HEP Phenomenology·hep-ph

Mon·Apr 23, 2018Monday·April 23, 2018

26 papers—21 primary·5 cross-listed·reconstructed*

01*
Electroweak Phase Transition and Baryogenesis in Composite Higgs Models
Sebastian Bruggisser🇩🇪 · Benedict von Harling🇩🇪 · Oleksii Matsedonskyi🇩🇪 · Geraldine Servant🇩🇪
We present a comprehensive study of the electroweak phase transition in composite Higgs models, where the Higgs arises from a new, strongly-coupled sector which confines near the TeV scale. This work extends our study in Ref. [1]. We describe the confinement phase transition in terms of the dilaton, the pseudo-Nambu-Goldstone boson of broken conformal invariance of the composite Higgs sector. From the analysis of the joint Higgs-dilaton potential we conclude that in this scenario the electroweak phase transition can naturally be first-order, allowing for electroweak baryogenesis. We then extensively discuss possible options to generate a sufficient amount of CP violation - another key ingredient of baryogenesis - from quark Yukawa couplings which vary during the phase transition. For one such an option, with a varying charm quark Yukawa coupling, we perform a full numerical analysis of tunnelling in the Higgs-dilaton potential and determine regions of parameter space which allow for successful baryogenesis. This scenario singles out the light dilaton region while satisfying all experimental bounds. We discuss future tests. Our results bring new opportunities and strong motivations for electroweak baryogenesis.
hep-phJHEP(2018)·189 citations
02*
NMSSM with generalized deflected mirage mediation
Xiao Kang Du🇨🇳 · Guo-Li Liu🇨🇳 · Fei Wang🇨🇳 · Wenyu Wang🇨🇳 · Jin Min Yang🇨🇳 · Yang Zhang🇦🇺
We propose to generate a realistic soft SUSY breaking spectrum for Next-to-Minimal Supersymmetric Standard Model (NMSSM) with a generalized deflected mirage mediation scenario, in which additional Yukawa and gauge mediation contributions are included to deflect the renormalization group equation(RGE) trajectory. Based on the Wilsonian effective action obtained by integrating out the messengers, the NMSSM soft SUSY breaking spectrum can be given analytically at the messenger scale. We find that additional contributions to $m_{S}^{2}$ can possibly ameliorate the stringent constraints from the electroweak symmetry breaking (EWSB) and 125 GeV Higgs mass. Constraints from dark matter and fine-tuning are also discussed. The Barbieri-Giudice fine-tuning measure and electroweak fine-tuning measure in our scenario can be as low as $O (1)$ , which possibly indicates that our scenario is natural.
hep-phEPJC(2019)·6 citations
03*
The 21cm Absorption Line and Axion Quark Nugget Dark Matter Model
K. Lawson🇨🇦 · A.R. Zhitnitsky🇨🇦
We argue that dark matter in the form of macroscopically large nuggets of standard model quarks and antiquarks can help to alleviate the tension between standard model cosmology and the recent EDGES observation of a stronger than anticipated 21 cm absorption feature. The effect occurs as a result of the thermal emission from quark nugget dark matter at early times and at energies well below the peak of the CMB. Similar radiation at early times may also contribute a fraction of the GHz range excess observed by ARCADE2.
hep-phastro-ph.COPhys.Dark Univ.(2019)·59 citations
04*
NLO QCD corrections to SM-EFT dilepton and electroweak Higgs boson production, matched to parton shower in POWHEG
Simone Alioli🇮🇹 · Wouter Dekens🇺🇸 · Michael Girard🇵🇱 · Emanuele Mereghetti🇺🇸
We discuss the Standard Model Effective Field Theory (SM-EFT) contributions to neutral- and charge-current Drell-Yan production, associated production of the Higgs and a vector boson, and Higgs boson production via vector boson fusion. We consider all the dimension-six SM-EFT operators that contribute to these processes at leading order, include next-to-leading order QCD corrections, and interface them with parton showering and hadronization in Pythia8 according to the POWHEG method. We discuss existing constraints on the coefficients of dimension-six operators and identify differential and angular distributions that can differentiate between different effective operators, pointing to specific features of Beyond-the-Standard-Model physics.
