The Effective Potential And Additional Large Radius Compactified Space-Time Dimensions

The consequences of large radius extra space-time compactified dimensions on the four dimensional one loop effective potential are investigated for a model which includes scalar self interactions and Yukawa coupling to fermions. The Kaluza-Klein tower of states associated with the extra compact dimensions shifts the location of the effective potential minimum and modifies its curvature. The dependence of these effects on the radius of the extra dimension is illustrated for various choices of coupling constants and masses. For large radii, the consequence of twisting the fermion boundary condition on the compactified dimensions is numerically found to produce but a negligible effect on the effective potential.Comment: 14 pages, LaTeX, 6 Postscript figure

Spontaneous localization of bulk matter fields

We study models compactified on S^1/Z_2 with bulk and brane matter fields charged under U(1) gauge symmetry. We calculate the FI-terms and show by minimizing the resulting potential that supersymmetry or gauge symmetry is spontaneously broken if the sum of the charges does not vanish. Even if this sum vanishes, there could be an instability as a consequence of localized FI-terms. This leads to a spontaneous localization of charged bulk fields on respective branes.Comment: 11 pages, LaTeX, 1 figur

In-room test results at CNAO of an innovative PT treatments online monitor (Dose Profiler)

The use of C, He and O ions as projectiles in Particle Therapy (PT) treatments is getting more and more widespread as a consequence of their enhanced relative biological effectiveness and oxygen enhancement ratio, when compared to the protons one. The advantages related to the incoming radiation improved efficacy are requiring an accurate online monitor of the dose release spatial distribution. Such monitor is necessary to prevent unwanted damage to the tissues surrounding the tumour that can arise, for example, due to morphological changes occurred in the patient during the treatment with respect to the initial CT scan. PT treatments with ions can be monitored by detecting the secondary radiation produced by the primary beam interactions with the patient body along the path towards the target volume. Charged fragments produced in the nuclear process of projectile fragmentation can be emitted at large angles with respect to the incoming beam direction and can be detected with high efficiency in a nearly background-free environment. The Dose Profiler (DP) detector, developed within the INSIDE project, is a scintillating fibre tracker that allows an online reconstruction and backtracking of such secondary charged fragments. The construction and preliminary in-room tests performed on the DP, carried out using the 12C ions beam of the CNAO treatment centre using an anthropomorphic phantom as a target, will be reviewed in this contribution. The impact of the secondary fragments interactions with the patient body will be discussed in view of a clinical application. Furthermore, the results implications for a pre-clinical trial on CNAO patients, foreseen in 2019, will be discussed

Warped Phenomenology

We explore the phenomenology associated with the recently proposed localized gravity model of Randall and Sundrum where gravity propagates in a 5-dimensional non-factorizable geometry and generates the 4-dimensional weak-Planck scale hierarchy by an exponential function of the compactification radius, called a warp factor. The Kaluza-Klein tower of gravitons which emerge in this scenario have strikingly different properties than in the factorizable case with large extra dimensions. We derive the form of the graviton tower interactions with the Standard Model fields and examine their direct production in Drell-Yan and dijet events at the Tevatron and LHC as well as the KK spectrum line-shape at high-energy linear \epem colliders. In the case where the first KK excitation is observed, we outline the procedure to uniquely determine the parameters of this scenario. We also investigate the effect of KK tower exchanges in contact interaction searches. We find that present experiments can place meaningful constraints on the parameters of this model.Comment: 14 pages, LaTex, 3 fig

Cosmological Constraints on Theories with Large Extra Dimensions

In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the fundamental scale M_F, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially relevant to the case of two extra dimensions, since only if M_F is 10 TeV or less do deviations from the standard gravitational force law become evident at distances accessible to planned sub-mm gravity experiments. By examining the graviton decay contribution to the cosmic diffuse gamma radiation, we derive, for the case of two extra dimensions, a conservative bound M_F > 110 TeV, corresponding to r_2 < 5.1 times 10^-5 mm, well beyond the reach of these experiments. We also consider the constraint coming from graviton overclosure of the universe and derive an independent bound M_F > 6.5 h^(-1/2) TeV, or r_2 < .015 h mm.Comment: 10 pages, references adde

Collider Tests of Compact Space Dimensions Using Weak Gauge Bosons

We present collider tests of the recent proposal for weak-scale quantum gravity due to new large compact space dimensions in which only the graviton (\G) propagates. We show that the existing high precision LEP-I $Z$-pole data can impose non-trivial constraints on the scale of the new dimensions, via the decay mode Z\to f\bar{f}+\G ($f=q,\ell$). These bounds are comparable to those obtained at high energy colliders and provide the first sensitive probe of the scalar graviton. We also study W(Z)+\G production and the anomalous $WW(ZZ)$ signal from virtual \G-states at the Fermilab Tevatron, and compare them with the LEP-I bound and those from LEP-II and future linear colliders.Comment: 4 pages, 1 postscript figure include

Indirect Collider Signals for Extra Dimensions

A recent suggestion that quantum gravity may become strong near the weak scale has several testable consequences. In addition to probing for the new large (submillimeter) extra dimensions associated with these theories via gravitational experiments, one could search for the Kaluza Klein towers of massive gravitons which are predicted in these models and which can interact with the fields of the Standard Model. Here we examine the indirect effects of these massive gravitons being exchanged in fermion pair production in \epem annihilation and Drell-Yan production at hadron colliders. In the latter case, we examine a novel feature of this theory, which is the contribution of gluon gluon initiated processes to lepton pair production. We find that these processes provide strong bounds, up to several TeV, on the string scale which are essentially independent of the number of extra dimensions. In addition, we analyze the angular distributions for fermion pair production with spin-2 graviton exchanges and demonstrate that they provide a smoking gun signal for low-scale quantum gravity which cannot be mimicked by other new physics scenarios.Comment: Corrected typos, added table and reference

Fermion Mass Hierarchies and Small Mixing Angles from Extra Dimensions

In this paper we study renormalization-group evolutions of Yukawa matrices enhanced by Kaluza-Klein excited modes and analyze their infrared fixed-point structure. We derive necessary conditions to obtain hierarchies between generations on the fixed point. These conditions restrict how the fields in the models can extend to higher dimension. Several specific mechanisms to realize the conditions are presented. We also take account of generation mixing effects and find a scenario where the mixing angles become small at low energy even with large initial values at high-energy scale. A toy model is shown to lead realistic quark mass matrices.Comment: 23 pages, 7 figures, LaTeX, a supplementary explanation and references adde