1,800 research outputs found
Probing for Invisible Higgs Decays with Global Fits
We demonstrate by performing a global fit on Higgs signal strength data that
large invisible branching ratios Br_{inv} for a Standard Model (SM) Higgs
particle are currently consistent with the experimental hints of a scalar
resonance at the mass scale m_h ~ 124 GeV. For this mass scale, we find
Br_{inv} < 0.64 (95 % CL) from a global fit to individual channel signal
strengths supplied by ATLAS, CMS and the Tevatron collaborations. Novel tests
that can be used to improve the prospects of experimentally discovering the
existence of a Br_{inv} with future data are proposed. These tests are based on
the combination of all visible channel Higgs signal strengths, and allow us to
examine the required reduction in experimental and theoretical errors in this
data that would allow a more significantly bounded invisible branching ratio to
be experimentally supported. We examine in some detail how our conclusions and
method are affected when a scalar resonance at this mass scale has couplings
deviating from the SM ones.Comment: 32pp, 15 figures v2: JHEP version, ref added & comment added after
Eq.
Theory and phenomenology of two-Higgs-doublet models
We discuss theoretical and phenomenological aspects of two-Higgs-doublet
extensions of the Standard Model. In general, these extensions have scalar
mediated flavour changing neutral currents which are strongly constrained by
experiment. Various strategies are discussed to control these flavour changing
scalar currents and their phenomenological consequences are analysed. In
particular, scenarios with natural flavour conservation are investigated,
including the so-called type I and type II models as well as lepton-specific
and inert models. Type III models are then discussed, where scalar flavour
changing neutral currents are present at tree level, but are suppressed by
either specific ansatze for the Yukawa couplings or by the introduction of
family symmetries. We also consider the phenomenology of charged scalars in
these models. Next we turn to the role of symmetries in the scalar sector. We
discuss the six symmetry-constrained scalar potentials and their extension into
the fermion sector. The vacuum structure of the scalar potential is analysed,
including a study of the vacuum stability conditions on the potential and its
renormalization-group improvement. The stability of the tree level minimum of
the scalar potential in connection with electric charge conservation and its
behaviour under CP is analysed. The question of CP violation is addressed in
detail, including the cases of explicit CP violation and spontaneous CP
violation. We present a detailed study of weak basis invariants which are odd
under CP. A careful study of spontaneous CP violation is presented, including
an analysis of the conditions which have to be satisfied in order for a vacuum
to violate CP. We present minimal models of CP violation where the vacuum phase
is sufficient to generate a complex CKM matrix, which is at present a
requirement for any realistic model of spontaneous CP violation.Comment: v3: 180 pages, 506 references, new chapter 7 with recent LHC results;
referee comments taken into account; submitted to Physics Report
One-Loop Calculation of the Oblique S Parameter in Higgsless Electroweak Models
We present a one-loop calculation of the oblique S parameter within Higgsless
models of electroweak symmetry breaking and analyze the phenomenological
implications of the available electroweak precision data. We use the most
general effective Lagrangian with at most two derivatives, implementing the
chiral symmetry breaking SU(2)_L x SU(2)_R -> SU(2)_{L+R} with Goldstones,
gauge bosons and one multiplet of vector and axial-vector massive resonance
states. Using the dispersive representation of Peskin and Takeuchi and imposing
the short-distance constraints dictated by the operator product expansion, we
obtain S at the NLO in terms of a few resonance parameters. In
asymptotically-free gauge theories, the final result only depends on the
vector-resonance mass and requires M_V > 1.8 TeV (3.8 TeV) to satisfy the
experimental limits at the 3 \sigma (1\sigma) level; the axial state is always
heavier, we obtain M_A > 2.5 TeV (6.6 TeV) at 3\sigma (1\sigma). In
strongly-coupled models, such as walking or conformal technicolour, where the
second Weinberg sum rule does not apply, the vector and axial couplings are not
determined by the short-distance constraints; but one can still derive a lower
bound on S, provided the hierarchy M_V < M_A remains valid. Even in this less
constrained situation, we find that in order to satisfy the experimental limits
at 3\sigma one needs M_{V,A} > 1.8 TeV.Comment: 34 pages, 9 figures. Version published in JHEP. Some references and
sentences have been added to facilitate the discussio
Effect of exercise training before and after bariatric surgery: A systematic review and meta-analysis
