HEP Phenomenology·hep-ph

Thu·Nov 16, 2017Thursday·November 16, 2017

34 papers—25 primary·9 cross-listed·reconstructed*

01*
The fate of small classically stable Q-balls
Dmitry Levkov🇷🇺 · Emin Nugaev🇷🇺 · Andrei Popescu🇷🇺
The smallest classically stable Q-balls are, in fact, generically metastable: in quantum theory they decay into free particles via collective tunneling. We derive general semiclassical method to calculate the rate of this process in the entire kinematical region of Q-ball metastability. Our method uses Euclidean field-theoretical solutions resembling the Coleman's bounce and fluctuations around them. As an application of the method, we numerically compute the decay rate to the leading semiclassical order in a particular one-field model. We shortly discuss cosmological implications of metastable Q-balls.
hep-phastro-ph.COhep-thJHEP(2017)·27 citations
02*
Dark matter-neutrino interactions through the lens of their cosmological implications
Andres Olivares-Del Campo (1)🇬🇧 · Celine Boehm (1, 2, 3)🇬🇧 · Sergio Palomares-Ruiz (4)🇪🇸 · Silvia Pascoli (1) ((1) Durham U., IPPP, (2) Annecy, LAPTH, (3) Perimeter Inst. Theor. Phys., (4) Valencia U., IFIC)🇬🇧
Dark matter and neutrinos provide the two most compelling pieces of evidence for new physics beyond the Standard Model of Particle Physics but they are often treated as two different sectors. The aim of this paper is to determine whether there are viable particle physics frameworks in which dark matter can be coupled to active neutrinos. We use a simplified model approach to determine all possible renormalizable scenarios where there is such a coupling, and study their astrophysical and cosmological signatures. We find that dark matter-neutrino interactions have an impact on structure formation and lead to indirect detection signatures when the coupling between dark matter and neutrinos is sufficiently large. This can be used to exclude a large fraction of the parameter space. In most cases, dark matter masses up to a few MeV and mediator masses up to a few GeV are ruled out. The exclusion region can be further extended when dark matter is coupled to a spin-1 mediator or when the dark matter particle and the mediator are degenerate in mass if the mediator is a spin-0 or spin-1/2 particle.
hep-phPRD(2018)·143 citations
03*
CP tests of Higgs couplings in $t t ˉ h$ semileptonic events at the LHC
D. Azevedo🇵🇹 · A. Onofre🇵🇹 · F. Filthaut🇳🇱 · R. Gonçalo🇵🇹
The CP nature of the Higgs coupling to top quarks is addressed in this paper, in single charged lepton final states of $t t ˉ h$ events produced in proton-proton collisions at the LHC. Pure scalar ( $h = H$ ) and pseudo-scalar ( $h = A$ ) Higgs boson signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed using a kinematic fit. Angular distributions of the decay products, as well as CP-sensitive asymmetries, are exploited to separate and gain sensitivity to possible pseudo-scalar components of the Higgs boson and reduce the contribution from the dominant irreducible background $t t ˉ b b ˉ$ . Significant differences are found between the pure CP-even and -odd signal hypotheses as well as with respect to the Standard Model background, in particular the $t t ˉ b b ˉ$ contribution. Such differences survive the event reconstruction, allowing to define optimal observables to extract the Higgs couplings parameters from a global fit. A dedicated analysis is applied to efficiently identify signal events and reject as much as possible the expected Standard Model background. The results obtained are compared with a similar analysis in the dilepton channel. We show that the single lepton channel is more promising overall and can be used in combination to study the CP nature of the Higgs coupling to top quarks.
hep-phPRD(2018)·47 citations
04*
Testing the Scalar Sector of the Twin Higgs Model at Colliders
Zackaria Chacko🇺🇸 · Can Kilic🇺🇸 · Saereh Najjari🇵🇱 · Christopher B. Verhaaren🇺🇸
We consider Mirror Twin Higgs models in which the breaking of the global symmetry is realized linearly. In this scenario, the radial mode in the Higgs potential is present in the spectrum, and constitutes a second portal between the twin and SM sectors. We show that a study of the properties of this particle at colliders, when combined with precision measurements of the light Higgs, can be used to overdetermine the form of the scalar potential, thereby confirming that it possesses an enhanced global symmetry as dictated by the Twin Higgs mechanism. We find that, although the reach of the LHC for this state is limited, future linear colliders will be able to explore a significant part of the preferred parameter space, allowing the possibility of directly testing the Twin Higgs framework.
