HEP Phenomenology·hep-ph

Fri·Sep 3, 2021Friday·September 3, 2021

18 papers—12 primary·6 cross-listed·reconstructed*

01*
Curing tachyonic tree-level syndrome in NMSSM light-singlet scenarios
Florian Domingo🇩🇪 · Sebastian Paßehr🇩🇪
Models with an extended Higgs sector open up the phenomenological possibility of additional scalars, beyond the SM-like boson observed by the LHC, with mass at or below the electroweak scale. Such scenarios are in particular viable in the presence of electroweak-singlet spin-0 fields, as expected for instance in the context of the NMSSM. Given that the size of radiative corrections can substantially affect the Higgs potential, a negative squared mass at the tree level does not necessarily yield a tachyonic spectrum at the physical level, but only indicates a failure of the tree-level description for calculational purposes. We explain how to tackle this technical issue in the example of the NMSSM, in scenarios with light CP-odd or CP-even singlet-dominated states and show how loop corrections to the Higgs masses and decay widths can be derived with the regularized Lagrangian. We further explore how the same flexibility in the definition of tree-level parameters can be exploited to circumvent large deviations of the tree-level spectrum from the kinematical setup in Higgs decays, or to estimate the theoretical uncertainty associated with the discrepancy between tree-level and physical Higgs spectra. The latter is of particular relevance for the properties of the SM-like Higgs boson in supersymmetry-inspired models.
hep-phEPJC(2022)·2 citations
02*
Probing isovector scalar mesons in the charmless three-body $B$ decays
Jian Chai🇨🇳 · Shan Cheng🇨🇳 · Ai-Jun Ma🇨🇳
We propose to study the multiparticle configurations of isovector scalar mesons, saying $a_{0} (980)$ and $a_{0} (1450)$ , in the charmless three-body $B$ decays by considering the width effects. Two scenarios of $a_{0}$ configurations are assumed, in which the first one take $a_{0} (980)$ as the lowest-lying $q q ˉ$ state and $a_{0} (1450)$ as the first radial excited state, the second one take $a_{0} (1450)$ as the lowest-lying $q q ˉ$ state and $a_{0} (1950)$ as the first radial excited state while $a_{0} (980)$ is not a $q q ˉ$ state. Within these two scenarios, we do the PQCD calculation for the quasi-two-body $B \to a_{0} [\to K K ˉ / π η] h$ decays and extract the corresponding branching fractions of two-body $B \to a_{0} h$ decays under the narrow width approximation. Our predictions show that the first scenario of $a_{0} (980)$ configuration can not be excluded by the available measurements in $B$ decays, the contributions from $a_{0} (1450)$ to the branching fractions in most channels are comparable in the first and second scenarios. Several channels are suggested for the forthcoming experimental measurements to reveal the multiparticle configurations of $a_{0}$ , such as the channel $B^{0} \to a_{0}^{-} (980) [\to π^{-} η] π^{+}$ with the largest predicted branching fraction, the channels $B^{0} \to a_{0}^{\pm} (1450) [\to K^{\pm} K ˉ^{0}, π^{\pm} η] π^{\mp}$ whose branching fractions obtained in the second scenario is about three times larger in magnitude than that obtained in the first scenario, and also the channels $B^{+} \to a_{0}^{+} (1950) [K^{+} K ˉ^{0} / π^{+} η] K^{0}$ whose branching fractions are linear dependent on the partial width $Γ_{a_{0} (1950) \to K K / π η}$ .
hep-phPRD(2022)·14 citations
03*
Bayesian Monte Carlo extraction of sea asymmetry with SeaQuest and STAR data
C. Cocuzza🇺🇸 · W. Melnitchouk🇺🇸 · A. Metz🇺🇸 · N. Sato🇺🇸
We perform a global QCD analysis of unpolarized parton distributions within a Bayesian Monte Carlo framework, including the new $W$ -lepton production data from the STAR Collaboration at RHIC and Drell-Yan di-muon data from the SeaQuest experiment at Fermilab. We assess the impact of these two new measurements on the light antiquark sea in the proton, and the $d ˉ - u ˉ$ asymmetry in particular. The SeaQuest data are found to significantly reduce the uncertainty on the $d ˉ / u ˉ$ ratio at large parton momentum fractions $x$ , strongly favoring an enhanced $d ˉ$ sea up to $x \approx 0.4$ , in general agreement with nonperturbative calculations based on chiral symmetry breaking in QCD.
hep-phhep-exnucl-thPRD(2021)·50 citations
04*
Bottom Tetraquark Production at RHIC?
