Beyond the SM searches with LHCb. Highlights from 2019. · 2020. 2. 11. · 1) Tests of Lepton...

Compostela, Jan-2020 1

Beyond the SM searches withLHCb. Highlights from 2019.

Universidade de Santiago de Compostela (USC)Instituto Galego de Física de Altas Enerxías (IGFAE)

High Energy Physics Group


Study of the B0 → 𝝆𝝆 𝟕𝟕𝟕𝟕𝟕𝟕 𝟕𝟕𝑲𝑲∗ 𝟖𝟖𝟖𝟖𝟖𝟖 𝟕𝟕 decay with an amplitude analysis of B0 → 𝝅𝝅+𝝅𝝅− 𝑲𝑲+𝝅𝝅− decays, arXiv:1812.07008, JHEP05 (2019) 026.

Study of the B0 → 𝝆𝝆 𝟕𝟕𝟕𝟕𝟕𝟕 𝟕𝟕𝑲𝑲∗ 𝟖𝟖𝟖𝟖𝟖𝟖 𝟕𝟕 decay

• Fit model accounting for 10 decay channels leading to 14 interfering amplitudes. Leading contribution of penguin (loop) diagrams.

• Small longitudinal polarisation fraction and significant direct CP asymmetry measured in theB0→ 𝝆𝝆 𝟕𝟕𝟕𝟕𝟕𝟕 𝟕𝟕𝑲𝑲∗ 𝟖𝟖𝟖𝟖𝟖𝟖 𝟕𝟕 decay mode.

María Vieites Díaz Thesis. �𝑩𝑩𝟕𝟕𝑩𝑩𝟕𝟕


Study of the B0 → 𝝆𝝆 𝟕𝟕𝟕𝟕𝟕𝟕 𝟕𝟕𝑲𝑲∗ 𝟖𝟖𝟖𝟖𝟖𝟖 𝟕𝟕 decay


Study of the 𝑩𝑩𝟕𝟕 → 𝑲𝑲+𝝅𝝅− 𝑲𝑲−𝝅𝝅+ decay

Brais Sanmartín Sedes Thesis.

• U-spin partner of Bs0 → K∗0K∗0 decay.

– Can be used to control penguin pollution from subleading amplitudes

• First LHCb analysis of B0 → K∗0K∗0.• Longitudinal polarization very high

compared with Bs0 → K∗0K∗0.

• Untagged and time-integrated analysis.• Assuming ∆Γ ∼ 0 and CP violation

negligible in the mixing and in the decay.

• Longitudinal pol. fraction measured to be fL= 0.724 ± 0.051 (stat.) ± 0.016 (syst.). For the 𝑩𝑩𝒔𝒔𝟕𝟕 → 𝑲𝑲∗𝟕𝟕�𝑲𝑲∗𝟕𝟕 decay we have fL= 0.201 ± 0.057 (stat.) ± 0.040 (syst.)

• The decay branching fraction is also measured, improving the previous statistical uncert. by a factor of 2: 𝑩𝑩𝑩𝑩 𝑩𝑩𝟕𝟕 → 𝑲𝑲∗𝟕𝟕�𝑲𝑲∗𝟕𝟕 = 𝟖𝟖.𝟕𝟕 ± 𝟕𝟕.𝟖𝟖 𝒔𝒔𝒔𝒔𝒔𝒔𝒔𝒔 ± 𝟕𝟕.𝟒𝟒 𝒔𝒔𝒔𝒔𝒔𝒔𝒔𝒔 × 𝟏𝟏𝟕𝟕−𝟕𝟕

= 𝟑𝟑.𝟒𝟒𝟖𝟖 ± 𝟕𝟕.𝟑𝟑𝟖𝟖

𝑦𝑦 = ⁄ΔΓ𝑠𝑠 2Γ𝑠𝑠

Amplitude analysis of the 𝑩𝑩(𝒔𝒔)𝟕𝟕 → 𝑲𝑲∗𝟕𝟕�𝑲𝑲∗𝟕𝟕 decays and measurement of the Br. Fract. of the 𝑩𝑩𝟕𝟕 → 𝑲𝑲∗𝟕𝟕�𝑲𝑲∗𝟕𝟕

decay, arXiv:1905.06662, JHEP07 (2019) 032.


