scholarly journals One-loop jet functions by geometric subtraction

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Avanish Basdew-Sharma ◽  
Franz Herzog ◽  
Solange Schrijnder van Velzen ◽  
Wouter J. Waalewijn
Keyword(s):  
Power Law ◽  
Cross Sections ◽  
Azimuthal Angle ◽  
Final State ◽  
Subtraction Scheme ◽  
Finite Term ◽  
Analytic Integration ◽  
Soft Limit ◽  
The One ◽  
Crucial Ingredient

Abstract In factorization formulae for cross sections of scattering processes, final-state jets are described by jet functions, which are a crucial ingredient in the resummation of large logarithms. We present an approach to calculate generic one-loop jet functions, by using the geometric subtraction scheme. This method leads to local counterterms generated from a slicing procedure; and whose analytic integration is particularly simple. The poles are obtained analytically, up to an integration over the azimuthal angle for the observable- dependent soft counterterm. The poles depend only on the soft limit of the observable, characterized by a power law, and the finite term is written as a numerical integral. We illustrate our method by reproducing the known expressions for the jet function for angularities, the jet shape, and jets defined through a cone or kT algorithm. As a new result, we obtain the one-loop jet function for an angularity measurement in e+e− collisions, that accounts for the formally power-suppressed but potentially large effect of recoil. An implementation of our approach is made available as the GOJet Mathematica package accompanying this paper.

Spectral profiles of two-photon absorption: Coherent versus two-step two-photon absorption

2004 ◽  
Vol 846 ◽  
Author(s):  
S. Polyutov ◽  
I. Minkov ◽  
F. Gel'mukhanov ◽  
K. Kamada ◽  
A. Baev ◽  
...  
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Photon Absorption ◽  
Final State ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Spectral Bands ◽  
Spectral Profiles ◽  
The One ◽  
Spectral Shapes

ABSTRACTWe present a theory of two-photon absorption in solutions which addresses the formation of spectral shapes taking account of the vibrational degrees of freedom. The theory is used to rationalize observed differences between spectral shapes of one- and two-photon absorption. We elaborate on two underlying causes, one trivial and one non-trivial, behind these differences. The first refers simply to the fact that the set of excited electronic states constituting the spectra will have different relative cross sections for one-and two- photon absorption. The second reason is that the two-step and coherent two-photon absorption processes are competing, making the one-and two-photon spectral bands different even considering a single final state. The theory is applied to the N-101 molecule [di-phenyl-amino-nitro-stilbene] which was recently studied experimentally in the paper [ T.-C. Lin, G.S. He, P.N. Prasad, and L.-S. Tan, J. Mater. Chem., 14, 982, 2004.]

scholarly journals Reconciling Higgs physics and pseudo-Nambu-Goldstone dark matter in the S2HDM using a genetic algorithm

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Thomas Biekötter ◽  
María Olalla Olea-Romacho
Keyword(s):  
Genetic Algorithm ◽  
Dark Matter ◽  
Cross Sections ◽  
Direct Detection ◽  
Scalar Potential ◽  
Higgs Sector ◽  
Higgs Doublet ◽  
Final State ◽  
The One ◽  
Relic Abundance

Abstract We investigate a possible realization of pseudo-Nambu-Goldstone (pNG) dark matter in the framework of a singlet-extended 2 Higgs doublet model (S2HDM). pNG dark matter gained attraction due to the fact that direct-detection constraints can be avoided naturally because of the momentum-suppressed scattering cross sections, whereas the relic abundance of dark matter can nevertheless be accounted for via the usual thermal freeze-out mechanism. We confront the S2HDM with a multitude of theoretical and experimental constraints, paying special attention to the theoretical limitations on the scalar potential, such as vacuum stability and perturbativity. In addition, we discuss the complementarity between constraints related to the dark matter sector, on the one hand, and to the Higgs sector, on the other hand. In our numerical discussion we explore the Higgs funnel region with dark matter masses around 60 GeV using a genetic algorithm. We demonstrate that the S2HDM can easily account for the measured relic abundance while being in agreement with all relevant constraints. We also discuss whether the so-called center-of-galaxy excesses can be accommodated, possibly in combination with a Higgs boson at about 96 GeV that can be the origin of the LEP- and the CMS-excess observed at this mass in the b$$ \overline{b} $$ b ¯ -quark and the diphoton final state, respectively.