hep-phhep-exPRD(2018)·37 citations
05*
Radiative lepton flavor violating B, D, and K decays
Derek E. Hazard🇺🇸 · Alexey A. Petrov🇺🇸
We argue that radiative lepton flavor violating (RLFV) decays $P \to γ ℓ_{1} ℓ_{2}$ of $P = B_{q}^{0}$ , $D ˉ^{0}$ , and $K^{0}$ meson states are robust probes of new physics models. In particular, they could be used to put constraints on the Wilson coefficients of effective operators describing lepton flavor-changing neutral current interactions at low energy scales. We set up a generic framework for describing these transitions and review new physics constraints from $P \to ℓ_{1} ℓ ˉ_{2}$ decays. There is discussion of how RLFV transitions provide access to the operators that cannot be constrained in two-body decays and we in turn motivate further experimental searches via these channels.
hep-phhep-exPRD(2018)·21 citations
06*
The Supersymmetric Georgi-Machacek Model
Roberto Vega🇺🇸 · Roberto Vega-Morales🇪🇸 · Keping Xie🇺🇸
We show that the well known Georgi-Machacek (GM) model can be realized as a limit of the recently constructed Supersymmetric Custodial Higgs Triplet Model (SCTM) which in general contains a significantly more complex scalar spectrum. We dub this limit of the SCTM, which gives a weakly coupled origin for the GM model at the electroweak scale, the Supersymmetric GM (SGM) model. We derive a mapping between the SGM and GM models using it to show how a supersymmetric origin implies constraints on the Higgs potential in conventional GM model constructions which would generically not be present. We then perform a simplified phenomenological study of diphoton and ZZ signals for a pair of benchmark scenarios to illustrate under what circumstances the GM model can mimic the SGM model and when they should be easily distinguishable.
hep-phhep-exJHEP(2018)·13 citations
07*
Extended MSSM in Supersymmetric $SO (10)$ Grand Unification
Sibo Zheng🇨🇳
We apply the perturbative grand unification due to renormalization to distinguish TeV-scale relics of supersymmetric $SO (10)$ scenarios. With rational theoretical constraints taken into account, we find that for the breaking pattern of either $SU (5)$ or Pati-Salam only extra matter $16$ supermultiplet of $S O (10)$ can appear at TeV scale, apart from MSSM spectrum.
hep-phPRD(2018)·4 citations
08*
Clockwork Mechanism for Flavour Hierarchies
Ketan M. Patel🇮🇳
We incorporate clockwork mechanism into the Standard Model flavour sector and show that the observed pattern of fermion masses and mixing can be obtained without any unnaturally small or large parameter in the fundamental theory. By introducing $N_{f}$ pairs of vectorlike fermions, as clockwork gears, for each generation of the Standard Model fermions and setting up a characteristic clockwork potential, it is shown that the inter-generational mass hierarchies are determined by $N_{f}$ . For a given type of fermions, strong or mild hierarchy in the masses and mixing parameters can be obtained by taking the large or small value of $N_{f}$ . The mechanism is shown to lead to a generalized version of the Froggatt-Nielsen mechanism as an effective description.
hep-phPRD(2017)·31 citations
09*
Indirect Probe of Electroweakly Interacting Particles at the High-Luminosity Large Hadron Collider
Shigeki Matsumoto🇯🇵 · Satoshi Shirai🇯🇵 · Michihisa Takeuchi🇯🇵
Many extensions of the standard model (SM) involve new massive particles charged under the electroweak gauge symmetry. The electroweakly interacting new particles affect various SM processes through radiative corrections. We discuss the possibility of detecting such new particles based on the precise measurement of the SM processes at high energy hadron colliders. It then turns out that Drell-Yan processes receive radiative corrections from the electroweakly interacting particles at the level of $O$ (0.1-10) %. It is hence possible to indirectly search for the Higgsino up to the mass of 400 GeV and the quintet (5-plet) Majorana fermion up to the mass of 1200 GeV at the high-luminosity running of the Large Hadron Collider, if the systematic uncertainty associated with the estimation of the SM background becomes lower than the statistical one.
hep-phhep-exJHEP(2018)·24 citations
10*
Anisotropy of thermal dileptons
V.V. Goloviznin🇷🇺 · A.M. Snigirev🇷🇺 · G.M. Zinovjev🇺🇦
The meaningful specific anisotropy in the angle distribution of leptons with respect to the three-momentum of pair is predicted as a feasibility signature of synchrotron-like mechanism resulting from the quarks interacting with a collective confining color field in the heavy ion collisions. The lepton pair production rate and the spectrum of pair invariant mass are presented for this new dilepton source that is apparently not taken into consideration in the available phenomenological estimates.
hep-phnucl-exnucl-th1 citation
11*
Threshold effects in hadron spectrum: a new spectroscopy?
