Flavor Changing Neutral Currents involving Heavy Quarks with Four Generations

We study various FCNC involving heavy quarks in the Standard Model (SM) with a sequential fourth generation. After imposing $B\to X_s\gamma$, $B\to X_sl^+l^-$ and $Z\to b\bar{b}$ constraints, we find ${\cal B}(Z\to s\bar{b}+\bar{s}b)$ can be enhanced by an order of magnitude to $10^{-7}$, while $t\to cZ, cH$ decays can reach $10^{-6}$, which are orders of magnitude higher than in SM. However,these rates are still not observable for the near future.With the era of LHC approaching, we focus on FCNC decays involving fourth generation $b^\prime$ and $t^\prime$ quarks. We calculate the rates for loop induced FCNC decays $b^\prime\to bZ, bH, bg, b\gamma$, as well as t^\prime\to tZ,\tH, tg, t\gamma. If $|V_{cb'}|$ is of order $|V_{cb}| \simeq 0.04$, tree level $b^\prime\to cW$ decay would dominate, posing a challenge since $b$-tagging is less effective. For $|V_{cb'}| \ll |V_{cb}|$, $b'\to tW$ would tend to dominate, while $b'\to t^\prime W^*$ could also open for heavier $b'$, leading to thepossibility of quadruple-$W$ signals via $b'\bar b'\to b\bar b W^+W^-W^+W^-$. The FCNC $b'\to bZ, bH$ decays could still dominate if $m_{b'}$ is just above 200 GeV. For the case of $t'$, ingeneral $t^\prime\to bW$ would be dominant, hence it behaves like a heavy top. For both $b'$ and $t'$, except for the intriguing light $b'$ case, FCNC decays are in the $10^{-4} -10^{-2}$ range, and are quite detectable at the LHC.For a possible future ILC, we find the associated production of FCNC $e^+e^-\to b\bar s$, $t\bar c$ are below sensitivity, while $e^+e^-\to b^\prime\bar b$ and$t^\prime\bar t$ can be better probed.Tevatron Run-II can still probe the lighter $b'$ or $t'$ scenario. LHC would either discover the fourth generation and measure the FCNC rates, or rule out the fourth generation conclusively.Comment: 31 pages, 15 eps figures, version to appear in JHE

Supersymmetric Contributions to Bs->K+K-

Inspired by the existing calculation of B->piK decays in supersymmetry (SUSY), we evaluate the dominant SUSY contributions to Bs->K+K-. We show that the observables of this process can be significantly modified in the presence of SUSY. In particular, the branching ratio can be increased considerably compared to the prediction of the standard model (SM). The effect is even more dramatic for the CP-violating asymmetries A_dir and A_mix. These asymmetries, expected to be small in the SM (A_dir is predicted to take only positive values), change drastically with SUSY contributions. The measurement of these observables can therefore be used to detect the presence of physics beyond the SM, and put constraints on its parameters.Comment: 17 pages, 2 figures. This new version contains one added reference and some minor style change

Parents' preferences for the organisation of long-term follow-up of childhood cancer survivors

Parents take an important role in follow-up of young cancer survivors. We aimed to investigate (1) parents' preferences for organisation of follow-up (including content, specialists involved and models of care), and (2) parents' and children's characteristics predicting preference for generalist vs. specialist-led follow-up. We sent a questionnaire to parents of childhood cancer survivors aged 11-17 years. We assessed on a 4-point Likert scale (1-4), parents' preferences for organisation of long-term follow-up. Proposed models were: telephone/questionnaire, general practitioner (GP) (both categorised as generalist for regression analysis); and paediatric oncologist, medical oncologist or multidisciplinary team (MDT) (categorised as specialists). Of 284 contacted parents, 189 responded (67%). Parents welcomed if visits included checking for cancer recurrence (mean = 3.89), late effects screening (mean = 3.79), taking patients seriously (mean = 3.86) and competent staff (mean = 3.85). The preferred specialists were paediatric oncologists (mean = 3.73). Parents valued the paediatric oncologist model of care (mean = 3.49) and the MDT model (mean = 3.14) highest. Parents of children not attending clinic-based follow-up (OR = 2.97, p = .009) and those visiting a generalist (OR = 4.23, p = .007) favoured the generalist-led model. Many parents preferred a clinic-based model of follow-up by paediatric oncologists or a MDT. However, parents also valued the follow-up care model according to which their child is followed up

