Exclusive rare B -> K*e+e- decays at low recoil: controlling the long-distance effects

We present a model-independent description of the exclusive rare decays B-> K* e+e- in the low recoil region (large lepton invariant mass q^2 ~ m_b^2). In this region the long-distance effects from quark loops can be computed with the help of an operator product expansion in 1/Q, with Q={m_b, \sqrt{q^2}}. Nonperturbative effects up to and including terms suppressed by Lambda/Q and mc^2/mb^2 relative to the short-distance amplitude can be included in a model-independent way. Based on these results, we propose an improved method for determining the CKM matrix element |V{ub}| from a combination of rare and semileptonic B and D decays near the zero recoil point. The residual theoretical uncertainty from long distance effects in this |V{ub}| determination comes from terms in the OPE of order alpha_s(Q)\Lambda/mb, alpha_s^2(Q), mc^4/mb^4$ and duality violations and is estimated to be below 10%.Comment: 21 pages RevTex, 2 figures; v3: extensive numerical changes in the NLL analysis, with improved stability under scale dependence. Typos fixed, version to appear in Phys.Rev.

Flavor changing effects on single charged Higgs boson production associated with a bottom-charm pair at CERN Large Hadron Collider

We study flavor changing effects on the \ppbchT process at the Large Hadron Collider(LHC), which are inspired by the left-handed up-type squark mixings in the Minimal Supersymmetric Standard Model(MSSM). We find that the SUSY QCD radiative corrections to $bcH^\pm$ coupling can significantly enhance the cross sections at the tree-level by a factor about $1.5 \sim 5$ with our choice of parameters. We conclude that the squark mixing mechanism in the MSSM makes the \ppbchT process a new channel for discovering a charged Higgs boson and investigating flavor changing effects.Comment: One Latex file, 27 pages, 8 figures,to be appeared in PR

Bˉ→Xsγ\bar{B}\to X_s \gamma in the Two Higgs Doublet Model up to Next-to-Next-to-Leading Order in QCD

We compute three-loop matching corrections to the Wilson coefficients $C_7$ and $C_8$ in the Two Higgs Doublet Model by applying expansions for small, intermediate and large charged Higgs boson masses. The results are used to evaluate the branching ratio of $\bar{B}\to X_s \gamma$ to next-to-next-to leading order accuracy, and to determine an updated lower limit on the charged Higgs boson mass. We find \mhplus \ge 380 GeV at 95% confidence level when the recently completed BABAR data analysis is taken into account. Our results for the charged Higgs contribution to the branching ratio exhibit considerably weaker sensitivity to the matching scale $\mu_0$, as compared to previous calculations.Comment: 20 pages, 15 figures; v2: minor modifications, matches published version in JHE

Comment on nonperturbative effects in B→XsγB\to X_s\gamma

Uncertainties in the theoretical prediction for the inclusive $B\to X_s\gamma$ decay rate are discussed. We emphasize that there is no operator product expansion for this process. Nonetheless, some nonperturbative effects involving a virtual $c\bar c$ loop are calculable using the operator product expansion. They give a contribution to the decay rate that involves the B meson matrix element of an infinite tower of operators. The higher dimension operators give effects that are only suppressed by powers of $m_b\Lambda_{QCD}/m_c^2 \sim 0.6$, but come with small coefficients.Comment: 9 pages revtex, 2 figures included; minor changes, to appear in Phys. Lett.

Epigenetic mechanisms, trauma, and psychopathology: Targeting chromatin remodeling complexes

Environmental pressure affects the genotype throughout different epigenetic processes. There is currently ample evidence on the role of epigenetics in developing various mental disorders. A burden of environmental pressure, such as psychological trauma, and its influence on genotype can lead to a variety of psychopathologies. Thus, this study focuses on the epigenetic activity of the complex protein machinery operating on chromatin-the ATP-dependent chromatin remodeling complexes. Although there are several recent studies on the molecular structure, functions, and taxonomy of ATP-dependent chromatin remodeling complexes, the focus of this paper is to highlight the importance of those 'protein machines' in developing psychiatric disorders. Data were obtained from human preclinical and clinical studies. The results of this review indicate an importance of ATP-dependent chromatin remodeling complexes in the interaction between environmental factors, including traumatic events, and genetic vulnerability to stress. Several studies indicate that ATP-dependent chromatin remodeling complexes play a crucial role in the development and consolidation of memory, in neurodevelopmental processes, and in etiology depressive-like behavior. Thus, the activity of those 'protein machines' emerges as a key factor in the pathophysiology of various psychiatric diseases. It can also be concluded that the limitations of clinical studies may be explained by inappropriate laboratory methods and research paradigms due to the delayed timeframe of biochemical responses to environmental stimuli. Future research in this field may enable a better understanding of the pathophysiology of psychiatric diseases and contribute to the development of novel molecular treatment targets. - 2019 Walter de Gruyter GmbH, Berlin/Boston 2019

