HEP Phenomenology·hep-ph

Wed·Feb 7, 2018Wednesday·February 7, 2018

19 papers—15 primary·4 cross-listed·reconstructed*

01*
$hh + jet$ production at 100 TeV
Shankha Banerjee🇬🇧 · Christoph Englert🇬🇧 · Michelangelo L. Mangano🇨🇭 · Michele Selvaggi🇨🇭 · Michael Spannowsky🇬🇧
Higgs pair production is a crucial phenomenological process in deciphering the nature of the TeV scale and the mechanism underlying electroweak symmetry breaking. At the Large Hadron Collider, this process is statistically limited. Pushing the energy frontier beyond the LHC's reach will create new opportunities to exploit the rich phenomenology at higher centre-of-mass energies and luminosities. In this work, we perform a comparative analysis of the $hh + jet$ channel at a future 100 TeV hadron collider. We focus on the $hh \to b b ˉ b b ˉ$ and $hh \to b b ˉ τ^{+} τ^{-}$ channels and employ a range of analysis techniques to estimate the sensitivity potential that can be gained by including this jet-associated Higgs pair production to the list of sensitive collider processes in such an environment. In particular, we observe that $hh \to b b ˉ τ^{+} τ^{-}$ in the boosted regime exhibits a large sensitivity to the Higgs boson self-coupling and the Higgs self-coupling could be constrained at the 8\% level in this channel alone.
hep-phhep-exEPJC(2018)·35 citations
02*
A Sterile Neutrino Origin for the Upward Directed Cosmic Ray Showers Detected by ANITA
John F. Cherry🇺🇸 · Ian Shoemaker🇺🇸
The ANITA balloon experiment has recently observed several ~EeV cascade events at an angle below the horizon that renders any Standard Model (SM) interpretation unlikely as the Earth is significantly opaque to all SM particles at such energies. In this paper, we study a sterile neutrino interpretation of these events, calculating the angular acceptance of cascades and the relative sensitivities of several experiments to a cascade initiated by an EeV sterile neutrino. We find that ANITA is uniquely sensitive to this type of upward directed cascade signal over a wide portion of the sky and from the direction of the two observed events has a transient acceptance roughly equivalent to that of the IceCube experiment.
hep-phastro-ph.HEPRD(2019)·62 citations
03*
Status of the semileptonic $B$ decays and muon g-2 in general 2HDMs with right-handed neutrinos
Syuhei Iguro🇯🇵 · Yuji Omura🇯🇵
In this paper, we study the extended Standard Model (SM) with an extra Higgs doublet and right-handed neutrinos. If the symmetry to distinguish the two Higgs doublets is not assigned, flavor changing neutral currents (FCNCs) involving the scalars are predicted even at the tree level. We investigate the constraints on the FCNCs at the one-loop level, and especially study the semileptonic $B$ meson decays, e.g. $B \to D^{(*)} τ ν$ and $B \to K^{(*)} l l$ processes, where the SM predictions are more than $2 σ$ away from the experimental results. We also consider the flavor-violating couplings involving right-handed neutrinos and discuss if the parameters to explain the excesses of the semileptonic $B$ decays can resolve the discrepancy in the the anomalous muon magnetic moment. Based on the analysis, we propose the smoking-gun signals of our model at the LHC.
hep-phhep-exJHEP(2018)·89 citations
04*
Corrections to $R_{D}$ and $R_{D^{*}}$ in the BLMSSM
Zhong-Jun Yang🇨🇳 · Shu-Min Zhao🇨🇳 · Xing-Xing Dong🇨🇳 · Xi-Jie Zhan🇨🇳 · Hai-Bin Zhang🇨🇳 · Tai-Fu Feng🇨🇳
The deviation of the measurement of $R_{D}$ ( $R_{D^{*}}$ ) from the Standard Model (SM) expectation is $2.3 σ$ ( $3.1 σ$ ). $R_{D}$ ( $R_{D^{*}}$ ) is the ratio of the branching fraction of $B \to D τ ν_{τ}$ ( $B \to D^{*} τ ν_{τ}$ ) to that of $B \to D l ν_{l}$ ( $B \to D^{*} l ν_{l}$ ), where $l = e$ or $μ$ . This anomaly may imply the existence of new physics (NP). In this paper, we restudy this problem in the supersymmetric extension of the Standard Model with local gauged baryon and lepton numbers (BLMSSM), and give one-loop corrections to $R_{D}$ ( $R_{D^{*}}$ ).