hep-phhep-exJHEP(2018)·82 citations
05*
The Muon g-2 in Progress
Fred Jegerlehner🇩🇪
Two next generation muon $g - 2$ experiments at Fermilab in the US and at J-PARC in Japan have been designed to reach a four times better precision from 0.54 ppm to 0.14 ppm and the challenge for the theory side is to keep up in precision as far as possible. This has triggered a lot of new research activities. The main motivation is the persisting 3 to 4 $σ$ deviation between standard theory and experiment. As Standard Model predictions almost without exception match perfectly all other experimental information, the deviation in one of the most precisely measured quantities in particle physics remains a mystery and inspires the imagination of model builders. Plenty of speculations are aiming to explain what beyond the Standard Model effects could fill what seems to be missing. Here very high precision experiments are competing with searches for new physics at the high energy frontier lead by the Large Hadron Collider at CERN. Actually, the tension is increasing steadily as no new states are found which could accommodate the $g_{μ} - 2$ discrepancy. With the new muon $g - 2$ experiments this discrepancy would go up at least to 6 $σ$ , in case the central values do not move, up to 10 $σ$ could be reached if the present theory error could be reduced by a factor of two. Interestingly, the new $α$ from Berkeley by R. H. Parker et al. Science 360, 191 (2018): $α^{- 1} (Cs18) = 137.035999046 (27)$ gives an $a_{e}$ prediction $a_{e} = 0.00115965218157 (23)$ such that $a_{e}^{exp} - a_{e}^{the} = (- 84 \pm 36) \times 1 0^{- 14}$ shows a $- 2.3 σ$ deviation now.
hep-phActa Phys.Polon.B(2018)·57 citations
06*
Constraints on new physics from $K \to π ν ν ˉ$
Xiao-Gang He🇹🇼 · German Valencia🇦🇺 · Keith Wong🇦🇺
We study generic effects of new physics on the rare decay modes $K_{L} \to π^{0} ν ν ˉ$ and $K^{+} \to π^{+} ν ν ˉ$ . We discuss several cases: left-handed neutrino couplings; right handed neutrino couplings; neutrino lepton flavour violating (LFV) interactions; and $Δ I = 3/2$ interactions. The first of these cases has been studied before as it covers many new physics extensions of the standard model; the second one requires the existence of a new light (sterile) right-handed neutrino and its contribution to both branching ratios is always additive to the SM. The case of neutrino LFV couplings introduces a CP conserving contribution to $K_{L} \to π^{0} ν ν ˉ$ which affects the rates in a similar manner as a right handed neutrino as neither one of these interferes with the standard model amplitudes. Finally, we consider new physics with $Δ I = 3/2$ interactions to go beyond the Grossman-Nir bound. We find that the rare kaon rates are only sensitive to new physics scales up to a few GeV for this scenario.
hep-phhep-exEPJC(2018)·30 citations
07*
Production of Purely Gravitational Dark Matter
Yohei Ema🇯🇵 · Kazunori Nakayama🇯🇵 · Yong Tang🇰🇷
In the purely gravitational dark matter scenario, the dark matter particle does not have any interaction except for gravitational one. We study the gravitational particle production of dark matter particle in such a minimal setup and show that correct amount of dark matter can be produced depending on the inflation model and the dark matter mass. In particular, we carefully evaluate the particle production rate from the transition epoch to the inflaton oscillation epoch in a realistic inflation model and point out that the gravitational particle production is efficient even if dark matter mass is much larger than the Hubble scale during inflation as long as it is smaller than the inflaton mass.
