HEP Phenomenology·hep-ph

Tue·Sep 15, 2015Tuesday·September 15, 2015

46 papers—29 primary·17 cross-listed·reconstructed*

01*
New probes for bino dark matter with coannihilation at the LHC
Hidetoshi Otono🇯🇵
It has been widely known that bino-like dark matter in supersymmetric theories suffers from over-production. The situation can be improved if the gluino or wino has a mass of O(10) GeV heavier than the bino, sufficiently reducing the bino abundance through co-annihilation. In this scenario, the gluino decays to the bino via squark exchange, and the wino decays to the bino via higgsino exchange. In split SUSY models favoured after the Higgs discovery, the intermediate particles in these decays would be much heavier than gauginos, suppressing the decay of the gluino and wino. This, in addition to the small mass differences, results in long lifetimes for the gluino and wino. We show that searches performed at the LHC for long-lived particles with displaced vertices offer a powerful method to test this scenario.
hep-phhep-exPoS(2015)·1 citation
02*
Continuum-Mediated Dark Matter-Baryon Scattering
Andrey Katz🇨🇭 · Matthew Reece🇺🇸 · Aqil Sajjad🇺🇸
Many models of dark matter scattering with baryons may be treated either as a simple contact interaction or as the exchange of a light mediator particle. We study an alternative, in which a continuum of light mediator states may be exchanged. This could arise, for instance, from coupling to a sector which is approximately conformal at the relevant momentum transfer scale. In the non-relativistic effective theory of dark matter-baryon scattering, which is useful for parametrizing direct detection signals, the effect of such continuum mediators is to multiply the amplitude by a function of the momentum transfer q, which in the simplest case is just a power law. We develop the basic framework and study two examples: the case where the mediator is a scalar operator coupling to the Higgs portal (which turns out to be highly constrained) and the case of an antisymmetric tensor operator $O_{μν}$ that mixes with the hypercharge field strength and couples to dark matter tensor currents, which has an interesting viable parameter space. We describe the effect of such mediators on the cross sections and recoil energy spectra that could be observed in direct detection.
hep-phastro-ph.COPhys.Dark Univ.(2016)·21 citations
03*
Revisiting LHC gluino mass bounds through radiative decays using MadAnalysis 5
G. Chalons🇫🇷 · D. Sengupta🇫🇷
The ATLAS and CMS experiments at the CERN LHC have collected about 25 inverse femtobarns (fb) of data each at the end of their 8 TeV run, and ruled out a huge swath of parameter space in the context of Minimally Supersymmetric Standard Model (MSSM). Limits on masses of the gluino have been pushed to above 1 TeV. These limits are however extremely model dependent and do not always reflect the level of exclusion. So far the limits on the gluino mass using the simplified model approach only constrained its value using its three-body decays. We show in this work that already existing ATLAS and CMS analysis can also constrain the radiative gluino decay mode and we derived improved mass limits in particular when the mass difference between the LSP and the gluino is small.
hep-phhep-ex0 citations
04*
Revisiting Big-Bang Nucleosynthesis Constraints on Dark-Matter Annihilation
Masahiro Kawasaki🇯🇵 · Kazunori Kohri🇯🇵 · Takeo Moroi🇯🇵 · Yoshitaro Takaesu🇯🇵
We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.
hep-phastro-ph.COPLB(2015)·59 citations
05*
MadDM: New Dark Matter Tool in the LHC era
Mihailo Backovic🇧🇪 · Antony Martini🇧🇪 · Kyoungchul Kong🇺🇸 · Olivier Mattelaer🇬🇧 · Gopolang Mohlabeng🇺🇸
We present the updated version of MadDM, a new dark matter tool based on MadGraph5_aMC@NLO framework. New version includes direct detection capability in addition to relic abundance computation. In this article, we provide short description of the implementation of relevant effective operators and validations against existing results in literature.
hep-phAIP Conf.Proc.(2016)·20 citations
06*
Bottom Baryon Decays to Pseudoscalar Meson and Pentaquark
Hai-Yang Cheng🇹🇼 · Chun-Khiang Chua🇹🇼
Based on SU(3) flavor symmetry, we decompose the decay amplitudes of bottom baryon decays to a pseudoscalar meson and an octet (a decuplet) pentaquark in terms of three (two) invariant amplitudes $T_{1}$ and $T_{2, 3}$ ( $T ~_{1}$ and $T ~_{2}$ ) corresponding to external $W$ -emission and internal $W$ -emission diagrams, respectively. For antitriplet bottom baryons $Λ_{b}^{0}, Ξ_{b}^{0}$ and $Ξ_{b}^{-}$ , their decays to a decuplet pentaquark proceed only through the internal $W$ -emission diagram. Assuming the dominance from the external $W$ -emission amplitudes, we present an estimate of the decay rates relative to $Λ_{b}^{0} \to P_{p}^{+} K^{-}$ , where $P_{p}^{+}$ is the hidden-charm pentaquark with the same light quark content as the proton. Hence, our numerical results will provide a very useful guideline to the experimental search for pentaquarks in bottom baryon decays. For example, $Ξ_{b}^{0} \to P_{Σ^{+}} K^{-}$ , $Ξ_{b}^{-} \to P_{Σ^{-}} K ˉ^{0}$ , $Ω_{b}^{-} \to P_{Ξ^{-}} K ˉ^{0}$ and $Ω_{b}^{-} \to P_{Ξ^{0}} K^{-}$ may have rates comparable to that of $Λ_{b}^{0} \to P_{p}^{+} K^{-}$ and these modes should be given the higher priority in the experimental searches for pentaquarks.
