Decay-Time Asymmetries at the B-Factories

Absract (Invited talk at the X DAE High Energy Physics symposium in December 1992, held at Tata Institute of Fundamental Research, Bombay)Comment: 20pages, TIFR/TH/93-1

On P-wave meson decay constants in the heavy quark limit of QCD

In previous work it has been shown that, either from a sum rule for the subleading Isgur-Wise function $\xi_3(1)$ or from a combination of Uraltsev and Bjorken SR, one infers for $P$-wave states $|\tau_{1/2}(1)| \ll |\tau_{3/2}(1)|$. This implies, in the heavy quark limit of QCD, a hierarchy for the {\it production} rates of $P$-states $\Gamma(\bar{B}_d \to D ({1 \over 2}) \ell \nu) \ll \Gamma(\bar{B}_d \to D ({3 \over 2}) \ell \nu)$ that seems at present to be contradicted by experiment. It was also shown that the decay constants of $j = {3 \over 2}$ $P$-states vanish in the heavy quark limit of QCD, $f_{3/2}^{(n)} = 0$. Assuming the {\it model} of factorization in the decays $\bar{B}_d \to \bar{D}_s^{**}D$, one expects the opposite hierarchy for the {\it emission} rates $\Gamma(\bar{B}_d \to \bar{D}_s ({3 \over 2}) D) \ll \Gamma(\bar{B}_d \to \bar{D}_s ({1 \over 2}) D)$, since $j = {1 \over 2}$ $P$-states are coupled to vacuum. Moreover, using Bjorken SR and previously discovered SR involving heavy-light meson decay constants and IW functions, one can prove that the sums $\sum\limits_n ({f^{(n)} \over f^{(0)}})^2$, $\sum\limits_n ({f_{1/2}^{(n)} \over f^{(0)}})^2$ (where $f^{(n)}$ and $f_{1/2}^{(n)}$ are the decay constants of $S$-states and $j = {1\over 2}$ $P$-states) are divergent. This situation seems to be realized in the relativistic quark models \`a la Bakamjian and Thomas, that satisfy HQET and predict decays constants $f^{(n)}$ and $f_{1/2}^{(n)}$ that do not decrease with the radial quantum number $n$.Comment: 7 pages, Late

Grand Unification of Quark and Lepton FCNCs

In the context of Supersymmetric Grand Unified theories with soft breaking terms arising at the Planck scale, it is generally possible to link flavor changing neutral current and CP violating processes occurring in the leptonic and hadronic sectors. We study the correlation between flavor changing squark and slepton mass insertions in models \`a la SU(5). We show that the constraints coming from lepton flavor violation exhibit a strong impact on CP-violating B decays.Comment: 4 pages, 1 figur

New Heavy Quark Limit Sum Rules involving Isgur-Wise Functions and Decay Constants

We consider the dominant $c\bar{c}$ contribution to $\Delta \Gamma$ for the $B_s^0$-$\bar{B}_s^0$ system in the heavy quark limit for both $b$ and $c$ quarks. In analogy with the Bjorken-Isgur-Wise sum rule in semileptonic heavy hadron decay, we impose duality between the parton model calculation of $\Delta \Gamma$ and its estimation by a sum over heavy mesons. Varying the mass ratio $m_c/m_b$ and assuming factorization and saturation by narrow resonances $(N_c \to \infty$), we obtain new sum rules that involve the Isgur-Wise functions $\xi^{(n)}(w)$ and $\tau^{(n)}_{1/2}(w)$ and the decay constants $f^{(n)}$, $f^{(n)}_{1/2}$ ($n$ stands for any radial excitation). Alternatively, we deduce the sum rules with another method free of the factorization hypothesis, from the saturation of the expectation value of a product of two currents by heavy hadrons and by the corresponding free quarks. The sum rules read $\sum\limits_{n}{f^{(n)} \over f^{(0)}} \xi^{(n)}(w) = 2 \sum\limits_{n}{f^{(n)}_{1/2} \over f^{(0)}} \tau^{(n)}_{1/2}(w) = 1$, valid for all $w$. Moreover, we obtain, in the heavy quark limit, $f^{(n)}_{3/2} = 0$. As a consequence, unlike the BIW sum rule, the slope of the elastic function $\xi (w)$ is related to radial excitations alone. These are generalizations, rigorous for QCD in the heavy quark limit, of results that have an easy understanding in the non-relativistic quark model.Comment: 15 page

Searching for new physics in b→ssdˉb\to s s \bar d decays

For any new physics possibly emerging in the future B experiments, the problem is how to extract the signals from the SM background. We consider the decay $b\to s s\bar d$ which is very small in the SM. In the MSSM this decay is possibly accessible in the future experiments. In the supersymmetric models with R-parity violating couplings, this channel is not strictly constrained, thus being useful in obtaining bounds on the lepton-number violating couplings. A typical candidate for the suggested search is the $B^-\to K^-K^-\pi^+$ mode.Comment: 9 pages, one figure, late

