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At least 505 records · Page 28Linked to original sources
arXiv2013

Coherent Scattering Investigations at the Spallation Neutron Source: a Snowmass White Paper

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, Tennessee, provides an intense flux of neutrinos in the few tens-of-MeV range, with a sharply-pulsed timing structure that is beneficial for background rejection. In this white paper, we describe how the SNS source can be used for a measurement of coherent elastic neutrino-nucleus scattering (CENNS), and the physics reach of different phases of such an experimental program (CSI: Coherent Scattering Investigations at the SNS).

hep-ex↗
arXiv2013

Measurements of VV Boson Production And Self-Interactions in The Semileptonic Channel at CMS

We present a summary of the latest measurements of the VV crosssections, where V=W or Z and one of the bosons decays into a pair of jets while the other decays leptonically. The data sample(s) correspond to proton-proton collision events collected with the CMS detector at sqrt{s} = 7 TeV. Subsequent searches for Anomalous Triple Gauge couplings, which allow us to probe the non-Abelian structure in the Electroweak Sector, are described. We present the exclusion limits on the corresponding couplings.

hep-ex↗
arXiv2013

The LHCb Upgrade

The LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux involving beauty and charm quarks produced at the LHC. The operation and the results obtained from the data collected in 2010 and 2011 demonstrate that the detector is robust and functioning very well. However, the limit of 1 fb^-1 of data per nominal year cannot be overcome without improving the detector. We therefore plan for an upgraded spectrometer by 2018 with a 40 MHz readout and a much more flexible software-based triggering system that will increase the data rate as well as the efficiency specially in the hadronic channels. Here we present the LHCb detector upgrade plans, based on the Letter of Intent and Framework Technical Design Report.

physics.ins-det↗
arXiv2013

An improved measurement of direct CP violation parameters in B^pm -> J/psi K^pm and B^pm -> J/psi pi^pm decays

We present a measurement of the direct CP-violating charge asymmetry in B^pm mesons decaying to J/psi K^pm and J/psi pi^pm where J/psi decays to mu^+ mu^-, using 10.4 fb$^-1 of proton-antiproton collisions collected by the D0 detector during Run II at the Fermilab Tevatron Collider. A difference in the yield of B^- and B^+ mesons in these decays is found by fitting to the difference between their reconstructed invariant mass distributions resulting in asymmetries of ajpk =[ 0.59 \pm 0.36 ]%, which is the most precise measurement to date, and ajppi= [ -4.2 \pm 4.8 ]%.Both measurements are consistent with standard model predictions. These measurements are combined with all previous measurements to form new world averages of \ajpk\ and \ajppi .

hep-ex↗
arXiv2013

Charge Asymmetries in Semileptonic B Decays

I present measurements made by the D0 collaboration of the time-integrated flavor-specific semileptonic charge asymmetry in the decays of the Bs and Bd mesons that have undergone flavor mixing, asls and asld, using 10.4 fb^-1 of proton-antiproton collisions collected by the D0 detector during Run II at the Fermilab Tevatron Collider. The results are asls = [-1.12 \pm 0.74 (stat) \pm 0.17 (syst) ]% and asld = [0.68 \pm 0.45 (stat.) \pm 0.14 (syst.)]% which are the two most precise published results and are in agreement with standard model predictions. These results are combined with the like-sign dimuon charge asymmetry, aslb, and recent preliminary results from the LHCb and BaBar experiments to obtain new world averages.

hep-ex↗
arXiv2013

Sensitivity of LHC experiments to the $t\bar{t}H$ final state, with $H \rightarrow b\bar{b}$, at center of mass energy of 14 TeV

With the discovery of a Higgs-like particle in 2012, attention has now turned to measuring its properties, e.g., coupling to various bosonic and fermionic final states, its spin and parity, etc. In this note, we study the sensitivity of experiments at the LHC to its coupling to the top quark, by searching for the process pp $\rightarrow t\bar{t}H$, where the primary decay mode of the $H$ is $\rightarrow b\bar{b}$. In this paper, the $t\bar{t}$ system is detected in the dilepton final state. This study is performed assuming a center of mass energy of 14 TeV and integrated luminosities of 300 fb$^{-1}$ (with an average pileup ($μ$) of 50 additional collisions per bunch crossing) and 3000 fb$^{-1}$ (with $μ=140$). We include systematic uncertainties in production cross-sections as well as the more important experimental uncertainties. Preliminary studies indicate that we will observe the $t\bar{t}H$ final state with a significance of 2.4 and $\ge 5.3$ for the two luminosity scenarios, respectively; addition of other $t\bar{t}$ final states should increase the overall significance for observing $t\bar{t}H$.

hep-ex↗
arXiv2013

Measurement of $B$ Baryon Properties at CDF

We report on mass and mean life measurements of several ground state $b-$baryons, using 9.6 $\textrm{fb}^{-1}$ of data from $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV, and recorded with the Collider Detector at Fermilab. Data collected with triggers designed to collect events with $J/ψ\rightarrow μ^+ \, μ^-$ candidates and events with hadrons displaced from the beamline are used to measure the masses and lifetimes of $Λ_b, Ξ_b^-, Ξ_b^0$, and $Ω_b^-$. The first evidence for the process $Ω_b^- \rightarrow Ω_c^0 \, π^-$ is also shown. The results supersede our previous measurements of these quantities.

