Results on kaon, pion, and proton production in muon-proton scattering are presented for 1<Q2<80 GeV2 with an average Bjorken x of 0.033. The measured particle fractions for z>0.2(z=Phadν) are fπ=0.764±0.028, fK=0.187±0.042, and fp=0.049±0.013. The K±π± ratios as a function of z and pT2 are presented: The ratios increase with z, and with pT2 for z<0.3.
No description provided.
Searches for heavy long-lived charged particles are performed using a data sample of 19.8 fb$^{-1}$ from proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 8 TeV collected by the ATLAS detector at the Large Hadron Collider. No excess is observed above the estimated background and limits are placed on the mass of long-lived particles in various supersymmetric models. Long-lived tau sleptons in models with gauge-mediated symmetry breaking are excluded up to masses between 440 and 385 GeV for $\tan\beta$ between 10 and 50, with a 290 GeV limit in the case where only direct tau slepton production is considered. In the context of simplified LeptoSUSY models, where sleptons are stable and have a mass of 300 GeV, squark and gluino masses are excluded up to a mass of 1500 and 1360 GeV, respectively. Directly produced charginos, in simplified models where they are nearly degenerate to the lightest neutralino, are excluded up to a mass of 620 GeV. $R$-hadrons, composites containing a gluino, bottom squark or top squark, are excluded up to a mass of 1270, 845 and 900 GeV, respectively, using the full detector; and up to a mass of 1260, 835 and 870 GeV using an approach disregarding information from the muon spectrometer.
Cross-section upper limits as a function of the $\tilde{\tau}_1$ mass for direct $\tilde{\tau}_1$ production and three values of $\tan\beta$. Expected limits for $\tan\beta=10$ with $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties observed limits for three values of $\tan\beta$ and theoretical cross-section prediction for $\tan\beta=10$ with $\pm 1\sigma$ band.
Cross-section upper limits as a function of the $\tilde{\chi}_1$ mass for $\tilde{\tau}_1$ sleptons resulting from the decay of directly produced charginos and neutralinos in GMSB. Observed limits, expected limits for $\tan\beta=10$ with $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties and theoretical cross-section prediction (dominated by $\tilde{\chi}^0_1 \tilde{\chi}^+_1$ production) with $\pm 1\sigma$ uncertainty. Depending on the hypothesis and to a small extent on $\tan\beta$, in these models, the chargino mass is 210 to 260 GeV higher than the neutralino mass.
Cross-section upper limits for various chargino masses in stable-chargino models. Expected limit with $\pm 1\sigma$ and $\pm 2\sigma$ uncertainties, observed limit and theoretical cross-section prediction with $\pm 1\sigma$ uncertainties.
The production of a $W$ boson decaying to $e\nu$ or $\mu\nu$ in association with a $W$ or $Z$ boson decaying to two jets is studied using $4.6 \mathrm{fb}^{-1}$ of proton--proton collision data at $\sqrt{\rm{s}} = 7$ TeV recorded with the ATLAS detector at the LHC. The combined $WW+WZ$ cross section is measured with a significance of 3.4$\sigma$ and is found to be $68 \pm 7 \ \mathrm{(stat.)} \pm 19 \ \mathrm{(syst.)} \ pb$, in agreement with the Standard Model expectation of $61.1 \pm 2.2 \ \mathrm{pb}$. The distribution of the transverse momentum of the dijet system is used to set limits on anomalous contributions to the triple gauge coupling vertices and on parameters of an effective-field-theory model.
The total and fiducial cross sections for the production of W(LEPTON NU) W(JET JET) or W(LEPTON NU) Z(JET JET). The cross sections are the sum of the WW and WZ processes.
Several models of physics beyond the Standard Model predict neutral particles that decay into final states consisting of collimated jets of light leptons and hadrons (so-called "lepton jets"). These particles can also be long-lived with decay length comparable to, or even larger than, the LHC detectors' linear dimensions. This paper presents the results of a search for lepton jets in proton--proton collisions at the centre-of-mass energy of $\sqrt{s}$ = 8 TeV in a sample of 20.3 fb$^{-1}$ collected during 2012 with the ATLAS detector at the LHC. Limits on models predicting Higgs boson decays to neutral long-lived lepton jets are derived as a function of the particle's proper decay length.
Reconstruction efficiency of TYPE2 LJs as a function of the $p_{\mathrm{T}}$ of the $s_{d_{1}}$ for LJs with two $\gamma_{d}$'s for an \scalar mass of 2 GeV. For the $\gamma_{d}$, the kinematically allowed mass of 0.15 GeV is considered. The distributions for the other $s_{d_{1}}$ masses are very similar. The uncertainties are statistical only.
This Letter describes a model-independent search for the production of new resonances in photon + jet events using 20 inverse fb of proton--proton LHC data recorded with the ATLAS detector at a centre-of-mass energy of sqrt(s) = 8 TeV. The photon + jet mass distribution is compared to a background model fit from data; no significant deviation from the background-only hypothesis is found. Limits are set at 95% credibility level on generic Gaussian-shaped signals and two benchmark phenomena beyond the Standard Model: non-thermal quantum black holes and excited quarks. Non-thermal quantum black holes are excluded below masses of 4.6 TeV and excited quarks are excluded below masses of 3.5 TeV.
