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Dennis Silverman

Publications and source records attributed to Dennis Silverman.

10 recordsLinked to original sources
arXiv2003

Effects of Right-handed Gauge Bosons in B-Bbar Mixing and CP Violation

In the Left-Right Symmetric Model (LRSM), box diagrams involving the charged right-handed gauge boson W_R may affect B-Bbar mixing as well as CP asymmetries in neutral B decays. The smallness of the epsilon_K parameter in the neutral K-meson system places severe constraints on the right-handed quark mixing matrix V^R, and reduces the number of its effective phases to one. W_R exchange gives a large contribution to B-Bbar mixing when the mass of the W_R boson is up to or higher than 8 TeV, depending on the V^R case, the B_d,s meson, and the asymmetry. The allowed regions of the CP violating asymmetries sin(2beta), sin(gamma), sin(2alpha), and sin(2phi_s), as well as x_s, are calculated as a function of the W_R mass. The results of the LRSM other than for the well measured sin(2beta) show allowable regions that are much broader than that for the Standard Model, showing that new experiments can indicate a presence of new physics, or significantly push up the limits on the W_R mass.

hep-ph↗
arXiv2002

Iso-singlet Down Quark Mixing And CP Violation Experiments

We confront the new physics models with extra iso-singlet down quarks in the new CP violation experimental era with $\sin{(2β)}$ and $ε'/ε$ measurements, $K^+ \to π^+ ν\barν$ events, and $x_s$ limits. The closeness of the new experimental results to the standard model theory requires us to include full SM amplitudes in the analysis. In models allowing mixing to a new isosinglet down quark, as in E$_6$, flavor changing neutral currents are induced that allow a $Z^0$ mediated contribution to $B-\bar B$ mixing and which bring in new phases. In $(ρ,η)$, $(x_s,\sin{(γ)})$, and $(x_s, \sin{(2ϕ_s)})$ plots we still find much larger regions in the four down quark model than in the SM, reaching down to $η\approx 0$, $0 \leq \sin{(γ)} \leq 1$, $-.75 \leq \sin{(2α)} \leq 0.15$, and $\sin{(2ϕ_s)}$ down to zero, all at 1$σ$. We elucidate the nature of the cancellation in an order $λ^5$ four down quark mixing matrix element which satisfies the experiments and reduces the number of independent angles and phases. We also evaluate tests of unitarity for the $3\times3$ CKM submatrix.

hep-ph↗
arXiv2001

W_R Effects on CP Asymmetries in B Meson Decays

After we have limited elements of the right-handed CKM matrix to satisfy the bounds for CP violation epsilon_K in K meson systems, the right-handed charged current gauge boson W_R is shown to substantially affect CP asymmetries in B systems. A joint chi-squared analysis is applied to B-Bbar mixing to constrain the right-handed CKM matrix elements. In (sin(2alpha), sin(2beta)), (x_s, sin(gamma)), (rho-eta), and (x_s, sin(2phi_s)) plots in the presence of the W_R boson, we find larger allowed experimental regions that can distinguish this model from the standard model.

hep-ph↗
arXiv1999

Joint Bayesian Treatment of Poisson and Gaussian Experiments in a Chi-squared Statistic

Bayesian Poisson probability distributions for the average n can be analytically converted into equivalent chi-squared distributions. These can then be combined with other Gaussian or Bayesian Poisson distributions to make a total chi-squared distribution. This allows the usual treatment of chi-squared contours but now with both Poisson and Gaussian statistics experiments. This is illustrated with the case of neutrino oscillations.