LHCb B(s)0→VV papers with IGFAE contact authors

1) Amplitude analysis of the B(s)0→ K∗0K∗0 decays and measurement of the branching fraction of the B0→

K∗0K∗0. JHEP 07 (2019) 032. arXiv:1905.06662. PAPER-2019-004.

2) Study of the B0→ρ(770)0K∗(892)0 mode with an amplitude analysis of B0→(π±π∓)(K+π−) decays. JHEP 05 (2019) 026. arXiv:1812.07008. 3 citations. PAPER-2018-042.

3) First measurement of the CP-violating phase ϕsdd in B0

s→(K+π−)(K−π+) decays. JHEP 03 (2018) 140. arXiv:1712.08683. 12 citations. PAPER-2017-048.

4) Measurement of CP violation parameters and polarisation fractions in Bs0→J/ψK∗0 decays. JHEP 11

(2015) 082. arXiv:1509.00400. 35 citations. PAPER-2015-034.

5) Observation of the B0→ρ0ρ0 decay from an amplitude analysis of B0→(π+π−)(π+π−) decays. Phys. Lett. B747 (2015) 468. arXiv:1503.07770. 23 citations. PAPER-2015-006.

6) Measurement of CP asymmetries and polarisation fractions in Bs0→K∗0K∗0 decays. JHEP 07 (2015)

166. arXiv:1503.05362. 20 citations. PAPER-2014-068.

7) Measurement of polarization amplitudes and CP asymmetries in B0→ϕK∗0. JHEP 05 (2014) 069. arXiv:1403.2888. 31 citations. PAPER-2014-005.

8) First observation of the decay Bs0→ϕK∗0. JHEP 11 (2013) 92. arXiv:1306.2239. 16 citations. PAPER-2013-

012.

9) Measurement of Bs0→J/ψK∗0 branching fraction and angular amplitudes. Phys. Rev. D86 (2012)

071102(R). arXiv:1208.0738. 43 citations. PAPER-2012-014.

10) First observation of the decay Bs0→K∗0K∗0. Phys. Lett. B709 (2012) 50. arXiv:1111.4183. 57 citations.

PAPER-2011-012.

http://arxiv.org/abs/arXiv:1812.07008

https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2018-042.html




















LHCb B(s)0→ VV PhD Theses

1) Study of the 𝐵𝐵𝑠𝑠0 ⟶ ρ 770 0𝐾𝐾∗(892)0 decay with an amplitude analysis of 𝐵𝐵𝑠𝑠0 →𝜋𝜋+𝜋𝜋− 𝐾𝐾+𝜋𝜋− decays. María Vieites Díaz, 27/03/2019. Now at EPFL.

2) Search for flavour lepton anomalies at LHCb: decay-time-dependent CP violation in 𝐵𝐵𝑠𝑠0 → 𝐾𝐾+𝜋𝜋− 𝐾𝐾−𝜋𝜋+ and Lepton Universality in 𝐵𝐵0 → 𝐷𝐷 ∗ +𝑙𝑙𝜈𝜈𝑙𝑙. Julián García Pardiñas, 11/06/2018. Not at Zurich University.

3) Study of the decay 𝐵𝐵𝑠𝑠0 ⟶ 𝐾𝐾∗0 �𝐾𝐾∗0 and first observation of the 𝐵𝐵𝑠𝑠0 ⟶ 𝜙𝜙�𝐾𝐾∗0 decay at the LHCb experiment. Brais Sanmartín Sedes, 19/12/2017.

4) An approach to new physics at LHCb: study of penguin pollution to 𝜙𝜙𝑠𝑠 𝐵𝐵𝑠𝑠0 ⟶ J/𝜓𝜓𝜙𝜙using 𝐵𝐵𝑠𝑠0 ⟶ J/𝜓𝜓�𝐾𝐾∗0decays, and search for a light 𝐴𝐴10 Higgs boson in the NMSSM. Carlos Vázquez Sierra, 14/12/2016. Now at NIKHEF.