hep-phCPC(2018)·5 citations
05*
Neutron Lifetime and Axial Coupling Connection
Andrzej Czarnecki🇨🇦 · William J. Marciano🇺🇸 · Alberto Sirlin🇺🇸
Experimental studies of neutron decay, $n \to p e ν ˉ$ , exhibit two anomalies. The first is a 8.6(2.1)s, roughly $4 σ$ difference between the average beam measured neutron lifetime, $τ_{n}^{beam} = 888.0 (2.0)$ s, and the more precise average trapped ultra cold neutron determination, $τ_{n}^{trap} = 879.4 (6)$ s. The second is a $5 σ$ difference between the pre2002 average axial coupling, $g_{A}$ , as measured in neutron decay asymmetries $g_{A}^{pre2002} = 1.2637 (21)$ , and the more recent, post2002, average $g_{A}^{post2002} = 1.2755 (11)$ , where, following the UCNA collaboration division, experiments are classified by the date of their most recent result. In this study, we correlate those $τ_{n}$ and $g_{A}$ values using a (slightly) updated relation $τ_{n} (1 + 3 g_{A}^{2}) = 5172.0 (1.1)$ s. Consistency with that relation and better precision suggest $τ_{n}^{favored} = 879.4 (6)$ s and $g_{A}^{favored} = 1.2755 (11)$ as preferred values for those parameters. Comparisons of $g_{A}^{favored}$ with recent lattice QCD and muonic hydrogen capture results are made. A general constraint on exotic neutron decay branching ratios, $< 0.27%$ , is discussed and applied to a recently proposed solution to the neutron lifetime puzzle.
hep-phPRL(2018)·196 citations
06*
The second lightest CP-even Higgs boson signals in the NMSSM at the LHC
M. M. Almarashi🇸🇦
We study the signal rates of the second lightest CP-even Higgs boson, $h_{2}$ , of the NMSSM produced in gluon fusion, in association with bottom quarks and in association with top quarks, which is not the SM-like Higgs boson, at the LHC. We evaluate the production rates of the $h_{2}$ in the SM fermionic and bosonic final states in addition to $a_{1} a_{1}$ , $h_{1} h_{1}$ and $Z a_{1}$ final states. It is observed that the size of the signal rates in some regions of the NMSSM parameter space is quite large and that could help extracting the $h_{2}$ signals at the LHC through a variety of decay channels.
hep-phInt.J.Mod.Phys.A(2018)·2 citations
07*
Chiral density wave versus pion condensation at finite density
Jens O. Andersen🇳🇴 · Patrick Kneschke🇳🇴
The quark-meson model is often used as an effective low-energy model for QCD to study the chiral transition at finite temperature $T$ , baryon chemical potential $μ_{B}$ , and isospin chemical potential $μ_{I}$ . The parameters of the model are determined by matching the meson and quark masses, as well as the pion decay constant to their physical values using the on-shell and modified minimal subtraction schemes. In this paper, we study the possibility of different phases at zero temperature. In particular, we investigate the competition between an inhomogeneous chiral condensate and a pion condensate. For the inhomogeneity, we use a chiral-density wave ansatz. For a sigma mass of $600$ MeV, we find that an inhomogeneous chiral condensate exist only for pion masses below approximately 37 MeV. We also show that due to our parameter fixing, the onset of pion condensation takes place exactly at $μ_{I} = \frac{1}{2} m_{π}$ in accordance with exact results.
