Results 1  10
of
552
RenormalizationGroup Improved Calculation of the B → Xsγ Branching Ratio (hepph/0408179
"... Using results on softcollinear factorization for inclusive Bmeson decay distributions, a systematic study of the partial B → Xsγ decay rate with a cut Eγ ≥ E0 on photon energy is performed. For values of E0 below about 1.9 GeV, the rate can be calculated without reference to shape functions using ..."
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Using results on softcollinear factorization for inclusive Bmeson decay distributions, a systematic study of the partial B → Xsγ decay rate with a cut Eγ ≥ E0 on photon energy is performed. For values of E0 below about 1.9 GeV, the rate can be calculated without reference to shape functions using a multiscale operator product expansion (MSOPE). The transition from the shapefunction region to the MSOPE region is studied analytically. The resulting prediction for the B → Xsγ branching ratio depends on three large scales: mb, √ mb∆, and ∆ = mb − 2E0. Logarithms associated with these scales are resummed at nexttonexttoleading logarithmic order. While power corrections in ΛQCD/ ∆ turn out to be small, the sensitivity to the scale ∆ ≈ 1.1 GeV (for E0 ≈ 1.8 GeV) introduces significant perturbative uncertainties, which so far have been ignored. The new theoretical prediction for the B → Xsγ branching ratio with +0.31 +0.32 Eγ ≥ 1.8 GeV is Br(B → Xsγ) = (3.38 −0.42 −0.30) × 10−4, where the first error is an estimate of perturbative uncertainties and the second one reflects uncertainties in input
Reconstructing sparticle mass spectra using hadronic decays,” JHEP 0705
, 2007
"... Most sparticle decay cascades envisaged at the Large Hadron Collider (LHC) involve hadronic decays of intermediate particles. We use stateofthe art techniques based on the K ⊥ jet algorithm to reconstruct the resulting hadronic final states for simulated LHC events in a number of benchmark supersy ..."
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Cited by 7 (1 self)
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Most sparticle decay cascades envisaged at the Large Hadron Collider (LHC) involve hadronic decays of intermediate particles. We use stateofthe art techniques based on the K ⊥ jet algorithm to reconstruct the resulting hadronic final states for simulated LHC events in a number of benchmark supersymmetric scenarios. In particular, we show that a general method of selecting preferentially boosted massive particles such as W ±,Z 0 or Higgs bosons decaying to jets, using subjets found by the K ⊥ algorithm, suppresses QCD backgrounds and thereby enhances the observability of signals that would otherwise be indistinct. Consequently, measurements of the supersymmetric mass spectrum at the percent level can be obtained from cascades including the hadronic decays of such massive intermediate bosons.
Black Holes and Quantum Gravity at the LHC
 JHEP
"... We argue that the highly studied black hole signatures based on thermal multiparticle final states are very unlikely and only occur in a very limited parameter regime if at all. However, we show that if the higherdimensional quantum gravity scale is low, it should be possible to study quantum gravi ..."
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We argue that the highly studied black hole signatures based on thermal multiparticle final states are very unlikely and only occur in a very limited parameter regime if at all. However, we show that if the higherdimensional quantum gravity scale is low, it should be possible to study quantum gravity in the context of higher dimensions through detailed compositenesstype searches. 1
Heavy flavour phenomenology from lattice QCD
"... The focus of this report is the lattice calculation of hadronic parameters relevant to heavy flavour phenomenology. I will review recent results and the current status of studies of the B and D decay constants, semileptonic decay form factors, B 0 − ¯B 0 mixing, and determinations of the quark masse ..."
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The focus of this report is the lattice calculation of hadronic parameters relevant to heavy flavour phenomenology. I will review recent results and the current status of studies of the B and D decay constants, semileptonic decay form factors, B 0 − ¯B 0 mixing, and determinations of the quark masses mc and mb. Some studies of heavy flavour observables have used current lattice results to derive Standard Model predictions that disagree with experimental measurements. That is the case of sin(2β) and fDs. This report discusses efforts to resolve the origin of those discrepancies from the lattice side.
Improved description of charged Higgs boson production at hadron colliders
 JHEP 0412 (2004) 050 [arXiv:hepph/0409094
"... Abstract: We present a new method for matching the two twinprocesses gb → H ± t and gg → H ± tb in Monte Carlo event generators. The matching is done by defining a doublecounting term, which is used to generate events that are subtracted from the sum of these two twinprocesses. In this way we get ..."