R. Vogt🇺🇸 · A. Angerami🇺🇸
Background: A resonance has been observed by the ANDY Collaboration at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory in Cu+Au collisions at center-of-mass energy $s = 200$ GeV and at forward rapidity with an average mass of 18.15 GeV. The Collaboration suggests that it is a $b b b b$ tetraquark state decaying to two $Υ$ (1S) states, each measured through the $Υ \to g g g$ channel. Purpose: Their suggestion is investigated assuming that the two $Υ$ states are produced through the materialization of a $∣ uu d b b b b ⟩$ Fock state in the projectile. Methods: The $Υ$ pair mass and rapidity distributions arising from such a state are calculated. The production of an $X_{b} (b b b b)$ tetraquark state from the same Fock configuration is also investigated. The dependence on bottom quark mass and their transverse momentum range is also studied. Results: It is found that double $Υ$ production from these $∣ uu d b b b b ⟩$ states peak in the rapidity range of the ANDY detector. The $Υ$ pair and $X_{b}$ masses are, however, higher than the mass reported by the ANDY Collaboration. Conclusions: The results obtained from these calculations are incompatible with the ANDY result. They are, however, compatible with previous predictions of $b b b b$ tetraquark masses.
hep-phPRD(2021)·13 citations
05*
Revisit the $Z_{c} (4025)$ structure observed by BESIII in the $e^{+} e^{-} \to (D^{*} D ˉ^{*})^{\pm, 0} π^{\mp, 0}$ reactions at $s = 4.26$ GeV
Man-Yu Duan🇨🇳 · Guan-Ying Wang🇨🇳 · En Wang · De-Min Li🇨🇳 · Dian-Yong chen🇨🇳
Within the framework of the local hidden gauge formalism, we have reanalyzed the hidden-charm vector-vector meson $D^{*} D ˉ^{*}$ , $K^{*} K ˉ^{*}$ , and $ρρ$ interactions with the quantum numbers $I (J^{P}) = 1 (1^{+})$ . The estimation indicates that $D^{*} D ˉ^{*}$ system could form a bound state around 4010 MeV. By comparing our theoretical estimation with the BESIII measurements of the $e^{+} e^{-} \to (D^{*} D ˉ^{*})^{\pm} π^{\mp}$ and $e^{+} e^{-} \to (D^{*} D ˉ^{*})^{0} π^{0}$ reactions at $s = 4.26$ GeV , we find that the enhancement structure of the $Z_{c} (4025)$ in the $D^{*} D ˉ^{*}$ invariant mass distribution observed by BESIII could be interpreted by a shallow $D^{*} D ˉ^{*}$ bound state.
hep-phPRD(2021)·11 citations
06*
The light scalars: four- vs. two-quark states in the complex energy plane from Bethe-Salpeter equations
Nico Santowsky🇩🇪 · Christian S. Fischer🇩🇪
We study the dynamical generation of scalar mesons in the light quark sector ( $q \in {u, d, s}$ ) and calculate the masses and widths for the $f_{0} (500), a_{0} (980)$ and $f_{0} (980)$ . To this end we study the mixing of conventional $q q ˉ$ and `exotic' $q q ˉ q q ˉ$ states via a coupled set of two-body Bethe-Salpeter equations based on a symmetry-preserving truncation of the underlying Dyson-Schwinger equations. This allows us to determine the dominant components of each state. Furthermore, we extend our previous framework into the complex energy plane such that we can study the analytic structure of the states in question and extract their width. At the physical point of small quark masses, the $σ$ meson is predominantly a $π π$ resonance. Consequently, its mass and width is driven by the effects of chiral symmetry breaking. At larger quark masses, however, the conventional $q q ˉ$ components take over. Furthermore, we find a strong molecular $K K ˉ$ component for both, the strange-light $f_{0} (980)$ and the $a_{0} (980)$ .
hep-phPRD(2022)·18 citations
07*
Sterile Neutrinos as Dark Matter Candidates
Joachim Kopp (CERN & JGU Mainz)🇨🇭
In these brief lecture notes, we introduce sterile neutrinos as dark matter candidates. We discuss in particular their production via oscillations, their radiative decay, as well as possible observational signatures and constraints.