hep-phPRD(2018)·35 citations
08*
Double Collins effect in $e^{+} e^{-} \to Λ Λ ˉ X$ process in a diquark spectator model
Xiaoyu Wang🇨🇳 · Yongliang Yang🇨🇳 · Zhun Lu🇨🇳
We study the Collins function $H_{1}^{⊥}$ of the $Λ$ hyperon, which describes the fragmentation of a transversely polarized quark into an unpolarized $Λ$ hyperon. We calculate $H_{1}^{⊥}$ for light quarks of the $Λ$ hyperon, in the diquark spectator model with a Gaussian form factor for the hyperon-quark-diquark vertex. The model calculation includes contributions from both the scalar diquark and vector diquark spectators. Using the model result, we estimate the weighted $cos 2 ϕ_{0}$ asymmetry in the process $e^{+} e^{-} \to Λ Λ ˉ X$ contributed by the coupling of two Collins functions. The QCD evolution effects for the first $k_{T}$ -moment of the Collins function and the unpolarized fragmentation function $D_{1} (z)$ are also included. The results show that asymmetry is sizable and measurable at the kinematical configurations of Belle and BaBar experiments. We also find that the evolution effects play an important role in the phenomenological analysis.
hep-phhep-exPRD(2018)·9 citations
09*
Hadron resonance gas EoS and the fluidity of matter produced in HIC
Guruprasad Kadam🇮🇳 · Swapnali Pawar🇮🇳
We study the equation of state (EoS) of the hot and dense hadron gas by incorporating the excluded volume corrections into the ideal hadron resonance gas model (HRG). The total hadron mass spectrum of the model is the sum of discrete mass spectrum consisting all the experimentally known hadrons and the exponentially rising continuous Hagedorn states. We confront the EoS of the model with lattice quantum chromodynamics (LQCD) results at finite baryon chemical potential. We find that this modified HRG model reproduce the LQCD results up to T = 160 MeV at zero as well as finite baryon chemical potential. We further estimate the shear viscosity coefficient within ambit of this model in the context of heavy-ion collision experiments.
hep-phnucl-thAdv.High Energy Phys.(2019)·11 citations
10*
Heavy meson dissociation in a plasma with magnetic fields
Nelson R. F. Braga🇧🇷 · Luiz F. Ferreira🇧🇷
The fraction of heavy vector mesons detected after a heavy ion collision provides information about the possible formation of a plasma state. An interesting framework for estimating the degree of dissociation of heavy mesons in a plasma is the holographic approach. It has been recently shown that a consistent picture for the thermal behavior of charmonium and bottomonium states in a thermal medium emerges from holographic bottom up models. A crucial ingredient in this new approach is the appropriate description of decay constants, since they are related to the heights of the quasiparticle peaks of the finite temperature spectral function. Here we extend this new holographic model in order to study the effect of magnetic fields on the thermal spectrum of heavy mesons. The motivation is that very large magnetic fields are present in non central heavy ion collisions and this could imply a change in the dissociation scenario. The thermal spectra of $c c ˉ$ and $b b ˉ$ S wave states is obtained for different temperatures and different values of the magnetic $e B$ field.
hep-phPLB(2018)·64 citations
11*
Exact Solution of the N-dimensional Radial Schrödinger Equation via Laplace Transformation Method with the Generalized Cornell Potential
M. Abu-Shady🇪🇬 · T. A. Abdel-Karim🇪🇬 · E. M. Khokha🇪🇬
The exact solution of N- dimensional radial Schrödinger equation with the generalized Cornell potential has been obtained using the Laplace transformation (LT) method. The energy eigenvalues and the corresponding wave functions for any state have been determined. The eigenvalues for some special cases of the generalized Cornell potential are obtained. The present results are applied to calculate the mass spectra of heavy quarkonium systems such as charmonium and bottomonium and the bc meson. A comparison is discussed with the experimental data and recent works. The present results are improved in comparison with other recent studies and are in a good agreement with the experimental data. The effect of the dimensional number (N) on the meson masses has been studied. We note that the meson masses increase in higher dimensions.
