14582667
Detecting matter effects in long baseline experiments
Experiments strongly suggest that the flavour mixing responsible for the atmospheric neutrino anomaly is very close to being maximal. Thus, it is of great theoretical as well as experimental importance to measure any possible deviation from maximality. In this context, we reexamine the effects of matter interactions in long baseline neutrino oscillation experiments. Contrary to popular belief, the muon neutrino survival probability is shown to be quite sensitive to matter effects. Moreover, for moderately long baselines, the difference between the survival probilities for νμ and μ is shown to be large and sensitive to the deviation of |U μ3| from maximality. Performing a realistic analysis, we demonstrate that a muon-storage ring ν-source alongwith an iron calorimeter detector can measure such deviations. (Contrary to recent claims, this is not so for the NuMI-MINOS experiment.) We also discuss the possible correlation in measuring U μ3 and U e3 in such experiment.
119099061
Probing the violation of equivalence principle at a muon storage ring via neutrino oscillation
Abstract We examine the possible tests of violation of the gravitational equivalence principle (VEP) at a muon storage ring via neutrino oscillation experiments. If the gravitational interactions of the neutrinos are not diagonal in the flavour basis and the gravitational interaction eigenstates have different couplings to the gravitational field, this leads to the neutrino oscillation. If one starts with μ + beam then appearance of τ ± , e + and μ − in the final state are the signals for neutrino oscillation. We have estimated the number of μ − events in this scenario in ν μ – N deep inelastic scattering. Final state lepton energy distribution can be used to distinguish the VEP scenario from the others. A large area of VEP parameter space can be explored at a future muon storage ring facility with moderate beam energy.
118278744
Higgs Boson Signals in Three b-jet Final States at the Fermilab Tevatron
At the Fermilab Tevatron, final states with three tagged b-jets could play an important role in searches for a Higgs boson with mass in the range 100-300 GeV. These signals arise from gb fusion and we demonstrate their observability in the limit of a large b-quark Yukawa coupling. Rather promising discovery limits on such a coupling are obtained and consequent effects on the parameter space of the Higgs-boson sector in the MSSM are discussed.
17475961
ZZH coupling: a probe to the origin of EWSB?
Abstract We argue that the ZZH coupling constitutes a simple probe of the nature of the scalar sector responsible for electroweak symmetry breaking. We demonstrate the efficacy of this measure through an analysis of four-dimensional models containing scalars in arbitrary representation of SU (2)× U (1), as well as extra-dimensional models with a non-factorizable geometry. A possible role for the t t H couplings is also discussed.
657627
Virtual graviton exchanges at the Z pole in large extra dimensions
Abstract In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza–Klein gravitons on the imaginary part of the amplitude of the process e + e − →f f are analyzed at the Z pole. Notably, the interference of the almost-continuous spectrum of the KK gravitons with the standard model resonant amplitude is finite and predictable in terms of the fundamental D-dimensional Planck scale MD. We find that, while the virtual-graviton effect on total cross sections vanishes at tree-level, both angular and polarization asymmetries are modified by terms whose relative effect is at most of order 10−4 for MD>1 TeV. Possible shifts in MZ, due to the changes in Breit–Wigner line shape are also discussed.
54016829
Deciphering universal extra dimension from the top quark signals at the CERN LHC
Models based on Universal Extra Dimensions predict Kaluza-Klein (KK) excitations of all Standard Model (SM) particles. We examine the pair production of KK excitations of top- and bottom-quarks at the Large Hadron Collider. Once produced, the KK top/bottom quarks can decay to b-quarks, leptons and the lightest KK-particle, γ1, resulting in 2 b-jets, two opposite sign leptons and missing transverse momentum, thereby mimicing top-pair production. We show that, with a proper choice of kinematic cuts, an integrated luminosity of 100 fb−1 would allow a discovery for an inverse radius upto R−1 = 750GeV.
118664901
Nonstandard interactions of tau neutrino via charged Higgs and $W'$ contribution
We consider charged Higgs and $W'$ gauge boson contributions to the quasielastic scattering $\nu_{\tau}+ n \rightarrow \tau^- + p$ and $\bar{\nu}_{\tau}+ p \rightarrow \tau^+ + n$ . These effects modify the standard model cross section for these processes and thus impact the extraction of the neutrino mixing angles $\theta_{23}$ and $\theta_{13}$ . We include form factor effects in our calculations and find the deviation of the actual mixing angle from the measured one, assuming the standard model cross section, can be significant and can depend on the energy of the neutrino.
17452333
Triple-Product Correlations in B -> V1 V2$ Decays and New Physics
In this paper we examine T-violating triple-product correlations (TP's) in B -> V1 V2 decays. TP's are excellent probes of physics beyond the standard model (SM) for two reasons: (i) within the SM, most TP's are expected to be tiny, and (ii) unlike direct CP asymmetries, TP's are not suppressed by the small strong phases which are expected in B decays. TP's are obtained via the angular analysis of B -> V1 V2. In a general analysis based on factorization, we demonstrate that the most promising decays for measuring TP's in the SM involve excited final-state vector mesons, and we provide estimates of such TP's. We find that there are only a handful of decays in which large TP's are possible, and the size of these TP's depends strongly on the size of nonfactorizable effects. We show that TP's which vanish in the SM can be very large in models with new physics. The measurement of a nonzero TP asymmetry in a decay where none is expected would specifically point to new physics involving large couplings to the right-handed b-quark.
199680997
The Charged Lepton Mass Matrix and Non-zero $\theta_{13}$ with TeV Scale New Physics
118310374
Probing New Physics in Higgs Couplings to Fermions using an Angular Analysis
The standard-model Higgs boson couples to quarks through a parity-even scalar Hqcou- pling. We show that the rare Higgs decay H ! V Z, where V is a vector quarkonium state such as J/ψ (c¯) or �(1S) (bb), can be used to search for the presence of a parity-odd pseudoscalar Hq¯ q coupling. Since both V and Z can decay to a pair of charged leptons, this presents an experimentally-clean channel that can be observed at the high-luminosity LHC or a future hadron collider. The P-even and P-odd Hqcouplings can be measured by analyzing the angular distribution of the final-state leptons.
119120552
Tau-neutrino as a probe of nonstandard interaction
Abstract We study the Δ-resonance and deep inelastic scattering contributions in the tau-neutrino–nucleon scattering ν τ + N → τ − + X and ν ¯ τ + N → τ + + X in the presence of a charged Higgs and a W ′ gauge boson. The new physics effects to the quasielastic process have been discussed in a previous work. The extractions of the atmospheric mixing angle θ 23 rely on the standard model cross sections for ν τ + N → τ − + X in ν τ appearance experiments. Corrections to the cross sections from the charged Higgs and W ′ contributions modify the measured mixing angle. We include form factor effects in the new physics calculations and find the deviations of the mixing angle. If high-energy Long Base Line experiments are designed to measure θ 13 through tau-neutrino appearance, the new physics effects to ν τ + N → τ − + X and ν ¯ τ + N → τ + + X can impact the extraction of this mixing angle. Finally, we investigate the new physics effects on the polarization of the τ ∓ leptons produced in ν τ ( ν ¯ τ ) –nucleon scattering.