95,507 research outputs found
Alfred A. Alvarez Interview
No full textLTC Alfred A. Alvarez was born in 1924 and grew up in Chelsea, Massachusetts. He enlisted in July 1942 and following stateside training joined the 1st Infantry Division in England. He took part in the Normandy invasion, hitting "Easy Red," Omaha Beach on D-Day. He subsequently saw action in the Champagne campaigns and at Hurtgen Forest, the Battle of the Bulge, and in Czechoslovakia. Alvarez re-enlisted in the Reserves in 1945 and during his thirty-two years of duty served combat tours in Korea and Vietnam and was deployed to Central and South America. He was inducted into the U. S. Army OCS Hall of Fame in April 2003. This interview covers his service in World War II
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
First observations of B̅[0 over s]→D[superscript +]D[superscript -], D[+ over s]D[superscript -] and D[superscript 0]D̅[superscript 0] decays
No full textFirst observations and measurements of the branching fractions of the B̅[0 over s]→D[superscript +]D[superscript -], B̅[0 over s]→D[+ over s]D[superscript -] and B̅[0 over s]→D[superscript 0]D̅[superscript 0] decays are presented using 1.0 fb[superscript -1] of data collected by the LHCb experiment. These branching fractions are normalized to those of B̅[superscript 0]→D[superscript +]D[superscript -], B[superscript 0]→D[superscript -]D[+ over s] and B[superscript -]→D[superscript 0]D[- over s], respectively. An excess of events consistent with the decay B̅[superscript 0]→D[superscript 0]D̅[superscript 0] is also seen, and its branching fraction is measured relative to that of B[superscript -]→D[superscript 0]D[- over s]. Improved measurements of the branching fractions B(B̅[0 over s]→D[+ over s]D[- over s]) and B(B[superscript -]→D[superscript 0]D[- over s]) are reported, each relative to B(B[superscript 0]→D[superscript -]D[+ over s]). The ratios of branching fractions are B(B̅[0 over s]→D[superscript +]D[superscript -])/B(B̅[superscript 0]→D[superscript +]D[superscript -])=1.08±0.20±0.10, B(B̅[0 over s]→D[+ over s]D[superscript -])/B(B[superscript 0]→D[superscript -]D[+ over s])=0.050±0.008±0.004, B(B̅[0 over s]→D[superscript 0]D̅[superscript 0])/B(B[superscript -]→D[superscript 0]D[- over s])=0.019±0.003±0.003, B(B̅[superscript 0]→D[superscript 0]D̅[superscript 0])/B(B[superscript -]→D[superscript 0]D[- over s])<0.0024 at 90% CL, B(B̅[0 over s]→D[+ over s]D[- over s])/B(B[superscript 0]→D[superscript -]D[+ over s])=0.56±0.03±0.04, B(B[superscript -]→D[superscript 0]D[- over s])/B(B[superscript 0]→D[superscript -]D[+ over s])=1.22±0.02±0.07, where the uncertainties are statistical and systematic, respectively.National Science Foundation (U.S.
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
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)
Measurements of the branching fractions of the decays B0s→D∓sK± and B0s→D−sπ+
No full textThe decay mode B0s→D∓sK± allows for one of the theoretically cleanest measurements of the CKM angle γ through the study of time-dependent CP violation. This paper reports a measurement of its branching fraction relative to the Cabibbo-favoured mode B0s→D−sπ+ based on a data sample corresponding to 0.37 fb−1 of proton-proton collisions at s√=7TeV collected in 2011 with the LHCb detector. In addition, the ratio of B meson production fractions f s /f d , determined from semileptonic decays, together with the known branching fraction of the control channel B 0 → D −π+, is used to perform an absolute measurement of the branching fractions: B(B0s→D−sπ+)=(2.95±0.05±0.17+0.18−0.22)×10−3,\hfillB(B0s→D∓sK±)=(1.90±0.12±0.13+0.12−0.14)×10−4,\hfill where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to f s /f d
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
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
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
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
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
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