62,945 research outputs found
1ST MEASUREMENT OF GAMMA(D(S)(+)-]MU+NU)/GAMMA(D(S)(+)-]PHI-PI+)
No full textComplete Author List:
ACOSTA D, ATHANAS M, MASEK G, PAAR H, BEAN A, GRONBERG J, KUTSCHKE R, MENARY S, MORRISON RJ, NAKANISHI S, NELSON HN, NELSON TK, RICHMAN JD, RYD A, TAJIMA H, SCHMIDT D, SPERKA D, WITHERELL MS, PROCARIO M, YANG S, BALEST R, CHO K, DAOUDI M, FORD WT, JOHNSON DR, LINGEL K, LOHNER M, RANKIN P, SMITH JG, ALEXANDER JP, BEBEK C, BERKELMAN K, BESSON D, BROWDER TE, CASSEL DG, CHO HA, COFFMAN DM, DRELL PS, EHRLICH R, GALIK RS, GARCIASCIVERES M, GEISER B, GITTELMAN B, GRAY SW, HARTILL DL, HELTSLEY BK, JONES CD, JONES SL, KANDASWAMY J, KATAYAMA N, KIM PC, KREINICK DL, LUDWIG GS, MASUI J, MEVISSEN J, MISTRY NB, NG CR, NORDBERG E, OGG M, PATTERSON JR, PETERSON D, RILEY D, SALMAN S, SAPPER M, WORDEN H, WURTHWEIN F, AVERY P, FREYBERGER A, RODRIGUEZ J, STEPHENS R, YELTON J, CINABRO D, HENDERSON S, KINOSHITA K, LIU T, SAULNIER M, SHEN F, WILSON R, YAMAMOTO H, ONG B, SELEN M, SADOFF AJ, AMMAR R, BALL S, BARINGER P, COPPAGE D, COPTY N, DAVIS R, HANCOCK N, KELLY M, KWAK N, LAM H, KUBOTA Y, LATTERY M, NELSON JK, PATTON S, PERTICONE D, POLING R, SAVINOV V, SCHRENK S, WANG R, ALAM MS, KIM IJ, NEMATI B, ONEILL JJ, SEVERINI H, SUN CR, ZOELLER MM, CRAWFORD G, DAUBENMIER CM, FULTON R, FUJINO D, GAN KK, HONSCHEID K, KAGAN H, KASS R, LEE J, MALCHOW R, MORROW F, SKOVPEN Y, SUNG M, WHITE C, WHITMORE J, WILSON P, BUTLER F, FU X, KALBFLEISCH G, LAMBRECHT M, ROSS WR, SKUBIC P, SNOW J, WANG PL, WOOD M, BORTOLETTO D, BROWN DN, FAST J, MCILWAIN RL, MIAO T, MILLER DH, MODESITT M, SCHAFFNER SF, SHIBATA EI, SHIPSEY IPJ, WANG PN, BATTLE M, ERNST J, KROHA H, ROBERTS S, SPARKS K, THORNDIKE EH, WANG CH, DOMINICK J, SANGHERA S, SHELKOV V, SKWARNICKI T, STROYNOWSKI R, VOLOBOUEV I, ZADOROZHNY P, ARTUSO M, HE D, GOLDBERG M, HORWITZ N, KENNETT R, MONETI GC, MUHEIM F, MUKHIN Y, PLAYFER S, ROZEN Y, STONE S, THULASIDAS M, VASSEUR G, ZHU G, BARTELT J, CSORNA SE, EGYED Z, JAIN V, SHELDON P, AKERIB DS, BARISH B, CHADHA M, CHAN S, COWEN DF, EIGEN G, MILLER JS, OGRADY C, URHEIM J, WEINSTEIN A
Tellurium(II) dialkanethiolates: n(p)(S)-sigma*(Te-S ') orbital interactions determine the Te-125 NMR chemical shift, and the molecular and crystal structure
No full textFleischer H, Mitzel NW, Schollmeyer D. Tellurium(II) dialkanethiolates: n(p)(S)-sigma*(Te-S ') orbital interactions determine the Te-125 NMR chemical shift, and the molecular and crystal structure. EUROPEAN JOURNAL OF INORGANIC CHEMISTRY. 2003;(5):815-821.Tellurium(II) dimethanethiolate, Te(SMe)(2), and tellurium(II) diethanethiolate, Te(SEt)(2), were synthesized by reaction of TeO2 and Te(OiPr)(4) with HSMe and HSEt, respectively. In the solid state, Te(SMe)(2) exhibits a cis-conformation of the methyl groups with respect to the TeS2 plane - an unprecedented situation for nonfunctionalized organotrichalcogenides - whereas Te(SEt)(2) shows a trans-conformation. Ab initio calculations performed for Te(SMe)(2) and Te(SEt)(2) show that the cis- and trans-conformers represent minima on the potential energy surface and are stabilized by intramolecular pi-type n(S)-sigma* (Te-S') orbital interactions. In the solid state, the molecules of each compound are associated through two centro-symmetric Te2S2 units with two of their neighbors, resulting in tetracoordinate Te atoms with distorted trapezoidal configurations. While the intermolecular Te...S distance increases in the sequence R = Me < Et < iPr < tBu, the length of the covalent Te-S bond decreases in the same order, a result attributed to intermolecular sigma-type n(p)(S)-sigma*(Te-S') orbital interactions. The Te-125 NMR chemical shift of Te(SR)(2) largely depends on R (R = Me, Et, iPr, tBu) and shows a nearly linear correlation with the first ionization energy of the corresponding thiol HSR. Ab initio calculations of the Te-125 NMR shifts for the model compound Te(SH)(2) (C-2 symmetry) reveal that it also depends strongly on the HSTeS torsion angle. These results can be explained by a model in which pi-type n(p)(S)- sigma*(Te-S') and n(p)(Te)-sigma*(S-H) orbital interactions determine the paramagnetic shielding of the tellurium nucleus. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 2003)
Measurement of CP violation in B0 → D+D− and B0s → D+s D−s decays
No full textA time-dependent, favour-tagged measurement of CP violation is performed
with B0 → D+D− and B0
s → D+
s D−
s decays, using data collected by the LHCb detector in
proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated
luminosity of 6 fb−1
. In B0 → D+D− decays the CP-violation parameters are measured to be
SD+D− = −0.552 ± 0.100 (stat) ± 0.010 (syst),
CD+D− = 0.128 ± 0.103 (stat) ± 0.010 (syst).
In B0
s → D+
s D−
s decays the CP-violating parameter formulation in terms of ϕs and |λ|
results in
ϕs = −0.086 ± 0.106 (stat) ± 0.028 (syst) rad,
|λD
+
s D
−
s
| = 1.145 ± 0.126 (stat) ± 0.031 (syst).
These results represent the most precise single measurement of the CP-violation parameters in
their respective channels. For the first time in a single measurement, CP symmetry is observed
to be violated in B0 → D+D− decays with a significance exceeding six standard deviations
Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
Angular analysis of B0 → D∗−D∗+s with D∗+s → D+sγ decays
No full textThe first full angular analysis of the B0 → 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 → D+
s γ and D∗− → D
0
π
− vector meson decays are used
with the subsequent D+
s → K+K−π
+ and 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(B0 → D∗−D∗+
s
) × B(D∗+
s → D+
s γ)]/B(B0 → D∗−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 decay is made with a significance of seven standard deviations. The branching fraction ratio B(Bs → D∗−D+
s
)/B(B0 → D∗−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
Measurement of CP asymmetries in D s + → η π + and D s + → η ′ π + decays
No full textAbstract Searches for CP violation in the decays D s + → η π + and D s + → η ′ π + are performed using pp collision data corresponding to 6 fb −1 of integrated luminosity collected by the LHCb experiment. The calibration channels D s + → ϕ π + are used to remove production and detection asymmetries. The resulting CP-violating asymmetries are A CP = D + → η π + = 0.34 ± 0.66 ± 0.16 ± 0.05 % , A CP = D s + → η π + = 0.32 ± 0.51 ± 0.12 % , A CP = D + → η ′ π + = 0.49 ± 0.18 ± 0.06 ± 0.05 % , A CP = D s + → η ′ π + = 0.01 ± 0.12 ± 0.08 % , where the first uncertainty is statistical, the second is systematic and the third, relevant for the D + channels, is due to the uncertainty on A CP = D + → ϕ π + . These measurements, currently the most precise for three of the four channels considered, are consistent with the absence of CP violation. A combination of these results with previous LHCb measurements is presented
Measurements of the absolute branching fractions for D-s(+) -> eta e(+)nu(e) and D-s(+) -> eta ' e(+)nu(e)
No full textBy analyzing 482 pb(-1) of e(+)e(-) collision data collected at root s = 4.009 GeV with the BESIII detector at the BEPCII collider, we measure the absolute branching fractions for the semileptonic decays D-s(+) -> eta e(+)nu(e) and D-s(+) -> eta ' e(+)nu(e) to be B(D-s(+) -> eta e(+)nu(e)) = (2.30 +/- 0.31 +/- 0.08)% and B(D-s(+) -> eta ' e(+)nu(e)) = (0.93 +/- 0.30 +/- 0.05)%, respectively, and their ratio B(D-s(+) -> eta ' e(+)nu(e)) / B(D-s(+) -> eta ' e(+)nu(e)) = 0.40 +/- 0.14 +/- 0.02, where the first uncertainties are statistical and the second ones are systematic. The results are in good agreement with previous measurements within uncertainties; they can be used to determine the eta-eta' mixing angle and improve upon the D-s(+) semileptonic branching ratio precision