hep-phastro-ph.COJHEP(2018)·198 citations
08*
Flavor physics in the multi-Higgs doublet models induced by the left-right symmetry
Syuhei Iguro🇯🇵 · Yu Muramatsu🇨🇳 · Yuji Omura🇯🇵 · Yoshihiro Shigekami🇯🇵
In this paper, we discuss the multi-Higgs doublet models, that could be effectively induced by the extended Standard Model (SM). In particular, we focus on the phenomenology in the supersymmetric model with left-right (LR) symmetry, where the down-type and the up-type Yukawa couplings are unified and the Yukawa coupling matrices are expected to be hermitian. In this model, several Higgs doublets are introduced to realize the realistic fermion mass matrices, and the heavy Higgs doublets have flavor changing couplings with quarks and leptons. The LR symmetry is assumed to break down at high energy to realize the Type-I seesaw mechanism. The supersymmetry breaking scale is expected to be around 100 TeV to achieve the 125 GeV Higgs. In such a setup, the flavor-dependent interaction of the Higgs fields becomes sizable, so that we especially discuss the flavor physics induced by the heavy Higgs fields in our work. Our prediction depends on the structure of neutrinos, e.g., the neutrino mass ordering. We demonstrate how the flavor structure of the SM affects the flavor violating couplings. In our analysis, we mainly focus on the four-fermi interaction induced by the scalar exchanging, and we propose a simple parameterization for the coefficients. Then, we find the correlations among the flavor observables and, for instance, see that our prediction for the $μ \to 3 e$ process could be covered by the future experiment, in one case where the neutrino mass hierarchy is normal.
hep-phJHEP(2018)·18 citations
09*
DAMA/LIBRA-phase2 in WIMP effective models
Sunghyun Kang🇰🇷 · Stefano Scopel🇰🇷 · Gaurav Tomar🇰🇷 · Jong-Hyun Yoon (Sogang U.)🇰🇷
The DAMA/LIBRA collaboration has recently released updated results from their search for the annual modulation signal expected from Dark Matter (DM) scattering in their NaI detectors. We have fitted the updated DAMA result for the modulation amplitudes in terms of a Weakly Interacting Massive Particle (WIMP) signal, parameterizing the interaction with nuclei in terms of the most general effective Lagrangian for a WIMP particle spin up to 1/2, systematically assuming dominance of one of the 14 possible interaction terms, and assuming for the WIMP velocity distribution a standard Maxwellian. We find that most of the couplings of the non-relativistic effective Hamiltonian can provide a better fit compared to the standard Spin Independent interaction case, and with a reduced fine-tuning of the three parameters (WIMP mass, WIMP-nucleon effective cross-section and ratio between the WIMP-neutron and the WIMP-proton couplings). Moreover, effective models for which the cross section depends explicitly on the WIMP incoming velocity can provide a better fit of the DAMA data at large values of $m_{χ}$ compared to the standard velocity-independent cross-section due to a different phase of the modulation amplitudes. All the best fit solutions are in tension with exclusion plots of both XENON1T and PICO60.
hep-phastro-ph.COJCAP(2018)·36 citations
10*
Cosmic-ray fermion decay through tau-antitau emission with Lorentz violation
C. A. Escobar🇲🇽 · J. P. Noordmans🇵🇹 · R. Potting🇵🇹
We study CPT and Lorentz violation in the tau-lepton sector of the Standard Model in the context of the Standard-Model Extension, described by a coefficient which is thus far unbounded by experiment. We show that any non-zero value of this coefficient implies that, for sufficiently large energies, standard-model fermions become unstable against decay due to the emission of a pair of tau-antitau leptons. We calculate the induced fermion energy-loss rate and we deduce the first limit on the Lorentz- and CPT-violating coefficient.
