scholarly journals Pair production and bremsstrahlung of charged leptons

1974 ◽  
Vol 46 (4) ◽  
pp. 815-851 ◽  
Author(s):  
Yung-Su Tsai
2021 ◽  
Vol 81 (1) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  

AbstractA search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from $${\text {b}}$$ b quarks, and missing transverse momentum. The search uses data from proton-proton collisions at $$\sqrt{s}=13\,\text {TeV} $$ s = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 137$$\,{\text {fb}}^{-1}$$ fb - 1 . Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at $$95\%$$ 95 % confidence level on the masses of the top squark and the neutralino up to 925 and 450$$\,\text {GeV}$$ GeV , respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850$$\,\text {GeV}$$ GeV for neutralino masses below 420$$\,\text {GeV}$$ GeV . For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4$$\,\text {TeV}$$ TeV and 900$$\,\text {GeV}$$ GeV respectively for the top squark and the lightest neutralino.


2003 ◽  
Vol 18 (27) ◽  
pp. 5069-5098 ◽  
Author(s):  
MATTEO BECCARIA ◽  
MICHAEL MELLES ◽  
FERNAND M. RENARD ◽  
SALVATORE TRIMARCHI ◽  
CLAUDIO VERZEGNASSI

We consider the high energy behavior of the amplitudes for pair production of charged leptons, quarks, Higgs bosons, sleptons, squarks and charginos at lepton colliders. We give the general expressions of the leading quadratic and subleading linear logarithms that appear at the one-loop level, and derive the corresponding resummed expansions to subleading logarithmic order accuracy. Under the assumption of a relatively light SUSY scenario and choosing the MSSM as a specific model, we compare the predictions of the one-loop and of the resummed expansions at variable energy. We show that the two predictions are very close in the one TeV regime, but drastically differ in the few (2,3) TeV range.


1971 ◽  
Vol 105 (12) ◽  
pp. 780-781 ◽  
Author(s):  
Ya.B. Zel'dovich ◽  
Lev P. Pitaevskii ◽  
Valentin S. Popov ◽  
Aleksei A. Starobinskii

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