scholarly journals Searches for 25 rare and forbidden decays of D+ and $$ {D}_s^{+} $$ mesons

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Confidence Level ◽  
Branching Fractions ◽  
Proton Collision ◽  
Proton Proton ◽  
Charm Decays ◽  
Lhcb Experiment ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
Integrated Luminosity

Abstract A search is performed for rare and forbidden charm decays of the form $$ {D}_{(s)}^{+}\to {h}^{\pm }{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{\left(\prime \right)\mp } $$ D s + → h ± ℓ + ℓ ′ ∓ , where h± is a pion or kaon and ℓ(′)± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1.6 fb−1, collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1.4 × 10−8 and 6.4 × 10−6. In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.

scholarly journals Study of $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ decays to charmonia and three light hadrons

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
F. J. Abudinen Gallego ◽  
...  
Keyword(s):  
Branching Fractions ◽  
Theoretical Description ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Charged Hadrons ◽  
Lhcb Detector ◽  
Proton Proton Collision ◽  
First Time ◽  
Integrated Luminosity

Abstract Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector, seven decay modes of the $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + meson into a J/ψ or ψ(2S) meson and three charged hadrons, kaons or pions, are studied. The decays $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → (ψ(2S) → J/ψπ+π−)π+, $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → ψ(2S)π+π−π+, $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → J/ψK+π−π+ and $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → J/ψK+K−K+ are observed for the first time, and evidence for the $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → ψ(2S)K+K−π+, decay is found, where J/ψ and ψ(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.

scholarly journals Observation of the $$ {B}_s^0 $$ → D*±D∓ decay

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Branching Fraction ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Proton Proton ◽  
High Significance ◽  
Lhcb Experiment ◽  
The Third ◽  
Proton Proton Collision ◽  
Integrated Luminosity

Abstract A search for the $$ {B}_{\mathrm{s}}^0 $$ B s 0 → D*±D∓ decay is performed using proton-proton collision data at centre-of-mass energies of 7, 8 and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The decay is observed with a high significance and its branching fraction relative to the B0→ D*±D∓ decay is measured to be$$ \frac{\mathrm{\mathcal{B}}\left({B}_s^0\to {D}^{\ast \pm }{D}^{\mp}\right)}{\left({B}^0\to {D}^{\ast \pm }{D}^{\mp}\right)}=0.137\pm 0.017\pm 0.002\pm 0.006, $$ ℬ B s 0 → D ∗ ± D ∓ B 0 → D ∗ ± D ∓ = 0.137 ± 0.017 ± 0.002 ± 0.006 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $$ {B}_{\mathrm{s}}^0 $$ B s 0 and B0 hadronisation fractions.

scholarly journals Measurement of the shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ differential decay rate

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Decay Rate ◽  
Form Factors ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Lhcb Detector ◽  
Proton Proton Collision ◽  
Integrated Luminosity

Abstract The shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb detector. The $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ decay is reconstructed through the decays $$ {D}_s^{\ast -}\to {D}_s^{-}\gamma $$ D s ∗ − → D s − γ and $$ {D}_s^{-}\to {K}^{-}{K}^{+}{\pi}^{-} $$ D s − → K − K + π − . The differential decay rate is fitted with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) parametrisations of the form factors, and the relevant quantities for both are extracted.

scholarly journals Measurement of cross sections and couplings of the Higgs boson in fermionic decay modes with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02119
Author(s):  
Liaoshan Shi
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
The Cross

In this report, we present the latest ATLAS results on the measurement of the cross sections and couplings of the Higgs boson in the fermionic decay modes, H → μ+μ-, H → τ+τ- and H → bb. The searches are performed with proton-proton collision data delivered by the Large Hadron Collider during Run 1 and the first two years of Run 2 at √s = 7, 8 and 13 TeV.

scholarly journals Measurement of the W boson mass

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
...  
Keyword(s):  
Distribution Function ◽  
Parton Distribution ◽  
W Boson ◽  
Parton Distribution Function ◽  
Boson Mass ◽  
Proton Collision ◽  
Proton Proton ◽  
Lhcb Experiment ◽  
Proton Proton Collision ◽  
Pm 10

Abstract The W boson mass is measured using proton-proton collision data at $$ \sqrt{s} $$ s = 13 TeV corresponding to an integrated luminosity of 1.7 fb−1 recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/pT distribution of a sample of W → μν decays and the ϕ* distribution of a sample of Z → μμ decays the W boson mass is determined to be$$ {m}_w=80354\pm {23}_{\mathrm{stat}}\pm {10}_{\mathrm{exp}}\pm {17}_{\mathrm{theory}}\pm {9}_{\mathrm{PDF}}\mathrm{MeV}, $$ m w = 80354 ± 23 stat ± 10 exp ± 17 theory ± 9 PDF MeV , where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.

