147 research outputs found
First Observation of the Decays (B)over-bar(0) -> D+K-pi(+)pi(-) and B- -> (DK-)-K-0 pi(+)pi(-)
First observations of the Cabibbo-suppressed decays B¯0 → D+K-π+π- and B- → D0K-π+π- are reported using 35 pB-1 of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo-favored decays, from which we obtain B(B¯0→ D+K-π+π-)/B(B¯0→D+π-π+π-)=(5.9±1.1±0.5)×10-2 and B(B-→D0K-π+π-)/B(B-→ D0π-π+π-)=(9.4±1.3±0.9)×10-2, where the uncertainties are statistical and systematic, respectively. The B- → D0K-π+π- decay is particularly interesting, as it can be used in a similar way to B- → D0K- to measure the Cabibbo-Kobayashi-Maskawa phase γ. © 2012 CERN
Strong Constraints on the Rare Decays B-s(0) -> mu(+)mu(-) and B-0 -> mu(+)mu(-)
A search for Bs0→
Performance of the LHCb Vertex Detector Alignment Algorithm determined with Beam Test Data
LHCb is the dedicated heavy flavour experiment at the Large Hadron Collider
at CERN. The partially assembled silicon vertex locator (VELO) of the LHCb
experiment has been tested in a beam test. The data from this beam test have
been used to determine the performance of the VELO alignment algorithm. The
relative alignment of the two silicon sensors in a module and the relative
alignment of the modules has been extracted. This alignment is shown to be
accurate at a level of approximately 2 micron and 0.1 mrad for translations and
rotations, respectively in the plane of the sensors. A single hit precision at
normal track incidence of about 10 micron is obtained for the sensors. The
alignment of the system is shown to be stable at better than the 10 micron
level under air to vacuum pressure changes and mechanical movements of the
assembled system.Comment: accepted for publication in NIM
Measurement of the proton and deuteron structure functions, F2p and F2d, and of the ratio sigma(L)/sigma(T)
The muon-proton and muon-deuteron inclusive deep inelastic scattering cross
sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q2 <
75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results
are based on the full data set collected by the New Muon Collaboration,
including the data taken with a small angle trigger. The extracted values of
the structure functions F2p and F2d are in good agreement with those from other
experiments. The data cover a sufficient range of y to allow the determination
of the ratio of the longitudinally to transversely polarised virtual photon
absorption cross sections, R= sigma(L)/sigma(T), for 0.002 < x < 0.12 . The
values of R are compatible with a perturbative QCD prediction; they agree with
earlier measurements and extend to smaller x.Comment: In this replacement the erroneously quoted R values in tables 3-6 for
x>0.12, and R1990 values in tables 5-6 for all x, have been corrected, and
the cross sections in tables 3-4 have been adapted. Everything else,
including the structure functions F2, remained unchanged. 22 pages, LateX,
including figures, with two .sty files, and three separate f2tab.tex files
for the F2-tables. Accepted for publication in Nucl.Phys.B 199
Large enhancement of deuteron polarization with frequency modulated microwaves
We report a large enhancement of 1.7 in deuteron polarization up to values of
0.6 due to frequency modulation of the polarizing microwaves in a two liters
polarized target using the method of dynamic nuclear polarization. This target
was used during a deep inelastic polarized muon-deuteron scattering experiment
at CERN. Measurements of the electron paramagnetic resonance absorption spectra
show that frequency modulation gives rise to additional microwave absorption in
the spectral wings. Although these results are not understood theoretically,
they may provide a useful testing ground for the deeper understanding of
dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar
files in poltar.uu, which also brings cernart.sty and crna12.sty files neede
On the macroscopic formation length for GeV photons
Experimental results for the radiative energy loss of 206 and 234 GeV electrons in 5–10 μm thin Ta targets are presented. An increase in radiation emission probability at low photon energies compared to a 100 μm thick target is observed. This increase is due to the formation length of the GeV photons exceeding the thickness of the thin foils, the so-called Ternovskii–Shul'ga–Fomin (TSF) effect. The formation length of GeV photons from a multi-hundred GeV projectile is through the TSF effect shown directly to be a factor 1010 longer than their wavelength
Measurement of the proton and the deuteron structure functions F2p and F2d
The proton and deuteron structure functions F2p and F2d were measured in the
kinematic range 0.006<x<0.6 and 0.5<Q^2<75 GeV^2, by inclusive deep inelastic
muon scattering at 90, 120, 200 and 280 GeV. The measurements are in good
agreement with earlier high precision results. The present and earlier results
together have been parametrised to give descriptions of the proton and deuteron
structure functions F2 and their uncertainties over the range 0.006<x<0.9.Comment: 22 pages, using LATEX, 12pt, epsfig.sty, rotating.sty; 2 tables and 6
figures uuencoded compressed tar files in f2fig.uu (Corrected two values of
Table 3 into c3=-35.01 and c4=44.43 for "Upper F2p".
A Re-Evaluation of the nuclear Structure Function Ratios for D, He, Li, C and Ca
We present a re-evaluation of the structure function ratios F2(He)/F2(D),
F2(C)/F2(D) and F2(Ca)/F2(D) measured in deep inelastic muon-nucleus scattering
at an incident muon momentum of 200 GeV. We also present the ratios
F2(C)/F2(Li), F2(Ca)/F2(Li) and F2(Ca)/F2(C) measured at 90 GeV. The results
are based on data already published by NMC; the main difference in the analysis
is a correction for the masses of the deuterium targets and an improvement in
the radiative corrections. The kinematic range covered is 0.0035 < x < 0.65,
0.5 < Q^2 <90 GeV^2 for the He/D, C/D and Ca/D data and 0.0085 < x < 0.6, 0.84
< Q^2 < 17 GeV^2 for the Li/C/Ca ones.Comment: 6 pages, Latex, 3 figures as uuencoded compressed tar file included
at the end, in case of problems contact [email protected] (Antje
Bruell
Accurate Measurement of F2d/F2p and Rd-Rp
Results are presented for F2d/F2p and Rd-Rp from simultaneous measurements of
deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120,
200 and 280 GeV. The difference Rd-Rp, determined in the range 0.002<x<0.4 at
an average Q^2 of 5 GeV^2, is compatible with zero. The x and Q^2 dependence of
F2d/F2p was measured in the kinematic range 0.001<x<0.8 and 0.1<Q^2<145 GeV^2
with small statistical and systematic errors. For x>0.1 the ratio decreases
with Q^2.Comment: 29 pages, LateX, including figures, prepared with uufiles, arriving
with .sty files as used, figures .eps files and a table .tex file. Accepted
for publication in Nucl.Phys.B 199
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