hep-phSciPost Phys.Lect.Notes(2022)·22 citations
08*
Approximate NNLO QCD corrections to semi-inclusive DIS
Maurizio Abele🇩🇪 · Daniel de Florian🇦🇷 · Werner Vogelsang🇩🇪
We determine approximate next-to-next-to-leading order (NNLO) corrections to unpolarized and polarized semi-inclusive DIS. They are derived using the threshold resummation formalism, which we fully develop to next-to-next-to-leading logarithmic (NNLL) accuracy, including the two-loop hard factor. The approximate NNLO terms are obtained by expansion of the resummed expression. They include all terms in Mellin space that are logarithmically enhanced at threshold, or that are constant. In terms of the customary SIDIS variables $x$ and $z$ they include all double distributions (that is, "plus" distributions and $δ$ -functions) in the partonic variables. We also investigate corrections that are suppressed at threshold and we determine the dominant terms among these. Our numerical estimates suggest much significance of the approximate NNLO terms, along with a reduction in scale dependence.
hep-phPRD(2021)·54 citations
09*
Soft gluon fields and anomalous magnetic moment of muon
Sergei Nedelko🇷🇺 · Aleksei Nikolskii🇷🇺 · Vladimir Voronin🇷🇺
An impact of nonperturbatively-treated soft gluon modes on the value of anomalous magnetic moment of muon $a_{μ}$ is studied within the mean-field approach to QCD vacuum and hadronization. It is shown that radial excitations of vector mesons strongly enhance contribution of hadronic vacuum polarization to $a_{μ}$ , doubling the contribution of one intermediate meson processes compared to result for ground state mesons. The mean field also strongly influences the hadronic light-by-light scattering contribution due to the Wilson line in quark propagators.
hep-phJ.Phys.G(2022)·4 citations
10*
Triangle singularities waning in Heavy Ion Collisions: the case of $Y (4260) \to π (π J / ψ)$
Luciano M. Abreu🇧🇷 · Felipe J. Llanes-Estrada🇪🇸
We have recently observed that hadron triangle singularities, that can mock new exotic hadrons, can be significanttly suppressed in relativistic heavy ion collisions, provided two conditions are met: these are, first, that the fireball lives long enough so that the triangle process has enough time to complete in the Norton-Coleman classical sense, and second, that the mass and/or width of the particles in the triangle diagram are sufficiently modified from their vacuum values. Here we add a very interesting example to the canon, which is $Y (4260) \to D_{1} D \to π D^{*} D \to π + J / ψ π$ . This reaction has been proposed as a mechanism to explain the appearance of $Z_{c} (3900)$ in the $J / ψ π$ spectrum. If the two muons and two pions reconstructing the initial-state $Y$ can be isolated from the combinatorial background, then the mechanism can provide a spectroscopy test: presence of $Y (4260)$ but absence of $Z_{c} (3900)$ would be more indicative of such triangle mechanism, while presence of both would rather point out to $Z_{c}$ being an exotic hadron.
hep-phNucl.Part.Phys.Proc.(2022)·6 citations
11*
Possible indications for new Higgs bosons in the reach of the LHC: N2HDM and NMSSM interpretations
Thomas Biekötter🇩🇪 · Alexander Grohsjean🇩🇪 · Sven Heinemeyer🇪🇸 · Christian Schwanenberger🇩🇪 · Georg Weiglein🇩🇪
In several searches for additional Higgs bosons at the LHC, in particular in a CMS search exploring decays to pairs of top quarks, $t t ˉ$ , and in an ATLAS search studying tau leptons, $τ^{+} τ^{-}$ , local excesses of about $3 σ$ standard deviations or above have been observed at a mass scale of approximately $400$ GeV. We investigate to what extent a possible signal in these channels could be accommodated in the Next-to-Two-Higgs-Doublet Model (N2HDM) or the Next-to Minimal Supersymmetric Standard Model (NMSSM). In a second step we analyze whether such a model could be compatible with both a signal at around $400$ GeV and $96$ GeV, where the latter possibility is motivated by observed excesses in searches for the $b b ˉ$ final state at LEP and the di-photon final state at CMS. The analysis for the N2HDM reveals that the observed excesses at $400 G e V$ in the $t t ˉ$ and $τ^{+} τ^{-}$ channels point towards different regions of the parameter space, while one such excess and an additional Higgs boson at around $96$ GeV could simultaneously be accommodated. In the context of the NMSSM an experimental confirmation of a signal in the $t t ˉ$ final state would favour the alignment-without-decoupling limit of the model, where the Higgs boson at $125$ GeV could be essentially indistinguishable from the Higgs boson of the standard model. In contrast, a signal in the $τ^{+} τ^{-}$ channel can only be accommodated outside of this limit, and parts of the investigated parameter space could be probed with Higgs signal-rate measurements at the (HL-)LHC.