hep-phPRD(2018)·10 citations
11*
New Inflation in Supersymmetric SU(5) and Flipped SU(5) GUT Models
Mansoor Ur Rehman🇵🇰 · Mian Muhammad Azeem Abid🇵🇰 · Amna Ejaz🇵🇰
We study the feasibility of realizing supersymmetric new inflation model, introduced by Senoguz and Shafi in [1], for $S U (5)$ and flipped $S U (5)$ models of grand unified theories (GUTs). This realization requires an additional $U (1)_{R} \times Z_{n}$ symmetry for its successful implementation. The standard model (SM) gauge singlet scalar components of $2 4_{H}$ and $1 0_{H}$ GUT Higgs superfields are respectively employed to realize successful inflation in $S U (5)$ and flipped $S U (5)$ models. The predictions of the various inflationary observables lie within the recent Planck bounds on the scalar spectral index, $n_{s}$ , for $n \geq 5$ in $S U (5)$ model and for $n \geq 6$ in flipped $S U (5)$ model. In particular, the tensor to scalar ratio $r$ and the running of spectral index $d n_{s} / d ln k$ are negligibly small and lie in the range, $1 0^{- 12} ≲ r ≲ 1 0^{- 8}$ and $1 0^{- 9} ≲ d n_{s} / d ln k ≲ 1 0^{- 3}$ , for realistic values of $n$ . In numerical estimation of the various predictions, we fix the gauge symmetry breaking scale, $M$ , around $2 \times 1 0^{16}$ GeV. The issue of gauge coupling unification in $R$ -symmetric $S U (5)$ is evaded by adding vectorlike families with mass splitting within their multiplets. The dilution of monopoles beyond the observable limit is naturally achieved in the breaking of $S U (5)$ gauge symmetry during inflation. A realistic scenario of reheating with non-thermal leptogenesis is employed for both models. The predicted range of reheat temperature within Planck bounds, $3 \times 1 0^{7} GeV ≲ T_{r} ≲ 2 \times 1 0^{9}$ GeV, is safe from the gravitino problem for the gravitino mass, $m_{3/2} ≳ 10$ TeV. Finally, the $U (1)_{R} \times Z_{n}$ symmetry is also observed to play a crucial role in suppressing the various fast proton decay operators.
hep-phJCAP(2020)·18 citations
12*
Bottom-quark effects in Higgs production at intermediate transverse momentum
Fabrizio Caola🇬🇧 · Jonas M. Lindert🇬🇧 · Kirill Melnikov🇩🇪 · Pier Francesco Monni🇨🇭 · Lorenzo Tancredi🇨🇭 · Christopher Wever🇩🇪
We provide a precise description of the Higgs boson transverse momentum distribution including top and bottom quark contributions, that is valid for transverse momenta in the range mb < pt < mt, where mb and mt are the bottom and top quark masses. This description is based on a combination of fixed next-to-leading order (NLO) results with next-to-next-to-leading logarithmic (NNLL) transverse momentum resummation. We show that ambiguities in the resummation procedure for the b-quark loops are of the same order as the related fixed-order uncertainties. We conclude that the current uncertainty in the top-bottom interference contribution to the Higgs transverse momentum spectrum is O(20%).
hep-phhep-exJHEP(2018)·36 citations
13*
A cosmological pathway to testable leptogenesis
Bhaskar Dutta🇺🇸 · Chee Sheng Fong🇧🇷 · Esteban Jimenez🇺🇸 · Enrico Nardi🇮🇹
Leptogenesis could have occurred at temperatures much lower than generally thought, if the cosmological history of the Universe underwent a period of accelerated expansion, as is predicted for example in a class of scalar-tensor theories of gravitation. We discuss how non-standard cosmologies can open new pathways for low scale leptogenesis. Within these scenarios, direct tests of leptogenesis could also provide information on the very early times Universe evolution, corresponding to temperatures larger than the TeV.
hep-phastro-ph.COJCAP(2018)·27 citations
14*
Azimuthal polarization of polarized top quark in noncommutative standard model
Z. Rezaei🇮🇷 · R. Salehi🇮🇷
Top quark decays before hadronization and its information transfer to final products. The top quark decays via the weak interaction, hence the azimuthal polarized decay rate is zero in the leading order of SM. Therefore the study of top quark could be taken into consideration as useful tools to search for new physics. In this paper, we calculate the decay of polarized top quark in the framework of the noncommutative standard model. We investigate the contribution of noncommutative space-time on the azimuthal polarized decay rate and spin analyzing power. Also we depict the energy spectrum for the charged lepton and the variation of the total differential decay rate with respect to the azimuthal angle which receive some correction in noncommutative space-time.
hep-phAnnals Phys.(2019)·7 citations
15*
Primordial Black Holes from Higgs Vacuum Instability: Avoiding Fine-tuning through an Ultraviolet Safe Mechanism
José Ramón Espinosa🇪🇸 · Davide Racco🇨🇭 · Antonio Riotto🇨🇭
We have recently proposed the idea that dark matter in our universe is formed by primordial black holes generated by Standard Model Higgs fluctuations during inflation and thanks to the fact that the Standard Model Higgs potential develops an instability at a scale of the order of $1 0^{11}$ GeV. In this sense, dark matter does not need any physics beyond the Standard Model, although the mechanism needs fine-tuning to avoid the overshooting of the Higgs into the dangerous AdS vacuum. We show how such fine-tuning can be naturally avoided by coupling the Higgs to a very heavy scalar with mass $≫ 1 0^{11}$ GeV that stabilises the potential in the deep ultraviolet, but preserving the basic feature of the mechanism which is built within the Standard Model.
