Master Thesis Open Access
Heidelbach, Alexander
<?xml version='1.0' encoding='UTF-8'?> <record xmlns="http://www.loc.gov/MARC21/slim"> <leader>00000nam##2200000uu#4500</leader> <datafield tag="980" ind1=" " ind2=" "> <subfield code="a">user-belle2</subfield> </datafield> <datafield tag="980" ind1=" " ind2=" "> <subfield code="a">user-etp</subfield> </datafield> <datafield tag="100" ind1=" " ind2=" "> <subfield code="a">Heidelbach, Alexander</subfield> <subfield code="u">KIT/ETP</subfield> </datafield> <datafield tag="542" ind1=" " ind2=" "> <subfield code="l">open</subfield> </datafield> <datafield tag="260" ind1=" " ind2=" "> <subfield code="c">2022-04-28</subfield> </datafield> <datafield tag="909" ind1="C" ind2="O"> <subfield code="o">oai:publish.etp.kit.edu:22123</subfield> <subfield code="p">user-belle2</subfield> <subfield code="p">user-etp</subfield> </datafield> <datafield tag="245" ind1=" " ind2=" "> <subfield code="a">Sensitivity Study in the Search for $B^{\pm}\to K^{\pm}a$ (displaced $a\to\gamma\gamma$) Decays at Belle II</subfield> </datafield> <datafield tag="856" ind1="4" ind2=" "> <subfield code="s">14481492</subfield> <subfield code="u">https://publish.etp.kit.edu/record/22123/files/Thesis_ETP_AlexanderHeidelbach.pdf</subfield> <subfield code="z">md5:2a0a64db8044ee5d6027325d9dfc7b5c</subfield> </datafield> <controlfield tag="001">22123</controlfield> <datafield tag="041" ind1=" " ind2=" "> <subfield code="a">eng</subfield> </datafield> <controlfield tag="005">20220707093850.0</controlfield> <datafield tag="653" ind1=" " ind2=" "> <subfield code="a">Belle II</subfield> </datafield> <datafield tag="653" ind1=" " ind2=" "> <subfield code="a">Analysis</subfield> </datafield> <datafield tag="653" ind1=" " ind2=" "> <subfield code="a">Search for New Physics</subfield> </datafield> <datafield tag="653" ind1=" " ind2=" "> <subfield code="a">ALPs</subfield> </datafield> <datafield tag="700" ind1=" " ind2=" "> <subfield code="a">Ferber, Torben</subfield> <subfield code="u">KIT/ETP</subfield> <subfield code="4">ths</subfield> </datafield> <datafield tag="700" ind1=" " ind2=" "> <subfield code="a">Quast, Günter</subfield> <subfield code="u">KIT/ETP</subfield> <subfield code="4">ths</subfield> </datafield> <datafield tag="520" ind1=" " ind2=" "> <subfield code="a"><p>In a set of simple extensions of the Standard Model, Axion Like Particles (ALPs) arise as pseudo Nambu-Goldstone bosons of theories with a spontaneously broken Peccei-Quinn symmetry that is anomalous under the Standard Model gauge symmetry. Due to constraints in flavour-changing current &nbsp;(FCNC) processes, involving the coupling of ALPs directly to Standard Model fermions and gluons, direct couplings of ALPs to the electroweak gauge bosons are particularly interesting. As a result of a coupling to $W$ bosons, ALPs can emerge in FCNC $b\to s$ transitions. Depending on the ALP mass and the coupling strength to photons a possible experimental signature is $B^{\pm}\to K^{\pm}a, a\to\gamma\gamma$ with long lived ALP decays. This thesis performs a sensitivity study in the search for the $B^{\pm}\to K^{\pm}a, a\to\gamma\gamma$ signature based on Belle II simulation samples corresponding to an integrated luminosity of 100\,fb$^{-1}$. The sensitivity study includes an optimised candidate selection and signal yield scans of the invariant di-photon mass distribution in the range of $0.175\,\text{GeV/c}^2$ to $4.600\,\text{GeV/c}^2$ for eight different ALP lifetimes between $0\,\text{cm}$ and $50\,\text{cm}$. Resulting expected limits are comparable to a similar search for $B^{\pm}\to K^{\pm}a, a\to\gamma\gamma$ on data collected by the BABAR experiment.&nbsp;</p></subfield> </datafield> <datafield tag="980" ind1=" " ind2=" "> <subfield code="a">thesis</subfield> <subfield code="b">master-thesis</subfield> </datafield> </record>