Pablo G. Ortega🇪🇸 · Jorge Segovia🇪🇸 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸
The exploration of energies above the open-flavor threshold in the meson spectra has led to the appearance of unexpected states difficult to accommodate in the naive picture of a bound state of a quark and an antiquark. Many of such states are located close to meson-meson thresholds, which suggests that molecular structures may be a relevant component in the total wave function of such resonances. In this work, the state of meson-meson molecules calculations is reviewed, using a non-relativistic constituent quark model that has been applied to a wide range of hadronic observables, and therefore all model parameters are completely constrained. The model has been able to reproduce, among others, the properties of the X(3872), described as a mixture of $c c ˉ$ and $D D ˉ^{*}$ states, or the spectrum of the P-wave charm-strange mesons, which are well reproduced only if $D K$ and $D^{*} K$ structures are taken into account. We show that such constituent quark model, which is able to describe the ordinary heavy meson spectra, is also capable of providing a good description of many new states recently reported.
hep-phEPJ Web Conf.(2018)·2 citations
12*
Scalar one-loop vertex integrals as meromorphic functions of space-time dimension d
Johannes Bluemlein (1)🇩🇪 · Khiem Hong Phan (1,2)🇻🇳 · Tord Riemann (1,3) ((1) DESY, (2) Vietnam National University, (3) University of Silesia)🇵🇱
Representations are derived for the basic scalar one-loop vertex Feynman integrals as meromorphic functions of the space-time dimension $d$ in terms of (generalized) hypergeometric functions $_{2} F_{1}$ and $F_{1}$ . Values at asymptotic or exceptional kinematic points as well as expansions around the singular points at $d = 4 + 2 n$ , $n$ non-negative integers, may be derived from the representations easily. The Feynman integrals studied here may be used as building blocks for the calculation of one-loop and higher-loop scalar and tensor amplitudes. From the recursion relation presented, higher n-point functions may be obtained in a straightforward manner.
hep-phActa Phys.Polon.B(2017)·17 citations
13*
Net-baryon number fluctuations in the Hybrid Quark-Meson-Nucleon model at finite density
Michał Marczenko🇵🇱 · Chihiro Sasaki🇵🇱
We study the mean-field thermodynamics and the characteristics of the net-baryon number fluctuations at the phase boundaries for the chiral and deconfinement transitions in the Hybrid Quark-Meson-Nucleon model. The chiral dynamics is described in the linear sigma model, whereas the quark confinement is manipulated by a medium-dependent modification of the particle distribution functions, where an additional scalar field is introduced. At low temperature and finite baryon density, the model predicts a first-, second-order chiral phase transition, or a crossover, depending on the expectation value of the scalar field, and a first-order deconfinement phase transition. We focus on the influence of the confinement over higher-order cumulants of the net-baryon number density. We find that whereas the cumulants show a substantial enhancement around the chiral phase transition, they are not as sensitive to the deconfinement transition.
hep-phnucl-thPRD(2018)·39 citations
14*
Fuchsia and Master Integrals for Energy-Energy Correlations at NLO in QCD
O. Gituliar🇩🇪 · S. Moch🇩🇪
In this talk we discuss some aspects of the analytical calculation of energy correlations in electron-positron annihilation at a next-to-leading order in QCD. Our primary focus is on the most difficult task: the calculation of master integrals for real-emission contributions, which are functions of two dimensionless variables and the dimensional regulator. We use a method of differential equations and their so-called epsilon-form which is constructed with the help of the Fuchsia program based on Lee's algorithm.
hep-phActa Phys.Polon.B(2017)·12 citations
15*
CP violations in a predictive $A_{4}$ symmetry model
T.Phong Nguyen🇻🇳 · L. T. Hue🇻🇳 · D. T. Si🇻🇳 · T. T. Thuc🇻🇳
We will investigate numerically a seesaw model with $A_{4}$ flavor symmetry to find allowed regions satisfying the current experimental neutrino oscillation data, then use them to predict physical consequences. Namely, the lightest active neutrino mass has order of $O (1 0^{- 2})$ eV. The effective neutrino mass $∣ ⟨ m ⟩ ∣$ associated with neutrinoless double beta decay is in the range of $[0.002 eV, 0.038 eV]$ and $[0.048 eV, 0.058 eV]$ corresponding to the normal and the inverted hierarchy schemes. Other relations among relevant physical quantities are shown, so that they can be determined if some of them are confirmed experimentally. The recent data of the baryon asymmetry of the Universe ( $η_{B}$ ) can be explained via leptogenesis caused by the effect of the renormalization group evolution on the Dirac Yukawa couplings, provided the right handed neutrino mass scale $M_{0}$ is ranging from $O (1 0^{8})$ GeV to $O (1 0^{12})$ GeV for $tan β = 3$ . This allowed $M_{0}$ range distinguishes with the scale of $O (1 0^{13})$ GeV concerned by other effects that also generate the consistent $η_{B}$ from leptogenesis. The branching ratio of the decay $μ \to e γ$ may reach the future experimental sensitivity in the very light values of $M_{0}$ . Hence, it will be inconsistent with the $M_{0}$ range predicted from the $η_{B}$ data whenever this decay is detected experimentally.
