scholarly journals Tests of the Atomki anomaly in lepton pair decays of heavy mesons

2021 ◽  
Vol 103 (9) ◽  
Author(s):  
G. López Castro ◽  
Néstor Quintero
Keyword(s):  
Lepton Pair ◽  
Heavy Mesons

scholarly journals Lepton-pair production in dipion τ lepton decays

2021 ◽  
Vol 103 (1) ◽  
Author(s):  
J. L. Gutiérrez Santiago ◽  
G. López Castro ◽  
P. Roig
Keyword(s):  
Pair Production ◽  
Lepton Pair ◽  
Lepton Pair Production ◽  
Lepton Decays

scholarly journals Global analysis of the Sivers functions at NLO+NNLL in QCD

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Miguel G. Echevarria ◽  
Zhong-Bo Kang ◽  
John Terry
Keyword(s):  
Pair Production ◽  
Global Analysis ◽  
Vector Boson ◽  
Lepton Pair ◽  
Transverse Spin ◽  
Dglap Evolution ◽  
Spin Asymmetries ◽  
Lepton Pair Production ◽  
Asymmetry Data ◽  
The Impact

Abstract We perform global fit to the quark Sivers function within the transverse momentum dependent (TMD) factorization formalism in QCD. We simultaneously fit Sivers asymmetry data from Semi-Inclusive Deep Inelastic Scattering (SIDIS) at COMPASS, HERMES, and JLab, from Drell-Yan lepton pair production at COMPASS, and from W/Z boson at RHIC. This extraction is performed at next-to-leading order (NLO) and next-to-next-to leading logarithmic (NNLL) accuracy. We find excellent agreement between our extracted asymmetry and the experimental data for SIDIS and Drell-Yan lepton pair production, while tension arises when trying to describe the spin asymmetries of W/Z bosons at RHIC. We carefully assess the situation, and we study in details the impact of the RHIC data and their implications through different ways of performing the fit. In addition, we find that the quality of the description of W/Z vector boson asymmetry data could be strongly sensitive to the DGLAP evolution of Qiu-Sterman function, besides the usual TMD evolution. We present discussion on this and the implications for measurements of the transverse-spin asymmetries at the future Electron Ion Collider.

scholarly journals QED corrections in $$ \overline{B}\to \overline{K}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ at the double-differential level

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Gino Isidori ◽  
Saad Nabeebaccus ◽  
Roman Zwicky
Keyword(s):  
Phase Space ◽  
Detailed Analysis ◽  
Invariant Mass ◽  
Mass Distribution ◽  
Invariant Mass Distribution ◽  
Semileptonic Decays ◽  
Lepton Pair ◽  
Specific Choice ◽  
Slicing Method

Abstract We present a detailed analysis of QED corrections to $$ \overline{B}\to \overline{K}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ B ¯ → K ¯ ℓ + ℓ − decays at the double-differential level. Cancellations of soft and collinear divergences are demonstrated analytically using the phase space slicing method. Whereas soft divergences are found to cancel at the differential level, the cancellation of the hard-collinear logs ln mℓ require, besides photon-inclusiveness, a specific choice of kinematic variables. In particular, hard-collinear logs in the lepton-pair invariant mass distribution (q2), are sizeable and need to be treated with care when comparing with experiment. Virtual and real amplitudes are evaluated using an effective mesonic Lagrangian. Crucially, we show that going beyond this approximation does not introduce any further infrared sensitive terms. All analytic computations are performed for generic charges and are therefore adaptable to semileptonic decays such as $$ \overline{B}\to D\mathrm{\ell}\overline{\nu } $$ B ¯ → D ℓ ν ¯ .

scholarly journals Discovery of higher-order quantum electrodynamics effect for the vacuum pair production

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
W. Zha ◽  
Z. Tang
Keyword(s):  
Pair Production ◽  
Quantum Electrodynamics ◽  
World Wide ◽  
Order Effect ◽  
Higher Order ◽  
Lepton Pair ◽  
Scientific Problem ◽  
Sigma Level ◽  
Level Of Significance ◽  
Important Milestone

Abstract The higher-order quantum electrodynamics (QED) effect for vacuum pair production has been searched without success since 1954. In this paper, we show that the combined world-wide data of lepton pair vacuum production is about 20% smaller than the latest lowest order QED calculation with a 5.2 sigma-level of significance and is consistent with the corresponding higher-order QED result. We claim the discovery of higher-order effect for the QED pair production, which settles the dust of previous debates for several decades. The verification of higher-order QED effect is a fundamental scientific problem, which is an important milestone towards the nonperturbative and nonlinear regime of QED vacuum.

scholarly journals Heavy lepton pair production in nucleus–nucleus collisions at LHC energy – a case study

2012 ◽  
Vol 889 ◽  
pp. 1-7
Author(s):  
Jan-e Alam ◽  
Bedangadas Mohanty ◽  
Sarbani Majumder ◽  
Sanjay K. Ghosh ◽  
Rajarshi Ray
Keyword(s):  
Pair Production ◽  
Lepton Pair ◽  
Heavy Lepton ◽  
Lepton Pair Production

scholarly journals Low-mass lepton-pair production in p-Be collisions at 450 GeV/c

1995 ◽  
Vol 68 (1) ◽  
pp. 47-64 ◽  
Author(s):  
T. Åkesson ◽  
S. Almehed ◽  
A. L. S. Angelis ◽  
J. Antos ◽  
H. Atherton ◽  
...  
Keyword(s):  
Pair Production ◽  
Lepton Pair ◽  
Lepton Pair Production ◽  
Low Mass
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