A first look at Landau-gauge propagators in G2 Yang-Mills theory

G_2 Yang--Mills theory is an interesting laboratory to investigate non-perturbative effects. On one hand, no conventional quark confinement via a linearly rising potential is present. On the other hand, its thermodynamic properties are similar to ordinary SU(N) Yang--Mills theory. Finally, it has been conjectured that gluons are removed from the physical spectrum in the same way as in SU(N) Yang--Mills theory. The last claim will be explored by determining the Landau-gauge ghost and gluon propagators, as well as the Faddeev--Popov operator eigenspectrum, in G_2 lattice gauge theory in two and three dimensions. The results are found to agree qualitatively with the SU(2) and SU(3) case. Therefore, the conjecture that Yang--Mills theories with different gauge groups are qualitatively similar on the level of their Landau gauge Green's functions is supported.Comment: 22 pages, 4 figures, 2 tables; in v2: One figure added, added statistics, extended discussion on some topics, various minor change

Employment Situation of Parents of Long-Term Childhood Cancer Survivors

BACKGROUND: Taking care of children diagnosed with cancer affects parents' professional life. The impact in the long-term however, is not clear. We aimed to compare the employment situation of parents of long-term childhood cancer survivors with control parents of the general population, and to identify clinical and socio-demographic factors associated with parental employment. METHODS: As part of the Swiss Childhood Cancer Survivor Study, we sent a questionnaire to parents of survivors aged 5-15 years, who survived ≥5 years after diagnosis. Information on control parents of the general population came from the Swiss Health Survey (restricted to men and women with ≥1 child aged 5-15 years). Employment was categorized as not employed, part-time, and full-time employed. We used generalized ordered logistic regression to determine associations with clinical and socio-demographic factors. Clinical data was available from the Swiss Childhood Cancer Registry. RESULTS: We included 394 parent-couples of survivors and 3'341 control parents (1'731 mothers; 1'610 fathers). Mothers of survivors were more often not employed (29% versus 22%; ptrend = 0.007). However, no differences between mothers were found in multivariable analysis. Fathers of survivors were more often employed full-time (93% versus 87%; ptrend = 0.002), which remained significant in multivariable analysis. Among parents of survivors, mothers with tertiary education (OR = 2.40, CI:1.14-5.07) were more likely to be employed. Having a migration background (OR = 3.63, CI: 1.71-7.71) increased the likelihood of being full-time employed in mothers of survivors. Less likely to be employed were mothers of survivors diagnosed with lymphoma (OR = 0.31, CI:0.13-0.73) and >2 children (OR = 0.48, CI:0.30-0.75); and fathers of survivors who had had a relapse (OR = 0.13, CI:0.04-0.36). CONCLUSION: Employment situation of parents of long-term survivors reflected the more traditional parenting roles. Specific support for parents with low education, additional children, and whose child had a more severe cancer disease could improve their long-term employment situation

Cytology interpretation after a change to HPV testing in primary cervical screening : observational study from the English pilot

Background Overcalling of abnormalities has been a concern for using cytology triage after positive high-risk human papillomavirus (HPV) tests in cervical screening. Methods The authors studied the detection of cytological and histological abnormalities at age 24 to 64 years, using data from the English HPV pilot. The pilot compared routine implementation of primary cervical screening based on cytology (N = 931,539), where HPV test results were not available before cytology reporting, with that based on HPV testing (N = 403,269), where cytology was only required after positive HPV tests. Results Revealed HPV positivity was associated with a higher direct referral to colposcopy after any abnormality (adjusted odds ratio [ORadj], 1.16; 95% confidence interval [CI], 1.14-1.18). Laboratories with higher direct referral referred fewer persistently HPV-positive women after early recall. The detection of high-grade cervical intraepithelial neoplasia (CIN2+) after direct referral increased with an ORadj of 1.17 (95% CI, 1.13-1.20) for informed versus uninformed cytology. Generally, the positive predictive value (PPV) of colposcopy for CIN2+ remained comparable under both conditions of interpreting cytology. In women 50 to 64 years old with high-grade dyskaryosis, however, the PPV increased from 71% to 83% after revealing HPV positivity (ORadj, 2.05; 95% CI, 1.43-2.93). Conclusions Quality-controlled cervical screening programs can avoid inappropriate overgrading of HPV-positive cytology

