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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Observation of the Open-Charm Tetraquark Candidate T c s 0 * ( 2870 ) 0 in the B − → D − D 0 K S 0 Decay

An amplitude analysis of B − → D − D 0 K S 0 decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9 fb − 1 , collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A resonant structure of spin-parity 0 + is observed in the D 0 K S 0 invariant-mass spectrum with a significance of 5.3 σ . The mass and width of the state, modeled with a Breit-Wigner line shape, are determined to be 2883 ± 11 ± 8 MeV / c 2 and 87 − 47 + 22 ± 17 MeV , respectively, where the first uncertainties are statistical and the second systematic. These properties and the quark content are consistent with those of the open-charm tetraquark candidate T c s 0 * ( 2870 ) 0 observed previously in the D + K − final state of the B − → D − D + K − decay. This result confirms the existence of the T c s 0 * ( 2870 ) 0 state in a new decay mode. The T c s 1 * ( 2900 ) 0 state, reported in the B − → D − D + K − decay, is also searched for in the D 0 K S 0 invariant-mass spectrum of the B − → D − D 0 K S 0 decay, without finding evidence for it. © 2025 CERN, for the LHCb Collaboration 2025 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2025

Test of Lepton Flavor Universality with B s 0 → ϕ ℓ + ℓ − Decays

Lepton flavor universality in rare b → s transitions is tested for the first time using B s 0 meson decays. The measurements are performed using p p collision data collected by the LHCb experiment between 2011 and 2018, corresponding to a total integrated luminosity of 9 fb − 1 . Branching fraction ratios between the B s 0 → ϕ e + e − and B s 0 → ϕ μ + μ − decays are measured in three regions of dilepton mass squared, q 2 , with 0.1 < q 2 < 1.1 , 1.1 < q 2 < 6.0 , and 15 < q 2 < 19 GeV 2 / c 4 . The results agree with the standard model expectation of lepton flavor universality. © 2025 CERN, for the LHCb Collaboration 2025 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2025

Test of Lepton Flavor Universality with B + → K + π + π − ℓ + ℓ − Decays

The first test of lepton flavor universality between muons and electrons using B + → K + π + π − ℓ + ℓ − ( ℓ = e , μ ) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb − 1 . The ratio of branching fractions between B + → K + π + π − e + e − and B + → K + π + π − μ + μ − decays is measured in the dilepton invariant-mass-squared range 1.1 < q 2 < 7.0 GeV 2 / c 4 and is found to be R K π π − 1 = 1.3 1 − 0.17 + 0.18 ( stat ) − 0.09 + 0.12 ( syst ) , in agreement with the standard model prediction. The first observation of the B + → K + π + π − e + e − decay is also reported. © 2025 CERN, for the LHCb Collaboration 2025 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2016

Open charm production in double parton scattering processes in the forward kinematics

We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment.We find that the mean field approximation for the double partonGPD (generalized parton distributions), which neglects parton–parton correlations, underestimates the rate by a factor of 2. The enhancement due to the perturbative QCD correlation 1Ⓧ2 mechanism which explains the rate of double parton interactions at the central rapidities is found to explain 60 ÷ 80% of the discrepancy. We argue that the nonperturbative fluctuations leading to nonfactorized (correlated) contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, the two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the σeff (i.e. the ratio of double and square of single inclusive rates) in the discussed kinematics as a function of pt . The account for two correlation mechanisms strongly reduces the sensitivity of the results to the starting point of the QCD evolution.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

A study of $CP$ violation in the decays $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$ ($h$ = $K, π$) and $B^±$ → [$π^+π^-π^+π^-$]$_Dh^±$

The first study of CP violation in the decay mode $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$, with $h$ = $K, π$, is presented, exploiting a data sample of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9 fb -1 . The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP-violating observables that are sensitive to the angle γ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$ and $B^±$ → [$π^+π^-π^+π^-$]$_Dh^±$ decays.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Measurement of $\tau _\text {L}$ using the ${B} _s^0 \rightarrow J/\psi \eta$ decay mode

Using a proton–proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of $5.7~\text {fb}^{-1}$ , the lifetime of the light ${{B} ^0_{s}}$ mass eigenstate, $\tau _{L}$ , is measured using the $B^0_s \rightarrow J/\psi \eta$ decay mode to be $\begin{aligned} \tau _{\text {L}} = 1.445 \pm 0.016 \text {(stat)} \pm 0.008 \text {(syst)} \,\text {ps}. \end{aligned}$ A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb –1 of integrated luminosity gives $\begin{aligned} \tau _{\text {L}} = 1.452 \pm 0.014 \pm 0.007 \pm 0.002 \,\text {ps}, \end{aligned}$ where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Open charm production and asymmetry in p Ne collisions at $\sqrt{s_{\scriptscriptstyle {\textrm{NN}}}}$ = 68.5 GeV