physics.data-an↗
arXiv1998

The Full Range of Predictions for B Physics From Iso-singlet Down Quark Mixing

We extend the range of predictions of the isosinglet (or vector) down quark model to the fully allowed physical ranges, and also update this with the effect of new physics constraints. We constrain the present allowed ranges of sin(2*beta) and sin(2*alpha), gamma, x_s, and A_{B_s}. In models allowing mixing to a new isosinglet down quark (as in E_6) flavor changing neutral currents are induced that allow a Z^0 mediated contribution to B-Bbar mixing and which bring in new phases. In (rho, eta), (x_s, sin(gamma)), and (x_s, A_{B_s}) plots for the extra isosinglet down quark model which are herein extended to the full physical range, we find new allowed regions that will require experiments on sin(gamma) and/or x_s to verify or to rule out an extra down quark contribution.

hep-ph↗
arXiv1996

Effects of Anomalous Couplings of Quarks on Prompt Photon Production

Prompt photon production is sensitive to the anomalous couplings of gluons to quarks, because it is mainly produced by quark-gluon scattering. We will examine the effects of the anomalous chromoelectric and chromomagnetic dipole moment couplings of quarks on prompt photon production. Using the data collected by CDF and D0 at the Fermilab Tevatron we put a bound on these anomalous couplings. We also estimate the sensitivity of various future high energy collider experiments to these anomalous couplings.

hep-ph↗
arXiv1996

Limits on Anomalous Couplings of Quarks From Prompt Photon Data

Prompt photon production has been known to be a sensitive probe to the gluon luminosity inside a hadron because it is mainly produced by quark-gluon scattering. For the same reason prompt photon production should also be sensitive to the anomalous couplings of gluons to quarks. We will examine the effects of two specific anomalous couplings -- chromoelectric and chromomagnetic dipole moments of quarks -- on the prompt photon production. Using the data collected by CDF and D0 at the Tevatron we put a bound on the these anomalous couplings.

hep-ph↗
arXiv1996

Anomalous Chromomagnetic Moments of Quarks and Large Transverse Energy Jets

We consider the jet cross sections for gluons coupling to quarks with an anomalous chromomagnetic moment. We then apply this to the deviation and bounds from QCD found in the CDF and D0 Fermilab data, respectively, to find a range of possible values for the anomalous moments. The quadratic and quartic terms in the anomalous moments can fit to the rise of a deviation with transverse energy. Since previous analyses have been done on the top quark total cross section, here we assume the same moment on all quarks except the top and find the range $|κ'| \equiv |κ/(2 m_q)| = 1.0\pm 0.3$ TeV$^{-1}$ for the CDF data. Assuming the anomalous moment is present only on a charm or bottom quark which is pair produced results in a range $|κ'_{b,c}| = 3.5 \pm 1.0 $ TeV$^{-1}$. The magnitudes here are compared with anomalous magnetic moments that could account for $R_b$ and found to be in the same general range, as well as not inconsistent with LEP and SLD bounds on $ΔΓ_{\text{had}}$.

hep-ph↗
arXiv1995

B Factory Constraints on Isosinglet Down Quark Mixing, and Predictions For Other CP Violating Experiments

In the main part of the paper we project forward to having $B$ factory determinations of $\sin(2β)$ and $\sin(2α)$, for which we take several values. First, we use a joint $χ^2$ analysis of CKM experiments to constrain CKM matrix elements in the standard model, and experiments on the angles $α$, $β$, and $γ$, and on $x_s$ and null $CP$ asymmetries. Then we invoke mixing to a new isosinglet down quark (as in E$_6$) which induces FCNC that allow a $Z^0$ mediated contribution to $B-\bar B$ mixing and which brings in new phases. We then repeat the $χ^2$ analysis, now including experimental constraints from FCNC as well, finding much larger ranges of prediction for the $B$ factory. We then add projected $B$ factory results on $\sin(2β)$ and $\sin(2α)$ and repeat both analyses. In $(ρ,η)$ and $(x_s,\sin{(γ)})$ plots for the extra isosinglet down quark model, we find multiple regions that will require experiments on $\sin{(γ)}$ and/or $x_s$ to decide between and possibly to effectively bound out the extra down quark contribution.

hep-ph↗