hep-phhep-exPRD(2015)·54 citations
07*
Fermion Masses and Leptogenesis from The Left-Right Symmetric Model
Wei-Min Yang🇨🇳
The paper suggests a left-right mirror symmetric model with the flavor symmetries $Z_{3 L} \otimes Z_{3 R}$ . It can simultaneously accommodate the standard model, neutrino physics and the baryon asymmetry. The fermion masses and $C P$ violation originate from vacuum spontaneous breaking of the flavor field. The baryon asymmetry is implemented through the leptogenesis which is related to the lepton $C P$ violation. The model can naturally and correctly reproduce all kinds of experimental data, in particular, all of the values of the fermion masses and mixings are accurately fitted by the fewer parameters. Finally, it is also feasible and promising to test the model in future experiments.
hep-ph0 citations
08*
Connecting amplitudes in different gauges beyond perturbation theory: a canonical flow approach
Andrea Quadri🇮🇹
Physical quantities in gauge theories have to be gauge-independent. However their evaluation can be greatly simplified by working in particular gauges. Since physical quantities have to be gauge invariant, it is important to establish an approach allowing the comparison of computations carried out in different gauges even beyond perturbation theory. We show that the dependence on the gauge parameter $α = 0$ in Yang-Mills theories is controlled by a canonical flow that explicitly solves the Nielsen identities of the model. Green's functions in the $α = 0$ gauge are given by amplitudes evaluated in the theory at $α = 0$ (e.g., in the example of Lorentz-covariant gauges, in terms of Landau gauge amplitudes) plus some contributions induced by the $α = 0$ -dependence of the generating functional of the canonical flow. Explicit formulas are presented and an application of the formalism to the gluon propagator is discussed.
hep-phhep-thPoS(2015)·0 citations
09*
LHC searches for heavy neutral Higgs bosons with a top jet substructure analysis
Ning Chen🇨🇳 · Jinmian Li🇦🇺 · Yandong Liu🇨🇳
We study the LHC searches for the heavy $C P$ -odd Higgs boson $A$ and $C P$ -even Higgs boson $H$ in the context of general two-Higgs-doublet model. Specifically, we consider the decay mode of $A / H \to t t ˉ$ through the $b b ˉ$ or $t t ˉ$ associated production channels. In the so-called "alignment limit" of the two-Higgs-doublet model, this decay mode can be the most dominant one. By employing the HEPTopTagger and the multi-variable-analysis method, we present the search sensitivities for both $C P$ -odd Higgs boson $A$ and $C P$ -even Higgs boson $H$ via these channels at the high-luminosity LHC runs.
hep-phPRD(2016)·14 citations
10*
CP Asymmetries in Many-Body Final States in Beauty & Charm Transitions
I.I. Bigi🇺🇸
Our community has focused on two-body final states in $B$ & $D$ decays. The SM produces at least the leading source of CP violation in $B$ transitions, none has been established yet in charm decays. It is crucial to measure three- and four-body FS with accuracy and to compare with predictions based on refined theoretical tools. Correlations between different final states (FS) based on CPT invariance are often not obvious, how to apply them and where. We have to probe regional asymmetries and use refined parametrization of the CKM matrix. One uses (broken) U- & V-spin symmetries for spectroscopy. The situations with weak decays of hadrons are much more complex. The impact of strong re-scattering is large, and it connects U- \& V-spin symmetries. Drawing diagrams often does not mean we understand the underlying dynamics. We have to probe the decays of beauty \& charm baryons. I discuss the `strategies' more than the `tactics'.
hep-ph7 citations
11*
Into the multi-TeV scale with a Higgs golden ratio
Abdelhak Djouadi🇫🇷 · Jérémie Quevillon🇬🇧 · Roberto Vega-Morales🇫🇷
With the upgrade of the LHC, the couplings of the observed Higgs particle to fermions and gauge bosons will be measured with a much higher experimental accuracy than current measurements, but will still be limited by an order 10% theoretical uncertainty. In this paper, we re-emphasize the fact that the ratio of Higgs signal rates into two photons and four leptons, $D_{γ γ} = σ (pp \to H \to γ γ) / σ (pp \to H \to Z Z^{*} \to 4 ℓ^{\pm})$ can be made free of these ambiguities. Its measurement would be limited only by the statistical and systematic errors, which can in principle be reduced to the percent level at a high-luminosity LHC. This decay ratio would then provide a powerful probe of new physics effects in addition to high precision electroweak observables or the muon g-2. As an example, we show that the Higgs couplings to top quarks and vector bosons can be constrained at the percent level and that new Higgs or supersymmetric particles that contribute to the H $γ γ$ loop can be probed up to masses in the multi-TeV range and possibly larger than those accessible directly.
hep-phhep-exPLB(2016)·22 citations
12*
Relating LHC event rates to supersymmetric Grand Unified Theories containing $S U (5)$
Björn Herrmann🇫🇷 · Sylvain Fichet🇧🇷 · Yannick Stoll🇫🇷
We elaborate on a recently found $S U (5)$ relation confined to the up-(s)quark flavour space, that remains immune to large quantum corrections up to the TeV scale. We investigate the possibilities opened by this new window on the GUT scale in order to find TeV-scale $S U (5)$ tests realizable at the LHC. We present a variety of tests, which appear as relations among observables involving flavour violation or chirality flips and rely on the techniques of top polarimetry, charm-tagging, or Higgs detection from cascade decays. We discuss the cases of natural Supersymmetry and top-charm Supersymmetry as example cases. We find that $O (10)$ to $O (100)$ events are needed to obtain 50\% of relative precision at 3 $σ$ significance for all proposed tests.