Invariant mass of the photon+jet pair for events passing the final selections. The number of observed events and the fit background estimates are given in each bin, where the fit estimates are rounded to the nearest integer.
The 95% CL upper limits on SIG*BR*A*EPSILON for a hypothetical signal with a Gaussian-shaped M(GAMMA JET) distribution as a function of the signal mass M(G) for four values of the relative width SIGMA(G) / M(G).
Acceptance (A), efficiency (EPSILON), cross-section (SIG) and limits in number of events for the quantum black hole (QBH) benchmark model, as a function of the threshold mass M(th). Uncertainties on the cross section are on the order of 1%. The limits include statistical uncertainties only. Expected limits include the 68% uncertainty band. Acceptance was calculated using parton-level quantities by imposing criteria that apply directly to kinematic selections (photon/jet |eta|, photon/jet transverse momentum, Delta(eta), Delta(R)). All other selections, which in general correspond to event and object quality criteria, were used to calculate the efficiency based on the events included in the acceptance.
The production of Ks0, Λ0, and Λ¯0 has been measured in deep-inelastic muon scattering at 225 GeV; decays into two charged hadrons were detected. Momentum distributions are compared to the inclusive charged-hadron distributions measured in the same experiment. The range of virtual-photon parameters covered is 0.4<Q2<50 GeV2 and 20<ν<210 GeV.
No description provided.
Measurements have been made of the inclusive scattering of 96, 147, and 219 GeV muons from hydrogen, and of 147 GeV muons from deuterium. Results are presented for the nucleon structure function F2(x,Q2) [≡νW2(x,Q2)] for 10<ν<200 GeV and 0.2<Q2<80 GeV2. The value of F2 rises with Q2 at small x, and falls with Q2 at large x, in agreement with the ideas of quantum chromodynamics. An average value of the ratio σLσT≡R=0.52±0.35 has been obtained for the region 0.003<x<0.10 and 0.4<Q2<30 GeV2. The values of F2 from this experiment have been combined with those from other charged-lepton scattering experiments to determine moments of the structure functions. The variation with Q2 of these moments is used to derive values for Λ, taking into account corrections up to second order in αs. The fit to the data is very good.
No description provided.
No description provided.
No description provided.
Results on the protron structure function, F2, are presented for 0.3<q2<80.0 GeV2 and 10<ν<200 GeV. The results support the conclusions of earlier work at 97 and 147 GeV that scaling is violated. A new value for R=σSσT=0.44±0.25 has been obtained using all the Fermilab proton measurements.
No description provided.
Measurements of fiducial and differential cross sections of Higgs boson production in the ${H \rightarrow ZZ ^{*}\rightarrow 4\ell}$ decay channel are presented. The cross sections are determined within a fiducial phase space and corrected for detection efficiency and resolution effects. They are based on 20.3 fb$^{-1}$ of $pp$ collision data, produced at $\sqrt{s}$=8 TeV centre-of-mass energy at the LHC and recorded by the ATLAS detector. The differential measurements are performed in bins of transverse momentum and rapidity of the four-lepton system, the invariant mass of the subleading lepton pair and the decay angle of the leading lepton pair with respect to the beam line in the four-lepton rest frame, as well as the number of jets and the transverse momentum of the leading jet. The measured cross sections are compared to selected theoretical calculations of the Standard Model expectations. No significant deviation from any of the tested predictions is found.
Measured differential fiducial cross sections in Higgs transverse momentum (second column). The given uncertainty includes statistical and systematic components. The third (fourth) column gives the theoretical prediction of Higgs production in the fiducial volume using Powheg Minlo HJ (HRes) for the ggF process, Powheg for the VBF process, and Pythia 8 for the VH and ttH process. The uncertainty includes PDF, scale, and branching fraction uncertainty. The fifth column gives the non-ggF prediction (total minus ggF). All predicted distributions were normalized to the best predicted inclusive Higgs production cross sections available at the time of the publication.
Measured differential fiducial cross sections in the absolute value of the Higgs rapidity (second column). The given uncertainty includes statistical and systematic components. The third (fourth) column gives the theoretical prediction of Higgs production in the fiducial volume using Powheg Minlo HJ (HRes) for the ggF process, Powheg for the VBF process, and Pythia 8 for the VH and ttH process. The uncertainty includes PDF, scale, and branching fraction uncertainty. The fifth column gives the non-ggF prediction (total minus ggF). All predicted distributions were normalized to the best predicted inclusive Higgs production cross sections available at the time of the publication.
Measured differential fiducial cross sections in m34, which corresponds to the invariant mass of the off-shell Z boson (second column). The given uncertainty includes statistical and systematic components. The third column gives the theoretical prediction of Higgs production in the fiducial volume using Powheg Minlo HJ for the ggF process, Powheg for the VBF process, and Pythia 8 for the VH and ttH process. The uncertainty includes PDF, scale, and branching fraction uncertainty. The fourth column gives the non-ggF prediction (total minus ggF). All predicted distributions were normalized to the best predicted inclusive Higgs production cross sections available at the time of the publication.
A search for scalar particles decaying via narrow resonances into two photons in the mass range $65-600$ GeV is performed using 20.3 fb$^{-1}$ of $\sqrt{s}$ = 8 TeV $pp$ collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95 % confidence level on the production cross-section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches.
Forum