Search results for "LHC"
showing 10 items of 342 documents
New physics in $B$ meson mixing: future sensitivity and limitations
2020
The mixing of neutral mesons is sensitive to some of the highest scales probed in laboratory experiments. In light of the planned LHCb Upgrade II, a possible upgrade of Belle II, and the broad interest in flavor physics in the tera-Z phase of the proposed FCC-ee program, we study constraints on new physics contributions to Bd and Bs mixings which can be obtained in these benchmark scenarios. We explore the limitations of this program, and identify the measurement of |Vcb| as one of the key ingredients in which progress beyond current expectations is necessary to maximize future sensitivity. We speculate on possible solutions to this bottleneck. Given the current tension with the standard mo…
Multi-channel search for squarks and gluinos in root s=7 TeV pp collisions with the ATLAS detector at the LHC
2013
A search for supersymmetric particles in final states with zero, one, and two leptons, with and without jets identified as originating from b-quarks, in 4.7 fb[superscript −1] of √s = 7 TeV pp collisions produced by the Large Hadron Collider and recorded by the ATLAS detector is presented. The search uses a set of variables carrying information on the event kinematics transverse and parallel to the beam line that are sensitive to several topologies expected in supersymmetry. Mutually exclusive final states are defined, allowing a combination of all channels to increase the search sensitivity. No deviation from the Standard Model expectation is observed. Upper limits at 95 % confidence level…
Alignment of the ATLAS Inner Detector and Single Top Studies
2016
Alineamiento del detector interno de ATLAS y estudios del single top Esta tesis esta compuesta por dos partes bien diferenciadas. La primera trata de los estudios de alineamiento del detector interno del experimento ATLAS en el CERN. La segunda se centra en los estudios sobre el quark top cuando es producido como partícula aislada. ATLAS es uno de los grandes experimentos del LHC (Gran colisionador de hadrones) situado en el CERN. ATLAS es un detector de propósito general. Se diseñó para aprovechar la alta energía disponible en el LHC y observar fenómenos de física a muy altas energías. ATLAS está formado por varios sub-sistemas, como el detector interno de trazas, los calorímetros electrom…
Study of heavy meson production in p-Pb collisions at $\sqrt{S}$=5.02 TeV in the general-mass variable-flavour-number scheme
2017
Nuclear physics / B 925, 415 - 430 (2017). doi:10.1016/j.nuclphysb.2017.10.016
Search for CP violation using T-odd correlations in D-0 -> K+K-pi(+)pi(-) decays
2014
A search for $CP$ violation using $T$-odd correlations is performed using the four-body $D^0 \to K^+K^-\pi^+\pi^-$ decay, selected from semileptonic $B$ decays. The data sample corresponds to integrated luminosities of $1.0\,\text{fb}^{-1}$ and $2.0\,\text{fb}^{-1}$ recorded at the centre-of-mass energies of 7 TeV and 8 TeV, respectively. The $CP$-violating asymmetry $a_{CP}^{T\text{-odd}}$ is measured to be $(0.18\pm 0.29\text{(stat)}\pm 0.04\text{(syst)})\%$. Searches for $CP$ violation in different regions of phase space of the four-body decay, and as a function of the $D^0$ decay time, are also presented. No significant deviation from the $CP$ conservation hypothesis is found.
The TileCal Optical Multiplexer Board 9U
2011
Abstract TileCal is the hadronic calorimeter of the ATLAS experiment at LHC/CERN. The system contains roughly 10,000 channels of read-out electronics, whose signals are gathered and digitized in the front-end electronics and then transmitted to the counting room through two redundant optical links. Then, the data is received in the back-end system by the Optical Multiplexer Board (OMB) 9U which performs a CRC check to the redundant data to avoid Single Event Upsets errors. A real-time decision is taken on the event-to-event basis to transmit single data to the Read-Out Drivers (RODs) for processing. Due to the low dose level expected during the first years of operations in ATLAS it was deci…
Filling the “green gap” of the major light-harvesting chlorophyll a/b complex by covalent attachment of Rhodamine Red
2009
AbstractThe major light-harvesting chlorophyll a/b complex (LHCII) greatly enhances the efficiency of photosynthesis in green plants. Recombinant LHCII can be assembled in vitro from its denatured, bacterially expressed apoprotein and plant pigments. This makes it an interesting candidate for biomimetic light-harvesting in photovoltaic applications. Due to its almost 20 pigments bound per apoprotein, LHCII absorbs efficiently in the blue and red spectral domains of visible light but less efficiently in the green domain, the so-called “green gap” in its absorption spectrum. Here we present a hybrid complex of recombinant LHCII with organic dyes that add to LHCII absorption in the green spect…
Performance of jet substructure techniques for large-$R$ jets in proton-proton collisions at $\sqrt{s}$ = 7 TeV using the ATLAS detector
2013
This paper presents the application of a variety of techniques to study jet substructure. The performance of various modified jet algorithms, or jet grooming techniques, for several jet types and event topologies is investigated for jets with transverse momentum larger than 300 GeV. Properties of jets subjected to the mass-drop filtering, trimming, and pruning algorithms are found to have a reduced sensitivity to multiple proton-proton interactions, are more stable at high luminosity and improve the physics potential of searches for heavy boosted objects. Studies of the expected discrimination power of jet mass and jet substructure observables in searches for new physics are also presented.…
Thermal stability of trimeric light-harvesting chlorophyll a/b complex (LHCIIb) in liposomes of thylakoid lipids.
2006
The major light-harvesting chlorophyll a/b complex (LHCIIb) of photosystem (PS) II functions by harvesting light energy and by limiting and balancing the energy flow directed towards the PSI and PSII reaction centers. The complex is predominantly trimeric; however, the monomeric form may play a role in one or several of the regulatory functions of LHCIIb. In this work the dissociation temperature was measured of trimeric LHCIIb isolated from Pisum thylakoids and inserted into liposomes made of various combinations of thylakoid lipids at various protein densities. Dissociation was measured by monitoring a trimer-specific circular dichroism signal in the visible range. The LHCIIb density in t…
Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 7 TeV proton-proton collision data wi…
2012
A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, and at least one hadronically decaying τ lepton, with zero or one additional light lepton (e/μ), has been performed using 4.7 fb[superscript −1] of proton-proton collision data at √s = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95 % confidence level visible cross-sectionupper limit for new phenomena is set. In the framework of gauge-mediated SUSY-breaking models, lower limits on the mass scale Λ are set at 54 TeV in the regions where the [bar over τ]1 is the next-to-lightest SUSY particle (tanβ > 20). …