scholarly journals Search for rare and exotic Higgs Boson decay modes

2018 ◽  
Vol 182 ◽  
pp. 02123
Author(s):  
Junquan Tao
Keyword(s):  
Higgs Boson ◽  
New Physics ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Higgs Decay ◽  
Proton Proton Collision ◽  
8 Tev ◽  
Invisible Decays ◽  
Lepton Flavour

The latest results in the search for rare and exotic Higgs boson decays in proton-proton collision events collected with the CMS detector at the LHC are presented. The searches are performed for several decay modes of Higgs boson including H → X(X → 2ℓ)γ (X = Z, γ* and ℓ = e, μ), H → μμ=ee, invisible decays, lepton flavour violating decays and Higgs decay to light scalars or pseudo-scalars. No hint for new physics has been found from the analyzed results with the full LHC run-1 data collected during 2011 and 2012 at √s = 7-8 TeV and with the run-2 data at √s = 13 TeV collected during 2015 and 2016. Limits are set for all the searches which have been performed by CMS.

scholarly journals XYZ states at LHCb

2019 ◽  
Vol 199 ◽  
pp. 04001
Author(s):  
Marcin Kucharczyk
Keyword(s):  
Proton Collision ◽  
Precision Spectroscopy ◽  
Proton Proton ◽  
Lhcb Experiment ◽  
Exotic States ◽  
Quantum Numbers ◽  
Proton Proton Collision ◽  
Spectroscopy Studies ◽  
Exotic Hadrons

The latest years have observed a resurrection of interest in searches for exotic states motivated by precision spectroscopy studies of beauty and charm hadrons providing the observation of several exotic states. The latest results on spectroscopy of exotic hadrons are reviewed, using the proton-proton collision data collected by the LHCb experiment. The document focuses among others on the confirmation of the resonant nature of the Z(4430) mesonic state and observation of $J/\Psi \phi $ structures consistent with exotic states. LHCb has also made significant contributions to the determination of the quantum numbers of the X(3872) state and excluded the existence of the X(5568) tetraquark candidate.

scholarly journals Searches for supersymmetry with the CMS experiment

2018 ◽  
Vol 182 ◽  
pp. 02060
Author(s):  
Alexis Kalogeropoulos ◽  
Keyword(s):  
Proton Collision ◽  
Proton Proton ◽  
Cms Experiment ◽  
Proton Proton Collision ◽  
Integrated Luminosity

We report on recent results by the CMS Collaboration on searches for supersymmetry based on a sample of proton-proton collision data at √s = 13 TeV, corresponding to a total integrated luminosity of 35.9 fb-1.

scholarly journals Operation and performance of the ATLAS semiconductor tracker in LHC Run 2

2022 ◽  
Vol 17 (01) ◽  
pp. P01013
Author(s):  
Georges Aad ◽  
Brad Abbott ◽  
Dale Charles Abbott ◽  
Adam Abed Abud ◽  
Kira Abeling ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Proton Collision ◽  
Original Design ◽  
Proton Proton ◽  
Pile Up ◽  
Proton Proton Collision ◽  
And Performance ◽  
Full Depletion ◽  
The Impact ◽  
Integrated Luminosity

Abstract The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015–2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb-1 to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules.

scholarly journals Measurement of the branching fraction of the $${{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ decay

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Collision Energy ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Charged Current ◽  
Proton Collision ◽  
Single Measurement ◽  
Proton Proton ◽  
Proton Proton Collision ◽  
Current Transition ◽  
Fraction Measurement

AbstractA branching fraction measurement of the $${{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B 0 → D s + π - decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of $$5.0\,\text {fb} ^{-1} $$ 5.0 fb - 1 . The branching fraction is found to be $${\mathcal {B}} ({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} ) =(19.4 \pm $$ B ( B 0 → D s + π - ) = ( 19.4 ± $$1.8\pm 1.3 \pm 1.2)\times 10^{-6}$$ 1.8 ± 1.3 ± 1.2 ) × 10 - 6 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + , $${{D} ^+_{s}} {\rightarrow }{{K} ^+} {{K} ^-} {{\pi } ^+} $$ D s + → K + K - π + and $${{D} ^-} {\rightarrow }{{K} ^+} {{\pi } ^-} {{\pi } ^-} $$ D - → K + π - π - branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a $$b{\rightarrow }u$$ b → u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element $$V_{ub}$$ V ub . Additionally, the collision energy dependence of the hadronisation-fraction ratio $$f_s/f_d$$ f s / f d is measured through $${{\overline{B}} {}^0_{s}} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $$ B ¯ s 0 → D s + π - and $${{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} $$ B 0 → D - π + decays.

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