hep-ph9 citations
12*
Diphoton production at the LHC: a QCD study up to NNLO
Stefano Catani🇮🇹 · Leandro Cieri🇮🇹 · Daniel de Florian🇦🇷 · Giancarlo Ferrera🇮🇹 · Massimiliano Grazzini🇨🇭
We consider the production of prompt-photon pairs at the LHC and we report on a study of QCD radiative corrections up to the next-to-next-to-leading order (NNLO). We present a detailed comparison of next-to-leading order (NLO) results obtained within the standard and smooth cone isolation criteria, by studying the dependence on the isolation parameters. We highlight the role of different partonic subprocesses within the two isolation criteria, and we show that they produce large radiative corrections for both criteria. Smooth cone isolation is a consistent procedure to compute QCD radiative corrections at NLO and beyond. If photon isolation is sufficiently tight, we show that the NLO results for the two isolation procedures are consistent with each other within their perturbative uncertainties. We then extend our study to NNLO by using smooth cone isolation. We discuss the impact of the NNLO corrections and the corresponding perturbative uncertainties for both fiducial cross sections and distributions, and we comment on the comparison with some LHC data. Throughout our study we remark the main features that are produced by the kinematical selection cuts that are applied to the photons. In particular, we examine soft-gluon singularities that appear in the perturbative computations of the invariant mass distribution of the photon pair, the transverse-momentum spectra of the photons, and the fiducial cross section with asymmetric and symmetric photon transverse-momentum cuts, and we present their behaviour in analytic form.
hep-phJHEP(2018)·81 citations
13*
Exploring the Potential of Short-Baseline Physics at Fermilab
O. G. Miranda🇲🇽 · Pedro Pasquini🇧🇷 · M. Tórtola🇪🇸 · J. W. F. Valle🇪🇸
We study the capabilities of the short baseline neutrino program at Fermilab to probe the unitarity of the lepton mixing matrix. We find the sensitivity to be slightly better than the current one. Motivated by the future DUNE experiment, we have also analyzed the potential of an extra liquid Argon near detector in the LBNF beamline. Adding such a near detector to the DUNE setup will substantially improve the current sensitivity on non-unitarity. This would help to remove CP degeneracies due to the new complex phase present in the neutrino mixing matrix. We also study the sensitivity of our proposed setup to light sterile neutrinos for various configurations.
hep-phhep-exPRD(2018)·33 citations
14*
Collider constraints on light pseudoscalars
Ulrich Haisch🇬🇧 · Jernej F. Kamenik🇸🇮 · Augustinas Malinauskas🇬🇧 · Michael Spira🇨🇭
We investigate the bounds on light pseudoscalars that arise from a variety of collider searches. Special attention is thereby devoted to the mass regions $[3, 5] GeV$ and $[9, 11] GeV$ , in which a meaningful theoretical description has to include estimates of non-perturbative effects such as the mixing of the pseudoscalar with QCD bound states. A compendium of formulas that allows to deal with the relevant corrections is provided. It should prove useful for the interpretation of future LHC searches for light CP-odd spin-0 states.
hep-phhep-exJHEP(2018)·71 citations
15*
Heavy flavour energy loss from AdS/CFT: A novel diffusion coefficient
Robert Hambrock🇿🇦 · William Alexander Horowitz🇿🇦
Two AdS/CFT based energy loss models are used to compute the suppression and azimuthal correlations of heavy quarks in heavy ion collisions. The model with a velocity independent diffusion coefficient is in good agreement with B and D meson data up to high $p_{T}$ . The partonic azimuthal correlations we calculate exhibit an order of magnitude difference in low momentum correlations to pQCD calculations [arXiv:1305.3823]. We thus propose heavy flavour momentum correlations as a distinguishing observable of weakly- and strongly-coupled energy loss mechanisms.