5) Study of the penguin-dominated decay 𝐵𝐵𝑠𝑠0 ⟶ 𝐾𝐾∗0 �𝐾𝐾∗0 at LHCb. Paula Álvarez Cartelle, 21/11/2014. Now at Imperial College.


Lepton flavour universality tests

• Study of semitauonic B decays with 3-prong hadronic 𝛕𝛕→3𝛑𝛑𝛎𝛎𝛕𝛕 decays.

• Experimental method based on cut on distance between tau and B vertices.

𝑅𝑅𝐷𝐷(∗) ≡ℬ 𝐵𝐵 → 𝐷𝐷(∗)𝜏𝜏�̅�𝜈𝜏𝜏ℬ 𝐵𝐵 → 𝐷𝐷(∗)ℓ�̅�𝜈ℓℓ = 𝜇𝜇, 𝑒𝑒

• Review of Lepton Universality tests in B decays. J.Phys. G46 (2019) no.2, 023001.

• Measurement of the ratio of the 𝑩𝑩𝟕𝟕 → 𝑫𝑫∗−𝝉𝝉+𝝂𝝂𝝉𝝉 and 𝑩𝑩𝟕𝟕 → 𝑫𝑫∗−𝝁𝝁+𝝂𝝂𝝁𝝁 branching fractions using three-prong tau-lepton decays, Phys. Rev. Lett. 120, 17802 (2018).

• Test of lepton flavour universality by the measurement of the 𝑩𝑩𝟕𝟕 → 𝑫𝑫∗−𝝉𝝉+𝝂𝝂𝝉𝝉 branching fraction using three-prong decays, Phys. Rev. D 97, 072013 (2018).



𝑹𝑹 𝑫𝑫∗ World average 2.𝟓𝟓 𝝈𝝈 above SM prediction.𝑹𝑹 𝑫𝑫∗ + 𝑹𝑹(𝑫𝑫) measurements show an overall 𝟑𝟑.𝟕𝟕 𝝈𝝈 tension with the SM.

New measurements in a variety of decay channels are being performed.

𝑹𝑹 𝑫𝑫∗ 𝑹𝑹 𝑫𝑫∗

𝑹𝑹 𝑫𝑫

𝑹𝑹 𝑫𝑫∗ vs. 𝑹𝑹 𝑫𝑫



Short term goals:

• Combined measurements of R(D)and R(D*) in 𝑩𝑩𝟕𝟕 → 𝑫𝑫(∗)−𝝉𝝉+𝝂𝝂𝝉𝝉 and 𝑩𝑩− → 𝑫𝑫(∗)𝟕𝟕𝝉𝝉+𝝂𝝂𝝉𝝉 decays.

• R(D) not measured by LHCb yet. Only by B-factories Belle and BaBar.

• Use 2015+2016 LHCb data to perform a first measurement.

• Then, include all available 2011-2018 data.

• Now studying main backgrounds by using data-driven control samples.

𝒒𝒒𝟖𝟖 = 𝒎𝒎𝝉𝝉𝝂𝝂𝟖𝟖

𝑩𝑩 → 𝑫𝑫𝑫𝑫𝒔𝒔+𝑿𝑿 control sample


Lepton flavour universality tests: charm sector

• Study of semileptonic 𝒄𝒄 → 𝒔𝒔 transitions, measuring

• Extraction of the yields from two different fit frameworks:• Bidimensional template fit to

• Bidimensional template fit to and , where the neutrino momentum is obtained using a “Global fit” algorithm (GF)

• The value of 𝑹𝑹𝒆𝒆/𝝁𝝁 is blinded in the fit

• 𝐷𝐷0 from prompt • 2015-2016 data sample 𝑠𝑠 = 13 TeV,

1.9 𝑓𝑓𝑓𝑓−1• Measurement in bins of 𝒒𝒒𝟖𝟖

𝑹𝑹𝒆𝒆/𝝁𝝁 =𝓑𝓑 𝑫𝑫𝟕𝟕 → 𝑲𝑲−𝒆𝒆+𝝂𝝂𝒆𝒆𝓑𝓑 𝑫𝑫𝟕𝟕 → 𝑲𝑲−𝝁𝝁+𝝂𝝂𝝁𝝁


LFU LHCb publications

1) Test of lepton flavor universality by the measurement of the B0→D∗−τ+ντ branching fraction using three-prong τ decays. Phys. Rev. D 97, 072013. arXiv:1711.02505. 143 citations. PAPER-2017-027

