In this study, a search for evidence of particle dark matter (DM) and unparticle production at the LHC has been performed using events containing two charged leptons, consistent with the decay of a Z ...boson, and large missing transverse momentum. This study is based on data collected with the CMS detector corresponding to an integrated luminosity of 19.7 fb–1 of pp collisions at the LHC at a center-of-mass energy of 8 TeV. No significant excess of events is observed above the number expected from the standard model contributions. The results are interpreted in terms of 90% confidence level limits on the DM-nucleon scattering cross section, as a function of the DM particle mass, for both spin-dependent and spin-independent scenarios. Limits are set on the effective cutoff scale Lambda, and on the annihilation rate for DM particles, assuming that their branching fraction to quarks is 100%. Additionally, the most stringent 95% confidence level limits to date on the unparticle model parameters are obtained.
A search for massive resonances decaying to a Z boson and a photon is performed in events with a hadronically decaying Z boson candidate, separately in light-quark and b quark decay modes, identified ...using jet substructure and advanced b tagging techniques. Results are based on samples of proton–proton collisions collected with the CMS detector at the LHC at center-of-mass energies of 8 and 13TeV, corresponding to integrated luminosities of 19.7 and 2.7 fb−1, respectively. The results of the search are combined with those of a similar search in the leptonic decay modes of the Z boson, based on the same data sets. Spin-0 resonances with various widths and with masses in a range between 0.2 and 3.0TeV are considered. No significant excess is observed either in the individual analyses or the combination. The results are presented in terms of upper limits on the production cross section of such resonances and constitute the most stringent limits to date for a wide range of masses.
Larval fish originating south of Cape Hatteras, North Carolina, are frequently found on the continental shelf north of Cape Hatteras, even as far north as the Scotian shelf. The Gulf Stream and ...associated warm-core rings are hypothesized as the physical mechanisms responsible for the northward transport of larvae. Specifically, larvae spawned along the southeast U.S. continental shelf are entrained into the Gulf Stream, transported to the northeast, regularly incorporated in warm-core ring streamers, transported across the slope region, and released along the shelf edge north of Cape Hatteras. This proposed transport route was evaluated using hydrographic data and drifter tracks that were collected as part of other studies. Continental shelf water that originated south of Cape Hatteras was found along the edge of the Gulf Stream north of Cape Hatteras, and drifter tracks demonstrated each segment of the proposed transport route. A probability model was then developed to estimate transport times for larvae carried over the proposed transport route using a combination of sea surface temperature images, statistics of drifter transport speeds, and a larval mortality function. Modeled transport time distributions closely matched observed age distributions of larvae, further supporting the hypothesized transport route.
A
bstract
Results are reported from a search for supersymmetric particles in proton-proton collisions in the final state with a single, high transverse momentum lepton; multiple jets, including at ...least one b-tagged jet; and large missing transverse momentum. The data sample corresponds to an integrated luminosity of 2.3 fb
−1
at
s
=
13
TeV, recorded by the CMS experiment at the LHC. The search focuses on processes leading to high jet multiplicities, such as gluino pair production with
g
˜
→
t
t
¯
χ
˜
1
0
. The quantity
M
J
, defined as the sum of the masses of the large-radius jets in the event, is used in conjunction with other kinematic variables to provide discrimination between signal and background and as a key part of the background estimation method. The observed event yields in the signal regions in data are consistent with those expected for standard model backgrounds, estimated from control regions in data. Exclusion limits are obtained for a simplified model corresponding to gluino pair production with three-body decays into top quarks and neutralinos. Gluinos with a mass below 1600 GeV are excluded at a 95% confidence level for scenarios with low
χ
˜
1
0
mass, and neutralinos with a mass below 800 GeV are excluded for a gluino mass of about 1300 GeV. For models with two-body gluino decays producing on-shell top squarks, the excluded region is only weakly sensitive to the top squark mass.
A
bstract
The cross section for Higgs boson production in pp collisions is studied using the H → W
+
W
−
decay mode, followed by leptonic decays of the W bosons to an oppositely charged electron-muon ...pair in the final state. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.4 fb
−1
. The Higgs boson transverse momentum (
p
T
) is reconstructed using the lepton pair
p
T
and missing
p
T
. The differential cross section times branching fraction is measured as a function of the Higgs boson
p
T
in a fiducial phase space defined to match the experimental acceptance in terms of the lepton kinematics and event topology. The production cross section times branching fraction in the fiducial phase space is measured to be 39 ± 8 (stat) ± 9 (syst) fb. The measurements are found to agree, within experimental uncertainties, with theoretical calculations based on the standard model.
In April 2009, an outbreak of novel swine-origin influenza A (2009 H1N1 influenza) occurred at a high school in Queens, New York. We describe the outbreak and characterize the clinical and ...epidemiologic aspects of this novel virus.
The New York City Department of Health and Mental Hygiene characterized the outbreak through laboratory confirmation of the presence of the 2009 H1N1 virus in nasopharyngeal and oropharyngeal specimens and through information obtained from an online survey. Detailed information on exposure and the onset of symptoms was used to estimate the incubation period, generation time, and within-school reproductive number associated with 2009 H1N1 influenza, with the use of established techniques.
