<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-04-17T10:49:24Z</responseDate><request verb="GetRecord" identifier="oai:www.recercat.cat:20.500.14342/3156" metadataPrefix="marc">https://recercat.cat/oai/request</request><GetRecord><record><header><identifier>oai:recercat.cat:20.500.14342/3156</identifier><datestamp>2025-03-11T04:11:59Z</datestamp><setSpec>com_2072_482405</setSpec><setSpec>com_2072_183628</setSpec><setSpec>col_2072_482415</setSpec></header><metadata><record xmlns="http://www.loc.gov/MARC21/slim" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.loc.gov/MARC21/slim http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd">
   <leader>00925njm 22002777a 4500</leader>
   <datafield ind2=" " ind1=" " tag="042">
      <subfield code="a">dc</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">Badalov, Alexey</subfield>
      <subfield code="e">author</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">Calvo Gómez, Míriam</subfield>
      <subfield code="e">author</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">Vilasís Cardona, Xavier</subfield>
      <subfield code="e">author</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">LHCb Collaboration - CERN</subfield>
      <subfield code="e">author</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="260">
      <subfield code="c">2015-04-09</subfield>
   </datafield>
   <datafield ind2=" " ind1=" " tag="520">
      <subfield code="a">A search for the rare decays B0s→π+π−μ+μ−and B0→π+π−μ+μ−is performed in a data set corresponding to an integrated luminosity of 3.0fb−1collected by the LHCb detector in proton–proton collisions at centre-of-mass energies of 7 and 8TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5–1.3GeV/c2and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B0s→π+π−μ+μ−and the first evidence of the decay B0→π+π−μ+μ−are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(B0s→π+π−μ+μ−) =(8.6 ±1.5(stat) ±0.7(syst) ±0.7 (norm)) ×10−8and B(B0→π+π−μ+μ−) =(2.11±0.51(stat)±0.15(syst)±0.16(norm))×10−8, where the third uncertainty is due to the branching fraction of the decay B0→J/ψ(→μ+μ−)K∗(892)0(→K+π−), used as a normalisation.</subfield>
   </datafield>
   <datafield ind1="8" ind2=" " tag="024">
      <subfield code="a">http://hdl.handle.net/20.500.14342/3156</subfield>
   </datafield>
   <datafield ind1="8" ind2=" " tag="024">
      <subfield code="a">https://doi.org/10.1016/j.physletb.2015.02.010</subfield>
   </datafield>
   <datafield tag="653" ind2=" " ind1=" ">
      <subfield code="a">Gran col·lisionador d'hadrons (França i Suïssa)</subfield>
   </datafield>
   <datafield tag="653" ind2=" " ind1=" ">
      <subfield code="a">Partícules (Física nuclear)</subfield>
   </datafield>
   <datafield tag="653" ind2=" " ind1=" ">
      <subfield code="a">Protons</subfield>
   </datafield>
   <datafield tag="653" ind2=" " ind1=" ">
      <subfield code="a">Col·lisions (Física nuclear)</subfield>
   </datafield>
   <datafield ind2="0" ind1="0" tag="245">
      <subfield code="a">Study of the rare B0s and B0 decays into the π+ π− μ+ μ− final state</subfield>
   </datafield>
</record></metadata></record></GetRecord></OAI-PMH>