019 (pdf, arXiv:1903.08726)

  exposition: LHCb sees a new flavour of matter–antimatter asymmetry, March 2019

• Federico Betti on behalf of LHCb collaboration, Observation of CP violation in charm decays at LHCb, Moriond 2019 (pdf)

• LHCb collaboration, Search for lepton-universality violation in $B^+ \to K^+ \ell^+ \ell^-$ decays (cern:2668514)

• LHCb collaboration, Search for lepton-universality violation in $B^+ \to K^+ \ell^+ \ell^-$ decays (cern:2668514)

• LHCb collaboration, Lepton flavour universality in charged-current $B$ decays (arXiv:1907.01500)

• LHCb collaboration, Test of lepton universality with $\Lambda^0_b\to p K^-\ell^+\ell^-$ decays (arXiv:1912.08139)

  also:

  CERN courier, Debut for baryons in flavour puzzle, 20 Dec. 2019

  CERN news, LHCb explores the beauty of lepton universality, 15 Jan 2020

  (first measurement of lepton universality for $\Lambda^0_b$ Lambda baryons, finding the flavour anomaly at (only) 1 sigma but pointing in the same direction as seen in other channels)

• LHCb collaboration, Measurement of CP-averaged observables in the $B^0 \to K^{\ast 0} \mu^+ \mu^-$ decay (cds:2712641, arXiv:2003.04831)

  exposition:

  Eluned Smith on behalf of the LHCb collaboration, Update of the $B^0 \to K^{\ast 0} \mu^+ \mu^-$ angular analysis at LHCb, 2020 (pdf)

  Ana Lopes, New LHCb analysis still sees previous intriguing results, CERN News 2020

  CERN Courier, Anomalies persist in flavour-changing B decays, March 13 2020

• LHCb collaboration, Measurement of CP-averaged observables in the $B^0\to K^{\ast 0} \mu^+ \mu^-$ decay (spire:1784890, arXiv:2003.04831)

• LHCb collaborationTests of lepton universality using $B^0 \to K^0_S l^+ l^-$− and $B^+ \to K^\ast \ell^+ \ell^-$ decays (arXiv:2110.09501)

• Gregory Max Ciezarek on behalf of the LHCb collaboration: First joint measurement of $R(D^\ast)$ and $R(D^0)$ at LHCb, LHC seminar (2022) [indico:1187939, slides: pdf]

survey:

• Niels Tuning, Recent results from LHCb, Nikhef 2020 (nikhef event:2253, pdf, pdf)

  In recent years a number of results in flavour physics have drawn some attention due to tensions with respect to Standard Model predictions. An overview of these results will be shown, together with a few recent results from this Spring, both on the flavour anomalies and ‘classical’ flavour physics

Claim that the apparent $R_K$-anomalies were due to mis-identification of hadronic backgrounds:

• LHCb collaboration, Test of lepton universality in $b \to s \ell^+ \ell^-$ decays LHCb collaboration [arXiv:2212.09152]

  LHCb collaboration, Measurement of lepton universality parameters in $B^+ \to K^+ \ell^+ \ell^-$ and $B^0 \to K^{\ast 0} \ell^+ \ell^-$ decays [arXiv:2212.09153]

  Davide Castelvecchi, Hint of crack in standard model vanishes in LHC data, Nature News (20 Dec 2022)

On tetraquarks

On tetraquarks:

fully charmed:

• LHCb collaboration, Observation of structure in the $J/\psi$-pair mass spectrum, Science Bulletin 65 (2020) 1983 (arXiv:2006.16957, doi:10.1016/j.scib.2020.08.032, CERN news)

doubly charmed:

• LHCb collaboration, Observation of an exotic narrow doubly charmed tetraquark (arXiv:2109.01038)

• LHCb collaboration, Study of the doubly charmed tetraquark $T^+_{c c}$ (arXiv:2109.01056)

References

• LHCb public page

• LHCb collaboration

• LHCb public results

• LHCb collaboration, Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era (arXiv:1808.08865)

See also

• Wikipedia, LHCb experiment