hep-phPTEP(2020)·9 citations
16*
Higgs Decay, Z Decay and the QCD Beta-Function
P.A. Baikov🇷🇺 · K.G. Chetyrkin🇩🇪 · J.H. Kühn🇩🇪
Recent developments in perturbative QCD, leading to the beta function in five-loop approximation are presented. In a first step the two most important decay modes of the Higgs boson are discussed: decays into a pair of gluons and, alternatively, decays into a bottom-antibottom quark pair. Subsequently the quark mass anomalous dimension is presented which is important for predicting the value of the bottom quark mass at high scales and, consequently, the Higgs boson decay rate into pair of massive quarks, in particular into $b b ˉ$ . In the next section the $α_{s}^{4}$ corrections to the vector- and axial-vector correlator are discussed. These are the essential ingredients for the evaluation of the QCD corrections to the cross section for electron-positron annihilation into hadrons at low and at high energies, to the hadronic decay rate of the $τ$ lepton and for the $Z$ -boson decay rate into hadrons. Finally we present the prediction for the QCD beta-function in five-loop approximation, discuss the analytic structure of the result and compare with experiment at low and at high energies.
hep-phActa Phys.Polon.B(2017)·5 citations
17*
Probing anomalous $W W γ$ Triple Gauge Bosons Coupling at LHeC
Ruibo Li🇨🇳 · Xiao-Min Shen🇨🇳 · Kai Wang🇨🇳 · Tao Xu🇨🇳 · Liangliang Zhang🇨🇳 · Guohuai Zhu🇨🇳
The precision measurement of the $W W γ$ vertex at the future Large Hadron electron Collider (LHeC) at CERN is discussed in this paper. We propose to measure this vertex in the $e^{-} p \to e^{-} W^{\pm} j$ channel as a complement to the conventional charged current $ν_{e} γ j$ channel. In addition to the cross section measurement, $χ^{2}$ method studies of angular variables provide powerful tools to probe the anomalous structure of triple gauge boson couplings. We study the distribution of the well-known azimuthal angle between the final state forward electron and jet in this vector-boson fusion (VBF) process. On the other hand, full reconstruction of leptonic $W$ decay opens a new opportunity to measure $W$ polarization that is also sensitive to the anomalous triple gauge boson couplings. Taking into consideration the superior determination of parton distribution functions~(PDFs) based on future LHeC data, the constraints of $λ_{γ}$ and $Δ κ_{γ}$ might reach up to $O (1 0^{- 3})$ level in the most ideal case with the 2--3~ab $^{- 1}$ data set, which shows a potential advantage compared to those from LHC and LEP data.
hep-phPRD(2018)·23 citations
18*
Exploring triplet-quadruplet fermionic dark matter at the LHC and future colliders
Jin-Wei Wang🇨🇳 · Xiao-Jun Bi🇨🇳 · Qian-Fei Xiang🇨🇳 · Peng-Fei Yin🇨🇳 · Zhao-Huan Yu🇦🇺
We study the signatures of the triplet-quadruplet dark matter model at the LHC and future colliders, including the 100 TeV Super Proton-Proton Collider and the 240 GeV Circular Electron Positron Collider. The dark sector in this model contains one fermionic electroweak triplet and two fermionic quadruplets, which have two kinds of Yukawa couplings to the Higgs doublet. Electroweak production signals of the dark sector fermions in the $monojet + / E_{T}$ , disappearing track, and $multilepton + / E_{T}$ channels at the LHC and the Super Proton-Proton Collider are investigated. Moreover, we study the loop effects of this model on the Circular Electron Positron Collider precision measurements of $e^{+} e^{-} \to Z h$ and $h \to γ γ$ . We find that most of the parameter regions allowed by the observed dark matter relic density will be well explored by such direct and indirect searches at future colliders.