hep-phastro-ph.COgr-qchep-thEPJC(2018)·25 citations
16*
A Cosmological Signature of the SM Higgs Instability: Gravitational Waves
José Ramón Espinosa🇪🇸 · Davide Racco🇨🇭 · Antonio Riotto🇨🇭
A fundamental property of the Standard Model is that the Higgs potential becomes unstable at large values of the Higgs field. For the current central values of the Higgs and top masses, the instability scale is about $1 0^{11}$ GeV and therefore not accessible by colliders. We show that a possible signature of the Standard Model Higgs instability is the production of gravitational waves sourced by Higgs fluctuations generated during inflation. We fully characterise the two-point correlator of such gravitational waves by computing its amplitude, the frequency at peak, the spectral index, as well as their three-point correlators for various polarisations. We show that, depending on the Higgs and top masses, either LISA or the Einstein Telescope and Advanced-Ligo, could detect such stochastic background of gravitational waves. In this sense, collider and gravitational wave physics can provide fundamental and complementary informations. Furthermore, the consistency relation among the three- and the two-point correlators could provide an efficient tool to ascribe the detected gravitational waves to the Standard Model itself. Since the mechanism described in this paper might also be responsible for the generation of dark matter under the form of primordial black holes, this latter hypothesis may find its confirmation through the detection of gravitational waves.
hep-phastro-ph.COgr-qchep-thJCAP(2018)·465 citations
17*
Supernova neutrino physics with a nuclear emulsion detector
Giovanni De Lellis🇮🇹 · Antonia Di Crescenzo🇮🇹 · Andrea Gallo Rosso🇮🇹 · Valerio Gentile🇮🇹 · Francesco Vissani🇮🇹
The existence of the coherent neutrino-nucleus scattering reaction requires to evaluate, for any detector devoted to WIMP searches, the irreducible background due to conventional neutrino sources and at same time, it gives a unique chance to reveal supernova neutrinos. We report here a detailed study concerning a new directional detector, based on the nuclear emulsion technology. A Likelihood Ratio test shows that, in the first years of operations and with a detector mass of several tens of tons, the observation of the supernova signal can be achieved. The determination of the distance of the supernova from the neutrinos and the observation of $^{8}$ B neutrinos are also discussed.
hep-phphysics.ins-detJCAP(2018)·0 citations
18*
Signal mixture estimation for degenerate heavy Higgses using a deep neural network
Anders Kvellestad🇳🇴 · Steffen Maeland🇳🇴 · Inga Strümke🇳🇴
If a new signal is established in future LHC data, a next question will be to determine the signal composition, in particular whether the signal is due to multiple near-degenerate states. We investigate the performance of a deep learning approach to signal mixture estimation for the challenging scenario of a ditau signal coming from a pair of degenerate Higgs bosons of opposite CP charge. This constitutes a parameter estimation problem for a mixture model with highly overlapping features. We use an unbinned maximum likelihood fit to a neural network output, and compare the results to mixture estimation via a fit to a single kinematic variable. For our benchmark scenarios we find a ~20% improvement in the estimate uncertainty.
