HEPData Search

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Double tag events in two photon collisions at LEP

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.

Phys.Lett.B 531 (2002) 39-51, 2002.

Inspire Record 565440 DOI 10.17182/hepdata.49820

Double-tag events in two-photon collisions are studied using the L3 detector at LEP centre-of-mass energies from root(s)=189 GeV to 209 GeV. The cross sections of the e+e- -> e+e- hadrons and gamma*gamma* -> hadrons processes are measured as a function of the photon virtualities, Q1^2 and Q2^2, of the two-photon mass, W_gammagamma, and of the variable Y=ln(W_gammagamma^2/(Q1 Q2)), for an average photon virtuality <Q2> = 16 GeV2. The results are in agreement with next-to-leading order calculations for the process gamma*gamma* -> q qbar in the interval 2 <= Y <= 5. An excess is observed in the interval 5 < Y <= 7, corresponding to W_gammagamma greater than 40 GeV . This may be interpreted as a sign of resolved photon QCD processes or the onset of BFKL phenomena.

6 data tables

Table 1

Differential cross section as a function of the photon virtualities Qi**2. Here Q1 is the virtuality w.r.t the electron vertex, and Q2 w.r.t the positron vertex. Data are given both before and after radiative corrections.

Table 2

Differential cross section as a function of W, the invariant mas of the virtual GAMMA*GAMMA* system. Data are given both before and after radiative corrections.

Table 3

Differential cross section as a function of the variable LN(W**2/Q1*Q2). Data are given both before and after radiative corrections.

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Leptoquarks and compositeness scales from a contact interaction analysis of deep inelastic e+- p scattering at HERA

The H1 collaboration Aid, S. ; Andreev, V. ; Andrieu, B. ; et al.

Phys.Lett.B 353 (1995) 578-588, 1995.

Inspire Record 394404 DOI 10.17182/hepdata.44997

A contact interaction analysis is presented to search for new phenomena beyond the Standard Model in deep inelastic $e~\pm p \rightarrow e~\pm \, hadrons$ scattering. The data are collected with the H1 detector at HERA and correspond to integrated luminosities of $0.909 \ {\rm pb}~{-1}$ and $2.947 \ {\rm pb}~{-1}$ for electron and positron beams, respectively. The differential cross sections $d\sigma / dQ~2$ are measured in the $Q~2$ range bet\-ween $160 \ \GeV~2$ and $20,000 \ \GeV~2$. The absence of any significant deviation from the Standard Model prediction is used to constrain the couplings and masses of new leptoquarks and to set limits on electron--quark compositeness scales and on the radius of light quarks.

2 data tables

Table 1

Additional overall normalization error of 3.5 pct due to systematic errors of the luminosity measurement.

Table 2

Additional overall normalization error of 1.8 pct due to systematic errors of the luminosity measurement.

Measurement of charged and neutral current e- p deep inelastic scattering cross-sections at high Q**2

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.

Phys.Rev.Lett. 75 (1995) 1006-1011, 1995.

Inspire Record 393918 DOI 10.17182/hepdata.45004

Deep inelastic $e~-p$ scattering has been studied in both the charged-current (CC) and neutral-current (NC) reactions at momentum transfers squared, $Q~2$, between 400 GeV$~2$ and the kinematic limit of 87500 GeV$~2$ using the ZEUS detector at the HERA $ep$ collider. The CC and NC total cross sections, the NC to CC cross section ratio, and the differential cross sections, $ d\sigma/dQ~2 $, are presented. For $Q~2 \simeq M_W~2$, where $M_W$ is the mass of the $W$ boson, the CC and NC cross sections have comparable magnitudes, demonstrating the equal strengths of the weak and electromagnetic interactions at high $Q~2$. The $Q~2$ dependence of the CC cross section determines the mass term in the CC propagator to be $M_{W} = 76 \pm 16 \pm 13$GeV.

4 data tables

Table 1

Data requested from authors.

Table 2

Neutral current cross sections.

Table 3

Charged current cross sections.

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