Search for contact interactions and large extra dimensions in dilepton events from pp collisions at root s=7 TeV with the ATLAS detector
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Measurement of the inclusive semileptonic branching fraction B ( B s 0 → X - ℓ + ν ℓ ) at Belle
Here, we report a measurement of the inclusive semileptonic B s 0 branching fraction in a 121 fb - 1 data sample collected near the Υ ( 5 S ) resonance with the Belle detector at the KEKB asymmetric energy e + e - collider. Events with B s 0 ( * ) B ¯ s 0 ( * ) pairs are selected by reconstructing a tag side D s + and identifying a signal side lepton ℓ + ( ℓ = e , μ ) that is required to have the same-sign charge to ensure that both originate from different B s 0 mesons. The B s 0 → X - ℓ + ν ℓ branching fraction is extracted from the ratio of the measured yields of D s + mesons and D s + ℓ + pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be [ 10.6 ± 0.5 ( stat ) ± 0.7 ( syst ) ] % .
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
First observation of the Z b 0 ( 10610 ) in a Dalitz analysis of Υ ( 10860 ) → Υ ( n S ) π 0 π 0
Here, we report the first observation of Υ ( 10860 ) → Υ ( 1 , 2 , 3 S ) π 0 π 0 decays. The neutral partner of the Z b ± ( 10610 ) , the Z b 0 ( 10610 ) decaying to Υ ( 2 , 3 S ) π 0 , is observed for the first time with a 6.5 σ significance using a Dalitz analysis of Υ ( 10860 ) → Υ ( 2 , 3 S ) π 0 π 0 decays. The findings are obtained with a 121.4 fb - 1 data sample collected with the Belle detector at the Υ ( 10860 ) resonance at the KEKB asymmetric-energy e + e - collider.
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Measurement of the decays B s 0 → J / ψ Φ ( 1020 ) , B s 0 → J / ψ f 2 ' ( 1525 ) and B s 0 → J / ψ K + K – at Belle
In this paper, we report a measurement of the branching fraction of the decay B s 0 → J / ψ Φ ( 1020 ) , evidence and a branching fraction measurement for B s 0 → J / ψ f 2 ' ( 1525 ) , and the determination of the total B s 0 → J / ψ K + K – branching fraction, including the resonant and non-resonant contributions to the K+K– channel. We also determine the S-wave contribution within the Φ(1020) mass region. The absolute branching fractions are B[ B s 0 → J / ψ Φ ( 1020 ) ] = (1.25 ± 0.07(stat) ± 0.08(syst) ± 0.22(fs)) × 10 –3 , B[ B s 0 → J / ψ f 2 ' ( 1525 ) ] = (0.26 ± 0.06(stat) ± 0.02(syst) ± 0.05(fs)) × 10 –3 and B[ B s 0 → J / ψ K + K – ] = (1.01 ± 0.09(stat) ± 0.10(syst) ± 0.18(fs)) × 10 –3 , where the last systematic error is due to the branching fraction of bb¯→ B$^{(*)}_{s}$B$^{(*)}_{s}$. The branching fraction ratio is found to be B[ B s 0 → J / ψ f 2 ' ( 1525 ) ]/B[ B s 0 → J / ψ Φ ( 1020 ) ] = (21.5 ± 4.9(stat) ± 2.6(syst)). All results are based on a 121.4 fb –1 data sample collected at the Υ(5S) resonance by the Belle experiment at the KEKB asymmetric-energy e + e – collider.
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Observation of a new charged charmoniumlike state in B ¯ 0 → J / ψ K – π + decays
We present the results of an amplitude analysis of B¯ 0 → J/ψK – π + decays. A new charged charmoniumlike state Z c (4200) + decaying to J/ψπ + is observed with a significance of 6.2σ. The mass and width of the Z c (4200) + are 4196$^{+31+17}_{–29–13}$ MeV/c 2 and 370$^{+70+70}_{–70–132}$ MeV, respectively; the preferred assignment of the quantum numbers is J P = 1 + . In addition, we find evidence for Z c (4430) + → J/ψπ + . In conclusion, the analysis is based on a 711 fb –1 data sample collected by the Belle detector at the asymmetric-energy e + e – collider KEKB.
