118117079
Mutual consistency of the MINOS and MiniBooNE Antineutrino Results and Possible CPT Violation
Discussing the recent MINOS data on muon anti-neutrino disappearance and the MiniBooNE data on muon anti-neutrino to electron anti-neutrino oscillation, we show that the while the respective best fits are inconsistent with each other, significant overlap of allowed regions does exist. Assuming only three neutrino species, the data indicates a discrepancy of mass levels and mixing angles between the neutrino and the antineutrino sectors. We show that the existing data can be reconciled with a model of explicit CPT violation in the neutrino sector and estimate the magnitude of the required violation.
118555858
Enriching the exploration of the mUED model with event shape variables at the CERN LHC
Abstract We propose a new search strategy based on the event shape variables for new physics models where the separations among the masses of the particles in the spectrum are small. Collider signature of these models, characterized by low p T leptons/jets and low missing p T , are known to be difficult to look for. The conventional search strategies involving hard cuts may not work in such situations. As a case study, we have investigated the hitherto neglected jets + missing E T signature – known to be a challenging one – arising from the pair productions and decay of n = 1 KK-excitations of gluons and quarks in the minimal Universal Extra Dimension (mUED) model. Judicious use of the event shape variables enables us to reduce the Standard Model backgrounds to a negligible level. We have shown that in mUED, R − 1 up to 850 GeV can be explored or ruled out with 12 fb −1 of integrated luminosity at the 7 TeV run of the LHC. We also discuss the prospects of employing these variables for searching other beyond Standard Model physics with compressed or partially compressed spectra.
12332850
New Higgs signals from vector boson fusion in R-parity violating supersymmetry
We investigate signals of the lightest neutral Higgs in an R-parity violating supersymmetric model through the vector boson fusion mechanism. Assuming that R-parity is violated through lepton number, and locating regions in the parameter space where decays of such a neutral scalar into a pair of lightest neutralinos can be significant, we proceed to calculate the event rates for final states arising from decays of the neutralinos through both $\lambda$-and $\lambda'$-type interactions. Regions of the parameter space where each of these types of interactions can lead to detectable events are identified. The possibilities where such signals can be faked by other superparticles (squarks, gluinos, charginos and neutralinos) are also investigated. It is found that over a sizable region, one can obtain distinguishable signals of an intermediate mass neutral scalar from a study of the suggested final states at the Large Hadron Collider.
16309440
Slepton production from gauge boson fusion
We emphasize that charged slepton pairs produced via vector-boson fusion along with two high-mass, high-pT forward and backward jets (in two opposite hemispheres) can have a higher production cross section for heavy slepton masses than that from conventional Drell-Yan production at a hadronic collider such as the CERN LHC. We analyze the signal and leading backgrounds in detail in the minimal supersymmetric standard model with conserved baryon and lepton numbers. Our investigation reveals that the mass reach of the vector-boson fusion channel is certainly an improvement over the scope of the Drell-Yan mode.
11138073
Large extra dimension effects in Higgs boson production at linear colliders and Higgs factories
In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza-Klein graviton and graviscalar interference with Higgs boson production amplitudes are computed at linear colliders and Higgs factories. 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 Plank scale MD and the number of extra dimensions δ. We find that, for MD 1 TeV and δ = 2, effects of the order of a few percent could be detected for heavy Higgs bosons (mH>500 GeV) in Higgs production both via WW fusion in e+e− colliders and at μ+μ− Higgs-boson factories.
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.
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.
17027727
Getting SM and New Physics CP phases from $B$ Decays
A method to extract Standard Model(SM) CP phases involving B decays is presented. The method involves a pair of decays where one decay receives a significant $b \to d$ penguin contribution while the second has a significant $b \to s$ penguin contribution, but is dominated by a single amplitude. SM CP phase information is obtained using the fact that the $b \to s$ transition amplitude is related by SU(3) to a piece of the amplitude with the $b \to d$ transition. If there is significant new physics only in $b \to s$ transitions and not in $b \to d$ transitions then this method can be used to measure new physics(NP) phases.
118592122
Probing light pseudoscalar, axial vector states through $\eta_{b} \to\tau^{+}\tau^{-}$
In this paper, we explore the decay ${\ensuremath{\eta}}_{b}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ as a probe for a light pseudoscalar or a light axial vector state. We estimate the standard model branching ratio for this decay to be $\ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$. We show that considerably larger branching ratios, up to the present experimental limit of $\ensuremath{\sim}8%$, are possible in models with a light pseudoscalar or a light axial vector state. As we do not include possible mixing effects between the light pseudoscalar and the ${\ensuremath{\eta}}_{b}$, our results should be reliable when the pseudoscalar mass is away from the ${\ensuremath{\eta}}_{b}$ mass.
17090268
S-wave phase shift in Lambda-pi scattering
We calculate the s-wave strong interaction $\Lambda$$\pi$ phase shift at the $\Xi$ mass taking into account contributions from the ${{\frac{1}{2}}}^{-}$ and ${{\frac{3}{2}}}^{-}$ $\Sigma$ resonances. We find the S-wave phase shift to be small, of the order of 0.3 degrees and bounded by 0.5 degrees.
118636509
Predictions for $B \to \tau \bar{\mu} + \mu \bar{\tau} $
The observation of $B \to \tau \bar{\mu} + \mu \bar{\tau} $ at present experiments would be a clear sign of new physics. In this paper we calculate this process in a 2HDM framework where the decay is mediated by the exchange of spin zero particle with flavour changing neutral current couplings. If we identify the scalar with the the newly discovered state at LHC with a mass $% \sim 125 $ GeV then we get $BR(B_s \to \tau \bar{\mu} + \mu \bar{\tau}) \sim 10^{-6}$ and $BR(B_d \to \tau \bar{\mu} + \mu \bar{\tau}) \sim 10^{-7}$. We also calculate this process in minimal supersymmetric standard model and find $BR(B_s \to \tau \bar{\mu} + \mu \bar{\tau}) \sim 10^{-11}$.