Engineering topics

Carniti, P.

Publications and source records attributed to Carniti, P..

66 records · Page 4

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

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

Observation of the B$^{0}_{s}$ → J/ψφφ decay

The B$^{0}_{s}$ → J/ψφφ decay is observed in pp collision data corresponding to an integrated luminosity of 3 fb –1 recorded by the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV. This is the first observation of this decay channel, with a statistical significance of 15 standard deviations. The mass of the B$^{0}_{s}$ meson is measured to be 5367.08 ± 0.38 ± 0.15 MeV/c 2 . The branching fraction ratio $\mathscr{B}$(B$^{0}_{s}$ → J/ψφφ)/$\mathscr{B}$(B$^{0}_{s}$ → J/ψφ) is measured to be 0.0115 ± 0.0012 – 0.0009 + 0.0005 . In both cases, the first uncertainty is statistical and the second is systematic. No evidence for non-resonant B$^{0}_{s}$ → J/ψφK+K– or B$^{0}_{s}$ → J/ψK+K–K+K– decays is found.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Study of D$^{sJ}_{()+}$ mesons decaying to D + K$_{0}^{S}$ and D *0 K + final states

A search is performed for D$^{sJ}_{(*)+}$ mesons in the reactions pp → D *+ K$_{0}^{S}$X and pp → D *0 K + X using data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb detector. For the D * + K$_{0}^{S}$ final state, the decays D *+ → D 0 π + with D 0 → K - π + and D 0 → K - π + π + π - are used. For D *0 K + , the decay D *0 → D 0 π 0 with D 0 → K - π + is used. A prominent D s1 (2536) + signal is observed in both D* +K$_{0}^{S}$ and D* 0 K + final states. The resonances D $^{s1}_{*}$ (2700) + and D $^{s3}_{*}$ (2860) + are also observed, yielding information on their properties, including spin-parity assignments. The decay D $^{s2}_{*}$ (2573) + → D* + K$_{0}^{S}$ is observed for the first time, at a significance of 6.9 σ, and its branching fraction relative to the D $^{s2}_{*}$ (2573) + → D + K$_{0}^{S}$ decay mode is measured.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2016

Angular analysis of the B o → K *o μ + μ – decay using 3 fb –1 of integrated luminosity

An angular analysis of the B o → K *o (→ K + π – )μ + μ – decay is presented. The dataset corresponds to an integrated luminosity of 3.0 fb –1 of pp collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine CP-averaged observables and CP asymmetries, taking account of possible contamination from decays with the K + π – system in an S-wave configuration. The angular observables and their correlations are reported in bins of q 2 , the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for q 2 -dependent decay amplitudes in the region 1.1 < q 2 < 6.0 GeV 2 /c 4 , the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of CP-averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions.

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↗

DOE OSTI2016

Study of the production of Λ$0\atop{b}$ and $\bar{B}$ 0 hadrons in pp collisions and first measurement of the Λ$0\atop{b}$ → J/ΨpK¯ branching fraction

The product of the Λ$0\atop{b}$ ($\bar{B}$ 0 ) differential production cross-section and the branching fraction of the decay Λ$0\atop{b}$ → J/Ψp$\bar{K}$ ($\bar{B}$ 0 → J/Ψ$\bar{K}$*(892) 0 ) is measured as a function of the beauty hadron transverse momentum, p T , and rapidity, y. The kinematic region of the measurements is p T < 20 GeV/c and 2.0 < y < 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3fb –1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s = 7 TeV in 2011 and √s = 8 TeV in 2012.

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

Measurement of CP violation parameters and polarisation fractions in $ {\mathrm{B}}_{\mathrm{s}}^0\to \mathrm{J}/\psi {\overline{\mathrm{K}}}^{\ast 0}$ decays

The first measurement of CP asymmetries in the decay ${B}_s^0\to J/\psi {\overline{\mathrm{K}}}^{\ast }{(892)}^0$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb -1 of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Together with constraints from B $^o$ → J/$ψ$ $ρ$ $^o$, the results are used to constrain additional contributions due to penguin diagrams in the CP -violating phase $\phi_s$, measured through $B_s$ $^o$ decays to charmonium.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

First neutrinoless double beta decay results from CUORE-0

The CUORE-0 experiment, a 52 bolometer array searching for neutrinoless double beta decay from {sup 130}Te, has started taking data in spring 2013 underground at the Laboratori Nazionali del Gran Sasso (LNGS). The excellent results obtained in terms of energy resolution and background level allowed this experiment to reach the sensitivity of Cuoricino in approximately half the runtime. Combining CUORE-0 data (9.8 kg·yr exposure of {sup 130}Te) with the 19.75 kg·yr exposure of the Cuoricino experiment, we obtain the most stringent limit to date on the half-life of this isotope (T{sub 1/2} > 4.0 × 10{sup 24} yr). In this article, we review the results from CUORE-0 and discuss the status and the physics potential of CUORE, a 19 times larger bolometer array that plans to begin operations by end of this year.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2015

Measurement of the branching fraction ratio B ( B c + → ψ ( 2 S ) π + ) / B ( B c + → J / ψ π + )

Using pp collision data collected by LHCb at center-of-mass energies $\sqrt{s}$ = 7 TeV and 8 TeV, corresponding to an integrated luminosity of 3 fb -1 , the ratio of the branching fraction of the B$^{+}_{c}$→ψ(2S)π+ decay relative to that of the B$^{+}_{c}$→J/ψπ+ decay is measured to be 0.268±0.032(stat)±0.007(syst)±0.006(BF). The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainties on the branching fractions of the J/ψ→μ+μ- and ψ(2S)→μ+μ- decays. This measurement is consistent with the previous LHCb result, and the statistical uncertainty is halved.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2015

Search for Hidden-Sector Bosons in B 0 → K * 0 μ + μ – Decays

A search is presented for hidden-sector bosons, χ, produced in the decay B 0 →K*(892) 0 χ, with K*(892) 0 →K + π - and χ→μ + μ - . The search is performed using pp-collision data corresponding to 3.0fb -1 collected with the LHCb detector. No significant signal is observed in the accessible mass range 214 ≤m (χ) ≤ 4350 MeV, and upper limits are placed on the branching fraction product $\mathscr{B}$(B 0 →K*(892) 0 χ) × $\mathscr{B}$(χ→μ + μ - ) as a function of the mass and lifetime of the χ boson. These limits are of the order of 10 -9 for χ lifetimes less than 100 ps over most of the m(χ) range, and place the most stringent constraints to date on many theories that predict the existence of additional low-mass bosons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