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Amplitude analysis of e + e - →Υ(nS)π + π - at $\sqrt{s}$ = 10.886 GeV
Here, we report results on studies of the e + e - annihilation into three-body Υ ( n S ) π + π - ( n = 1 , 2 , 3 ) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at s = 10.866 GeV and corrected for the initial state radiation are σ ( e + e - → Υ ( 1 S ) π + π - ) = ( 2.27 ± 0.12 ± 0.14 ) pb , σ ( e + e - → Υ ( 2 S ) π + π - ) = ( 4.07 ± 0.16 ± 0.45 ) pb , and σ ( e + e - → Υ ( 3 S ) π + π - ) = ( 1.46 ± 0.09 ± 0.16 ) pb . Amplitude analysis of the three-body Υ ( n S ) π + π - final states strongly favors I G ( J P ) = 1 + ( 1 + ) quantum-number assignments for the two bottomonium-like Z b ± states, recently observed in the Υ ( n S ) π ± and h b ( m P ) π ± ( m = 1 , 2 ) decay channels. The results are obtained with a 121.4 fb - 1 data sample collected with the Belle detector at the KEKB asymmetric-energy e + e - collider.
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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.
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Studies of charmed strange baryons in the Λ D final state at Belle
In this report, we discuss the discovery of Ξ c ( 3055 ) 0 , observed by its decay into the final-state Λ D 0 , and present the first observation and evidence of the decays of Ξ c ( 3055 ) + and Ξ c ( 3080 ) + into Λ D + . Furthermore, we perform a combined analysis of the Λ D + with the Σ c + + K - and Σ c * + + K - decay modes to measure the ratios of branching fractions, masses and widths with improved accuracy. We measure the ratios of branching fractions B ( Ξ c ( 3055 ) + → Λ D + ) / B ( Ξ c ( 3055 ) + → Σ c + + K - ) = 5.09 ± 1.01 ± 0.76 , B ( Ξ c ( 3080 ) + → Λ D + ) / B ( Ξ c ( 3080 ) + → Σ c + + K - ) = 1.29 ± 0.30 ± 0.15 , and B ( Ξ c ( 3080 ) + → Σ c * + + K - ) / B ( Ξ c ( 3080 ) + → Σ c + + K - ) = 1.07 ± 0.27 ± 0.04 , where the uncertainties are statistical and systematic. The analysis is performed using a 980 fb - 1 data sample collected with the Belle detector at the KEKB asymmetric-energy e + e - collider.
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Observation of an alternative χ c 0 ( 2 P ) candidate in e + e - → J / ψ D D ¯
IN this work, we perform a full amplitude analysis of the process e + e - → J / ψ D D ¯ , where D refers to either D 0 or D + . A new charmoniumlike state X * ( 3860 ) that decays to D D ¯ is determined with a significance of 6.5 σ . Its mass is ( 3862 - 32 + 26 - 13 + 40 ) MeV / c 2 , and its width is ( 201 - 67 + 154 - 82 + 88 ) MeV . The J P C = 0 + + hypothesis is favored over the 2 + + hypothesis at the level of 2.5 σ . The analysis is based on the 980 fb - 1 data sample collected by the Belle detector at the asymmetric-energy e + e - collider KEKB.
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Observation of the helicity-selection-rule suppressed decay of the χ c 2 charmonium state
The decays of χ c 2 → K + K - π 0 , K S K ± π ∓ , and π + π - π 0 are studied with the ψ ( 3686 ) data samples collected with the Beijing Spectrometer (BESIII). For the first time, the branching fractions of χ c 2 → K*$\bar{K}$ , χ c 2 → $a_2^±$(1320)π ∓ /$a_2^0$(1320)π 0 , and χ c 2 → ρ( 770 ) ± π ∓ are measured. Here, K*$\bar{K}$ denotes both K* ± K ∓ and its isospin-conjugated process K* 0 $\bar{K}$ 0 +c.c., and K* denotes the resonances K*(892), $K_2^*$(1430), and $K_3^*$(1780). The observations indicate a strong violation of the helicity selection rule in χ c 2 decays into vector and pseudoscalar meson pairs. The measured branching fractions of χ c 2 → K*(892)$\bar{K}$ are more than ten times larger than the upper limit of χ c 2 → ρ ( 770 ) ± π ∓ , which is so far the first direct observation of a significant U -spin symmetry breaking effect in charmonium decays.
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Measurement of the decays Λ c → Σ π π at Belle
We report measurements of the branching fractions of the decays Λ c + → Σ + π - π + , Λ c + → Σ 0 π + π 0 and Λ c + → Σ + π 0 π 0 relative to the reference channel Λ c + → p K - π + . The analysis is based on the full data sample collected at and near the Υ ( 4 S ) resonance by the Belle detector at the KEKB asymmetric-energy e + e - collider, corresponding to an integrated luminosity of 711 fb - 1 . We measure B ( Λ c + → Σ + π - π + ) / B ( Λ c + → p K - π + ) = 0.7 19 ± 0.003 ± 0.02 4 , B ( Λ c + → Σ 0 π + π 0 ) / B ( Λ c + → p K - π + ) = 0. 575 ± 0.005 ± 0.0 36 and B ( Λ c + → Σ + π 0 π 0 ) / B ( Λ c + → p K - π + ) = 0. 247 ± 0.006 ± 0.01 9 . The listed uncertainties are statistical and systematic, respectively.