From April 24 through May 8, infection with the 2009 H1N1 virus was confirmed in 124 high-school students and employees. In responses to the online questionnaire, more than 800 students and employees (35% of student respondents and 10% of employee respondents) reported having an influenza-like illness during this period. No persons with confirmed 2009 H1N1 influenza or with influenza-like illness had severe symptoms. A linkage with travel to Mexico was identified. The estimated median incubation period for confirmed 2009 H1N1 influenza was 1.4 days (95% confidence interval CI, 1.0 to 1.8), with symptoms developing in 95% of cases by 2.2 days (95% CI, 1.7 to 2.6). The estimated median generation time was 2.7 days (95% CI, 2.0 to 3.5). We estimate that the within-school reproductive number was 3.3.
The findings from this investigation suggest that 2009 H1N1 influenza in the high school was widespread but did not cause severe illness. The reasons for the rapid and extensive spread of influenza-like illnesses are unknown. The natural history and transmission of the 2009 H1N1 influenza virus appear to be similar to those of previously observed circulating pandemic and interpandemic influenza viruses.
A measurement is presented of differential cross sections for Higgs boson (H) production in pp collisions at
s
=
8
TeV
. The analysis exploits the
H
→
γ
γ
decay in data corresponding to an integrated ...luminosity of 19.7
fb
-1
collected by the CMS experiment at the LHC. The cross section is measured as a function of the kinematic properties of the diphoton system and of the associated jets. Results corrected for detector effects are compared with predictions at next-to-leading order and next-to-next-to-leading order in perturbative quantum chromodynamics, as well as with predictions beyond the standard model. For isolated photons with pseudorapidities
|
η
|
<
2.5
, and with the photon of largest and next-to-largest transverse momentum (
p
T
γ
) divided by the diphoton mass
m
γ
γ
satisfying the respective conditions of
p
T
γ
/
m
γ
γ
>
1
/
3
and
>
1
/
4
, the total fiducial cross section is
32
±
10
\,fb
.
A
bstract
A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in
t
-channel single top quark production is presented. It is based on a sample of pp ...collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb
−1
. A high-purity sample of
t
-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. A differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 ± 0.03(stat) ± 0.10(syst), which is compatible with a
p
-value of 4.6% with the standard model prediction of 0.44.
We sought to evaluate the effectiveness and safety of utilizing radiotherapy (RT) with standard fractionation, with or without intraoperative RT (IORT), to treat locally recurrent rectal cancer ...(LRRC).
Retrospective review of 25 patients with LRRC treated with standard fractionation RT from 2005 to 2011. 15 patients (60%) had prior pelvic RT and 10 (40%) had synchronous metastases. The median equivalent dose in 2-Gy fractions was 30 and 49.6 Gy in patients with and without prior RT, respectively. 23 patients (92%) received concurrent chemotherapy and 16 (64%) underwent surgical resection. Eight patients (33.3%, four with and four without prior RT) received IORT. A competing risks model was developed to estimate the cumulative incidence of local failure with death treated as a competing event.
Median follow-up was 36.9 months after the date of local recurrence. 3-year rates of overall survival (OS), local control (LC) and death with LC were 51.6%, 73.3% and 69.2%, respectively. On multivariable analysis, surgical resection was significantly predictive of improved OS (p < 0.05). If surgical resection were removed from the multivariable model, given the collinearity between IORT delivery and surgical resection, then IORT also became a significant predictor of OS (p < 0.05). Systemic disease at the time of local recurrence was not associated with either LC or OS. No patient had grade ≥3 acute or late toxicity.
RT with standard fractionation is safe and effective in the treatment of patients with LRRC, even in patients with significant risk of systemic disease and/or history of prior RT. Advances in knowledge: The utility of RT with standard fractionation, generally with chemotherapy, in the treatment of LRRC is demonstrated. In this high-risk cohort of patients with a 40% incidence of synchronous metastatic disease, surgical resection of the recurrence was the major predictor of OS, though a benefit to IORT was also suggested. No patients had grade ≥3 acute or late toxicity, though 40% had undergone prior RT, underscoring the tolerability of standard fractionation RT in this setting.
The production cross section of a W boson in association with two b jets is measured using a sample of proton–proton collisions at
s
=
8
TeV
collected by the CMS experiment at the CERN LHC. The data ...sample corresponds to an integrated luminosity of 19.8
fb
-1
. The W bosons are reconstructed via their leptonic decays,
W
→
ℓ
ν
, where
ℓ
=
μ
or
e
. The fiducial region studied contains exactly one lepton with transverse momentum
p
T
ℓ
>
30
GeV
and pseudorapidity
|
η
ℓ
|
<
2.1
, with exactly two b jets with
p
T
>
25
GeV
and
|
η
|
<
2.4
and no other jets with
p
T
>
25
GeV
and
|
η
|
<
4.7
. The cross section is measured to be
σ
(
p
p
→
W
(
ℓ
ν
)
+
b
b
¯
)
=
0.64
±
0.03
(
stat
)
±
0.10
(
syst
)
±
0.06
(
theo
)
±
0.02
(
lumi
)
pb
, in agreement with standard model predictions.
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