A measurement of D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D 0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $\sqrt{s_{NN}}$ = 68.5 GeV. The sum of the D 0 and $\overline{D}$ 0 production cross-section in pNe collisions in the centre-of-mass rapidity range y* ϵ [-2.29,0] is found to be $σ^{y* ϵ [-2.29,0]}_{D^0}$ = 48.2 ± 0.3 ± 4.5 μb/nucleon where the first uncertainty is statistical and the second is systematic. The D 0 and $\overline{D}$ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative y*. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

First Beam Test of UT Sensors with the SALT 3.0 Readout ASIC

This note presents the results of a beam test conducted at the Fermilab test beam facility in March 2019. The beam test represents the first such test of the UT readout ASIC, SALT 3.0, in a beam with production UT sensors. Two sensors were tested, one an unirradiated p-in-n sensor, and the second a n-in-p sensor irradiated to twice the maximum expected uence. The beam test demonstrates that the SALT 3.0 ASIC meets our specifications, and can be used for the production. Due to specific issues with the data acquisition system that will not be present in the system in LHCb, a higher threshold was used in the beam test, corresponding to about $6 \sigma$ on the noise. With this higher threshold, the signal-to-noise ratio (S/N) and efficiency are measured. For the unirradiated sensor, a S/N of about 12 is achieved, with a single-hit effciency of at least 99.5%. For the irradiated sensor, a S/N of about 11 is obtained, with a single-hit effciency of about 94%. In the final system in LHCb with a proper threshold of about $3-4 \sigma$ of the noise, we expect to achieve a single-hit effciency of at least 99.5%.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Inclusive production of the $P_c$ resonances in $p \overline p $ collisions

We present a study of the inclusive production in $p \overline p $ collisions of the pentaquark states $P_c(4440)$ and $P_c(4457)$ with the decay to the $J/\psi p$ final state previously observed by the LHCb experiment. Using a sample of candidates originating from decays of $b$-flavored hadrons, we find an enhancement in the $J/\psi p$ invariant mass distribution consistent with a sum of $P_c(4440)$ and $P_c(4457)$. The significance, with the input parameters set to the LHCb values, is $3.0\sigma$. This is the first confirmatory evidence for these pentaquark states. We measure the ratio $N_{\rm prompt}/N_{\rm nonprompt}=0.05 \pm 0.39$ and set an upper limit of 0.8 at the 95\% credibility level. The ratio of the yield of the $P_c(4312)$ to the sum of $P_c(4440)$ and $P_c(4457)$ is less than 0.6 at the 95\% credibility level. The study is based on $10.4~\rm{fb^{-1}}$ of data collected by the D0 experiment at the Fermilab Tevatron collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Observation of Enhanced Double Parton Scattering in Proton-Lead Collisions at $\sqrt{s_{NN}}$= 8.16 TeV

A study of prompt charm-hadron pair production in proton-lead collisions at $\sqrt{s_{NN}$ = 8.16 TeV is performed using data corresponding to an integrated luminosity of about 30 nb -1 , collected with the LHCb experiment. Production cross sections for different pairs of charm hadrons are measured and kinematic correlations between the two charm hadrons are investigated. This is the first measurement of associated production of two charm hadrons in proton-lead collisions. The results confirm the predicted enhancement of double parton scattering production in proton-lead collisions compared to the single parton scattering production.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

X(3872): Status and prospects

The most recent experimental results obtained by studying the X(3872) state in the CLEO-c, LHCb, and BESIII experiments are surveyed, and prospects of its further studies are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Z{sup +}(4430): Nonexotic interpretation

The possibility of describing the charged charmonium-like state Z{sup +}(4430) as the kinematical rescattering effect is examined. This approach makes it possible to avoid the introduction of exotic hadron states in the model, and one describes structures in the ψ(2S)π{sup +} mass spectrum by the presence of the D{sub s}{sup (*)′} resonance in a hidden intermediate state. The resulting model predictions are compared with the results obtained by the LHCb Collaboration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Manifestation of Nonuniversality of Lepton Interactions in Spontaneously Violated Mirror Symmetry

