119251173
Vanishing Dimensions and Planar Events at the LHC
We propose that the effective dimensionality of the space we live in depends on the length scale we are probing. As the length scale increases, new dimensions open up. At short scales the space is lower dimensional; at the intermediate scales the space is three-dimensional; and at large scales, the space is effectively higher dimensional. This setup allows for some fundamental problems in cosmology, gravity, and particle physics to be attacked from a new perspective. The proposed framework, among the other things, offers a new approach to the cosmological constant problem and results in striking collider phenomenology and may explain elongated jets observed in cosmic-ray data.
1066854
Rapidity correlations in W gamma production at hadron colliders.
We study the correlation of photon and charged lepton pseudorapidities, [eta]([gamma]) and [eta]([ital l]), [ital l]=[ital e],[mu], in [ital pp][sup ([minus])][r arrow][ital W][sup [plus minus]][gamma]+[ital X][r arrow][ital l][sup [plus minus]][ital ];sp[sub [ital T]][gamma]+[ital X]. In the standard model, the [Delta][eta]([gamma],[ital l])=[eta]([gamma])[minus][eta]([ital l]) differential cross section is found to exhibit a pronounced dip at [Delta][eta]([gamma],[ital l])[approx][minus plus]0.3 (=0) in [ital p[bar p]]([ital pp]) collisions, which originates from the radiation zero present in [ital q[bar q]][prime][r arrow][ital W][gamma]. The sensitivity of the [Delta][eta]([gamma],[ital l]) distribution to higher order QCD corrections, nonstandard [ital WW][gamma] couplings, the [ital W]+ jet fake'' background, and the cuts imposed is explored. At hadron supercolliders, next-to-leading order QCD corrections are found to considerably obscure the radiation zero. The advantages of the [Delta][eta]([gamma],[ital l]) distribution over other quantities which are sensitive to the radiation zero are discussed. We conclude that photon-lepton rapidity correlations at the Fermilab Tevatron offer a [ital unique] opportunity to search for the standard model radiation zero in hadronic [ital W][gamma] production.
118504997
Lower Dimensional Quantum Black Holes
There are theoretical reasons to think that space-time is lower dimensional at very short distances. If this is the case, quantum black holes produced at the LHC or in cosmic rays scattering live in lower dimensions. We discuss production cross section and signatures for the corresponding quantum black holes at the LHC within several different models of low-dimensional space-time.
16891404
Drell-Yan and diphoton production at hadron colliders and low scale gravity model
In the model of Arkani-Hamed, Dimopoulos, and Dvali where gravity is allowed to propagate in the extra dimensions of very large size, virtual graviton exchange between the standard model particles can give rise to signatures that can be tested in collider experiments. We study these effects in dilepton and diphoton production at hadron colliders. Specifically, we examine the double differential cross section in the invariant mass and scattering angle, which is found to be useful in separating the gravity effects from the standard model. In this work, sensitivity obtained using the double differential cross section is higher than that in previous studies based on single differential distributions. Assuming no excess of events over the standard model predictions, we obtain the following 95% confidence level lower limits on the effective Planck scale: 0.9\char21{}1.5 TeV in the Fermilab Tevatron run I, 1.3\char21{}2.5 TeV in run IIa, 1.7\char21{}3.5 TeV in run IIb, and 6.5\char21{}12.8 TeV at the CERN LHC. The range of numbers corresponds to the number of extra dimensions $n=7\ensuremath{-}2.$
18467342
Search for Exotics at the Tevatron: Present and Future
We present recent results on searches for non-SUSY new physics at the CDF and D0 Collaborations in the 1992-1996 Fermilab Tevatron run. While no compelling evidence for existence of new physics was found, the Tevatron data have excluded a significant region of the theoretically allowed phase space for a variety of non-SUSY extensions of the Standard Model. Tight limits on the existence of the following new phenomena are set: leptoquarks of all three generations, quark-lepton compositeness, 4-th generation quarks, fermiophobic Higgs, technicolor, etc. Prospects of the Tevatron experiments in Run II are discussed.
67851545
Higgs Bosons in the Standard Model and Beyond
In these proceedings I cover the latest results on the production and decay of the recently discovered Higgs boson. While the spin and properties of the new boson, such as its mass and couplings to bosons and fermions, are covered in a separate report, I focus on individual results in the main channels we use to study the properties of the new boson and to search for its possible cousins, with the focus on the latest results from the LHC and the Tevatron collaborations.
118051879
Radiative decays of hyperons