hep-phEPJ Web Conf.(2018)·6 citations
16*
KLT-type relations for QCD and bicolor amplitudes from color-factor symmetry
Robert W. Brown🇺🇸 · Stephen G. Naculich🇺🇸
Color-factor symmetry is used to derive a KLT-type relation for tree-level QCD amplitudes containing gluons and an arbitrary number of massive or massless quark-antiquark pairs, generalizing the expression for Yang-Mills amplitudes originally postulated by Bern, De Freitas, and Wong. An explicit expression is given for all amplitudes with two or fewer quark-antiquark pairs in terms of the (modified) momentum kernel. We also introduce the bicolor scalar theory, the "zeroth copy" of QCD, containing massless biadjoint scalars and massive bifundamental scalars, generalizing the biadjoint scalar theory of Cachazo, He, and Yuan. We derive KLT-type relations for tree-level amplitudes of biadjoint and bicolor theories using the color-factor symmetry possessed by these theories.
↳ hep-thhep-phJHEP(2018)·30 citations
17*
Impact of medium modification of the nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter
Parada T. P. Hutauruk🇰🇷 · Yongseok Oh🇰🇷 · K. Tsushima🇧🇷
Impact of the in-medium modified nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter is studied by considering both the weak and electromagnetic interactions of neutrinos with the constituents of the matter. A relativistic mean field model and the quark-meson coupling model are respectively adopted for the in-medium effective nucleon mass and nucleon form factors. We find that the cross sections of neutrino scattering in cold nuclear medium decreases when the in-medium modification of the nucleon weak and electromagnetic form factors are taken into account. This reduction results in the enhancement of the neutrino mean free path, in particular at the baryon density of around a few times of the normal nuclear matter density. The enhancement of the neutrino mean free path is estimated to be about 10--40\% compared with the values obtained without the medium modification of the nucleon form factors, and the enhancement is expected to accelerate the cooling of neutron stars.
↳ nucl-thastro-ph.HEhep-exhep-ph+1PRD(2018)·15 citations
18*
Causal Classical Physics in Time Symmetric Quantum Mechanics
Fritz W. Bopp🇩🇪
The letter submitted is an executive summary of our previous paper. To solve the Einstein Podolsky Rosen 'paradox' the two boundary quantum mechanics is taken as self consistent interpretation of quantum dynamics. The difficulty with this interpretation is to reconcile it with classical physics. To avoid macroscopic backward causation two 'corresponding transition rules' are formulated which specify needed properties of macroscopic observations and manipulations. The apparent classical causal decision tree requires to understand the classically unchosen options. They are taken to occur with an 'incomplete knowledge' of the boundary states typically in macroscopic considerations. The precise boundary conditions with given phases then select the actual measured path and this selection is mistaken to happen at the time of measurement. The apparent time direction of the decision tree originates in an assumed relative proximity to the initial state. Only the far away final state allows for classically distinct options to be selected from. Cosmologically the picture could correspond to a big bang initial and a hugely extended final state scenario. It is speculated that it might also hold for a big bang/big crunch world. If this would be the case the Born probability postulate could find a natural explanation if we coexist in the expanding and the correlated CPT conjugate contracting world.
↳ quant-phhep-phphysics.hist-phMDPI Proc.(2018)·4 citations
19*
Pushing the precision frontier at the LHC with V+jets
Ulla Blumenschein🇬🇧 · Shane Breeze🇬🇧 · Chiara Debenedetti🇺🇸 · Engin Eren🇩🇪 · Simona Gargiulo🇩🇪 · Nigel Glover🇬🇧 · Jonas M. Lindert🇬🇧 · Daniel Maitre🇬🇧 · Sarah A. Malik🇬🇧 · Bjoern Penning🇬🇧 · Svenja K. Pflitsch🇩🇪 · Darren Price🇬🇧 and 7 other authors
This documents the proceedings from a workshop titled `Illuminating Standard candles at the LHC: V+jets' held at Imperial College London on 25th-26th April 2017. It summarises the numerous contributions to the workshop, from the experimental overview of V+jets measurements at CMS and ATLAS and their role in searching for physics beyond the Standard Model to the status of higher order perturbative calculations to these processes and their inclusion in state of the art Monte Carlo simulations. An executive summary of the ensuing discussions including a list of outcomes and wishlist for future consideration is also presented.
↳ hep-exhep-ph15 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.