hep-phPoS(2015)·0 citations
13*
Inhomogeneous and Homogeneous Renormalization Group Equations for the Effective Potential
H. I. Alrebdi🇸🇦 · H. A. Alhendi🇸🇦 · T. Barakat🇸🇦
The inhomogeneous renormalization group equation for the effective potential is rederived. It is shown that when the effective potential is normalized by the normalization condition on the generating functional, its renormalization group equation is homogeneous. This is demonstrated in the case of massive $ϕ^{4}$ -theory. We also show that for the case of spontaneous symmetry breaking, the normalized effective potential is completely different from the symmetric case, though the two cases satisfy the same RGE with the same RG-functions. It is concluded that the vacuum energy density arises only in the case of SSB.
hep-ph0 citations
14*
Scaling properties of inclusive W $^{\pm}$ production at hadron colliders
François Arleo🇫🇷 · Émilien Chapon🇫🇷 · Hannu Paukkunen🇫🇮
We consider the hadroproduction of W gauge bosons in their leptonic decay mode. Starting from the leading-order expressions, we show that by defining a suitable scaling variable the centre-of-mass dependence of the cross sections at the LHC energies can be essentially described by a simple power law. The scaling exponent is directly linked to the small- $x$ behaviour of parton distribution functions (PDF) which, at the high virtualities involved in W production, is largely dictated by QCD evolution equations. This entails a particularly simple scaling law for the lepton charge asymmetry and also predicts that measurements in different collision systems (p-p, p- $p ˉ$ , p-Pb Pb-Pb) are straightforwardly related. The expectations are compared with the existing data and a very good overall agreement is observed. It is shown that the PDF uncertainty in certain cross-section ratios between nearby centre-of-mass energies can be significantly reduced by taking the ratios at fixed value of scaling variable instead of fixed rapidity.
hep-phhep-exnucl-exnucl-thEPJC(2016)·12 citations
15*
Symmetry violations in nuclear and neutron $β$ decay
K.K. Vos🇳🇱 · H.W. Wilschut🇳🇱 · R.G.E. Timmermans🇳🇱
The role of $β$ decay as a low-energy probe of physics beyond the Standard Model is reviewed. Traditional searches for deviations from the Standard Model structure of the weak interaction in $β$ decay are discussed in the light of constraints from the LHC and the neutrino mass. Limits on the violation of time-reversal symmetry in $β$ decay are compared to the strong constraints from electric dipole moments. Novel searches for Lorentz symmetry breaking in the weak interaction in $β$ decay are also included, where we discuss the unique sensitivity of $β$ decay to test Lorentz invariance. We end with a roadmap for future $β$ -decay experiments.
hep-phhep-exnucl-exnucl-thRMP(2015)·71 citations
16*
Reflecting disk with black edge
S.M.Troshin🇷🇺 · N.E. Tyurin🇷🇺
We discuss geometrical picture of hadron interactions and, in particular, the presence of energy--invariant edge in elastic scattering resulting from a transition to the reflective scattering mode which is supported by the recent LHC data. The energy-invariant edge represents a black ring around the reflecting disk.
hep-phMod.Phys.Lett.A(2016)·9 citations
17*
Probing anomalous couplings using di-Higgs production in electron-proton collisions
Mukesh Kumar🇿🇦 · Xifeng Ruan🇿🇦 · Rashidul Islam🇮🇳 · Alan S. Cornell🇿🇦 · Max Klein🇬🇧 · Uta Klein🇬🇧 · Bruce Mellado🇿🇦
A proposed high energy Future Circular Hadron-Electron Collider would provide sufficient energy in a clean environment to probe di-Higgs production. Using this channel we show that the azimuthal angle correlation between the missing transverse energy and the forward jet is a very good probe for the non-standard $hhh$ and $hhW W$ couplings. We give the exclusion limits on these couplings as a function of integrated luminosity at a $95$ \% C.L. using the fiducial cross sections. With appropriate error fitting methodology we find that the Higgs boson self coupling could be measured to be $g_{hhh}^{(1)} = 1.0 0_{- 0.17 (0.12)}^{+ 0.24 (0.14)}$ of its expected Standard Model value at $s = 3.5 (5.0)$ TeV for an ultimate 10 ab $^{- 1}$ of integrated luminosity.
hep-phPLB(2017)·38 citations
18*
Doped Parton Distributions
Valerio Bertone🇬🇧 · Stefano Carrazza🇮🇹 · Juan Rojo🇬🇧
Calculations of high-energy processes involving the production of b-quarks are typically performed in two different ways, the massive four-flavour scheme (4FS) and the massless five-flavour scheme (5FS). For processes where the combination of the 4FS and 5FS results into a matched calculation is technically difficult, it is possible to define a hybrid scheme known as the doped scheme, where above the b-quark threshold the strong coupling runs with $n_{f} = 5$ , as in the massless calculation, while the DGLAP splitting functions are those of the $n_{f} = 4$ scheme. In this contribution we present NNPDF3.0 PDF sets in this doped scheme, compare them with the corresponding 4FS and 5FS sets, and discuss their relevance for LHC phenomenology.
hep-phhep-ex5 citations
19*
Scalar dark matter in the B-L model
Werner Rodejohann🇩🇪 · Carlos E. Yaguna🇩🇪
The B-L extension of the Standard Model requires the existence of right-handed neutrinos and naturally realizes the seesaw mechanism of neutrino mass generation. We study the possibility of explaining the dark matter in this model with an additional scalar field that is a singlet of the Standard Model but charged under $U (1)_{B - L}$ . An advantage of this scenario is that the stability of the dark matter can be guaranteed by appropriately choosing its B-L charge, without the need of an extra ad hoc discrete symmetry. We investigate in detail the dark matter phenomenology of this model. We show that the observed dark matter density can be obtained via gauge or scalar interactions, and that semi-annihilations could play an important role in the latter case. The regions consistent with the dark matter density are determined in each instance and the prospects for detection in future experiments are analyzed. If dark matter annihilations are controlled by the B-L gauge interaction, the mass of the dark matter particle should lie below 5 TeV and its direct detection cross section can be easily probed by XENON1T; if instead they are controlled by scalar interactions, the dark matter mass can be much larger and the detection prospects are less certain. Finally, we show that this scenario can be readily extended to accommodate multiple dark matter particles.
