Phenomenology of event shapes at hadron colliders

Banfi, Andrea; Salam, Gavin P.; Zanderighi, Giulia

doi:10.1007/jhep06(2010)038

Cited by 199 publications

(241 citation statements)

References 133 publications

(322 reference statements)

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“…For event shape observables such as beam thrust [102,127,128], transverse thrust [101,129], and E T [130][131][132] the importance of this type of diagram for the violation of factorization was first discussed in [103]. This diagram has also been computed numerically for a double spin asymmetry beam thrust observable, demonstrating explicitly that it is nonzero [104].…”

Section: Jhep08(2016)025mentioning

confidence: 99%

An effective field theory for forward scattering and factorization violation

Rothstein

Stewart

2016

J. High Energ. Phys.

140

291

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Starting with QCD, we derive an effective field theory description for forward scattering and factorization violation as part of the soft-collinear effective field theory (SCET) for high energy scattering. These phenomena are mediated by long distance Glauber gluon exchanges, which are static in time, localized in the longitudinal distance, and act as a kernel for forward scattering where |t| s. In hard scattering, Glauber gluons can induce corrections which invalidate factorization. With SCET, Glauber exchange graphs can be calculated explicitly, and are distinct from graphs involving soft, collinear, or ultrasoft gluons. We derive a complete basis of operators which describe the leading power effects of Glauber exchange. Key ingredients include regulating light-cone rapidity singularities and subtractions which prevent double counting. Our results include a novel all orders gauge invariant pure glue soft operator which appears between two collinear rapidity sectors. The 1-gluon Feynman rule for the soft operator coincides with the Lipatov vertex, but it also contributes to emissions with ≥ 2 soft gluons. Our Glauber operator basis is derived using tree level and one-loop matching calculations from full QCD to both SCET II and SCET I . The one-loop amplitude's rapidity renormalization involves mixing of color octet operators and yields gluon Reggeization at the amplitude level. The rapidity renormalization group equation for the leading soft and collinear functions in the forward scattering cross section are each given by the BFKL equation. Various properties of Glauber gluon exchange in the context of both forward scattering and hard scattering factorization are described. For example, we derive an explicit rule for when eikonalization is valid, and provide a direct connection to the picture of multiple Wilson lines crossing a shockwave. In hard scattering operators Glauber subtractions for soft and collinear loop diagrams ensure that we are not sensitive to the directions for soft and collinear Wilson lines. Conversely, certain Glauber interactions can be absorbed into these soft and collinear Wilson lines by taking them to be in specific directions. We also discuss criteria for factorization violation.

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Section: Jhep08(2016)025mentioning

confidence: 99%

An effective field theory for forward scattering and factorization violation

Rothstein

Stewart

2016

J. High Energ. Phys.

140

291

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“…The restriction to the transverse plane avoids the bias from the boost along the beam axis [22]. It is defined for a unit transverse vectorn which minimizes the ratio below:…”

Section: Transverse Spherocitymentioning

confidence: 99%

Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia

2015

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The pp collisions have been studied for a long time, however, there are still some effects which are not completely understood, such as the long range angular correlations and the flow patterns in high multiplicity events, which were recently discovered at the LHC. In a recent work it was demonstrated that in Pythia 8, multi-parton interactions and color reconnection can give some of the observed effects similar to the collective flow well known from heavy-ion collisions. Now using the same model, a study based on mid-rapidity charged hadron transverse spherocity is presented. The main purpose of this work is to show that a differential study combining multiplicity and event shapes opens the possibility to understand better the features of data, specially at high multiplicity.

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“…The correlation of in the azimuthal angle should also be reflected in the global structure of softer tracks, which do not give rise to resolved jets. It is precisely the hadronic energy flow which is captured by event shape observables in theoretically favorable way [41], turning them into natural candidates to be considered among the CP-discriminative observables in the context of CP analyses. From a perturbative QCD point of view, the phenomenology of event shapes [41] possesses a number of advantages over "traditional" jetbased observables.…”

Section: Introductionmentioning

confidence: 99%

Measuring Higgs $ \mathcal{C}\mathcal{P} $ and couplings with hadronic event shapes

Englert

Spannowsky

Takeuchi

2012

J. High Energ. Phys.

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Experimental falsification or validation of the Standard Model of Particle Physics involves the measurement of the CP quantum number and couplings of the Higgs boson. Both Atlas and Cms have reported an SM Higgs-like excess around mH = 125 GeV. In this mass range the CP properties of the Higgs boson can be extracted from an analysis of the azimuthal angle distribution of the two jets in pp → Hjj events. This channel is also important to measure the couplings of the Higgs boson to electroweak gauge bosons and fermions, hereby establishing the exceptional role of the Higgs boson in the Standard Model. Instead of exploiting the jet angular correlation, we show that hadronic event shapes exhibit substantial discriminative power to separate a CP even from a CP odd Higgs. Some event shapes even show an increased sensitivity to the Higgs CP compared to the azimuthal angle correlation. Constraining the Higgs couplings via a separation of the weak boson fusion and the gluon fusion Higgs production modes can be achieved applying similar strategies.

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Phenomenology of event shapes at hadron colliders

Cited by 199 publications

References 133 publications

An effective field theory for forward scattering and factorization violation

An effective field theory for forward scattering and factorization violation

Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia

Measuring Higgs $ \mathcal{C}\mathcal{P} $ and couplings with hadronic event shapes

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