474 research outputs found
Supersymmetric Monojets at the Large Hadron Collider
Supersymmetric monojets may be produced at the Large Hadron Collider by the
process qg -> squark neutralino_1 -> q neutralino_1 neutralino_1, leading to a
jet recoiling against missing transverse momentum. We discuss the feasibility
and utility of the supersymmetric monojet signal. In particular, we examine the
possible precision with which one can ascertain the neutralino_1-squark-quark
coupling via the rate for monojet events. Such a coupling contains information
on the composition of the neutralino_1 and helps bound dark matter direct
detection cross-sections and the dark matter relic density of the neutralino_1.
It also provides a check of the supersymmetric relation between gauge couplings
and gaugino-quark-squark couplings.Comment: 46 pages, 10 figures. The appendix has been rewritten to correct an
error that appears in all previous versions of the appendix. This error has
no effect on the results in the main body of the pape
Higher-order multipole amplitudes in charmonium radiative transitions
Using 24 million decays in CLEO-c, we have searched
for higher multipole admixtures in electric-dipole-dominated radiative
transitions in charmonia. We find good agreement between our data and
theoretical predictions for magnetic quadrupole (M2) amplitudes in the
transitions and ,
in striking contrast to some previous measurements. Let and
denote the normalized M2 amplitudes in the respective aforementioned decays,
where the superscript refers to the angular momentum of the . By
performing unbinned maximum likelihood fits to full five-parameter angular
distributions, we determine the ratios and , where
the theoretical predictions are independent of the charmed quark magnetic
moment and are and .Comment: 32 pages, 7 figures, acceptance updat
Geospatial transmission hotspots of recent HIV infection â Malawi, October 2019âMarch 2020
What is already known about this topic? A novel HIV infection surveillance initiative was implemented in Malawi to collect data on recent HIV infections among new diagnoses to characterize the epidemic and guide the public health response. What is added by this report? Higher proportions of recent infections were identified among females, persons aged <30 years, and clients at maternal and child health and youth clinics. Spatial analysis identified three hotspots of health facilities with significantly higher rates of recent infection than expected across five districts. What are the implications for public health practice? Geospatial analysis of recent HIV infection surveillance data can identify potential transmission hotspots. This information could be used to tailor program activities to strengthen HIV testing, prevention, and treatment services and ultimately interrupt transmission
Search for D0 to p e- and D0 to pbar e+
Using data recorded by CLEO-c detector at CESR, we search for simultaneous
baryon and lepton number violating decays of the D^0 meson, specifically, D^0
--> p-bar e^+, D^0-bar --> p-bar e^+, D^0 --> p e^- and D^0-bar --> p e^-. We
set the following branching fraction upper limits: D^0 --> p-bar e^+ (D^0-bar
--> p-bar e^+) p e^- (D^0-bar --> p e^-) < 1.2 *
10^{-5}, both at 90% confidence level.Comment: 10 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PRD. Comments: changed abstract, added reference for section 1,
vertical axis in Fig.5 changed (starts from 1.5 rather than 2.0), fixed typo
Dalitz Plot Analysis of Ds to K+K-pi+
We perform a Dalitz plot analysis of the decay Ds to K+K-pi+ with the CLEO-c
data set of 586/pb of e+e- collisions accumulated at sqrt(s) = 4.17 GeV. This
corresponds to about 0.57 million D_s+D_s(*)- pairs from which we select 14400
candidates with a background of roughly 15%. In contrast to previous
measurements we find good agreement with our data only by including an
additional f_0(1370)pi+ contribution. We measure the magnitude, phase, and fit
fraction of K*(892) K+, phi(1020)pi+, K0*(1430)K+, f_0(980)pi+, f_0(1710)pi+,
and f_0(1370)pi+ contributions and limit the possible contributions of other KK
and Kpi resonances that could appear in this decay.Comment: 21 Pages,available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
Charmonium decays to gamma pi0, gamma eta, and gamma eta'
Using data acquired with the CLEO-c detector at the CESR e+e- collider, we