hep-phPRD(2018)·22 citations
19*
Charmonia production from $b$ -hadron decays at LHC with $k_{T}$ -factorization: $J / ψ$ , $ψ (2 S)$ and $J / ψ + Z$
A.V. Lipatov🇷🇺 · S.P. Baranov🇷🇺 · H. Jung🇩🇪 · M.A. Malyshev🇷🇺
We consider the production of $J / ψ$ and $ψ (2 S)$ mesons originating from the decays of $b$ -flavored hadrons at the LHC using the $k_{T}$ -factorization approach. Our analysis covers both inclusive charmonia production and production of $J / ψ$ mesons in association with $Z$ bosons. We apply the transverse momentum dependent (or unintegrated) gluon density in a proton derived from Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation and adopt fragmentation functions based on the non-relativistic QCD factorization to describe the inclusive $b$ -hadron decays into the different charmonium states. Our predictions agree well with latest experimental data taken by the CMS, ATLAS and LHCb Collaborations at $s = 7$ , $8$ and $13$ ~TeV. The contributions from double parton scattering to the associated non-prompt $J / ψ + Z$ production are estimated and found to be small.
hep-phEPJC(2018)·12 citations
20*
Effective alignments as building blocks of flavour models
Ivo de Medeiros Varzielas🇵🇹 · Thomas Neder🇪🇸 · Ye-Ling Zhou🇬🇧
Flavour models typically rely on flavons - scalars that break the family symmetry by acquiring vacuum expectation values in specific directions. We develop the idea of effective alignments, i.e.\ cases where the contractions of multiple flavons give rise to directions that are hard or impossible to obtain directly by breaking the family symmetry. Focusing on the example where the symmetry is $S_{4}$ , we list the effective alignments that can be obtained from flavons vacuum expectation values that arise naturally from $S_{4}$ . Using those effective alignments as building blocks, it is possible to construct flavour models, for example by using the effective alignments in constrained sequential dominance models. We illustrate how to obtain several of the mixing schemes in the literature, and explicitly construct renormalizable models for three viable cases, two of which lead to trimaximal mixing scenarios.
hep-phPRD(2018)·12 citations
21*
GUT monopoles, the Witten effect and QCD axion phenomenology
Nick Houston🇨🇳 · Tianjun Li🇨🇳
Taken individually, magnetic monopoles and axions are both well-motivated aspects of physics beyond the Standard Model. We demonstrate that by virtue of the Witten effect, their interplay is furthermore nontrivial; monopoles break the corresponding axial symmetries explicitly and result in an axion potential lacking the usual instanton-derived exponential suppression factor. As axions are distinguished by their extremely weak interactions, any regime where their effects are enhanced may be of interest. As an application of these findings, we demonstrate that a phenomenologically acceptable population of grand-unification monopoles in the early Universe can efficiently suppress both the QCD axion dark matter abundance and CMB isocurvature contribution.
hep-phastro-ph.COhep-th3 citations
22*
Signal for a light singlet scalar at the LHC
We-Fu Chang🇹🇼 · Tanmoy Modak🇹🇼 · John N. Ng🇨🇦
In the general Higgs portal like models, the extra neutral scalar, $S$ , can mix with the Standard Model (SM) Higgs boson, $H$ . We perform an exploratory study focusing on the direct search for such a light singlet $S$ at the Large Hadron Collider (LHC). After careful study of the SM background, we find the process $pp \to t t ˉ S$ followed by $S \to b b ˉ$ can be used to investigate $S$ with mass in the $20 < M_{S} < 100$ GeV range, which has not been well explored at the LHC. The signal significance becomes meaningful with a luminosity around a few $\mbox ab^{- 1}$ . Also, we study the prospects of finding the light scalar at the future 100 TeV $pp$ collider, the $Z$ and Higgs factories. With similar luminosity, the current LEP limits on the mixing between $S$ and $H$ can be improved by at least one or two orders of magnitude.
hep-phPRD(2018)·31 citations
23*
Accidental Peccei-Quinn Symmetry from Discrete Flavour Symmetry and Pati-Salam
Fredrik Björkeroth🇮🇹 · Eung Jin Chun🇰🇷 · Stephen F. King🇬🇧
We show how an accidental $U (1)$ Peccei-Quinn (PQ) symmetry can arise from a discrete $A_{4}$ family symmetry combined with a discrete flavour symmetry $Z_{3} \times Z_{5}^{2}$ , in a realistic Pati-Salam unified theory of flavour. Imposing only these discrete flavour symmetries, the axion solution to the strong $C P$ problem is protected from PQ-breaking operators to the required degree. A QCD axion arises from a linear combination of $A_{4}$ triplet flavons, which are also responsible for fermion flavour structures due to their vacuum alignments. We find that the requirement of an accidental PQ symmetry arising from a discrete flavour symmetry constrains the form of the Yukawa matrices, providing a link between flavour and the strong $C P$ problem. Our model predicts specific flavour-violating couplings of the flavourful axion and thus puts a strong limit on the axion scale from kaon decays.