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First Observation of the P-Wave Spin-Singlet Bottomonium States h b (1P) and h b (2P)
Not Available
Adachi, I.↗
Observation of Two Charged Bottomoniumlike Resonances in Υ ( 5 S ) Decays
We report the observation of two narrow structures in the mass spectra of the π±Υ(nS) (n=1, 2, 3) and π±hb(mP) (m=1, 2) pairs that are produced in association with a single charged pion in Υ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M1=(10 607.2±2.0) MeV/c 2 , Γ 1 =(18.4±2.4) MeV, and M 2 =(10 652.2±1.5) MeV/c 2 , Γ 2 =(11.5±2.2) MeV. The results are obtained with a 121.4 fb -1 data sample collected with the Belle detector in the vicinity of the Υ(5S) resonance at the KEKB asymmetric-energy e+e- collider.
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Observation of New Resonant Structures in γ γ → ω Φ , Φ Φ , and ω ω
The processes γγ --> ωΦ, ΦΦ, and ωω are measured using an 870 fb -1 data sample collected with the Belle detector at the KEKB asymmetric-energy e + e - collider. Production of vector meson pairs is clearly observed and their cross sections are measured for masses that range from threshold to 4.0 GeV. In addition to signals from well established spin-zero and spin-two charmonium states, there are resonant structures below charmonium threshold, which have not been previously observed. We report a spin-parity analysis for the new structures and determine the products of the η c , χ c0 , and χ c2 two-photon decay widths and branching fractions to ωΦ, ΦΦ, and ωω.
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Combined Search for the Standard Model Higgs Boson Decaying to bb̄ Using the D0 Run II Data Set
We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into bb̄ using the data sample collected with the D0 detector in pp̄ collisions at √s=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% C.L. upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV≤M H ≤150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% C.L. In the mass range 120 GeV≤M H ≤145 GeV, the data exhibit an excess above the background prediction with a global significance of 1.5 standard deviations, consistent with the expectation in the presence of a standard model Higgs boson.
Abazov, V. M.↗
Study of e + e - → π + π - J / ψ and Observation of a Charged Charmoniumlike State at Belle
The cross section for $e^+e^-→π^+π^-J/ψ$ between 3.8 GeV and 5.5 GeV is measured with a 967 fb -1 data sample collected by the Belle detector at or near the $\Upsilon(nS)$ ($n=1, 2, ..., 5$) resonances. The $\Upsilon$(4260) state is observed, and its resonance parameters are determined. In addition, an excess of $π^+π^-J/ψ$ production around 4 GeV is observed. This feature can be described by a Breit-Wigner parameterization with properties that are consistent with the $\Upsilon$(4008) state that was previously reported by Belle. In a study of $\Upsilon$(4260)→$π^+π^-J/ψ$ decays, a structure is observed in the $M(\pi^{\pm}J/ψ)$ mass spectrum with 5.2$σ$ significance, with mass M=(3894.5±6.6±4.5)MeV/$c^2$ and width $Γ$=(63±24±26) MeV/$c^2$, where the errors are statistical and systematic, respectively. This structure can be interpreted as a new charged charmonium-like state.
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Measurement of prompt ψ ( 2 S ) to J / ψ yield ratios in Pb-Pb and p - p collisions at s N N = 2.76 TeV
The ratio between the prompt ψ(2S) and J/ψ yields, reconstructed via their decays into μ⁺μ⁻, is measured in Pb-Pb and p-p collisions at √ s NN = 2.76 TeV. The analysis is based on Pb-Pb and p-p data samples collected by CMS at the Large Hadron Collider, corresponding to integrated luminosities of 150 μb⁻¹ and 5.4 pb⁻¹, respectively. The double ratio of measured yields (N ψ(2S) /N J/ψ ) Pb−Pb /(N ψ(2S) /N J/ψ ) p−p is computed in three Pb-Pb collision centrality bins and two kinematic ranges: one at midrapidity, |y| < 1.6, covering the transverse momentum range 6.5 < p T < 30 GeV/c, and the other at forward rapidity, 1.6<|y|<2.4, extending to lower pT values, 3<pT<30 GeV/c. The centrality-integrated double ratio changes from 0.45 ± 0.13 (stat) ± 0.07 (syst) in the first range to 1.67 ± 0.34 (stat) ± 0.27 (syst) in the second. This difference is most pronounced in the most central collisions.
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