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Experimental investigations and ab initio studies of selenium(II) dialkanethiolates, Se(SR)(2)
No full textFleischer H, Glang S, Schollmeyer D, Mitzel NW, Buhl M. Experimental investigations and ab initio studies of selenium(II) dialkanethiolates, Se(SR)(2). DALTON TRANSACTIONS. 2004;(21):3765-3771.Selenium(II) dimethanethiolate, Se(SMe)(2), was synthesized by reaction of SeO2 with HSMe. Basic spectroscopic data for Se(SMe)(2) and selenium(II) bis(2-methyl-2-propanethiolate), Se((SBu)-Bu-t)(2), were recorded and interpreted with the support of ab initio calculations. Both compounds are thermodynamically unstable relatively to selenium and the corresponding disulfide. The UV/vis spectra of both compounds are qualitatively similar, the two bands being attributed to n(Se)-sigma*(Se-S) transitions. The bands at 369 and 397 cm(-1) in the IR spectra of Se(SMe)(2) and Se((SBu)-Bu-t)(2), respectively, are assigned to nu(as)(SeS2). The Se-77 NMR shifts of Se(SMe)(2) (784 ppm) and Se((SBu)-Bu-t)(2) (556 ppm) differ substantially from each other and show positive temperature gradients. Calculations at the GIAO-HF/962+(d) level reproduced the difference of the Se-77 NMR chemical shifts between Se(SMe)(2) and Se((SBu)-Bu-t)(2). At the same level, the effect of conformational changes on Se-77 shifts were studied for Se(SMe)(2). In the solid state Se(SMe)(2) forms long intermolecular Se...S contacts while Se((SBu)-Bu-t)(2) does not. Both compounds exhibit anti-conformations of the methyl and tert-butyl groups with respect to the SeS2 plane. MP2/LANL2DZ(d) geometry optimizations, single point energy and frequency calculations performed for Se(SMe)(2) show, that syn- (C-s) and anti-conformers (C-2) represent minima on the potential energy surface, the latter being by 8 kJ mol(-1) lower in energy than the former. Both conformers are stabilized by intramolecular pi-type n(S-1)-sigma*(Se-S-2) orbital interactions. The energy of the transition state for the mutual conversion of the two conformers was calculated to be 31 kJ mol(-1) above that of the syn conformer, allowing a rapid interconversion of the two conformers at room temperature. Intermolecular interactions between Se(SMe)(2) molecules were also studied by means of calculations at the MP2/LANL2DZ(d) level. For Se((SBu)-Bu-t)(2) MP2/LANL2DZ(d) geometry optimizations and single point energy calculations revealed a C-2-symmetric anti- and a C-1 symmetric syn-conformer, the latter being 21 kJ mol(-1) higher in energy than the former. Se(SMe)(2) and Se((SBu)-Bu-t)(2) exchange thiolate groups with other selenium(II) dithiolates, tellurium(II) dithiolates and with thiols, if catalytic amounts of p-CH3C6H4SO3H are added
Search for the decay D-s(+) -> gamma e (+) nu(e)
No full textKolcu, Onur Buğra (Arel Author)A search for the rare radiative leptonic decay D-s(+) -> gamma e(+)nu(e) is performed for the first time using electron-positron collision data corresponding to an integrated luminosity of 3.19 fb(-1), collected with the BESIII detector at a center-of-mass energy of 4.178 GeV. No evidence for the D-s(+) -> gamma e(+)nu(e) decay is seen, and an upper limit of beta(D-s(+) -> gamma e(+)nu(e)) 0.01 GeV
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