hep-phPLB(2018)·44 citations
24*
Corrections to di-Higgs boson production with light stops and modified Higgs couplings
Peisi Huang🇺🇸 · Aniket Joglekar🇺🇸 · Min Li🇺🇸 · Carlos E. M. Wagner🇺🇸
The Higgs pair production in gluon fusion is a sensitive probe of beyond-Standard Model (BSM) phenomena and its detection is a major goal for the LHC and higher energy hadron collider experiments. In this work we reanalyze the possible modifications of the Higgs pair production cross section within low energy supersymmetry models. We show that the supersymmetric contributions to the Higgs pair production cross section are strongly correlated with the ones of the single Higgs production in the gluon fusion channel. Motivated by the analysis of ATLAS and CMS Higgs production data, we show that the scalar superpartners' contributions may lead to significant modification of the di-Higgs production rate and invariant mass distribution with respect to the SM predictions. We also analyze the combined effects on the di-Higgs production rate of a modification of the Higgs trilinear and top-quark Yukawa couplings in the presence of light stops. In particular, we show that due to the destructive interference of the triangle and box amplitude contributions to the di-Higgs production cross section, even a small modification of the top-quark Yukawa coupling can lead to a significant increase of the di-Higgs production rate.
hep-phPRD(2018)·32 citations
25*
Symmetry breaking, and the effect of matter density on neutrino oscillation
H. Mohseni Sadjadi🇮🇷 · A. P. Khosravi Karchi🇮🇷
A proposal for the neutrino mass, based on neutrino-scalar field interaction, is introduced. The scalar field is also non-minimally coupled to the Ricci scalar and hence relates the neutrino mass to the matter density. In a dense region, the scalar field obeys the $Z_{2}$ symmetry, and the neutrino is massless. In a dilute region, the $Z_{2}$ symmetry breaks and neutrino acquires mass from the non-vanishing expectation value of the scalar field. We consider this scenario in the framework of a spherical dense object whose outside is a dilute region. In this background, we study the neutrino flavors oscillation, along with the consequences of the theory on oscillation length and MSW effect. This preliminary model may shed some lights on the existing anomalies within the neutrino data, concerning the different oscillating behavior of the neutrinos in regions with different densities.
hep-phgr-qchep-thJCAP(2018)·12 citations
26*
Vanishing of local non-Gaussianity in canonical single field inflation
Rafael Bravo🇨🇱 · Sander Mooij🇨🇭 · Gonzalo A. Palma🇨🇱 · Bastián Pradenas🇨🇱
We study the production of observable primordial local non-Gaussianity in two opposite regimes of canonical single field inflation: attractor (standard single field slow-roll inflation) and non attractor (ultra slow-roll inflation). In the attractor regime, the standard derivation of the bispectrum's squeezed limit using co-moving coordinates gives the well known Maldacena's consistency relation $f_{N L} = 5 (1 - n_{s}) /12$ . On the other hand, in the non-attractor regime, the squeezed limit offers a substantial violation of this relation given by $f_{N L} = 5/2$ . In this work we argue that, independently of whether inflation is attractor or non-attractor, the size of the observable primordial local non-Gaussianity is predicted to be $f_{N L}^{o b s} = 0$ (a result that was already understood to hold in the case of attractor models). To show this, we follow the use of the so-called Conformal Fermi Coordinates (CFC), recently introduced in the literature. These coordinates parametrize the local environment of inertial observers in a perturbed FRW spacetime, allowing one to identify and compute gauge invariant quantities, such as $n$ -point correlation functions. Concretely, we find that during inflation, after all the modes have exited the horizon, the squeezed limit of the 3-point correlation function of curvature perturbations vanishes in the CFC frame, regardless of the inflationary regime. We argue that such a cancellation should persist after inflation ends.
↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·40 citations
27*
The equilibrium and dynamical cumulants of QCD chiral order parameter with parametric Landau free energy
Lijia Jiang🇨🇳 · Horst Stoecker🇩🇪 · Jun-Hui Zheng🇨🇳
By linearly parameterizing the QCD Landau free energy near the critical point in the baryon chemical potential and temperature plane, we study the fluctuations of the QCD chiral order parameter field (the $σ$ field) in the equilibrium case and dynamical phase transition, respectively. By setting the system size to the typical size of the QGP fireball ( $\approx 1 0^{3}$ fm $^{3}$ ), we show that in the equilibrium case, the discontinuity of the order parameter in the first order phase transition region is replaced by smooth crossover, and the corresponding fluctuations are broadened. Meanwhile, the quartic cumulant $κ_{4}$ of the $σ$ field is generally negative near the phase transition line. We further derive the dynamical evolution of the QCD Landau free energy in the Fokker-Plank framework, based on which we deduce the dynamical cumulants of the $σ$ field. Assuming the temperature decreases as a known function of time, we numerically evaluate the dynamical cumulants and confirm that the cumulants present clear memory effects. Moreover, the memory effects on the first order phase transition side is stronger than that on the crossover side, and the dynamical cumulants at the hypothetical freeze-out line present rich non-monotonic structures.
↳ nucl-thhep-phEPJC(2023)·8 citations
28*
Structure of the Nucleon and its Excitations
Waseem Kamleh🇦🇺 · Derek Leinweber🇦🇺 · Zhan-wei Liu🇨🇳 · Finn Stokes🇦🇺 · Anthony Thomas🇦🇺 · Samuel Thomas🇦🇺 · Jia-jun Wu🇦🇺
The structure of the ground state nucleon and its finite-volume excitations are examined from three different perspectives. Using new techniques to extract the relativistic components of the nucleon wave function, the node structure of both the upper and lower components of the nucleon wave function are illustrated. A non-trivial role for gluonic components is manifest. In the second approach, the parity-expanded variational analysis (PEVA) technique is utilised to isolate states at finite momenta, enabling a novel examination of the electric and magnetic form factors of nucleon excitations. Here the magnetic form factors of low-lying odd-parity nucleons are particularly interesting. Finally, the structure of the nucleon spectrum is examined in a Hamiltonian effective field theory analysis incorporating recent lattice-QCD determinations of low-lying two-particle scattering-state energies in the finite volume. The Roper resonance of Nature is observed to originate from multi-particle coupled-channel interactions while the first radial excitation of the nucleon sits much higher at approximately 1.9 GeV.
↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·5 citations
29*
Search for rare and exotic Higgs Boson decay modes
Junquan Tao (on behalf of the CMS collaboration)🇨🇳
The latest results in the search for rare and exotic Higgs boson decays in proton-proton collision events collected with the CMS detector at the LHC are presented. The searches are performed for several decay modes of Higgs boson including $H \to X (X \to 2 ℓ) γ$ ( $X = Z, γ^{*}$ and $ℓ = e, μ$ ), $H \to μμ / e e$ , invisible decays, lepton flavour violating decays and Higgs decay to light scalars or pseudo-scalars. No hint for new physics has been found from the analyzed results with the full LHC run-1 data collected during 2011 and 2012 at $s = 7 - 8$ TeV and with the run-2 data at $s = 13$ TeV collected during 2015 and 2016. Limits are set for all the searches which have been performed by CMS.
↳ hep-exhep-phEPJ Web Conf.(2018)·1 citation
30*
Recent progress in applying lattice QCD to kaon physics
Xu Feng🇨🇳
Standard lattice calculations in kaon physics are based on the evaluation of matrix elements of local operators between two single-hadron states or a single-hadron state and the vacuum. Recent progress in lattice QCD has gone beyond these standard observables. I will review the status and prospects of lattice kaon physics with an emphasis on non-leptonic $K \to π π$ decay and long-distance processes including $K^{0}$ - $K^{0}$ mixing and rare kaon decays.
↳ hep-lathep-exhep-phEPJ Web Conf.(2018)·7 citations
31*
On the $D_{s}^{*}$ and charmonia leptonic decays
Gabriela Bailas🇫🇷 · Benoît Blossier🇫🇷 · Jochen Heitger🇩🇪 · Vincent Morénas🇫🇷 · Matthias Post🇩🇪
Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about the $R_{D_{s}}$ ratio, a test of lepton flavour universality equivalent to $R_{D}$ , already measured, but with the $s$ quark as spectator, are awaited in coming years to constrain the corner of an extended Higgs sector with charged doublets. On another side, leptonic widths of pseudoscalar quarkonia are particularly interesting to test an extended Higgs sector with a light CP-odd Higgs boson singlet, through the study of its mixing with quarkonia states. Hadronic parameters entering those processes have to be determined from lattice QCD with enough confidence on the control of systematic errors. We report on the very first step of a long-term program tackled with $N_{f} = 2$ Wilson-Clover fermions to put relevant constraints on extensions of the Higgs sector: extraction of decay constants of $D_{s}^{*}$ , $η_{c}$ , $η_{c} (2 S)$ , $J / ψ$ and $ψ (2 S)$ with lattice ensembles provided by the CLS effort, considering 2 lattice spacings and a large range of pion masses to estimate cut-off effects and extrapolate results to the chiral limit.
