scholarly journals Improving the understanding of jet grooming in perturbation theory

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Andrew J. Larkoski
Keyword(s):  
Perturbation Theory ◽  
Phase Space ◽  
Cross Section ◽  
Power Counting ◽  
Numerical Results ◽  
Factorization Theorem ◽  
Jet Physics ◽  
Leading Order ◽  
Physics Program ◽  
Jet Observables

Abstract Jet grooming has emerged as a necessary and powerful tool in a precision jet physics program. In this paper, we present three results on jet grooming in perturbation theory, focusing on heavy jet mass in e+e−→ hadrons collisions, groomed with the modified mass drop tagger. First, we calculate the analytic cross section at leading-order. Second, using the leading-order result and numerical results through next-to-next-to-leading order, we show that cusps in the distribution on the interior of phase space at leading-order are softened at higher orders. Finally, using analytic and numerical results, we show that terms that violate the assumptions of the factorization theorem for groomed jet mass are numerically much smaller than expected from power counting. These results provide important information regarding the convergence of perturbation theory for groomed jet observables and reliable estimates for residual uncertainties in a precision calculation.

scholarly journals ADVANCES IN A FIELD-THEORETIC UNDERSTANDING OF PION PRODUCTION IN NUCLEON–NUCLEON COLLISIONS

2007 ◽  
Vol 22 (02n03) ◽  
pp. 591-595 ◽  
Author(s):  
VADIM LENSKY ◽  
JOHANN HAIDENBAUER ◽  
CHRISTOPH HANHART ◽  
VADIM BARU ◽  
ALEXANDER KUDRYAVTSEV ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Cross Section ◽  
Chiral Perturbation Theory ◽  
Pion Production ◽  
Nucleon Nucleon ◽  
Leading Order ◽  
Production Amplitude ◽  
Chiral Perturbation ◽  
Phenomenological Studies ◽  
The Cross

We study the production amplitude for the reaction NN → NNπ up to next-to-leading order in chiral perturbation theory. We show that the irreducible chiral loops at this order exactly cancel those terms that arise from the off-shell parts of the πN rescattering vertex. This cancellation is required for formal consistency of the whole scheme. The net effect of the inclusion of all next-to-leading order loops is to enhance the leading rescattering amplitude by a factor of 4/3 compared to phenomenological studies, bringing its contribution to the cross section for pp → dπ+ close to the experimental value.

scholarly journals NLO QCD and EW corrections to vector-boson scattering into ZZ at the LHC

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Ansgar Denner ◽  
Robert Franken ◽  
Mathieu Pellen ◽  
Timo Schmidt
Keyword(s):  
Phase Space ◽  
Cross Section ◽  
Vector Boson ◽  
Z Bosons ◽  
The Other ◽  
Leading Order ◽  
Order Analysis ◽  
Other Hand ◽  
Vector Boson Scattering ◽  
Take All

Abstract We present the first calculation of the full next-to-leading-order electroweak and QCD corrections for vector-boson scattering (VBS) into a pair of Z bosons at the LHC. We consider specifically the process pp → e+e−μ+μ−jj + X at orders $$ \mathcal{O} $$ O (α7) and $$ \mathcal{O} $$ O (αsα6) and take all off-shell and interference contributions into account. Owing to the presence of enhanced Sudakov logarithms, the electroweak corrections amount to −16% of the leading-order electroweak fiducial cross section and induce significant shape distortions of differential distributions. The QCD corrections on the other hand are larger (+24%) than typical QCD corrections in VBS. This originates from considering the full computation including tri-boson contributions in a rather inclusive phase space. We also provide a leading-order analysis of all contributions to the cross section for pp → e+e−μ+μ−jj + X in a realistic setup.

scholarly journals Measurements of triple-differential cross sections for inclusive isolated-photon+jet events in $$\mathrm{p}\mathrm{p}$$ collisions at $$\sqrt{s} = 8\,\text {TeV} $$

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Phase Space ◽  
Transverse Momentum ◽  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Leading Order ◽  
Perturbative Quantum Chromodynamics ◽  
Triple Differential Cross Section ◽  
Perturbative Quantum

AbstractMeasurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in $$\mathrm{p}\mathrm{p}$$pp collisions at $$\sqrt{s} = 8$$s=8 TeV as a function of photon transverse momentum ($$p_{\mathrm {T}} ^{{\upgamma {}{}}}$$pTγ), photon pseudorapidity ($$\eta ^{{\upgamma {}{}}}$$ηγ), and jet pseudorapidity ($$\eta ^{\text {jet}}$$ηjet). The data correspond to an integrated luminosity of $$19.7{\,\text {fb}^{-1}} $$19.7fb-1 that probe a broad range of the available phase space, for $$|\eta ^{{\upgamma {}{}}} |<1.44$$|ηγ|<1.44 and $$1.57<|\eta ^{{\upgamma {}{}}} |<2.50$$1.57<|ηγ|<2.50, $$|\eta ^{\text {jet}} |<2.5$$|ηjet|<2.5, $$40< p_{\mathrm {T}} ^{{\upgamma {}{}}}<1000$$40<pTγ<1000$$\,\text {GeV}$$GeV, and jet transverse momentum, $$p_{\mathrm {T}} ^{\text {jet}}$$pTjet, > 25$$\,\text {GeV}$$GeV. The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.

scholarly journals Factorization of e+e− → H X cross section, differential in zh, PT and thrust, in the 2-jet limit

