118868371
The Top Forward Backward Asymmetry with general Zcouplings
The measurement of the top forward-backward asymmetry in tproduction measured at the Tevatron shows deviation from the Standard Model prediction. A u → t transition via a flavor changing Zcan explain the data. We show that left handed tLuLZcouplings can be constrained from Bd,s mixing while the constrains on the right handed couplings tRuRZvanish in the limit of mu → 0. We then consider the most general form of the tuZinteraction which includes vector-axial vector as well as tensor type couplings and study how these couplings affect the top forward-backward asymmetry.
119451753
Extracting alpha from B0(d) --> K0 anti-K0 Decays
We propose a new method for obtaining the CP phase alpha, based on measurements of B0(d) --> K0 anti-K0, along with theoretical input. Due to the similarities of QCD factorization (QCDf) and perturbative QCD (pQCD), this input is basically the same for each of these models. Although the theoretical error is large at present, many of the contributing quantities will be better known in the future, leading to a smaller error. One outstanding question is the extent to which the precision on quark masses, especially m_c/m_b, can be improved. If one assumes that new physics is not present, the method can be used to predict the values of CP asymmetries in B0(d) --> K0 anti-K0: 0.02 <= A_{dir}^2 + A_{mix}^2 <= 0.125. A result outside this range would signal the existence of long-distance effects beyond those included in models of nonleptonic decays based on factorization (such as QCDf and pQCD), or the presence of new physics.
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.
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.
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.
12391468
IDENTIFYING THE CONTRIBUTIONS OF UNIVERSAL EXTRA DIMENSIONS IN THE HIGGS SECTOR AT LINEAR e+e- COLLIDERS
We study the dilepton–dijet signal in the dominant Higgs production channel at a linear e+e- collider. We estimate the effects of universal extra dimension (UED) by a simple analysis of the cross-sections. The heavy Kaluza–Klein excitations of the Standard Model fields in UED can significantly alter the decay properties of the Higgs boson to loop-driven final states. We show that by taking a simple ratio between cross-sections of two different final states this difference can be very easily highlighted.
6039154
Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider
We point out that interesting signals of the non-strongly interacting sector of the supersymmetric standard model arise from the production of charginos and neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC). In particular, if R-parity is violated, the hadronically quiet signals of charginos and neutralinos through direct production get considerably suppressed. We show that in such cases, the VBF channel can be useful in identifying this sector through clean and background-free final states.
2177649
Prospects of squark and slepton searches at a $\gamma \gamma$ collider
Abstract We examine the prospects of detecting sfermions at a gamma–gamma collider. Once produced, a slepton can decay into a pair of quarks (jets) through R -parity violating interactions. Similarly, a squark may decay into a lepton–quark pair. Analyzing the corresponding Standard Model backgrounds, namely 4-jet and dilepton plus dijet final states respectively, we show that the sfermion can be detected almost right upto the kinematic limit and its mass determined to a fair degree of accuracy. Similar statements also hold for nonsupersymmetric leptoquarks and diquarks.
17034941
Invisible charginos and neutralinos from gauge boson fusion: a way to explore anomaly mediation.
We point out that vector boson fusion at the Large Hadron Collider (LHC) can lead to useful signals for charginos and neutralinos in supersymmetric scenarios where these particles are almost invisible. The proposed signals are just two forward jets with missing transverse energy. It is shown that, in this way, one can put by far the strongest constraint on the parameter space of a theory with anomaly mediated supersymmetry breaking at the LHC. In addition, scenarios where the lightest neutralinos and charginos are Higgsino-like can give signals of the above type.
15133750
LHC signature of the minimal SUGRA model with a large soft scalar mass
Abstract Thanks to the focus point phenomenon, it is quite natural for the minimal SUGRA model to have a large soft scalar mass ( m 0 >1 TeV). A distinctive feature of this model is an inverted hierarchy, where the lighter stop has a significantly smaller mass than the other squarks and sleptons. Consequently, the gluino is predicted to decay dominantly via stop exchange into a channel containing 2 b and 2 W along with the LSP. We exploit this feature to construct a robust signature for this model at the LHC in leptonic channels with 3–4 b tags and a large missing- E T .