hep-phhep-exEPJC(2018)·6 citations
19*
Elliptic flow and $R_{AA}$ of D mesons at FAIR comparing the UrQMD hybrid model and the coarse-graining approach
Gabriele Inghirami🇩🇪 · Hendrik van Hees🇩🇪 · Stephan Endres🇩🇪 · Juan M. Torres-Rincon🇺🇸 · Marcus Bleicher🇩🇪
We present a study of the elliptic flow and $R_{AA}$ of D and anti-D mesons in Au+Au collisions at FAIR energies. We propagate the charm quarks and the D mesons following a previously applied Langevin dynamics. The evolution of the background medium is modeled in two different ways: (I) we use the UrQMD hydrodynamics + Boltzmann transport hybrid approach including a phase transition to QGP and (II) with the coarse-graining approach employing also an equation of state with QGP. The latter approach has previously been used to describe di-lepton data at various energies very successfully. This comparison allows us to explore the effects of partial thermalization and viscous effects on the charm propagation. We explore the centrality dependencies of the collisions, the variation of the decoupling temperature and various hadronization parameters. We find that the initial partonic phase is responsible for the creation of most of the D mesons elliptic flow and that the subsequent hadronic interactions seem to play only a minor role. This indicates that D mesons elliptic flow is a smoking gun for a partonic phase at FAIR energies. However, the results suggest that the magnitude and the details of the elliptic flow strongly depend on the dynamics of the medium and on the hadronization procedure, which is related to the medium properties as well. Therefore, even at FAIR energies the charm quark might constitute a very useful tool to probe the Quark-Gluon Plasma and investigate its physics.
hep-phhep-exnucl-thEPJC(2019)·10 citations
20*
Sneutrino Dark Matter, Constraints and Perspectives
Luigi Delle Rose🇬🇧 · Shaaban Khalil🇪🇬 · Simon J.D. King🇬🇧 · Suchita Kulkarni🇦🇹 · Carlo Marzo🇪🇪 · Stefano Moretti🇬🇧 · Cem S. Un🇹🇷
The prevalent Dark Matter (DM) candidate of the (B-L) Supersymmetric Standard Model (BLSSM) is the Right Handed (RH) sneutrino. In this work we assess the ability of ground and space based experiments to establish the nature of this particle, through indirect and collider detection.
hep-ph2 citations
21*
Single-top associated production with a $Z$ or $H$ boson at the LHC: the SMEFT interpretation
Celine Degrande🇨🇭 · Fabio Maltoni🇧🇪 · Ken Mimasu🇧🇪 · Eleni Vryonidou🇨🇭 · Cen Zhang🇨🇳
At the LHC, top quarks can be produced singly with a sizeable rate via electroweak interactions. This process probes a limited set of top-quark electroweak couplings, i.e. , the same entering the top-quark decay, yet at higher scales and with a different sensitivity. Requiring the production of a $Z$ or $H$ boson in association with single-top significantly extends the sensitivity of this process to new physics, opening up the unique possibility of testing top-Higgs, top-gauge, triple gauge, gauge-Higgs interactions without being dominated by QCD interactions. We consider $tZ j$ and $t H j$ production at the LHC, providing predictions at next-to-leading accuracy in QCD in the framework of the standard model effective field theory, including all relevant operators up to dimension six. We perform the first complete study of the sensitivity to new interactions of these processes, highlighting the interplay and complementarity among $t j$ , $tZ j$ and $t H j$ in simultaneously constraining top-quark, triple gauge, and gauge-Higgs interactions in the current and future runs at the LHC.
hep-phJHEP(2018)·106 citations
22*
A Note on 4D Heterotic String Vacua, FI-terms and the Swampland
Gerardo Aldazabal🇦🇷 · Luis E. Ibáñez🇪🇸
We present a conjecture for the massless sector of perturbative 4D $N = 1$ heterotic $(0, 2)$ string vacua, including $U (1)^{n}$ gauge symmetries,one of them possibly anomalous (like in standard heterotic compactifications). Mathematically it states that the positive hull generated by the charges of the massless chiral multiplets spans a sublattice of the full charge lattice. We have tested this conjecture in many heterotic $N = 1$ compactifications in 4D. Our motivation for this conjecture is that it allows to understand a very old puzzle in $(0, 2)$ $N = 1$ heterotic compactification with an anomalous $U (1)$ . The conjecture guarantees that there is always a D-flat direction cancelling the FI-term and restoring $N = 1$ SUSY in a nearby vacuum. This is something that has being verified in the past in a large number of cases, but whose origin has remained obscure for decades. We argue that the existence of this lattice of massless states guarantees the instability of heterotic non-BPS extremal blackholes, as required by Weak Gravity Conjecture arguments. Thus the pervasive existence of these nearby FI-cancelling vacua would be connected with WGC arguments.
