scholarly journals Angular analysis of $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ with $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ decays

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Helicity Amplitude ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Centre Of Mass ◽  
Mass Energy ◽  
The Third ◽  
Angular Analysis ◽  
Helicity Conservation ◽  
Helicity Amplitudes ◽  
Cabibbo Suppressed

Abstract The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ and D*− → $$ {\overline{D}}^0{\pi}^{-} $$ D ¯ 0 π − vector meson decays are used with the subsequent $$ {D}_s^{+} $$ D s + → K+K−π+ and $$ {\overline{D}}^0 $$ D ¯ 0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ($$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + ) × ℬ($$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ )]/ℬ(B0 → D*−$$ {D}_s^{+} $$ D s + ) is measured to be 2.045 ± 0.022 ± 0.071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed Bs → D*−$$ {D}_s^{+} $$ D s + decay is made with a significance of seven standard deviations. The branching fraction ratio ℬ(Bs → D*−$$ {D}_s^{+} $$ D s + )/ℬ(B0 → D*−$$ {D}_s^{+} $$ D s + ) is measured to be 0.049 ± 0.006 ± 0.003 ± 0.002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractions.

scholarly journals Observation of the decay $$ {\Lambda}_{\mathrm{b}}^0 $$ → χc1pπ−

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Branching Fractions ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Proton Collisions ◽  
Lhcb Detector ◽  
Using Data ◽  
Cabibbo Suppressed ◽  
First Time ◽  
Proton Proton Collisions

Abstract The Cabibbo-suppressed decay $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc1pπ− is observed for the first time using data from proton-proton collisions corresponding to an integrated luminosity of 6 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. Evidence for the $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc2pπ− decay is also found. Using the $$ {\Lambda}_{\mathrm{b}}^0 $$ Λ b 0 → χc1pK− decay as normalisation channel, the ratios of branching fractions are measured to be$$ {\displaystyle \begin{array}{c}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\uppi}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\mathrm{K}}^{-}\right)}=\left(6.59\pm 1.01\pm 0.22\right)\times {10}^{-2},\\ {}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}2}{\mathrm{p}\uppi}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\uppi}^{-}\right)}=0.95\pm 0.30\pm 0.04\pm 0.04,\\ {}\frac{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}2}{\mathrm{p}\mathrm{K}}^{-}\right)}{\mathcal{B}\left({\Lambda}_{\mathrm{b}}^0\to {\upchi}_{\mathrm{c}1}{\mathrm{p}\mathrm{K}}^{-}\right)}=1.06\pm 0.05\pm 0.04\pm 0.04,\end{array}} $$ B Λ b 0 → χ c 1 pπ − B Λ b 0 → χ c 1 pK − = 6.59 ± 1.01 ± 0.22 × 10 − 2 , B Λ b 0 → χ c 2 pπ − B Λ b 0 → χ c 1 pπ − = 0.95 ± 0.30 ± 0.04 ± 0.04 , B Λ b 0 → χ c 2 pK − B Λ b 0 → χ c 1 pK − = 1.06 ± 0.05 ± 0.04 ± 0.04 , where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainties in the branching fractions of χc1,2→ J/ψγ decays.

scholarly journals Measurement of branching fraction ratios for B+ → D*+D−K+, B+ → D*−D+K+, and B0 → D*−D0K+ decays

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Branching Fraction ◽  
Branching Fractions ◽  
Open Charm ◽  
Centre Of Mass ◽  
Final State ◽  
Lhcb Experiment ◽  
The Third ◽  
Three Body ◽  
Integrated Luminosity

Abstract A measurement of four branching-fraction ratios for three-body decays of B mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 pp collision data are used, recorded by the LHCb experiment at centre-of-mass energies 7, 8, and 13 TeV and corresponding to an integrated luminosity of 9 fb−1. The measured branching-fraction ratios are$$ {\displaystyle \begin{array}{c}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast +}{D}^{-}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {\overline{D}}^0{D}^0{K}^{+}\right)}=0.517\pm 0.015\pm 0.013\pm 0.011,\\ {}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast -}{D}^{+}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {\overline{D}}^0{D}^0{K}^{+}\right)}=0.577\pm 0.016\pm 0.013\pm 0.013,\\ {}\begin{array}{c}\frac{\mathcal{B}\left({B}^0\to {D}^{\ast -}{D}^0{K}^{+}\right)}{\mathcal{B}\left({B}^0\to {D}^{-}{D}^0{K}^{+}\right)}=1.754\pm 0.028\pm 0.016\pm 0.035,\\ {}\frac{\mathcal{B}\left({B}^{+}\to {D}^{\ast +}{D}^{-}{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to {D}^{\ast -}{D}^{+}{K}^{+}\right)}=0.907\pm 0.033\pm 0.014,\end{array}\end{array}} $$ B B + → D ∗ + D − K + B B + → D ¯ 0 D 0 K + = 0.517 ± 0.015 ± 0.013 ± 0.011 , B B + → D ∗ − D + K + B B + → D ¯ 0 D 0 K + = 0.577 ± 0.016 ± 0.013 ± 0.013 , B B 0 → D ∗ − D 0 K + B B 0 → D − D 0 K + = 1.754 ± 0.028 ± 0.016 ± 0.035 , B B + → D ∗ + D − K + B B + → D ∗ − D + K + = 0.907 ± 0.033 ± 0.014 , where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the D-meson branching fractions. These are the most accurate measurements of these ratios to date.

