Extending the Higgs sector: an extra singlet Godunov, S I.; Rozanov, A. N.; Vysotsky, M. I. ...
The European physical journal. C, Particles and fields,
2016/1, Letnik:
76, Številka:
1
Journal Article
Recenzirano
Odprti dostop
An extension of the Standard Model with an additional Higgs singlet is analyzed. Bounds on singlet admixture for the 125 GeV
h
boson from electroweak radiative corrections and data on
h
production ...and decays are obtained. The possibility of double
h
production enhancement at 14 TeV LHC due to a heavy Higgs contribution is considered.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
Ultraperipheral collisions of high energy protons are a source of approximately real photons colliding with each other. Photon fusion can result in production of yet unknown charged ...particles in very clean events. The cleanliness of such an event is due to the requirement that the protons survive during the collision. Finite sizes of the protons reduce the probability of such outcome compared to point-like particles. We calculate the survival factors and cross sections for the production of heavy charged particles at the Large Hadron Collider.
A
bstract
We propose a model-independent approach for the search of charged long-lived particles produced in ultraperipheral collisions at the LHC. The main idea is to improve event reconstruction at ...ATLAS and CMS with the help of their forward detectors. Detection of both scattered protons in forward detectors allows complete recovery of event kinematics. Though this requirement reduces the number of events, it greatly suppresses the background, including the large background from the pile-up.
Analytical formulas for the cross section of the reaction
p
p
→
p
+
ℓ
+
ℓ
-
+
X
are presented. Fiducial cross sections are compared with those measured recently by the ATLAS collaboration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Within the SPARC Data Initiative, the first comprehensive assessment of the quality of 13 water vapor products from 11 limb‐viewing satellite instruments (LIMS, SAGE II, UARS‐MLS, HALOE, POAM III, ...SMR, SAGE III, MIPAS, SCIAMACHY, ACE‐FTS, and Aura‐MLS) obtained within the time period 1978–2010 has been performed. Each instrument's water vapor profile measurements were compiled into monthly zonal mean time series on a common latitude‐pressure grid. These time series serve as basis for the “climatological” validation approach used within the project. The evaluations include comparisons of monthly or annual zonal mean cross sections and seasonal cycles in the tropical and extratropical upper troposphere and lower stratosphere averaged over one or more years, comparisons of interannual variability, and a study of the time evolution of physical features in water vapor such as the tropical tape recorder and polar vortex dehydration. Our knowledge of the atmospheric mean state in water vapor is best in the lower and middle stratosphere of the tropics and midlatitudes, with a relative uncertainty of ±2–6% (as quantified by the standard deviation of the instruments' multiannual means). The uncertainty increases toward the polar regions (±10–15%), the mesosphere (±15%), and the upper troposphere/lower stratosphere below 100 hPa (±30–50%), where sampling issues add uncertainty due to large gradients and high natural variability in water vapor. The minimum found in multiannual (1998–2008) mean water vapor in the tropical lower stratosphere is 3.5 ppmv (±14%), with slightly larger uncertainties for monthly mean values. The frequently used HALOE water vapor data set shows consistently lower values than most other data sets throughout the atmosphere, with increasing deviations from the multi‐instrument mean below 100 hPa in both the tropics and extratropics. The knowledge gained from these comparisons and regarding the quality of the individual data sets in different regions of the atmosphere will help to improve model‐measurement comparisons (e.g., for diagnostics such as the tropical tape recorder or seasonal cycles), data merging activities, and studies of climate variability.
Key Points
Validation of H2O climatologies from limb‐viewing satellite instruments
Key information on uncertainty for data merging or climate variability studies
Best quality of H2O in middle stratosphere, worst in UTLS
A comprehensive quality assessment of the ozone products from 18 limb‐viewing satellite instruments is provided by means of a detailed intercomparison. The ozone climatologies in form of monthly ...zonal mean time series covering the upper troposphere to lower mesosphere are obtained from LIMS, SAGE I/II/III, UARS‐MLS, HALOE, POAM II/III, SMR, OSIRIS, MIPAS, GOMOS, SCIAMACHY, ACE‐FTS, ACE‐MAESTRO, Aura‐MLS, HIRDLS, and SMILES within 1978–2010. The intercomparisons focus on mean biases of annual zonal mean fields, interannual variability, and seasonal cycles. Additionally, the physical consistency of the data is tested through diagnostics of the quasi‐biennial oscillation and Antarctic ozone hole. The comprehensive evaluations reveal that the uncertainty in our knowledge of the atmospheric ozone mean state is smallest in the tropical and midlatitude middle stratosphere with a 1σ multi‐instrument spread of less than ±5%. While the overall agreement among the climatological data sets is very good for large parts of the stratosphere, individual discrepancies have been identified, including unrealistic month‐to‐month fluctuations, large biases in particular atmospheric regions, or inconsistencies in the seasonal cycle. Notable differences between the data sets exist in the tropical lower stratosphere (with a spread of ±30%) and at high latitudes (±15%). In particular, large relative differences are identified in the Antarctic during the time of the ozone hole, with a spread between the monthly zonal mean fields of ±50%. The evaluations provide guidance on what data sets are the most reliable for applications such as studies of ozone variability, model‐measurement comparisons, detection of long‐term trends, and data‐merging activities.
Key Points
Quality assessment of ozone products from 18 limb‐viewing satellite instruments
Detailed intercomparison of monthly zonal mean ozone climatologies
Derived uncertainty in our knowledge of the atmospheric ozone mean state
Dilepton production in proton–proton collision through γγ-fusion with one proton scattered elastically while the second produces a hadron jet is considered. Semi-analytical formulas describing the ...cross section for a muon pair production are presented.
In the relatively recent CMS data, there is a hint on the existence of a resonance with the mass 28 GeV decaying to a μ+μ− pair and produced in association with a b quark jet and a second jet. Such a ...resonance should also couple to photons through the fermion loop, therefore, it can be searched for in ultraperipheral collisions (UPC) of protons. We set an upper bound on the Xγγ coupling constant from the data on μ+μ− pair production in UPC at the LHC. Our approach can be used for similar resonances should they appear in the future.
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