↳ hep-thgr-qchep-phPLB(2018)·18 citations
23*
Flux compactifications and naturalness
Wilfried Buchmuller🇩🇪 · Markus Dierigl🇳🇱 · Emilian Dudas🇫🇷
Free massless scalars have a shift symmetry. This is usually broken by gauge and Yukawa interactions, such that quantum corrections induce a quadratically divergent mass term. In the Standard Model this leads to the hierarchy problem of the electroweak theory, the question why the Higgs mass is so much smaller than the Planck mass. We present an example where a large scalar mass term is avoided by coupling the scalar to an infinite tower of massive states which are obtained from a six-dimensional theory compactified on a torus with magnetic flux. The series of divergent quantum corrections adds up to zero, and we show explicitly that the shift symmetry of the scalar is preserved in the effective four-dimensional theory despite the presence of gauge and Yukawa interaction terms.
↳ hep-thhep-phJHEP(2018)·31 citations
24*
Hybrid Quasi-Single Field Inflation
Yi Wang🇨🇳 · Yi-Peng Wu🇯🇵 · Jun'ichi Yokoyama🇯🇵 · Siyi Zhou🇨🇳
The decay of massive particles during inflation generates characteristic signals in the squeezed limit of the primordial bispectrum. These signals are in particular distinctive in the regime of the quasi-single field inflation, where particles are oscillating with masses comparable to the Hubble scale. We apply the investigation to a class of scalar particles that experience a so-called waterfall phase transition in the isocurvature direction driven by the symmetry-breaking mechanism based on the hybrid inflation scenario. With a time-varying mass, a novel shape of oscillatory bispectrum is presented as the signature of a waterfall phase transition during inflation.
↳ astro-ph.COhep-phhep-thJCAP(2018)·26 citations
25*
Quasielastic charged-current neutrino scattering in the scaling model with relativistic effective mass
I. Ruiz Simo🇪🇸 · V.L. Martinez-Consentino🇪🇸 · J.E. Amaro🇪🇸 · E. Ruiz Arriola🇪🇸
We use a recent scaling analysis of the quasielastic electron scattering data from $^{12}$ C to predict the quasielastic charge-changing neutrino scattering cross sections within an uncertainty band. We use a scaling function extracted from a selection of the $(e, e^{'})$ cross section data, and an effective nucleon mass inspired by the relativistic mean-field model of nuclear matter. The corresponding super-scaling analysis with relativistic effective mass (SuSAM*) describes a large amount of the electron data lying inside a phenomenological quasielastic band. The effective mass incorporates the enhancement of the transverse current produced by the relativistic mean field. The scaling function incorporates nuclear effects beyond the impulse approximation, in particular meson-exchange currents and short range correlations producing tails in the scaling function. Besides its simplicity, this model describes the neutrino data as reasonably well as other more sophisticated nuclear models.
↳ nucl-thhep-phPRD(2018)·23 citations
26*
Calculating hard probe radiative energy loss beyond soft-gluon approximation: Examining the approximation validity
Bojana Blagojevic🇷🇸 · Magdalena Djordjevic🇷🇸 · Marko Djordjevic🇷🇸
The soft-gluon approximation, which implies that radiated gluon carries away a small fraction of initial parton's energy, is a commonly used assumption in calculating radiative energy loss of high momentum partons traversing QGP created at RHIC and LHC. While soft-gluon approximation is convenient, different theoretical approaches reported significant radiative energy loss of high $p_{⊥}$ partons, thereby questioning its validity. To address this issue, we relaxed the soft-gluon approximation within DGLV formalism. The obtained analytical expressions are quite distinct compared to the soft-gluon case. However, numerical results for the first order in opacity fractional energy loss lead to small differences in predictions for the two cases. The difference in the predicted number of radiated gluons is also small. Moreover, the effect on these two variables has an opposite sign, which when combined results in almost overlapping suppression predictions. Therefore, our results imply that, contrary to the commonly held doubts, the soft-gluon approximation in practice works surprisingly well in DGLV formalism. Finally, we also discuss generalizing this relaxation in the dynamical QCD medium, which suggests a more general applicability of the conclusions obtained here.
↳ nucl-thhep-phPRC(2019)·29 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.