SEARCH FOR CHARGINOS AND NEUTRALINOS WITH THE DELPHI DETECTOR AT LEP

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 775-777
Author(s):  
◽  
THOMAS ALDERWEIRELD
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Branching Fraction ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Delphi Detector ◽  
Upper Limit

Search for charginos and neutralinos are presented, based on the data samples recorded in 1999 and 2000 by the DELPHI detector at centre-of-mass energies from 192 to 209 GeV. No evidence for a signal was found. The lower chargino mass limits are 5-6 GeV /c2 higher than those obtained at a centre-of-mass energy of 189 GeV. The (μ, M 2) MSSM domain excluded by combining the chargino searches with neutralino searches at the Z resonance implies a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 37.6 GeV /c2 for tan β≥1. Upper limit at 95% CL on the neutralino production cross-section times branching fraction are derived.

scholarly journals Recent results from BABAR

2020 ◽  
Vol 235 ◽  
pp. 04001
Author(s):  
J. William Gary
Keyword(s):  
Data Collection ◽  
Direct Measurement ◽  
Decay Channel ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Babar Collaboration ◽  
Lepton Number ◽  
Lepton Flavor ◽  
The Third

The BABAR Collaboration at SLAC continues to produce a wide variety of publications on interesting and unique topics despite having ceased data-collection operations more than 10 years ago. Presented here are the results of three recent studies. The first is on the direct measurement of the B± → K± X(3872) branching fraction, allowing the first determination of the branching fractions of the exotic X(3872) charmonium state. The second is a publication on the first observation of the D0 → K−π+e+e− branching fraction. The third is on searches for lepton flavor and lepton number violating decays in D0 meson decays, resulting in improvements over existing limits by factors that vary from 20 to almost 800 depending on the D0 decay channel.

scholarly journals Precise measurements of branching fractions for $$ {\mathrm{D}}_{\mathrm{s}}^{+} $$ meson decays to two pseudoscalar mesons

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
M. Ablikim ◽  
◽  
M. N. Achasov ◽  
P. Adlarson ◽  
S. Ahmed ◽  
...  
Keyword(s):  
Branching Fraction ◽  
Branching Fractions ◽  
External Input ◽  
World Average ◽  
Meson Decays ◽  
Scalar Mesons ◽  
The Third ◽  
Pseudoscalar Mesons ◽  
Pseudo Scalar

Abstract We measure the branching fractions for seven $$ {D}_s^{+} $$ D s + two-body decays to pseudo-scalar mesons, by analyzing data collected at $$ \sqrt{s} $$ s = 4.178 ∼ 4.226 GeV with the BESIII detector at the BEPCII collider. The branching fractions are determined to be$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({D}_s^{+}\to {K}^{+}\eta \hbox{'}\right)=\left(2.68\pm 0.17\pm 0.17\pm 0.08\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to \eta \hbox{'}{\pi}^{+}\right)=\left(37.8\pm 0.4\pm 2.1\pm 1.2\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}\eta \right)=\left(1.62\pm 0.10\pm 0.03\pm 0.05\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to \eta {\pi}^{+}\right)=\left(17.41\pm 0.18\pm 0.27\pm 0.54\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}{K}_S^0\right)=\left(15.02\pm 0.10\pm 0.27\pm 0.47\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}_S^0{\pi}^{+}\right)=\left(1.109\pm 0.034\pm 0.023\pm 0.035\right)\times {10}^{-3},\\ {}\mathcal{B}\left({D}_s^{+}\to {K}^{+}{\pi}^0\right)=\left(0.748\pm 0.049\pm 0.018\pm 0.035\right)\times {10}^{-3},\end{array}} $$ B D s + → K + η ' = 2.68 ± 0.17 ± 0.17 ± 0.08 × 10 − 3 , B D s + → η ' π + = 37.8 ± 0.4 ± 2.1 ± 1.2 × 10 − 3 , B D s + → K + η = 1.62 ± 0.10 ± 0.03 ± 0.05 × 10 − 3 , B D s + → η π + = 17.41 ± 0.18 ± 0.27 ± 0.54 × 10 − 3 , B D s + → K + K S 0 = 15.02 ± 0.10 ± 0.27 ± 0.47 × 10 − 3 , B D s + → K S 0 π + = 1.109 ± 0.034 ± 0.023 ± 0.035 × 10 − 3 , B D s + → K + π 0 = 0.748 ± 0.049 ± 0.018 ± 0.035 × 10 − 3 , where the first uncertainties are statistical, the second are systematic, and the third are from external input branching fraction of the normalization mode $$ {D}_s^{+} $$ D s + → K+K−π+. Precision of our measurements is significantly improved compared with that of the current world average values.