Data from the LHCb experiments are indicative of a substantial distinction between the B → K (or K*) + e{sup +}e{sup −} and B → K (or K*) + μ{sup +}μ{sup −} branching ratios (April 2017). The branching ratio for the e+e− channel is substantially greater than that for the μ{sup +}μ{sup −} channel, whereas Standard Model (SM) calculations require that they be equal to each other. The above distinction may suggest the existence of a new interaction changing generations and discriminating between leptons that has couplings that are much greater than and are inverse in strength to the SM fermion couplings to the Higgs boson. Under conditions of spontaneously violated mirror symmetry, the coupling of SM particles to the second Higgs scalar that is inevitably present there and which is in principle heavy possesses precisely these properties. An inverse character of this coupling and its strength are not an additional hypothesis but a necessary condition for qualitatively reproducing, in addition, the observed charged-lepton mass hierarchy and the structure of weak lepton mixing—the Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix. Within the mirror model being considered, all properties of the new interaction, including its inverse character, are due to the hierarchical character of the quark and charged-lepton mass spectrum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Quark–Diquark Structure and Masses of Doubly Charmed Baryons

finite size of a doubly heavy diquark yields a positive correction to baryon masses calculated in the local-diquark approximation. Upon evaluating this correction for the ground states of doubly charmed baryons, it became possible to obtain new predictions of importance for current searches of these baryons in LHCb experiments: m[Ξ{sub cc}{sup 1/2{sup +{sup +}}}]≈m[Ξ{sub cc}{sup 1/2{sup +{sup +}}}] = 3615 ± 55 MeV and m[Ξ{sub cc}{sup 3/2{sup +{sup +}}}]≈m[Ξ{sub cc}{sup 3/2{sup +{sup +}}}] 3747 ± 55 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Modification of Χ c1 (3872) and ψ(2S) Production in p Pb Collisions at $\sqrt{S_{NN}}$ = 8.16 TeV

The LHCb Collaboration measures production of the exotic hadron Χ c1 (3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state ψ(2S) suggests that the exotic Χ c1 (3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify Χ c1 (3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

The LHC Experiments

The Large Hadron Collider or LHC is the world’s biggest particle accelerator, but it can only get particles moving very quickly. To make measurements, scientists must employ particle detectors. There are four big detectors at the LHC: ALICE, ATLAS, CMS, and LHCb. In this video, Fermilab’s Dr. Don Lincoln introduces us to these detectors and gives us an idea of each one’s capabilities.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Measurement of the ratio of the production cross sections times branching fractions of $B_{c}^{\pm} \to J/\psi \pi^{\pm}$ and $B^{\pm} \to J/\psi K^{\pm}$ and $\mathcal{B}(B_{c}^{\pm} \to J/\psi \pi^{\pm}\pi^{\pm}\pi^{\mp})/\mathcal{B}(B_{c}^{\pm} \to J/\psi \pi^{\pm})$ in pp collisions at $\sqrt{s} =$ 7 TeV

The ratio of the production cross sections times branching fractions (σ(B ± c )B(B ± c →J/ψπ ± ))/(σ(B ± )B(B ± →J/ψK ± )) is studied in proton-proton collisions at a center of-mass energy of 7 TeV with the CMS detector at the LHC. The kinematic region investigated requires B c ± and B ± mesons with transverse momentum p T > 15 GeV and rapidity |y|< 1.6. The data sample corresponds to an integrated luminosity of 5.1 fb -1 . The ratio is determined to be [0.48±0.05(stat)± 0.03(syst)±0.05 (τBc)]%. The B c ± → J/ψπ ± π ± π ∓ decay is also observed in the same data sample. Using a model-independent method developed to measure the efficiency given the presence of resonant behaviour in the three-pion system, the ratio of the branching fractions B(B ± c →J/ψπ ± π ± π ∓ )/B(B ± c →J/ψπ ± ) is measured to be 2.55±0.80(stat)±0.33(syst) +0.04 -0.01 (τ Bc ), consistent with the previous LHCb result.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of forward W and Z boson production in pp collisions at $\sqrt{s}=8$ TeV

Measurements are presented of electroweak boson production using data from pp collisions at a centre-of-mass energy of $\sqrt{s}=8$ TeV. The analysis is based on an integrated luminosity of 2.0 fb –1 recorded with the LHCb detector. The bosons are identified in the W → μν and Z → μ + μ – decay channels. The cross-sections are measured for muons in the pseudorapidity range 2.0 < η < 4.5, with transverse momenta p T >20 GeV/c and, in the case of the Z boson, a dimuon mass within 60 < M$_{μ^{+}μ–}$ < 120 GeV/c. The results are σ$_{W^{+}→μ^{+}ν}$ = 1093.6 ± 2.1 ± 7.2 ± 10.9 ± 12.7 pb, σ$_{W^{–}→μ^{–}\bar{ν}}$ = 818.4 ± 1.9 ± 5.0 ± 7.0 ± 9.5 pb, σ$_{Z→μ^{+}μ–}$ = 95.0 ± 0.3 ± 0.7 ± 1.1 ± 1.1 pb, where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. The evolution of the W and Z boson cross-sections with centre-of-mass energy is studied using previously reported measurements with 1.0 fb –1 of data at 7 TeV. Differential distributions are also presented. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