↳ hep-lathep-phEPJ Web Conf.(2018)·3 citations
32*
Perturbations against a Q-ball: Charge, energy, and additivity property
Mikhail N. Smolyakov🇷🇺
In the present paper, perturbations against a Q-ball solution are considered. It is shown that if we calculate the U(1) charge and the energy of the modes, which are solutions to linearized equations of motion, up to the second order in perturbations, we will get incorrect results. In particular, for the time-dependent modes we will obtain nonzero terms, which explicitly depend on time, indicating the nonconservation over time of the charge and the energy. It is shown that, as expected, this problem can be resolved by considering nonlinear equations of motion for the perturbations, providing second-order corrections to the solutions of linearized equations of motion. It turns out that contributions of these corrections to the charge and the energy can be taken into account without solving explicitly the nonlinear equations of motion for the perturbations. It is also shown that the use of such nonlinear equations not only recovers the conservation over time of the charge and the energy but also results in the additivity of the charge and the energy of different modes forming the perturbation.
↳ hep-thhep-phPRD(2018)·26 citations
33*
Phenomenological consequences of superfluid dark matter with baryon-phonon coupling
Lasha Berezhiani🇩🇪 · Benoit Famaey🇫🇷 · Justin Khoury🇺🇸
Recently, a new form of dark matter has been suggested to naturally reproduce the empirically successful aspects of Milgrom's law in galaxies. The dark matter particle candidates are axion-like, with masses of order eV and strong self-interactions. They Bose-Einstein condense into a superfluid phase in the central regions of galaxy halos. The superfluid phonon excitations in turn couple to baryons and mediate an additional long-range force. For a suitable choice of the superfluid equation of state, this force can mimic Milgrom's law. In this paper we develop in detail some of the main phenomenological consequences of such a formalism, by revisiting the expected dark matter halo profile in the presence of an extended baryon distribution. In particular, we show how rotation curves of both high and low surface brightness galaxies can be reproduced, with a slightly rising rotation curve at large radii in massive high surface brightness galaxies, thus subtly different from Milgrom's law. We finally point out other expected differences with Milgrom's law, in particular in dwarf spheroidal satellite galaxies, tidal dwarf galaxies, and globular clusters, whose Milgromian or Newtonian behavior depends on the position with respect to the superfluid core of the host galaxy. We also expect ultra-diffuse galaxies within galaxy clusters to have velocities slightly above the baryonic Tully-Fisher relation. Finally, we note that, in this framework, photons and gravitons follow the same geodesics, and that galaxy-galaxy lensing, probing larger distances within galaxy halos than rotation curves, should follow predictions closer to the standard cosmological model than those of Milgrom's law.
↳ astro-ph.COastro-ph.GAgr-qchep-phJCAP(2018)·82 citations
34*
Reexploration of interacting holographic dark energy model: Cases of interaction term excluding the Hubble parameter
Hai-Li Li🇨🇳 · Jing-Fei Zhang🇨🇳 · Lu Feng🇨🇳 · Xin Zhang🇨🇳
In this paper, we make a deep analysis for the five typical interacting holographic dark energy models with the interaction terms $Q = 3 β H_{0} ρ_{de}$ , $Q = 3 β H_{0} ρ_{c}$ , $Q = 3 β H_{0} (ρ_{de} + ρ_{c})$ , $Q = 3 β H_{0} ρ_{de} ρ_{c}$ , and $Q = 3 β H_{0} \frac{ρ _{de} ρ _{c}}{ρ _{de} + ρ _{c}}$ , respectively. We obtain observational constraints on these models by using the type Ia supernova data (the Joint Light-curve Analysis sample), the cosmic microwave background data (Planck 2015 distance priors), the baryon acoustic oscillations data, and the direct measurement of the Hubble constant. We find that the values of $χ_{min}^{2}$ for all the five models are almost equal (around~699), indicating that the current observational data equally favor these IHDE models. In addition, a comparison with the cases of interaction term involving the Hubble parameter $H$ is also made.
↳ astro-ph.COgr-qchep-phEPJC(2017)·22 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.