We aimed to assess the effectiveness of exercise training programs in adults with severe obesity undergoing bariatric surgery. A systematic search of controlled trials published up to October 2019 that assigned participants to either a preoperative or postoperative exercise training group or a nonexercise group was performed. Meta-analyses were conducted using random-effects models. Twenty-two training programs were assessed (18 performed after bariatric surgery). The effect of preoperative exercise training on postsurgery outcomes was reported in only one study. Compared with the control condition without exercise, postoperative exercise training led to higher weight loss (Nâ=â14, mean difference [95% CI]â=ââ1.8 [â3.2; â0.4] kg, Pâ=â0.01), fat loss (Nâ=â9, Pâ=â0.01), increase in VO2max (Nâ=â8, Pâ<â0.0001), and increase in muscle strength (Nâ=â9, Pâ<â0.0001). No significant effect was found on lean body mass (Nâ=â11). Preliminary evidence suggests a beneficial effect of postoperative exercise training on bone mineral density (Nâ=â3, Pâ<â0.001) and weight maintenance after the end of the intervention (Nâ=â2, Pâ<â0.001) but no significant effect on quality of life (Nâ=â2), habitual physical activity (Nâ=â2), or cardiometabolic outcomes (Nâ<â4). In conclusion, exercise training performed after bariatric surgery improves physical fitness and leads to a small additional weight and fat loss and may prevent bone loss and weight regain after bariatric surgery
Effect of exercise on cardiometabolic health of adults with overweight or obesity: Focus on blood pressure, insulin resistance, and intrahepatic fatâA systematic review and metaâanalysis
This systematic review examined the impact of exercise intervention programs on selected cardiometabolic health indicators in adults with overweight or obesity. Three electronic databases were explored for randomized controlled trials (RCTs) that included adults with overweight or obesity and provided exerciseâtraining interventions. Effects on blood pressure, insulin resistance (homeostasis model of insulin resistance, HOMAâIR), and magnetic resonance measures of intrahepatic fat in exercise versus control groups were analyzed using random effects metaâanalyses. Fiftyâfour articles matched inclusion criteria. Exercise training reduced systolic and diastolic blood pressure (mean difference, MDâ=ââ2.95âmmHg [95% CI â4.22, â1.68], pâ<â0.00001, I2 =â63% and MDâ=ââ1.93âmmHg [95% CI â2.73, â1.13], pâ<â0.00001, I2 =â54%, 60 and 58 study arms, respectively). Systolic and diastolic blood pressure decreased also when considering only subjects with hypertension. Exercise training significantly decreased HOMAâIR (standardized mean difference, SMDâ=ââ0.34 [â0.49, â0.18], pâ<â0.0001, I2â=â48%, 37 study arms), with higher effect size in subgroup of patients with type 2 diabetes (SMDâ=ââ0.50 [95% CI: â0.83, â0.17], pâ=â0.003, I2â=â39%). Intrahepatic fat decreased significantly after exercise interventions (SMDâ=ââ0.59 [95% CI: â0.78, â0.41], pâ<â0.00001, I2 =â0%), with a larger effect size after highâintensity interval training. In conclusion, exercise training is effective in improving cardiometabolic health in adults with overweight or obesity also when living with comorbitidies
Effect of exercise training interventions on energy intake and appetite control in adults with overweight or obesity: A systematic review and meta-analysis
This systematic review examined the impact of exercise training interventions on energy intake (EI) and appetite control in adults with overweight/obesity (â„18âyears including older adults). Articles were searched up to October 2019. Changes in EI, fasting appetite sensations, and eating behavior traits were examined with random effects meta-analysis, and other outcomes were synthesized qualitatively. Forty-eight articles were included (median [range] BMIâ=â30.6 [27.0â38.4] kg/m2). Study quality was rated as poor, fair, and good in 39, seven, and two studies, respectively. Daily EI was assessed objectively (Nâ=â4), by self-report (Nâ=â22), with a combination of the two (Nâ=â4) or calculated from doubly labeled water (Nâ=â1). In studies rated fair/good, no significant changes in pre-post daily EI were found and a small but negligible (SMDâ<â0.20) postintervention difference when compared with no-exercise control groups was observed (five study arms; MDâ=â102 [1, 203] kcal). There were negligible-to-small pre-post increases in fasting hunger and dietary restraint, decrease in disinhibition, and some positive changes in satiety and food reward/preferences. Within the limitations imposed by the quality of the included studies, exercise training (median duration of 12âweeks) leads to a small increase in fasting hunger and a small change in average EI only in studies rated fair/good. Exercise training may also reduce the susceptibility to overconsumption (PROSPERO: CRD42019157823)
