Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “LHCB”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Search for CP violation using $\hat{T}$-odd correlations in $B^0→p⁢\overline{p}K^{+}⁢\pi^-$ decays

A search for CP and P violation in charmless four-body B 0 → p$\overline{p}$K + ⁢π – decays is performed using triple-product asymmetry observables. It is based on proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 8.4 fb –1 . The CP- and P-violating asymmetries are measured both in the integrated phase space and in specific regions. No evidence is seen for CP violation. P-parity violation is observed at a significance of 5.8 standard deviations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Study of charmonium decays to K S 0 K π in the B → ( K S 0 K π ) K channels

A study of the B + → $K^0_S$K + K - π + and B + → $K^0_S$K + K + π - decays is performed using proton-proton collisions at center-of-mass energies of 7, 8 and 13 TeV at the LHCb experiment. The $K^0_S$Kπ invariant mass spectra from both decay modes reveal a rich content of charmonium resonances. New precise measurements of the η c and η c (2S) resonance parameters are performed and branching fraction measurements are obtained for B + decays to η c , J/ψ, η c (2S) and χ c1 resonances. In particular, the first observation and branching fraction measurement of B + → χ c0 K 0 π + is reported as well as first measurements of the B + → K 0 K + K - π + and B + → K 0 K + K - π + branching fractions. Dalitz plot analyses of η c → $K^0_S$Kπ and η c (2S) → $K^0_S$Kπ decays are performed. A new measurement of the amplitude and phase of the Kπ S-wave as functions of the Kπ mass is performed, together with measurements of the $K^*_0$(1430), $K^*_0$(1950) and a 0 (1700) parameters. Finally, the branching fractions of χ c1 decays to K* resonances are also measured.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Transverse momentum dependent feed-down fractions for bottomonium production

We extract transverse-momentum-dependent feed-down fractions for bottomonium production using a data-driven approach. We use data published by the ATLAS, CMS, and LHCb Collaborations for √𝑠 =7 TeV proton-proton collisions. Based on this collected data, we produce fits to the differential cross sections for the production of both 𝑆- and 𝑃-wave bottomonium states. Combining these fits with branching ratios for excited state decays from the Particle Data Group, we compute the feed-down fractions for both the ϒ⁡(1⁢𝑆) and ϒ⁡(2⁢𝑆) as a function of transverse momentum. Our results indicate a strong dependence on transverse momentum, which is consistent with prior extractions of the feed-down fractions. When evaluated at the average momentum of the states, we find that approximately 75% of ϒ⁡(1⁢𝑆) and ϒ⁡(2⁢𝑆) states are produced directly. Our results for the transverse-momentum-dependent feed-down fractions are provided in tabulated form so that they can be used by other research groups.

Astronomy & Astrophysics↗
DOE OSTI2023

Observation of sizeable ω contribution to χ c 1 ( 3872 ) → π + π - J / ψ decays

Resonant structures in the dipion mass spectrum from $χ$ c1 (3872) → π + π - J/ψ decays, produced via B + → K + $χ$ c1 (3872) decays, are analyzed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb -1 . A sizeable contribution from the isospin conserving $χ$ c1 (3872) → ωJ/ψ decay is established for the first time, (21.4 ± 2.3 ± 2.0)%, with a significance of more than 7.1σ. The amplitude of isospin violating decay, $χ$ c1 (3872) → ρ 0 J/ψ, relative to isospin conserving decay, $χ$ c1 (3872) → ωJ/ψ, is properly determined, and it is a factor of 6 larger than expected for a pure charmonium state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Multidifferential study of identified charged hadron distributions in Z -tagged jets in proton-proton collisions at $\sqrt{s} =13$ TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a Z boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 < p T < 100 GeV and in the pseudorapidity range 2.5 < η <4. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb –1 . Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Forward neutrinos from charm at the Large Hadron Collider

The currently operating FASER experiment and the planned Forward Physics Facility (FPF) will detect a large number of neutrinos produced in proton-proton collisions at the LHC. In this work, we estimate neutrino fluxes at these detectors from charm meson decays, which will be particularly important for the ν e and ν τ channels. We make prediction using both the next-to-leading order collinear factorization and the k T -factorization approaches to model the production of charm quarks as well as different schemes to model their hadronization into charm hadrons. In particular, we emphasize that a sophisticated modeling of hadronization involving beam remnants is needed for predictions at FASER and FPF due to the sensitivity to the charm hadron production at low transverse momenta and very forward rapidity. As example, we use the string fragmentation approach implemented in 8. While both standard fragmentation functions and 8 are able to describe LHCb data, we find that 8 predicts significantly higher rate of high energy neutrinos, highlighting the importance of using the correct hadronization model when making predictions. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Bottomonium suppression in 5.02 and 8.16 TeV 𝑝-Pb collisions

