1,464 research outputs found
The SU(3)-invariant sector of new maximal supergravity
No full textWe investigate the SU(3)-invariant sector of the one-parameter family of SO(8) gauged maximal supergravities that has been recently discovered. To this end, we construct the N = 2 truncation of this theory and analyse its full vacuum structure. The number of critical point is doubled and includes new N = 0 and N = 1 branches. We numerically exhibit the parameter dependence of the location and cosmological constant of all extrema. Moreover, we provide their analytic expressions for cases of special interest. Finally, while the mass spectra are found to be parameter independent in most cases, we show that the novel non-supersymmetric branch with SU(3) invariance provides the first counterexample to this.
Measurement of the differential cross-section of B+ meson production in pp collisions at root s=7 TeV at ATLAS
No full textThe production cross-section of B+ mesons is measured as a function of transverse momentum p T and rapidity y in proton-proton collisions at centre-of-mass energy root s = 7 TeV, using 2.4 fb(-1) of data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9 GeV < p(T) < 120 GeV and vertical bar y vertical bar < 2.25, are compared to next-to-leading-order theoretical predictions
What is the or irreducible background to the light Higgs boson searches at LHC?
No full textThe W b anti-b, Z b anti-b and t anti-t b anti-b production at LHC are irreducible backgrounds for possible observability of the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) light Higgs boson respectively in the associated WH, ZH and t anti-t H production followed by the H -> b anti-b decay. We present a comparison of the background estimates as obtained with (a) complete massive matrix element implemented in AcerMC Monte Carlo generator and (b) PYTHIA implementation of the inclusive W, Z, and t anti-t production, followed by the parton showering mechanism. Both approaches lead to a production of the final state of interest, but differ in the approximations used. We concentrate on the comparison of these approaches for the background to the light Higgs boson searches at LHC
Search for W ' -> t(b)over-bar in the lepton plus jets final state in proton-proton collisions at a centre-of-mass energy of root s=8 TeV with the ATLAS detector
No full textA search for new charged massive gauge bosons, called W', is performed with the ATLAS detector at the LHC, in proton-proton collisions at a centre-of-mass energy of root s = 8 TeV, using a dataset corresponding to an integrated luminosity of 20.3 fb(-1). This analysis searches for W' bosons in the W' -> t (b) over tilde decay channel in final states with electrons or muons, using a multivariate method based on boosted decision trees. The search covers masses between 0.5 and 3.0 TeV, for right-handed or left-handed W' bosons. No significant deviation from the Standard Model expectation is observed and limits are set on the W' -> t (b) over bar cross-section times branching ratio and on the W'-boson effective couplings as a function of the W'-boson mass using the CLs procedure. For a left-handed (right-handed) W' boson, masses below 1.70 (1.92) TeV are excluded at 95% confidence level.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1016/j.physletb.2015.02.051</p
Measurement of the production cross section of jets in association with a Z boson in pp collisions at √s=7 TeV with the ATLAS detector
No full textMeasurements of the production of jets of particles in association with a Z boson in pp collisions at s√=7 TeV are presented, using data corresponding to an integrated luminosity of 4.6 fb−1 collected by the ATLAS experiment at the Large Hadron Collider. Inclusive and differential jet cross sections in Z events, with Z decaying into electron or muon pairs, are measured for jets with transverse momentum p T > 30 GeV and rapidity |y| < 4.4. The results are compared to next-to-leading-order perturbative QCD calculations, and to predictions from different Monte Carlo generators based on leading-order and next-to-leading-order matrix elements supplemented by parton showers
Measurement of the top quark mass with the template method in the t<span style="text-decoration: overline">t</span> →lepton+jets channel using ATLAS data
No full textContains fulltext :
103516.pdf (Publisher’s version ) (Open Access
Measurement of the b-hadron production cross section using decays to D∗ +μ −X final states in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV with the ATLAS detector
No full textThe b-hadron production cross section is measured with the ATLAS detector in pp collisions at
√<span style="text-decoration:overline">s</span>=7 TeV, using 3.3 pb−1
of integrated luminosity, collected during the 2010 LHC run. The b-hadrons
are selected by partially reconstructing D∗+μ
−X final states. Differential cross sections are measured as
functions of the transverse momentum and pseudorapidity. The measured production cross section for a
b-hadron withpT
>9 GeV and |η|<2.5 is 32.7±0.8(stat.)+4.5
−6.8
(syst.) µb, higher than the next-to-leadingorder QCD predictions but consistent within the experimental and theoretical uncertainties
Measurement of the rate of b anti-b b anti-b events in hadronic Z decays and the extraction of the gluon splitting into b anti-b
No full textThe rate was measured using about hadronic decays collected by the DELPHI experiment in 1994 and 1995. Events were forced into 3-jets with and a b-tag was required for every jet. The rate was measured to be: where the invariant mass of every system is above twice the b quark mass. Using the value of the probability of secondary production of a pair from a gluon per hadronic decay, , was extracted and found to be:
The gg, qqbar -> Z/gamma*(-> l l ) b bbar process: matrix element implementation to PYTHIA 6.1
No full textThe Z/gamma* (--> l l) b bbar production at LHC is a potentially severe background for observability of different Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) Higgs boson(s) decay channels. Here we describe implementation of the massive matrix elements for the gg, q qbar --> Z/gamma* (--> l l) b bbar processes into PYTHIA 6.1 Monte Carlo
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