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.
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.
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.
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.
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.
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.
18756859
Hunting radions at linear colliders
Abstract We investigate the possibility to disentangle the radions in the Randall–Sundrum scenario from Higgs boson at the next generation high energy e + e − linear colliders. Due to trace anomaly, the radion coupling (and in turn the branching ratio) to gluons is enhanced over the same for the Standard Model (SM) higgs. We study the radion φ production at electron–positron colliders, via the process e + e − →ν ν φ , and propose to investigate radion decay to a pair of gluons. At 500 GeV center of mass energy, our signal is not very promising. We find our results are encouraging for finding radion and differentiating it from higgs for center of mass energies of 1 TeV and above.
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.
1534033
Probing two universal extra dimensions at international linear collider
Abstract We discuss collider signatures of ( 1 , 1 ) th Kaluza–Klein (KK) mode vector bosons in the framework of two universal extra dimension model, at a future e + e − collider. Production of B μ ( 1 , 1 ) and W 3 μ ( 1 , 1 ) , the ( 1 , 1 ) th KK mode vector bosons, are considered in association with a hard photon. Without caring about the decay products of B μ ( 1 , 1 ) or W 3 μ ( 1 , 1 ) , one can measure the masses of these particles just by looking at the photon energy distribution. Once produced B μ ( 1 , 1 ) ( W 3 μ ( 1 , 1 ) ) dominantly decays to a pair of jets or to a pair of top quarks. Thus we look for a pair of jets or a pair of top quarks in association with a photon. Upto the kinematic limit (with e + e − center-of-mass energies of 0.5 TeV and 1 TeV) of the collider, signals from the B μ ( 1 , 1 ) production and decay in both the above mentioned channels are greater than the 5σ fluctuation of the Standard Model background with 500 f b −1 integrated luminosity. However, the number of events from W 3 μ ( 1 , 1 ) production and decay is smaller and its detection prospect is not very good.
119178079
Universal Extra-Dimensional Models with Boundary Localized Kinetic Terms: Probing at the LHC
In universal extra-dimensional models a conserved $Z_2$ parity ensures the stability of the lightest Kaluza-Klein particle, a potential dark-matter candidate. We show here that boundary-localized kinetic terms, in general, do not preserve this symmetry. We examine the single production of a Kaluza-Klein excitation of the photon and its decay to zero-mode fermion-antifermion pairs in the presence of such terms. We explore how experiments at the Large Hadron Collider at CERN can help constrain the boundary-localized kinetic terms for different choices of the compactification radius.