scholarly journals Searches for direct pair production of third generation squarks with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02065
Author(s):  
Nicolas Köhler
Keyword(s):  
Large Hadron Collider ◽  
Standard Model ◽  
Pair Production ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Third Generation ◽  
Centre Of Mass ◽  
Mass Energy ◽  
The Third ◽  
Generation Squarks

Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses not too far from those of their Standard Model counterparts. Top or bottom squarks with masses less than or around one TeV can also give rise to direct pair production rates at the Large Hadron Collider (LHC) that can be observed in the data sample recorded by the ATLAS detector. This document presents recent ATLAS results from searches for direct top and bottom squark pair production considering both R-parity conserving and R-parity violating scenarios, using the data collected during the LHC Run 2 at a centre-of-mass energy of √s = 13 TeV.

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 Next-to-leading-order QCD corrections to a vector bottomonium radiative decay into a charmonium

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Yu-Dong Zhang ◽  
Feng Feng ◽  
Wen-Long Sang ◽  
Hong-Fei Zhang
Keyword(s):  
Decay Width ◽  
Radiative Decay ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Leading Order ◽  
Good Opportunity ◽  
Decay Widths ◽  
Helicity Amplitudes ◽  
Order Of Magnitude ◽  
Theory And Experiment

Abstract Within the framework of nonrelativistic QCD (NRQCD) factorization, we calculate the next-to-leading-order (NLO) perturbative corrections to the radiative decay Υ → ηc(χcJ) + γ. Both the helicity amplitudes and the helicity decay widths are obtained. It is the first computation for the processes involving both bottomonium and charmonium at two-loop accuracy. By employing the Cheng-Wu theorem, we are able to convert most of complex-valued master integrals (MIs) into real-valued MIs, which makes the numerical integration much efficient. Our results indicate the $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s corrections are moderate for ηc and χc2 production, and are quite marginal for χc0 and χc1 production. It is impressive to note the NLO corrections considerably reduce the renormalization scale dependence in both the decay widths and the branching fractions for χcJ, and slightly improve that for ηc. With the NRQCD matrix elements evaluated via the Buchmüller-Tye potential model, we find the decay width for ηc production is one-order-of-magnitude larger than χcJ production, which may provide a good opportunity to search for Υ → ηc + γ in experiment. In addition, the decay width for χc1 production is several times larger than those for χc0,2. Finally, we find the NLO NRQCD prediction for the branching fraction of Υ → χc1 + γ is only half of the lower bound of the experimental data measured recently by Belle. Moreover, there exists serious contradiction between theory and experiment for Υ → ηc + γ. The discrepancies between theory and experiment deserve further research efforts.

scholarly journals Search for long-lived particles decaying to $$e ^\pm $$ $$\mu ^\mp $$ $$\nu $$

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Pair Production ◽  
Cross Section ◽  
Production Cross ◽  
Branching Fraction ◽  
Charged Current ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Upper Limits ◽  
Lhcb Detector ◽  
Current Production

AbstractLong-lived particles decaying to $${e ^\pm } {\mu ^\mp } {\nu } $$ e ± μ ∓ ν , with masses between 7 and $$50 \,\text {GeV/}c^2 $$ 50 GeV/ c 2 and lifetimes between 2 and $$50 \,\text {ps} $$ 50 ps , are searched for by looking at displaced vertices containing electrons and muons of opposite charges. The search is performed using $$5.4 \,\text {fb} ^{-1} $$ 5.4 fb - 1 of $$p $$ p $$p $$ p collisions collected with the LHCb detector at a centre-of-mass energy of $$\sqrt{s} = 13 \,\text {TeV} $$ s = 13 TeV . Three mechanisms of production of long-lived particles are considered: the direct pair production from quark interactions, the pair production from the decay of a Standard-Model-like Higgs boson with a mass of $$125 \,\text {GeV/}c^2 $$ 125 GeV/ c 2 , and the charged current production from an on-shell $$W $$ W boson with an additional lepton. No evidence of these long-lived states is obtained and upper limits on the production cross-section times branching fraction are set on the different production modes.

scholarly journals Search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c.

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
M. Ablikim ◽  
M. N. Achasov ◽  
P. Adlarson ◽  
S. Ahmed ◽  
...  
Keyword(s):  
Confidence Level ◽  
Branching Fraction ◽  
Center Of Mass ◽  
Leptonic Decay ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Upper Limit ◽  
Electron Positron

Abstract Using 10.1 × 109J/ψ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy $$ \sqrt{s} $$ s = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(J/ψ → D−e+νe + c. c.) < 7.1 × 10−8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.

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