hep-phEPJC(2022)·88 citations
12*
Determining the Dirac CP violation phase and neutrino mass hierarchy
Z.B.Todorovic🇷🇸
There is still a problem in neutrino physics related to the configuration of neutrino masses: Are neutrinos arranged by masses following the Standard Model as three generations of fundamental particles, Gen III>Gen II>Gen I, thus forming a structural-normal hierarchy, or deviate from that principle? The biggest obstacle that is still present is the sign of the absolute value of the difference of the square of neutrino masses. It was avoided by applying the theory of neutrino oscillation probability for each structure of the neutrino mass hierarchy. With such a theoretical approach the equation of motion was derived for each structure in which the Dirac CP violation phase appeared as an unknown quantity. This enables direct calculation of the explicit value for the Dirac CP violation phase. Two examples were analyzed: The first example is devoted to the normal mass ordering and the second one is devoted to the inverted mass ordering. The data used for theoretical calculations presented in this paper are obtained on the basis of the latest reassessed data by processing the results of experimental measurements. On the basis of the performed calculations, normal mass ordering is unconditionally excluded as a potential option regarding the neutrino mass ordering in nature. On the basis of the derived equation of neutrino motion, a possible numerical value of the Dirac CP violation phase and Jarlskog invariant is found.
hep-ph0 citations
13*
Large power spectrum and primordial black holes in the effective theory of inflation
Guillermo Ballesteros🇪🇸 · Sebastián Céspedes🇪🇸 · Luca Santoni🇺🇸
We study the generation of a large power spectrum, necessary for primordial black hole formation, within the effective theory of single-field inflation. The mechanisms we consider include a transition into a ghost-inflation-like phase and scenarios where an exponentially growing mode is temporarily turned on. In the cases we discuss, the enhancement in the power spectrum results from either a swift change in some effective coupling or a modification of the dispersion relation for the perturbations, while the background evolution remains unchanged and approximately de Sitter throughout inflation. The robustness of the results is guaranteed thanks to a weakly broken galileon symmetry, which protects the effective couplings against large quantum corrections. We discuss how the enhancement of the power spectrum is related to the energy scale of the operators with weakly broken galileon invariance, and study the limits imposed by strong coupling and the validity of the perturbative expansion.
↳ hep-thastro-ph.COgr-qchep-phJHEP(2022)·43 citations
14*
Probing triaxial deformation of atomic nuclei in high-energy heavy ion collisions
Jiangyong Jia🇺🇸
Most atomic nuclei are deformed with a quadrupole shape described by its overall strength $β_{2}$ and triaxiality $γ$ . The deformation can be accessed in high-energy heavy-ion collisions by measuring the collective flow response of the produced quark-gluon plasma to the eccentricity $ε_{2}$ and the density gradient $d_{⊥}$ in the initial state. Using analytical estimate and a Glauber model, I show that the variances, $⟨ ε_{2}^{2} ⟩$ or $⟨(δ d_{⊥} / d_{⊥})^{2} ⟩$ , and skewnesses, $⟨ ε_{2}^{2} δ d_{⊥} / d_{⊥} ⟩$ or $⟨(δ d_{⊥} / d_{⊥})^{3} ⟩$ , have a simple analytical form of $a^{'} + b^{'} β_{2}^{2}$ and $a^{'} + (b^{'} + c^{'} cos (3 γ)) β_{2}^{3}$ , respectively. From these, I constructed several normalized skewnesses to isolate the $γ$ dependence from that of $β_{2}$ , and show that the correlations between any normalized skewness and any variance can constrain simultaneously the $β_{2}$ and $γ$ . Assuming a linear relation with elliptic flow $v_{2}$ and mean-transverse momentum $[p_{T}]$ of final state particles, similar conclusions are also expected for the variances and skewnesses of $v_{2}$ and $[p_{T}]$ . Our findings motivate a dedicated system scan of high-energy heavy ion collisions to measure triaxiality of atomic nuclei. This is better done by collisions of prolate, $cos (3 γ) = 1$ , and oblate nuclei, $cos (3 γ) = - 1$ , with well known $β_{2}$ values to calibrate the coefficients $b^{'}$ and $c^{'}$ , followed by collisions of species of interest especially those with known $β_{2}$ but unknown $γ$ . The results demonstrate the unique opportunities offered by high-energy collisions as a tool to perform interdisciplinary nuclear physics studies.