Here, we compute the suppression of ϒ⁡(1⁢𝑆), ϒ⁡(2⁢𝑆), and ϒ⁡(3⁢𝑆) states in 𝑝-Pb collisions relative to 𝑝⁢𝑝 collisions, including nuclear parton distribution function (nPDF) effects, coherent energy loss, momentum broadening, and final-state interactions in the quark-gluon plasma. We employ the EPPS21 nPDFs and calculate the uncertainty resulting from variation over the associated error sets. To compute coherent energy loss and momentum broadening, we follow the approach of Arleo, Peigne, and collaborators. The 3+1⁢D viscous hydrodynamical background evolution of the quark-gluon plasma is generated by anisotropic hydrodynamics. The in-medium suppression of bottomonium in the quark-gluon plasma is computed using a next-to-leading-order open quantum system framework formulated within potential nonrelativistic quantum chromodynamics. We find that inclusion of all these effects provides a reasonable description of experimental data from the ALICE, ATLAS, CMS, and LHCb Collaborations for the suppression of ϒ⁡(1⁢𝑆), ϒ⁡(2⁢𝑆), and ϒ⁡(3⁢𝑆) as a function of both transverse momentum and rapidity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Reappraisal of SU(3)-flavor breaking in B → D P

In light of recently found deviations of the experimental data from predictions from QCD factorization for B ( s ) → D ( s ) P decays, where P = { π , K } , we systematically probe the current status of the SU ( 3 ) F expansion from a fit to experimental branching ratio data without any further theory input. We find that the current data are in agreement with the power counting of the SU ( 3 ) F expansion. While the SU ( 3 ) F limit is excluded at > 5 σ , amplitude-level SU ( 3 ) F -breaking contributions of ∼ 20 % suffice for an excellent description of the data. SU ( 3 ) F breaking is needed in tree ( > 5 σ ) and color-suppressed tree ( 2.4 σ ) diagrams. We are not yet sensitive to SU ( 3 ) F breaking in exchange diagrams. From the underlying SU ( 3 ) F parametrization we predict the unmeasured branching ratios B ( B ¯ s 0 → π − D + ) = 2 B ( B ¯ s 0 → π 0 D 0 ) = [ 0.3 , 7.2 ] × 10 − 6 of suppressed decays that can be searched for at the LHCb experiment. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

R K and future b → s ℓ ℓ physics beyond the standard model opportunities

Flavor changing neutral current |ΔB|=|ΔS|=1 processes are sensitive to possible new physics at the electroweak scale and beyond, providing detailed information about flavor, chirality and Lorentz structure. Recently the LHCb collaboration announced a 2.6σ deviation in the measurement of $R_K={\cal{B}}(\bar B \to \bar K \mu \mu)/{\cal{B}}(\bar B \to \bar K ee)$ from the standard model's prediction of lepton universality. We identify dimension six operators which could explain this deviation and study constraints from other measurements. Vector and axial-vector four-fermion operators with flavor structure $\bar s b \bar \ell \ell$ can provide a good description of the data. Tensor operators cannot describe the data. Pseudo-scalar and scalar operators only fit the data with some fine-tuning; they can be further probed with the $\bar B \to \bar K ee$ angular distribution. The data appears to point towards $C_9^{\rm NP \mu} = -C_{10}^{\rm NP \mu }<0$, an $SU(2)_{L}$ invariant direction in parameter space supported by R K , the $\bar B \to \bar K^* \mu \mu$ forward-backward asymmetry and the $\bar B_s \to \mu \mu$ branching ratio, which is currently allowed to be smaller than the standard model prediction. We present two leptoquark models which can explain the FCNC data and give predictions for the LHC and rare decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Formation of hidden-charm pentaquarks in photon-nucleon collisions

The cross section for formation in γ + ρ collisions of the recently found hidden-charm pentaquark states Ρ c (4380) and Ρ c (4450) is discussed and estimated. The studies of these resonances in photon beam experiments can be complementary to those in the LHCb experiment setting, and may be more advantageous for measurement of their additional decay channels. It is pointed out that both the relative importance of such decays and the yield of the resonances in the γ + ρ collisions are sensitive to the internal dynamics of the pentaquarks and can resolve between theoretical models. Specific numerical estimates are discussed within a simple ‘baryocharmonium’ model, where the the observed Ρ c resonances are composites of J/ψ and excited nucleon states with the quantum numbers of Ν(1440) and Ν(1520).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Search for the rare decays B 0 → J / ψ γ and B s 0 → J / ψ γ