hep-phJCAP(2015)·74 citations
20*
Effects of an H-mu-tau coupling in quarkonium lepton flavor violation decays
David Delepine🇲🇽 · Mauro Napsuciale🇲🇽 · Eduardo Peinado🇲🇽
In this work we study the consistency of a possible non-vanishing coupling $H μτ$ of the order of $3.6 \times 1 0^{- 3}$ as pointed recently by the CMS and ATLAS collaborations, with measured lepton flavor violation processes involving quarkonium. We show that the most promising channel to confirm this excess is to look for the lepton flavor tau decay into a $f_{0}$ and $μ$ where the experimental limit could strongly improved with the new B factories as Belle II.
hep-ph2 citations
21*
Analysis of Two-body Charmed $B$ Meson Decays in Factorization-Assisted Topological-Amplitude Approach
Si-Hong Zhou🇨🇳 · Yan-Bing Wei🇨🇳 · Qin Qin🇨🇳 · Ying Li🇨🇳 · Fu-Sheng Yu🇨🇳 · Cai-Dian Lu🇨🇳
Within the factorization-assisted topological-amplitude approach, we study the two-body charmed $B$ meson decays $B_{u, d, s} \to D^{(*)} M$ , with $M$ denoting a light pseudoscalar (or vector) meson. The meson decay constants and transition form factors are factorized out from the hadronic matrix element of topological diagrams. Therefore the effect of SU(3) symmetry breaking is retained, which is different from the conventional topological diagram approach. The number of free nonperturbative parameters to be fitted from experimental data is also much less. Only four universal nonperturbative parameters $χ^{C}$ , $ϕ^{C}$ , $χ^{E}$ and $ϕ^{E}$ are introduced to describe the contribution of the color suppressed tree and $W$ -exchanged diagrams for all the decay channels. With the fitted parameters from 31 decay modes induced by $b \to c$ transition, we then predict the branching fractions of 120 decay modes induced by both $b \to c$ and $b \to u$ transitions. Our results are well consistent with the measured data or to be tested in the LHCb and Belle-II experiments in the future. Besides, the SU(3) symmetry breaking, isospin violation and $C P$ asymmetry are also investigated.
hep-phhep-exPRD(2015)·58 citations
22*
Two-loop Neutrino Model with Exotic Leptons
Hiroshi Okada🇹🇼 · Yuta Orikasa🇰🇷
We propose a two-loop induced neutrino mass model, in which we show some bench mark points to satisfy the observed neutrino oscillation, the constraints of lepton flavor violations, and the relic density in the co-annihilation system satisfying the current upper bound on the spin independent scattering cross section with nuclei. We also discuss new sources of muon anomalous magnetic moment.
hep-phPRD(2016)·31 citations
23*
Heavy flavor in nucleus-nucleus and proton-nucleus: quenching, flow and correlations
M. Nardi🇮🇹 · A. Beraudo🇮🇹 · A. De Pace🇮🇹 · M. Monteno🇮🇹 · F. Prino (INFN Torino)🇮🇹
We present recent results for heavy-flavor observables in nucleus-nucleus collisions at LHC energies, obtained with the POWLANG transport setup. The initial creation of c-cbar and b-bbar pairs is simulated with a perturbative QCD approach (POWHEG+PYTHIA); their propagation in the medium (created in the nucleus-nucleus or in proton-nucleus collision) is studied with the relativistic Langevin equation, here solved using weak-coupling transport coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor and the elliptic flow parameter of the final D mesons both in nucleus-nucleus and in (for the first time, in the POWLANG setup) proton-nucleus collisions and compare our results to experimental data.
hep-phnucl-thNucl.Part.Phys.Proc.(2016)·7 citations
24*
Checking T and CPT violation with sterile neutrino
Yogita Pant · Sujata Diwakar · Jyotsna Singh🇮🇳 · R.B. Singh🇮🇳
Post LSND results, sterile neutrinos have drawn attention and motivated the high energy physics, astronomy and cosmology to probe physics beyond the standard model considering minimal 3+1 (3 active and 1 sterile) to 3+N neutrino schemes. The analytical equations for neutrino conversion probabilities are developed in this work for 3+1 neutrino scheme. Here, we have tried to explore the possible signals of T and CPT violations with four flavor neutrino scheme at neutrino factory. Values of sterile parameters considered in this analysis are taken from two different types of neutrino experiments viz. long baseline experiments and reactor+atmospheric experiments. In this work golden and discovery channels are selected for the investigation of T violation. While observing T violation we stipulate that neutrino factory working at 50 GeV energy have the potential to observe the T violation signatures for the considered range of baselines(3000 km-7500 km). The ability of neutrino factory for constraining CPT violation is enhanced with increase in energy for normal neutrino mass hierarchy(NH). Neutrino factory with the exposure time of 500 kt-yr will be able to capture CPT violation with $δ c_{31} \geq 3.6 \times 1 0^{- 23}$ GeV at 3 $σ$ level for NH and for IH with $δ c_{31} \geq 4 \times 1 0^{- 23}$ GeV at 3 $σ$ level.