Constraining New Physics with the CDF Measurement of CP Violation in B→ψKSB \to \psi K_S

Recently, the CDF collaboration has reported a measurement of the CP asymmetry in the $B\to\psi K_S$ decay: $a_{\psi K_S}=0.79^{+0.41}_{-0.44}$. We analyze the constraints that follow from this measurement on the size and the phase of contributions from new physics to B-\barB mixing. Defining the relative phase between the full $M_{12}$ amplitude and the Standard Model contribution to be $2\theta_d$, we find a new bound: \sin2\theta_d\gsim-0.6 (-0.87) at one sigma (95% CL). Further implications for the CP asymmetry in semileptonic B decays are discussed.Comment: 13 pages, harvmac, 3 figures; v2: a discussion of new physics effects on tree level decays added; references added; accepted for publication in Physical Review Letter

Long distance contribution to K+→π+ννˉK^+ \to \pi^+ \nu {\bar \nu} decay and O(p4)O(p^4) terms in CHPT

The long distance contribution to $K^+ \to \pi^+ \nu {\bar \nu}$ is calculated using chiral perturbation theory. The leading contribution comes from $O(p^4)$ tree terms. The branching ratio of the $O(p^4)$ long distance contribution is found to be of order $10_{-3}$ smaller than the short distance contributions.Comment: 12 pages, 1 figure (available upon request

CP violation and CKM phases from angular distributions for BsB_s decays into admixtures of CP eigenstates

We investigate the time-evolutions of angular distributions for $B_s$ decays into final states that are admixtures of CP-even and CP-odd configurations. A sizable lifetime difference between the $B_s$ mass eigenstates allows a probe of CP violation in time-dependent untagged angular distributions. Interference effects between different final state configurations of $B_s\to D^{*+}_s D^{*-}_s$, $J/\psi \phi$ determine the Wolfenstein parameter $\eta$ from untagged data samples, or -- if one uses $|V_{ub}|/|V_{cb}|$ as an additional input -- the notoriously difficult to measure CKM angle $\gamma$. Another determination of $\gamma$ is possible by using isospin symmetry of strong interactions to relate untagged data samples of $B_s\to K^{\ast+} K^{\ast-}$ and $B_s\to K^{\ast0} \overline{K^{\ast0}}$. We note that the untagged angular distribution for $B_s\to\rho^0 \phi$ provides interesting information about electroweak penguins.Comment: 19 pages, LaTeX, no figure

Sneutrino-induced like sign dilepton signal with conserved R-parity

Lepton number violation could be manifest in the sneutrino sector of supersymmetric extensions of the standard model with conserved R-parity. Then sneutrinos decay partly into the ``wrong sign charged lepton'' final state, if kinematically accessible. In sneutrino pair production or associated single sneutrino production, the signal then is a like sign dilepton final state. Under favourable circumstances, such a signal could be visible at the LHC or a next generation linear collider for a relative sneutrino mass-splitting of order ${\cal O}(0.001)$ and sneutrino width of order ${\cal O}$(1 GeV). On the other hand, the like sign dilepton event rate at the TEVATRON is probably too small to be observable.Comment: 19 pages, 14 Figures. Section about LSD at LHC and TEVATRON added. Previous Title "Single sneutrino production and the wrong charged lepton signal

Measuring ∣Vub∣|V_{ub}| with B→Ds+Xu\to D_s^+ X_u transitions

We propose the determination of the CKM matrix element $|V_{ub}|$ by the measurement of the spectrum of $B \to D_s^+ X_u$, dominated by the spectator quark model mechanism $\bar{b} \to D_s^{(*)+} \bar{u}$. The interest of considering $B \to D_s^+X_u$ versus the semileptonic decay is that more than 50 % of the spectrum for $B \to D_s^+ X_u$ occurs above the kinematical limit for $B \to D_s^+ X_c$, while most of the spectrum $B \to l \nu X_u$ occurs below the $B \to l \nu X_c$ one. Furthermore, the measure of the hadronic mass $M_X$ is easier in the presence of an identified $D_s$ than when a $\nu$ has been produced. As a consistency check, we point out that the rate $\bar{b} \to D_s^{(*)+} \bar{c}$ (including QCD corrections that we present elsewhere) is consistent with the measured $BR (B \to D_s^{\pm} X)$. Although the hadronic complications may be more severe in the mode that we propose than in the semileptonic inclusive decay, the end of the spectrum in $B \to l \nu X_u$ is not well understood on theoretical grounds. We argue that, in our case, the excited $D_s^{**}$, decaying into $D K$, do not contribute and, if there is tagging of the $B$ meson, the other mechanisms to produce a $D_s$ of the right sign are presumably small, of $O(10^{-2})$ relative to the spectator amplitude, or can be controlled by kinematical cuts. In the absence of tagging, other hadronic backgrounds deserve careful study. We present a feasability study with the BaBar detector.Comment: 22 pages, LaTe