↳ nucl-thhep-phnucl-exPRC(2022)·108 citations
15*
Tracking charged particles in the zero curvature limit
J. Alcaraz Maestre (CIEMAT-Madrid)🇪🇸
In this report we discuss appropriate strategies for the tracking of charged particles in the limit of zero curvature. The suggested approach avoids special treatments and precision issues that frequently arise in that limit. We provide explicit expressions for transport, refitting and vertexing in regions where magnetic field inhomogeneities or detector interaction effects can be approximately ignored.
↳ physics.ins-dethep-exhep-ph1 citation
16*
Semiempirical formula for electroweak response functions in the two-nucleon emission channel in neutrino-nucleus scattering
V.L. Martinez-Consentino🇪🇸 · J.E. Amaro🇪🇸 · I. Ruiz Simo🇪🇸
A semi-empirical formula for the electroweak response functions in the two-nucleon emission channel is proposed. The method consists in expanding each one of the vector-vector, axial-axial and vector-axial responses as sums of six sub-responses. These corresponds to separating the meson-exchange currents as the sum of three currents of similar structure, and expanding the hadronic tensor, as the sum of the separate contributions from each current plus the interferences between them. For each sub-response we factorize the coupling constants, the electroweak form factors, the phase space and the delta propagator, for the delta forward current. The remaining spin-isospin contributions are encoded in coefficients for each value of the momentum transfer, $q$ . The coefficients are fitted to the exact results in the relativistic mean field model of nuclear matter, for each value of $q$ . The dependence on the energy transfer, $ω$ is well described by the semi-empirical formula. The $q$ -dependency of the coefficients of the sub-responses can be parameterized or can be interpolated from the provided tables. The description of the five theoretical responses is quite good. The parameters of the formula, the Fermi momentum, number of particles relativistic effective mass, vector energy the electroweak form factors and the coupling constants, can be modified easily. This semi-empirical formula can be applied to the cross-section of neutrinos, antineutrinos and electrons.
↳ nucl-thhep-phPRD(2021)·21 citations
17*
The dark side of the torsion: Dark Energy from propagating torsion
David Benisty🇬🇧 · Eduardo I. Guendelman🇮🇱 · Armin van de Venn🇩🇪 · David Vasak🇩🇪 · Jürgen Struckmeier🇩🇪 · Horst Stoecker🇩🇪
An extension to the Einstein-Cartan (EC) action is discussed in terms of cosmological solutions. The torsion incorporated in the EC Lagrangian is assumed to be totally anti-symmetric, represented by a time-like axial vector $S^{μ}$ . The dynamics of torsion is invoked by a novel kinetic term. Here we show that this kinetic term gives rise to dark energy, while the quadratic torsion term, emanating from the EC part, represents a stiff fluid that leads to a bouncing cosmology solution. A constraint on the bouncing solution is calculated using cosmological data from different epochs.
↳ astro-ph.COgr-qchep-phEPJC(2022)·40 citations
18*
Monopoles Entangle Fermions
Csaba Csáki🇺🇸 · Yuri Shirman🇺🇸 · Ofri Telem🇺🇸 · John Terning🇺🇸
We resolve the decades old mystery of what happens when a positron scatters off a minimal GUT monopole in an s-wave, first discussed by Callan in 1983. Using the language of on-shell amplitudes and pairwise helicity we show that the final state contains two up quarks and a down quark entangled with angular momentum stored in the gauge fields, which is the only particle final state that satisfies angular momentum and gauge charge conservation. The cross section for this process is as large as in the original Rubakov-Callan effect, only suppressed by the QCD scale. The final state we find cannot be seen in Callan's truncated 2D theory, since our entanglement requires more than 2 dimensions.
↳ hep-thhep-phPRL(2022)·31 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.