Exact αs\alpha _s Calculation of b→s+γb\rightarrow s + \gamma , \ b→s+gb\rightarrow s + g

We present an exact $\alpha_s$ calculation of the Wilson coefficients associated with the dipole moment operators. We also give an estimate of the branching ratio for $b\rightarrow s \gamma$. We find that higher dimensional effects are under control within $9\%$ for $BR(b\rightarrow s \gamma)=(4.3\pm 0.37 )\times 10^{-4}$.Comment: 12 pages (plain TeX), 2 postscript figures available upon request. UM-TH-93-20 , IP-ASTP-29-9

Effective Field Theories in R_xi gauges

In effective quantum field theories, higher dimensional operators can affect the canonical normalization of kinetic terms at tree level. These contributions for scalars and gauge bosons should be carefully included in the gauge fixing procedure, in order to end up with a convenient set of Feynman rules. We develop such a setup for the linear R_xi-gauges. It involves a suitable reduction of the operator basis, a generalized gauge fixing term, and a corresponding ghost sector. Our approach extends previous results for the dimension-six Standard Model Effective Field Theory to a generic class of effective theories with operators of arbitrary dimension.Comment: 16 pages, no figure

b→sγb \to s \gamma Decay in SU(2)L×SU(2)R×U(1)SU(2)_L \times SU(2)_R \times U(1) Extensions of the Standard Model

The rare radiative decay $b \to s \gamma$ is studied in $SU(2)_L \times SU(2)_R \times U(1)$ extensions of the Standard Model. Matching conditions for coefficients of operators appearing in the low energy effective Hamiltonian for this process are derived, and QCD corrections to these coefficients are analyzed. The $b \to s \gamma$ decay rate is then calculated and compared with the corresponding Standard Model result. We find that observable deviations from Standard Model predictions can occur in $SU(2)_L \times SU(2)_R \times U(1)$ theories for a reasonable range of parameter values.Comment: 17 pages with 5 figures not included but available upon request, CALT-68-1893, TUM-T31-52/9

Recalculation of QCD Corrections to b→sγb \to s \gamma Decay

We give a more complete calculation of $b \to s\gamma$ decay, including leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections from $M_{W}$ to $m_b$. We have included the full set of dimension-6 operators and corrected numerical mistakes of anomalous dimensions in a previous paper\cite{Cho}. Comparing with the calculations without QCD running from $m_{top}$ to $M_W$\cite{Mis}, the inclusive decay rate is found to be enhanced. At $m_t=150$GeV, it results in 12\% enhancement, and for $m_t=250$GeV, 15\% is found. The total QCD effect makes an enhanced factor of 4.2 at $m_t=150$GeV, and 3.2 for $m_t=250$GeV.Comment: 16 pages, 7 figures (uuencoded ps files), Changes of description. To appear in Phys. Rev.

The b→sγγb\to s\gamma\gamma transition in softly broken supersymmetry

We study the effect of supersymmetric contributions to the effective quark transition $b\to s\gamma\gamma$, including leading order QCD effects. We apply the discussion to the decay $B_s\to\gamma\gamma$. Even though one-particle irreducible contributions could play a role, numerical cancelations make the amplitude for the two-photon emission strongly correlated to the $b\to s\gamma$ amplitude which is sharply constrained by experiment. A quite general statement follows: as long as non-standard physics effects appear only in the matching of the Wilson coefficients of the standard effective operator basis, the deviations from the standard model expectations of the decay rates induced by $b\to s\gamma\gamma$ are bound to follow closely the corresponding deviations on $b\to s\gamma$. Effects of new physics are therefore bound to be small.Comment: Latex2e, RevTex, 22 pages, 8 eps figures, comments and references adde