hep-phNPB(2016)·1 citation
25*
Exploring central opacity and asymptotic scenarios in elastic hadron scattering
D. A. Fagundes🇧🇷 · M. J. Menon🇧🇷 · P. V. R. G. Silva🇧🇷
In the absence of a global description of the experimental data on elastic and soft diffractive scattering from the first principles of QCD, model-independent analyses may provide useful phenomenological insights for the development of the theory in the soft sector. With that in mind, we present an empirical study on the energy dependence of the ratio $X$ between the elastic and total cross sections; a quantity related to the evolution of the hadronic central opacity. The dataset comprises all the experimental information available on proton-proton and antiproton-proton scattering in the c.m. energy interval 5 GeV - 8 TeV. Generalizing previous works, we discuss four model-independent analytical parameterizations for $X$ , consisting of sigmoid functions composed with elementary functions of the energy and three distinct asymptotic scenarios: either the standard black disk limit or scenarios above or below that limit. Our two main conclusions are the following: (1) although consistent with the experimental data, the black disk does not represent an unique solution; (2) the data reductions favor a semi-transparent scenario, with asymptotic average value for the ratio $X ˉ$ = 0.30 $\pm$ 0.12. In this case, within the uncertainty, the asymptotic regime may already be reached around 1000 TeV. We present a comparative study of the two scenarios, including predictions for the inelastic channel (diffraction dissociation) and the ratio associated with the total cross-section and the elastic slope. Details on the selection of our empirical ansatz for $X$ and physical aspects related to a change of curvature in this quantity at 80 - 100 GeV, indicating the beginning of a saturation effect, are also presented and discussed.
hep-phhep-exnucl-thNPA(2016)·26 citations
26*
A simple merging algorithm for jet angular correlation studies
Junya Nakamura🇩🇪
A tree level merging algorithm which guarantees the leading order (LO) accuracy of angular correlations between jets is proposed and studied. The algorithm is designed so that n-jet events are generated exclusively according to the LO n-parton production cross section and each of the n-jet is close to each of the n-parton in terms of the jet measure. As a result, the LO accuracy of angular correlations between the n-jet is robust. Furthermore, as long as the n-jet events are exclusively subjects to a study, only the LO n-parton production cross section is needed and hence event generation is efficient. Correlations in the azimuthal angle difference between the two highest transverse momentum jets with large rapidity separations in the top quark pair production are evaluated as examples. The algorithm is validated by discussing numerical differences between its predictions and the predictions of a well-established merging algorithm.
hep-phJHEP(2016)·2 citations
27*
Resolving charm and bottom quark masses in precision Higgs boson analyses
Alexey A. Petrov🇺🇸 · Stefan Pokorski🇵🇱 · James D. Wells🇺🇸 · Zhengkang Zhang🇺🇸
Masses of the charm and bottom quarks are important inputs to precision calculations of Higgs boson observables, such as its partial widths and branching fractions. They constitute a major source of theory uncertainties that needs to be better understood and reduced in light of future high-precision measurements. Conventionally, Higgs boson observables are calculated in terms of $m_{c}$ and $m_{b}$ , whose values are obtained by averaging over many extractions from low-energy data. This approach may ultimately be unsatisfactory, since $m_{c}$ and $m_{b}$ as single numbers hide various sources of uncertainties involved in their extractions some of which call for more careful estimations, and also hide correlations with additional inputs such as $α_{s}$ . Aiming at a more detailed understanding of the uncertainties from $m_{c}$ and $m_{b}$ in precision Higgs boson analyses, we present a calculation of Higgs boson observables in terms of low-energy observables, which reveals concrete sources of uncertainties that challenge sub-percent-level calculations of Higgs boson partial widths.
hep-ph1 citation
28*
Transition form factors $γ^{*} \to γ f_{2} (1270)$ and $γ^{*} \to γ a_{2} (1320)$ in the $e^{+} e^{-}$ collisions
N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺
The predictions for transition form factors $γ^{*} \to γ f_{2} (1270)$ and $γ^{*} \to γ a_{2} (1320)$ and corresponding $e^{+} e^{-} \to γ^{*} \to f_{2} γ$ and $e^{+} e^{-} \to γ^{*} \to a_{2} γ$ cross sections are obtained for the energy region up to $2$ GeV. These predictions are coordinated with the recent Belle data on the $γ^{*} (Q^{2}) γ \to f_{2}$ transition. It is shown that the QCD asymptotics of the amplitudes of the reactions $e^{+} e^{-} \to γ^{*} \to f_{2} γ$ and $e^{+} e^{-} \to γ^{*} \to a_{2} γ$ can be reached only by taking into account a compensation of contributions of $ρ (770)$ , $ω (782)$ with contributions of their radial excitations. The relation $σ (e^{+} e^{-} \to γ^{*} \to f_{2} γ) / σ (e^{+} e^{-} \to γ^{*} \to a_{2} γ) \approx 25/9$ , obtained with the help of the $q q ˉ$ model of $a_{2}$ and $f_{2}$ and QCD, is used to determine the $σ (e^{+} e^{-} \to γ^{*} \to a_{2} γ)$ at high energies. Recent BABAR measurement of the $e^{+} e^{-} \to f_{2} γ \to π^{+} π^{-} γ$ cross section at $10.58$ GeV gives hope for detailed investigation of the $γ^{*} (s) \to f_{2} γ$ and $γ^{*} (s) \to a_{2} γ$ transition form factors at high energy region.
hep-phhep-exnucl-thEPJ Web Conf.(2016)·2 citations
29*
Robust characteristics of nongaussian fluctuations from the NJL model
Jiunn-Wei Chen🇹🇼 · Jian Deng🇨🇳 · Hiroaki Kohyama🇹🇼 · Lance Labun🇺🇸
We evaluate the third- and fourth-order baryon, charge and strangeness susceptibilities near a chiral critical point using the Nambu-Jona-Lasinio model. We identify robust qualitative behaviours of the susceptibilities along hypothetical freeze-out lines that agree with previous model studies. Quantitatively, baryon number fluctuations are the largest in magnitude and thus offer the strongest signal when freeze-out occurs farther away from a critical point. Charge and strangeness susceptibilities also diverge at a critical point, but the area where the divergence dominates is smaller, meaning freeze-out must occur closer to a critical point for a signal to be visible in these observables. In case of strangeness, this is attributable to the relatively large strange quark mass. Plotting the third- and fourth-order susceptibilities against each other along the freeze-out line exhibits clearly their non-montonicity and robust features.