hep-ex↗
arXiv2013

QCD Sum Rule Analysis of Heavy Quarkonium Hybrids

We have studied the charmonium and bottomonium hybrid states with various $J^{PC}$ quantum numbers in QCD sum rules. At leading order in $α_s$, the two-point correlation functions have been calculated up to dimension six including the tri-gluon condensate and four-quark condensate. After performing the QCD sum rule analysis, we have confirmed that the dimension six condensates can stabilize the hybrid sum rules and allow the reliable mass predictions. We have updated the mass spectra of the charmonium and bottomonium hybrid states and identified that the negative-parity states with $J^{PC}=(0, 1, 2)^{-+}, 1^{--}$ form the lightest hybrid supermultiplet while the positive-parity states with $J^{PC}=(0, 1)^{+-}, (0, 1, 2)^{++}$ belong to a heavier hybrid supermultiplet.

hep-ph↗
arXiv2013

A Search for $t\bar{t}$ Resonances in Lepton Plus Jets Events with ATLAS using 14 fb$^{-1}$ of Proton-Proton Collisions at $\sqrt{s}$ = 8 TeV

Some Beyond the Standard Model theories predict new particles that decay predominantly into top-antitop quark pairs. A search for top-antitop quark resonances that decay into the lepton plus jets final state is carried out with the ATLAS experiment at the LHC using 14 fb$^{-1}$ of $\sqrt{s}$ = 8 TeV proton-proton collisions. The search considers both cases where all of the final state jets are isolated and where some or all of the top quark decay products are merged into a single jet. Mass exclusion limits at a 95% credibility level are set for two benchmark models, one predicting leptophobic topcolor Z' bosons and the other predicting Randall-Sundrum Kaluza-Klein gluons.

hep-ex↗
arXiv2013

ATLAS Searches for Beyond the Standard Model Higgs Bosons

The present status of ATLAS searches for Higgs bosons in extensions of the Standard Model (SM) is presented. This includes searches for the Higgs bosons of the Two-Higgs-Doublet Model (2HDM), the Minimal Supersymmetric Model (MSSM), the Next-to-Minimal Supersymmetric Model (NMSSM) and models with an invisibly decaying Higgs boson. A review of the phenomenology of the Higgs sectors of these models is given together with the search strategy and the resulting experimental constraints.

hep-ex↗
arXiv2013

Measurement of Inclusive Production of Light Charged Hadrons at BaBar

Inclusive hadron production cross sections in e+e-collisions shed light on the fundamental fragmentation and hadronization processes. We present measurements of the inclusive spectra of charged pions, kaons and protons in hadronic events at a center-of-mass energy of 10.54 \gev. These results are compared with theoretical predictions and the predictions of three hadronization models. Along with previous measurements at higher energies, they are also used to study the scaling properties of hadron production.

hep-ex↗
arXiv2013

Inclusive Deep Inelastic Scattering at High Q2 with Longitudinally Polarised Lepton Beams at HERA

Inclusive e^\pm p single and double differential cross sections for neutral (NC) and charged current (CC) deep inelastic scattering processes are measured with the H1 detector at HERA. The data were taken at a centre-of-mass energy of \sqrt{s} = 319 GeV with a total integrated luminosity of 327.8 pb^{-1} shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative four-momentum transfer squared, Q2, between 60 and 50 000 GeV2, and Bjorken x between 0.0008 and 0.65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function xF_3^{γZ}. A measurement of the structure function F_2^{γZ}, sensitive to parity violating effects in NC, is presented for the first time. The polarisation dependence of the CC total cross section is also measured. The new measurements are well described by a next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.

hep-ex↗
arXiv2013

The new radiation-hard optical links for the ATLAS pixel detector

The ATLAS detector is currently being upgraded with a new layer of pixel based charged particle tracking and a new arrangement of the services for the pixel detector. These upgrades require the replacement of the opto-boards previously used by the pixel detector. In this report we give details on the design and production of the new opto-boards.

physics.ins-det↗
arXiv2013

A Prototype of Wireless Power and Data Acquisition System for Large Detectors

A new prototype wireless data acquisition system has been developed with the intended application to read-out instrumentation systems having a large number of channels. In addition such system could be deployed in smaller detectors requiring increased mobility. The data acquisition and control system is based on 802.11n compliant hardware and protocols. In this paper we describe our case study with a single readout channel performed for a potential large detector containing photomultiplier tubes. The front-end circuitry, including a high-voltage power supply is powered wirelessly thus creating an all-wireless detector readout. The benchmarked performance of the prototype system and how a large scale implementation of the system might be realized are discussed.

physics.ins-det↗
arXiv2013

Study of ttH (H -> mu mu) in the three lepton channel at sqrt(s) = 14 TeV; A Snowmass white paper

The H -> mu mu signature provides excellent mass resolution for Higgs bosons, and is therefore an important Higgs boson decay channel despite the small dimuon branching ratio. We present an optimization of selection criteria in a search for trilepton ttH (H -> mu mu) events, in which the top quark pair decays semi-leptonically, at a simulated High Luminosity LHC (HL-LHC) running at 14 TeV. The study is performed with 3000 fb^(-1) of simulated data with an average pileup of < mu > = 140. In this ultimate HL-LHC data set, we find that ttH (H -> mu mu) will be a very difficult signature to observe due to the very small expected signal.

hep-ex↗
arXiv2013

Discovering the Significance of 5 sigma

We discuss the traditional criterion for discovery in Particle Physics of requiring a significance corresponding to at least 5 sigma; and whether a more nuanced approach might be better.

physics.data-an↗