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Cited by 3 (2 self)
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Abstract: We present a new method for matching the two twinprocesses gb → H ± t and gg → H ± tb in Monte Carlo event generators. The matching is done by defining a doublecounting term, which is used to generate events that are subtracted from the sum of these two twinprocesses. In this way we get a smooth transition between the collinear region of phase space, which is best described by gb → H ± t, and the hard region, which requires the use of the gg → H ± tb process. The resulting differential distributions show large differences compared to both the gb → H ± t and gg → H ± tb processes illustrating the necessity to use matching when tagging the accompanying bjet.
Search for Events with an Isolated Lepton and Missing Transverse Momentum and a Measurement of W Production at HERA
"... Events with high energy isolated electrons, muons or tau leptons and missing transverse momentum are studied using the full e ± p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb−1. Within the Standard Model, events with isolated leptons and mis ..."
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Events with high energy isolated electrons, muons or tau leptons and missing transverse momentum are studied using the full e ± p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb−1. Within the Standard Model, events with isolated leptons and missing transverse momentum mainly originate from the production of single W bosons. The total single W boson production cross section is measured as 1.14 ± 0.25 (stat.) ± 0.14 (sys.) pb, in agreement with the Standard Model expectation. The data are also used to establish limits on the WWγ gauge couplings and
Surveying the Phenomenology of General Gauge Mediation,” arXiv:0812.2051 [hepph
"... I explore the phenomenology, constraints and tuning for several weakly coupled implementations of multiparameter gauge mediation and compare to minimal gauge mediation. The low energy spectra are distinct from that of minimal gauge mediation; a wide range of NLSPs is found and spectra are significa ..."
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I explore the phenomenology, constraints and tuning for several weakly coupled implementations of multiparameter gauge mediation and compare to minimal gauge mediation. The low energy spectra are distinct from that of minimal gauge mediation; a wide range of NLSPs is found and spectra are significantly compressed, thus tunings may Gauge mediation is a predictive and flavor blind communication mechanism for SUSY breaking [1]. The earliest and simplest implementation of minimal gauge mediation involved communication of SUSY breaking from the hidden sector through a single set of vector like messengers charged under standard
Testing neutrino masses in little Higgs models via discovery of doubly charged Higgs at LHC
, 705
"... We have investigated the possibility of direct tests of little Higgs models incorporating triplet Higgs neutrino mass mechanism at LHC experiments. We have performed Monte Carlo studies of DrellYan pair production of doubly charged Higgs boson Φ ++ followed by its leptonic decays whose branching ra ..."
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We have investigated the possibility of direct tests of little Higgs models incorporating triplet Higgs neutrino mass mechanism at LHC experiments. We have performed Monte Carlo studies of DrellYan pair production of doubly charged Higgs boson Φ ++ followed by its leptonic decays whose branching ratios are fixed from the neutrino oscillation data. We propose appropriate selection rules for the fourlepton signal, including reconstructed taus, which are optimized for the discovery of Φ ++ with the lowest LHC luminosity. As the Standard Model background can be effectively eliminated, an important aspect of our study is the correct statistical treatment of the LHC discovery potential. Adding detection efficiencies and measurement errors to the Monte Carlo analyses, Φ ++ can be discovered up to the mass 250 GeV in the first year of LHC, and 700 GeV mass is reachable for the integrated luminosity L = 30 fb −1. The main motivation of the Large Hadron Collider (LHC) experiment is to reveal the secrets of electroweak symmetry breaking. If the light standard model (SM) Higgs boson H will be discovered, the question arises what stabilizes its mass against the Planck scale quadratically
Azimuthal decorrelations between QCD jets at all orders, Phys
 Lett. B
"... A quantity that promises to reveal important information on perturbative and nonperturbative QCD dynamics is the azimuthal decorrelation between jets in different hard processes. In order to access this information fixedorder NLO predictions need to be supplemented by resummation of logarithmic te ..."
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A quantity that promises to reveal important information on perturbative and nonperturbative QCD dynamics is the azimuthal decorrelation between jets in different hard processes. In order to access this information fixedorder NLO predictions need to be supplemented by resummation of logarithmic terms which are large in the region where the jets are nearly backtoback in azimuth. In the present letter we carry out this resummation to nextto–leading logarithmic accuracy explaining the important role played by the recombination scheme in general resummations for such jet One of the most commonly measured jet observables in experimental QCD studies is the azimuthal decorrelation ∆φ between hard finalstate jets. When compared to theoretical estimates of the same, this quantity is expected to provide valuable information both on QCD parameters (strong coupling, pdfs) as well as dynamics in the near backto–
Dijet rates with symmetric Et cuts
 J. High Energy Phys
"... Preprint typeset in JHEP style. PAPER VERSION hepph/0312108 ..."
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Preprint typeset in JHEP style. PAPER VERSION hepph/0312108