hep-phnucl-exnucl-thPRD(2016)·52 citations
30*
Wilson RG of Noncommutative $Φ_{4}^{4}$
Badis Ydri🇩🇿 · Rachid Ahmim🇩🇿 · Adel Bouchareb🇩🇿
We present a study of phi-four theory on noncommutative spaces using a combination of the Wilson renormalization group recursion formula and the solution to the zero dimensional vector/matrix models at large $N$ . Three fixed points are identified. The matrix model $θ = \infty$ fixed point which describes the disordered-to-non-uniform-ordered transition. The Wilson-Fisher fixed point at $θ = 0$ which describes the disordered-to-uniform-ordered transition, and a noncommutative Wilson-Fisher fixed point at a maximum value of $θ$ which is associated with the transition between non-uniform-order and uniform-order phases.
↳ hep-thhep-phmath-phmath.MPInt.J.Mod.Phys.A(2015)·3 citations
31*
Chiral pumping effect induced by rotating electric fields
Shu Ebihara🇯🇵 · Kenji Fukushima🇯🇵 · Takashi Oka🇩🇪
We propose an experimental setup using 3D Dirac semimetals to access a novel phenomenon induced by the chiral anomaly. We show that the combination of a magnetic field and a circularly polarized laser induces a finite charge density with an accompanying axial current. This is because the circularly polarized laser breaks time-reversal symmetry and the Dirac point splits into two Weyl points, which results in an axial-vector field. We elucidate the appearance of the axial-vector field with the help of the Floquet theory by deriving an effective Hamiltonian for high-frequency electric fields. This anomalous charge density, i.e. the chiral pumping effect, is a phenomenon reminiscent of the chiral magnetic effect with a chiral chemical potential. We explicitly compute the pumped density and the axial-current expectation value. We also take account of coupling to the chiral magnetic effect to calculate a balanced distribution of charge and chirality in a material that behaves as a chiral battery.
↳ cond-mat.str-elhep-phPRB(2016)·54 citations
32*
In-medium heavy-quarkonium from lattice QCD spectral functions
Alexander Rothkopf🇩🇪
We discuss recent progress in the study of in-medium heavy quarkonium using first-principles lattice QCD calculations and effective field theory. In particular our focus lies on real-time information carried by QCD spectral functions and we report on a novel strategy for their extraction from Euclidean-time simulations. Combining an effective description for heavy quarks with finite temperature lattice QCD we compute in-medium spectra providing insight in heavy quarkonium melting in a static thermal medium. On the other hand we use spectral information to extract the complex in-medium potential which provides the basis for a dynamical description of quarkonium real-time evolution via the Schrödinger equation.
↳ hep-lathep-phJ.Phys.Conf.Ser.(2016)·1 citation
33*
Gauged Nambu-Jona-Lasinio inflation
Tomohiro Inagaki🇯🇵 · Sergei D. Odintsov🇪🇸 · Hiroki Sakamoto🇯🇵
We investigate the gauged Nambu-Jona-Lasinio model in curved spacetime at the large $N_{c}$ limit and in slow-roll approximation. The model can be described by the renormalization group corrected gauge-Higgs-Yukawa theory with the corresponding compositeness conditions. Evaluating the renormalization group (RG) improved effective action, we show that such model can produce CMB fluctuations and find inflationary parameters: spectral index, tensor-to-scalar-ratio and running of the spectral index. We demonstrate that the model can naturally satisfy the Planck 2015 data and maybe considered as an alternative candidate for Higgs inflation.
↳ hep-thastro-ph.COgr-qchep-phAstrophys.Space Sci.(2015)·23 citations
34*
Multiverse as an ensemble of stable and unstable Universes
K. Urbanowski🇵🇱
Estimates of the Higgs and top quark masses, $m_{H} ≃ 125.10 \pm 0.14$ [GeV] and $m_{t} ≃ 172.76 \pm 0.30$ [GeV] based on the experimental results place the Standard Model in the region of the metastable vacuum. A consequence of the metastability of the Higgs vacuum is that it should induce the decay of the electroweak vacuum in the early Universe with catastrophic consequences. It may happen that certain universes were lucky enough to survive the time of canonical decay, that is the exponential decay, and live longer. This means that it is reasonable to analyze conditions allowing for that. We analyze properties of an ensemble of Universes with unstable vacua considered as an ensemble of unstable systems from the point of view of the quantum theory of unstable states. We found some symmetry relations for quantities characterizing the metastable state. We also found a relation linking the decay rate, $Γ$ of the metastable vacuum state with the Hubble parameter $H (t)$ , which may help to explain why a universe with an unstable vacuum that lives longer then the canonical decay times need not decay.
↳ gr-qchep-phSymmetry(2023)·3 citations
35*
First-order Cosmological Perturbations Engendered by Point-like Masses
Maxim Eingorn🇺🇸
In the framework of the concordance cosmological model the first-order scalar and vector perturbations of the homogeneous background are derived in the weak gravitational field limit without any supplementary approximations. The sources of these perturbations (inhomogeneities) are presented in the discrete form of a system of separate point-like gravitating masses. The found expressions for the metric corrections are valid at all (sub-horizon and super-horizon) scales and converge at all points except at locations of the sources. The average values of these metric corrections are zero (thus, first-order backreaction effects are absent). Both the Minkowski background limit and the Newtonian cosmological approximation are reached under certain well-defined conditions. An important feature of the velocity-independent part of the scalar perturbation is revealed: up to an additive constant this part represents a sum of Yukawa potentials produced by inhomogeneities with the same finite time-dependent Yukawa interaction range. The suggested connection between this range and the homogeneity scale is briefly discussed along with other possible physical implications.