Effect of different types of regular exercise on physical fitness in adults with overweight or obesity: Systematic review and metaâanalyses
This systematic review examined the effect of exercise training interventions on physical fitness in adults with overweight or obesity and compared the effectiveness of different types of exercise training. Four electronic databases were searched. Articles were included if they described randomized controlled trials of exercise training interventions and their effect on maximal oxygen consumption or muscle strength in adults with overweight or obesity. Changes in outcome parameters were analyzed using random effects metaâanalyses for different training types (aerobic, resistance, combined aerobic plus resistance, and highâintensity interval training). Eightyâeight articles satisfied the inclusion criteria of which 66 (3964 participants) could be included in the metaâanalyses. All training types increased VO2max (mean difference 3.82 ml/min/kg (95% CI 3.17, 4.48), Pâ<â0.00001; I2 =â48%). In direct comparisons, resistance training was less effective in improving VO2max than aerobic training, HIIT was slightly more effective than aerobic training, and no difference between aerobic and combined aerobic plus resistance training was found. For muscle strength benefits, incorporation of resistance exercise in the training program is indicated. Exercise training increases VO2max and muscle strength in adults with overweight or obesity. Differences between training types should be weighed with other needs and preferences when health professionals advise on exercise training to improve physical fitness
Exercise training in the management of overweight and obesity in adults: Synthesis of the evidence and recommendations from the European Association for the Study of Obesity Physical Activity Working Group
There is a need for updated practice recommendations on exercise in the management of overweight and obesity in adults. We summarize the evidence provided by a series of seven systematic literature reviews performed by a group of experts from across Europe. The following recommendations with highest strength (Grade A) were derived. For loss in body weight, total fat, visceral fat, intra-hepatic fat, and for improvement in blood pressure, an exercise training program based on aerobic exercise at moderate intensity is preferentially advised. Expected weight loss is however on average not more than 2 to 3âkg. For preservation of lean mass during weight loss, an exercise training program based on resistance training at moderate-to-high intensity is advised. For improvement in insulin sensitivity and for increasing cardiorespiratory fitness, any type of exercise training (aerobic, resistance, and combined aerobic or resistance) or high-intensity interval training (after thorough assessment of cardiovascular risk and under supervision) can be advised. For increasing muscular fitness, an exercise training program based preferentially on resistance training alone or combined with aerobic training is advised. Other recommendations deal with the beneficial effects of exercise training programs on energy intake and appetite control, bariatric surgery outcomes, and quality of life and psychological outcomes in management of overweight and obesity
Search for rare quark-annihilation decays, B --> Ds(*) Phi
We report on searches for B- --> Ds- Phi and B- --> Ds*- Phi. In the context
of the Standard Model, these decays are expected to be highly suppressed since
they proceed through annihilation of the b and u-bar quarks in the B- meson.
Our results are based on 234 million Upsilon(4S) --> B Bbar decays collected
with the BABAR detector at SLAC. We find no evidence for these decays, and we
set Bayesian 90% confidence level upper limits on the branching fractions BF(B-
--> Ds- Phi) Ds*- Phi)<1.2x10^(-5). These results
are consistent with Standard Model expectations.Comment: 8 pages, 3 postscript figues, submitted to Phys. Rev. D (Rapid
Communications
Observation of associated near-side and away-side long-range correlations in âsNN=5.02ââTeV proton-lead collisions with the ATLAS detector
Two-particle correlations in relative azimuthal angle (ÎÏ) and pseudorapidity (Îη) are measured in âsNN=5.02ââTeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1ââÎŒb-1 of data as a function of transverse momentum (pT) and the transverse energy (ÎŁETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Îη|<5) ânear-sideâ (ÎÏâŒ0) correlation that grows rapidly with increasing ÎŁETPb. A long-range âaway-sideâ (ÎÏâŒÏ) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ÎŁETPb, is found to match the near-side correlation in magnitude, shape (in Îη and ÎÏ) and ÎŁETPb dependence. The resultant ÎÏ correlation is approximately symmetric about Ï/2, and is consistent with a dominant cosâĄ2ÎÏ modulation for all ÎŁETPb ranges and particle pT
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