2) Measurement of the ratio of the B(B0→D∗−τ+ντ) and B(B0→D∗−μ+νμ) branching fractions using three-prong τ-lepton decays. Phys. Rev. Lett. 120, 171802. arXiv:1708.08856. 165 citations. PAPER-2017-017

3) Test of LFU with charm semileptonic decays at the LHCb experiment. In preparation.

1) Tests of Lepton Flavour Universality using semitauonic B decays in the LHCbExperiment at CERN . Beatriz García Plana. Expected in 2020.

2) Testing Lepton Flavor Universality with B->Dtaunu and B->D*taunu decays at LHCb. Alessandra Gioventù. Expected in 2021.

3) Measurements of Lepton Universality in semileptonic decays of b-quark hadrons in LHCb. Julián Lomba. Expected in 2021.

LFU PhD theses






Heavy Ions at LHCb

Nuclear modification factor. For an incoherent superposition of nucleon-nucleon collisions 𝑹𝑹𝐩𝐩𝐩𝐩𝐩𝐩 = 𝟏𝟏

Study prompt charged particle production.

Charged particle multiplicities can yield information on Cold Nuclear Matter effects (CNM) in p-Pb collisions.CNM effects are also expected in Pb-Pb collisions.

ALICE, CMS and ATLAS only cover LHCb can explore a much wider region:


p-Pb and p-p LHCb papers with IGFAE contact authors

1) Measurement of the inelastic pp cross-section at a centre-of-mass energy of √s=13 TeV. JHEP 06 (2018) 100. arXiv:1803.10974. 9 citations. PAPER-2018-003

2) Nuclear Modification Factor of Charged Primary Particle Spectra in pPb/Pbp/pp Collisions at 5 TeV. In preparation.

1) Measurement of the inelastic pp cross-sections using the LHCb experiment and development of a new vertex detector. Álvaro Dosil Suárez. 5/5/2017.

2) Multiplicities Analysis in Proton-Lead Collisions at the LHCb Experiment. Óscar Boente García. Expected in 2020.

3) New PhD student to start in February 2020: Sara Sellam, shared with the Phenomenology group. European Funding through the STRONG-2020 Grant.

p-Pb and p-p LHCb PhD theses

Diffractive Physics Workshop in May 2020




LHCb Upgrade phase-I: LS2 and the VELO upgrade

• “Old” Inner Tracker (IT) dismantled at LHCb cavern

• VELO readout system developments:• FPGA clustering algorithms • First version of the firmware completed• TFC system for the back-end electronics

• VELO detector construction:• 320 High-speed data links assembled and certified• 190 High Voltage cables produced and tested• Feedthrough and OPB assembling


LHCb Upgrade phase-I: LS2 and the VELO upgrade

• VELO readout chain integration and test:• BER and TDR measurements• Optical tests w the final 400 meters optical fibres • First version of the firmware validated• TFC system for the back-end electronics tested

• Integration of a complete VELO slide:• Cooling, electronics, LV and HV modules, monitoring

• Conference and workshop organization:• VELO firmware workshop at Santiago (January)

• VELO Upgrade II workshop at Villars (February)

• TWEPP 2019 conference at Santiago. (September)

• VELO firmware integration workshop . (October)

• Clustering integration workshop at Pisa. (October)

• PhD Thesis of Antonio Fernández Prieto:Development of electronics for the VELO upgrade detector


Backup slides


LHC SCHEDULE









𝑹𝑹 𝑫𝑫∗ 𝑹𝑹 𝑫𝑫

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Beyond the SM searches with LHCb. Highlights from 2019. · 2020. 2. 11. · 1) Tests of Lepton...

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