↳ gr-qcastro-ph.COhep-phhep-thApJ(2016)·58 citations
36*
Double Lambda He-6 in cluster effective field theory
S.-I. Ando (Sunmoon U.)🇰🇷 · Y. Oh (Kyungpook National U.)🇰🇷
The bound state of \nuclide[6][\Lambda\Lambda]{He} is studied as a three-body ( $ΛΛ α$ ) system in a cluster effective field theory at leading order (LO). We find that the system exhibits the limit cycle which is associated with the formation of bound states called the Efimov states. This implies that the three-body contact interaction should be promoted to LO. The relationship of the binding energy and the $ΛΛ$ scattering length is discussed as well as the role of the scale in this system.
↳ nucl-thhep-phEPJ Web Conf.(2016)·0 citations
37*
Quantum Primordial Standard Clocks
Xingang Chen🇺🇸 · Mohammad Hossein Namjoo🇺🇸 · Yi Wang🇨🇳
In this paper, we point out and study a generic type of signals existing in the primordial universe models, which can be used to model-independently distinguish the inflation scenario from alternatives. These signals are generated by massive fields that function as standard clocks. The role of massive fields as standard clocks has been realized in previous works. Although the existence of such massive fields is generic, the previous realizations require sharp features to classically excite the oscillations of the massive clock fields. Here, we point out that the quantum fluctuations of massive fields can actually serve the same purpose as the standard clocks. We show that they are also able to directly record the defining property of the scenario type, namely, the scale factor of the primordial universe as a function of time a(t), but through shape-dependent oscillatory features in non-Gaussianities. Since quantum fluctuating massive fields exist in any realistic primordial universe models, these quantum primordial standard clock signals are present in any inflation models, and should exist quite generally in alternative-to-inflation scenarios as well. However, the amplitude of such signals is very model-dependent.
↳ astro-ph.COhep-phhep-thJCAP(2016)·141 citations
38*
Non-Relativistic Approximation of Dirac Equation for Slow Fermions Coupled to the Chameleon and Torsion Fields in the Gravitational Field of the Earth
A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹
We analyse a non-relativistic approximation of the Dirac equation for slow fermions, coupled to the chameleon field and torsion in the spacetime with the Schwarzschild metric, taken in the weak gravitational field of the Earth approximation. We follow the analysis of the Dirac equation in the curved spacetime with torsion, proposed by Kostelecky (Phys. Rev. D69, 105009 (2004)), and apply the Foldy--Wouthuysen transformations. We derive the effective low-energy gravitational potentials for slow fermions, coupled to the gravitational field of the Earth, the chameleon field and to torsion with minimal and non-minimal couplings.
↳ gr-qcastro-ph.IMhep-phnucl-ex+1PRD(2015)·10 citations
39*
Measurement of the $D^{0} \to π^{-} e^{+} ν$ branching fraction, form factor and implications for $V_{u b}$
Arantza Oyanguren (on behalf of the BaBar collaboration)🇪🇸
In this talk results of the study of the $D^{0} \to π^{-} e^{+} ν$ decay channel, recorded by the BaBar detector at the c.m. energy close to 10.6 GeV, are reported. The branching fraction of this channel is measured relative to the $D^{0} \to K^{-} π^{+}$ decay. The hadronic form factor, $f_{+, D}^{π} (q^{2})$ , function of $q^{2}$ , the four momentum transfer squared between the $D$ and the $π$ mesons, is compared to various theoretical predictions, and the normalization $V_{c d} \times f_{+, D}^{π} (q^{2} = 0)$ is extracted from a fit to data. Results are compared with Lattice QCD calculations. A new multipole model is applied which makes use of present information of resonant states contributing to the form factor. With the understanding of the $f_{+, D}^{π} (q^{2})$ form factor, and provided the relation between the $D^{0} \to π^{-} e^{+} ν$ and $B^{0} \to π^{-} e^{+} ν$ decay widths at the same pion energy, the CKM matrix element $V_{u b}$ is determined and compared to recent measurements. This method of extracting $V_{u b}$ will become competitive with new Lattice QCD calculations of the ratio of form factors.
↳ hep-exhep-ph1 citation
40*
Pentaquarks and Tetraquarks at LHCb
Sheldon Stone🇺🇸
Exotic resonant structures found in $Λ_{b}^{0}$ and $B^{0}$ decays into charmonium in the LHCb experiment are discussed. Examination of the $J / ψ p$ system in $Λ_{b}^{0} \to J / ψ K^{-} p$ decays shows two states each of which must be composed of $uu d c c$ quarks, and thus are called charmonium pentaquarks. Their masses are $4380 \pm 8 \pm 29$ ~MeV and $4449.8 \pm 1.7 \pm 2.5$ ~MeV, and their corresponding widths ( $Γ$ ) are $205 \pm 18 \pm 86$ MeV, and $39 \pm 5 \pm 19$ MeV. The preferred $J^{P}$ assignments are of opposite parity, with one state having spin 3/2 and the other 5/2. Models of internal binding of the pentaquark states are discussed. Finally, another mesonic state is discussed, the $Z (4430)^{-}$ that decays into $ψ^{'} π^{-}$ and was first observed by the Belle collaboration in $B^{0} \to ψ^{'} K^{+} π^{-}$ decays. Using a sample of approximately 25,000 signal events, LHCb determines the $J^{P}$ to be $1^{+}$ .
↳ hep-exhep-phnucl-exnucl-thPoS(2015)·13 citations
41*
Electromagnetic fields and anomalous transports in heavy-ion collisions --- A pedagogical review
Xu-Guang Huang🇨🇳
The hot and dense matter generated in heavy-ion collisions may contain domains which are not invariant under P and CP transformations. Moreover, heavy-ion collisions can generate extremely strong magnetic fields as well as electric fields. The interplay between the electromagnetic field and triangle anomaly leads to a number of macroscopic quantum phenomena in these P- and CP-odd domains known as the anomalous transports. The purpose of the article is to give a pedagogical review of various properties of the electromagnetic fields, the anomalous transports phenomena, and their experimental signatures in heavy-ion collisions.