A search for the rare decay of a B 0 or B$^{0}_{s}$ meson into the final state J/ψγ is performed, using data collected by the LHCb experiment in pp collisions at $\sqrt{s}$ = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb -1 . The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than 1.5×10 -6 for the B 0 →J/ψγ decay mode are excluded at 90% confidence level. For the B$^{0}_{s}$→J/ψγ decay mode, branching fraction values larger than 7.3×10 -6 are excluded at 90% confidence level; this is the first branching fraction limit for this decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Study of B – → D K – π + π – and B – → D π – π + π – decays and determination of the CKM angle γ

We report a study of the suppressed B¯ → DK – π + π – and favored B¯ → D π – π + π – decays, where the neutral D meson is detected through its decays to the K ∓ π ± and CP -even K + K – and π + π – final states. The measurement is carried out using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb –1 . We observe the first significant signals in the CP -even final states of the D meson for both the suppressed B ¯ → DK – π + π – and favored B ¯ → D π – π + π – modes, as well as in the doubly Cabibbo suppressed D → K + π – final state of the B ¯ → D π – π + π – decay. Evidence for the suppressed decay B ¯ → DK – π + π – , with D → K + π – , is also presented. From the observed yields in the B ¯→ DK – π + π – , B ¯ → D π – π + π – and their charge conjugate decay modes, the most probable value of the weak phase γ corresponds to γ = (74 +20 –19 )°. This is one of the most precise single-measurement determinations of γ to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Model-independent confirmation of the Z ( 4430 ) - state

Here, the decay B 0 →ψ(2S)K + π - is analyzed using 3 fb -1 of pp collision data collected with the LHCb detector. A model-independent description of the ψ(2S)π mass spectrum is obtained, using as input the Kπ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the ψ(2S)π mass spectrum can be described in terms of Kπ reflections alone is rejected with more than 8σ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430) - exotic state.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

First observation of the rare B + → D + K + π - decay

The B + → D + K + π - decay is observed in a data sample corresponding to 3.0 fb -1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. The signal significance is 8σ and the branching fraction is measured to be B(B + →D + K + π - )=(5.31±0.90±0.48±0.35)×10 -6 , where the uncertainties are statistical, systematic and due to the normalization mode B + → D - K + π + , respectively. The Dalitz plot appears to be dominated by broad structures. Angular distributions are exploited to search for quasi-two-body contributions from B + → D$ ^&lowast;_2 $(2460) 0 K + and B + → D + K &lowast; (892) 0 decays. No significant signals are observed and upper limits are set on their branching fractions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Studies of the resonance structure in D 0 → K S 0 K ± π ∓ decays

Amplitude models are applied to studies of resonance structure in D 0 → K 0 S K – π + and D 0 → K 0 S K + π – decays using pp collision data corresponding to an integrated luminosity of 3.0 fb –1 collected by the LHCb experiment. Relative magnitude and phase information is determined, and coherence factors and related observables are computed for both the whole phase space and a restricted region of 100 MeV/c 2 around the K *(892) ± resonance. Two formulations for the K π S -wave are used, both of which give a good description of the data. The ratio of branching fractions B( D 0 → K 0 S K + π – )/B( D 0 → K 0 S K – π + ) is measured to be 0.655±0.004(stat)±0.006(syst) over the full phase space and 0.370 ± 0.003 (stat) ± 0.012 (syst) in the restricted region. A search for CP violation is performed using the amplitude models and no significant effect is found. Predictions from SU(3) flavor symmetry for K *(892) K amplitudes of different charges are compared with the amplitude model results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the B s 0 → D s ( * ) + D s ( * ) – branching fractions

The branching fraction of the decay B 0 s → D (*) + s D (*) – s is measured using pp collision data corresponding to an integrated luminosity of 1.0 fb –1 , collected using the LHCb detector at a center-of-mass energy of 7 TeV. It is found to be B(B 0 s → D (*) s + D s (*) – ) = (3.05 ± 0.10 ± 0.20 ± 0.34)%, where the uncertainties are statistical, systematic, and due to the normalization channel, respectively. The branching fractions of the individual decays corresponding to the presence of one or two D* ± s are also measured. The individual branching fractions are found to be B(B 0 s → D* ± s D ∓ s ) = (1.35 ± 0.06 ± 0.09 ± 0.15)%, B(B 0 s → D* + s D* – s ) = (1.27 ± 0.08 ± 0.10 ± 0.14)%. All three results are the most precise determinations to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Constraints on the unitarity triangle angle γ from Dalitz plot analysis of B 0 → D K + π – decays

The first study is presented of CP violation with an amplitude analysis of the Dalitz plot of B 0 → DK + π – decays, with D → K + π – , K + K – , and π + π – . The analysis is based on a data sample corresponding to 3.0 fb –1 of pp collisions collected with the LHCb detector. No significant CP violation effect is seen, and constraints are placed on the angle γ of the unitarity triangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the B 0 → DK *(892) 0 decay are determined for the first time. These measurements can be used to improve the sensitivity to γ of existing and future studies of the B 0 → DK *(892) 0 decay.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