Low energy effects of neutrino masses

While all models of Majorana neutrino masses lead to the same dimension five effective operator, which does not conserve lepton number, the dimension six operators induced at low energies conserve lepton number and differ depending on the high energy model of new physics. We derive the low-energy dimension six operators which are characteristic of generic Seesaw models, in which neutrino masses result from the exchange of heavy fields which may be either fermionic singlets, fermionic triplets or scalar triplets. The resulting operators may lead to effects observable in the near future, if the coefficients of the dimension five and six operators are decoupled along a certain pattern, which turns out to be common to all models. The phenomenological consequences are explored as well, including their contributions to $\mu \to e \gamma$ and new bounds on the Yukawa couplings for each model.Comment: modifications: couplings in appendix B, formulas (121)-(122) on rare leptons decays (to match with published version) and consequently bounds in table

Prospects for heavy supersymmetric charged Higgs boson searches at hadron colliders

We investigate the production of a heavy charged Higgs boson at hadron colliders within the context of the MSSM. A detailed study is performed for all important production modes and basic background processes for the t\bar{t}b\bar{b} signature. In our analysis we include effects of initial and final state showering, hadronization, and principal detector effects. For the signal production rate we include the leading SUSY quantum effects at high \tan\beta>~ mt/mb. Based on the obtained efficiencies for the signal and background we estimate the discovery and exclusion mass limits of the charged Higgs boson at high values of \tan\beta. At the upgraded Tevatron the discovery of a heavy charged Higgs boson (MH^+ >~ 200 GeV) is impossible for the tree-level cross-section values. However, if QCD and SUSY effects happen to reinforce mutually, there are indeed regions of the MSSM parameter space which could provide 3\sigma evidence and, at best, 5\sigma charged Higgs boson discovery at the Tevatron for masses M_H^+<~ 300 GeV and M_H^+<~ 250 GeV, respectively, even assuming squark and gluino masses in the (500-1000) GeV range. On the other hand, at the LHC one can discover a H^+ as heavy as 1 TeV at the canonical confidence level of 5\sigma; or else exclude its existence at 95% C.L. up to masses ~ 1.5 TeV. Again the presence of SUSY quantum effects can be very important here as they may shift the LHC limits by a few hundred GeV.Comment: Latex2e, 44 pages, 15 figures, 6 tables, uses JHEP3.sty, axodraw.sty. Comments added. Discussion on QCD factors clarified. Added discussion on uncertainties. Change of presentation of Tables 4 and 5 and Fig.6. Results and conclusions unchanged. Version accepted in JHE

Pseudoscalar Higgs boson production associated with a single bottom quark at hadron colliders

We compute the complete next-to-leading order (NLO) SUSY-QCD corrections for the associated production of a pseudoscalar Higgs boson with a bottom quark via bottom-gluon fusion at the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron. We find that the NLO QCD correction in the MSSM reaches $40$ at the LHC and $45$ at the Tevatron in our chosen parameter space

Symmetries and Asymmetries of B -> K* mu+ mu- Decays in the Standard Model and Beyond

The rare decay B -> K* (-> K pi) mu+ mu- is regarded as one of the crucial channels for B physics as the polarization of the K* allows a precise angular reconstruction resulting in many observables that offer new important tests of the Standard Model and its extensions. These angular observables can be expressed in terms of CP-conserving and CP-violating quantities which we study in terms of the full form factors calculated from QCD sum rules on the light-cone, including QCD factorization corrections. We investigate all observables in the context of the Standard Model and various New Physics models, in particular the Littlest Higgs model with T-parity and various MSSM scenarios, identifying those observables with small to moderate dependence on hadronic quantities and large impact of New Physics. One important result of our studies is that new CP-violating phases will produce clean signals in CP-violating asymmetries. We also identify a number of correlations between various observables which will allow a clear distinction between different New Physics scenarios.Comment: 56 pages, 18 figures, 14 tables. v5: Missing factor in eqs. (3.31-32) and fig. 6 corrected. Minor misprints in eq. (2.10) and table A corrected. Conclusions unchange