13923475
Measuring new physics parameters in B penguin decays
Abstract We examine new-physics (NP) effects in B decays with large b ¯ → s ¯ penguin amplitudes. Decays involving b ¯ → d ¯ penguins are assumed to be unaffected. We consider a model-independent parametrization of such NP. We argue that NP strong phases are negligible relative to those of the standard model. This allows us to describe the NP effects in terms of a small number of effective amplitudes A NP q ( q = u , d , s , c ) and corresponding weak phases Φ q . We then consider pairs of neutral B decays which are related by flavour SU(3) in the standard model. One receives a large b ¯ → s ¯ penguin component and has a NP contribution; the other has a b ¯ → d ¯ penguin amplitude and is unaffected by NP. The time-dependent measurement of these two decays allows the measurement of the NP parameters A NP q and  Φ q . The knowledge of these parameters allows us to rule out many NP models and thus partially identify the new physics.
118720377
Explaining the $B \to K^\ast \mu^+ \mu^-$ data with scalar interactions
Recent LHCb results on the decay $B \to K^\ast \mu^+ \mu^-$ show significant deviations from the SM estimates in some of the angular correlations. In this paper we study the possibility of explaining these deviations using new scalar interactions. We show that new dimension-6 four-quark operators of scalar and pseudo-scalar type can successfully account for the discrepancies even after being consistent with other experimental measurements. We also briefly discuss possible extensions of the Standard Model where these operators can be generated.
15656176
Understanding the nature of Ds(2317) and Ds(2460) through nonleptonic B decays
We consider the nonleptonic B decays B→D(∗)Ds(2317) and B→D(∗)Ds(2460), involving the newly discovered Ds(2317) and the Ds(2460) states. We find that experiments indicate disagreement with model calculations of their properties and/or breakdown of the factorization assumption for these decays. We point out that decays involving Bs mesons where the Ds resonances can be produced via the weak decay of the b quark can provide further information about the nature of these newly discovered states. We also propose a model to calculate the two body nonleptonic decays B→D(∗)Ds(2317)(Ds(2460)), if the Ds(2317) and Ds(2460) are interpreted as DK and D∗K molecules.
119063690
$B \to VV$ Decays - Polarization and Triple Products
We discuss how triple product asymmetries can be used to discover and constrain new physics in $B \to VV$ decays.
118496504
Model independent predictions for rare top decays with weak coupling
Measurements at B factories have provided important constraints on new physics in several rare processes involving the B meson. New physics, if present in the b quark sector may also affect the top sector. In an effective Lagrangian approach, we write down operators, where effects in the bottom and the top sector are related. Assuming the couplings of the operators to be of the same size as the weak coupling g of the standard model and taking into account constraints on new physics from the bottom sector as well as top branching ratios, we make predictions for the rare top decays t{yields}cV, where V={gamma}, Z. We find branching fractions for these decays within possible reach of the LHC. Predictions are also made for t{yields}sW.
199680997
The Charged Lepton Mass Matrix and Non-zero $\theta_{13}$ with TeV Scale New Physics
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.
118588278
Boundary Localized Terms in Universal Extra-Dimensional Models through a Dark Matter perspective
In universal extra dimension (UED) models with one compactified extra dimension, a Z2 symmetry, termed KK-parity, ensures the stability of the lightest Kaluza-Klein particle (LKP) which could be a viable dark matter candidate. This symmetry leads to two fixed points. In non-minimal versions of UED boundary-localized (kinetic or mass) terms (BLT) for different fields are included at these fixed points and KK-parity may be violated. However, BLTs with same strength at both points induce a new Z2 symmetry which restores the stability of the LKP. We show that the BLTs serve to relax the bounds set on the compactification scale in UED by the observed dark matter relic density. At the same time, the precision of the dark matter measurements severely correlates the BLT parameters of gauge bosons and fermions. Depending on the parameter values, the LKP can be chosen to be the level-1 photon, which is essentially the B (1) , or the level-1 Z-boson, basically the W (1) 3 . We find that in the latter case the relic density is too small if the W
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.
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.
15877
Invisible Higgs in theories of large extra dimensions
We discuss the possibility of detecting a Higgs boson in future collider experiments if large extra dimensions are realized in nature. In such a case, the Higgs boson can decay invisibly by oscillating into a graviscalar Kaluza-Klein (KK) tower. We show that the search for such a Higgs at an ee linear collider entails more complications than are usually thought of in relation to an invisibly decaying Higgs, the main sources of such complications being the simultaneous presence of a continuum graviton production and the broadening of the Higgs peak. We discuss possible ways of overcoming such difficulties, and conclude that the detection of such a Higgs boson might still be a problem beyond the mass range of 250-300 GeV.