measure branching fractions for J/psi, psi(2S), and psi(3770) decays to gamma
pi0, gamma eta, and gamma eta'. Defining R_n = B[ psi(nS)-->gamma eta ]/B[
psi(nS)-->gamma eta' ], we obtain R_1 = (21.1 +- 0.9)% and, unexpectedly, an
order of magnitude smaller limit, R_2 < 1.8% at 90% C.L. We also use
J/psi-->gamma eta' events to determine branching fractions of improved
precision for the five most copious eta' decay modes.Comment: 14 pages, available through http://www.lns.cornell.edu/public/CLNS/,
published in Physical Review
Precision Measurement of B(D+ -> mu+ nu) and the Pseudoscalar Decay Constant fD+
We measure the branching ratio of the purely leptonic decay of the D+ meson
with unprecedented precision as B(D+ -> mu+ nu) = (3.82 +/- 0.32 +/-
0.09)x10^(-4), using 818/pb of data taken on the psi(3770) resonance with the
CLEO-c detector at the CESR collider. We use this determination to derive a
value for the pseudoscalar decay constant fD+, combining with measurements of
the D+ lifetime and assuming |Vcd| = |Vus|. We find fD+ = (205.8 +/- 8.5 +/-
2.5) MeV. The decay rate asymmetry [B(D+ -> mu+ nu)-B(D- -> mu- nu)]/[B(D+ ->
mu+ nu)+B(D- -> mu- nu)] = 0.08 +/- 0.08, consistent with no CP violation. We
also set 90% confidence level upper limits on B(D+ -> tau+ nu) < 1.2x10^(-3)
and B(D+ -> e+ nu) < 8.8x10^(-6).Comment: 24 pages, 11 figures and 6 tables, v2 replaced some figure vertical
axis scales, v3 corrections from PRD revie
Precision Measurement of the Mass of the h_c(1P1) State of Charmonium
A precision measurement of the mass of the h_c(1P1) state of charmonium has
been made using a sample of 24.5 million psi(2S) events produced in e+e-
annihilation at CESR. The reaction used was psi(2S) -> pi0 h_c, pi0 -> gamma
gamma, h_c -> gamma eta_c, and the reaction products were detected in the
CLEO-c detector.
Data have been analyzed both for the inclusive reaction and for the exclusive
reactions in which eta_c decays are reconstructed in fifteen hadronic decay
channels. Consistent results are obtained in the two analyses. The averaged
results of the present measurements are M(h_c)=3525.28+-0.19 (stat)+-0.12(syst)
MeV, and B(psi(2S) -> pi0 h_c)xB(h_c -> gamma eta_c)= (4.19+-0.32+-0.45)x10^-4.
Using the 3PJ centroid mass, Delta M_hf(1P)= - M(h_c) =
+0.02+-0.19+-0.13 MeV.Comment: 9 pages, available through http://www.lns.cornell.edu/public/CLNS/,
submitted to PR
J/psi and psi(2S) Radiative Transitions to eta_c
Using 24.5 million psi(2S) decays collected with the CLEO-c detector at CESR
we present the most precise measurements of magnetic dipole transitions in the
charmonium system. We measure B(psi(2S)->gamma eta_c) =
(4.32+/-0.16+/-0.60)x10^-3, B(J/psi->gamma eta_c)/B(psi(2S)->gamma eta_c) =
4.59+/-0.23+/-0.64, and B(J/psi->gamma eta_c) = (1.98+/-0.09+/-0.30)%. We
observe a distortion in the eta_c line shape due to the photon-energy
dependence of the magnetic dipole transition rate. We find that measurements of
the eta_c mass are sensitive to the line shape, suggesting an explanation for
the discrepancy between measurements of the eta_c mass in radiative transitions
and other production mechanisms.Comment: 11 pages, 3 figure
Inclusive chi_bJ(nP) Decays to D0 X
Using Upsilon(2S) and Upsilon(3S) data collected with the CLEO III detector
we have searched for decays of chi_bJ to final states with open charm. We fully
reconstruct D0 mesons with p_D0 > 2.5 GeV/c in three decay modes (K-pi+,
K-pi+pi0, and K-pi-pi+pi+) in coincidence with radiative transition photons
that tag the production of one of the chi_bJ(nP) states. We obtain significant
signals for the two J=1 states. Recent NRQCD calculations of chi_{bJ}(nP) --> c
cbar X depend on one non-perturbative parameter per chi_bJ triplet. The
extrapolation from the observed D0 X rate over a limited momentum range to a
full c cbar X rate also depends on these same parameters. Using our data to fit
for these parameters, we extract results which agree well with NRQCD
predictions, confirming the expectation that charm production is largest for
the J=1 states. In particular, for J=1, our results are consistent with c cbar
g accounting for about one-quarter of all hadronic decays.Comment: Version 2 updates include corrections to important errors in Table V
and VII column headers which summarize results, and additional minor edits.
17 pages, available through http://www.lns.cornell.edu/public/CLNS
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