| 1. |
|
|
| 2. |
- Alwall, Johan, et al.
(författare)
-
Improved description of charged Higgs boson production at hadron colliders
- 2004
-
Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; 0412:050
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new method for matching the two twin-processes gb→H±t and gg→H±tb in Monte Carlo event generators. The matching is done by defining a double-counting term, which is used to generate events that are subtracted from the sum of these two twin-processes. In this way we get a smooth transition between the collinear region of phase space, which is best described by gb→H±t, and the hard region, which requires the use of the gg→H±tb process. The resulting differential distributions show large differences compared to both the gb→H±t and gg→H±tb processes illustrating the necessity to use matching when tagging the accompanying b-jet.
|
|
| 3. |
|
|
| 4. |
- Alwall, Johan, et al.
(författare)
-
The pp -> tbH+/- process at the Tevatron in Herwig and Pythia simulations
- 2004
-
Ingår i: The European Physical Journal C: Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 39, s1, s. s37-s39
-
Tidskriftsartikel (refereegranskat)abstract
- Charged Higgs boson production in association with a top quark could be the first indication of the existence of Higgs particles. The Tevatron Run-II started data-taking in April 2001 at $\sqrt s=1960$ GeV and could probe the existence of a charged Higgs boson beyond the current mass limit. We study the $\rm p\bar p \rightarrow tbH^\pm$ production process with Monte Carlo simulations in HERWIG and PYTHIA, comparing expected cross sections and basic selection variables.
|
|
| 5. |
|
|
| 6. |
- Alwall, Johan, et al.
(författare)
-
Interpretation of electron-proton scattering at low Q2
- 2004
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 596, s. 77-83
-
Tidskriftsartikel (refereegranskat)abstract
- Low-Q2 photons do not resolve partons in the proton, which gives problems when applying the deep inelastic scattering formalism, such as an unphysical, negative gluon density extracted from data. Considering instead hadronic fluctuations of the photon, we show that the generalised vector meson dominance model (GVDM) gives a good description of the measured cross section at low Q2, i.e., reproduces F2(x,Q2), using only few parameters with essentially known values. Combining GVDM and parton density functions makes it possible to obtain a good description of F2 data over the whole range of x and Q2.
|
|
| 7. |
|
|
| 8. |
- Alwall, Johan, et al.
(författare)
-
Strange quark asymmetry in the nucleon and the NuTeV anomaly
- 2004
-
Ingår i: Physical Review D. - 0556-2821. ; 70, s. 111505(R)-
-
Tidskriftsartikel (refereegranskat)abstract
- The NuTeV anomaly of a nonuniversal value of the fundamental parameter sin2thetaW in the electroweak theory has been interpreted as an indication for new physics beyond the standard model. However, the observed quantity depends on a possible asymmetry in the momentum distributions of strange quarks and antiquarks in the nucleon. This asymmetry occurs naturally in a phenomenologically successful physical model for such parton distributions, which reduces the NuTeV result to only about 2 standard deviations from the standard model.
|
|