↳ nucl-thhep-phnucl-exRept.Prog.Phys.(2016)·359 citations
42*
Finite Volume and Partially Quenched QCD-like Effective Field Theories
Johan Bijnens🇸🇪 · Thomas Rössler (Lund)🇸🇪
We present a calculation of the meson masses, decay constants and quark-antiquark vacuum expectation value for the three generic QCD-like chiral symmetry breaking patterns $S U (N_{F}) \times S U (N_{F}) \to S U (N_{F})_{V}$ , $S U (N_{F}) \to S O (N_{F})$ and $S U (2 N_{F}) \to S p (2 N_{F})$ in the effective field theory for these cases. We extend the previous two-loop work to include effects of partial quenching and finite volume. The calculation has been performed using the quark flow technique. We reproduce the known infinite volume results in the unquenched case. The analytical results can be found in the supplementary material. Some examples of numerical results are given. The numerical programs for all cases are included in version 0.54 of the CHIRON package. The purpose of this work is the use in lattice extrapolations to zero mass for QCD-like and strongly interacting Higgs sector lattice calculations.
↳ hep-lathep-phJHEP(2015)·4 citations
43*
Reduction of the $K^{*}$ meson abundance in heavy ion collisions
Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷
We study the $K^{*}$ meson reduction in heavy ion collisions by focusing on the hadronic effects on the $K^{*}$ meson abundance. We evaluate the absorption cross sections of the $K^{*}$ and $K$ meson by light mesons in the hadronic matter, and further investigate the variation in the meson abundances for both particles during the hadronic stage of heavy ion collisions. We show how the interplay between the interaction of the $K^{*}$ meson and kaon with light mesons in the hadronic medium determines the final yield difference of the statistical hadronization model to the experimental measurements. For the central Au+Au collision at $s_{N N} = 200$ GeV, we find that the $K^{*} / K$ yield ratio at chemical freeze-out decreases by $36%$ during the expansion of the hadronic matter, resulting in the final ratio comparable to STAR measurements of 0.23 $\pm 0.05$ .
↳ nucl-thhep-phnucl-exPRC(2018)·27 citations
44*
Pseudorapidity correlations in heavy ion collisions from viscous fluid dynamics
Akihiko Monnai🇺🇸 · Bjoern Schenke🇺🇸
We demonstrate by explicit calculations in 3+1 dimensional viscous relativistic fluid dynamics how two-particle pseudorapidity correlation functions in heavy ion collisions at the LHC and RHIC depend on the number of particle producing sources and the transport properties of the produced medium. In particular, we present results for the Legendre coefficients of the two-particle pseudorapidity correlation function in Pb+Pb collisions at 2760 GeV and Au+Au collisions at 200 GeV from viscous hydrodynamics with three dimensionally fluctuating initial conditions. Our results suggest that these coefficients provide important constraints on initial state fluctuations and the transport properties of the quark gluon plasma.
↳ nucl-thhep-phnucl-exPLB(2016)·43 citations
45*
Two-particle correlations in pseudorapidity in a hydrodynamic model
Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱 · Adam Olszewski🇵🇱
Two-particle pseudorapidity correlations of hadrons produced in Pb+Pb collisions at 2.76 TeV at the CERN Large Hadron Collider are analyzed in the framework of a model based on viscous 3+1-dimensional hydrodynamics with the Glauber initial condition. Based on our results, we argue that the correlation from resonance decays, formed at a late stage of the evolution, produce significant effects. In particular, their contribution to the event averages of the coefficients of the expansion in the Legendre basis explain 60-70% of the experimental values. We have proposed an accurate way to compute these <a_n a_m> coefficients, independent of the binning in pseudorapidity, and tested a double expansion of the two-particle correlation function in the azimuth and pseudorapidity, which allows us to investigate the pseudorapidity correlations between harmonics of the collective flow. In our model, these quantities are also dominated by non-flow effects from the resonance decays. Finally, our method can be used to compute higher-order cumulants for the expansion in orthonormal polynomials which offers a suitable way of eliminating the non-flow effects from the correlation analyses.
↳ nucl-thhep-phnucl-exPRC(2015)·21 citations
46*
Scalar perturbations in the late Universe: viability of the Chaplygin gas models
Mariam Bouhmadi-López🇵🇹 · Maxim Brilenkov🇺🇦 · Ruslan Brilenkov🇺🇦 · João Morais🇪🇸 · Alexander Zhuk🇺🇦
We study the late-time evolution of the Universe where dark energy (DE) is parametrized by a modified generalized Chaplygin gas (mGCG) on top of cold dark matter (CDM). We also take into account the radiation content of the Universe. In this context, the late stage of the evolution of the universe refers to the epoch where CDM is already clustered into inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies). Under these conditions, the mechanical approach is an adequate tool to study the Universe deep inside the cell of uniformity. To be more accurate, we study scalar perturbations of the Friedmann-Lemaître-Robertson-Walker metric due to inhomogeneities of CDM as well as fluctuations of radiation and mGCG, the later driving the late-time acceleration of the universe. Our analysis applies as well to the case where mGCG plays the role of DM and DE. We select the sets of parameters of the mGCG that are compatible with the mechanical approach. These sets define prospective mGCG models. By comparing the selected sets of models with some of the latest observational data results, we conclude that the mGCG is in tight agreement with those observations particularly for a mGCG playing the role of DE and DM.
↳ gr-qcastro-ph.COhep-phhep-thJCAP(2015)·17 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.