scholarly journals Trijets in $$k_\mathrm{T}$$-factorisation: matrix elements vs parton shower

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
H. Van Haevermaet ◽  
A. Van Hameren ◽  
P. Kotko ◽  
K. Kutak ◽  
P. Van Mechelen
Keyword(s):  
Cross Sections ◽  
Azimuthal Angle ◽  
Distribution Functions ◽  
Matrix Elements ◽  
Parton Distribution Functions ◽  
Initial State ◽  
Final State ◽  
Proton Proton ◽  
Shell Matrix ◽  
State Radiation

Abstract We study 3-jet event topologies in proton-proton collisions at a centre-of-mass energy of $$\sqrt{s} = 13 \mathrm{\ TeV}$$s=13TeV in a configuration, where one jet is present in the central pseudorapidity region ($$|\eta | < 2.0$$|η|<2.0) while two other jets are in a more forward (same hemisphere) area ($$|\eta | > 2.0$$|η|>2.0). We compare various parton level predictions using: collinear factorisation, $$k_\mathrm{T}$$kT-factorisation with fully off-shell matrix elements and the hybrid framework. We study the influence of different parton distribution functions, initial state radiation, final state radiation, and hadronisation. We focus on differential cross sections as a function of azimuthal angle difference between the leading dijet system and the third jet, which is found to have excellent sensitivity to the physical effects under study.

scholarly journals Analytic integration of soft and collinear radiation in factorised QCD cross sections at NNLO

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Lorenzo Magnea ◽  
Giovanni Pelliccioli ◽  
Chiara Signorile-Signorile ◽  
Paolo Torrielli ◽  
Sandro Uccirati
Keyword(s):  
Phase Space ◽  
Cross Sections ◽  
Final State ◽  
Careful Choice ◽  
Singular Terms ◽  
Analytic Integration ◽  
Integration Techniques

Abstract Within the framework of local analytic sector subtraction, we present the full analytic integration of double-real and real-virtual local infrared counterterms that enter NNLO QCD computations with any number of massless final-state partons. We show that a careful choice of phase-space mappings leads to simple analytic results, including non-singular terms, that can be obtained with conventional integration techniques.

scholarly journals Charmed and bottomed hadronic cross sections from a statistical model

2020 ◽  
Vol 56 (9) ◽  
Author(s):  
Gábor Balassa ◽  
György Wolf
Keyword(s):  
Statistical Model ◽  
Energy Range ◽  
Cross Sections ◽  
Heavy Quarks ◽  
Open Charm ◽  
Low Energy ◽  
Final State ◽  
Proton Antiproton ◽  
Proton Proton

Abstract In this work, we extended our statistical model with charmed and bottomed hadrons, and fit the quark creational probabilities for the heavy quarks, using low energy inclusive charmonium and bottomonium data. With the finalized fit for all the relevant types of quarks (up, down, strange, charm, bottom) at the energy range from a few GeV up to a few tens of GeV’s, the model is now considered complete. Some examples are also given for proton–proton, pion–proton, and proton–antiproton collisions with charmonium, bottomonium, and open charm hadrons in the final state.

scholarly journals Collinear expansion for color singlet cross sections

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Markus A. Ebert ◽  
Bernhard Mistlberger ◽  
Gherardo Vita
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross ◽  
Gluon Fusion ◽  
Building Blocks ◽  
Color Singlet ◽  
Final State ◽  
Beam Function ◽  
Kinematic Limit ◽  
State Radiation

Abstract We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.

scholarly journals Charged lepton flavor violation at the EIC

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Vincenzo Cirigliano ◽  
Kaori Fuyuto ◽  
Christopher Lee ◽  
Emanuele Mereghetti ◽  
Bin Yan
Keyword(s):  
Cross Sections ◽  
Charged Lepton ◽  
Hadron Collider ◽  
Effective Field ◽  
Background Suppression ◽  
Lepton Flavor Violation ◽  
Final State ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Discovery Potential