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
M. Boglione ◽  
A. Simonelli
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Belle Collaboration ◽  
Hadron Production ◽  
Leading Order ◽  
Transverse Momentum Dependent ◽  
Factorization Scheme ◽  
Phenomenological Studies ◽  
Cross Section Differential ◽  
Perturbative Part

Abstract Factorizing the cross section for single hadron production in e+e− annihilations is a highly non trivial task when the transverse momentum of the outgoing hadron with respect to the thrust axis is taken into account. We work in a scheme that allows to factorize the e+e−→ H X cross section as a convolution of a calculable hard coefficient and a Transverse Momentum Dependent (TMD) fragmentation function. The result, differential in zh, PT and thrust, will be given to all orders in perturbation theory and explicitly computed to Next to Leading Order (NLO) and Next to Leading Log (NLL) accuracy. The predictions obtained from our computation, applying the simplest and most natural ansatz to model the non-perturbative part of the TMD, are in exceptional agreement with the experimental measurements of the BELLE Collaboration. The factorization scheme we propose relates the TMD parton densities defined in 1-hadron and 2-hadron processes, restoring the possi- bility to perform global phenomenological studies of TMD physics including experimental data from semi-inclusive deep inelastic scattering, Drell-Yan processes, e+e−→ H1H2X and e+e−→ H X annihilations.

scholarly journals Charged current Drell-Yan production at N3LO

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Claude Duhr ◽  
Falko Dulat ◽  
Bernhard Mistlberger
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
Charge Asymmetry ◽  
Charged Current ◽  
Leading Order ◽  
Neutrino Pair ◽  
The Impact

Abstract We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to-leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual W± boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of W± bosons, as well as on the ratios of the production cross sections for W+, W− and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

scholarly journals The axion-baryon coupling in SU(3) heavy baryon chiral perturbation theory

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Thomas Vonk ◽  
Feng-Kun Guo ◽  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Heavy Baryon ◽  
Power Counting ◽  
Flavor Symmetry ◽  
Chiral Perturbation ◽  
Third Order ◽  
Stellar Objects ◽  
The Past ◽  
Dense Nuclear Matter

Abstract In the past, the axion-nucleon coupling has been calculated in the framework of SU(2) heavy baryon chiral perturbation theory up to third order in the chiral power counting. Here, we extend these earlier studies to the case of heavy baryon chiral perturbation theory with SU(3) flavor symmetry and derive the axion coupling to the full SU(3) baryon octet, showing that the axion also significantly couples to hyperons. As studies on dense nuclear matter suggest the possible existence of hyperons in stellar objects such as neutron stars, our results should have phenomenological implications related to the so-called axion window.

scholarly journals Forward dijets in proton-nucleus collisions at next-to-leading order: the real corrections

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Edmond Iancu ◽  
Yair Mulian
Keyword(s):  
Cross Section ◽  
Soft Gluon ◽  
Effective Theory ◽  
Dglap Evolution ◽  
Leading Order ◽  
Final State ◽  
Dijet Production ◽  
The Real ◽  
First Case ◽  
Subsequent Publication

Abstract Using the CGC effective theory together with the hybrid factorisation, we study forward dijet production in proton-nucleus collisions beyond leading order. In this paper, we compute the “real” next-to-leading order (NLO) corrections, i.e. the radiative corrections associated with a three-parton final state, out of which only two are being measured. To that aim, we start by revisiting our previous results for the three-parton cross-section presented in [1]. After some reshuffling of terms, we deduce new expressions for these results, which not only look considerably simpler, but are also physically more transparent. We also correct several errors in this process. The real NLO corrections to inclusive dijet production are then obtained by integrating out the kinematics of any of the three final partons. We explicitly work out the interesting limits where the unmeasured parton is either a soft gluon, or the product of a collinear splitting. We find the expected results in both limits: the B-JIMWLK evolution of the leading-order dijet cross-section in the first case (soft gluon) and, respectively, the DGLAP evolution of the initial and final states in the second case (collinear splitting). The “virtual” NLO corrections to dijet production will be presented in a subsequent publication.

scholarly journals Strong CP violation in spin-1/2 singly charmed baryons

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Y. Ünal ◽  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Dipole Moment ◽  
Form Factor ◽  
Cp Violation ◽  
Mass Shell ◽  
Chiral Expansion ◽  
Renormalization Scheme ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Charmed Baryons

Abstract We report on the calculation of the CP-violating form factor F3 and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD θ-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

Analysis of Twisting Stiffness for a Multifiber Composite Layer

1974 ◽  
Vol 41 (3) ◽  
pp. 658-662 ◽  
Author(s):  
C. W. Bert ◽  
S. Chang
Keyword(s):  
Cross Section ◽  
Least Squares Method ◽  
Rectangular Cross Section ◽  
Torsional Rigidity ◽  
Composite Layer ◽  
Circular Cross Section ◽  
Relaxation Method ◽  
Fiber Composites ◽  
Numerical Results ◽  
Torsion Problem

The twisting stiffness of a rectangular cross section consisting of a single row of solid circular cross-section fibers embedded in a matrix is analyzed. The problem is formulated as a Dirichlet torsion problem of a multielement region and solved by the boundary-point least-squares method. Numerical results for a single-fiber square cross section compare favorably with previous relaxation-method results. New numerical results for three and five-fiber composites suggest that the torsional rigidity of a multifiber composite can be approximated from the torsional rigidities of single and three-fiber models.

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