Abstract We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel ep→τX, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various τ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in τ-e transitions, we study the sensitivity of other probes of this physics across a broad range of energy scales, from pp→eτX at the Large Hadron Collider to decays of B mesons and τ leptons, such as τ→eγ, τ→eℓ+ℓ−, and crucially the hadronic modes τ→eY with Y∈π, K, ππ, Kπ, …. We find that electroweak dipole and four-fermion semi-leptonic operators involving light quarks are already strongly constrained by τ decays, while operators involving the c and b quarks present more promising discovery potential for the EIC. An analysis of three models of leptoquarks confirms the expectations based on the SMEFT results. We also identify future directions needed to maximize the reach of the EIC in CLFV searches: these include an optimization of the τ tagger in hadronic channels, an exploration of background suppression through tagging b and c jets in the final state, and a global fit by turning on all SMEFT couplings, which will likely reveal new discovery windows for the EIC.

scholarly journals Blocks Size Frequency Distribution in the Enceladus Tiger Stripes Area: Implications on Their Formative Processes

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 82
Author(s):  
Maurizio Pajola ◽  
Alice Lucchetti ◽  
Lara Senter ◽  
Gabriele Cremonese
Keyword(s):  
Frequency Distribution ◽  
Power Law ◽  
Size Frequency Distribution ◽  
Surface Stresses ◽  
Size Frequency ◽  
The One ◽  
Power Law Index ◽  
Comet 67P ◽  
South Polar ◽  
Degree Of Fragmentation

We study the size frequency distribution of the blocks located in the deeply fractured, geologically active Enceladus South Polar Terrain with the aim to suggest their formative mechanisms. Through the Cassini ISS images, we identify ~17,000 blocks with sizes ranging from ~25 m to 366 m, and located at different distances from the Damascus, Baghdad and Cairo Sulci. On all counts and for both Damascus and Baghdad cases, the power-law fitting curve has an index that is similar to the one obtained on the deeply fractured, actively sublimating Hathor cliff on comet 67P/Churyumov-Gerasimenko, where several non-dislodged blocks are observed. This suggests that as for 67P, sublimation and surface stresses favor similar fractures development in the Enceladus icy matrix, hence resulting in comparable block disaggregation. A steeper power-law index for Cairo counts may suggest a higher degree of fragmentation, which could be the result of localized, stronger tectonic disruption of lithospheric ice. Eventually, we show that the smallest blocks identified are located from tens of m to 20–25 km from the Sulci fissures, while the largest blocks are found closer to the tiger stripes. This result supports the ejection hypothesis mechanism as the possible source of blocks.

scholarly journals Method for assessment of matching of total ankle joint endoprostheses based on CT data

2020 ◽  
Vol 6 (3) ◽  
pp. 396-397
Author(s):  
Heiner Martin ◽  
Josephine Wittmüß ◽  
Thomas Mittlmeier ◽  
Niels Grabow
Keyword(s):  
Cross Sections ◽  
Spline Functions ◽  
Moments Of Inertia ◽  
Cad System ◽  
Principal Moments Of Inertia ◽  
Principal Axes ◽  
Ct Data ◽  
The One ◽  
Relative Differences ◽  
Systemic Design

AbstractThe investigation of matching of endoprosthesis tibial components to the bone cross section is of interest for the manufacturer as well as for the surgeon. On the one hand, a systemic design of the prosthesis and the assortment is possible, on the other hand, a better matching implantation is enabled on the basis of experience of this study. CT sections were segmented manually using a CAD system and fitted by spline functions, then superseded with cross sections of the tibial component of a modified Hintermann H3 prosthesis. The principal moments of inertia, the direction of the principal axes and the area of the section were evaluated. Based on the relative differences of the principal moments of inertia, recommendations for application of the different prosthesis size and its selection with the surgery can be made.

scholarly journals Dual subtractions

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Renato Maria Prisco ◽  
Francesco Tramontano
Keyword(s):  
Field Theory ◽  
Quantum Field ◽  
Matrix Elements ◽  
Leading Order ◽  
Initial State ◽  
Final State ◽  
Dual Representation ◽  
Subtraction Scheme ◽  
Theoretical Predictions ◽  
Perturbative Quantum

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.

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